TY - JOUR TI - Laser Powder Bed Fusion Additive Manufacturing of Oxide Dispersion Strengthened Steel Using Gas Atomized Reaction Synthesis Powder AU - Horn, T. AU - Rock, C. AU - Kaoumi, D. AU - Anderson, I. AU - White, E. AU - Prost, T. AU - Rieken, J. AU - Saptarshi, S. AU - Schoell, R. AU - DeJong, M. AU - Timmins, S. AU - Forrester, J. AU - Lapidus, S. AU - Napolitano, R. AU - Zhang, D. AU - Darsell, J. T2 - SSRN DA - 2022/// PY - 2022/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85127703398&partnerID=MN8TOARS ER - TY - JOUR TI - Spark Plasma Sintered Monbti Based Multi Principal Element Alloys with Cr, V, and Zr AU - Beausoleil, G.L. AU - Parry, M.E. AU - Mondal, K. AU - Gomez-Hurtado, L.R. AU - Aguiar, J.A. AU - Kaoumi, D. AU - Kwon, S. T2 - SSRN DA - 2022/// PY - 2022/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85130733691&partnerID=MN8TOARS ER - TY - RPRT TI - Implementation and testing of physics-based pulverization model in BISON AU - Aagesen, Larry, Jr. AU - Biswas, Sudipta AU - Gamble, Kyle AU - Jiang, Wen AU - Simon, Pierre-Clément AU - Spencer, Benjamin DA - 2022/6/30/ PY - 2022/6/30/ DO - 10.2172/1984930 UR - https://doi.org/10.2172/1984930 ER - TY - JOUR TI - Experimentally validated multiphysics modeling of fracture induced by thermal shocks in sintered UO2 pellets AU - McClenny, Levi D. AU - Butt, Moiz I. AU - Abdoelatef, M. Gomaa AU - Pate, Michal J. AU - Yee, Kay L. AU - Harikrishnan, R. AU - Perez-Nunez, Delia AU - Jiang, W. AU - Ortega, Luis H. AU - McDeavitt, Sean M. AU - Ahmed, Karim T2 - Journal of Nuclear Materials AB - Commercial nuclear power plants extensively rely on fission energy from uranium dioxide (UO2) fuel pellets that provide thermal energy; consequently, generating carbon-free power in current generation reactors. UO2 fuel incurs damage and fractures during operation due to large thermal gradients that develop across the fuel pellet during normal operation. The underlying mechanisms by which these processes take place are still poorly understood. This work is a part of our combined experimental and computational effort for quantifying the UO2 fuel fracture behavior induced by thermal shock. In this work, we describe an experimental study performed to understand the fuel fracturing behavior of sintered powder UO2 pellets when exposed to thermal shock conditions, as well as a multiphysics phase-field fracture model which accurately predicts the experimental results. Parametric studies and sensitivity analysis are used to assess uncertainty. Experimental data was collected from multiple experiments by exposing UO2 pellets to high-temperature conditions (900-1200C), which are subsequently quenched in sub-zero water. We exhibit that the fracture results gathered in the experimental setting can be consistently recreated by this work phase-field fracture model, demonstrating a reliable ability to our model in simulating the thermal shock gradients and subsequent fracture mechanics in the primary fuel source for Light-Water Reactors (LWRs). This model advanced the fundamental understanding of thermal shock and property correlations to advance utilization of UO2 as a fuel for nuclear reactors. DA - 2022/7// PY - 2022/7// DO - 10.1016/j.jnucmat.2022.153719 UR - https://doi.org/10.1016/j.jnucmat.2022.153719 ER - TY - RPRT TI - Assessment and Improvement of Fission Product Transport Predictions of Particle Fuel in BISON AU - Toptan, Aysenur AU - Jiang, Wen AU - Singh, Gyanender AU - Dhulipala, Som AU - Che, Yifeng AU - Hales, Jason AU - Novascone, Stephen AB - The U.S. Department of Energy’s Nuclear Energy Advanced Modeling and Simulation (NEAMS) program aims to develop predictive capabilities by applying computational methods to the analysis and design of advanced reactor and fuel cycle systems. This program has been providing engineering-scale support for the development of BISON, a high-fidelity and high-resolution fuel performance tool. This study was motivated by the need to incorporate more physics-based models in BISON in order to foster tri-structural isotropic (TRISO) applications. This document details the integration of new modeling capabilities in BISON, including (1) development of pyrolytic carbon (PyC) and silicon carbide (SiC) layer anisotropic thermal and mass transport capabilities, (2) verification of the mass diffusion solution in TRISO modeling, (3) calibration of fission product diffusivity using Advanced Gas Reactor (AGR) experiments, (4) improved fission product release modeling by developing compact diffusion modeling capabilities, and (5) documentation of accelerated failure analysis on the BISON website. Improvements made to the diffusion models and parameters were documented and validated against AGR-1 and -2 experiment data. DA - 2022/9/1/ PY - 