TY - CONF
TI - Interface characterization of candidate dual-purpose barrier coatings for SiC/SiC accident tolerant fuel cladding
AU - Kabel, J.
AU - Koyanagi, T.
AU - Katoh, Y.
AU - Schoell, R.
AU - Kaoumi, D.
AU - Ang, C.
AU - Hosemann, P.
C2 - 2019///
C3 - 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, EnvDeg 2019
DA - 2019///
SP - 1043-1051
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85080034549&partnerID=MN8TOARS
ER -
TY - RPRT
TI - Summary of Grizzly Development for Advanced Reactor Structural Materials
AU - Spencer, Benjamin
AU - Pitts, Stephanie
AU - Liu, Ling
AU - Vyas, Manu
AU - Jiang, Wen
AU - Casagranda, Albert
AU - McDowell, Dylan
A3 - Office of Scientific and Technical Information (OSTI)
AB - This summary report contains an overview of work performed during Fiscal Year 2019 under the Nuclear Engineering Advanced Modeling and Simulation (NEAMS) Fuels Product Line work package entitled "MS-19IN020106 - GRIZZLY - INL". Grizzly is a code based on the MOOSE framework that has been under development for several years funded by the US Department of Energy’s Light Water Reactor Sustainability (LWRS) program. Prior to 2019, Grizzly development was focused on development of capabilities needed to simulate the effects of aging mechanisms in light water reactor (LWR) components. The goal of this LWR-focused work has been to develop tools that can be used to assess the ability of existing LWRs to perform safety in long term operation (LTO) scenarios. This LWR-focused work has primarily focused on the effects of reactor pressure vessel (RPV) embrittlement and aging of reinforced concrete structures. Grizzly development to support LWR degradation needs is still ongoing, but starting in 2019, Grizzly’s capabilities are being expanded to also meet growing needs for a tool to address structural component integrity and degradation in advanced reactors. A simulation capability for advanced reactor components has many of the same basic requirements that one for LWRs does, such as the ability to solve coupled systems of partial differential equations that arise from the fact that many of the problems of interest involve multiple coupled physics. The materials issues also inherently involve multiple length scales, with the response at the engineering scale being strongly affected by mechanisms occurring at atomistic and mesoscopic scales.
DA - 2019/9/30/
PY - 2019/9/30/
DO - 10.2172/1572400
PB - Office of Scientific and Technical Information (OSTI)
UR - https://doi.org/10.2172/1572400
ER -
TY - RPRT
TI - Quarterly Management Document – FY19, 4th Quarter, Physics-based Creep Simulations of Thick Section Welds in High Temperature and Pressure Applications
AU - Lillo, Thomas M
AU - Jiang, Wen
AB - During the 4th quarter of FY19, diffusional creep effects, based on the local stress tensor, was incorporated into the modeling and simulation efforts on thick section welds of Alloy 740H. The model is now complete and addresses both dislocation-based creep as well as diffusional creep mechanisms. Preliminary result indicate the model is now capable of predicting a transition from secondary creep to tertiary creep. Calibration of the model using experimental creep data remains to be performed and will be done in the first quarter of FY20.
DA - 2019/11/4/
PY - 2019/11/4/
DO - 10.2172/1596099
UR - https://doi.org/10.2172/1596099
ER -
TY - RPRT
TI - Quarterly Management Document – FY19, 3rd Quarter, Physics-based Creep Simulations of Thick Section Welds in High Temperature and Pressure Applications
AU - Lillo, Thomas M
AU - Jiang, Wen
AB - During the 3rd quarter of FY19, a strategy was developed to incorporate creep damage arising from diffusional processes into a computational model describing creep behavior of thick section welds in Alloy 740H. This approach will be followed in the 4th quarter modify the existing creep model to include diffusional damage processes in its predictions of creep behavior and especially the transition to tertiary creep behavior which will allow the prediction of creep rupture time.
DA - 2019/8/6/
PY - 2019/8/6/
DO - 10.2172/1547327
UR - https://doi.org/10.2172/1547327
ER -
TY - RPRT
TI - Summary of Bison milestones and activities - NEAMS FY2019 Report
AU - Novascone, Stephen
AU - Casagranda, Albert
AU - Aagesen, Larry, Jr.
AU - Beeler, B.
AU - Jiang, Wen
AU - Jokisaari, Andrea
AU - McDowell, Dylan
AU - Lindsay, Alexander
AU - Tompkins, James
AU - Pastore, Giovanni
AU - Zabriskie, Adam
AU - Schwen, Daniel
AU - Williamson, Richard
AU - Spencer, Benjamin
AU - Slaughter, Andrew
AU - Miao, Yinbin
AU - Oaks, Aaron
AU - Yacout, Abdellatif
AU - Matthews, C.
AU - Stafford, Shane
AB - This summary report contains an overview of work performed under the work package entitled “FY2019 NEAMS Engineering Scale Fuel Performance”, which is focused on the development and support of the fuel performance code Bison [1]. The second chapter lists FY19 milestones titles, completion schedule, and milestone level. Subsequent chapters summarize and demonstrate completion of milestones and activities. The last chapter outlines FY20 proposed future work.
DA - 2019/9/1/
PY - 2019/9/1/
DO - 10.2172/1768049
UR - https://doi.org/10.2172/1768049
ER -
TY - JOUR
TI - Steam generator tube rupture in lead-cooled fast reactors: Estimation of impact on neighboring tubes
AU - Iskhakov, A.S.
AU - Melikhov, V.I.
AU - Melikhov, O.I.
AU - Yakush, S.E.
T2 - Nuclear Engineering and Design
AB - Lead-cooled fast reactors have several advantages in comparison to thermal neutron reactors and sodium-cooled fast reactors. Despite the considerable interest of international nuclear power community to this technology, safety issues associated with possible chain rupture of steam generator tubes initiated by rupture of a single tube in the tube bundle have not been completely resolved so far. Such initiating events can cause large dynamic loads on the neighboring tubes, and methods for evaluation of their consequences are to be developed. In this work, approaches are proposed for the estimation of forces acting on neighboring tubes at the initial stage of an accident initiated by tube rupture in a lead-heated steam generator. The forces considered include the shock impact caused by pressure wave propagating in liquid lead, and subsequent hydrodynamic impact caused by high-speed flow of heavy lead around the neighboring tubes. The shock impact is calculated from a model for water droplet evaporation and expansion in liquid lead based on the assumptions that two-phase water mixture is in thermodynamic and mechanical equilibrium, while liquid lead is an inviscid compressible fluid. The hydrodynamic impact is estimated using a simplified model with incompressible liquid lead and volume-averaged two-phase water-vapor mixture properties. Both models are implemented in 1D spherical coordinates. Estimates for the shock and hydrodynamic impact of tube rupture on the neighboring tubes are obtained for the conditions of BREST-OD-300 steam generator.
DA - 2019/1//
PY - 2019/1//
DO - 10.1016/j.nucengdes.2018.11.001
VL - 341
SP - 198-208
UR - http://dx.doi.org/10.1016/j.nucengdes.2018.11.001
ER -
TY - JOUR
TI - Hugoniot analysis of experimental data on steam explosion in stratified melt-coolant configuration
AU - Iskhakov, A.S.
AU - Melikhov, V.I.
AU - Melikhov, O.I.
AU - Yakush, S.E.
AU - Chung, L.T.
T2 - Nuclear Engineering and Design
AB - Recent experimental results on stratified steam explosion are analyzed by the model of “non-ideal” thermal detonation based upon Hugoniot relations, with factors taking into account incomplete melt fragmentation and participation of liquid coolant. The pressure behind the shock wave and conversion ratio are obtained as functions of the mass fraction of melt undergoing fragmentation and mass fraction of coolant in the explosion zone. Calculations are performed for one of the recent experiments on stratified steam explosion carried out with simulant oxidic materials. It is confirmed that the idealized scheme for thermal detonation overestimates significantly the conversion ratio, while predicting very low pressure levels. Taking into account incomplete melt fragmentation and limited participation of coolant improved the agreement between the predictions and experiments. Ranges for the melt fragmentation fraction and mass fraction of participating coolant where the model predictions agree with experimental values are obtained.
DA - 2019/6//
PY - 2019/6//
DO - 10.1016/j.nucengdes.2019.04.004
VL - 347
SP - 151-157
UR - http://dx.doi.org/10.1016/j.nucengdes.2019.04.004
ER -
TY - JOUR
TI - Hugoniot analysis of energetic molten lead-water interaction
AU - Iskhakov, A.S.
AU - Melikhov, V.I.
AU - Melikhov, O.I.
T2 - Annals of Nuclear Energy
AB - Steam generator tube rupture and/or leakage (SGTR/L) is one of the least studied and dangerous safety issues in pool-type lead-cooled fast reactors (LFRs). During this accident, high-pressure water from the secondary circuit is injected into the primary circuit with relatively low-pressure molten lead. One of the possible consequences of SGTR/L is multiphase flow formation consisting water droplets inside vapor bubbles in lead, which could engender a potential explosive coolant-coolant interaction (CCI). The present paper is devoted to the analysis of energetic molten lead-water interaction during SGTR/L in LFRs using Hugoniot adiabats. A review of literature addressing multiphase thermal detonations using Hugoniot adiabats is carried out. Calculations for CCIs are performed which are compared with earlier works and experimental data. Hugoniot analysis is applied to the case of SGTR/L in Russian BREST reactor and detonation velocities and pressures in the Chapman-Jouguet plane are estimated. The mechanical expansion work of the explosion products and the conversion ratios are calculated for typical values of initial void fractions in two-phase water-steam mixture; lead volume fractions and temperatures. Dependencies of the expansion work potential on the void fraction, initial melt volume fraction, and melt temperature are addressed. It is shown that for typical low void fractions for the case of SGTR/L in LFRs the expansion work has a limited value.
DA - 2019/7//
PY - 2019/7//
DO - 10.1016/j.anucene.2019.02.018
VL - 129
SP - 437-449
UR - http://dx.doi.org/10.1016/j.anucene.2019.02.018
ER -
TY - RPRT
TI - Attenuation of Gamma Rays in ArmaKap Ceramic Cement Formulations
AU - Moneghan, Daniel
AU - Eapen, Jacob
AU - Bourham, Mohamed
DA - 2019/2//
PY - 2019/2//
M3 - Armakap Technologies Technical Report
ER -
TY - MGZN
TI - Nuclear forensics via the electronic properties of particulate and samples
AU - Hayes, R.B.
AU - O'Mara, R.P.
AU - Abdelrahman, F.
T2 - ESARDA Bulletin
DA - 2019/12//
PY - 2019/12//
VL - 59
SP - 21–28
ER -
TY - JOUR
TI - Simulator design for low pressure plasma discharges in planar geometry
AU - Radwan, S
AU - Saleh, H
AU - Bourham, M
T2 - IOP Conference Series: Materials Science and Engineering
AB - Abstract A design of a simulator code to determine the plasma characteristics in planar geometry discharges is presented. The experimentally obtained parameters are compared to the code predictions. The experimental plasma discharge characteristics were carried out using 99.99% nitrogen as the working gas at typical pressure values in the range 0.1–0.6 Torr. The simulator code was used to obtain the discharge current-voltage, showing compatibility with experimental values. The minimum breakdown voltage at the minimum gas pressure was also obtained. The relation between the discharge current at different anode-cathode distances was also determined.
DA - 2019/9/1/
PY - 2019/9/1/
DO - 10.1088/1757-899X/610/1/012043
VL - 610
IS - 1
SP - 012043
J2 - IOP Conf. Ser.: Mater. Sci. Eng.
OP -
SN - 1757-8981 1757-899X
UR - http://dx.doi.org/10.1088/1757-899X/610/1/012043
DB - Crossref
ER -
TY - CONF
TI - Small Scale Tensile Testing of Grain Boundary Strength of X-750 Alloy
AU - He, L.
AU - Murray, Daniel
AU - Liu, Xiang
AU - Jiang, Wen
AU - Bachhav, Mukesh
AU - Bai, Xianming
AU - Teysseyre, Sebastien
T2 - 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors
C2 - 2019///
C3 - Proceedings of 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors
CY - Boston, MA
DA - 2019///
PY - 2019/8/11/
ER -
TY - JOUR
TI - Diffusion behaviors between Fe and Pd-containing metallic fuel
AU - Xie, Y.
AU - Benson, M.T.
AU - He, L.
AU - King, J.A.
T2 - Transactions of the American Nuclear Society
DA - 2019/6//
PY - 2019/6//
VL - 120
IS - 1
SP - 412-413
ER -
TY - JOUR
TI - Characterization of U-Pu-Zr alloys with Pd as a minor additive
AU - Benson, M.T.
AU - Xie, Y.
AU - He, L.
AU - King, J.A.
T2 - Transactions of the American Nuclear Society
DA - 2019///
PY - 2019///
VL - 120
ER -
TY - RPRT
TI - Irradiation Testing Strategy for Commercialization of a Molten Chloride Fast Reactor System
AU - Palmer, A.J.
AU - Holbrook, M.R.
AU - Jaoude, A.Abou
AU - Core, G.M.
AU - Cao, G.
AU - Marsden, K.C.
AU - He, L.
AU - Frank, S.M.
AU - Calderoni, P.
DA - 2019///
PY - 2019///
ER -
TY - JOUR
TI - Effect of Ag nanoclusters deposited with magnetron sputtering on laser-induced breakdown spectroscopy enhancement
AU - Shen, J.
AU - Wu, K.
AU - Cao, D.
AU - Wang, J.
AU - Hu, B.
T2 - Spectrochimica Acta - Part B Atomic Spectroscopy
AB - In this paper, we report experimental observation of the influence of Ag nanoclusters growth on nanoparticle enhanced laser-induced breakdown spectroscopy (NELIBS). In this work, we studied changes in the emission intensity of LIBS, on the example of Si I line at the wavelength of 390.55 nm, as a function of the silver nanoclusters coverage. The emission intensity initially increases before beginning to saturate, and then decreases with increasing Ag nanoclusters coverage. The obtained Ag clusters show a red-shifted plasmon resonance peak with increasing cluster coverage. Atomic force microscopy (AFM) was used to provide information changes in the cluster size and shape. Additionally, a 3D finite-difference-time-domain (FDTD) simulation was performed to estimate the electric field enhancement numerically.
DA - 2019///
PY - 2019///
DO - 10.1016/j.sab.2019.05.001
VL - 156
SP - 59-65
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85065176461&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Ionization wave propagation in an atmospheric pressure plasma multi-jet
AU - Lietz, Amanda M
AU - Damany, Xavier
AU - Robert, Eric
AU - Pouvesle, Jean-Michel
AU - Kushner, Mark J
T2 - Plasma Sources Science and Technology
AB - The atmospheric pressure multi-plasma jet produces an array of individual plasma jets which originate from the branching of a single ionization wave (IW). The use of arrays of such plasma jets could enable treatment of larger surface areas than is possible with a single plasma jet. In this paper, we discuss results from a combined experimental and two-dimensional modeling investigation of the behavior of IWs in an atmospheric pressure plasma multi-jet device. In this multi-jet, a rare gas is flowed through a tube having a line of holes, producing gas jets into the ambient from each of the holes. A primary ionization wave (PIW) propagates through the tube which launches a series of secondary ionization waves (SIWs) propagating out each hole through the plumes of the individual gas jets. The propagation of the SIWs is more intense using a positive polarity voltage pulse due to the higher electric field at the ionization front. The diameter of the holes determines the delay of the SIW after passage of the PIW past the hole, with smaller holes resulting in larger delays. The larger delay results from a smaller view angle for photoionization outside the tube from photons originating in the PIW. Higher helium flow rates result in a greater tendency for SIW propagation because the air concentrations in the individual gas jets outside the tube are lower and so the electron temperature is higher. The interaction between SIWs is primarily electrostatic, and is a sensitive function of geometric parameters including proximity of ground planes and the spacing between the holes through which these SIWs emerge.
DA - 2019/12/13/
PY - 2019/12/13/
DO - 10.1088/1361-6595/ab4ab0
VL - 10
UR - https://doi.org/10.1088/1361-6595/ab4ab0
KW - atmospheric pressure plasma jet
KW - ionization waves
KW - multi-jet
KW - modeling
KW - imaging
KW - plasma-surface interactions
ER -
TY - JOUR
TI - Atmospheric pressure plasma activation of water droplets
AU - Kruszelnicki, Juliusz
AU - Lietz, Amanda M
AU - Kushner, Mark J
T2 - Journal of Physics D: Applied Physics
AB - Low temperature plasma treatment of water is being investigated due to its use in pollution abatement, wound treatment and agriculture. Plasma produced reactive oxygen and nitrogen species (RONS) are formed in the gas phase and solvate into the liquid. Activation of the liquid is often limited by transport of these RONS species to the liquid surface. Micrometer scale droplets immersed in the plasma have a large surface to volume ratio (SVR), which increases the interaction area for a given volume of water, and can increase the rates of transport from the gas to liquid. In this paper, results from 0- and 2-dimensional modeling of air-plasma activation of water micro-droplets are discussed. The solvation dynamics are sensitive to the Henry's law constant (h) of each species, which describes its hydrophobicity (low h) or hydrophilicity (high h). The liquid densities of stable species with high h values (e.g. H2O2, HNOx) are sensitive to droplet diameter. For large droplets, hydrophilic species may deplete the gas-phase inventory of RONS before liquid-phase saturation is reached, limiting the total in liquid density for species with high h. For smaller droplets, higher average in-droplet densities of these species can be produced. Liquid concentrations of stable species with low h (e.g. O3, N2O, H2) had a weak dependence on droplet size as droplets are quickly saturated and solvation does not deplete the gas phase. An analysis of this behavior is discussed which represents the well-stirred reactor (0-dimensional) approximation. Spatial non-uniformity of the plasma also has an impact on the solvation rates and kinetics. Gas phase depletion of high-h species leads to a decrease in solvation rates. Low-h species that saturate the surface of the droplets during plasma-on periods can quickly de-solvate in the afterglow.
DA - 2019/8/28/
PY - 2019/8/28/
DO - 10.1088/1361-6463/ab25dc
VL - 5
UR - https://doi.org/10.1088/1361-6463/ab25dc
KW - plasma activation water droplets
KW - plasma chemistry
KW - plasma-water interactions
ER -
TY - JOUR
TI - Plasma kinetics in a nanosecond pulsed filamentary discharge sustained in Ar–H2O and H2O
AU - Luo, Yuchen
AU - Lietz, Amanda M
AU - Yatom, Shurik
AU - Kushner, Mark J
AU - Bruggeman, Peter J
T2 - Journal of Physics D: Applied Physics
DA - 2019/1/23/
PY - 2019/1/23/
DO - 10.1088/1361-6463/aaeb14
VL - 10
UR - https://doi.org/10.1088/1361-6463/aaeb14
KW - plasmas in liquids
KW - chemical kinetics
KW - pulsed plasmas
KW - water vapor
KW - H2O2 production
KW - 0D kinetics modeling
KW - laser induced fluoresence
ER -
TY - JOUR
TI - Atmospheric pressure plasma jets onto a reactive water layer over tissue: pulse repetition rate as a control mechanism
AU - Norberg, Seth A
AU - Parsey, Guy M
AU - Lietz, Amanda M
AU - Johnsen, Eric
AU - Kushner, Mark J
T2 - Journal of Physics D: Applied Physics
AB - The use of plasma jets to treat tissue in the context of plasma medicine often involves a thin intervening liquid layer on top of the tissue. Plasma activated species first transport through and react in the liquid layer prior to reaching the tissue. Of the many parameters that can be used to control this process, pulse repetition frequency (PRF) stands out. Results from a computational investigation of multiple pulses at varying PRF from an atmospheric pressure plasma jet (APPJ) onto a reactive liquid layer are discussed, and three key trends are made clear. First, a high PRF (short time between pulses) enables the gaseous species produced during the previous pulse to remain in the vicinity of the plasma at the onset of the next pulse, thereby increasing the inventory of (H)NxOy and O3 in the gas phase. These species then solvate into the liquid, water in this case, and produce higher densities of aqueous ozone, nitrate, and peroxynitrite. With a lower PRF, reactants produced on a previous pulse are convected away prior to the next discharge pulse with more spatial separation of reactants both above and within the water. As a result, more of the hydroxyl anion (), ozone anion () and nitric oxide (NOaq) reach the tissue beneath the water. The second trend is that the production of H2O2aq and its fluence to the underlying tissue are relatively independent of the PRF. The precursors for H2O2aq are primarily produced by the surface ionization wave (SIW) on the top of the liquid, which then directly solvate into the liquid. Lastly, when the plasma plume touches the liquid, the SIW on the water layer increases the production of all aqueous species compared to configurations where the plasma plume does not touch the liquid. These trends are true for all PRF.
DA - 2019/1/2/
PY - 2019/1/2/
DO - 10.1088/1361-6463/aae41e
VL - 9
UR - https://doi.org/10.1088/1361-6463/aae41e
KW - atmospheric pressure plasma jet
KW - plasma-liquid interactions
KW - modeling
KW - plasma medicine
KW - control mechanisms
ER -
TY - RPRT
TI - Eutectoid Transformation in U10Mo Alloy: Effect of Deformation History and Homogenization Heat Treatment
AU - Jana, Saumyadeep
AU - Schemer-Kohrn, Alan L.
AU - Overman, Nicole R.
AU - Sweet, Lucas E.
AU - Kautz, Elizabeth J.
AU - Lavender, Curt A.
AU - Joshi, Vineet V.
A3 - Office of Scientific and Technical Information (OSTI)
AB - In the United States, uranium 10 wt.% molybdenum (U10Mo) alloy has been selected as the nuclear fuel that will be used when transitioning research reactors and radioisotope production facilities from highly enriched uranium (>85% 235U) fuel to low-enriched uranium (<20% 235U) fuel. The fabrication steps for producing U10Mo fuel foil involve multiple hot-rolling/cold-rolling/intermediate annealing steps. The U10Mo alloy, which can retain the desirable high-temperature body-centered cubic γ-U (A2) structure at room temperature as a metastable phase for optimum in-reactor performance, goes through a eutectoid reaction below ~560°C and forms a-U as a reaction product, which is highly undesirable. Because the fabrication steps are carried out in the temperature range of 500 to 700°C, it is critical to understand the eutectoid reaction kinetics as a function of rolling/annealing steps. In this study, we determined the eutectoid transformation behavior of various rolled/annealed U10Mo coupons at 450, 500, and 525°C. The results show that the highest degree of phase transformation occurs when the U10Mo billet is rolled down from the as-cast condition without any prior homogenization treatment. Further, we observed that mechanical deformation (in the form of hot-rolling/cold-rolling) leads to increased eutectoid transformation compared to the billets that were not deformed.
DA - 2019/1/31/
PY - 2019/1/31/
DO - 10.2172/1503687
PB - Office of Scientific and Technical Information (OSTI)
UR - http://dx.doi.org/10.2172/1503687
DB - Crossref
ER -
TY - JOUR
TI - Exploring New Science Domains with Atom Probe Tomography Enabled by an Environmental Transfer Hub
AU - Perea, Daniel E.
AU - Schreiber, Daniel K.
AU - Devaraj, Arun
AU - Reilly, Dallas D.
AU - Lambeets, Sten V.
AU - Kautz, Elizabeth J.
AU - Lach, Timothy G.
AU - Wirth, Mark G.
AU - Evans, James E.
T2 - Microscopy and Microanalysis
DA - 2019/8//
PY - 2019/8//
DO - 10.1017/s1431927619002113
VL - 25
IS - S2
SP - 276-277
J2 - Microsc Microanal
LA - en
OP -
SN - 1431-9276 1435-8115
UR - http://dx.doi.org/10.1017/s1431927619002113
DB - Crossref
ER -
TY - JOUR
TI - Multimodal Atomic Scale Characterization of Structural and Compositional Changes During Shear Deformation of Materials
AU - Gwalani, Bharat
AU - Kautz, Elizabeth J.
AU - Kaspar, Tiffany
AU - Kovarik, Libor
AU - Joshi, Vineet V.
AU - Mathaudhu, Suveen
AU - Rohatgi, Aashish
AU - Sushko, Peter
AU - Devaraj, Arun
T2 - Microscopy and Microanalysis
DA - 2019/8//
PY - 2019/8//
DO - 10.1017/s143192761901328x
VL - 25
IS - S2
SP - 2510-2511
J2 - Microsc Microanal
LA - en
OP -
SN - 1431-9276 1435-8115
UR - http://dx.doi.org/10.1017/s143192761901328x
DB - Crossref
ER -
TY - JOUR
TI - Enhanced Catalyst Durability for Bio-Based Adipic Acid Production by Atomic Layer Deposition
AU - Settle, Amy E.
AU - Cleveland, Nicholas S.
AU - Farberow, Carrie A.
AU - Conklin, Davis R.
AU - Huo, Xiangchen
AU - Dameron, Arrelaine A.
AU - Tracy, Ryon W.
AU - Sarkar, Reuben
AU - Kautz, Elizabeth J.
AU - Devaraj, Arun
AU - Ramasamy, Karthikeyan K.
AU - Watson, Mike J.
AU - York, Allyson M.
AU - Richards, Ryan M.
AU - Unocic, Kinga A.
AU - Beckham, Gregg T.
AU - Griffin, Michael B.
AU - Hurst, Katherine E.
AU - Tan, Eric C.D.
AU - Christensen, Steven T.
AU - Vardon, Derek R.
T2 - Joule
AB - Atomic layer deposition (ALD) improves the durability of metal catalysts using nanoscale metal oxide coatings. However, targeted coating strategies and economic models are lacking for process-specific deactivation challenges that account for implications at scale. Herein, we apply Al2O3 ALD to Pd/TiO2 to increase durability during hydrogenation of muconic acid, a bio-based platform chemical, to adipic acid. Initial coating development and characterization are performed on the milligram scale using stop-flow ALD. Subsequently, ALD coating scale is increased by 3 orders of magnitude using fluidized bed ALD. Activity, leaching resistance, and thermal stability are evaluated at each synthesis scale. ALD-coated catalysts retain up to 2-fold greater muconic acid hydrogenation activity and undergo significantly less physical restructuring than uncoated Pd/TiO2 after high-temperature treatments, while reducing Pd leaching by over 4-fold. Techno-economic analysis for an adipic acid biorefinery supports increased ALD material costs through catalyst lifetime extension, underscoring the potential viability of this technology.
DA - 2019/9//
PY - 2019/9//
DO - 10.1016/j.joule.2019.06.022
VL - 3
IS - 9
SP - 2219-2240
J2 - Joule
LA - en
OP -
SN - 2542-4351
UR - http://dx.doi.org/10.1016/j.joule.2019.06.022
DB - Crossref
ER -
TY - CONF
TI - Atomic Layer Deposition to Extend Catalyst Lifetime for Biobased Adipic Acid Production-Application and Scale-up Considerations
AU - Settle, A.
AU - Cleveland, N.
AU - Huo, X.
AU - York, A.
AU - Farberow, C.
AU - Kautz, E.
AU - Deavaraj, A.
AU - Ramasamy, K.
AU - Richards, R.
AU - Unocic, K.A.
AU - Beckham, G.T.
AU - Griffin, M.B.
AU - Hurst, K.
AU - Tan, E.
AU - Christensen, S.
AU - Vardon, D.
T2 - 2019 North American Catalysis Society Meeting
C2 - 2019///
C3 - 2019 North American Catalysis Society Meeting
CY - Chicago, Illinois
DA - 2019///
PY - 2019/6/23/
ER -
TY - JOUR
TI - Direct Observation of Zirconium Alloy Oxidation at the Nanoscale
AU - Kautz, Elizabeth
AU - Lambeets, Sten
AU - Gwalani, Bharat
AU - Kovarik, Libor
AU - Perea, Daniel
AU - Devaraj, Arun
T2 - Microscopy and Microanalysis
AB - Journal Article Direct Observation of Zirconium Alloy Oxidation at the Nanoscale Get access Elizabeth Kautz, Elizabeth Kautz National Security Directorate, Pacific Northwest National Laboratory, Richland, WA Search for other works by this author on: Oxford Academic Google Scholar Sten Lambeets, Sten Lambeets Earth & Biological Sciences, Pacific Northwest National Laboratory, Richland, WA Search for other works by this author on: Oxford Academic Google Scholar Bharat Gwalani, Bharat Gwalani Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA Search for other works by this author on: Oxford Academic Google Scholar Libor Kovarik, Libor Kovarik Earth & Biological Sciences, Pacific Northwest National Laboratory, Richland, WA Search for other works by this author on: Oxford Academic Google Scholar Daniel Perea, Daniel Perea Earth & Biological Sciences, Pacific Northwest National Laboratory, Richland, WA Search for other works by this author on: Oxford Academic Google Scholar Arun Devaraj Arun Devaraj Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA Corresponding author: arun.devaraj@pnnl.gov Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 25, Issue S2, 1 August 2019, Pages 318–319, https://doi.org/10.1017/S1431927619002320 Published: 01 August 2019
DA - 2019/8//
PY - 2019/8//
DO - 10.1017/s1431927619002320
VL - 25
IS - S2
SP - 318-319
J2 - Microsc Microanal
LA - en
OP -
SN - 1431-9276 1435-8115
UR - http://dx.doi.org/10.1017/s1431927619002320
DB - Crossref
ER -
TY - JOUR
TI - Influence of Composition and Structure on Measured H Concentration in beta-Ti Alloys via Atom Probe Tomography
AU - Ballor, JoAnn
AU - Kautz, Elizabeth
AU - Gwalani, Bharat
AU - Boehlert, Carl
AU - Devaraj, Arun
T2 - Microscopy and Microanalysis
DA - 2019/8//
PY - 2019/8//
DO - 10.1017/s1431927619013448
VL - 25
IS - S2
SP - 2542-2543
J2 - Microsc Microanal
LA - en
OP -
SN - 1431-9276 1435-8115
UR - http://dx.doi.org/10.1017/s1431927619013448
DB - Crossref
ER -
TY - JOUR
TI - Comprehensive Analysis of Hydrogen, Deuterium, Tritium and Isotopic Ratios of Other Light Elements in Neutron Irradiated TPBAR Components
AU - Devaraj, Arun
AU - Matthews, Bethany
AU - Arey, Bruce
AU - Kautz, Elizabeth
AU - Sevigny, Gary
AU - Senor, David
T2 - Microscopy and Microanalysis
AB - Journal Article Comprehensive Analysis of Hydrogen, Deuterium, Tritium and Isotopic Ratios of Other Light Elements in Neutron Irradiated TPBAR Components Get access Arun Devaraj, Arun Devaraj Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA Corresponding author: arun.devaraj@pnnl.gov Search for other works by this author on: Oxford Academic Google Scholar Bethany Matthews, Bethany Matthews Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA, USA Search for other works by this author on: Oxford Academic Google Scholar Bruce Arey, Bruce Arey Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA, USA Search for other works by this author on: Oxford Academic Google Scholar Elizabeth Kautz, Elizabeth Kautz National Security Directorate, Pacific Northwest National Laboratory, Richland, WA, USA Search for other works by this author on: Oxford Academic Google Scholar Gary Sevigny, Gary Sevigny Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA, USA Search for other works by this author on: Oxford Academic Google Scholar David Senor David Senor Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 25, Issue S2, 1 August 2019, Pages 280–281, https://doi.org/10.1017/S1431927619002137 Published: 01 August 2019
DA - 2019/8//
PY - 2019/8//
DO - 10.1017/s1431927619002137
VL - 25
IS - S2
SP - 280-281
J2 - Microsc Microanal
LA - en
OP -
SN - 1431-9276 1435-8115
UR - http://dx.doi.org/10.1017/s1431927619002137
DB - Crossref
ER -
TY - JOUR
TI - Nanoscale Spatially Resolved Mapping of Uranium Enrichment
AU - Kautz, Elizabeth
AU - Burkes, Douglas
AU - Joshi, Vineet
AU - Lavender, Curt
AU - Devaraj, Arun
T2 - Scientific Reports
AB - Abstract Spatially resolved analysis of uranium (U) isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving subnanometer-scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography—a three-dimensional nanoscale characterisation technique—we demonstrate unprecedented nanoscale mapping of U isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (~100 nm 3 ) of depleted and low-enriched U alloyed with 10 wt% molybdenum that has different nominal enrichments of 0.20 and 19.75% 235 U, respectively. We map enrichment in various morphologies of a U carbide phase, the adjacent γ-UMo matrix, and across interfaces (e.g., carbide/matrix, grain boundary). Results indicate the U carbides were formed during casting, rather than retained from either highly enriched or depleted U feedstock materials. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origins and thermomechanical processing routes.
DA - 2019/8/23/
PY - 2019/8/23/
DO - 10.1038/s41598-019-48479-5
VL - 9
IS - 1
J2 - Sci Rep
LA - en
OP -
SN - 2045-2322
UR - http://dx.doi.org/10.1038/s41598-019-48479-5
DB - Crossref
ER -
TY - JOUR
TI - Nanoscale Spatially Resolved Mapping of Uranium Enrichment in Actinide-Bearing Materials
AU - Kautz, Elizabeth
AU - Lach, Timothy
AU - Reilly, Dallas
AU - Joshi, Vineet
AU - Lavender, Curt
AU - Devaraj, Arun
T2 - Microscopy and Microanalysis
AB - Spatially resolved analysis of uranium isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving sub-nanometer scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography, a three dimensional nanoscale characterization technique, we demonstrate unprecidented nanoscale mapping of uranium isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (100 nm3) of depleted and low enriched uranium alloyed with 10 wt % molybdenum with different nominal enrichments of 0.20 and 19.75% 235U respectively. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origin and thermo-mechanical processing routes.
DA - 2019/8//
PY - 2019/8//
DO - 10.1017/s1431927619013321
VL - 25
IS - S2
SP - 2518-2519
J2 - Microsc Microanal
LA - en
OP -
SN - 1431-9276 1435-8115
UR - http://dx.doi.org/10.1017/s1431927619013321
DB - Crossref
ER -
TY - JOUR
TI - Composition-Dependent Microstructure-Property Relationships of Fe and Al Modified Ti-12Cr (wt.%)
AU - Ballor, J.
AU - Ikeda, M.
AU - Kautz, E. J.
AU - Boehlert, C. J.
AU - Devaraj, A.
T2 - JOM
DA - 2019/4/15/
PY - 2019/4/15/
DO - 10.1007/s11837-019-03467-y
VL - 71
IS - 7
SP - 2321-2330
J2 - JOM
LA - en
OP -
SN - 1047-4838 1543-1851
UR - http://dx.doi.org/10.1007/s11837-019-03467-y
DB - Crossref
ER -
TY - JOUR
TI - A machine learning approach to thermal conductivity modeling: A case study on irradiated uranium-molybdenum nuclear fuels
AU - Kautz, Elizabeth J.
AU - Hagen, Alexander R.
AU - Johns, Jesse M.
AU - Burkes, Douglas E.
T2 - Computational Materials Science
AB - A deep neural network was developed for the purpose of predicting thermal conductivity with a case study performed on neutron irradiated nuclear fuel. Traditional thermal conductivity modeling approaches rely on existing theoretical frameworks that describe known, relevant phenomena that govern the microstructural evolution processes during neutron irradiation (such as recrystallization, and pore size, distribution and morphology). Current empirical modeling approaches, however, do not represent all irradiation test data well. Here, we develop a machine learning approach to thermal conductivity modeling that does not require a priori knowledge of a specific material microstructure and system of interest. Our approach allows researchers to probe dependency of thermal conductivity on a variety of reactor operating and material conditions. The purpose of building such a model is to allow for improved predictive capabilities linking structure-property-processing-performance relationships in the system of interest (here, irradiated nuclear fuel), which could lead to improved experimental test planning and characterization. The uranium-molybdenum system is the fuel system studied in this work, and historic irradiation test data is leveraged for model development. Our model achieved a mean absolute percent error of approximately 4% for the validation data set (when a leave-one-out cross validation approach was applied). Results indicate our model generalizes well to never before seen data, and thus use of deep learning methods for material property predictions from limited, historic irradiation test data is a viable approach. This work is at the frontier of the evolving paradigm in materials science, where machine learning methods are being applied to material property predictions in lieu of limited experimental data fitted to low-dimensionality phenomenological models. The work presented here aims to demonstrate the potential and limitations of machine learning in the field of materials science and material property modeling.
DA - 2019/4//
PY - 2019/4//
DO - 10.1016/j.commatsci.2019.01.044
VL - 161
SP - 107-118
J2 - Computational Materials Science
LA - en
OP -
SN - 0927-0256
UR - http://dx.doi.org/10.1016/j.commatsci.2019.01.044
DB - Crossref
KW - Machine learning
KW - Deep learning
KW - Neural network
KW - Multi-layer perceptron network
KW - Material property prediction
KW - Thermal conductivity
KW - Nuclear fuel performance
KW - U-Mo
KW - Post irradiation examination
KW - Low-enriched uranium
ER -
TY - JOUR
TI - Time-resolved imaging of atoms and molecules in laser-produced uranium plasmas
AU - Kautz, E. J.
AU - Skrodzki, P. J.
AU - Burger, M.
AU - Bernacki, B. E.
AU - Jovanovic, I.
AU - Phillips, M. C.
AU - Harilal, S. S.
T2 - Journal of Analytical Atomic Spectrometry
AB - Spatial temporal contours of atoms and molecules in uranium plasmas reveal complex plasma–chemical interaction between plume and oxygen-containing ambient gas.
DA - 2019///
PY - 2019///
DO - 10.1039/C9JA00228F
VL - 34
IS - 11
SP - 2236-2243
UR - https://doi.org/10.1039/C9JA00228F
ER -
TY - JOUR
TI - Physical conditions for UO formation in laser-produced uranium plumes
AU - Harilal, S. S.
AU - Kautz, E. J.
AU - Bernacki, B. E.
AU - Phillips, M. C.
AU - Skrodzki, P. J.
AU - Burger, M.
AU - Jovanovic, I.
T2 - Physical Chemistry Chemical Physics
AB - We investigate the oxidation of uranium (U) species, the physical conditions leading to uranium monoxide (UO) formation and the interplay between plume hydrodynamics and plasma chemistry in a laser-produced U plasma. Plasmas are produced by ablation of metallic U using nanosecond laser pulses. An ambient gas environment with varying oxygen partial pressures in 100 Torr inert Ar gas is used for controlling the plasma oxidation chemistry. Optical emission spectroscopic analysis of U atomic and monoxide species shows a reduction in the emission intensity and persistence with increasing oxygen partial pressure. Spectral modelling is used for identifying the physical conditions in the plasma that favor UO formation. The optimal temperature for UO formation is found to be in the temperature range of ∼1500-5000 K. The spectrally integrated and spectrally filtered (monochromatic) imaging of U atomic and molecular species reveals the evolutionary paths of various species in the plasma. Our results also highlight that oxidation in U plasmas predominantly occurs at the cooler periphery and is delayed with respect to plasma formation, and the dissipation of molecular species strongly depends on oxygen partial pressure.
DA - 2019///
PY - 2019///
DO - 10.1039/C9CP02250C
VL - 21
IS - 29
SP - 16161-16169
UR - https://doi.org/10.1039/C9CP02250C
ER -
TY - JOUR
TI - Microstructure and microchemistry study of irradiation-induced precipitates in proton irradiated ZrNb alloys
AU - Yu, Zefeng
AU - Zhang, Chenyu
AU - Voyles, Paul M.
AU - He, Lingfeng
AU - Liu, Xiang
AU - Nygren, Kelly
AU - Couet, Adrien
T2 - Acta Materialia
AB - Proton irradiation induced Nb redistribution in Zr-xNb alloys (x = 0.4, 0.5, 1.0 wt%) has been investigated using scanning transmission electron microscopy/energy dispersive X-ray spectroscopy (STEM/EDS). Zr-xNb alloys are mainly composed of Zr matrix, native Zr–Nb–Fe phases, and β-Nb precipitates. After 2 MeV proton irradiation at 350 °C, a decrease of Nb content in native precipitates, as well as irradiation-induced precipitation of Nb-rich platelets (135 ± 69 nm long and 27 ± 12 nm wide) were found. Nb-rich platelets and Zr matrix form the Burgers orientation relationship, [11¯1]//[21¯1¯0] and (011)//(0002). The platelets were found to be mostly coherent with the matrix with a few dislocations near the ends of the precipitate. The coherent strain field has been measured in the matrix and platelets by the 4D-STEM technique. The growth of Nb-rich platelets is mainly driven by coherency and dislocation-induced strain fields. Irradiation may both enhance the diffusion and induce segregation of interstitial Nb to the ends of the irradiation induced platelets, further facilitating their growth.
DA - 2019/10//
PY - 2019/10//
DO - 10.1016/j.actamat.2019.08.012
UR - https://doi.org/10.1016/j.actamat.2019.08.012
KW - Irradiation
KW - Microstructure
KW - ZrNb
ER -
TY - JOUR
TI - Microstructural characterization of annealed U-20Pu-10Zr-3.86Pd and U-20Pu-10Zr-3.86Pd-4.3Ln
AU - Benson, Michael T.
AU - Xie, Yi
AU - He, Lingfeng
AU - Tolman, Kevin R.
AU - King, James A.
AU - Harp, Jason M.
AU - Mariani, Robert D.
AU - Hernandez, Brandon J.
AU - Murray, Daniel J.
AU - Miller, Brandon D.
T2 - Journal of Nuclear Materials
AB - Palladium is being investigated as a potential additive to metallic fuel to bind fission product lanthanides, with the goal of reducing or preventing fuel-cladding chemical interactions (FCCI). A primary cause of FCCI is the lanthanide fission products moving to the fuel periphery and interacting with the cladding. This interaction will lead to wastage of the cladding and eventually to a cladding breach. The current study is the microstructural characterization of annealed U-20Pu-10Zr-3.86Pd and U-20Pu-10Zr-3.86Pd-4.3Ln in wt. %, where Ln = 53Nd-25Ce-16Pr-6La, using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In both alloys, the matrix is comprised of ζ-U0.4Pu0.6 and δ-(U,Pu)Zr2. Based on the matrix compositions, modifications to the room temperature extrapolated U-Pu-Zr ternary phase diagram are suggested. In U-20Pu-10Zr-3.86Pd, there is very little δ phase, due to formation of PdZr2. In U-20Pu-10Zr-3.86Pd-4.3Ln, a lanthanide-rich phase is present, although it does not have the crystal structure for 53Nd-25Ce-16Pr-6La. This phase cannot be identified based on known compounds. (Ln,Pu)Pd is the primary lanthanide phase, with Pu substituting into the crystal structure in place of Nd.
DA - 2019/5//
PY - 2019/5//
DO - 10.1016/j.jnucmat.2019.03.014
VL - 518
SP - 287-297
UR - https://doi.org/10.1016/j.jnucmat.2019.03.014
KW - Metallic fuel
KW - FCCI
KW - Fuel additive
KW - Transmutation fuel
ER -
TY - JOUR
TI - Self-healing behavior and strength recovery of ytterbium disilicate ceramic reinforced with silicon carbide nanofillers
AU - Nguyen, Son Thanh
AU - Nakayama, Tadachika
AU - Suematsu, Hisayuki
AU - Iwasawa, Hirokazu
AU - Suzuki, Tsuneo
AU - Otsuka, Yuichi
AU - He, Lingfeng
AU - Takahashi, Tsuyoshi
AU - Niihara, Koichi
T2 - Journal of the European Ceramic Society
AB - Environmental barrier coatings (EBCs) are necessary to protect SiC/SiC ceramic components against oxidation and hot corrosion in high-temperature applications. The volatilization of SiO2 in SiC-reinforced materials is a major obstacle for the implementation of these self-crack-healing ceramics. The Yb2Si2O7-Yb2SiO5-SiC composite is known as a self-healing material that can help to avoid this SiC recession. In this research, the crack-healing behavior of this composite is investigated by using pre-cracking followed by annealing in an oxidizing environment. The crack-healing mechanism is explored and elucidated as a function of the filler morphology, crack size, annealing time, and annealing temperature. The two main crack-healing mechanisms are the filling of cracks with SiO2 glass and the volume expansion of Yb2Si2O7 induced by the reaction between SiO2 and Yb2SiO5. Full crack recovery is achieved with only 10 vol% SiC, with evidence from XRD and EDS analyses. SiC nanoparticulates are more efficient fillers than nanofibers and nanowhiskers.
DA - 2019/8//
PY - 2019/8//
DO - 10.1016/j.jeurceramsoc.2019.03.040
VL - 39
IS - 10
SP - 3139-3152
J2 - Journal of the European Ceramic Society
LA - en
OP -
SN - 0955-2219
UR - http://dx.doi.org/10.1016/j.jeurceramsoc.2019.03.040
DB - Crossref
KW - Crack-healing
KW - Silicon carbide
KW - Ceramic
KW - Ytterbium silicate
KW - Nanofiller
ER -
TY - JOUR
TI - Diffusion Behavior between Metallic Fuel Alloys with Pd Addition and Fe
AU - Xie, Y.
AU - Benson, M.T.
AU - He, L.
AU - King, J.A.
AU - Mariani, R.D.
AU - Murray, D.J.
T2 - Journal of Nuclear Materials
AB - Fission product lanthanides in metallic fuels are known to cause adverse fuel-cladding chemical interaction (FCCI). Palladium (Pd) is being explored as a potential additive to reduce or mitigate FCCI by forming stable Pd-Ln compounds. The current study is an investigation of diffusion behaviors between UZrPd, UZrPdLn, UPuZrPd, and UPuZrPdLn alloys (Ln = 53Nd-25Ce-16Pr-6La wt. %) and iron (Fe). Diffusion couple tests were performed followed by microstructural analysis using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is found that the diffusion of Fe into the fuel is reduced by PdZr2 precipitates randomly dispersed throughout the fuel matrix. Ln-Pd compounds form in UZrPdLn alloys, and (Ln,Pu)Pd forms in the UPuZrPdLn alloy. In both diffusion couples with Ln, small amounts of lanthanides are diffusing into the Fe. This could be due to small amounts of dissolved lanthanides in the precipitates, or could be due to the Ln-Pd compounds decomposing. In either case, diffusion caused by lanthanides is greatly reduced as compared to alloys without Pd.
DA - 2019/11//
PY - 2019/11//
DO - 10.1016/j.jnucmat.2019.07.028
VL - 525
SP - 111-124
UR - http://dx.doi.org/10.1016/j.jnucmat.2019.07.028
KW - Fuel-cladding chemical interaction
KW - Fuel additive
KW - Diffusion
KW - Metallic fuel
ER -
TY - JOUR
TI - Impact of irradiation induced dislocation loops on thermal conductivity in ceramics
AU - Khafizov, Marat
AU - Pakarinen, Janne
AU - He, Lingfeng
AU - Hurley, David H.
T2 - Journal of the American Ceramic Society
AB - Abstract Experimental work aimed at understanding the role of dislocation loops in limiting phonon mediated thermal transport in ceramics is presented. Faulted dislocation loops, having diameters of a few nanometers, were introduced by irradiating a polycrystalline cerium dioxide sample with 1.6 MeV protons at 700°C. XRD analysis indicated that irradiated samples retained their crystalline structure and exhibit very little lattice expansion suggesting a low concentration of point defects. Further microstructure characterization using transmission electron microscopy revealed that interstitial type faulted dislocation loops were primarily created as expected for these irradiation conditions. Thermal conductivity of the damaged layer was measured using a modulated thermoreflectance approach. Analysis of the experimental data using the classical Klemens‐Callaway approach reveals that the conductivity reduction is primarily due to dislocation loops, while point defects and voids play only a minor role. These results provide experimental confirmation that faulted loops offer a unique arrangement for displaced atoms that leads to an unusually large reduction of thermal conductivity.
DA - 2019/12//
PY - 2019/12//
DO - 10.1111/jace.16616
VL - 102
IS - 12
SP - 7533-7542
UR - https://doi.org/10.1111/jace.16616
KW - dislocation loops
KW - radiation damage
KW - thermal conductivity
ER -
TY - JOUR
TI - A simple way to make pre-stressed ceramics with high strength
AU - Bao, Yiwang
AU - Kuang, Fenghua
AU - Sun, Yi
AU - Li, Yueming
AU - Wan, Detian
AU - Shen, Zongyang
AU - Ma, Delong
AU - He, Lingfeng
T2 - Journal of Materiomics
AB - A pre-stressing design and a simple fabrication technology to substantially improve the strength of ceramic components are presented. Residual surface compressive stress is generated in ceramic components by pressureless sintering of a green bulk coated with a thin layer of low coefficient of thermal expansion (CTE). The stress level can be controlled by changing the cross-section area ratio, Young's modulus ratio and CTE ratio of the coating. Pre-stressed ZrO2 ceramics coated with Al2O3 can achieve a flexural strength of 1330 ± 52 MPa, 45% higher than their uncoated counterpart. Similarly, the flexural strength of building porcelain tiles is increased by 70%, from 67 ± 3 MPa to 114 ± 5 MPa. The damage tolerance of pre-stressed ZrO2 ceramics is excellent with a high residual strength of ∼1200 MPa in a thermal shock test at 325 °C. This simple technique can improve the mechanical performance of ceramic components with no limitation of size and shape.
DA - 2019/12//
PY - 2019/12//
DO - 10.1016/j.jmat.2019.06.001
VL - 5
IS - 4
SP - 657-662
J2 - Journal of Materiomics
LA - en
OP -
SN - 2352-8478
UR - http://dx.doi.org/10.1016/j.jmat.2019.06.001
DB - Crossref
KW - Pre-stressed ceramics
KW - Coating
KW - Strength
KW - Thermal shock resistance
ER -
TY - JOUR
TI - On the ion and electron temperature recovery after the ELM-crash at ASDEX upgrade
AU - Cavedon, M.
AU - Dux, R.
AU - Pütterich, T.
AU - Viezzer, E.
AU - Wolfrum, E.
AU - Dunne, M.
AU - Fable, E.
AU - Fischer, R.
AU - Harrer, G.F.
AU - Laggner, F.M.
AU - Mink, A.F.
AU - Plank, U.
AU - Stroth, U.
AU - Willensdorfer, M.
AU - Team, ASDEX Upgrade
T2 - Nuclear Materials and Energy
AB - The access to fast measurements, i.e. Δt ≈ 100 µs, of the ions and the electrons during an entire edge localized cycle (ELM) reveals asymmetries in the recovery of the maximum edge gradients. Different magnetic fluctuations are found to correlate with the saturation of the edge ion temperature (Ti), electrons temperature (Te) and density (ne) gradients. In particular, while ∇Ti and ∇ne clamp roughly 3.0 ms after the ELM-crash together with the onset of mid-frequency (f ≲ 50 kHz) magnetic fluctuations, ∇Te recovers to the pre-ELM conditions only after 7.0 ms and saturates with the appearance of high frequency fluctuations (f ≈ 200 kHz). The effect of electron temperature gradient modes (ETGs) and of energy losses induced by ionization of neutrals are discussed as possible reasons for the delayed recovery of ∇Te. The onset and the suppression of ETGs qualitatively follow the requirements of an increased electron heat transport. However, gyro-kinetic simulations are necessary to quantify the impact of ETGs. On the other hand, the impact of the neutral ionization during the density build-up as an electron energy loss channel is measured to be small compared to the total electron energy. The dominant terms in the electron energy balance are instead the radiative power and the ion-electron heat exchange.
DA - 2019/1//
PY - 2019/1//
DO - 10.1016/j.nme.2018.12.034
VL - 18
SP - 275-280
UR - https://doi.org/10.1016/j.nme.2018.12.034
KW - ELM
KW - Ion temperature
KW - ETG
KW - Neutral ionization
KW - Fast Charge Exchange
ER -
TY - JOUR
TI - Observation of divertor currents during type-I ELMs on the DIII-D tokamak
AU - Knolker, M.
AU - Evans, T.E.
AU - Wingen, A.
AU - Bortolon, A.
AU - Chrystal, C.
AU - Laggner, F.
AU - Moyer, R.A.
AU - Nazikian, R.
AU - Zohm, H.
T2 - Nuclear Materials and Energy
AB - In DIII-D, large currents flowing into the divertor floor during edge-localized modes (ELMs) have been measured by an array of shunt current resistors before an increase of heat flux is measured by IR thermography. The diagnostic consists of 40 tiles distributed in five concentric circles in the lower divertor with sampling rates range between 50 and 500 kHz. Typically, the current measured by a single tile during an ELM can reach 500 A. This amounts to 5–25 kA flowing in the divertor tiles. The temporal evolution of the ELM currents shows a first phase with large amplitude oscillations, occurring before the heat flux increase measured by infrared thermography at the same location, lasting between 0.05 ms and 0.3 ms. A second phase follows where the time evolution of the divertor current mimics the evolution of the divertor heat flux. These currents could affect the plasma edge stability in the nonlinear ELM phase and provide a mechanism leading to explosive growth of edge stochasticity, the need of which and existence is predicted in contemporary nonlinear ELM simulations.
DA - 2019/1//
PY - 2019/1//
DO - 10.1016/j.nme.2019.01.003
VL - 18
SP - 222-226
UR - https://doi.org/10.1016/j.nme.2019.01.003
ER -
TY - JOUR
TI - Inter-ELM pedestal localized fluctuations in tokamaks: Summary of multi-machine observations
AU - Laggner, F.M.
AU - Diallo, A.
AU - Cavedon, M.
AU - Kolemen, E.
T2 - Nuclear Materials and Engergy
AB - A variety of experimental studies on pedestal localized fluctuations appearing in between crashes of edge localized modes (ELMs) across several tokamaks have been reviewed and summarized. The onset of the inter-ELM fluctuations is correlated with the evolution of the pedestal gradients. Three profile recovery phases are extracted, which are interlinked with the onsets of different kinds of pedestal fluctuations. Across machines it is found that the pedestal fluctuations can be assorted into at least three categories. These are determined by the fluctuation onset in the ELM cycle, observed frequency range and radial location in the pedestal. Further, the categories might be also related to different instabilities. Similar observations at various machines may point to a underlying generation mechanism that acts similarly for presently accessible pedestal parameter ranges.
DA - 2019/5//
PY - 2019/5//
DO - 10.1016/j.nme.2019.02.030
VL - 19
SP - 479-486
UR - http://dx.doi.org/10.1016/j.nme.2019.02.030
KW - Plasma
KW - High confinement mode (H-mode)
KW - Edge localized mode (ELM)
KW - Pedestal profiles
KW - Edge instabilities
ER -
TY - JOUR
TI - High fusion performance in Super H-mode experiments on Alcator C-Mod and DIII-D
AU - Snyder, P.B.
AU - Hughes, J.W.
AU - Osborne, T.H.
AU - Paz-Soldan, C.
AU - Solomon, W.M.
AU - Knolker, M.
AU - Eldon, D.
AU - Evans, T.
AU - Golfinopoulos, T.
AU - Grierson, B.A.
AU - Groebner, R.J.
AU - Hubbard, A.E.
AU - Kolemen, E.
AU - Labombard, B.
AU - Laggner, F.M.
AU - Meneghini, O.
AU - Mordijck, S.
AU - Petrie, T.
AU - Scott, S.
AU - Wang, H.Q.
AU - Wilson, H.R.
AU - Zhu, Y.B.
T2 - Nuclear Fusion
AB - Abstract The ‘Super H-Mode’ regime is predicted to enable pedestal height and fusion performance substantially higher than standard H-Mode operation. This regime exists due to a bifurcation of the pedestal pressure, as a function of density, that is predicted by the EPED model to occur in strongly shaped plasmas above a critical pedestal density. Experiments on Alcator C-Mod and DIII-D have achieved access to the Super H-Mode (and Near Super H) regime, and obtained very high pedestal pressure, including the highest achieved on a tokamak ( p ped ~ 80 kPa) in C-Mod experiments operating near the ITER magnetic field. DIII-D Super H experiments have demonstrated strong performance, including the highest stored energy in the present configuration of DIII-D ( W ~ 2.2–3.2 MJ), while utilizing only about half of the available heating power ( P heat ~ 7–12 MW). These DIII-D experiments have obtained the highest value of peak fusion gain, Q DT,equiv ~ 0.5, achieved on a medium scale ( R < 2 m) tokamak. Sustained high performance operation ( β N ~ 2.9, H 98 ~ 1.6) has been achieved utilizing n = 3 magnetic perturbations for density and impurity control. Pedestal and global confinement has been maintained in the presence of deuterium and nitrogen gas puffing, which enables a more radiative divertor condition. A pair of simple performance metrics is developed to assess and compare regimes. Super H-Mode access is predicted for ITER and expected, based on both theoretical prediction and observed normalized performance, to allow ITER to achieve its goals ( Q = 10) at I p < 15 MA, and to potentially enable more compact, cost effective pilot plant and reactor designs.
DA - 2019///
PY - 2019///
DO - 10.1088/1741-4326/ab235b
VL - 59
IS - 8
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85070818533&partnerID=MN8TOARS
KW - pedestal
KW - tokamak
KW - fusion gain
KW - Super H Mode
KW - EPED
KW - DIII-D
KW - Alcator C-Mod
ER -
TY - JOUR
TI - Development of Real-Time Software for Thomson Scattering Analysis at NSTX-U
AU - Rozenblat, R.
AU - Kolemen, E.
AU - Laggner, F.M.
AU - Freeman, C.
AU - Tchilinguirian, G.
AU - Sichta, P.
AU - Zimmer, G.
T2 - Fusion Science and Technology
AB - The Thomson scattering (TS) diagnostic on the National Spherical Tokamak eXperiment Upgrade (NSTX-U) has been an essential system for many operational campaigns due to its function of measuring plasma electron density and temperature. Constructive feedback to improve the next plasma discharge, however, has been limited because of in-between shots analysis. Plasma control, therefore, desires a diagnostic system that is real-time capable. This contribution presents the development of software that demonstrates the feasibility of a real-time TS diagnostic system for NSTX-U. The developed software is able to evaluate the electron temperature and density within 2.5 ms.The overall system requirement is specified by a 60-Hz timing cycle, which is driven by the TS laser pulse rate. The real-time software processes the peak amplitudes of the detected photons, evaluates the electron temperature and density, and then outputs them to an analog output card that is used to interface with the NSTX-U control. The real-time software is implemented in an object-oriented architecture using C++11. C++11 software components include Abstract class, Atomic data types for synchronization, and a Hash data structure. The software application makes use of multiple threads that run concurrently: a thread to acquire the photon peak amplitude and feed a circular buffer, threads to evaluate the electron density and temperatures, and a thread that supplies corresponding output voltages and feeds the output card.In summary, the new real-time TS system has been proven to meet the 60-Hz system requirement. For this reason, the software implementation was deemed successful. In future NSTX-U campaigns, this diagnostic will be a great asset enabling real-time plasma density and temperature control.
DA - 2019///
PY - 2019///
DO - 10.1080/15361055.2019.1658037
VL - 75
IS - 8
SP - 835-840
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073835505&partnerID=MN8TOARS
KW - Thomson scattering
KW - real time
KW - NSTX-U
KW - multiple threads
KW - object-oriented architecture
ER -
TY - JOUR
TI - A scalable real-time framework for Thomson scattering analysis: Application to NSTX-U
AU - Laggner, F. M.
AU - Diallo, A.
AU - LeBlanc, B. P.
AU - Rozenblat, R.
AU - Tchilinguirian, G.
AU - Kolemen, E.
T2 - Review of Scientific Instruments
AB - A detailed description of a prototype setup for real-time (RT) Thomson scattering (TS) analysis is presented and implemented in the multi-point Thomson scattering (MPTS) diagnostic system at the National Spherical Torus Experiment Upgrade (NSTX-U). The data acquisition hardware was upgraded with RT capable electronics (RT-analog digital converters and a RT server) that allow for fast digitization of the laser pulse signal of eight radial MPTS channels. In addition, a new TS spectrum analysis software for a rapid calculation of electron temperature (Te) and electron density (ne) was developed. Testing of the RT hardware and data analysis software was successfully completed and benchmarked against the standard, post-shot evaluation. Timing tests were performed showing that the end-to-end processing time was reproducibly below 17 ms for the duration of at least 5 s, meeting a 60 Hz deadline by the laser pulse repetition rate over the length of a NSTX-U discharge. The presented RT framework is designed to be scalable in system size, i.e., incorporation of additional radial channels by solely adding additional RT capable hardware. Furthermore, it is scalable in its operation duration and was continuously running for up to 30 min, making it an attractive solution for machines with long discharges such as advanced, non-inductive tokamaks or stellarators.
DA - 2019/4//
PY - 2019/4//
DO - 10.1063/1.5088248
VL - 90
IS - 4
SP - 043501
UR - http://dx.doi.org/10.1063/1.5088248
ER -
TY - JOUR
TI - Overview of physics studies on ASDEX Upgrade
T2 - Nuclear Fusion
AB - Abstract The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation ( q 95 = 5.5, ) at low density. Higher installed electron cyclotron resonance heating power 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m −1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and E r allow for inter ELM transport analysis confirming that E r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of ‘natural’ no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle—measured for the first time—or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.
DA - 2019///
PY - 2019///
DO - 10.1088/1741-4326/ab18b8
VL - 59
IS - 11
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85072124840&partnerID=MN8TOARS
KW - nuclear fusion
KW - magnetic confinement
KW - tokamak physics
KW - ITER
KW - DEMO
ER -
TY - JOUR
TI - Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade
T2 - Nuclear Fusion
AB - Within the EUROfusion MST1 work package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a double null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.
DA - 2019///
PY - 2019///
DO - 10.1088/1741-4326/ab2211
VL - 59
IS - 8
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85070909412&partnerID=MN8TOARS
KW - H-mode
KW - type-II ELMs
KW - grassy ELMs
KW - plasma triangularity
KW - separatrix density
KW - ballooning modes
ER -
TY - JOUR
TI - Divertor currents during type-I edge-localized modes on the DIII-D tokamak
AU - Knolker, M.
AU - Evans, T.E.
AU - Wingen, A.
AU - Bortolon, A.
AU - Laggner, F.M.
AU - Moyer, R.A.
AU - Nazikian, R.
AU - Zohm, H.
T2 - Nuclear Fusion
AB - Measurements of divertor currents on DIII-D lead to new insights in nonlinear edge-localized mode (ELM) dynamics and a possible mechanism to explain their explosive growth. Rapidly oscillating currents flowing into the divertor before a significant increase in divertor heat flux occurs are measured with an array of shunted tiles and characterized. Extrapolation results in total n = 0 currents of 5–10 kA flowing into a concentric circle near the strike point. The detected Fourier harmonics appear consistent with a mix of low-n modes (n < 4) with currents up to 4 kA. A heuristic framework for ELM currents is developed based on thermoelectric origin of the tile currents with flow through regions inside of the nominal separatrix and found consistent with the current measurements. A current flow through the confined plasma leading to increased stochasticity and transport at the plasma edge could provide a mechanism for additional nonlinear growth as sought for in computational ELM simulations. Results also imply that ELM currents may open the possibility to manipulate the ELM character by perturbations through non-axisymmetric divertor bias or tile insulation.
DA - 2019///
PY - 2019///
DO - 10.1088/1741-4326/ab3e9a
VL - 59
IS - 12
SP - 126020
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076731355&partnerID=MN8TOARS
KW - ELM
KW - divertor
KW - current
KW - nonlinear
ER -
TY - JOUR
TI - Active conditioning of asdex upgrade tungsten plasma-facing components and discharge enhancement through boron and boron nitride particulate injection
AU - Lunsford, R.
AU - Rohde, V.
AU - Bortolon, A.
AU - Dux, R.
AU - Herrmann, A.
AU - Kallenbach, A.
AU - McDermott, R.M.
AU - David, P.
AU - Drenik, A.
AU - Laggner, F.
AU - Maingi, R.
AU - Mansfield, D.K.
AU - Nagy, A.
AU - Neu, R.