2022/9/1/ DO - 10.2172/1901807 UR - https://doi.org/10.2172/1901807 ER - TY - JOUR TI - A phase-field model of quasi-brittle fracture for pressurized cracks: Application to UO2 high-burnup microstructure fragmentation AU - Jiang, Wen AU - Hu, Tianchen AU - Aagesen, Larry K. AU - Biswas, Sudipta AU - Gamble, Kyle A. T2 - Theoretical and Applied Fracture Mechanics AB - In this paper, we present a phase-field model of quasi-brittle fracture with pressurized cracks, with dedicated applications for polycrystalline materials. The model is formulated as a minimization problem within the variational framework. The external work done by pressure on the crack surfaces is included in the objective function. Several careful modeling choices lead to a regularization-length-independent critical strength. The model is constructed to give a softening response with an underlying linear traction-separation law. The pressure-dependent softening response and the regularization of the prescribed pressure are demonstrated with a (quasi) one-dimensional numerical analysis. In a two-dimensional numerical analysis under plane strain assumptions, the critical stress corresponding to crack propagation (as predicted by our quasi-brittle fracture model) is compared with linear elastic fracture mechanics (LEFM) analytical solutions. Our model is further utilized to simulate fission-gas-induced fragmentation of the UO2 high-burnup structure (HBS). Simulation results show that pressurized bubbles can cause crack nucleation and propagation, and that the bubble size and the surrounding external pressure affect the critical pressure corresponding to crack nucleation. Simulations of a partial HBS at different recrystallization stages show that different grain structures (due to recrystallization) also influence crack paths and fragmentation morphology. DA - 2022/6// PY - 2022/6// DO - 10.1016/j.tafmec.2022.103348 UR - https://doi.org/10.1016/j.tafmec.2022.103348 ER - TY - JOUR TI - Reliability estimation of an advanced nuclear fuel using coupled active learning, multifidelity modeling, and subset simulation AU - Dhulipala, Somayajulu L.N. AU - Shields, Michael D. AU - Chakroborty, Promit AU - Jiang, Wen AU - Spencer, Benjamin W. AU - Hales, Jason D. AU - Labouré, Vincent M. AU - Prince, Zachary M. AU - Bolisetti, Chandrakanth AU - Che, Yifeng T2 - Reliability Engineering & System Safety AB - Tristructural isotropic (TRISO)-coated particle fuel is a robust nuclear fuel and determining its reliability is critical for the success of advanced nuclear technologies. However, TRISO failure probabilities are small and the associated computational models are expensive. We used coupled active learning, multifidelity modeling, and subset simulation to estimate the failure probabilities of TRISO fuels using several 1D and 2D models. With multifidelity modeling, we replaced expensive high-fidelity (HF) model evaluations with information fusion from two low-fidelity (LF) models. For the 1D TRISO models, we considered three multifidelity modeling strategies: only Kriging, Kriging LF prediction plus Kriging correction, and deep neural network (DNN) LF prediction plus Kriging correction. While the results across these multifidelity modeling strategies compared satisfactorily, strategies employing information fusion from two LF models called the HF model least often. Next, for the 2D TRISO model, we considered two multifidelity modeling strategies: DNN LF prediction plus Kriging correction (data-driven) and 1D TRISO LF prediction plus Kriging correction (physics-based). The physics-based strategy, as expected, consistently required the fewest calls to the HF model. However, the data-driven strategy had a lower overall simulation time since the DNN predictions are instantaneous, and the 1D TRISO model requires a non-negligible simulation time. DA - 2022/10// PY - 2022/10// DO - 10.1016/j.ress.2022.108693 UR - https://doi.org/10.1016/j.ress.2022.108693 ER - TY - JOUR TI - Mechanistic calculation of the effective silver diffusion coefficient in polycrystalline silicon carbide: Application to silver release in AGR-1 TRISO particles AU - Simon, P.