AU - Wolfrum, E.
T2 - Nuclear Fusion
AB - The injection of boron (B) and boron nitride (BN) powders into ASDEX Upgrade H-mode discharges have demonstrated effective control of tungsten influx in low density/collisionality operational regimes, similar to conventional boronization methods. Sub-mm powder particles are gravitationally accelerated into the upper edge of a lower single null H-mode plasma with a boundary shape roughly conforming to the shape of the poloidal midplane limiters. Visible spectroscopy measurements at one of the outer limiter showed increases in both B and N signal levels, as well as elevated B levels in the divertor, and an increase in total radiated power by greater than a factor of two during BN injection. Globally the BN injection improved energy confinement by 10%–20%, associated with improvements in pedestal performance similar to gaseous N injection. Following conditioning discharges with B powder injection, three low gas-fueling discharges with magnetic perturbations for ELM suppression were successfully conducted. These first results suggest that the application of B containing powders can be used to both improve plasma performance in real-time, and to improve overall wall conditions for subsequent discharges.
DA - 2019///
PY - 2019///
DO - 10.1088/1741-4326/ab4095
VL - 59
IS - 12
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076618975&partnerID=MN8TOARS
KW - boronization
KW - boron powder
KW - ASDEX-Upgrade
KW - boron nitride
ER -
TY - CONF
TI - Model-based resilience assessment framework for autonomous systems
AU - Diaconeasa, M.A.
AU - Mosleh, A.
AU - Morozov, A.
AU - Tai, A.T.
AB - Abstract While automation technologies advance faster than ever, gaps of resilience capabilities between autonomous and human-operated systems have not yet been identified and addressed appropriately. To date, there exists no generic framework for resilience assessment that is applicable to a broad spectrum of domains or able to take into account the impacts on mission-scenario-level resilience from system-specific attributes. In the proposed framework, resilience is meant to describe the ability of a system, in an open range of adverse scenarios, to maintain normal operating conditions or to recover from degraded or failed states in order to provide anticipated functions or services to achieve mission success. The term resilience is introduced in relation with classical terms such as fault, error, failure, fault-tolerance, reliability, and risk. The proposed model-based resilience assessment framework is based on a resilience ontology that enables the use of system models into reliability and risk models for transparent, persistent, and up-to-date modeling and quantification. A SysML profile and associated OWL ontology are defined to enable the use of a range of resilience mechanisms into the design and operation of a system.
C2 - 2019///
C3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
DA - 2019///
DO - 10.1115/IMECE2019-12288
VL - 13
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85078694886&partnerID=MN8TOARS
ER -
TY - CONF
TI - A numerical and experimental study supporting a methodology for live monitoring, leak detection, and automatic response in water pipelines
AU - Chalgham, W.
AU - Diaconeasa, M.
AU - Gottumukkala, R.
AU - Seibi, A.
AB - Abstract This paper describes a numerical analysis supported by small scale experiments for demonstrating a monitoring and leak detection methodology. This study can be used to build a full-scale water pipeline monitoring and response system. The monitoring system is able to monitor the pipeline health and respond to hazard conditions through the use of multiple sensors driven by a hybrid rule-based and statistical monitoring control strategy. The system is programmed to automatically shut off its pump in the event of out-of-bounds/out-of-statistical control conditions detected by its sensors. In addition, this paper presents a numerical simulation analysis approach supported by an experiment that aims at finding a relationship between the location and size of an induced leak and the reported sensor data. The obtained results are used to inform a probabilistic model that can be used to estimate the leak location and size based on flow rate variations. The proposed project will enhance remote pipeline monitoring and structural safety by offering real-time data and automatic emergency response capabilities.
C2 - 2019///
C3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
DA - 2019///
DO - 10.1115/IMECE2019-11861
VL - 13
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85078704982&partnerID=MN8TOARS
ER -
TY - CONF
TI - A dynamic pipeline network health assessment software platform for optimal risk-based prioritization of inspection, structural health monitoring, and proactive management
AU - Chalgham, W.
AU - Diaconeasa, M.
AU - Wu, K.-Y.
AU - Mosleh, A.
AB - Abstract The Pipeline Health Monitoring and Management web application is a risk-based pipeline integrity management support tool to support pipeline operators in decision-making and planning activities. The platform design is supported by a multi-disciplinary science and engineering approach for a comprehensive, state-of-the-art solution. The goal of the software platform is to integrate the data, methods, and technologies into a dynamic pipeline heath monitoring system supported by multiple probabilistic predictive models such as dynamic hybrid causal logic, corrosion prognosis, and sensor placement optimization models. This total system health management support tool provides online or offline updates on the reliability state of various segments of the pipeline system, and dynamically updates the recommendations on when and where to take mitigating actions, e.g., increase or decrease inspection frequency. The pipeline health monitoring system software platform under development provides the ability for (a) Integrity assessment based on comprehensive range of evidence from sensing, inspection, and real-time monitoring in addition to probabilistic integration of mechanistic models and data on failure mechanisms relating to various causal factors (e.g., uniform corrosion, pitting corrosion, etc.) for assessment of the pipe segment health (remaining life); (b) Dynamic pipeline network probabilistic health assessment model software for optimal risk-based prioritization of inspection and proactive management, and (c) Geographical mapping capabilities that will augment the interaction of the pipeline operators with the pipeline system such as viewing pipeline/sensor locations, and adding new pipelines if desired. The selected computational foundation for the assessment is the hybrid causal logic engine with a wide range of capabilities in terms of system model building and probabilistic analysis of various types of evidence for assessment of model parameters. On this foundation we are adding capabilities to integrate predictive corrosion models, sensor placement optimization, and computational modules to perform pipeline health assessment, and develop inspection and maintenance strategies. The resulting software will be deployed as a control room health dashboard and hand-held web-based field inspection support tool.
C2 - 2019///
C3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
DA - 2019///
DO - 10.1115/IMECE2019-11806
VL - 13
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85078700418&partnerID=MN8TOARS
ER -
TY - CONF
TI - A smart pipeline monitoring and emergency response system using web services
AU - Chalgham, W.
AU - Diaconeasa, M.
AU - Elgazzar, K.
AU - Seibi, A.
AB - Abstract The Smart Pipeline Monitoring System introduced in this paper demonstrates a proof-of-concept for replicating a full-scale water pipeline system that is able to monitor the pipeline health and respond to hazard conditions through the use of multiple sensors and a statistical monitoring control strategy. The system aims at mitigating the effects of common sources of damage that occur in pipelines, such as leaks and overheating, by offering real time data visualization and autonomous actions in case of emergencies. The data visualization is provided by a desktop user interface and a mobile application. In the case of a detected anomaly, described by out-of-bounds/out-of-statistical control conditions detected by the sensors, the system is programmed to shut off its pump and alert the supervisors by SMS instantly. The proposed monitoring system will enhance remote pipeline monitoring and structural safety by offering real-time data and automatic emergency response capabilities. Our experimental results and prototype implementation show that the proposed system effectively detects anomaly conditions under various realistic scenarios and takes necessary safety measures to prevent further damages.
C2 - 2019///
C3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
DA - 2019///
DO - 10.1115/IMECE2019-11825
VL - 13
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85078707186&partnerID=MN8TOARS
ER -
TY - RPRT
TI - Comparison of Higher-Order Neutron Scattering Cross Sections
DA - 2019///
PY - 2019///
DO - 10.2172/1593864
ER -
TY - RPRT
TI - An Analytic Benchmark for the Solution to the Isotopic Fission Spectrum Mixture Problem
AB - In neutron transport calculations, it is common to specify material compositions in terms of constituent isotopes. Material compositions may be described by isotope number densities and associated microscopic cross sections. For general reaction cross sections, the macroscopic cross sections of a composition are simply the summation of the sum of the products of isotope number densities and microscopic cross sections. A notable exception is the mixture of the neutron fission spectrum in fissile material. To demonstrate proper and improper mixture of the neutron fission spectrum, a zero-dimensional test problem is developed. Using the test problem, it is demonstrated that the improper mixing of the fission spectrum results in an eigenvalue error of approximately 65 pcm. Though this may seem small, any error in such a simple calculation is unacceptable. In similar infinite-homogeneous test problems, eigenvalue errors of more than 300 pcm have been observed. It is also shown that the error due to fission spectrum mixing can be exaggerated for computer program verification purposes. It is concluded that the proper mixture of the neutron fission spectrum is essential for accurate neutron transport simulations. The effect of improper neutron fission spectrum mixture is demonstrated and quantified and this test problem may be used for verification purposes in the future.
DA - 2019///
PY - 2019///
DO - 10.2172/1593873
ER -
TY - JOUR
TI - Simulation of Fast Reactors with the Finite Element Method and Multiphysics Models
AU - Dawn, William C.
T2 - North Carolina State University
DA - 2019/5//
PY - 2019/5//
UR - http://www.lib.ncsu.edu/resolver/1840.20/36547
ER -
TY - JOUR
TI - Retrospective uranium enrichment potential using solid state dosimetry techniques on ubiquitous building materials
AU - Hayes, R.B.
T2 - Journal of Nuclear Material Management
DA - 2019///
PY - 2019///
VL - 47
IS - 2
SP - 4–12
ER -
TY - CONF
TI - Demonstration of a data-driven approach for error estimation in two-phase flow simulation using coarse-mesh CFD
AU - Bao, H.
AU - Feng, J.
AU - Zhang, H.
AU - Dinh, N.
C2 - 2019///
C3 - Transactions of the American Nuclear Society
DA - 2019///
DO - 10.13182/31051
VL - 121
SP - 1865-1868
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85092125933&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Fracture Mechanics-Based Study of Stress Corrosion Cracking of SS304 Dry Storage Canister for Spent Nuclear Fuel
AU - Tjayadi, Leonardi
AU - Kumar, Nilesh
AU - Murty, Korukonda L.
T2 - TMS 2019 148TH ANNUAL MEETING & EXHIBITION SUPPLEMENTAL PROCEEDINGS
AB - Many independent spent fuel storage installations (ISFSI) are located along the coastal regions in the US and the dry storage canisters consisting of spent nuclear fuels are envisioned to undergo chloride-induced stress corrosionCorrosion cracking (SCCSCC ) in heat-affected zoneHeat-affected zone (HAZ) . In the present study, we have investigated SCCSCC behavior of sensitized SS304H under substitute ocean water at room temperature using wedge opening loading (WOL) specimens. The alloy was sensitized at 600 °C for 215 h followed by microstructural characterizationCharacterization . The crack growth during the test was monitored using direct current potential dropPotential drop technique. The crack growthCrack growth rate for the SS304H alloy was within the same order of magnitude as reported in literature for SS304 alloy under chloride environment.
DA - 2019///
PY - 2019///
DO - 10.1007/978-3-030-05861-6_106
SP - 1089-1097
SN - 2367-1696
KW - Crack growth
KW - Fatigue pre-cracking
KW - Fracture mechanics
KW - Potential drop
KW - SCC
KW - Stainless steel
ER -
TY - JOUR
TI - The life and the contribution of B. R. Sehgal, G. Yadigaroglu and G. Hewitt: Remembrance statements
AU - Aksan, N.
AU - Andreani, M.
AU - Bechta, S.
AU - Corradini, M.
AU - D’Auria, F.
AU - Dhir, V.
AU - Frid, W.
AU - Jones, J.
AU - Jong, K.
AU - Lillington, J.
AU - Matar, O.
AU - Dinh, N.
AU - Ninokata, H.
AU - Podowski, M.
AU - Revankar, S.
AU - Riznic, J.
AU - Todreas, N.
AU - Tuomisto, H.
AU - Uspuras, E.
AU - Walker, S.
AU - Zhang, J.
T2 - Nuclear Engineering and Design
AB - Solicited or voluntary statements have been collected by the Editor of the Special Issue (SI). Tributes to Sehgal, Yadigaroglu and Hewitt are reported in the alphabetical order of those who originated them. The concise tributes by N. Todreas related to all the three scientists constitute the paper PII-1 in this SI and are also reported hereafter. Romney Duffey and John Jones wrote dedicated tributes with scientific insights which constitute PII-7 and PII-8 in this SI. A number of others helped with biographies of Sehgal, Yadigaroglu and Hewitt and are acknowledged in paper PII-2.
DA - 2019///
PY - 2019///
DO - 10.1016/j.nucengdes.2019.110252
VL - 354
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85070500941&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Validation and Uncertainty Quantification for Wall Boiling Closure Relations in Multiphase-CFD Solver
AU - Liu, Y.
AU - Dinh, N.
T2 - Nuclear Science and Engineering
AB - Two-fluid model-based multiphase computational fluid dynamics (MCFD) has been considered one of the most promising tools to investigate a two-phase flow and boiling system for engineering purposes. The MCFD solver requires closure relations to make the conservation equations solvable. The wall boiling closure relations, for example, provide predictions on wall superheat and heat partitioning. The accuracy of these closure relations significantly influences the predictive capability of the solver. In this paper, a study of validation and uncertainty quantification (VUQ) for the wall boiling closure relations in the MCFD solver is performed. The work has three purposes: (1) to identify influential parameters to the quantities of interest (QoIs) of the boiling system through sensitivity analysis (SA), (2) to evaluate the parameter uncertainty through Bayesian inference with the support of multiple data sets, and (3) to quantitatively measure the agreement between solver predictions and data sets. The widely used Kurul-Podowski wall boiling closure relation is studied in this paper. Several statistical methods are used, including the Morris Screening method for global SA, Markov Chain Monte Carlo for inverse Bayesian inference, and confidence interval as the validation metric. The VUQ results indicate that the current empirical correlations-based wall boiling closure relations achieved satisfactory agreement on wall superheat predictions. However, the closure relations also demonstrate intrinsic inconsistency and fail to give consistently accurate predictions for all QoIs over the well-developed nucleate boiling regime.
DA - 2019///
PY - 2019///
DO - 10.1080/00295639.2018.1512790
VL - 193
IS - 1-2
SP - 81-99
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85053869379&partnerID=MN8TOARS
KW - Multiphase-CFD
KW - Bayesian inference
KW - uncertainty quantification
KW - global sensitivity analysis
KW - validation metric
ER -
TY - CONF
TI - An artificial intelligence-guided decision support system for the nuclear power plant management
AU - Hanna, B.
AU - Son, T.C.
AU - Dinh, N.
C2 - 2019///
C3 - 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
DA - 2019///
SP - 394-406
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073712176&partnerID=MN8TOARS
ER -
TY - CONF
TI - Uncertainty quantification and reduction for multiphase-CFD solvers: A data-driven Bayesian approach supported by high-resolution local measurements
AU - Liu, Y.
AU - Sun, X.
AU - Liu, Y.
AU - Dinh, N.
C2 - 2019///
C3 - 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
DA - 2019///
SP - 3582-3597
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073755203&partnerID=MN8TOARS
ER -
TY - CONF
TI - Reynolds-averaged turbulence modeling using deep learning with local flow features
AU - Chang, C.-W.
AU - Fang, J.
AU - Dinh, N.T.
C2 - 2019///
C3 - 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
DA - 2019///
SP - 1698-1711
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073713566&partnerID=MN8TOARS
ER -
TY - CONF
TI - Development of a data-driven turbulence model for 3D thermal stratification simulation during reactor transients
AU - Zhu, Y.
AU - Dinh, N.
AU - Hu, R.
AU - Kraus, A.
C2 - 2019///
C3 - 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
DA - 2019///
SP - 2223-2234
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073734574&partnerID=MN8TOARS
ER -
TY - CONF
TI - Assessment of smoothed particle hydrodynamics methods for simulating the external-flooding scenario
AU - Lin, L.
AU - Dinh, N.
AU - Prescott, S.
AU - Bao, H.
AU - Montanari, N.
AU - Sampath, R.
C2 - 2019///
C3 - 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
DA - 2019///
SP - 981-992
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073736251&partnerID=MN8TOARS
ER -
TY - CONF
TI - A data-driven approach to scale bridging in system thermal-hydraulic simulation
AU - Bao, H.
AU - Youngblood, R.
AU - Zhang, H.
AU - Dinh, N.
AU - Lin, L.
AU - Lane, J.
C2 - 2019///
C3 - 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
DA - 2019///
SP - 6069-6082
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073761938&partnerID=MN8TOARS
ER -
TY - JOUR
TI - DIII-D research towards establishing the scientific basis for future fusion reactors
AU - Petty, C. C.
AU - Abadie, L.
AU - Abrams, T. W.
AU - Ahn, J.
AU - Akiyama, T.
AU - Aleynikov, P.
AU - Allcock, J.
AU - Allen, E. O.
AU - Allen, S.
AU - Anderson, J. P.
AU - Austin, M. E.
AU - Bak, J.
AU - Barada, K. K.
AU - Barbour, N.
AU - Bardoczi, L.
AU - Barr, J.
AU - Barton, J. L.
AU - Bass, E. M.
AU - Baylor, L. R.
AU - Beckers, J.
AU - Belli, E. A.
AU - Ashourvan, A.
AU - Battaglia, D.
AU - Berkery, J. W.
AU - Bartelli, N.
AU - Bialek, J. M.
AU - Boedo, J. A.
AU - Boivin, R. L.
AU - Bonoli, P. T.
AU - Bortolon, A.
AU - Boyer, M. D.
AU - Brambila, R. E.
AU - Bray, B.
AU - Briesemeister, A. R.
AU - Brennan, D. P.
AU - Bringuier, S. A.
AU - Brookmate, M. W.
AU - Brower, D. L.
AU - Brown, B. R.
AU - Brown, W. D.
AU - Buchenauer, D.
AU - Burke, M. G.
AU - Burrell, K. H.
AU - Butt, J.
AU - Buttery, R. J.
AU - Bykov, I
AU - Candy, J. M.
AU - Canik, J. M.
AU - Cao, N. M.
AU - Gomez, L. Carbajal
AU - Carlson, L. C.
AU - Carlstrom, T. N.
AU - Carter, T. A.
AU - Cary, W.
AU - Casali, L.
AU - Cengher, M.
AU - Chan, V. S.
AU - Chen, B.
AU - Chen, J.
AU - Chen, M.
AU - Chen, R.
AU - Chen, , Xi
AU - Choi, W.
AU - Chrobak, C.
AU - Chrystal, C.
AU - Churchill, R. M.
AU - Cianciosa, M.
AU - Clauser, C. F.
AU - Clement, M.
AU - Coburn, J.
AU - Collins, C. S.
AU - Cooper, A. W.
AU - Covele, B. M.
AU - Crippen, J. W.
AU - Crocker, N. A.
AU - Crowley, B. J.
AU - Dal Molin, A.
AU - Davis, E. M.
AU - deGrassie, J. S.
AU - del-Castillo-Negrete, C. A.
AU - Delgado-Aparicio, L. F.
AU - Diallo, A.
AU - Diem, S. J.
AU - Ding, R.
AU - Ding, S.
AU - Ding, W.
AU - Doane, J. L.
AU - Donovan, D. C.
AU - Drake, J.
AU - Du, D.
AU - Du, H.
AU - Du, X.
AU - Duarte, V
AU - Duran, J. D.
AU - Eidietis, N. W.
AU - Elder, D.
AU - Eldon, D.
AU - Ely, T. E.
AU - Eng, K. M.
AU - Engelhorn, K.
AU - Ennis, D.
AU - Erickson, K.
AU - Elwasif, W.
AU - Ernst, D. R.
AU - Evans, T. E.
AU - Fenstermacher, M. E.
AU - Ferraro, N. M.
AU - Ferron, J. R.
AU - Finkenthal, D. F.
AU - Fisher, P. A.
AU - Fishler, B.
AU - Fooks, J. A.
AU - Frassinetti, L.
AU - Frerichs, H. G.
AU - Fu, Y.
AU - Fulop, T.
AU - Gao, Q.
AU - Garcia, F.
AU - Garofalo, A. M.
AU - Giacomelli, L.
AU - Giraldez, E. M.
AU - Giroud, C.
AU - Flanagan, S. M.
AU - Gattuso, A.
AU - Glass, F.
AU - Gohil, P.
AU - Gong, X.
AU - Gorelov, Y. A.
AU - Granetz, R. S.
AU - Green, D. L.
AU - Greenfield, C. M.
AU - Grierson, B. A.
AU - Groebner, R. J.
AU - Grosnickle, W. H.
AU - Groth, M.
AU - Grunloh, H. J.
AU - Guo, H. Y.
AU - Guo, W.
AU - Guterl, J.
AU - Hager, R. C.
AU - Hahn, S.
AU - Halpern, F. D.
AU - Han, H.
AU - Hansink, M. J.
AU - Hanson, J. M.
AU - Harris, J.
AU - Haskey, S. R.
AU - Hatch, D. R.
AU - Heidbrink, W. W.
AU - Herfindal, J.
AU - Hill, D. N.
AU - Hill, M. D.
AU - Hinson, E. T.
AU - Holcomb, C. T.
AU - Holland, C. G.
AU - Holland, L. D.
AU - Hohmann, E. M.
AU - Holm, A. M.
AU - Hong, R.
AU - Hoppe, M.
AU - Houshmandyar, S.
AU - Howard, J.
AU - Howard, N. T.
AU - Hu, Q.
AU - Hu, W.
AU - Huang, H.
AU - Huang, J.
AU - Huang, Y.
AU - Hughes, G. A.
AU - Hughes, J.
AU - Humphreys, D. A.
AU - Hyatt, A. W.
AU - Ida, K.
AU - Igochine, V
AU - In, Y.
AU - Inoue, S.
AU - Isayama, A.
AU - Isler, R. C.
AU - Izzo, V. A.
AU - Jackson, M. R.
AU - Jarvinen, A. E.
AU - Jeon, Y.
AU - Ji, H.
AU - Jian, X.
AU - Jimenez, R.
AU - Johnson, C. A.
AU - Joseph, I
AU - Kaczala, D. N.
AU - Kaplan, D. H.
AU - Kates-Harbeck, J.
AU - Kellman, A. G.
AU - Kellman, D. H.
AU - Kessel, C. E.
AU - Khumthong, K.
AU - Kim, C. C.
AU - Kim, H.
AU - Kim, J.
AU - Kim, K.
AU - Kim, S. H.
AU - Kimura, W.
AU - King, J. R.
AU - Kirk, A.
AU - Kleijwegt, K.
AU - Knolker, M.
AU - Kohn, A.
AU - Kolemen, E.
AU - Kostuk, M.
AU - Kramer, G. J.
AU - Kress, P.
AU - Kriete, D. M.
AU - La Haye, R. J.
AU - Laggner, F. M.
AU - Lan, H.
AU - Lanctot, M. J.
AU - Lantsov, R.
AU - Lao, L. L.
AU - Lasnier, C. J.
AU - Lau, C.
AU - Law, K.
AU - Lawrence, D.
AU - Le, J.
AU - Lee, R. L.
AU - Lehnen, M.
AU - Leon, R.
AU - Leonard, A. W.
AU - Lesher, M.
AU - Leuer, J. A.
AU - Li, G.
AU - Li, K.
AU - Liao, K. T.
AU - Lin, Z.
AU - Liu, C.
AU - Liu, F.
AU - Liu, Y.
AU - Liu, Z.
AU - Loch, S.
AU - Logan, N. C.
AU - Lohr, J. M.
AU - Lore, J.
AU - Luce, T. C.
AU - Luhmann, N. C.
AU - Lunsford, R.
AU - Luo, C.
AU - Luo, Z.
AU - Lupin-Jimenez, L.
AU - Lvovskiy, A.
AU - Lyons, B. C.
AU - Ma, X.
AU - Maingi, R.
AU - Makowski, M. A.
AU - Mantica, P.
AU - Manuel, M.
AU - Margo, M. W.
AU - Marinoni, A.
AU - Marmar, E.
AU - Martin, W. C.
AU - Masline, R. L.
AU - Matsunage, G. K.
AU - Mauzey, D. M.
AU - Mauzey, P. S.
AU - MccLenaghan, J. T.
AU - McKee, G. R.
AU - McLean, A. G.
AU - McLean, H. S.
AU - Meier, E.
AU - Meitner, S. J.
AU - Menard, J. E.
AU - Meneghini, O.
AU - Merlo, G.
AU - Meyer, W. H.
AU - Miller, D. C.
AU - Miller, W. J.
AU - Moeller, C. P.
AU - Montes, K. J.
AU - Morales, M. A.
AU - Mordijck, S.
AU - Moser, A.
AU - Moyer, R. A.
AU - Muller, S. A.
AU - Munaretto, S.
AU - Murakami, M.
AU - Murphy, C. J.
AU - Muscatello, C. M.
AU - Myers, C. E.
AU - Nagy, A.
AU - Navratil, G. A.
AU - Nazikian, R. M.
AU - Neff, A. L.
AU - Neiser, T. F.
AU - Nelson, A.
AU - Nguyen, P.
AU - Nguyen, R.
AU - Nichols, J. H.
AU - Nocente, M.
AU - Nygren, R. E.
AU - O'Neill, R. C.
AU - Odstrcil, T.
AU - Ohdachi, S.
AU - Okabayashi, M.
AU - Olofsson, E.
AU - Ono, M.
AU - Orlov, D. M.
AU - Osborne, T. H.
AU - Pablant, N. A.
AU - Pace, D. C.
AU - Paguio, R. R.
AU - Martinez, A. Pajares
AU - Pan, C.
AU - Pankin, A.
AU - Park, J. M.
AU - Park, J.
AU - Park, Y.
AU - Parker, C. T.
AU - Parker, S. E.
AU - Parks, P. B.
AU - Pawley, C. J.
AU - Paz-Soldan, C. A.
AU - Peebles, W. A.
AU - Penaflor, B. G.
AU - Petrie, T. W.
AU - Peysson, Y.
AU - Pigarov, A. Y.
AU - Piglowski, D. A.
AU - Pinsker, R.
AU - Piovesan, P.
AU - Piper, N.
AU - Pitts, R. A.
AU - Pizzo, J. D.
AU - Podesta, M. L.
AU - Poli, F. M.
AU - Ponce, D.
AU - Porkolab, M.
AU - Porter, G. D.
AU - Prater, R.
AU - Qian, J.
AU - Ra, O.
AU - Rafiq, T.
AU - Raman, R.
AU - Rand, C.
AU - Randall, G. C.
AU - Rauch, J. M.
AU - Rea, C.
AU - Reinke, M. L.
AU - Ren, J.
AU - Ren, Q.
AU - Ren, Y.
AU - Rhodes, T. L.
AU - Rice, J.
AU - Rognlien, T. D.
AU - Rost, J. C.
AU - Rowan, W. L.
AU - Rudakov, D. L.
AU - Salmi, A.
AU - Sammuli, B. S.
AU - Samuell, C. M.
AU - Sandorfi, A. M.
AU - Sang, C.
AU - Sauter, O. J.
AU - Schissel, D. P.
AU - Schmitz, L.
AU - Schmitz, O.
AU - Schuster, E. J.
AU - Scoville, J. T.
AU - Seltzman, A.
AU - Sfiligoi, I
AU - Shafer, M.
AU - Shen, H.
AU - Shi, T.
AU - Shiraki, D.
AU - Si, H.
AU - Smith, D. R.
AU - Smith, S. P.
AU - Snipes, J. A.
AU - Snyder, P. B.
AU - Solano, E. R.
AU - Solomon, W. M.
AU - Sontag, A. C.
AU - Soukhanovskii, V. A.
AU - Spong, D. A.
AU - Stacey, W. M.
AU - Staebler, G. M.
AU - Stagner, L.
AU - Stahl, B.
AU - Stangeby, P. C.
AU - Stoltzfus-Dueck, T. J.
AU - Stotler, D. P.
AU - Strait, E. J.
AU - Su, D.
AU - Sugiyama, L. E.
AU - Sulyman, A. A.
AU - Sun, Y.
AU - Sung, C.
AU - Suttrop, W. A.
AU - Suzuki, Y.
AU - Svyatkovskiy, A.
AU - Sweeney, R. M.
AU - Taimourzadeh, S.
AU - Takechi, M.
AU - Tala, T.
AU - Tan, H.
AU - Tang, S.
AU - Tang, X.
AU - Taussig, D.
AU - Taylor, G.
AU - Taylor, N. Z.
AU - Taylor, T. S.
AU - Teklu, A.
AU - Thomas, D. M.
AU - Thomas, M. B.
AU - Thome, K. E.
AU - Thorman, A. R.
AU - Tinguely, R. A.
AU - Tobias, B. J.
AU - Tooker, J. F.
AU - Torreblanca, H.
AU - De Sousa, A. Torrezan
AU - Trevisan, G. L.
AU - Truone, D.
AU - Turce, E.
AU - Turnbull, A. D.
AU - Unterberg, E. A.
AU - Vaezi, P.
AU - Vail, P. J.
AU - Van Zeeland, M. A.
AU - Enriquez, M. Velasco
AU - Venkatesh, M. C.
AU - Victor, B. S.
AU - Volpe, E.
AU - Wade, M. R.
AU - Walker, M. L.
AU - Wall, J. R.
AU - Wallace, G. M.
AU - Waltz, R. E.
AU - Wang, G.
AU - Wang, H.
AU - Wang, Y.
AU - Wang, Z.
AU - Wang, F.
AU - Ward, S. H.
AU - Watkins, J. G.
AU - Watkins, M.
AU - Wehner, W. P.
AU - Weiland, M.
AU - Weisberg, D. B.
AU - Welander, A. S.
AU - White, A. E.
AU - White, R. B.
AU - Whyte, D.
AU - Wijkamp, T. A.
AU - Wilcox, R.
AU - Wilks, T.
AU - Wilson, H. R.
AU - Wingen, A.
AU - Wolfe, E.
AU - Wu, M.
AU - Wu, W.
AU - Wukitch, J.
AU - Xia, T.
AU - Xiang, N.
AU - Xiao, B.
AU - Xie, R.
AU - Xu, G.
AU - Xu, H.
AU - Xu, X.
AU - Yan, Z.
AU - Yang, Q.
AU - Yang, X.
AU - Yoshida, M.
AU - Yu, G.
AU - Yu, J. H.
AU - Yu, M.
AU - Zamperini, S. A.
AU - Zeng, L.
AU - Zhao, B.
AU - Zhao, D.
AU - Zhao, H.
AU - Zhao, Y.
AU - Zhu, Y.
AU - Zywicki, B.
T2 - NUCLEAR FUSION
AB - Abstract DIII-D research is addressing critical challenges in preparation for ITER and the next generation of fusion devices through focusing on plasma physics fundamentals that underpin key fusion goals, understanding the interaction of disparate core and boundary plasma physics, and developing integrated scenarios for achieving high performance fusion regimes. Fundamental investigations into fusion energy science find that anomalous dissipation of runaway electrons (RE) that arise following a disruption is likely due to interactions with RE-driven kinetic instabilities, some of which have been directly observed, opening a new avenue for RE energy dissipation using naturally excited waves. Dimensionless parameter scaling of intrinsic rotation and gyrokinetic simulations give a predicted ITER rotation profile with significant turbulence stabilization. Coherence imaging spectroscopy confirms near sonic flow throughout the divertor towards the target, which may account for the convection-dominated parallel heat flux. Core-boundary integration studies show that the small angle slot divertor achieves detachment at lower density and extends plasma cooling across the divertor target plate, which is essential for controlling heat flux and erosion. The Super H-mode regime has been extended to high plasma current (2.0 MA) and density to achieve very high pedestal pressures (~30 kPa) and stored energy (3.2 MJ) with H 98y2 ≈ 1.6–2.4. In scenario work, the ITER baseline Q = 10 scenario with zero injected torque is found to have a fusion gain metric independent of current between q 95 = 2.8–3.7, and a lower limit of pedestal rotation for RMP ELM suppression has been found. In the wide pedestal QH-mode regime that exhibits improved performance and no ELMs, the start-up counter torque has been eliminated so that the entire discharge uses ≈0 injected torque and the operating space is more ITER-relevant. Finally, the high- (⩽3.8) hybrid scenario has been extended to the high-density levels necessary for radiating divertor operation, achieving ~40% divertor heat flux reduction using either argon or neon with P tot up to 15 MW.
DA - 2019/11//
PY - 2019/11//
DO - 10.1088/1741-4326/ab024a
VL - 59
IS - 11
SP -
SN - 1741-4326
UR - https://publons.com/wos-op/publon/21450552/
KW - fusion
KW - plasma
KW - tokamak
KW - energy
KW - DIII-D
ER -
TY - JOUR
TI - High-resolution wall temperature measurements with distributed fiber optic sensors
T2 - International Journal of Thermal Sciences
AB - Conventional methods of surface temperature measurement are often unreliable, and other methods may not be practical in closed, high-temperature spaces. In this study, surface temperature measurements of the cooling panel of a natural circulation facility were performed with fiber optic distributed temperature sensors (DTS). High resolution surface temperature profiles of the cooling panel were acquired under two steady experimental conditions, and compared with measurements performed with nearby thermocouples. The total measurement error of the DTS results presented has been estimated to be ±4.4 °C. The results presented herein show that these DTS can reasonably measure surface temperature when installed with the methods developed in this study. Through the analysis of the DTS data collected, the interesting behavior of the cooling panel was revealed, providing new insights on the system's behavior that may be beneficial to the design and optimization of such heat transfer devices. These sensors can also provide the measurement density necessary for validation efforts with highly-resolved prediction methods such as finite element analysis (FEA) or computational fluid dynamics (CFD).
DA - 2019/8/2/
PY - 2019/8/2/
DO - 10.1016/j.ijthermalsci.2019.106042
UR - http://dx.doi.org/10.1016/j.ijthermalsci.2019.106042
KW - Distributed temperature sensors
KW - Surface temperature measurement
KW - Natural convection
KW - Natural circulation
KW - Reactor cavity cooling system
ER -
TY - JOUR
TI - A new cryogenic apparatus to search for the neutron electric dipole moment
AU - Ahmed, M. W.
AU - Alarcon, R.
AU - Aleksandrova, A.
AU - Baessler, S.
AU - Barron-Palos, L.
AU - Bartoszek, L. M.
AU - Beck, D. H.
AU - Behzadipour, M.
AU - Berkutov, I
AU - Bessuille, J.
AU - Blatnik, M.
AU - Broering, M.
AU - Broussard, L. J.
AU - Busch, M.
AU - Carr, R.
AU - Cianciolo, V
AU - Clayton, S. M.
AU - Cooper, M. D.
AU - Crawford, C.
AU - Currie, S. A.
AU - Daurer, C.
AU - Dipert, R.
AU - Dow, K.
AU - Dutta, D.
AU - Efremenko, Y.
AU - Erickson, C. B.
AU - Filippone, B. W.
AU - Fomin, N.
AU - Gao, H.
AU - Golub, R.
AU - Gould, C. R.
AU - Greene, G.
AU - Haase, D. G.
AU - Hasell, D.
AU - Hawari, A.
AU - Hayden, M. E.
AU - Holley, A.
AU - Holt, R. J.
AU - Huffman, P. R.
AU - Ihloff, E.
AU - Imam, S. K.
AU - Ito, T. M.
AU - Karcz, M.
AU - Kelsey, J.
AU - Kendellen, D. P.
AU - Kim, Y. J.
AU - Korobkina, E.
AU - Korsch, W.
AU - Lamoreaux, S. K.
AU - Leggett, E.
AU - Leung, K. K. H.
AU - Lipman, A.
AU - Liu, C. Y.
AU - Long, J.
AU - MacDonald, S. W. T.
AU - Makela, M.
AU - Matlashov, A.
AU - Maxwell, J. D.
AU - Mendenhall, M.
AU - Meyer, H. O.
AU - Milner, R. G.
AU - Mueller, P. E.
AU - Nouri, N.
AU - O'Shaughnessy, C. M.
AU - Osthelder, C.
AU - Peng, J. C.
AU - Penttila, S.
AU - Phan, N. S.
AU - Plaster, B.
AU - Ramsey, J. C.
AU - Rao, T. M.
AU - Redwine, R. P.
AU - Reid, A.
AU - Saftah, A.
AU - Seidel, G. M.
AU - Silvera, I
AU - Slutsky, S.
AU - Smith, E.
AU - Snow, W. M.
AU - Sondheim, W.
AU - Sosothikul, S.
AU - Stanislaus, T. D. S.
AU - Sun, X.
AU - Swank, C. M.
AU - Tang, Z.
AU - Dinani, R. Tavakoli
AU - Tsentalovich, E.
AU - Vidal, C.
AU - Wei, W.
AU - White, C. R.
AU - Williamson, S. E.
AU - Yang, L.
AU - Yao, W.
AU - Young, A. R.
T2 - JOURNAL OF INSTRUMENTATION
AB - A cryogenic apparatus is described that enables a new experiment, nEDM@SNS, with a major improvement in sensitivity compared to the existing limit in the search for a neutron Electric Dipole Moment (EDM). This apparatus uses superfluid 4He to produce a high density of Ultra-Cold Neutrons (UCN) which are contained in a suitably coated pair of measurement cells. The experiment, to be operated at the Spallation Neutron Source at Oak Ridge National Laboratory, uses polarized 3He from an Atomic Beam Source injected into the superfluid 4He and transported to the measurement cells where it serves as a co-magnetometer. The superfluid 4He is also used as an insulating medium allowing significantly higher electric fields, compared to previous experiments, to be maintained across the measurement cells. These features provide an ultimate statistical uncertainty for the EDM of 2−3× 10−28 e-cm, with anticipated systematic uncertainties below this level.
DA - 2019/11//
PY - 2019/11//
DO - 10.1088/1748-0221/14/11/P11017
VL - 14
SP -
SN - 1748-0221
KW - Noble liquid detectors (scintillation, ionization, double-phase)
KW - Cryogenic detectors
KW - Large detector systems for particle and astroparticle physics
KW - Neutron detectors (cold, thermal, fast neutrons)
ER -
TY - JOUR
TI - Application and Evaluation of Surrogate Models for Radiation Source Search
AU - Cook, Jared A.
AU - Smith, Ralph C.
AU - Hite, Jason M.
AU - Stefanescu, Razvan
AU - Mattingly, John
T2 - ALGORITHMS
AB - Surrogate models are increasingly required for applications in which first-principles simulation models are prohibitively expensive to employ for uncertainty analysis, design, or control. They can also be used to approximate models whose discontinuous derivatives preclude the use of gradient-based optimization or data assimilation algorithms. We consider the problem of inferring the 2D location and intensity of a radiation source in an urban environment using a ray-tracing model based on Boltzmann transport theory. Whereas the code implementing this model is relatively efficient, extension to 3D Monte Carlo transport simulations precludes subsequent Bayesian inference to infer source locations, which typically requires thousands to millions of simulations. Additionally, the resulting likelihood exhibits discontinuous derivatives due to the presence of buildings. To address these issues, we discuss the construction of surrogate models for optimization, Bayesian inference, and uncertainty propagation. Specifically, we consider surrogate models based on Legendre polynomials, multivariate adaptive regression splines, radial basis functions, Gaussian processes, and neural networks. We detail strategies for computing training points and discuss the merits and deficits of each method.
DA - 2019/12//
PY - 2019/12//
DO - 10.3390/a12120269
VL - 12
IS - 12
SP -
SN - 1999-4893
KW - surrogate modeling
KW - bayesian inference
KW - radiation source localization
ER -
TY - JOUR
TI - Influence of annealing parameters on the mechanical properties of heterogeneous lamella structured 5083 aluminum alloy
AU - Fang, X. T.
AU - He, G. Z.
AU - Ruiz, M.
AU - Zheng, C.
AU - Wang, Y. F.
AU - Li, Z. K.
AU - Zhu, Y. T.
T2 - LETTERS ON MATERIALS
AB - It has long been a research goal to obtain both high strength and ductility in structural materials. As the most important structural materials, metals and alloys are either strong or ductile, but seldom maintain both characteristics at the same time. After decades of attempts, extraordinary high strength has been achieved by involving nano- or ultrafine-grained structure. However, the ductility of these materials is relatively low. In the recent years, heterostructured materials have been demonstrated to possess superior combinations of strength and ductility, which are attributed to the hetero-deformation induced (HDI) strengthening and work hardening. The HDI hardening in previous studies is mainly caused by soft / hard domain boundaries. Here we report a heterogeneous lamella structure (HLS) in 5083 aluminum alloy fabricated by rolling and partial annealing. Superior combinations of strength and ductility have been achieved in the HLS Al-5083 through various annealing times and temperatures in this paper. Based on EBSD and TEM analysis, HDI hardening is an important reason for the excellent combination of strength and ductility. And soft / domain boundary hardening, and precipitation hardening are revealed as two important components of HDI hardening in Al-5083. These findings elucidate the HDI hardening mechanism in Al-5083 alloy, which will help us design the heterostructure of Al-5083 for engineering applications.
DA - 2019/12//
PY - 2019/12//
DO - 10.22226/2410-3535-2019-4-556-560
VL - 9
IS - 4
SP - 556-560
SN - 2410-3535
KW - heterostrctured
KW - hetero-deformation
KW - geometrically necessary dislocation
ER -
TY - CONF
TI - Opportunities for a graded approach in air sample assay and triage
AU - Hayes, RB
AU - O’Mara, RP
AU - Abdelrahman, F
T2 - 41st ESARDA Annual Meeting
C2 - 2019///
C3 - 41st ESARDA Annual Meeting symposium on safeguards and nuclear material management
CY - Stressa, Italy
DA - 2019///
PY - 2019/5/14/
DO - 10.2760/159550
SN - 978-92-76-08679-6
ER -
TY - JOUR
TI - Performance of Capillary Plasma Source With Combustible Materials
AU - Almousa, Nouf M.
AU - Bourham, Mohamed
T2 - IEEE Transactions on Plasma Science
AB - Application of an energetic material (EM) in a liquid or gaseous form to electrothermal (ET) plasma discharge systems can provide an energetic plasma jet that has desirable parameters for launching applications. In this energetic ET concept, the EM is basically injected into the plasma source that is operated in an ablation-free regime. The discharge and EM combustion processes have been simulated using the ETFlowCom code, which is an in-house developed energetic ET plasma model. In this article, the ETFlowCom code is used to predict the energetic plasma jet parameters such as temperature, pressure, heat flux, and exit velocity. Different computational case studies have been conducted using a variety of EM mixtures. The simulation results show that the generated energetic plasma jet has the density on the order of 10271/m3, kinetic pressure on the order of hundreds of MPa, and an exit velocity that can reach up to 6 km/s. These parameters are found to be functions of the EM type and the mixing ratio as well. The jet parameters show strong potential for launching applicability.
DA - 2019/11//
PY - 2019/11//
DO - 10.1109/TPS.2019.2940429
VL - 47
IS - 11
SP - 4873-4878
J2 - IEEE Trans. Plasma Sci.
OP -
SN - 0093-3813 1939-9375
UR - http://dx.doi.org/10.1109/TPS.2019.2940429
DB - Crossref
KW - Electrothermal chemical (ETC) launcher
KW - energetic electrothermal (ET) plasma
KW - hypervelocity plasma jets
ER -
TY - JOUR
TI - Study on Chemical Modifications of Glutathione by Cold Atmospheric Pressure Plasma (Cap) Operated in Air in the Presence of Fe(II) and Fe(III) Complexes
AU - Śmiłowicz, Dariusz
AU - Kogelheide, Friederike
AU - Stapelmann, Katharina
AU - Awakowicz, Peter
AU - Metzler-Nolte, Nils
T2 - Scientific Reports
AB - Abstract Cold atmospheric pressure plasma is an attractive new research area in clinical trials to treat skin diseases. However, the principles of plasma modification of biomolecules in aqueous solutions remain elusive. It is intriguing how reactive oxygen and nitrogen species (RONS) produced by plasma interact on a molecular level in a biological environment. Previously, we identified the chemical effects of dielectric barrier discharges (DBD) on the glutathione (GSH) and glutathione disulphide (GSSG) molecules as the most important redox pair in organisms responsible for detoxification of intracellular reactive species. However, in the human body there are also present redox-active metals such as iron, which is the most abundant transition metal in healthy humans. In the present study, the time-dependent chemical modifications on GSH and GSSG in the presence of iron(II) and iron(III) complexes caused by a dielectric barrier discharge (DBD) under ambient conditions were investigated by IR spectroscopy, mass spectrometry and High Performance Liquid Chromatography (HPLC). HPLC chromatograms revealed one clean peak after treatment of both GSH and GSSH with the dielectric barrier discharge (DBD) plasma, which corresponded to glutathione sulfonic acid GSO 3 H. The ESI-MS measurements confirmed the presence of glutathione sulfonic acid. In our experiments, involving either iron(II) or iron(III) complexes, glutathione sulfonic acid GSO 3 H appeared as the main oxidation product. This is in sharp contrast to GSH/GSSG treatment with DBD plasma in the absence of metal ions, which gave a wild mixture of products. Also interesting, no nitrosylation of GSH/GSSG was oberved in the presence of iron complexes, which seems to indicate a preferential oxygen activation chemistry by this transition metal ion.
DA - 2019///
PY - 2019///
DO - 10.1038/s41598-019-53538-y
VL - 9
IS - 1
ER -
TY - JOUR
TI - Quantified Validation with Uncertainty Analysis for Turbulent Single-Phase Friction Models
AU - Porter, Nathan W.
AU - Mousseau, Vincent A.
AU - Avramova, Maria N.
T2 - NUCLEAR TECHNOLOGY
AB - This paper introduces a framework for model selection that includes parameter estimation, uncertainty propagation, and quantified validation. The framework is applied to single-phase turbulent friction modeling in CTF, which is a thermal-hydraulic code for nuclear engineering applications. The friction model is chosen because it is well understood and easy to separate from other physics, which allows focus to be on the model selection framework instead of on the particulars of the chosen model. Two different empirical models are compared: the McAdams Correlation and the Simplified McAdams Correlation. The parameter estimation is performed by calibrating each of the friction models to experimental data using the Delayed Rejection Adaptive Metropolis algorithm, which is a Markov Chain Monte Carlo method. State point uncertainties are also considered, which are determined based on measurement errors from the experiment. The input parameter distributions are propagated through CTF using a statistical method with 2000 samples. A variety of validation metrics is used to quantify which empirical model is more accurate. It is shown that model form uncertainty can be quantified using validation once all other sources of uncertainty—numerical, sampling, experimental, and parameter—have been quantitatively addressed. When multiple models are available, the one that has the smallest model form error can be selected. Though the framework is applied to a simple example here, the same process can quantify the model form uncertainty of more complicated physics, multiple models, and simulation tools in other fields. Therefore, this work is a demonstration of best practices for future assessments of model form uncertainty.
DA - 2019/12/2/
PY - 2019/12/2/
DO - 10.1080/00295450.2018.1548221
VL - 205
IS - 12
SP - 1607-1617
SN - 1943-7471
KW - Model form error
KW - uncertainty analysis
KW - validation
KW - friction factor
ER -
TY - JOUR
TI - Selected papers from the 2018 Best Estimate Plus Uncertainty International Conference (BEPU 2018) Foreword
AU - Petruzzi, Alessandro
AU - Ivanov, Kostadin
AU - Ivanov, Evgeny
T2 - NUCLEAR TECHNOLOGY
DA - 2019/12/2/
PY - 2019/12/2/
DO - 10.1080/00295450.2019.1676080
VL - 205
IS - 12
SP - III-IV
SN - 1943-7471
ER -
TY - JOUR
TI - Dynamics of strongly coupled two-component plasma via ultrafast spectroscopy
AU - Bataller, Alexander
AU - Latshaw, Alexandra
AU - Koulakis, John P.
AU - Putterman, Seth
T2 - Optics Letters
AB - A combination of ultrafast emission and transmission spectroscopy is presented that provides a model-independent temperature measurement and tracking of the expansion dynamics for a dense, strongly coupled plasma. For femtosecond laser breakdown of hydrogen gas at 10 bar, we observe a 30,000 K two-component plasma for hundreds of picoseconds where both electrons and protons have a strong coupling parameter value of $\Gamma \sim{0.5}$Γ∼0.5. Furthermore, the plasma's degree of ionization (45%) results in a condition where the Debye screening length (6 Å) is less than the interatomic spacing (13 Å). Plasma formation occurs under an isochoric initial condition, which simplifies hydrodynamic modeling of the plasma channel expansion. The channel radius is found to accelerate at a constant rate until the front is moving with the speed of sound. Comparing hydrogen and deuterium for the same breakdown conditions grants unique insight into the hydrodynamics of strongly coupled plasma due to their nearly identical electronic structure yet large mass difference. The ultimate goal of these experiments is to access a plasma regime where continuum mechanics become nonlocal, as compared with the hydrodynamic motion described by the Navier-Stokes equations.
DA - 2019/12/1/
PY - 2019/12/1/
DO - 10.1364/OL.44.005832
UR - https://doi.org/10.1364/OL.44.005832
ER -
TY - JOUR
TI - Effect of hydriding on the creep behavior of HANA-4 zirconium alloy
AU - Kombaiah, Boopathy
AU - Sarkar, Apu
AU - Murty, Korukonda Linga
T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
AB - HANA-4 (High Temperature Alloys for Nuclear Applications) is Zr-1.5 Nb alloy developed by the Korea Atomic Energy Research Institute for advanced nuclear fuel cladding applications. In this work, the effect of hydriding on the biaxial creep behavior of HANA-4 alloy was studied through internal pressurization of closed end tubes by applying a range of hoop stresses (27 MPa–156 MPa) at two temperatures: 400 °C and 500 °C. Test specimens included two HANA-4 tubes hydrided using an electrolytic method with 387 ppm and 715 ppm of hydrogen, respectively, and non-hydrided HANA-4 tubes as the control sample. To understand the effect of hydriding on creep, steady state creep rates and stress exponents of the specimens were determined from the creep data. Furthermore, in situ X-ray diffraction (XRD) experiments were conducted on the hydrided HANA-4 specimens during heating to detect the dissolution limit of the hydride phase. On examining the results of the creep tests and the XRD experiments collectively, it is concluded that hydrogen while being fully dissolved into the solid solution enhances the creep rate of HANA-4 tubes. On the other hand, hydrogen present, even partially, as hydride phase at the creep test temperature lowers the creep rate. The rate controlling mechanisms of creep in HANA-4, however, remained unchanged as noted from similar stress exponents of the hydrided and non-hydrided specimens. The rationale behind these observations is explained based up on models predicting the interaction of dislocations with hydrogen and hydride phase.
DA - 2019/11/8/
PY - 2019/11/8/
DO - 10.1016/j.msea.2019.138435
VL - 767
SP -
SN - 1873-4936
KW - Creep
KW - Zirconium
KW - Hydrogen
KW - X-Ray diffraction
KW - Mechanical Properties
KW - Process
ER -
TY - JOUR
TI - Low temperature cathodoluminescence study of Fe-doped beta-Ga2O3
AU - Hany, Ibrahim
AU - Yang, Ge
AU - Zhou, Chuanzhen Elaine
AU - Sun, Cheng
AU - Gundogdu, Kenan
AU - Seyitliyev, Dovletgeldi
AU - Danilov, Evgeny O.
AU - Castellano, Felix N.
AU - Sun, Dali
AU - Vetter, Eric
T2 - MATERIALS LETTERS
AB - Optical and electrical properties along the b-axis of Fe-doped β-Ga2O3 were studied using low temperature cathodoluminescence (CL) spectroscopy, optical absorption spectroscopy and current-voltage (IV) measurements. The optical absorption spectroscopy showed an absorption edge without near edge shoulder and the corresponding optical bandgap was calculated to be 4.45 eV using direct band gap treatment. The temperature dependent CL measurements exhibited a strong blue to ultraviolet (UV) band composed of multiple low intensity peaks in the blue range, a main blue peak, a main UV peak, and a weak UV band from the as-grown Fe-doped β-Ga2O3. After a controlled annealing in air, the emissions changed to a red to near infrared (R-NIR) band with two sharp peaks and an UV band that is resolved at room temperature to three UV broad peaks. The R-NIR sharp peaks from the air-annealed sample were ascribed to incorporation of nitrogen during air annealing.
DA - 2019/12/15/
PY - 2019/12/15/
DO - 10.1016/j.matlet.2019.126744
VL - 257
SP -
SN - 1873-4979
UR - https://doi.org/10.1016/j.matlet.2019.126744
ER -
TY - JOUR
TI - Gap conductance modeling II: Optimized model for UO2-Zircaloy interfaces
AU - Toptan, Aysenur
AU - Kropaczek, David J.
AU - Avramova, Maria N.
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - The model conventionally used to calculate heat transfer across the fuel-cladding gap in light water nuclear reactors is a modified version of the Ross-Stoute model. The model was modified to include gap distance in the formulation, which introduced additional uncertainties because the model parameters were not adjusted after the modification. In this study, this conventional model is optimized for uranium dioxide-Zircaloy interfaces using experimental data at high pressure for single- and multi-component gases. First, a calibration is performed for single-component gases. Second, the calibration is extended to multi-component gases, which allows for a demonstration of sources of uncertainty in the model. Third, a general form of the gap conductance model is optimized by combining both data sets. Difficulties arise due to: (i) inaccurate estimation of contact characteristics (e.g., number of solid contacts, deformation mechanism of surface irregularities, contact shapes) that are different for each experimental setup; (ii) the non-physical ratio of temperature jump distance to the gap distance for postulated model function form; (iii) an insufficient description of the appropriate heat transfer regime; and (iv) the pressure dependence of thermal conductivity for inert gases aside from helium. Lastly, a general model is optimized by setting the temperature jump distance at the wall to zero, which reduces possible uncertainties. This final analysis results in a more accurate prediction of the available experimental data. The Associated parameter uncertainty of the model is estimated by performing uncertainty propagation. Overall, the optimized model results in a larger gap conductance with significantly reduced error.
DA - 2019/12/15/
PY - 2019/12/15/
DO - 10.1016/j.nucengdes.2019.110289
VL - 355
SP -
SN - 1872-759X
KW - Gap conductance
KW - Continuum
KW - Ross-Stoute
KW - Nuclear fuel performance
KW - Uncertainty
KW - Doppler temperature
ER -
TY - RPRT
TI - Electromagnetics Simulations with Vector-valued Finite Elements in MOOSE
AU - Icenhour, C.T.
AU - Lindsay, A.D.
AU - Martineau, R.C.
AU - Shannon, S
DA - 2019///
PY - 2019///
M1 - INL/CON-18-52320-Rev000
SN - INL/CON-18-52320-Rev000
ER -
TY - JOUR
TI - Determination of NO densities in a surface dielectric barrier discharge using optical emission spectroscopy
AU - Offerhaus, B.
AU - Kogelheide, F.
AU - Jalat, D.
AU - Bibinov, N.
AU - Schulze, J.
AU - Stapelmann, K.
AU - Awakowicz, P.
T2 - Journal of Applied Physics
AB - A new computationally assisted diagnostic to measure NO densities in atmospheric-pressure microplasmas by Optical Emission Spectroscopy (OES) is developed and validated against absorption spectroscopy in a volume Dielectric Barrier Discharge (DBD). The OES method is then applied to a twin surface DBD operated in N2 to measure the NO density as a function of the O2 admixture (0.1%–1%). The underlying rate equation model reveals that NO(A2Σ+) is primarily excited by reactions of the ground state NO(X2Π) with metastables N2(A3Σu+).
DA - 2019/11/21/
PY - 2019/11/21/
DO - 10.1063/1.5094894
UR - https://doi.org/10.1063/1.5094894
ER -
TY - JOUR
TI - Initial TL/OSL/EPR Considerations for commercial diatomaceous earth in retrospective dosimetry and dating
AU - Hayes, Robert B
AU - O’Mara, Ryan P
AU - Hooper, David A
T2 - Radiation Protection Dosimetry
AB - Diatomaceous earth is found in various locations around the planet. It is caused by the deposited exoskeleton material formed by the death of large concentrated populations of diatoms. The exoskeleton is effectively pure silicate and as such becomes a prospective material for retrospective dosimetry and dating. This work investigated the thermoluminescence (TL) and optically stimulated luminescence properties of commercially obtained diatomaceous earth. The material was not found to have useful dosimetric properties with conventional TL methodologies but did provide large dose estimates using the Single Aliquot Regeneration technique on some subset samples. These findings for organic silicate did suggest some mechanisms explaining the sensitization process in geological silicate materials utilized in dosimetry and dating. Electron paramagnetic resonance was identified as a potential future method for evaluating this material as it revealed unique signal components not found in igneous or commercially produced silicates.
DA - 2019/2/26/
PY - 2019/2/26/
DO - 10.1093/rpd/ncz013
VL - 1-10
SN - 0144-8420 1742-3406
UR - http://dx.doi.org/10.1093/rpd/ncz013
ER -
TY - JOUR
TI - Misorientation characteristics and textural changes induced by dense twins in high-purity Ti sheet after small strain rolling
AU - Dai, JiaHong
AU - Zeng, LingGuo
AU - Li, ZhiJun
AU - Chai, LinJiang
AU - Zheng, ZhiYing
AU - Wu, Hao
AU - Murty, K. L.
AU - Guo, Ning
T2 - SCIENCE CHINA-TECHNOLOGICAL SCIENCES
DA - 2019/11//
PY - 2019/11//
DO - 10.1007/s11431-019-9555-9
VL - 62
IS - 11
SP - 1968-1975
SN - 1869-1900
KW - titanium sheet
KW - cold rolling
KW - misorientation
KW - twinning
KW - texture
ER -
TY - JOUR
TI - Nonvolatile Multilevel States in Multiferroic Tunnel Junctions
AU - Fang, Mei
AU - Zhang, Sangjian
AU - Zhang, Wenchao
AU - Jiang, Lu
AU - Vetter, Eric
AU - Lee, Ho Nyung
AU - Xu, Xiaoshan
AU - Sun, Dali
AU - Shen, Jian
T2 - PHYSICAL REVIEW APPLIED
AB - Electric field control of discrete states of resistance and spin using ferroelectricity is promising for next-generation multistate memory devices. In contrast to most ferroelectric devices, which employ merely two states, this article presents nonvolatile, multilevel resistance states in multiferroic tunnel junctions (MFTJs) with a PbZr${}_{0.2}$Ti${}_{0.8}$O${}_{3}$ tunneling barrier. The phenomenon is due to the ``mixed'' state of two ferroelectric domains, gradually interconverted by tunneling electroresistance and magnetoresistance in the external electric field. This work shows a fresh route to ferroelectric spintronic devices for potential neuromorphic computing applications.
DA - 2019/10/22/
PY - 2019/10/22/
DO - 10.1103/PhysRevApplied.12.044049
VL - 12
IS - 4
SP -
SN - 2331-7019
ER -
TY - JOUR
TI - Aqueous Corrosion Behavior of Cast CoCrFeMnNi Alloy
AU - Pathak, S.
AU - Kumar, N.
AU - Mishra, R. S.
AU - De, P. S.
T2 - JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
DA - 2019/10//
PY - 2019/10//
DO - 10.1007/s11665-019-04329-z
VL - 28
IS - 10
SP - 5970-5977
SN - 1544-1024
KW - alloy
KW - cyclic voltammetry
KW - passivity
KW - pitting corrosion
ER -
TY - JOUR
TI - Surface Erosion of Plasma-Facing Materials Using an Electrothermal Plasma Source and Ion Beam Micro-Trenches
AU - Coburn, J. D.
AU - Gebhart, T. E.
AU - Parish, C. M.
AU - Unterberg, E.
AU - Canik, J.
AU - Barsoum, M. W.
AU - Bourham, M.
T2 - Fusion Science and Technology
AB - Erosion characteristics of tungsten-alternative plasma-facing materials (PFMs) were tested under high heat flux conditions in the electrothermal plasma source facility at Oak Ridge National Laboratory. The PFMs of interest are high-purity β-3C chemical vapor deposition silicon carbide (SiC) and the MAX phases Ti3SiC2 and Ti2AlC [MAX = chemical formula Mn+1AXn, where M is an early transition metal (such as Ti or Ta), A is an A-group element (such as Si or Al), and X is carbon or nitrogen]. An erosion analysis method was developed using a combination of focused ion beam microscopy and scanning electron microscopy, carving micro-trench geometries into polished sample surfaces. Samples of SiC, Ti3SiC2, and Ti2AlC were exposed to the electrothermal plasma source alongside tungsten and monocrystalline silicon. Samples were exposed to a Lexan polycarbonate (C16H14O3) electrothermal plasma stream in a He environment, at a specified impact angle, with infrared camera diagnostics. Edge localized mode–relevant heat fluxes of 0.9 to 1 GW/m2 over 1-ms discharges were generated on the target surfaces. Tungsten samples exhibited pronounced melt-layer formation and deformation, with measured molten pits 2 to 10 μm in diameter and melt-layer depths of up to 7 μm deep. Surface erosion rates for Ti3SiC2 and Ti2AlC ranged from 80 to 775 μm/s and 85 to 470 μm/s, respectively. Both MAX phases exhibited extreme surface fracture and material ejection, with damage depths past 4 μm for Ti2AlC and 11 μm for Ti3SiC2. SiC displayed the best performance, in one case surviving 15 consecutive electrothermal plasma exposures with an average erosion rate of about 29 μm/s and no surface fracturing. SiC erosion rates ranged from 23 to 128 μm/s.
DA - 2019/6/19/
PY - 2019/6/19/
DO - 10.1080/15361055.2019.1623570
VL - 75
IS - 7
SP - 621-635
J2 - Fusion Science and Technology
LA - en
OP -
SN - 1536-1055 1943-7641
UR - http://dx.doi.org/10.1080/15361055.2019.1623570
DB - Crossref
KW - Plasma-facing material
KW - ion beam
KW - MAX phase ceramics
KW - silicon carbide
KW - erosion
ER -
TY - JOUR
TI - A Monte Carlo feasibility study for neutron based real-time range verification in proton therapy (vol 170, 09001, 2018)
AU - Ytre-Hauge, Kristian Smeland
AU - Skjerdal, Kyrre
AU - Mattingly, John
AU - Meric, Ilker
T2 - SCIENTIFIC REPORTS
AB - An amendment to this paper has been published and can be accessed via a link at the top of the paper.
DA - 2019/10/9/
PY - 2019/10/9/
DO - 10.1038/s41598-019-49488-0
VL - 9
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Gap conductance modeling I: Theoretical considerations for single- and multi-component gases in curvilinear coordinates
AU - Toptan, Aysenur
AU - Kropaczek, David J.
AU - Avramova, Maria N.
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - Abstract Accurate estimation of heat transfer across the gap is important in nuclear fuel performance because heat transfer across the fuel-to-cladding gap heavily impacts fuel temperatures and the thermo-mechanical performance of nuclear fuel rods. Better understood physics will allow a better prediction of the gap behavior. This paper focuses on providing an overview of the gap conductance model including theoretical considerations and underlying assumptions. The gap conductance is calculated considering three summed heat paths: fill gas conductance, direct thermal radiation, and solid contact conductance. Each heat transfer mechanism is described in detail. First, the models are generalized to curvilinear coordinates for diatomic/polyatomic molecules. Traditional models use one-dimensional Cartesian equations for a monatomic gas. Second, expressions for temperature jump distance and thermal accommodation coefficients are made consistent with the kinetic theory for both single- and multi-component gases. Lastly, fill gas thermal conductivity is updated to include its dependence on rod internal pressure.
DA - 2019/11//
PY - 2019/11//
DO - 10.1016/j.nucengdes.2019.110283
VL - 353
SP -
SN - 1872-759X
KW - Gap conductance
KW - Temperature jump distance
KW - Thermal accommodation coefficient
KW - Static load
KW - Mixture
ER -
TY - JOUR
TI - Room-Temperature Electron-Hole Liquid in Monolayer MoS2
AU - Yu, Yiling
AU - Bataller, Alexander W.
AU - Younts, Robert
AU - Yu, Yifei
AU - Li, Guoqing
AU - Puretzky, Alexander A.