-C.A. AU - Aagesen, Larry K. AU - Jiang, Chao AU - Jiang, Wen AU - Ke, Jia-Hong T2 - Journal of Nuclear Materials AB - The silicon carbide (SiC) layer in tristructural isotropic (TRISO) fuel particles serves as a barrier to prevent the escape of fission products produced and not retained in the fuel kernel. The release of silver (Ag) is a concern due to the long half-life of the 110mAg isotope. However, accurately determining the fission gas release rate requires knowing the diffusion coefficient through the SiC layer. In this study, we leverage atomistic calculations of Ag diffusivity in SiC bulk and grain boundaries (GBs) to develop a mesoscale effective Ag diffusion coefficient (Deff) in SiC. Since GBs serve as pathways for Ag diffusion, Deff is defined as a function of temperature and microstructure variables. In particular, the size of SiC grains in the direction perpendicular to diffusion is shown to significantly affect Ag diffusion. The prediction of the mechanistic, mesoscale approach falls within one order of magnitude of empirical values. The temperature and microstructure-dependent effective Ag diffusivity in SiC is implemented in the fuel performance code Bison with a correction factor to predict Ag release from AGR-1 TRISO fuel particles. We hereby quantify the impact of SiC grain size on Ag release and improve Bison’s predictions. DA - 2022/5// PY - 2022/5// DO - 10.1016/j.jnucmat.2022.153669 VL - 563 SP - 153669 UR - https://doi.org/10.1016/j.jnucmat.2022.153669 ER - TY - JOUR TI - Efficient high-fidelity TRISO statistical failure analysis using Bison: Applications to AGR-2 irradiation testing AU - Jiang, Wen AU - Singh, Gyanender AU - Hales, Jason D. AU - Toptan, Aysenur AU - Spencer, Benjamin W. AU - Novascone, Stephen R. AU - Dhulipala, Somayajulu L.N. AU - Prince, Zachary M. T2 - Journal of Nuclear Materials AB - The ability of tri-structural isotropic (TRISO) fuel to contain fission products is largely dictated by the quality of the manufacturing process, since most of the fission product release is expected to occur due to coating layer failure in a small number of particles containing defects. The Bison fuel performance code has capabilities to predict failure in individual particles, accounting for the presence of defects, and to apply statistical analysis methods to compute the probability of failure in a set of fuel particles. Bison has recently undergone significant development both to improve its physical representations of fuel particle behavior and to improve the efficiency of its statistical failure calculations. Physical model improvements include new capabilities to account for the pressure generated by fission gases on inner pyrolytic carbon (IPyC) crack surfaces and to use local material coordinate orientation to accurately incorporate the anisotropy in the material properties in aspherical particles. To improve statistical modeling efficency, a direct integration approach which involves directly integrating the failure probability function associated with statistically varying parameters has been developed. The direct integration approach is much more efficient than the Monte Carlo (MC) schemes commenly employed, and allows Bison to directly run high-dimensional fuel performance models, which improves the accuracy of failure probability calculations. A set of benchmark problems is considered here to compare the MC and direct integration approaches, and a statistical failure analysis of compacts in the Advanced Gas Reactor (AGR)-2 experiments is performed using the direct integration approach. DA - 2022/4// PY - 2022/4// DO - 10.1016/j.jnucmat.2022.153585 VL - 562 SP - 153585 UR - https://doi.org/10.1016/j.jnucmat.2022.153585 ER - TY - JOUR TI - Accelerated statistical failure analysis of multifidelity TRISO fuel models AU - Dhulipala, Somayajulu L.N. AU - Jiang, Wen AU - Spencer, Benjamin W. AU - Hales, Jason D. AU - Shields, Michael D. AU - Slaughter, Andrew E. AU - Prince, Zachary M. AU - Labouré, Vincent M. AU - Bolisetti, Chandrakanth AU - Chakroborty, Promit T2 - Journal of Nuclear Materials AB - Statistical nuclear fuel failure analysis is critical for the design and development of advanced reactor technologies. Although Monte Carlo Sampling (MCS) is a standard method of statistical failure analysis for fuels, the low failure probabilities of some advanced fuel forms and the correspondingly large number of required model evaluations limit its application to low-fidelity (e.g., 1-D) fuel models. In this paper, we present four other statistical methods for fuel failure analysis in Bison, considering tri-structural isotropic (TRISO)-coated particle fuel as a case study. The statistical methods considered are Latin hypercube sampling (LHS), adaptive importance sampling (AIS), subset simulation (SS), and the Weibull theory. Using these methods, we analyzed both 1-D and 2-D representations of TRISO models to compute failure probabilities and the distributions of fuel properties that result in failures. The results of these methods compare well across all TRISO models considered. Overall, SS and the Weibull theory were deemed the most efficient, and can be applied to both 1-D and 2-D TRISO models to compute failure probabilities. Moreover, since SS also characterizes the distribution of parameters that cause TRISO failures, and can consider failure modes not described by the Weibull criterion, it may be preferred over the other methods. Finally, a discussion on the efficacy of different statistical methods of assessing nuclear fuel safety is provided. DA - 2022/5// PY - 2022/5// DO - 10.1016/j.jnucmat.2022.153604 VL - 563 SP - 153604 UR - https://doi.org/10.1016/j.jnucmat.2022.153604 ER - TY - JOUR TI - Off-line vs. semi-implicit TH-TH coupling schemes: A BEPU comparison AU - Casamor, M. AU - Avramova, M. AU - Reventos, F. AU - Freixa, J. T2 - ANNALS OF NUCLEAR ENERGY AB - Several TH-TH code coupling methods are used in the nuclear industry to model the core thermal–hydraulic conditions and the system behaviour. In some cases, the boundary conditions obtained by system codes are applied to sub-channel codes by table (off-line coupling). Even though this approach is in general considered valid, some boundary parameters will present inconsistencies. Alternatively, system and sub-channel codes are coupled using different coupling methods (semi-implicit coupling). Recent studies have shown a strong influence of the boundary conditions uncertainty on the sub-channel code results. The present study aims to evaluate the differences produced by the coupling methods by performing a best-estimate plus uncertainties (BEPU) comparison to the following cases: a complete loss of forced flow and a pressurizer relief valve opening. Results show that BEPU analysis presents good agreement with some discrepancies that can be explained and correlated to the boundary conditions deviations between codes. DA - 2022/12// PY - 2022/12// DO - 10.1016/j.anucene.2022.109344 VL - 178 SP - SN - 1873-2100 KW - PWR KW - Coupling KW - BEPU KW - DNBR ER - TY - RPRT TI - Challenge Problem 1: Preliminary Model Development and Assessment of Flexible Heat Transfer Modeling Approaches AU - Wiser, Ralph; AU - Baglietto, Emilio; AU - Iskhakov, Arsen; AU - Dinh, Nam T.; AU - Tai, Cheng-Kai; AU - Bolotnov, Igor; AU - Nguyen, Tri; AU - Merzari, Elia; AU - Shaver, Dillon AB - plenum of Texas A&M University’s 1/16th scaled very-high-temperature gas-cooled reactor (VHTR), and (2) development of wall heat-transfer correlation for laminar flow in a wall-heated pipe. The CFD tool validation exercises can be helpful to choose the models and CFD tools to simulate and design specific components of the HTRGs such as upper plenum where jet mixing is a complex phenomenon. In a loss of forced circulation event, the laminar flow can be observed during the development of natural circulation flow. This work includes the development and validation of heat transfer correlations for laminar flow using the Nek5000 CFD code due to limited available experimental data for laminar flow conditions to guide low-order models (1D). In this report, the flow characteristics of a single isothermal jet discharging into the upper plenum was investigated using the Nek5000 Large-Eddy Simulation (LES) CFD tool. Several numerical simulations were performed for various jet-discharged Reynolds numbers ranging from 3,413 to 12,819. A grid-independent study was performed. The numerical results of mean velocity, root-mean-square fluctuating velocity, and Reynolds stress were compared against the benchmark data. Good agreement was obtained between simulated and measured data for axial mean velocities, except near the upper plenum hemisphere. The maximum predicted errors for axial mean velocities at various normalized coolant channel diameter heights of 1, 5, and 10 are 1.56%, 1.88%, and 3.82%, respectively. In addition, the predicted root-mean-square fluctuating velocity and Reynolds stress are qualitatively in agreement with the experimental data. The Nek5000 code was used to develop wall-heat transfer correlation for laminar flow in a cylindrical tube. Several simulations were performed for various Reynolds flow and wall-heat fluxes. A new heat transfer correlation was developed using data from Nek5000 simulation results and regression functions in Matlab. The developed heat transfer correlation is valid for various Reynolds flows from 200 to 2000. The predicted R² value for model fit was 0.875, which ensures that 87.5% of the model data lies on the Nek5000 data. Moreover, a machine learning (ML) tool was used to train and test the Nek5000 data. A good fit of the ML-based model was observed with the test data. DA - 2022/6// PY - 2022/6// DO - 10.2172/1881860 UR - https://www.osti.gov/biblio/1881860 ER - TY - CONF TI - Probabilistic Methods for Cyclical and Coupled Systems with Changing Failure Rates AU - Yang Hui Otani, Courtney Mariko ; AU - Christian, Robby ; AU - Prescott, Steven R ; AU - Diaconeasa, Mihai ; AU - Earthperson, Arjun C2 - 2022/4// DA - 2022/4// UR - https://www.osti.gov/biblio/1885929 ER - TY - JOUR TI - Harnessing the Environment to Identify Nuclear Processes: Biologically-Mediated Approaches AU - Meeks, H.N. AU - Steen, T. AU - McKendee, W.M. AU - Otis, R.P. AU - Cui, H.H. AU - Volpe, R. AU - Hayes, R.B. AU - Agans, R.T. AU - Lewis, A. T2 - Countering WMD Journal DA - 2022/// PY - 2022/// VL - 24 SP - 60–85 ER - TY - JOUR TI - Harnessing the Environment to Identify Nuclear Processes: I. Biological Markers to Assess Environmental Exposure AU - Meeks, H.N. AU - Oates, R.P. AU - Cui, H. AU - Hwang, G.M. AU - Volpe, R.P. AU - Hayes, R.B. AU - Steen, T.Y. AU - Agans, R.T. AU - Turick, C.E. AU - Brigmon, R. AU - Liebeskind, B. AU - Ganguly, K. AU - Sussman, M.R. AU - Lee, B.D. AU - Lewis, A. AU - Winder, E. AU - Schabacker, D. AU - McKendree, W.L. T2 - Countering WMD Journal DA - 2022/// PY - 2022/// VL - 24 SP - 93–119 ER - TY - JOUR TI - A Novel Approach for Detection of Illicit Nuclear Activities Using Optically Stimulated Dosimetry AU - Aras, E.M. AU - Hayes, R.B. T2 - ESARDA Bulletin - The International Journal of Nuclear Safeguards and Non-proliferation DA - 2022/6// PY - 2022/6// VL - 64 IS - 1 SP - 64–74 ER - TY - JOUR TI - A Standard Model Approach to Inflation AU - Hayes, Robert Bruce T2 - Journal of Modern Physics AB - By assuming the cosmological principle includes the Pauli Exclusion Principle (PEP) and that the initial singularity existed within Planck time and length scales, a model for inflationary expansion is argued using only standard model physics without any changes to general relativity. All Fermionic matter is forced by the PEP to make a quantum transition to minimally orthogonal states in sequential Planck time intervals. This results in an initial inflation effect due to nearest neighbor quantum transitions which is then exacerbated by matter and antimatter creation effects due to collisions giving rise to the observational effects of universal inflation. The model provides a mechanistic explanation for primordial expansion using only physics from the standard model, specifically utilizing the PEP as a repulsion force between indistinguishable fermions. The present theory offers the benefit of not requiring any particles or fields outside of the standard model nor utilizing changes to general relativity. More succinctly, this theory goes beyond simply offering a mathematical representation (or fit) of the functional dependence but rather offers a mechanistic model to drive inflation using only standard model physics. DA - 2022/// PY - 2022/// DO - 10.4236/jmp.2022.132009 VL - 13 IS - 02 SP - 113-121 J2 - JMP OP - SN - 2153-1196 2153-120X UR - http://dx.doi.org/10.4236/jmp.2022.132009 DB - Crossref ER - TY - JOUR TI - In situ TEM Observations of Thermally Activated Phenomena in Materials Under Far-From-Equilibrium Conditions AU - Vijayan, Sriram AU - Bawane, Kaustubh AU - Giulia Dilemma, Fidelma AU - He, Lingfeng AU - Fink, Carolin AU - Jinschek, Joerg R T2 - Microscopy and Microanalysis AB - Journal Article In situ TEM Observations of Thermally Activated Phenomena in Materials Under Far-From-Equilibrium Conditions Get access Sriram Vijayan, Sriram Vijayan Department of Materials Science & Engineering, The Ohio State University, Columbus, Ohio, USA Corresponding author: vijayan.13@osu.edu Search for other works by this author on: Oxford Academic Google Scholar Kaustubh Bawane, Kaustubh Bawane Idaho National Laboratory, Idaho Falls, Idaho, USA Search for other works by this author on: Oxford Academic Google Scholar Fidelma Giulia Dilemma, Fidelma Giulia Dilemma Idaho National Laboratory, Idaho Falls, Idaho, USA Search for other works by this author on: Oxford Academic Google Scholar Lingfeng He, Lingfeng He Idaho National Laboratory, Idaho Falls, Idaho, USA Search for other works by this author on: Oxford Academic Google Scholar Carolin Fink, Carolin Fink Department of Materials Science & Engineering, The Ohio State University, Columbus, Ohio, USA Search for other works by this author on: Oxford Academic Google Scholar Joerg R Jinschek Joerg R Jinschek National Center for Nano Fabrication and Characterization (DTU Nanolab), Technical University of Denmark (DTU), Kgs. Lyngby, Denmark Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Pages 1844–1846, https://doi.org/10.1017/S1431927622007255 Published: 01 August 2022 DA - 2022/8/1/ PY - 2022/8/1/ DO - 10.1017/S1431927622007255 VL - 28 IS - S1 SP - 1844-1846 LA - en OP - SN - 1435-8115 1431-9276 UR - http://dx.doi.org/10.1017/S1431927622007255 DB - Crossref ER - TY - JOUR TI - Real-time, On-Microscope Automated Quantification of Features in Microcopy Experiments Using Machine Learning and Edge Computing AU - Field, Kevin G AU - Patki, Priyam AU - Sharaf, Nasir AU - Sun, Kai AU - Hawkins, Laura AU - Lynch, Matthew AU - Jacobs, Ryan AU - Morgan, Dane D AU - He, Lingfeng AU - Field, Christopher R T2 - Microscopy and Microanalysis AB - Journal Article