AU - Geohegan, David B.
AU - Gundogdu, Kenan
AU - Cao, Linyou
T2 - ACS NANO
AB - Excitons in semiconductors are usually noninteracting and behave like an ideal gas, but may condense to a strongly correlated liquid-like state, i.e., electron–hole liquid (EHL), at high density and appropriate temperature. An EHL is a macroscopic quantum state with exotic properties and represents the ultimate attainable charge excitation density in steady states. It bears great promise for a variety of fields such as ultra-high-power photonics and quantum science and technology. However, the condensation of gas-like excitons to an EHL has often been restricted to cryogenic temperatures, which significantly limits the prospect of EHLs for use in practical applications. Herein we demonstrate the formation of an EHL at room temperature in monolayer MoS2 by taking advantage of the monolayer’s extraordinarily strong exciton binding energy. This work demonstrates the potential for the liquid-like state of charge excitations to be a useful platform for the studies of macroscopic quantum phenomena and the development of optoelectronic devices.
DA - 2019/9//
PY - 2019/9//
DO - 10.1021/acsnano.9b04124
VL - 13
IS - 9
SP - 10351-10358
SN - 1936-086X
KW - electron-hole plasma
KW - exciton
KW - phase transition
KW - molybdenum disulfide
KW - transitional metal dichalcogenides
KW - TMDC
ER -
TY - JOUR
TI - Exact diagonal representation of normal mode energy, occupation number, and heat current for phonon-dominated thermal transport
AU - Raj, Anant
AU - Eapen, Jacob
T2 - JOURNAL OF CHEMICAL PHYSICS
AB - Collective excitations of crystal vibrations or normal modes are customarily described using complex normal mode coordinates. While appropriate for calculating phonon dispersion, the mixed representation involving the complex conjugates does not allow the construction of equivalent phonon occupation number or modal dynamical quantities such as the energy or heat current specific to a wave-vector direction (q). Starting from a canonical solution that includes waves going to the left and right directions, we cast the Hamiltonian, normal mode population, and heat current in an exactly diagonalizable representation using real normal mode amplitudes. We show that the use of real amplitudes obviates the need for a complex modal heat current while making the passage to second quantization more apparent. Using nonequilibrium molecular dynamics simulations, we then compute the net modal energy, heat current, and equivalent phonon population in a linear lattice subjected to a thermal gradient. Our analysis paves a tractable path for probing and computing the direction-dependent thermal-phononic modal properties of dielectric lattices using atomistic simulations.
DA - 2019/9/14/
PY - 2019/9/14/
DO - 10.1063/1.5099936
VL - 151
IS - 10
SP -
SN - 1089-7690
ER -
TY - JOUR
TI - Quantification and propagation of neutronics uncertainties of the Kozloduy-6 VVER-1000 fuel assembly using SCALE 6.2.1 within the NEA/OECD benchmark for uncertainty analysis in modelling of LWRs
AU - Nyalunga, G. P.
AU - Naicker, V. V.
AU - Ivanov, K.
T2 - ANNALS OF NUCLEAR ENERGY
AB - This work is based on the benchmark for uncertainty analysis in modelling of light water reactors compiled by the Nuclear Energy Agency within the Organisation for Economic Cooperation and Development (OECD/NEA). The objective of the benchmark is to determine and verify uncertainty bounds for results of calculations of LWRs based on operating data using best-estimate codes. The main contribution of this paper is the quantification of uncertainties in the Kozloduy-6 VVER-1000 fuel assembly using SCALE-6.2.1 methodology. The benchmark consists of three phases, each with three exercises. Three reactor systems are also studied, viz. the PWR, VVER and BWR reactors. In this study, Phase I of the benchmark was considered for the uncertainty quantification. The sources of uncertainties are classified into three groups, namely uncertainties due to nuclear data, manufacturing tolerances and numerical uncertainties due to methods’ implementations. The calculations are carried out using KENO-VI to perform the neutronics calculations and TSUNAMI-2D/3D and SAMPLER to perform the sensitivity and uncertainty analysis. Nuclear data uncertainty has been identified to be the highest contributor of uncertainty of the VVER-1000 fuel assembly. Although this is true, the uncertainty due to other parameters must always be considered together with nuclear data, since some of them could be significant.
DA - 2019/11//
PY - 2019/11//
DO - 10.1016/j.anucene.2019.07.016
VL - 133
SP - 732-749
ER -
TY - JOUR
TI - Precision control of gamma-ray polarization using a crossed helical undulator free-electron laser
AU - Yan, Jun
AU - Mueller, Jonathan M.
AU - Ahmed, Mohammad W.
AU - Hao, Hao
AU - Huang, Senlin
AU - Li, Jingyi
AU - Litvinenko, Vladimir N.
AU - Liu, Peifan
AU - Mikhailov, Stepan F.
AU - Popov, Victor G.
AU - Sikora, Mark H.
AU - Vinokurov, Nikolay A.
AU - Wu, Ying K.
T2 - NATURE PHOTONICS
DA - 2019/9//
PY - 2019/9//
DO - 10.1038/s41566-019-0467-6
VL - 13
IS - 9
SP - 629-635
SN - 1749-4893
ER -
TY - JOUR
TI - Optimization of processor allocation for domain decomposed Monte Carlo calculations
AU - Ellis, J. Austin
AU - Evans, Thomas M.
AU - Hamilton, Steven P.
AU - Kelley, C. T.
AU - Pandya, Tara M.
T2 - PARALLEL COMPUTING
AB - Load imbalance plagues domain decomposed Monte Carlo calculations when sources are not uniform. Parallel efficiency for domain decomposed Monte Carlo transport calculations improves through a nonuniform allocation of processors over subdomains. We optimize the allocation with runtime diagnostics collected during a calibration step, then complete the full calculation. The diagnostic-based approach is compared to implicit filtering, an optimization algorithm for bound constrained noisy optimization problems. We consider both forward and hybrid radiation transport calculations to measure performance.
DA - 2019/9//
PY - 2019/9//
DO - 10.1016/j.parco.2019.06.001
VL - 87
SP - 77-86
SN - 1872-7336
KW - Monte Carlo transport
KW - Load imbalance
KW - Domain decomposition
KW - Noisy optimization
ER -
TY - JOUR
TI - Development of the multigroup cross section library for the CASL neutronics simulator MPACT: Verification
AU - Kim, Kang Seog
AU - Gentry, Cole A.
AU - Godfrey, Andrew T.
AU - Liu, Yuxuan
AU - Palmtag, Scott
T2 - ANNALS OF NUCLEAR ENERGY
AB - The MPACT neutronics module of the Consortium for Advanced Simulation of Light Water Reactors (CASL) core simulator is a 3D whole core transport code being developed for the CASL toolset, known as the Virtual Environment for Reactor Analysis (VERA). Key characteristics of the MPACT code include a subgroup method for resonance self-shielding and a whole-core transport solver with a 2D/1D synthesis method. Depletion capability is supported by coupling SCALE-ORIGEN with MPACT. A new ENDF/B-VII.1 MPACT 51-group library has been developed by using the AMPX/SCALE and CASL-XSTools code packages based on the procedure introduced in the companion paper, “Development of the Multigroup Cross Section Library for the CASL Neutronics Simulator MPACT: Method and Procedure.” The cross section library generation procedure, cross section library, and MPACT transport capability have been verified by performing various benchmark calculations and comparing the benchmark results to the continuous-energy (CE) Monte Carlo results. The code-to-code comparison for the benchmarks shows that the CASL neutronics simulator MPACT and its 51-group library are working reasonably.
DA - 2019/10//
PY - 2019/10//
DO - 10.1016/j.anucene.2019.03.041
VL - 132
SP - 1-23
SN - 0306-4549
UR - https://doi.org/10.1016/j.anucene.2019.03.041
KW - VERA
KW - MPACT
KW - Cross section library
KW - Benchmark
KW - Verification
ER -
TY - JOUR
TI - Validation and uncertainty quantification of multiphase-CFD solvers: A data-driven Bayesian framework supported by high-resolution experiments
AU - Liu, Yang
AU - Sun, Xiaodong
AU - Dinh, Nam T.
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - The two-fluid model-based Multiphase Computational Fluid Dynamics (MCFD) solvers are promising tools for a variety of engineering problems related to multiphase flows. Such a solver is a complex model system that consists of multiple closure relations with strong interactions. Furthermore, a typical engineering problem requires evaluation of multiple quantities of interest (QoIs) from the solver predictions. These features make the validation and uncertainty quantification (VUQ) of these MCFD solvers a challenging task. In this paper, we propose an approach for the VUQ of a two-fluid model-based MCFD solver based on a data-driven Bayesian framework. This framework relies on Bayesian inference to inversely quantify the parameter uncertainty and model form uncertainty and then propagate the obtained uncertainties through the solver to obtain the uncertainties of the QoI predictions. To make the Bayesian inference applicable to complicated MCFD simulations, two methods namely, parameter space reduction and surrogate modeling, are included in the proposed approach. Supported by high-resolution local measurements, this framework is able to simultaneously take multiple key QoIs into consideration. In the validation process, the area metric is extended to the Principal Component (PC) subspace so that the multiple correlated QoIs, in the form of spatial or temporal distributions, can be validated in a comprehensive manner. We demonstrate the applicability of the proposed approach with a case study of an adiabatic bubbly flow scenario.
DA - 2019/12/1/
PY - 2019/12/1/
DO - 10.1016/j.nucengdes.2019.110200
VL - 354
SP -
SN - 1872-759X
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85069632428&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Incremental Gains in Transuranic Activity Analysis in Air Samples for Radiological Emergency Response
AU - Cope, S. Joseph
AU - Hayes, Robert B.
T2 - Nuclear Technology
AB - The alpha activity discrimination problem between radon progeny and transuranic (TRU) isotopes is evaluated at the times relevant for radiological emergency response using temporal decay properties. This study evaluates various effects from naturally occurring radon progeny creating alpha spectral overlap with the TRU region of interest. The methodology helps to address the potential masking of a radiological threat at worst or, at best, inhibiting response efforts due to delays caused by high levels of radon progeny. This work seeks to provide a rapid, conservative TRU estimation method in as little as 30 min. Surrogate TRU activity is introduced to the assays via check sources as a validation test for discrimination against varied levels of radon progeny collected on environmental air samples. A 2-h activity decay profile counting window was sectioned into multiple combinations of 30-min increments to investigate optimal counting segments and to simulate potential field-collection scenarios with limited resource availability. The experiment sought to discriminate low levels of introduced TRU activity comparable to the natural background on each sampled filter. Using this approach, the study confirmed the utility of the estimation methodology in as little as 30 min. Additional measurement time taken in the decay profile demonstrated marked improvements in both accuracy and precision of the TRU activity estimate as expected. Studies on the potential functional dependence of fitting parameters that influence the TRU estimate and associated uncertainty may improve further model development. The methodology is flexible to accommodate any gross alpha/beta scalar counter and is designed to be implemented within a graded approach based on time and resource availability present in the response. The estimation framework enables rapid air assay with a proper technical basis in times not currently realized in radiological emergency response.
DA - 2019/4/15/
PY - 2019/4/15/
DO - 10.1080/00295450.2019.1590074
VL - 205
IS - 9
SP - 1219-1235
J2 - Nuclear Technology
LA - en
OP -
SN - 0029-5450 1943-7471
UR - http://dx.doi.org/10.1080/00295450.2019.1590074
DB - Crossref
KW - Air sampling
KW - emergency response
KW - transuranic activity
KW - radon progeny discrimination
ER -
TY - JOUR
TI - A framework for assessment of predictive capability maturity and its application in nuclear thermal hydraulics
AU - Athe, Paridhi
AU - Dinh, Nam
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - This work presents a formalized and computerized framework for the assessment of decision regarding the adequacy of a simulation tool for a nuclear reactor application. The decision regarding a code’s adequacy for an application is dependent on the assessment of different attributes that govern verification, validation, and uncertainty quantification of the code. In this work, the focus is on code validation. Therefore, the framework is developed and illustrated from the perspective of decision regarding the validation assessment of a code. Code validation assessment is performed based on the validation test results, data applicability, and process quality assurance factors. The process quality assurance factors warrant the trustworthiness of the evidence and help in checking people and process compliance with respect to the standard requirements. The proposed framework is developed using an argument modeling technique called Goal Structuring Notation (GSN). Goal structuring notation facilitates structural knowledge representation, information abstraction, evidence incorporation, and provides a skeletal structure for quantitative maturity assessment. The decision schema for the development of the decision model is based on the Predictive Capability Maturity Model (PCMM) and Analytic Hierarchy Process (AHP) and formalized using Goal structuring notation. Each decision attribute is formulated as a claim, where the degree of validity of the claim (attribute’s assessment) is expressed using different maturity levels. The GSN representation of the decision model is transformed into a confidence network to provide evidence-based quantitative maturity assessment using the Bayesian network. A metric based on the expected utility of maturity levels, called expected distance metric, is proposed to measure the distance between target maturity and achieved maturity on a scale of zero to one. Expected distance metric helps in comparing the assessment of different attributes and identification of major areas of concern in terms of modeling capability, data needs, and quality of assessment process. The practical application of the framework is demonstrated by a case study on validation assessment of a thermal-hydraulic code for a challenge problem called Departure from Nucleate Boiling (DNB).
DA - 2019/12/1/
PY - 2019/12/1/
DO - 10.1016/j.nucengdes.2019.110201
VL - 354
SP -
SN - 1872-759X
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85070311923&partnerID=MN8TOARS
KW - Maturity assessment
KW - Argumentation
KW - Bayesian network
KW - Thermal-hydraulics
KW - Decision analysis
KW - Goal structuring notation
ER -
TY - JOUR
TI - Optical and electrical properties of all-inorganic Cs2AgBiBr6 double perovskite single crystals
AU - Zhang, Zheng
AU - Yang, Ge
AU - Zhou, Chuanzhen
AU - Chung, Ching-Chang
AU - Hany, Ibrahim
T2 - RSC ADVANCES
AB - Temperature-dependent resistivity and cathodoluminescence (CL) measurements of solution-processed Cs2AgBiBr6 double perovskite single crystals.
DA - 2019/8/4/
PY - 2019/8/4/
DO - 10.1039/c9ra04045e
VL - 9
IS - 41
SP - 23459-23464
SN - 2046-2069
UR - https://doi.org/10.1039/C9RA04045E
ER -
TY - JOUR
TI - Effects of pulsed laser surface treatments on microstructural characteristics and hardness of CrCoNi medium-entropy alloy
AU - Chai, Linjiang
AU - Xiang, Kang
AU - Xia, Jiying
AU - Fallah, Vahid
AU - Murty, Korukonda L.
AU - Yao, Zhongwen
AU - Gan, Bin
T2 - PHILOSOPHICAL MAGAZINE
AB - A hot-swaged/annealed CrCoNi medium-entropy alloy (MEA) was surface-treated by pulsed laser at two different powers (400 and 200 W). Microstructural characteristics of the laser-modified zones were characterised and analysed by energy dispersive spectroscopy, electron backscatter diffraction and electron channelling contrast imaging techniques. Results show that melting and rapid solidification occur on the surfaces of both laser-treated specimens, and profuse annealing twins existing in the initial microstructures are essentially eliminated in the melting zone (MZ) with plentiful low-angle boundaries appearing. Meanwhile, the initial equiaxed grains are replaced by new grains in the MZ with either granular or columnar appearance (in the 2D cross-sectional views). These grains are comprised of fine cellular structures with relatively uniform sizes (∼1–2 μm in width/diameter), the formation of which is related to the segregation of Cr during solidification. With the laser power decreasing from 400 to 200 W, the volume of the MZ and grain sizes in its interior are reduced. This is due to less heat supply and faster cooling caused by reducing the laser power. Hardness tests reveal that the surfaces of both the laser-treated specimens are slightly softened (by 10–20%), and quantitative analyses suggest that this is mainly related to grain coarsening and the disappearance of annealing twins in the MZ.
DA - 2019/12/17/
PY - 2019/12/17/
DO - 10.1080/14786435.2019.1649499
VL - 99
IS - 24
SP - 3015-3031
SN - 1478-6443
KW - CrCoNi MEA
KW - laser surface treatment
KW - annealing twin
KW - hardness
KW - electron backscatter diffraction
ER -
TY - JOUR
TI - Dense Electron-Hole Plasma Formation and Ultra-Long Charge Lifetime in Monolayer MoS2 via Material Tuning
AU - Bataller, Alexander W
AU - Younts, Robert
AU - Rustagi, Avinash
AU - Yu, Yiling
AU - Ardekani, Hossein
AU - Kemper, Alexander
AU - Cao, Linyou
AU - Gundogdu, Kenan
T2 - Nano letters
DA - 2019///
PY - 2019///
ER -
TY - JOUR
TI - Sequential optimal positioning of mobile sensors using mutual information
AU - Schmidt, Kathleen
AU - Smith, Ralph C.
AU - Hite, Jason
AU - Mattingly, John
AU - Azmy, Yousry
AU - Rajan, Deepak
AU - Goldhahn, Ryan
T2 - STATISTICAL ANALYSIS AND DATA MINING
AB - Abstract Source localization, such as detecting a nuclear source in an urban area or ascertaining the origin of a chemical plume, is generally regarded as a well‐documented inverse problem; however, optimally placing sensors to collect data for such problems is a more challenging task. In particular, optimal sensor placement—that is, measurement locations resulting in the least uncertainty in the estimated source parameters—depends on the location of the source, which is typically unknown a priori . Mobile sensors are advantageous because they have the flexibility to adapt to any given source position. While most mobile sensor strategies designate a trajectory for sensor movement, we instead employ mutual information, based on Shannon entropy, to choose the next measurement location from a discrete set of design conditions.
DA - 2019/12//
PY - 2019/12//
DO - 10.1002/sam.11431
VL - 12
IS - 6
SP - 465-478
SN - 1932-1872
KW - Bayesian inference
KW - inverse problem
KW - mutual information
KW - sensor placement
KW - source localization
ER -
TY - JOUR
TI - Iteration Methods with Multigrid in Energy for Eigenvalue Neutron Diffusion Problems
AU - Cornejo, Luke R.
AU - Anistratov, Dmitriy Y.
AU - Smith, Kord
T2 - NUCLEAR SCIENCE AND ENGINEERING
AB - In this paper we present nonlinear multilevel methods with multiple grids in energy for solving the k-eigenvalue problem for multigroup neutron diffusion equations. We develop multigrid-in-energy algorithms based on a nonlinear projection operator and several advanced prolongation operators. The evaluation of the eigenvalue is performed in the space with smallest dimensionality by solving the effective one-group diffusion problem. We consider two-dimensional Cartesian geometry. The multilevel methods are formulated in discrete form for the second-order finite volume discretization of the diffusion equation. The homogenization in energy is based on a spatially consistent discretization of the group diffusion equations on coarse grids in energy. We present numerical results of model reactor-physics problems with 44 energy groups. They demonstrate performance and main properties of the proposed iterative methods with multigrid in energy.
DA - 2019///
PY - 2019///
DO - 10.1080/00295639.2019.1573601
VL - 193
IS - 8
SP - 803-827
SN - 1943-748X
KW - Neutron diffusion
KW - eigenvalue problems
KW - multigrid methods
KW - multilevel iteration methods
ER -
TY - JOUR
TI - Microstructure response of ferritic/martensitic steel HT9 after neutron irradiation: effect of dose
AU - Zheng, Ce
AU - Reese, Elaina R.
AU - Field, Kevin G.
AU - Marquis, Emmanuelle
AU - Maloy, Stuart A.
AU - Kaoumi, Djamel
T2 - JOURNAL OF NUCLEAR MATERIALS
AB - A ferritic/martensitic steel, HT9, was irradiated in the BOR-60 reactor to ∼17.1 and ∼35.1 displacements per atom (dpa) at 650 ± 23 K (377 ± 23 °C). Irradiated samples were comprehensively characterized using analytical scanning/transmission electron microscopy and atom probe tomography, with emphasis on the role of irradiation dose on the microstructure evolution. Radiation-induced Mn/Ni/Si-rich (G-phase) and radiation-enhanced Cr-rich (αʹ) precipitates were observed within the martensitic laths at all doses. In addition, the G-phase was also observed to precipitate heterogeneously at various defect sinks. The number density for these second-phase precipitates decreases while the size increases with increasing dose, resulting in an increase of the volume fraction. Both a <100> and a/2 <111> type loops were observed with the a <100> type being the predominant type at both doses. The proportion of a <100> loops is consistent with that previously observed in HT9 ion irradiated to similar doses at ∼693–743 K (∼420-470 °C). Only small cavities (diameter < 2 nm) were observed at ∼17.1 dpa whereas both small and large cavities were observed at ∼35.1 dpa, resulting in a bi-modal cavity size distribution at this dose. Alloying elements, Ni and Si, were observed to segregate to the cavity surface, forming Ni/Si-rich shells around the cavities. The swelling at ∼17.1 dpa is evaluated at ∼0.02% while the swelling at ∼35.1 dpa is found to be ∼0.07% with variations from grain to grain. attributed to the spatial variation of the density of large cavities (in different grains). The swelling data obtained in this study was compared with the neutron data of F/M steels available in the literature.
DA - 2019/9//
PY - 2019/9//
DO - 10.1016/j.jnucmat.2019.06.019
VL - 523
SP - 421-433
SN - 1873-4820
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85067602813&partnerID=MN8TOARS
KW - Ferritic/martensitic steels
KW - Neutron irradiation
KW - Microstructure
KW - Swelling
KW - Precipitation
KW - Segregation
ER -
TY - JOUR
TI - Insights into the plastic behavior of irradiated Ni-based alloy through in-situ TEM experiments: Formation and evolution of defect-free channels
AU - Kaoumi, D.
AU - Jammot, V
T2 - JOURNAL OF NUCLEAR MATERIALS
AB - Foils of Ni-based alloys are deformed in situ in a TEM at 298 K after irradiation at the same temperature to 1014 ions/cm2 with 1 MeV Kr ions. The irradiation effects on the dislocation sources, dislocation motion, and on dislocation interactions with each other and the microstructure are assessed through in-situ dynamic observations. Dislocation motion through the irradiated material is observed to be jerky and discontinuous, as they get pinned by the irradiation-induced defects and the progression of the pile-ups proceeds in bursts of multiple dislocations. Active sources of dislocations originating from the walls of the channels are captured in-situ. They provide dislocations that glide in the channel and progressively clear it of the defects. Dislocation interactions with irradiation defects result in their increase in length by absorption of the defects; dislocations can become longer than the width of the channel, which can lead to congested channels and heavily jogged dislocations, resulting in a higher driving force for dislocation cross-slip out of the channels into the outside matrix, a phenomenon also captured in-situ. Similar observations were done in both Inconel 617 and Haynes 230, a similar Ni-based alloy with different composition but similar Stacking Fault Energy, indicating that the mechanisms at play are not strongly dependent on the chemical composition.
DA - 2019/9//
PY - 2019/9//
DO - 10.1016/j.jnucmat.2019.05.037
VL - 523
SP - 33-42
SN - 1873-4820
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85066288070&partnerID=MN8TOARS
KW - In-situ TEM
KW - Dislocation dynamics
KW - Radiation damage
KW - Ni-based alloy
KW - Inconel 617
KW - Ion irradiation
KW - Plasticity
ER -
TY - JOUR
TI - Borate multicomponent of bismuth rich glasses for gamma radiation shielding application
AU - Sayyed, M.I.
AU - Kaky, Kawa M.
AU - Mhareb, M.H.A.
AU - Abdalsalam, Alyaa H.
AU - Almousa, Nouf
AU - Shkoukani, Ghada
AU - Bourham, Mohamed A.
T2 - Radiation Physics and Chemistry
AB - In this work, six borate-bismuth glasses have been synthesized using a conventional melt-quenching-aneling process with a composition of (80-x)B2O310ZnO10MgO-xBi2O3 where x = 10, 20, 30, 40, 50 and 60 mol%. The glasses were melted at 975 °C for 30 min and annealed at 300 °C for 5 h. Different physical properties of these glasses have been measured and estimated. X-ray diffraction has been utilized to investigate the structural nature of these glasses. Optical absorption and transmittance spectra have been measured for all samples in the range of 300–800 nm at room temperature. The cutoff wavelength of all glass samples was determined. In addition, the radiation shielding characterization for the glass samples was done by calculating the linear and mass attenuation coefficients, mean free path, and half value layer of the photon energy ranges between 0.015 and 15 MeV using MicroShield. It was found that the glass with the highest Bi2O3 content showed the best performance in attenuating gamma radiation by exhibiting the highest linear attenuation coefficient and both lowest mean free path and half value layer due to its high density of 7.107 g/cm3.
DA - 2019/8//
PY - 2019/8//
DO - 10.1016/j.radphyschem.2019.04.005
VL - 161
SP - 77-82
J2 - Radiation Physics and Chemistry
LA - en
OP -
SN - 0969-806X
UR - http://dx.doi.org/10.1016/j.radphyschem.2019.04.005
DB - Crossref
KW - Borate glasses
KW - Optical band gap
KW - MicroShield
KW - Attenuation
KW - Gamma photon
KW - Shielding
ER -
TY - JOUR
TI - Surrogate-Based Robust Design for a Non-Smooth Radiation Source Detection Problem
AU - Stefanescu, Razvan
AU - Hite, Jason
AU - Cook, Jared
AU - Smith, Ralph C.
AU - Mattingly, John
T2 - ALGORITHMS
AB - In this paper, we develop and numerically illustrate a robust sensor network design to optimally detect a radiation source in an urban environment. This problem exhibits several challenges: penalty functionals are non-smooth due to the presence of buildings, radiation transport models are often computationally expensive, sensor locations are not limited to a discrete number of points, and source intensity and location responses, based on a fixed number of sensors, are not unique. We consider a radiation source located in a prototypical 250 m × 180 m urban setting. To address the non-smooth properties of the model and computationally expensive simulation codes, we employ a verified surrogate model based on radial basis functions. Using this surrogate, we formulate and solve a robust design problem that is optimal in an average sense for detecting source location and intensity with minimized uncertainty.
DA - 2019/6//
PY - 2019/6//
DO - 10.3390/a12060113
VL - 12
IS - 6
SP -
SN - 1999-4893
KW - robust design in the average sense
KW - Particle Swarm
KW - radial basis functions
KW - radiation source detection
ER -
TY - JOUR
TI - A surrogate model based on sparse grid interpolation for boiling water reactor subchannel void distribution
AU - Bennett, Alexander
AU - Martin, Nicolas
AU - Avramova, Maria
T2 - ANNALS OF NUCLEAR ENERGY
AB - Boiling water reactors are simulated using nodal diffusion core simulators which rely upon homogenized and condensed cross sections from a lattice physics code. In the lattice calculation, the void distribution is typically assumed to be uniform in the radial direction. To remove this assumption, a thermal hydraulic code can be coupled with a lattice physics code to include a radial void distribution in the cross sections. To minimize the additional computational costs, a surrogate model can be generated for the thermal hydraulic code. In this research, a surrogate model is generated for the thermal hydraulic code F-COBRA-TF using sparse grid interpolation. The surrogate model is tested on how well it can reproduce the F-COBRA-TF void distribution for various conditions on the ATRIUM 10 assembly. The surrogate model is found to be effective at reproducing the F-COBRA-TF void distribution and reducing the computational costs from the order of minutes to about a second. A coupling is created between the surrogate model and the lattice physics code APOLLO2-A. Including the void distribution in the lattice physics calculation is found to have a large effect on the gadolinium worth.
DA - 2019/9//
PY - 2019/9//
DO - 10.1016/j.anucene.2019.03.022
VL - 131
SP - 51-62
SN - 0306-4549
KW - Sparse grids
KW - Void distribution
KW - Local void model
KW - F-COBRA-TF
KW - ATRIUM 10
KW - APOLLO2-A
ER -
TY - JOUR
TI - Application of the Monte Carlo Library Least-Squares (MCLLS) approach for chromium quantitative analysis in aqueous solution
AU - Zhang, Yan
AU - Tang, Bin
AU - Jia, WenBao
AU - Zhang, Xiongjie
AU - Wang, Renbo
AU - Li, Fusheng
AU - Gardner, Robin
T2 - APPLIED RADIATION AND ISOTOPES
AB - In the present work, a new in-situ prompt gamma-ray neutron activation analysis (PGNAA) setup was developed for the quantitative measurement of chromium (Cr) in aqueous solutions which consists of a 4" × 4″ inch Bismuth Germanate detector and a 300 mCi 241Americium-beryllium neutron source. A series of standard samples were prepared by dissolving Cr compounds in deionized water of analytical pure grade and measured using the in situ PGNAA setup. Quantitative spectrum analysis was conducted using Monte Carlo Library Least-Squares approach (MCLLS). Simulates of elemental library spectra were in silico modeled using the CEARCPG code, which was developed by Prof. Robin Gardner research group in North Carolina State University. The fitted spectra presented were in excellent agreement with the total experimental spectrum, and the correlation coefficients were all nearly 1. After applying the MCLLS approach, the minimum detectable concentration of Cr was 301.5 mg/L, better than that obtained with other setups, and the relative deviation of the Cr quantitative analysis accuracy was less than 4.09%.
DA - 2019/8//
PY - 2019/8//
DO - 10.1016/j.apradiso.2019.02.018
VL - 150
SP - 39-42
SN - 0969-8043
KW - PGNAA
KW - Chromium
KW - MCLLS
KW - Relative deviation
ER -
TY - JOUR
TI - The effects of increasing deformation strain on the microstructural evolution of a metastable beta-Zr alloy
AU - Liao, Zhongni
AU - Luan, Baifeng
AU - Zhang, Xinyu
AU - Liu, Riping
AU - Murty, Korukonda L.
AU - Liu, Qing
T2 - JOURNAL OF ALLOYS AND COMPOUNDS
AB - In this study, we investigated the morphology evolution of deformation-induced α', α″ martensite and retained β phase with increasing deformation strain in metastable β-Zr-43.2Ti-4.5Al-4.2V (wt. %) alloy by ex-situ and regular compression tests. Three types of deformation-induced α' martensite have been observed for the first time during deformation, namely, twinned α' martensite, untwinned α' martensite and paired α' martensite. Transitions in morphology of twinned α' martensite from thin plate to twinned plate and to widened twinned plate, eventually to {101¯2} twin-related domains and of untwinned α' martensite from thin plate to widened plate to domain have been observed with increasing deformation strains. The paired α' martensite is undergone a process in which the α' martensite impacted grain boundaries stimulating the nucleation of new α' martensite in neighboring grains, and then leading to martensite growth on both sides grow simultaneously. With progressive deformation, the nano-size deformation-induced α″ martensite changes from long thin plate to ladder-shaped plate to 90° rotation domains. The morphology evolution of untwinned α' martensite, paired α' martensite and α″ martensite are mainly related to the self-accommodation mechanism, while the morphology evolution of twinned α' martensite is mainly related to the plastic accommodation mechanism. The average hardness increased with increase in deformation strains, owing to the martensitic transformation strengthening along with dislocation multiplication strengthening.
DA - 2019/9/5/
PY - 2019/9/5/
DO - 10.1016/j.jallcom.2019.05.334
VL - 800
SP - 208-218
SN - 1873-4669
KW - Metastable beta-Zr alloy
KW - Plastic deformation
KW - Microstructure
KW - Martensite phase transformation
KW - Twinning
KW - Hardness
ER -
TY - JOUR
TI - Uncertainty quantification of two-phase flow and boiling heat transfer simulations through a data-driven modular Bayesian approach
AU - Liu, Yang
AU - Dinh, Nam T.
AU - Smith, Ralph C.