Real-time, On-Microscope Automated Quantification of Features in Microcopy Experiments Using Machine Learning and Edge Computing Get access Kevin G Field, Kevin G Field University of Michigan – Ann Arbor, Ann Arbor, MI, United StatesTheia Scientific, LLC, Arlington, VA, United States Corresponding author: kgfield@umich.edu Search for other works by this author on: Oxford Academic Google Scholar Priyam Patki, Priyam Patki University of Michigan – Ann Arbor, Ann Arbor, MI, United States Search for other works by this author on: Oxford Academic Google Scholar Nasir Sharaf, Nasir Sharaf Theia Scientific, LLC, Arlington, VA, United States Search for other works by this author on: Oxford Academic Google Scholar Kai Sun, Kai Sun University of Michigan – Ann Arbor, Ann Arbor, MI, United States Search for other works by this author on: Oxford Academic Google Scholar Laura Hawkins, Laura Hawkins Texas A&M University, College Station, TX, United States Search for other works by this author on: Oxford Academic Google Scholar Matthew Lynch, Matthew Lynch University of Michigan – Ann Arbor, Ann Arbor, MI, United States Search for other works by this author on: Oxford Academic Google Scholar Ryan Jacobs, Ryan Jacobs University of Wisconsin – Madison, Madison, WI, United States Search for other works by this author on: Oxford Academic Google Scholar Dane D Morgan, Dane D Morgan University of Wisconsin – Madison, Madison, WI, United States Search for other works by this author on: Oxford Academic Google Scholar Lingfeng He, Lingfeng He Texas A&M University, College Station, TX, United StatesIdaho National Laboratory, Idaho Falls, ID, United States Search for other works by this author on: Oxford Academic Google Scholar Christopher R Field Christopher R Field Theia Scientific, LLC, Arlington, VA, United States Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Pages 2046–2048, https://doi.org/10.1017/S1431927622007929 Published: 01 August 2022 DA - 2022/8/1/ PY - 2022/8/1/ DO - 10.1017/S1431927622007929 VL - 28 IS - S1 SP - 2046-2048 LA - en OP - SN - 1435-8115 1431-9276 UR - http://dx.doi.org/10.1017/S1431927622007929 DB - Crossref ER - TY - JOUR TI - Measurement of grain boundary strength of Inconel X-750 superalloy using in-situ micro-tensile testing techniques in FIB/SEM system AU - Wang, Yachun AU - Liu, Xiang AU - Murray, Daniel J. AU - Teng, Fei AU - Jiang, Wen AU - Bachhav, Mukesh AU - Hawkins, Laura AU - Perez, Emmanuel AU - Sun, Cheng AU - Bai, Xianming AU - Lian, Jie AU - Judge, Colin D. AU - Jackson, John H. AU - Carter, Robert G. AU - He, Lingfeng T2 - Materials Science and Engineering: A AB - Grain boundaries (GBs), known as two-dimensional defects, are omnipresent in polycrystalline metallic alloys and thus influence a wide range of mechanical properties under different environmental conditions like irradiation and corrosion. Therefore, quantifying the strength of individual GBs is critical for understanding the degradation of mechanical properties of materials under different conditions. In this study we developed an efficient approach for the fabrication of micro-tensile specimens with a GB almost perpendicular to the tensile direction, which is expected to advance the development of individual GB tensile testing at micro or nanoscale in a wide scope of materials. An in-situ cantilever micro-tensile testing method was developed and used to quantify the strength of a ∑3 GB in Inconel X-750 with the combination of finite element modeling. The average ultimate tensile strength (UTS) of a non-irradiated ∑3 GB is estimated at around 1.4 GPa, comparable to that of a neutron-irradiated ∑3 GB with a dose of ∼1.5 dpa (1.3 GPa). Moreover, the in-situ push-to-pull micro-tensile testing technique developed in this work provides valuable insights into the high-angle GB deformation and fracture behavior. This method generates qualitatively similar ductility behavior before and after neutron irradiation as the bulk material testing. However, the ductility and UTS values obtained from this method are different from bulk measurements due to vastly different specimen dimensions. DA - 2022/8// PY - 2022/8// DO - 10.1016/j.msea.2022.143475 VL - 849 SP - 143475 J2 - Materials Science and Engineering: A LA - en OP - SN - 0921-5093 UR - http://dx.doi.org/10.1016/j.msea.2022.143475 DB - Crossref ER - TY - JOUR TI - Phase stability, mechanical properties, and ion irradiation effects in face-centered cubic CrFeMnNi compositionally complex solid-solution alloys at high temperatures AU - Parkin, Calvin AU - Moorehead, Michael AU - Elbakhshwan, Mohamed AU - Zhang, Xuan AU - Xiu, Pengyuan AU - He, Lingfeng AU - Bachhav, Mukesh AU - Sridharan, Kumar AU - Couet, Adrien T2 - Journal of Nuclear Materials AB - Two CrFeMnNi face-centered cubic complex concentrated