AU - Sun, Xiaodong
T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
AB - In this paper, we present an approach to inversely quantify the uncertainty of MCFD simulations through a data-driven modular Bayesian inference. Both the model parameter uncertainty and the model form uncertainty are evaluated in the proposed approach. Considering the high-dimensionality of parameter space related to the solver, we performed a sensitivity analysis to reduce the input parameter dimension for the Bayesian inference. Based on the reduced parameter dimension, surrogate models based on Gaussian Process (GP) and Principal Component Analysis (PCA) are constructed to reduce the computational cost in the Bayesian inference. Two case studies based on the proposed approach are performed, focusing on two-phase flow dynamics and on wall boiling heat transfer, respectively. In case study I, we are able to construct a GP-based surrogate model based on 8 principal components to represent the total 208 MCFD solver outputs. Moreover, both cases show that the proposed approach is able to quantify and reduce the parameter uncertainties with the support of experimental measurements. The posterior uncertainties of investigated parameters have 50%-90% narrowed uncertainty ranges compared to their prior uncertainties. Furthermore, a forward uncertainty propagation of the MCFD solver with the obtained uncertainties shows that the agreement between the solver predictions and experimental measurements are significantly improved.
DA - 2019/8//
PY - 2019/8//
DO - 10.1016/j.ijheatmasstransfer.2019.04.075
VL - 138
SP - 1096-1116
SN - 1879-2189
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85064892196&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Validation of a rapid, conservative transuranic alpha activity estimation method in air samples
AU - Cope, S Joseph
AU - Hayes, Robert B
T2 - Journal of Radiological Protection
AB - In air filter assay for radiological emergency response, radon (222Rn) and thoron (220Rn) progeny are known interferents to transuranic activity estimation. Previous work detailed a conservative, graded approach for TRU alpha activity estimation from air samples void of transuranic activity yet containing varying amounts of radon and thoron progeny. Validation of this method to produce rapid, conservative and defensible transuranic alpha activity estimates was accomplished through introduction of surrogate transuranic activity, 239Pu and 230Th check sources, along with the naturally occurring radioactive progeny from an environmental air filter. Following air collection, the filter was centre hole-punched with the transuranic check source placed underneath the filter during counting. With the surrogate transuranic activity introduced into the measurement, verification of the previously studied methodology for rapid transuranic activity estimation was determined with quantifiable conservative bias. 70 environmental filters with various levels of radon progeny and air sampling duration were collected; 35 examined with the 239Pu check source and 35 studied with the 230Th check source. To characterise the expected transuranic activity introduced to the counting experiment without the environmental interferents of radon and thoron progeny, 30 blank filters were counted using the described experimental setup with each of the respective surrogate sources. Following characterisation of the sources with blank filters, transuranic activity estimation comparison against the 70 environmental filters with natural background radioactive progeny interferents was accomplished. This work contributes to the comprehensive analysis of operational air samples by detailing validation results for a rapid and conservative transuranic alpha activity estimation methodology.
DA - 2019/6/25/
PY - 2019/6/25/
DO - 10.1088/1361-6498/ab1bfd
VL - 39
IS - 3
SP - 749-765
J2 - J. Radiol. Prot.
OP -
SN - 0952-4746 1361-6498
UR - http://dx.doi.org/10.1088/1361-6498/ab1bfd
DB - Crossref
KW - air monitoring
KW - radon progeny
KW - radiological emergency response
KW - alpha particles
ER -
TY - JOUR
TI - Demonstration of the relationship between sensitivity and identifiability for inverse uncertainty quantification
AU - Wu, Xu
AU - Shirvan, Koroush
AU - Kozlowski, Tomasz
T2 - Journal of Computational Physics
AB - Inverse Uncertainty Quantification (UQ), or Bayesian calibration, is the process to quantify the uncertainties of random input parameters based on experimental data. The introduction of model discrepancy term is significant because “over-fitting” can theoretically be avoided. But it also poses challenges in the practical applications. One of the mostly concerned and unresolved problem is the “lack of identifiability” issue. With the presence of model discrepancy, inverse UQ becomes “non-identifiable” in the sense that it is difficult to precisely distinguish between the parameter uncertainties and model discrepancy when estimating the calibration parameters. Previous research to alleviate the non-identifiability issue focused on using informative priors for the calibration parameters and the model discrepancy, which is usually not a viable solution because one rarely has such accurate and informative prior knowledge. In this work, we show that identifiability is largely related to the sensitivity of the calibration parameters with regards to the chosen responses. We adopted an improved modular Bayesian approach for inverse UQ that does not require priors for the model discrepancy term. The relationship between sensitivity and identifiability was demonstrated with a practical example in nuclear engineering. It was shown that, in order for a certain calibration parameter to be statistically identifiable, it should be significant to at least one of the responses whose data are used for inverse UQ. Good identifiability cannot be achieved for a certain calibration parameter if it is not significant to any of the responses. It is also demonstrated that “fake identifiability” is possible if model responses are not appropriately chosen, or if inaccurate but informative prior distributions are specified.
DA - 2019/11/1/
PY - 2019/11/1/
DO - 10.1016/j.jcp.2019.06.032
VL - 396
SP - 12-30
UR - http://dx.doi.org/10.1016/j.jcp.2019.06.032
KW - Inverse uncertainty quantification
KW - Modular Bayesian approach
KW - Identifiability
KW - Sensitivity
ER -
TY - JOUR
TI - Gaussian Process–Based Inverse Uncertainty Quantification for TRACE Physical Model Parameters Using Steady-State PSBT Benchmark
AU - Wang, C.
AU - Wu, X.
AU - Kozlowski, T.
T2 - Nuclear Science and Engineering
AB - In the framework of Best Estimate Plus Uncertainty methodology, the uncertainties involved in model predictions must be quantified to prove that the investigated design is reasonable and acceptable. The uncertainties in predictions are usually calculated by propagating input uncertainties through the simulation model, which requires knowledge of the model or code input uncertainties, for example, the means, variances, distribution types, etc. However, in best-estimate system thermal-hydraulic codes such as TRACE, some parameters in empirical correlations may have large uncertainties that are unknown to code users, and their uncertainties are therefore simply ignored or described by expert opinion.In this paper, the issue of missing uncertainty information for physical model parameters in the thermal-hydraulic code TRACE is addressed with inverse uncertainty quantification (IUQ), using the steady-state void fraction experimental data in the Organisation for Economic Co-operation and Development/Nuclear Energy Agency PSBT (Pressurized water reactor Sub-channel and Bundle Tests benchmark. The IUQ process is formulated through a Bayesian perspective, which can yield the posterior distributions of the uncertain inputs. A Gaussian process emulator is employed to significantly reduce the computational burden involved in sampling the posteriors using the Markov Chain Monte Carlo method. The posterior distributions are further used in forward uncertainty quantification and sensitivity analysis to quantify the influences of those parameters on the quantities of interest. The results demonstrate the effectiveness of the IUQ framework with a practical nuclear engineering example and show the necessity of quantifying and reducing uncertainty of physical model parameters in future work.
DA - 2019///
PY - 2019///
DO - 10.1080/00295639.2018.1499279
VL - 193
IS - 1-2
SP - 100-114
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85051918828&partnerID=MN8TOARS
KW - Inverse uncertainty quantification
KW - Gaussian process
KW - physical model parameter uncertainty
KW - PSBT benchmark
ER -
TY - JOUR
TI - Erosion characterization of SiC and Ti3SiC2 on DIII-D using focused ion beam micro-trenches
AU - Coburn, J.
AU - Unterberg, E.
AU - Barton, J.
AU - Rudakov, D.
AU - Bykov, I.
AU - Parish, C.M.
AU - Wilcox, R.
AU - Lasnier, C.
AU - Abrams, T.
AU - Watkins, J.
AU - Hillis, D.L.
AU - Bourham, M.
T2 - Nuclear Materials and Energy
AB - Abstract Plasma-facing materials in future large-scale fusion reactors must be designed to withstand high heat fluxes from extreme off-normal events such as edge localized modes and unmitigated plasma disruptions. The erosion rates of possible tungsten-alternative materials are tested under high heat flux conditions at the DIII-D National Fusion Facility. High-purity β-3C CVD silicon carbide was exposed alongside MAX phase ceramic Ti3SiC2 to both L- and H-mode plasma discharges in the DIII-D divertor. Samples survived average heat fluxes ranging from 2–10 MW/m2 over 16 s. A new micro-trench erosion measurement technique was successfully implemented and measured Ti3SiC2 and SiC erosion rates of 0–9 nm/s and 27–73 nm/s, respectively. Additionally, average ion impact angle estimates for an incident B-field angle of ∼1.5° from surface parallel were made using micro-trench impact patterns. Measurements ranged from θ = 24o–34o with respect to Bt and ϕ = 51.5o–55o below the surface normal.
DA - 2019/5//
PY - 2019/5//
DO - 10.1016/j.nme.2019.02.036
VL - 19
SP - 316-323
J2 - Nuclear Materials and Energy
LA - en
OP -
SN - 2352-1791
UR - http://dx.doi.org/10.1016/j.nme.2019.02.036
DB - Crossref
ER -
TY - JOUR
TI - Performance Evaluation of Surface-Activated Solid-State Welding for ASTM A992 Structural Steel
AU - Morrison, Machel L.
AU - Gould, Jerry
AU - Charit, Indrajit
AU - Hassan, Tasnim
T2 - JOURNAL OF MATERIALS IN CIVIL ENGINEERING
AB - This paper presents the results of a pilot study to evaluate a solid-state welding technology, called surface activated solid-state (SASS) welding, for joining structural steel members. SASS welding does not require bulk melting of base metals and can be readily automated to produce high quality joints free from volumetric flaws and without extensive operator training. In addition, this welding process is performed instantly over a plane, in contrast to sequentially along lines as in arc welding; consequently, the former achieves much higher production rates than the latter. Butt-welded joints constructed from A992 steel were SASS welded and subjected to a series of mechanical tests and metallurgical evaluations. Coupon test results indicate that the SASS-welded joints can overmatch the tensile strength and match the ductility of the base metal. However, in the as-welded condition, SASS-welded joints did not display sufficient notch toughness for use in demand critical applications. A metallurgical study of these joints suggests that coarse prior austenite grains, brittle secondary phases, and the texture of grain boundary ferrite at or near the joint interface were possible causes. Notch toughness of SASS welds was significantly improved by post-weld heat-treatment, particularly at temperatures higher than Ac3, which were observed to homogenize the microstructure across the weld joint, refine ferrite grains, and produce purely reconstructive phase transformation products (i.e., polygonal ferrite + pearlite). The improvement in notch toughness is believed to be a result of these microstructural changes.
DA - 2019///
PY - 2019///
DO - 10.1061/(ASCE)MT.1943-5533.0002805
VL - 31
IS - 8
ER -
TY - JOUR
TI - Calculation of threshold displacement energies in UO2
AU - Dacus, Benjamin
AU - Beeler, Benjamin
AU - Schwen, Daniel
T2 - JOURNAL OF NUCLEAR MATERIALS
AB - Despite the extensive utilization of uranium dioxide (UO2) as a fuel in commercial nuclear reactors, there is only minimal information regarding the fundamental nature of radiation damage at high temperatures, such as those experienced by the fuel under operation. In this work, molecular dynamics simulations have been performed to determine the threshold displacement energy (Ed) for oxygen and uranium in UO2 at 1500 K. Three definitions of displacement energy were employed to fully study the nature of low energy radiation damage: 1) the probability of having the primary knock-on atom (PKA) leave its original lattice site, 2) the probability that the PKA will permanently displace atoms from their original lattice site, and 3) the probability of forming a stable Frenkel pair. Additionally, four unique interatomic potentials were utilized to investigate uncertainties associated with potential choice in high temperature radiation damage studies in UO2. This work provides critical insight into the high temperature behavior of radiation damage in UO2, as well as the variation in behavior between oxygen and uranium PKAs.
DA - 2019/7//
PY - 2019/7//
DO - 10.1016/j.jnucmat.2019.04.002
VL - 520
SP - 152-164
SN - 1873-4820
ER -
TY - JOUR
TI - Exploiting fission chain reaction dynamics to image fissile materials
AU - Chapman, Pete
AU - Mueller, Jonathan
AU - Newby, Jason
AU - Mattingly, John
T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
AB - Abstract Radiation imaging is one potential method to verify nuclear weapons dismantlement. We present a method to discriminate between non-multiplying and multiplying neutron sources using a neutron coded aperture imaging system. This method applies time-correlated pulse-height (TCPH) analysis to identify neutrons in fission chain reactions and recreate images using only these events. This analysis was applied to measurements of weapons-grade plutonium (WGPu) metal and 252Cf performed at the Nevada National Security Site (NNSS) Device Assembly Facility in July 2015. The results demonstrate it is possible to eliminate the non-fissile 252Cf source from the image while preserving the fissile WGPu source. TCPH analysis was also applied to additional scenes in which the WGPu and 252Cf sources were measured individually. The results of these separate measurements further demonstrate the ability to remove the non-fissile 252Cf source and retain the fissile WGPu source. Simulations performed using MCNPX-PoliMi indicate that in a one hour measurement, hollow WGPu spheres are retained at a 1 σ level for neutron multiplications M ≃ 2 . 7 and above. This work has potential application to dismantlement verification where it may be valuable to verify that all neutron sources in an image are multiplying.
DA - 2019/8/11/
PY - 2019/8/11/
DO - 10.1016/j.nima.2019.05.001
VL - 935
SP - 198-206
SN - 1872-9576
KW - Disarmament verification
KW - Neutron coded aperture imaging
KW - Time-correlated pulse-height analysis
KW - Special nuclear material
ER -
TY - JOUR
TI - On the validity of the dilute gas assumption for gap conductance calculations in nuclear fuel performance codes
AU - Toptan, Aysenur
AU - Kropaczek, David J.
AU - Avramova, Maria N.
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - Abstract Fill gas thermal conductivity’s dependence on pressure is neglected in today’s nuclear fuel performance codes. Current codes assume that gas behaves as a dilute gas, but the pressure effect is more pronounced at temperatures lower than ten times the critical temperature of each pure gas. The validity of this assumption for nuclear fuel performance is examined herein. Theories related to dilute and dense gas properties are presented, along with their validation against literature data at up to 30 MPa for selected inert gases. Underlying assumptions are clearly described for each model, and their possible impacts on gap conductance calculations are discussed. The dilute gas assumption is valid for helium because it behaves as a dilute gas. However, the assumption is not valid in most gap conductance calculations when the gap is mostly occupied with either lower conductivity gaseous fission products or an initial fill gas other than helium.
DA - 2019/8/15/
PY - 2019/8/15/
DO - 10.1016/j.nucengdes.2019.04.042
VL - 350
SP - 1-8
SN - 1872-759X
KW - Fill gas thermal conductivity
KW - Gap conductance
KW - Fuel performance
KW - Doppler
KW - Mixture thermal conductivity
KW - Rod internal pressure
KW - Dilute
KW - Dense
ER -
TY - JOUR
TI - A multi-scale and multi-physics simulation methodology with the state-of-the-art tools for safety analysis in light water reactors applied to a turbine trip scenario (PART I)
AU - Hidalga, Patricio
AU - Abarca, Agustin
AU - Miro, Rafael
AU - Sekrhi, Abdelkrim
AU - Verdu, Gumersindo
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - The simulation of transient events is a requirement in the evaluation of the safety of Nuclear Power Plants. The Nuclear Authority request the operators to report the prediction of the evolution of the corresponding safety variables using simulation codes and methodologies that have proved to be validated against real data, whether experiments or plant measurements. Moreover, these simulation codes are used in the engineering work that a Nuclear Power Plant needs for planning a competitive and safe operation strategy. The available resources in simulation tools make possible complex analysis that can be used to predict realistic results. The consequence is the opportunity of making a safe and cost-efficient evaluation of the safety margins. Operators can use these tools for licensing to the Nuclear Authority and for calculation support of the operation of the reactor in whichever considered case. This paper presents a methodology that takes advantage of different simulation tools to join the capabilities in the Best Estimate (BE) simulation of transients for Light Water Reactors. This methodology works in different steps to account all the physics using the proper scale in a multi-physics and multi-scale approach. An automatic tool manages the data pre- and post-processing the corresponding input and output files. The purpose is to simulate the transient case in a coarse mesh and generate the boundary conditions for a simulation in more detailed scale with a finer mesh in the next step. Therefore, this methodology works generating the corresponding nodal cross section data to be used in coupled 3D thermal-hydraulics and neutron kinetics simulations run with system codes. A channel-by-channel core model is used in order to identify the critical fuel channel. Finally, the boundary conditions of the critical fuel channel are loaded in a pin-by-pin thermal-hydraulic model to perform the definitive Safety Analysis of the target variable, that is selected by the user. The methodology presented in this paper, is applied to a real fast transient case, a Turbine Trip event of fuel cycle 18 in Kernkraftwerk Leibstadt, KKL. The results of each step of this methodology have been validated against the available plant data and the selected target safety variable, the Critical Power Ratio at pin level, has been code-to-code verified. The results show good agreement proving the effectivity of this methodology.
DA - 2019/8/15/
PY - 2019/8/15/
DO - 10.1016/j.nucengdes.2019.05.008
VL - 350
SP - 195-204
SN - 1872-759X
KW - Simulation methodology
KW - LWR safety analysis
KW - Turbine trip
KW - Trace
KW - Parcs
KW - Cobra-tf
ER -
TY - JOUR
TI - Large-Scale Application of the Constraint Annealing Method for Pressurized Water Reactor Core Design Optimization
AU - Kropaczek, David J.
AU - Walden, Ryan
T2 - NUCLEAR SCIENCE AND ENGINEERING
AB - The constraint annealing method is presented and demonstrated for the solution of large-scale, multiconstrained problems in light water reactor fuel cycle optimization. Constraint annealing is a penalty-free method that eliminates the need for traditional constraint weighting factors by treating each objective function and constraint as separate and concurrently solved minimization problems within a global optimization search framework. The current application seeks to demonstrate the effectiveness of constraint annealing for a complex core loading pattern design problem containing multiple objective functions and constraints without the need for additional ad hoc control parameters. Two problems of varying degrees of complexity are analyzed. The first problem is defined by a single objective function based on maximizing cycle energy with two constraints based on power peaking and peak rod exposure. The second problem expands upon the first by adding an additional objective function for vessel fluence and four additional constraints based on controlled power peaking, steaming rate, moderator temperature coefficient, and alternate source term. Results demonstrate that constraint annealing inherently addresses issues of scaling associated with different objective function and constraint formulations as well as the impact on cycle energy.
DA - 2019///
PY - 2019///
DO - 10.1080/00295639.2018.1550970
VL - 193
IS - 5
SP - 523-536
SN - 1943-748X
KW - Pressurized water reactor
KW - core design
KW - optimization
ER -
TY - JOUR
TI - Constraint Annealing Method for Solution of Multiconstrained Nuclear Fuel Cycle Optimization Problems
AU - Kropaczek, David J.
AU - Walden, Ryan
T2 - NUCLEAR SCIENCE AND ENGINEERING
AB - A method is developed, assessed, and demonstrated for addressing objective functions and constraints within the context of combinatorial optimization problems. The penalty-free method developed, referred to as constraint annealing, eliminates the use of traditional constraint penalty factors by treating the objective functions and constraints as separate and concurrently solved minimization problems within a global optimization search framework. The basis of the constraint annealing algorithm is a highly scalable method based on the method of parallel simulated annealing with mixing of states. Unique to constraint annealing is a novel approach that employs both global solution acceptance and local objective function and constraint statistics in the calculation of adaptive cooling temperatures that are specific to each objective function and constraint. The constraint annealing method is assessed against a traditional penalty-factor approach for a realistic core loading pattern design problem and shown to be robust with respect to elimination of arbitrary weighting factors on constraint values. In addition, the constraint annealing method is demonstrated to be robust with respect to parallel scaling as well as improved optimization performance on high-performance-computing systems.
DA - 2019///
PY - 2019///
DO - 10.1080/00295639.2018.1554173
VL - 193
IS - 5
SP - 506-522
SN - 1943-748X
KW - Nuclear fuel management
KW - fuel cycle
KW - optimization
ER -
TY - JOUR
TI - A multi-scale and multi-physics simulation methodology with the state-of-the-art tools for safety analysis in Light Water Reactors applied to a Turbine Trip scenario (Part II)
AU - Hidalga, Patricio
AU - Abarca, Agustin
AU - Miro, Rafael
AU - Sekrhi, Abdelkrim
AU - Verdu, Gumersindo
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - The development of the computer technology, as well as the research in the different science fields governing the core behavior of a Light Water Reactor, allows implementing all the known physics and consider detailed scales of analysis. Conversely to conservative approaches, the Best Estimate approach applies the available science by means of models and correlations that are applied in different scales using simulation tools. With this approach, the critical elements of the core can be evaluated with realistic predictions that can adjust the operation conditions and core design to more cost-efficient values without compromising the safety of the Nuclear Power Plant. The authors of this paper present the second part of a multi-scale and multi-physics methodology for the evaluation of fast transients in Light Water Reactors. In this part, the results obtained from the coupled Neutron Kinetics and Thermal-Hydraulics channel-by-channel core model are used for a detailed thermal-hydraulic pin-by-pin analysis and thermomechanics pin model. The aim of this work is to evaluate the safety analysis of the critical fuel rod in Turbine Trip scenario. For that purpose, the critical fuel rod is located using the minimum Critical Power Ratio. This safety variable is predicted in a thermal-hydraulic pin-by-pin model using CTF-UPVIS code. Afterwards, the conditions of the critical rod are loaded in a pin model for a simulation with FRAPCON/FRAPTRAN. Moreover, this paper proves the Best Estimate capability of the presented methodology by means of comparing the results with equivalent simulations that are more conservative, or consist of more limited simulation scales. On the one hand, the Best Estimate prediction is compared against the envelope of the minimum Critical Power Ratio along the axial nodal distribution of the simulated fuel rod. In addition, another comparison is made against assuming constant fuel-cladding gas conductance, showing the enhancement added by considering the axial distribution of this parameter, provided by FRAPCON/FRAPTRAN. On the other hand, the results of this methodology are compared against the limitation of accounting only the bundle radial average value of the minimum Critical Power Ratio. Furthermore, the Best Estimate results are complemented with an Uncertainty and Sensitivity analysis that will define the statistical boundaries of the prediction according to the 95/95 criterion.
DA - 2019/8/15/
PY - 2019/8/15/
DO - 10.1016/j.nucengdes.2019.05.009
VL - 350
SP - 205-213
SN - 1872-759X
KW - Simulation methodology
KW - LWR safety analysis
KW - Turbine Trip
KW - CTF-UPVIS
KW - FRAPCON/FRAPTRAN
ER -
TY - JOUR
TI - Verification of Reduced Order Modeling based Uncertainty/Sensitivity Estimator (ROMUSE)
AU - Khuwaileh, Bassam
AU - Williams, Brian
AU - Turinsky, Paul
AU - Hartanto, Donny
T2 - NUCLEAR ENGINEERING AND TECHNOLOGY
AB - This paper presents a number of verification case studies for a recently developed sensitivity/uncertainty code package. The code package, ROMUSE (Reduced Order Modeling based Uncertainty/Sensitivity Estimator) is an effort to provide an analysis tool to be used in conjunction with reactor core simulators, in particular the Virtual Environment for Reactor Applications (VERA) core simulator. ROMUSE has been written in C++ and is currently capable of performing various types of parameter perturbations and associated sensitivity analysis, uncertainty quantification, surrogate model construction and subspace analysis. The current version 2.0 has the capability to interface with the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA) code, which gives ROMUSE access to the various algorithms implemented within DAKOTA, most importantly model calibration. The verification study is performed via two basic problems and two reactor physics models. The first problem is used to verify the ROMUSE single physics gradient-based range finding algorithm capability using an abstract quadratic model. The second problem is the Brusselator problem, which is a coupled problem representative of multi-physics problems. This problem is used to test the capability of constructing surrogates via ROMUSE-DAKOTA. Finally, light water reactor pin cell and sodium-cooled fast reactor fuel assembly problems are simulated via SCALE 6.1 to test ROMUSE capability for uncertainty quantification and sensitivity analysis purposes.
DA - 2019/7//
PY - 2019/7//
DO - 10.1016/j.net.2019.01.020
VL - 51
IS - 4
SP - 968-976
SN - 1738-5733
KW - Sensitivity/uncertainty estimation
KW - CASL
KW - VERA
KW - DAKOTA
KW - SCALE
KW - ROMUSE 2.0
ER -
TY - JOUR
TI - Doppler-free, Stark broadened profiles at low plasma densities in helium
AU - Zafar, Abdullah
AU - Martin, Elijah
AU - Shannon, Steve
T2 - Journal of Quantitative Spectroscopy and Radiative Transfer
AB - This work utilizes Doppler-free saturation spectroscopy to measure Doppler-free, Stark broadened spectral profiles for the π-polarization of the HeI 21P → 61D transition in a low density (ne=7×1010−2×1012 cm−3) helium plasma. The measurements were performed in an electron-cyclotron resonance discharge at 23 mTorr with electron density being diagnosed using a combination of Langmuir probe and microwave interferometry techniques. The Doppler-free profiles were observed to be nearly symmetric at ne < 1011 cm−3 but markedly asymmetric above this transition point. Electron density is extracted from the spectral data via fitting to a spectral model based on quasi-static Stark broadening. The fit results are compared to ne measurements obtained using a combination of Langmuir probe and microwave interferometry techniques. The fit and measured ne are shown to agree within 20% on average. Finally, the quasi-static model is shown to be valid in the low-density regime for 21P → 61D helium transition.
DA - 2019/6//
PY - 2019/6//
DO - 10.1016/j.jqsrt.2019.03.020
VL - 230
SP - 48-55
J2 - Journal of Quantitative Spectroscopy and Radiative Transfer
LA - en
OP -
SN - 0022-4073
UR - http://dx.doi.org/10.1016/j.jqsrt.2019.03.020
DB - Crossref
KW - Stark broadening
KW - Low-density
KW - Quasi-static
KW - Doppler-free
ER -
TY - JOUR
TI - Slug-to-churn vertical two-phase flow regime transition study using an interface tracking approach
AU - Zimmer, Matthew D.
AU - Bolotnov, Igor A.
T2 - INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
AB - Direct numerical simulation (DNS) coupled with an interface tracking method (ITM) is used to demonstrate the applicability of DNS to the study of vertical two-phase flow regime transition. The study focuses on the slug flow to churn-turbulent regime transition. PHASTA, a finite element based flow solver which utilizes the level set method for interface tracking, has been used to perform the presented simulations. A domain size study has been conducted in order to find pipe dimensions that match the natural wavelength of the periodic slug flow. A mesh resolution study has been completed. The results show that using DNS to simulate the slug-to-churn transition is within the capabilities of the code as the simulations agree well with experimental data and empirical knowledge. The simulations were analyzed to find flow features such as the velocity profile in the wake of a Taylor bubble and the bubble interface shape evolution during breakdown. An understanding of such features could help identify the driving physics behind the transition phenomenon.
DA - 2019/6//
PY - 2019/6//
DO - 10.1016/j.ijmultiphaseflow.2019.04.003
VL - 115
SP - 196-206
SN - 1879-3533
KW - Vertical two-phase flow regime transition
KW - Slug flow
KW - Churn-turbulent flow
KW - Direct numerical simulation
KW - Level set method
KW - Interface tracking method
ER -
TY - JOUR
TI - Deducing Phonon Scattering from Normal Mode Excitations
AU - Raj, Anant
AU - Eapen, Jacob
T2 - SCIENTIFIC REPORTS
AB - Abstract While the quantum scattering theory has provided the theoretical underpinning for phonon interactions, the correspondence between the phonon modes and normal modes of vibrations has never been fully established; for example, the nature of energy exchange during elementary normal mode interactions remains largely unknown. In this work, by adopting a set of real asymmetric normal mode amplitudes, we first discriminate the normal and Umklapp processes directly from atomistic dynamics. We then demonstrate that the undulating harmonic and anharmonic potentials, which allow a number of interaction pathways, generate several total-energy-conserving forward and backward scattering events including those which are traditionally considered as quantum-forbidden. Although the normal mode energy is proportional to the square of the eigen-frequency, we deduce that the energy exchanged from one mode to another in each elementary interaction is proportional to the frequency – a quantum-like restriction. We anticipate that the current approach can be utilized profitably to discover unbiased scattering channels, many traditionally quantum forbidden, with complex anharmonicities. Our discovery will aid in the development of next-generation Peierls-Boltzmann transport simulations that access normal mode scattering pathways from finite temperature ab initio simulations.
DA - 2019/5/30/
PY - 2019/5/30/
DO - 10.1038/s41598-019-43306-3
VL - 9
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Structural, optical, and shielding investigations of TeO2-GeO2-ZnO-Li2O-Bi2O3 glass system for radiation protection applications
AU - Sayyed, M. I.
AU - Mhareb, M. H. A.
AU - Abbas, Zinah Yaseen
AU - Almousa, Nouf
AU - Laariedh, Farah
AU - Kaky, Kawa M.
AU - Baki, S. O.
T2 - APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
DA - 2019/6//
PY - 2019/6//
DO - 10.1007/s00339-019-2709-3
VL - 125
IS - 6
SP -
SN - 1432-0630
ER -
TY - JOUR
TI - A data-driven framework for error estimation and mesh-model optimization in system-level thermal-hydraulic simulation
AU - Bao, Han
AU - Dinh, Nam T.
AU - Lane, Jeffrey W.
AU - Youngblood, Robert W.
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - Over the past decades, several computer codes have been developed for simulation and analysis of thermal-hydraulics and system response in nuclear reactors under operating, abnormal transient, and accident conditions. However, simulation errors and uncertainties still inevitably exist even while these codes have been extensively assessed and used. In this work, a data-driven framework (Optimal Mesh/Model Information System, OMIS) is formulated and demonstrated to estimate simulation error and suggest optimal selection of computational mesh size (i.e., nodalization) and constitutive correlations (e.g., wall functions and turbulence models) for low-fidelity, coarse-mesh thermal-hydraulic simulation, in order to achieve accuracy comparable to that of high-fidelity simulation. Using results from high-fidelity simulations and experimental data with many fast-running low-fidelity simulations, an error database is built and used to train a machine learning model that can determine the relationship between local simulation error and local physical features. This machine learning model is then used to generate insight and help correct low-fidelity simulations for similar physical conditions. The OMIS framework is designed as a modularized six-step procedure and accomplished with state-of-the-art methods and algorithms. A mixed-convection case study was performed to illustrate the entire framework.
DA - 2019/8/1/
PY - 2019/8/1/
DO - 10.1016/j.nucengdes.2019.04.023
VL - 349
SP - 27-45
SN - 1872-759X
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85064505536&partnerID=MN8TOARS
KW - Coarse mesh
KW - Error estimation
KW - System-level modeling and simulation
KW - Machine learning
KW - Physical feature
ER -
TY - JOUR
TI - CTF-R: A novel residual-based thermal hydraulic solver
AU - Porter, N. W.
AU - Mousseau, V. A.
AU - Avramova, M. N.
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - The traditional scientific process has been revolutionized by the advent of computational modeling, but the nuclear industry generally uses “legacy codes,” which were developed early in the evolution of computers. One example of a legacy code, the thermal hydraulic subchannel code CTF, is modernized in this work through the development of a novel residual-based version, CTF-R. Unlike its predecessor, CTF-R is not limited by the strict computational limitations of the early 1980’s, and can therefore be designed such that it is inherently flexible and easy to use. A case study is examined to demonstrate how the flexibility of the code can be used to improve simulation results. In this example, the coupling between the solid and liquid fields is examined. Traditionally, this coupling is modeled explicitly, which imposes numerical stability limits on the time step size. These limits are derived and it is shown that they are removed when the coupling is made implicit. Further, the development of CTF-R will enable future improvements in next generation reactor modeling, numerical methods, and coupling to other codes. Through the further development of CTF-R and other residual-based codes, state-of-the-art simulation is possible.
DA - 2019/7//
PY - 2019/7//
DO - 10.1016/j.nucengdes.2019.04.006
VL - 348
SP - 37-45
SN - 1872-759X
KW - Subchannel analysis
KW - Residual
KW - CTF
KW - COBRA
ER -
TY - JOUR
TI - Non-linear, time dependent target accuracy assessment algorithm for multi-physics, high dimensional nuclear reactor calculations
AU - Khuwaileh, Bassam A.
AU - Turinsky, Paul J.
T2 - PROGRESS IN NUCLEAR ENERGY
AB - Safety analysis and design optimization depend on the accurate prediction of various reactor core responses. Model predictions can be enhanced by reducing the uncertainty associated with the responses of interest. Accordingly, an inverse problem analysis can be designed to provide guidance to determine the optimum experimental program to reduce the uncertainties in model parameters, e.g. cross-sections and fuel pellet-clad thermal conductivity, so as to reduce the uncertainties in constrained reactor core responses. This process is referred to as target accuracy assessment. In this work a nonlinear algorithm to determine an optimum experimental program has been developed and tested. The algorithm is based on the construction of surrogate model to replace the original model used to predict the core responses and uncertainties, therefore, enabling the target accuracy assessment to treat non-linearity within reasonable computational cost. Subspace based projection techniques are used to identify the influential degrees of freedom, which are then used to construct the surrogate model. Once constructed, the new computationally efficient surrogate model is used to propagate uncertainties via Monte Carlo sampling. Moreover, this work replaces the classical objective function used for nuclear data target accuracy assessment with another that factors in the financial gains of the target accuracy assessment results and replaces [or can supplement] differential experiments with many times more readily available integral experiments. Finally, the proposed algorithm is applied on a 3-dimensional fuel assembly depletion problem with thermal-hydraulics feedback using the VERA-CS core simulator. Specifically, CASL Progression Problem Number 6 is the illustrative problem employed which resembles a pressurized water reactor fuel assembly.
DA - 2019/7//
PY - 2019/7//
DO - 10.1016/j.pnucene.2019.01.023
VL - 114
SP - 227-233
SN - 0149-1970
KW - Target accuracy assessment
KW - Uncertainty reduction
KW - Model calibration
KW - Surrogate modeling
ER -
TY - JOUR
TI - Evaluation of CdZnTeSe as a high-quality gamma-ray spectroscopic material with better compositional homogeneity and reduced defects
AU - Roy, Utpal N.
AU - Camarda, Giuseppe S.
AU - Cui, Yonggang
AU - Gul, Rubi
AU - Yang, Ge
AU - Zazvorka, Jakub
AU - Dedic, Vaclav
AU - Franc, Jan
AU - James, Ralph B.
T2 - SCIENTIFIC REPORTS
AB - Abstract X- and gamma-ray detectors have broad applications ranging from medical imaging to security, non-proliferation, high-energy physics and astrophysics. Detectors with high energy resolution, e.g. less than 1.5% resolution at 662 keV at room temperature, are critically important in most uses. The efficacy of adding selenium to the cadmium zinc telluride (CdZnTe) matrix for radiation detector applications has been studied. In this paper, the growth of a new quaternary compound Cd 0.9 Zn 0.1 Te 0.98 Se 0.02 by the Traveling Heater Method (THM) is reported. The crystals possess a very high compositional homogeneity with less extended defects, such as secondary phases and sub-grain boundary networks. Virtual Frisch-grid detectors fabricated from as-grown ingots revealed ~0.87–1.5% energy resolution for 662-keV gamma rays. The superior material quality with a very low density of defects and very high compositional homogeneity heightens the likelihood that Cd 0.9 Zn 0.1 Te 0.98 Se 0.02 will be the next generation room-temperature detector material.
DA - 2019/5/13/
PY - 2019/5/13/
DO - 10.1038/s41598-019-43778-3
VL - 9
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Time-Resolved Electron Density Measurement Characterization of E–H-Modes for Inductively Coupled Plasma Instabilities
AU - Coumou, David J.
AU - Smith, Shaun T.
AU - Peterson, David J.
AU - Shannon, Steven C.
T2 - IEEE Transactions on Plasma Science
AB - Inductively coupled plasma sources driven by RF power at low-pressure regimes are well adopted for high-volume manufacturing of semiconductor devices. One vexing challenge to the utility of these plasma processing reactors is the existence of the E-H-mode transition. Industry notably avoids the process region associated with this transition, where plasma instabilities and bimodal power coupling prohibit reliable RF power delivery. One plasma instability detailed in this paper is associated with a hysteresis in coupled RF power (current) varying for the E-mode, or weakly capacitive coupling to the plasma, in comparison to the stronger current coupling in the H-mode, where inductive coupling is preferentially dominant. As a result, approximately two orders of magnitude of electron density is relinquished in this transition region from serving industrial manufacturing processes. We characterize the plasma parameter variation through the E-mode to H-mode with a time-resolved measurement of the electron density. Electronegative chemistries are incorporated into our experimental setup. The experimental scheme serves to evaluate RF power delivery and ameliorate its coupling through the transition region. We seek to extend this paper to adopt more efficient power coupling for toroidal plasma sources.
DA - 2019/5//
PY - 2019/5//
DO - 10.1109/TPS.2019.2909476
VL - 47
IS - 5
SP - 2102-2109
J2 - IEEE Trans. Plasma Sci.
OP -
SN - 0093-3813 1939-9375
UR - http://dx.doi.org/10.1109/TPS.2019.2909476
DB - Crossref
KW - Electromagnetic propagation
KW - frequency response
KW - ionization
KW - meteorology
KW - microwave antennas
KW - microwave circuits
KW - microwave measurement
KW - plasma density
KW - plasma diagnostics
KW - plasma measurements
KW - plasma properties
KW - plasma sheaths
KW - plasma simulation
KW - plasma sources
KW - plasma stability
KW - plasma temperature
KW - plasmas
KW - radio frequency
KW - RF signals
KW - signal processing
ER -
TY - JOUR
TI - Classification of machine learning frameworks for data-driven thermal fluid models
AU - Chang, Chih-Wei
AU - Dinh, Nam T.
T2 - INTERNATIONAL JOURNAL OF THERMAL SCIENCES
AB - Thermal fluid processes are inherently multi-physics and multi-scale, involving mass-momentum-energy transport phenomena at multiple scales. Thermal fluid simulation (TFS) is based on solving conservative equations, for which – except for “first-principles” direct numerical simulation – closure relations (CRs) are required to provide microscopic interactions or so-called sub-grid-scale physics. In practice, TFS is realized through reduced-order modeling, and its CRs as low-fidelity models can be informed by observations and data from relevant and adequately evaluated experiments and high-fidelity simulations. This paper is focused on data-driven TFS models, specifically on their development using machine learning (ML). Five ML frameworks are introduced including physics-separated ML (PSML or Type I ML), physics-evaluated ML (PEML or Type II ML), physics-integrated ML (PIML or Type III ML), physics-recovered (PRML or Type IV ML), and physics-discovered ML (PDML or Type V ML). The frameworks vary in their performance for different applications depending on the level of knowledge of governing physics, source, type, amount and quality of available data for training. Notably, outlined for the first time in this paper, Type III models present stringent requirements on modeling, substantial computing resources for training, and high potential in extracting value from “big data” in thermal fluid research. The current paper demonstrates and investigates ML frameworks in three examples. First, we utilize the heat diffusion equation with a nonlinear conductivity model formulated by convolutional neural networks (CNNs) and feedforward neural networks (FNNs) to illustrate the applications of Type I, Type II, Type III, and Type V ML. The results indicate a preference for Type II ML under deficient data support. Type III ML can effectively utilize field data, potentially generating more robust predictions than Type I and Type II ML. CNN-based closures exhibit more predictability than FNN-based closures, but CNN-based closures require more training data to obtain accurate predictions. Second, we illustrate how to employ Type I ML and Type II ML frameworks for data-driven turbulence modeling using reference works. Third, we demonstrate Type I ML by building a deep FNN-based slip closure for two-phase flow modeling. The results show that deep FNN-based closures exhibit a bounded error in the prediction domain.
DA - 2019/1//
PY - 2019/1//
DO - 10.1016/j.ijthermalsci.2018.09.002
VL - 135
SP - 559-579
SN - 1778-4166
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85054594382&partnerID=MN8TOARS
KW - Thermal fluid simulation
KW - Closure relations
KW - Multiscale modeling
KW - Machine learning framework
KW - Deep learning
KW - Data driven
KW - Convolutional neural networks
KW - Classification
ER -
TY - JOUR
TI - Further development of methodology to model TRISO fuel and BISO absorber particles and related uncertainty quantification using SCALE 6
AU - Sihlangu, S.F.
AU - Naicker, V.V.
AU - Hou, J.
AU - Reitsma, F.
T2 - Journal of Nuclear Science and Technology
AB - In the 350 MW Modular High Temperature Gas-Cooled Reactor (MHTGR-350), not only is the fuel double heterogeneous but so are the lumped burnable poisons (LBPs). The LBPs are composed of Bi-Structural Isotropic (BISO) particles and the fuel is composed of Tri-Structural Isotropic (TRISO) particles. This work investigates different methods to model coated particles using KENO-VI and NEWT of SCALE 6.The most efficient way of modelling TRISO particles in terms of packing and randomization is established in continuous energy (CE) mode and its impact on kinf is investigated.In the multi-group (MG) treatment, coated particles are modelled with the DOUBLEHET function which is only designed for particles that contain fuel. The LBP BISO particles could therefore not be modelled. Hence a method called the LBP Trace method is developed to model the LBP BISO particles using the DOUBLEHET function. It was found that kinf changed by 1500 pcm compared to the conventional (homogenized) case, when using the LBP Trace method. However, no significant change was observed in the macroscopic absorption cross section that would be passed to a nodal core calculation. Furt hermore, the LBP Trace method showed small changes in the nuclear data uncertainty when compared to conventional case.
DA - 2019/8/3/
PY - 2019/8/3/
DO - 10.1080/00223131.2019.1617204
VL - 56
IS - 8
SP - 690-709
UR - https://doi.org/10.1080/00223131.2019.1617204
KW - Double-heterogeneity
KW - DOUBLEHET
KW - coated fuel particle
KW - HTGR
KW - uncertainty
KW - SCALE 6
KW - burnable poison
KW - criticality analysis
KW - packing
KW - randomization
ER -
TY - JOUR
TI - Uncertainty Quantification and Propagation of Multiphysics Simulation of the Pressurized Water Reactor Core
AU - Zeng, Kaiyue
AU - Hou, Jason
AU - Ivanov, Kostadin
AU - Jessee, Matthew Anderson
T2 - Nuclear Technology
AB - In recent years, the demand to provide best-estimate predictions with confident bounds is increasing for the nuclear reactor performance and safety analysis. The Organisation for Economic Co-operation and Development Nuclear Energy Agency has been developing an international benchmark of the light water reactor (LWR) uncertainty analysis in modeling (UAM) for the examination of uncertainty quantification and propagation methodologies with various modeling and simulation code systems. The objective of the present work is to develop an uncertainty propagation mechanism based on the stochastic sampling method by taking into account the uncertainties of both basic nuclear data and fuel modeling parameters in the simulation of pressurized water reactors (PWRs) that can be incorporated in the conventional LWR simulation approach. More specifically, the Three Mile Island Unit 1–related exercises from the LWR-UAM benchmark have been modeled using the coupled TRACE/PARCS code system in the three-dimensional core representation. The input uncertainties of the neutronics simulation include few-group cross sections and kinetics parameters generated using the Sampler/Polaris sequence of SCALE 6.2.1. Several heat transfer–related variables for the fuel modeling were considered as sources of input uncertainty of the thermal-hydraulics simulations, including the thermal conductivity of fuel and cladding, fuel heat capacity, and the gap conductance. Dakota was used to sample input parameters of the coupled code system and to perform the uncertainty analysis. Two types of simulations were conducted: steady-state calculation at hot full-power condition and transient scenario initiated by the spatially asymmetric rod ejection accident. Quantities of interest for the steady-state calculation, including core multiplication factor and power peaking factors, were calculated with associated uncertainties. For transient calculations, best-estimate plus uncertainty results of the time evolution of core reactivity, core power, and peak fuel temperature were generated and analyzed. The Wilks’ formula was used to determine the necessary sample size to achieve a 95% confidence of the 95% limit of output quantities of interest. Although the uncertainty propagation and quantification method presented in this paper was developed for PWRs, it could be in general applicable to the multiphysics uncertainty quantification of other types of LWR cores.
DA - 2019/3/25/
PY - 2019/3/25/
DO - 10.1080/00295450.2019.1580533
VL - 205
IS - 12
SP - 1618-1637
J2 - Nuclear Technology
LA - en
OP -
SN - 0029-5450 1943-7471
UR - http://dx.doi.org/10.1080/00295450.2019.1580533
DB - Crossref
KW - Uncertainty quantification
KW - stochastic sampling
KW - PWR
KW - rod ejection accident
KW - multiphysics simulation
ER -
TY - JOUR
TI - Development of a New Contact Angle Control Algorithm for Level-Set Method
AU - Li, Mengnan
AU - Zeng, Kaiyue
AU - Wonnell, Louis
AU - Bolotnov, Igor A.
T2 - JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME
AB - A contact angle control algorithm is developed and implemented in the multiphase interface tracking flow solver—phasta. The subgrid force model is introduced to control the evolving contact angle. The contact angle force is applied when the current contact angle deviates from the desired value (or range of values) and decreases to zero when it reaches the desired value. The single bubble departure simulation and the capillary flat plates simulation are performed for verification purpose. The numerical results are compared with the analytical solution with good agreement. The mesh resolution sensitivity analysis and parametric study are conducted for both simulations. Coupled with the other existing capabilities in phasta like evaporation and condensation algorithm, the contact angle control algorithm will allow us to investigate the boiling phenomenon in various conditions with lower cost (by utilizing localized mesh refinement for bubble growth region) compared to uniformly refined structured meshes and in engineering geometries.
DA - 2019/6//
PY - 2019/6//
DO - 10.1115/1.4041987
VL - 141
IS - 6
SP -
SN - 1528-901X
ER -
TY - JOUR
TI - Nitrosylation vs. oxidation – How to modulate cold physical plasmas for biological applications
AU - Lackmann, Jan-Wilm
AU - Bruno, Giuliana
AU - Jablonowski, Helena
AU - Kogelheide, Friederike
AU - Offerhaus, Björn
AU - Held, Julian
AU - Gathen, Volker Schulz-von
AU - Stapelmann, Katharina
AU - Woedtke, Thomas
AU - Wende, Kristian
T2 - PLOS ONE
AB - Thiol moieties are major targets for cold plasma-derived nitrogen and oxygen species, making CAPs convenient tools to modulate redox-signaling pathways in cells and tissues. The underlying biochemical pathways are currently under investigation but especially the role of CAP derived RNS is barely understood. Their potential role in protein thiol nitrosylation would be relevant in inflammatory processes such as wound healing and improving their specific production by CAP would allow for enhanced treatment options beyond the current application. The impact of a modified kINPen 09 argon plasma jet with nitrogen shielding on cysteine as a thiol-carrying model substance was investigated by FTIR spectroscopy and high-resolution mass spectrometry. The deposition of short-lived radical species was measured by electron paramagnetic resonance spectroscopy, long-lived species were quantified by ion chromatography (NO2-, NO3-) and xylenol orange assay (H2O2). Product profiles were compared to samples treated with the so-called COST jet, being introduced by a European COST initiative as a reference device, using both reference conditions as well as conditions adjusted to kINPen gas mixtures. While thiol oxidation was dominant under all tested conditions, an Ar + N2/O2 gas compositions combined with a nitrogen curtain fostered nitric oxide deposition and the desired generation of S-nitrosocysteine. Interestingly, the COST-jet revealed significant differences in its chemical properties in comparison to the kINPen by showing a more stable production of RNS with different gas admixtures, indicating a different •NO production pathway. Taken together, results indicate various chemical properties of kINPen and COST-jet as well as highlight the potential of plasma tuning not only by gas admixtures alone but by adjusting the surrounding atmosphere as well.
DA - 2019/5/8/
PY - 2019/5/8/
DO - 10.1371/journal.pone.0216606
VL - 14
IS - 5
SP - 1 - 25
UR - https://doi.org/10.1371/journal.pone.0216606
ER -
TY - JOUR
TI - TREAT M2 experiment modeling for transient benchmark analysis
AU - Sorrell, Nina C.
AU - Hawari, Ayman I.
T2 - ANNALS OF NUCLEAR ENERGY
AB - The Transient Reactor Test Facility (TREAT) is a graphite moderated, air-cooled reactor historically operated for experimental fuel transient testing. This facility has returned to operation, and as part of that effort, the ability to model and predict the conditions for upcoming experiments is paramount to the development of the next generation of transient experiments and fuel testing. In order to design future experiments, methods are being developed to predictively reproduce data from experiments performed at TREAT prior to its shutdown in 1994. In this work, the M2 and M3 experiments, representing a set of transient tests, were selected to explore as TREAT transient benchmarks. In TREAT, transients are controlled largely by control/transient rod movement and temperature feedback that is attributed to the core’s graphite-fuel matrix. To capture these effects, a methodology for modeling these mechanisms using multi-physics coupled Monte Carlo simulations is developed. This includes performing full-core transient simulations using the Serpent Monte Carlo code with feedback based on temperature estimates derived from the OpenFOAM computational fluid dynamics code. Using this methodology, the developed model for the TREAT reactor was able to reproduce the pre-transient power maneuver from low power up to 27 MW and to initiate the power transient for the M2 2580 experiment. The results demonstrate the utility of this approach for dynamic modeling of the reactor. Additional investigation of the impact of key phenomena such as neutron thermalization and temperature response in TREAT’s graphitic core and the surrounding reflector was also performed under steady state conditions using the developed models.
DA - 2019/6//
PY - 2019/6//
DO - 10.1016/j.anucene.2019.01.026
VL - 128
SP - 398-405
SN - 0306-4549
KW - TREAT
KW - Transient
KW - Monte Carlo
KW - Graphite
ER -
TY - JOUR
TI - Assessment of thermal neutron scattering in a heavy paraffinic molecular material
AU - Manring, Cole A.
AU - Hawaii, Ayman I.
T2 - ANNALS OF NUCLEAR ENERGY
AB - Base oil lubricants are prevalent in many mechanical systems and can have a wide range of chemical compositions. Their carbon numbers generally span from C20–40, and they are often classified by their predominant molecular species (e.g., paraffinic, naphthenic). These heavy, viscous fluids are of interest when used in or around nuclear fuel cycle facilities, where they may influence the local neutronic environment. Furthermore, variations in molecular structure impact the oil’s dynamic properties and render the modeling process a challenging endeavor. In this work, a model for a specific paraffinic oil was developed for obtaining the vibrational/translational density of states (DOS) for hydrogen and carbon, the primary and secondary scattering species, respectively. The DOS was subsequently used to generate the thermal scattering law (TSL). The molecular ensemble, constructed using the MedeA material design platform, was benchmarked using available static and dynamic properties (i.e., density, viscosity, viscosity index, diffusivity). All simulations were performed using the LAMMPS code, and the COMPASS force field, a semi-empirical molecular potential, was selected as a suitable representation of the system dynamics. Additionally, a modified version of the nuclear data processing code, NJOY, was employed to more accurately treat a viscous fluid. Through this investigation, the viscous behavior characteristic of a heavy paraffinic oil was captured and was found to minimally impact the TSL when compared to the solid approximation.
DA - 2019/6//
PY - 2019/6//
DO - 10.1016/j.anucene.2018.12.042
VL - 128
SP - 140-147
SN - 0306-4549
KW - Thermal scattering law
KW - Viscous fluid
KW - Diffusion
ER -
TY - JOUR
TI - Environmental effect on mechanical properties of a gamma-prime strengthened nickel-based alloy: Effect of the surface oxidation and formation of gamma-prime free zones
AU - Marsh, Christopher
AU - Schoell, Ryan
AU - Kaoumi, Djamel
T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
AB - The mechanical behavior of X-750 in rough vacuum environment was explored and compared with the mechanical behavior in air at a large range of temperatures (from room temperature to 900°C) for both Heat-Treated and Non-Heat-Treated X750 alloy. In the intermediate range of temperatures where the Portevin Le Chatelier (PLC) effect is observed, the effect of testing in air versus rough vacuum did not yield statistically significant different PLC characteristics. At temperatures above 650°C for Heat Treated and 750°C for Non-Heat-Treated X-750, the samples tested under rough vacuum had higher yield stress values than the respective samples tested under air. The decrease in yield stress under air was attributed to an oxide scale induced surface softening effect and the loss of strengthening efficiency for the gamma prime precipitates. At higher temperatures in air, around 800°-900°C, sinusoidal stress serrations in the stress strain curves indicated the occurrence of dynamic recrystallization (DRX). The vacuum environment however removed all stress serrations attributed to DRX, indicating that the surface oxidation with the concomitant formation of a γ’ free zone underneath the oxide layer plays a role in the DRX presence.
DA - 2019/4/3/
PY - 2019/4/3/
DO - 10.1016/j.msea.2019.03.013
VL - 752
SP - 136-144
SN - 1873-4936
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85062646666&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Application of deconvolution to recover frequency-domain multiplexed detector pulses
AU - Mishra, M.
AU - Mattingly, J.
AU - Kolbas, R. M.
T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
AB - Multiplexing of radiation detectors reduces the number of readout channels, which in turn reduces the number of digitizer input channels for data acquisition. We recently demonstrated frequency domain multiplexing (FDM) of pulse mode radiation detectors using a resonator that converts the detector signal into a damped sinusoid by convolution. The detectors were given unique "tags" by the oscillation frequency of each resonator. The charge collected and the time-of-arrival of the detector pulse were estimated from the corresponding resonator output in the frequency domain. In this paper, we demonstrate a new method to recover the detector pulse from the damped sinusoidal output by deconvolution. Deconvolution converts the frequency-encoded detector signal back to the original detector pulse. We have developed a new prototype FDM system to multiplex organic scintillators based on convolution and deconvolution. Using the new prototype, the charge collected under the anode pulse can be estimated from the recovered pulse with an uncertainty of about 4.4 keVee (keV electron equivalent). The time-of-arrival can be estimated from the recovered pulse with an uncertainty of about 102 ps. We also used a CeBr3 inorganic scintillator to measure the Cs-137 gamma spectrum using the recovered pulses and found a standard deviation of 13.8 keV at 662 keV compared to a standard deviation of 13.5 keV when the original pulses were used. Coincidence measurements with Na-22 using the deconvolved pulses resulted in a timing uncertainty of 617 ps compared to an uncertainty of 603 ps using the original pulses. Pulse shape discrimination was also performed using Cf-252 source and EJ-309 organic scintillator pulses recovered by deconvolution. A figure of merit value of 1.08 was observed when the recovered pulses were used compared to 1.2 for the original pulses.
DA - 2019/6/11/
PY - 2019/6/11/
DO - 10.1016/j.nima.2019.03.043
VL - 929
SP - 57-65
SN - 1872-9576
KW - Frequency domain multiplexing
KW - Convolution/deconvolution
KW - Organic scintillators
KW - CeBr3 inorganic scintillators
ER -
TY - JOUR
TI - Experimental and theoretical investigation of crystallography and variant selection during massive transformation in Zr alloy
AU - Wang, J. M.
AU - Luan, B. F.
AU - Xin, R. L.
AU - Xing, Q. F.
AU - Murty, K. L.
AU - Cayron, C.
AU - Liu, Q.
T2 - PHILOSOPHICAL MAGAZINE
AB - Massive transformation, as a non-conventional solid-state phase transformation mode, is scarcely observed in metals with hexagonal closed packed (HCP) structure, especially in Zr and its alloys. In this study, however, we report the massive transformation in a Zr-1.0Cr-0.4Fe alloy after conventional β-quenching. It is shown that the necessary condition to induce the occurrence of massive transformation requires an appropriate composition and cooling rate of the alloy to be simultaneously within reasonable ranges. We combine the electron backscatter diffraction (EBSD) and crystallographic reconstruction techniques to systematically assess the orientation relationship between massive grain (αm) and its β parent grain. It is demonstrated that, similar to martensitic transformation, the orientation between αm and β parent grain during massive transformation satisfies Burgers orientation relationship, i.e. {110}β∥{0001}αm and <111>β∥<112¯0>αm. Furthermore, a statistical analysis of EBSD data shows that variant selection occurs during massive transformation due to pre-existing β-β grain boundary. Based on mathematical theory and crystallographic calculations, we further explore the detailed mechanisms of variant selection during massive transformation.
DA - 2019/5/19/
PY - 2019/5/19/
DO - 10.1080/14786435.2019.1574408
VL - 99
IS - 10
SP - 1163-1183
SN - 1478-6443
KW - Zr-Cr-Fe alloy
KW - massive transformation
KW - variant selection
KW - Burgers orientation relationship
ER -
TY - JOUR
TI - Serrated yielding in an advanced stainless steel Fe-25Ni-20Cr (wt%)
AU - Alomari, Abdullah S.
AU - Kumar, N.
AU - Murty, K. L.
T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
AB - Understanding serrated yielding behavior resulting from dynamic strain aging (DSA) is essential for design and safety considerations. In this work, uniaxial tensile tests were carried out at temperatures ranging from 298 to 1073 K and strain rates 10−5 – 10−3 s−1 followed by microstructural examination of Fe-25Ni-20Cr (wt%) austenitic stainless steel (Alloy 709), a candidate structural material for Sodium-cooled Fast Reactors. Serrated yielding was found to occur in this alloy in two temperature regimes; low-temperature serrated flow (LT-SF) from 498 to 648 K and high-temperature serrated flow (HT-SF) from 648 to 973 K (depending on the strain rate) with activation energies of 103 ± 13 kJ/mole and 204 ± 11 kJ/mole respectively. The critical strain for the occurrence of serrations was found to increase with strain rate as an exponential function with exponent (m + β) of 0.78 ± 0.1 and 1.56 ± 0.2 for the LT-SF and HT-SF regimes respectively. Based on the activation energies and m + β values, diffusion of interstitial atoms has been suggested to be responsible for serrated flow in the LT-SF regime while Cr atom migration was inferred to be responsible for DSA in the HT-SF regime. Manifestations of DSA in the Alloy 709 were observed including peaks and/or plateaus in flow stresses along with negative strain rate sensitivity at intermediate temperatures. However, no loss in ductility was observed within DSA regime attributed to the relatively high work hardening rate and strain-hardening exponent. The samples deformed in DSA regime showed planar substructure while equiaxed subgrains formed at higher temperatures. The fraction of low angle grain boundaries after deformation exhibited a valley at intermediate temperatures believed to be another manifestation of the DSA.
DA - 2019/3/28/
PY - 2019/3/28/
DO - 10.1016/j.msea.2019.02.023
VL - 751
SP - 292-302
SN - 1873-4936
KW - Serrated flow
KW - Dynamic strain aging
KW - High temperature deformation
KW - Austenitic steels
ER -
TY - JOUR
TI - Phonon dispersion using the ratio of zero-time correlations among conjugate variables: Computing full phonon dispersion surface of graphene
AU - Raj, Anant
AU - Eapen, Jacob
T2 - COMPUTER PHYSICS COMMUNICATIONS
AB - We present a robust family of methods (ZTR) to compute the phonon dispersion curves based on the ratio of zero-time correlations of conjugate variables in the reciprocal space. This general technique extracts the normal mode frequency corresponding to wave vector q and polarization p, from the ratio of the correlation of the nth derivative of displacement to the n-1th derivative in reciprocal space at zero time. A particular version of this method using the ratio of velocity to displacement (n=1) is previously known but seldom employed in atomistic simulations. For n=2, the method involves velocities and accelerations — dynamical variables that are more well-defined than equilibrium displacements in atomistic simulations. We test the ZTR methods and demonstrate that both ZTR methods (n=1,2) can accurately resolve the phonon mode frequencies while offering a significant improvement to the computational speed. We also illustrate the ability of the ZTR methods to handle anharmonicity and phonon softening at high temperatures. Finally, we demonstrate the power of the ZTR approach by computing the full phonon dispersion surface for graphene across the entire Brillouin zone with 3600 wave vectors and six polarizations at finite temperatures — a challenging task for the traditional methods.
DA - 2019/5//
PY - 2019/5//
DO - 10.1016/j.cpc.2018.12.008
VL - 238
SP - 124-137
SN - 1879-2944
KW - Phonon dispersion
KW - Graphene
KW - Lattice Dynamics
KW - Simulations
KW - Thermal Conductivity
KW - Nanoscale
ER -
TY - JOUR
TI - High-precision characterization of the neutron light output of stilbene along the directions of maximum and minimum response
AU - Weldon, R. A., Jr.
AU - Mueller, J. M.
AU - Lynch, C.
AU - Schuster, P.
AU - Hedges, S.
AU - Awe, C.
AU - Li, L.
AU - Barbeau, P.
AU - Mattingly, J.
T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
AB - The scintillation light output response of stilbene crystals has been measured for protons recoiling along the a, b, and c’ crystalline axes with energies between 1.3 and 10 MeV using neutrons produced with the tandem Van de Graaff accelerator at Triangle Universities Nuclear Laboratory. The proton recoil energy and direction were measured using the coincident detection of neutrons between a stilbene scintillator and an array of EJ-309 liquid scintillators spanning arranged neutron recoil angles. The maximum light output was found to coincide with proton recoils along the a-axis, in disagreement with other published measurements, which reported the b-axis as the direction of the maximum light output. Additional measurements were conducted using two different stilbene crystals to confirm these results: a second measurement using the coincident detection of neutrons; measurements of neutron full energy deposition events along the a and b axes; and measurements of the count rate for 252Cf neutrons traveling along the a and b axes directions. All measurements found that recoils along the a-axis produce the maximum light output.
DA - 2019/5/21/
PY - 2019/5/21/
DO - 10.1016/j.nima.2018.10.075
VL - 927
SP - 313-319
SN - 1872-9576
KW - Stilbene
KW - Scintillation anisotropy
KW - Crystalline organic scintillator
KW - Neutron detection
KW - Detector characterization
ER -
TY - JOUR
TI - Interplay Between Grain Boundaries and Radiation Damage
AU - Barr, Christopher M.
AU - El-Atwani, Osman
AU - Kaoumi, Djamel
AU - Hattar, Khalid
T2 - JOM
DA - 2019/4//
PY - 2019/4//
DO - 10.1007/s11837-019-03386-y
VL - 71
IS - 4
SP - 1233-1244
SN - 1543-1851
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85062726933&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Design and Operation of a Sensible Heat Peaking Unit for Small Modular Reactors
AU - Frick, Konor
AU - Doster, J. Michael
AU - Bragg-Sitton, Shannon
T2 - NUCLEAR TECHNOLOGY
AB - Approximately 19% of the electricity produced in the United States comes from nuclear power plants. Traditionally, nuclear power plants, as well as larger coal-fired plants, operate in a baseload manner at or near steady state for prolonged periods of time. Smaller, more maneuverable plants, such as gas-fired plants, are dispatched to match electricity supply and demand above the capacity of the baseload plants. However, air quality concerns and CO2 emission standards have made the burning of fossil fuels less desirable, despite the current low cost of natural gas. Wind and solar photovoltaic power generation are attractive options due to their lack of carbon footprint and falling capital costs. Yet, these renewable energy sources suffer from inherent intermittency. This inherent intermittency can strain electric grids, forcing carbon-based and nuclear sources of energy to operate in a load-follow mode. For nuclear reactors, load-follow operation can be undesirable due to the associated thermal and mechanical stresses placed on the fuel and other reactor components. Various methods of thermal energy storage (TES) can be coupled to nuclear (or renewable) power sources to help absorb grid variability caused by daily load demand changes and renewable intermittency. Our previous research has shown that coupling a sensible heat TES system to a small modular reactor allows the reactor to run at effectively nominal full power during periods of variable electric demand by bypassing steam to the TES system during periods of excess capacity. In this paper we demonstrate that this stored thermal energy can be recovered, allowing the TES system to act as a peaking unit during periods of high electric demand or used to produce steam for ancillary applications such as desalination. For both applications the reactor is capable of operating continuously at approximately 100% power.
DA - 2019///
PY - 2019///
DO - 10.1080/00295450.2018.1491181
VL - 205
IS - 3
SP - 415-441
SN - 1943-7471
KW - Thermal energy storage
KW - small modular reactor
KW - integral pressurized water reactor
KW - nuclear-hybrid energy system
ER -
TY - JOUR
TI - A comparative study on the neutron-gamma density and gamma-gamma density logging
AU - Zhang, Quanying
AU - Zhang, Feng
AU - Yuan, Chao
AU - Wang, Xinguang
AU - Zhang, Xiaoyang
T2 - JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
AB - Abstract With the increasing demand for the radioisotope-free operations, using pulsed neutron gamma density (NGD) instead of gamma-gamma density (GGD) has become increasingly important for the development of logging while drilling (LWD) technology. However, due to the different logging mechanisms, there are huge differences between GGD and NGD in the instrument designs, measurement methods, and instrument specifications. To further promote the NGD development, a comparative study on GGD and NGD was carried out from theoretical and simulation aspects. Based on the theoretical methods, the differences between GGD and NGD in the gamma sources, field distribution, methods for density measurement and instrument specifications were systematically elaborated. Then, using the Monte Carlo simulation, the GGD and NGD models were built to quantitatively verify the theoretical results. Last, the detailed performances of NGD and GGD methods in different logging environments were compared. Results showed that the theoretical results are highly consistent with the simulation results. The density sensitivity of NGD is less than half that of GGD, but the depth of investigation (DOI) approaches twice that of GGD. The density precision and vertical resolution of NGD are less than those of GGD. Additionally, compared to GGD, NGD also has an excellent performance in different pore fluid and lithology formations, but it is easily affected by borehole factors. The research can provide quantitative performance evaluations for the NGD replacing GGD in LWD logging.
DA - 2019/5//
PY - 2019/5//
DO - 10.1016/j.petrol.2019.02.007
VL - 176
SP - 792-799
SN - 1873-4715
KW - Pulsed neutron gamma density
KW - Gamma-gamma density
KW - Logging mechanism
KW - Monte Carlo simulation
KW - Instrument specifications
ER -
TY - JOUR
TI - Low-Pressure Plasma Sterilization for Test Specimens to be Worn on Splints in the Oral Cavity
AU - Naumova, Ella A.
AU - Engel, Alexander-Simon
AU - Kranz, Hagen Tizian
AU - Schneider, Marvin
AU - Tietze, Jan
AU - Dittmar, Thomas
AU - Fiebrandt, Marcel
AU - Stapelmann, Katharina
AU - Piwowarczyk, Andree
AU - Kuczius, Thorsten
AU - Arnold, Wolfgang H.
T2 - COATINGS
AB - Bacterial biofilms adhere to all oral surfaces and may alter or degrade them. For investigations of the oral biofilm, growing on new restorative dental biomaterials, sterilized dental enamel surfaces as natural, control, and reference materials are used. A novel method for disinfection and sterilization of surfaces is low-pressure plasma (LPP) sterilization, which is a nondestructive and nontoxic technology. The roughness of the dental enamel surface was determined before and after LPP sterilization. Enamel discs were placed in dental splints and worn for five days in vivo. Oral biofilm was fixed for scanning electron microscopy (SEM). Biofilms growing in vitro were characterized microbiologically before and after sterilization and examined by confocal laser scanning microscopy (CLSM). Microbiology demonstrated that various bacterial strains were present in the biofilms. SEM showed multiple layers of densely packed bacteria, and CLSM demonstrated that the biofilm contained live and dead bacteria. After LPP sterilization, no biofilm could be detected, and the enamel surface remained unaltered. It may be concluded that LPP sterilization is an effective, nondestructive method for disinfection of enamel before application in the oral cavity. LPP sterilization may be suitable for sterilization of dental materials without altering their surfaces.
DA - 2019/2//
PY - 2019/2//
DO - 10.3390/coatings9020099
VL - 9
IS - 2
SP -
SN - 2079-6412
KW - plasma
KW - sterilization
KW - biofilm
KW - oral biofilm
ER -
TY - JOUR
TI - Investigation of the Corrosion Behavior of Atomic Layer Deposited Al2O3/TiO2 Nanolaminate Thin Films on Copper in 0.1 M NaCl
AU - Fusco, Michael A.
AU - Oldham, Christopher J.
AU - Parsons, Gregory N.
T2 - MATERIALS
AB - Fifty nanometers of Al₂O₃ and TiO₂ nanolaminate thin films deposited by atomic layer deposition (ALD) were investigated for protection of copper in 0.1 M NaCl using electrochemical techniques. Coated samples showed increases in polarization resistance over uncoated copper, up to 12 MΩ-cm², as measured by impedance spectroscopy. Over a 72-h immersion period, impedance of the titania-heavy films was found to be the most stable, as the alumina films experienced degradation after less than 24 h, regardless of the presence of dissolved oxygen. A film comprised of alternating Al₂O₃ and TiO₂ layers of 5 nm each (referenced as ATx5), was determined to be the best corrosion barrier of the films tested based on impedance spectroscopy measurements over 72 h and equivalent circuit modeling. Dissolved oxygen had a minimal effect on ALD film stability, and increasing the deposition temperature from 150 °C to 250 °C, although useful for increasing film quality, was found to be counterproductive for long-term corrosion protection. Implications of ALD film aging and copper-based surface film formation during immersion and testing are also discussed briefly. The results presented here demonstrate the potential for ultra-thin corrosion barrier coatings, especially for high aspect ratios and component interiors, for which ALD is uniquely suited.
DA - 2019/2/2/
PY - 2019/2/2/
DO - 10.3390/ma12040672
VL - 12
IS - 4
SP -
SN - 1996-1944
KW - atomic layer deposition
KW - corrosion protection
KW - copper
KW - aluminum oxide
KW - titanium oxide
KW - nanolaminate
KW - electrochemical impedance spectroscopy
KW - barrier coatings
ER -
TY - JOUR
TI - Complex transients in power modulated inductively-coupled chlorine plasmas
AU - List, Tyler
AU - Ma, Tianyu
AU - Arora, Priyanka
AU - Donnelly, Vincent M
AU - Shannon, Steven
T2 - Plasma Sources Science and Technology
AB - Time-dependent studies of power-modulated chlorine inductively-coupled plasmas are presented. Power at 13.56 MHz applied to the plasma was modulated between high and low power states. Time-resolved optical emission, power delivery, and Langmuir probe measurements revealed at least two conditions upon switching from high to low power: a 'normal' mode in which electron temperature (Te) remains constant, while electron and ion number densities (ne and n+) and optical emission spectroscopic (OES) intensities smoothly drop to a level roughly equal to the fractional drop in power, and an 'abnormal' mode in which ne, n+ and OES intensities plummet before the plasma re-ignites and these values rise to levels more commensurate with the drop in power. Whether the plasma operates in the normal or abnormal mode is sensitive to impedance matching conditions and is also a function of pressure and pulsing parameters. This ignition delays in the abnormal mode can be qualitatively understood in terms of a power balance model commonly used to explain instability-induced, self-modulation in highly electronegative plasmas, caused by the slower time response of negative ions compared with electrons. The study indicates that power modulation for added control in processes such as plasma etching will require careful measurement and possibly control of power with microsecond resolution.
DA - 2019/2/25/
PY - 2019/2/25/
DO - 10.1088/1361-6595/ab000c
VL - 28
IS - 2
SP - 025005
J2 - Plasma Sources Sci. Technol.
OP -
SN - 1361-6595
UR - http://dx.doi.org/10.1088/1361-6595/ab000c
DB - Crossref
KW - pulsed plasmas
KW - chlorine plasmas
KW - instabilities
KW - electronegative plasmas
KW - capacitive to inductive transitions
ER -
TY - JOUR
TI - A Monte Carlo feasibility study for neutron based real-time range verification in proton therapy
AU - Ytre-Hauge, Kristian Smeland
AU - Skjerdal, Kyrre
AU - Mattingly, John
AU - Meric, Ilker
T2 - SCIENTIFIC REPORTS
AB - Abstract Uncertainties in the proton range in tissue during proton therapy limit the precision in treatment delivery. These uncertainties result in expanded treatment margins, thereby increasing radiation dose to healthy tissue. Real-time range verification techniques aim to reduce these uncertainties in order to take full advantage of the finite range of the primary protons. In this paper, we propose a novel concept for real-time range verification based on detection of secondary neutrons produced in nuclear interactions during proton therapy. The proposed detector concept is simple; consisting of a hydrogen-rich converter material followed by two charged particle tracking detectors, mimicking a proton recoil telescopic arrangement. Neutrons incident on the converter material are converted into protons through elastic and inelastic (n,p) interactions. The protons are subsequently detected in the tracking detectors. The information on the direction and position of these protons is then utilized in a new reconstruction algorithm to estimate the depth distribution of neutron production by the proton beam, which in turn is correlated with the primary proton range. In this paper, we present the results of a Monte Carlo feasibility study and show that the proposed concept could be used for real-time range verification with millimetric precision in proton therapy.
DA - 2019/2/14/
PY - 2019/2/14/
DO - 10.1038/s41598-019-38611-w
VL - 9
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Role of selenium addition to CdZnTe matrix for room-temperature radiation detector applications
AU - Roy, U. N.
AU - Camarda, G. S.
AU - Cui, Y.
AU - Gul, R.
AU - Hossain, A.
AU - Yang, G.
AU - Zazvorka, J.
AU - Dedic, V.
AU - Franc, J.
AU - James, R. B.
T2 - SCIENTIFIC REPORTS
AB - Abstract Because of its ideal band gap, high density and high electron mobility-lifetime product, cadmium zinc telluride (CdZnTe or CZT) is currently the best room-temperature compound-semiconductor X- and gamma-ray detector material. However, because of its innate poor thermo-physical properties and above unity segregation coefficient for Zn, the wide spread deployment of this material in large-volume CZT detectors is still limited by the high production cost. The underlying reason for the low yield of high-quality material is that CZT suffers from three major detrimental defects: compositional inhomogeneity, high concentrations of dislocation walls/sub-grain boundary networks and high concentrations of Te inclusions/precipitates. To mitigate all these disadvantages, we report for the first time the effects of the addition of selenium to the CZT matrix. The addition of Se was found to be very effective in arresting the formation of sub-grain boundaries and its networks, significantly reducing Zn segregation, improving compositional homogeneity and resulting in much lower concentrations of Te inclusions/precipitates. Growth of the new quaternary crystal Cd 1−x Zn x Te 1−y Se y (CZTS) by the Traveling Heater Method (THM) is reported in this paper. We have demonstrated the production of much higher yield according to its compositional homogeneity, with substantially lower sub-grain boundaries and their network, and a lower concentration of Te inclusions/precipitates.
DA - 2019/2/7/
PY - 2019/2/7/
DO - 10.1038/s41598-018-38188-w
VL - 9
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Correlation of in-situ transmission electron microscopy and microchemistry analysis of radiation-induced precipitation and segregation in ion irradiated advanced ferritic/martensitic steels
AU - Zheng, Ce
AU - Ke, Jia-Hong
AU - Maloy, Stuart A.
AU - Kaoumi, Djamel
T2 - SCRIPTA MATERIALIA
AB - This article presents a novel method combining ion irradiation, in-situ transmission electron microscopy (TEM), and microchemistry analysis before/after irradiation, which allows to examine same microstructural areas throughout ion irradiation. A 12 wt% Cr Ferritic/Martensitic steel (HT9) was irradiated in the TEM to 1.17 × 1020 ions·m−2 at 440 °C using 1 MeV Kr2+ ions, and the in-situ characterization focused on radiation-induced precipitation and segregation. Results of in-situ experiments were compared with those obtained from ex-situ experiments, to showcase how this method helps to better understand precipitation kinetics in the irradiated material examined ex-situ, for which only snapshots are available at limited doses.
DA - 2019/3/15/
PY - 2019/3/15/
DO - 10.1016/j.scriptamat.2018.12.018
VL - 162
SP - 460-464
SN - 1359-6462
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85058704067&partnerID=MN8TOARS
KW - Ferritic/martensitic steels
KW - Ion irradiation
KW - In-situ transmission electron microscopy
KW - Energy dispersive X-ray spectroscopy
KW - Precipitation
ER -
TY - JOUR
TI - Retrospective dosimetry at the natural background level with commercial surface mount resistors
AU - Hayes, Robert B.
AU - O'Mara, Ryan P.
T2 - Radiation Measurements
AB - A single aliquot regenerative (SAR) protocol utilizing thermoluminescence demonstrated precise and accurate retrospective dosimetry capability using common commercial surface mount resistors at levels able to discriminate the age of resistors based on background dose accrual. Detection limits below 10 mGy can be realized with this method having precision at the 1 Gy level in the range of only 3% which is substantially better than that required for emergency response dosimetry. Moreover, these dose estimates could be obtained in mere hours rather than current biodosimetry methods which can take weeks.
DA - 2019/2//
PY - 2019/2//
DO - 10.1016/j.radmeas.2018.12.007
VL - 121
SP - 42-48
J2 - Radiation Measurements
LA - en
OP -
SN - 1350-4487
UR - http://dx.doi.org/10.1016/j.radmeas.2018.12.007
DB - Crossref
KW - Thermoluminescence
KW - Emergency response
KW - Dosimetry
KW - Personnel monitoring
ER -
TY - JOUR
TI - Measurement of localized plasma perturbation with hairpin resonator probes
AU - Ford, Kristopher
AU - Peterson, David J.
AU - Brandon, Joel
AU - Nam, Sang Ki
AU - Walker, Dustin
AU - Shannon, Steven C.
T2 - Physics of Plasmas
AB - In situ plasma diagnostics present the classical problem of the scientific measurement: how does one accurately measure a system without also perturbing it? The uncertainty in the degree of perturbation then reflects an inherent uncertainty in the diagnostic results. Microwave probes are no exception. This work discusses an experimental methodology for quantifying the local perturbation in hairpin resonator probe measurements. By pulsing the delivered power to a plasma, an electron density hairpin spike (HS) is readily detected at generator shutoff. The phenomenon is understood to arise from an apparent density rise as the plasma sheath collapses, thus raising the spatially averaged density measured between the hairpin tines. Other explanations for the density rise are eliminated, and the utility of the HS is presented. Under the conditions investigated, the HS provides an experimental comparison to a previous sheath correction factor developed by Sands et al.
DA - 2019/1//
PY - 2019/1//
DO - 10.1063/1.5065509
VL - 26
IS - 1
SP - 013510
J2 - Physics of Plasmas
LA - en
OP -
SN - 1070-664X 1089-7674
UR - http://dx.doi.org/10.1063/1.5065509
DB - Crossref
ER -
TY - JOUR
TI - Growth of CdMnTe free of large Te inclusions using the vertical Bridgman technique
AU - Roy, U. N.
AU - Camarda, G. S.
AU - Cui, Y.
AU - Gul, R.
AU - Hossain, A.
AU - Yang, G.
AU - Okobiah, O. K.
AU - Egarievwe, S. U.
AU - James, R. B.
T2 - JOURNAL OF CRYSTAL GROWTH
AB - We grew Cd1-xMnxTe crystals with a nominal composition of 5% Mn and 95% Cd using the vertical Bridgman technique. We were able to grow crystals from as-received starting material that were free of secondary phases, such as Te inclusions with a size > 1-µm diameter, without adding compensating Cd to the initial charge. The Te precipitations (size < 1-µm diameter) were found to segregate towards the last-to-freeze section of the ingot. Te inclusions with a size 5–7 µm were observed at the grain boundary located near the last-to-freeze section, while the bottom and middle parts of the ingot showed no Te inclusions, even at the grain boundaries. X-ray topographic analysis was used to characterize the distribution of thermal stress in the ingot.
DA - 2019/3/1/
PY - 2019/3/1/
DO - 10.1016/j.jcrysgro.2018.12.026
VL - 509
SP - 35-39
SN - 1873-5002
KW - Characterization
KW - Extended defects
KW - Sub-grain boundary network
KW - Bridgman
KW - CdMnTe
KW - Semiconducting II-VI materials
ER -
TY - JOUR
TI - Creep Behavior and Microstructural Evolution of a Fe-20Cr-25Ni (Mass Percent) Austenitic Stainless Steel (Alloy 709) at Elevated Temperatures
AU - Alomari, Abdullah S.
AU - Kumar, N.
AU - Murty, K. L.
T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
DA - 2019/2//
PY - 2019/2//
DO - 10.1007/s11661-018-5044-y
VL - 50A
IS - 2
SP - 641-654
SN - 1543-1940
ER -
TY - JOUR
TI - Ion irradiation effects on commercial PH 13-8 Mo maraging steel Corrax
AU - Zheng, Ce
AU - Schoell, Ryan
AU - Hosemann, Peter
AU - Kaoumi, Djamel
T2 - JOURNAL OF NUCLEAR MATERIALS
AB - The effects of irradiation on the precipitation behavior of commercial PH 13-8 Mo maraging steel a.k.a. Corrax are investigated through in-situ ion irradiation. Samples of the alloy in its solution annealed state are irradiated up to 10 dpa at 573 and 773 K using 1 MeV Kr ions, in-situ in a transmission electron microscope in order to probe irradiation effects on the precipitation usually observed in this alloy under thermal aging. Indeed, the alloy is known to develop a relatively fine distribution of precipitates during thermal aging which gives the martensitic alloy its strength. The effects of irradiation are substantiated by comparing with the same material thermally aged at 773 and 873 K for similar amounts of experimental time. Both radiation and thermal aging induced segregation and precipitation are characterized using analytical transmission electron microscopy (TEM) techniques. The diffusion coefficients under irradiation are estimated using the point defect balance equations based on Rate Theory and then compared with the thermal diffusion coefficients, demonstrating the accelerated precipitation of β-phase and Laves-phase in the irradiation case at relatively lower temperature is attributed to the radiation-enhanced diffusion. In addition, a numerical model based on classical precipitate nucleation and growth theories is introduced and shows a relatively good agreement with the experimental results in terms of precipitate density. This study serves to generate baseline data on ion irradiation effects on Corrax to learn how this steel responds to irradiation.
DA - 2019///
PY - 2019///
DO - 10.1016/j.jnucmat.2018.11.041
VL - 514
SP - 255–265
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85058006280&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Rigid valence band shift due to molecular surface counter-doping of MoS2
AU - Nevola, D.
AU - Hoffman, B. C.
AU - Bataller, A.
AU - Ade, H.
AU - Gundogdu, K.
AU - Dougherty, D. B.
T2 - SURFACE SCIENCE
AB - Adsorption of the acceptor material tetracyanoquinodimethane can control optoelectronic properties of MoS2 by accepting defect generated excess negative charge from the surface that would otherwise interfere with radiative decay processes. Angle Resolved Photoelectron Spectroscopy measurements show that the MoS2 band structure near the Γ point shifts rigidly upward by ∼0.2 eV for a complete surface coverage of acceptor species as expected for an upward Fermi level shift due to charge transfer to the TCNQ. The molecular adsorbate orbitals visible in photoemission are indicative of an anionic species, consistent with interfacial charge transfer but without evidence for hybrid states arising from covalent adsorbate-surface interactions. Thus, our interface studies support the notion that molecular adsorbates are a useful tool for controlling optoelectronic functionality in 2D materials without fundamentally modifying their favorable band structures.
DA - 2019/1//
PY - 2019/1//
DO - 10.1016/j.susc.2018.09.016
VL - 679
SP - 254-258
SN - 1879-2758
ER -
TY - JOUR
TI - Study of deformation mechanisms in a metastable beta Zr alloy during compression
AU - Liao, Zhongni
AU - Luan, Baifeng
AU - Zhang, Xinyu
AU - Xing, Qingfeng
AU - Liu, Riping
AU - Murty, K. L.
AU - Liu, Qing
T2 - MATERIALS LETTERS
AB - The deformation mechanisms in a metastable β-48.1Zr-43.2Ti-4.5Al-4.2V (wt%) alloy after room-temperature compression to ∼6% strain were investigated. The results indicated that the alloy deforms primarily by deformation-induced β → α′ martensitic transformation and 101¯2<101¯1> twinning, and limited deformation-induced β → α″ martensitic transformation. The 101¯2<101¯1> twinning was formed within the α′ plate to accommodate the local plastic deformation strain generated in α′ martensite plate during compression. Such a combination of deformation mechanisms were observed in metastable β Zr or Ti alloys for the first time, which can aid future development of superior β Zr alloys displaying a potentially combination of transformation-induced plasticity (TRIP) and transformation twinning-induced plasticity (TWIP) effects.
DA - 2019/2/15/
PY - 2019/2/15/
DO - 10.1016/j.matlet.2018.11.043
VL - 237
SP - 172-175
SN - 1873-4979
KW - Deformation mechanisms
KW - Metastable beta-Zr alloy
KW - Deformation-induced martensitic
KW - transformation
KW - Twinning
ER -
TY - JOUR
TI - Implementation of the Monte Carlo Library Least-Squares (MCLLS) approach for quantification of the chlorine impurity in an on-line crude oil monitoring system
AU - Chang, Hao Ping
AU - Meric, Ilker
AU - Sudac, Davorin
AU - Nad, Karlo
AU - Obhodas, Jasmina
AU - Hou, Guojing
AU - Zhang, Yan
AU - Gardner, Robin P.
T2 - RADIATION PHYSICS AND CHEMISTRY
AB - Prompt gamma-ray neutron activation analysis (PGNAA) has been widely used for elemental analysis of bulk samples as it provides an on-line, rapid and non-destructive means of performing such analysis. The Monte Carlo Library Least-Squares (MCLLS) approach is one of the methods for quantitative analysis providing elemental weight fractions via an assumption that the total prompt gamma-ray spectrum is a linear combination of the contributions from the individual prompt gamma-ray spectra of the sample constituents. For the generation of prompt gamma-ray libraries of each constituent, a specific purpose Monte Carlo code system called Center for Engineering Applications of Radioisotopes Coincidence Prompt Gamma-Ray (CEARCPG) is utilized. In this work, the focus was on detecting and measuring chlorine impurity in crude oil samples, i.e. trace amounts of chlorine. A preliminary study investigating the feasibility of PGNAA method in conjunction with the MCLLS approach for measuring trace amounts of chlorine in oil samples was performed. For this purpose, an extended version of the MCLLS approach, the so-called MCLLSX approach, was proposed and applied for the quantitative analysis. The results presented in this paper prove the feasibility of the proposed approach.
DA - 2019/2//
PY - 2019/2//
DO - 10.1016/j.radphyschem.2018.05.012
VL - 155
SP - 197-201
SN - 0969-806X
KW - DT neutron generator
KW - PGNAA
KW - CEARCPG
KW - MCLLS/MCLLSX
KW - Crude oil
KW - Chlorine
ER -
TY - JOUR
TI - Bayesian Metropolis methods for source localization in an urban environment
AU - Hite, Jason
AU - Mattingly, John
T2 - RADIATION PHYSICS AND CHEMISTRY
AB - We apply Bayesian techniques to determine the location and intensity of a gamma radiation source in an urban environment using count rates taken from a distributed detector network. A simplified model of the radiation transport process is used to construct a statistical model for the detector count rates in the presence of a randomly varying background. Markov Chain Monte Carlo is used to generate samples from the Bayesian posterior density, which can be used to inform search and interdiction efforts. We also present a modification of the traditional Metropolis sampling algorithm that allows us to incorporate fixed parameter uncertainties in building macroscopic cross sections and account for their effects on the posterior distribution. This method is then applied to a test problem based on a real urban geometry with different levels of uncertainty in the building cross sections. The results show that the uncertainty in the estimated source location is modest, even with a large degree of uncertainty in the building cross sections.
DA - 2019/2//
PY - 2019/2//
DO - 10.1016/j.radphyschem.2018.06.024
VL - 155
SP - 271-274
SN - 0969-806X
ER -
TY - JOUR
TI - Uncertainty quantification for Gamma-ray spectroscopy using the Library-Least Squares technique
AU - Feinberg, Aaron
AU - Gardner, Robin P.
T2 - RADIATION PHYSICS AND CHEMISTRY
AB - This work explores aspects of uncertainty quantification for inverse gamma-ray problems that use the Library Least Squares method by analyzing a simple example. Two uncertainty quantification techniques (first-order propagation and forward Monte-Carlo) are used in this work. The effects of resolution are explored by comparing results found with NaI and HPGe detectors. These results are confounded with the effects of total counts and binning. A conclusion is established that in some, very-specific cases, there is no reduction in uncertainty from using better-resolution detectors. The limitations of this conclusion and of the uncertainty quantification techniques used are discussed at length.
DA - 2019/2//
PY - 2019/2//
DO - 10.1016/j.radphyschem.2018.08.015
VL - 155
SP - 191-196
SN - 0969-806X
KW - Uncertainty quantification
KW - Detector resolution
KW - Library least squares
KW - LLS
KW - Gamma-ray elemental analysis
KW - Binning
ER -
TY - JOUR
TI - A new fuel modeling capability, CTFFuel, with a case study on the fuel thermal conductivity degradation
AU - Toptan, Aysenur
AU - Salko, Robert K.
AU - Avramova, Maria N.
AU - Clarno, Kevin
AU - Kropaczek, David J.
T2 - NUCLEAR ENGINEERING AND DESIGN
AB - A new fuel modeling capability, CTFFuel, is developed from the subchannel code, CTF. This code is a standalone interface to the CTF fuel rod models, allowing for fuel rod simulations to be run independently from the fluid. This paper provides an overview of the code with a case study on the thermal conductivity degradation of LWR fuels to demonstrate its capabilities. The modeling of fuel thermal conductivity degradation in the code is improved through the addition of new modeling options to account for the irradiation effects via globally defined parameters. After the initial implementation, a variety of order-of-accuracy tests and code comparisons are performed to test software quality. A controlled analysis is allowed by CTFFuel to verify the numerical scheme of CTF’s conduction solution and to benchmark its fuel temperature predictions against FRAPCON-4.0’s. Overall, the software quality and verification procedure ensures that the new model is coded correctly, that it properly interacts with the rest of the code.
DA - 2019/1//
PY - 2019/1//
DO - 10.1016/j.nucengdes.2018.11.010
VL - 341
SP - 248-258
SN - 1872-759X
KW - CTFFuel
KW - Thermal conductivity degradation
KW - CTF
KW - SQA
KW - Verification
ER -
TY - JOUR
TI - Localization of a radioactive source in an urban environment using Bayesian Metropolis methods
AU - Hite, Jason
AU - Mattingly, John
AU - Archer, Dan
AU - Willis, Michael
AU - Rowe, Andrew
AU - Bray, Kayleigh
AU - Carter, Jake
AU - Ghawaly, James
T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
AB - Abstract We present a method for localizing an unknown source of radiation in an urban environment using a distributed detector network. This method employs statistical parameter estimation techniques, relying on an approximation for the response of a detector to the source based on a simplified model of the underlying transport phenomena, combined with a Metropolis-type sampler that is modified to propagate the effect of fixed epistemic uncertainties in the material macroscopic cross sections of objects in the scene. We apply this technique to data collected during a measurement campaign conducted in a realistic analog for an urban scene using a network of six mobile detectors. Our initial results are able to localize the source to within approximately 8 m over a scene of size 300 m × 200 m in two independent trials with 30 min count times, including a characterization of the uncertainty associated with the poorly known macroscopic cross sections of objects in the scene. In these measurements, the nearest detectors were between 20 m to 30 m from the source, and recorded count rates between approximately 3 and 13 times background. A few detectors had line-of-sight to the source, while the majority were obscured by objects present in the scene. After extending our model to account for the orientation of the detectors and correcting for anomalies in the measurement data we were able to further improve the localization accuracy to approximately 2 m in both trials.
DA - 2019/1/21/
PY - 2019/1/21/
DO - 10.1016/j.nima.2018.09.032
VL - 915
SP - 82-93
SN - 1872-9576
KW - Source localization
KW - Bayesian parameter estimation
KW - Sensor networks
ER -
TY - JOUR
TI - Stability analysis of a multilevel quasidiffusion method for thermal radiative transfer problems
AU - Anistratov, Dmitriy Y.
T2 - JOURNAL OF COMPUTATIONAL PHYSICS
AB - In this paper we analyze a multilevel quasidiffusion (QD) method for solving time-dependent multigroup nonlinear radiative transfer problems which describe interaction of photons with matter. The multilevel method is formulated by means of the high-order radiative transfer equation and a set of low-order moment equations. The fully implicit scheme is used to discretize equations in time. The stability analysis is applied to the method in semi-continuous and discretized forms. To perform Fourier analysis, the system of equations of the multilevel method is linearized about an equilibrium solution. The effects of discretization with respect to different independent variables are studied. The multilevel method is shown to be stable and fast converging. We also consider a version of the method in which time evolution in the radiative transfer equation is treated by means of the α-approximation. The Fleck–Cummings test problem is used to demonstrate performance of the multilevel QD method and study its iterative stability.
DA - 2019/1/1/
PY - 2019/1/1/
DO - 10.1016/j.jcp.2018.09.034
VL - 376
SP - 186-209
SN - 1090-2716
KW - Radiative transfer
KW - Numerical methods
KW - Quasidiffusion method
KW - Variable Eddington factor
KW - Multilevel iteration methods
KW - Fourier analysis
ER -
TY - JOUR
TI - Cold atmospheric plasma (CAP) differently affects migration and differentiation of keratinocytes via hydrogen peroxide and nitric oxide-related products
AU - Balzer, Julian
AU - Demir, Erhan
AU - Kogelheide, Friederike
AU - Fuchs, Paul C.
AU - Stapelmann, Katharina
AU - Oplaender, Christian
T2 - CLINICAL PLASMA MEDICINE
AB - A promising approach to treat infected chronic wounds is the treatment with “cold” atmospheric plasma (CAP) that has a broad antibacterial spectrum and can enhance microcirculation. Dielectric barrier discharge (DBD) devices generate CAP containing reactive species, leading to acidification and the accumulation of hydrogen peroxide (H2O2), nitrite and nitrate within the treated tissue/liquids. Since CAP produced species may affect wound healing and cell behavior, we investigated the possible DBD/CAP-induced effects on human keratinocytes. Primary keratinocytes were treated by a DBD device (13.5 kV, 300 Hz; 0–300 s). DBD-induced changes (pH; nitrite, nitrate; H2O2) in treated media were evaluated. As control and to investigate the impact of the CAP-produced species, equivalents amounts of H2O2, HCL, nitrite and nitrate as obtained by CAP treatments (0, 60, 300 s) were added separately or combined to keratinocytes. Cell viability and proliferation were determined by live cell imaging and a resazurin-based assay. Gap closure rates were assessed by migration assays. Differentiation/proliferation states were determined by qRT-PCR analysis of KI67 and involucrin. We found that even longer CAP-treatment times (300 s) did not reduce cell viability. However, migration/proliferation was affected by longer treatments resulting in a delay of gap closure in migration assays. The mRNA expression of involucrin and KI67 showed a pro-differentiation effect induced by longer CAP treatment. Similar effects could be induced by adding H2O2 in amounts found after a 300 s CAP treatment. The effects were reversed by catalase. Shorter CAP treatment (60 s) did not reveal pro-differentiation effects, but significantly accelerated gap closure. Lower H2O2 concentrations, equivalent to a 60 s CAP treatment, induced also upregulation of involucrin, which in turn could be diminished by low concentrations of nitrite/nitrate, indicating a potential mediation of H2O2-induced effects by parallel CAP-induced accumulation of these nitric oxide derivatives. CAP treatment theoretically could kill several birds with one stone—overcome bacterial contamination, improve microcirculation and additionally compensate missing H2O2 and nitric oxide— facilitating wound healing. However, clinical CAP treatment must be well balanced to avoid possible unwanted side effects, such as a delayed healing process and tissue damage.
DA - 2019/3//
PY - 2019/3//
DO - 10.1016/j.cpme.2018.11.001
VL - 13
SP - 1-8
SN - 2212-8166
UR - https://doi.org/10.1016/j.cpme.2018.11.001
KW - Cold atmospheric plasma
KW - Hydrogen peroxide, nitric oxide
KW - Nitrogen dioxide
KW - Nitric oxide delivery
KW - Topical application
ER -