solid-solution alloys (CSA) have been evaluated for phase stability, mechanical properties, and radiation damage effects from heavy ions. Cr18Fe27Mn27Ni28 and Cr15Fe35Mn15Ni35 were predicted by thermodynamic calculations to phase separate and maintain a single phase at 700 °C, respectively. Aging experiments at this temperature confirmed varying degrees of precipitation of a body-centered cubic phase in both Cr18Fe27Mn27Ni28 and Cr15Fe35Mn15Ni35. The alloys showed promising strength in tensile deformation at room temperature, with yield strengths of 155 MPa and 151 MPa for Cr18Fe27Mn27Ni28 and Cr15Fe35Mn15Ni35, respectively. At 500 °C, the yield strength of Cr18Fe27Mn27Ni28 fell to 93 MPa, and to 100 MPa in Cr15Fe35Mn15Ni35. Unlike Cr18Fe27Mn27Ni28, Cr15Fe35Mn15Ni35 gained some ductility at 500 °C compared to room temperature. The two CSAs were irradiated to 75 dpa at 500 °C in the plateau region of the displacement curve using 3.7 MeV Ni2+ ions, alongside model alloy 709 as a reference. Irradiation results produced similar densities and sizes of dislocations loops in the two CSAs compared to the reference. However, while large voids form in the plateau region of Cr18Fe27Mn27Ni28, small voids form just beyond the displacement peak of Cr15Fe35Mn15Ni35. Atom probe tomography and energy dispersive X-ray spectroscopy-equipped scanning transmission electron microscopes were used to characterize the alloys for changes in chemical distribution. DA - 2022/7// PY - 2022/7// DO - 10.1016/j.jnucmat.2022.153733 VL - 565 SP - 153733 J2 - Journal of Nuclear Materials LA - en OP - SN - 0022-3115 UR - http://dx.doi.org/10.1016/j.jnucmat.2022.153733 DB - Crossref ER - TY - JOUR TI - Effect of dpa rate on the temperature regime of void swelling in ion-irradiated pure chromium AU - Gabriel, Adam AU - Hawkins, Laura AU - French, Aaron AU - Li, Yongchang AU - Hu, Zhihan AU - He, Lingfeng AU - Xiu, Pengyuan AU - Nastasi, Michael AU - Garner, Frank.A. AU - Shao, Lin T2 - Journal of Nuclear Materials AB - Pure chromium is a promising candidate for coating of Zircalloy fuel rods in light water-cooled power reactors to avoid or delay hydrogen generation in accident scenarios. Void swelling of chromium is one possible contributor to coating-interface failure and needs to be studied. The effect of dpa rate on void swelling of Cr was studied using 5 MeV Fe ion irradiation to 15 peak dpa at peak dpa rates of 3.5 × 10−5, 3.5 × 10−4, and 3.5 × 10−3 dpa/s, at six temperatures between 350 °C and 650 °C. The post-transient (steady-state) swelling rate of pure Cr is ∼0.05%/dpa. Swelling in Cr also appeared to start at a much higher swelling rate at very low doses. The observed dependence of peak swelling temperature on dpa rate agrees well with earlier theoretical models and clearly demonstrated the well-known “temperature shift” phenomenon. After determination of the peak swelling temperatures under ion irradiation at three dpa rates we extrapolated downwards to dpa rates characteristic of both sodium-cooled fast reactors and light water-cooled reactors. DA - 2022/4// PY - 2022/4// DO - 10.1016/j.jnucmat.2022.153519 VL - 561 SP - 153519 J2 - Journal of Nuclear Materials LA - en OP - SN - 0022-3115 UR - http://dx.doi.org/10.1016/j.jnucmat.2022.153519 DB - Crossref ER - TY - JOUR TI - Electrochemical noise studies on localized corrosion of Ni and Ni-20Cr in molten ZnCl2 AU - Sure, Jagadeesh AU - Gill, Simerjeet k AU - Wang, Yachun AU - Bawane, Kaustubh.K. AU - He, Lingfeng AU - Halstenberg, Phillip AU - Dai, Sheng AU - Mahurin, Shannon M. AU - Wishart, James F. AU - Sasaki, Kotaro T2 - Electrochimica Acta AB - The electrochemical noise (ECN) technique was employed to study corrosion of two model systems, i.e. pure Ni and a binary Ni-20 wt%Cr (Ni20Cr) alloy in molten ZnCl2 at 623 K. We measured ECN transients in current and open-circuit potential from two nominally identical Ni-Ni and Ni20Cr-Ni20Cr electrodes and one galvanic Ni-Ni20Cr electrode pair. The behavior of ECN is quite distinct among the three-electrode systems, and it is correlated with the various microscopic observations of micro- and nano-scale morphological features. Based on the ECN study coupled with the microstructural analysis, the origins of ECN in the molten salt environment as well as the mechanisms of localized corrosion in the three systems are discussed. DA - 2022/11// PY - 2022/11// DO - 10.1016/j.electacta.2022.141126 VL - 431 SP - 141126 J2 - Electrochimica Acta LA - en OP - SN - 0013-4686 UR - http://dx.doi.org/10.1016/j.electacta.2022.141126 DB - Crossref ER - TY - JOUR TI - A combined theoretical-experimental investigation of thermal transport in low-dose irradiated thorium dioxide AU - Deskins, W. Ryan AU - Khanolkar, Amey AU - Mazumder, Sanjoy AU - Dennett, Cody A. AU - Bawane, Kaustubh AU - Hua, Zilong AU - Ferrigno, Joshua AU - He, Lingfeng AU - Mann, J. Matthew AU - Khafizov, Marat AU - Hurley, David H. AU - El-Azab, Anter T2 - Acta Materialia AB - During reactor operation, nuclear fuels are subject to extreme temperature and irradiation conditions which can significantly degrade the fuel's thermal transport properties. The reduction in thermal conductivity of the fuel as a result of irradiation-induced lattice defects is arguably the most important fuel performance metric in regard to reactor efficiency and safety. Because thorium dioxide (ThO2) is suitable as a model system for more complex materials such as UO2 and its mixed oxides, we present a theoretical investigation of thermal conductivity reduction seen in defect-bearing thorium dioxide and compare directly to experimental measurements. Phonon-mediated thermal transport of the fuel is modeled by a solution to the Boltzmann transport equation (BTE) for phonons. A cluster dynamics (CD) model for lattice defect evolution during irradiation predicts defect densities which are used as input to the BTE for modeling phonon-defect scatterings. Phonon scatterings by lattice defects include those from point defects and vacancy clusters and interstitial clusters of various sizes. The CD model is benchmarked against structural defect characterization of irradiated thorium dioxide using electron microscopy. Thermal conductivity predicted by the BTE model is compared to measured values for irradiated thorium dioxide specimens below room temperature to isolate effects of phonon-defect scattering from intrinsic 3-phonon processes, which dominate at higher temperatures. The computed conductivity values are in partial agreement at temperatures close to room temperature while slight deviations are observed at the lowest measured temperatures, suggesting that implemented phonon-defect scattering cross-section expressions may not be adequate for low temperatures. The presented work provides a necessary investigation of the influence of irradiation induced defects on fuel performance and represents a first step toward a full characterization of phonon mediated thermal transport in irradiated materials with complex defect microstructure. DA - 2022/12// PY - 2022/12// DO - 10.1016/j.actamat.2022.118379 VL - 241 SP - 118379 J2 - Acta Materialia LA - en OP - SN - 1359-6454 UR - http://dx.doi.org/10.1016/j.actamat.2022.118379 DB - Crossref ER - TY - JOUR TI - Assessing the interfacial corrosion mechanism of Inconel 617 in chloride molten salt corrosion using multi-modal advanced characterization techniques AU - Copeland-Johnson, Trishelle M. AU - Murray, Daniel J. AU - Cao, Guoping AU - He, Lingfeng T2 - Frontiers in Nuclear Engineering AB - The United States Department of Energy (DOE) has committed to expanding the domestic clean energy portfolio in response to the rising challenges of energy security in the wake of climate change. Accordingly, the construction of a series of Generation IV reactor technologies are being demonstrated, including sodium-cooled, small modular, and molten chloride fast reactors (MCFRs). To date, there are no fully qualified structural materials for constructing MCFRs. A number of commercial structural alloys have been considered for the construction of MCFRs, including alloys from the Inconel and Hastelloy series. Informed qualification of structural materials for the construction of MCFRs in the future can only be ensured by expanding the current fundamental knowledgebase of information pertaining to material performance under environmental stressors relevant to operation of the reactor, including corrosion susceptibility. The purpose of this investigation is to illustrate how a correlative multi-modal electron microscopy characterization approach, including the novel application of focused-ion beam 3D reconstruction capabilities, can elucidate the corrosion mechanism of a candidate structural material Inconel 617 for MCFR in NaCl-MgCl 2 eutectic salt at 700°C for 1,000 h. Evidence of intergranular corrosion, Ni and Fe dealloying, and Cr-O enrichment along the grain boundary, which most likely corresponds to Cr 2 O 3 , is a phenomenon that has been documented in other Ni-based superalloys exposed to chloride molten salt systems. Additional corrosion products, including the formation of insoluble MgAl 2 O 4 , within the porous network produced by the salt attack is a novel observation. In addition, Mo 3 Si 5 and τ 2 precipitates are detected in the alloy bulk and are dissolved by the salt. Furthermore, the lack of detection of design γ′ precipitates in Inconel 617 after 1,000 h could indicate that the molten salt corrosion mechanism has indirectly induced a phase transformation of Al 2 TiNi (τ 2 ) and Ni 3 (Al,Ti) (γ’) phase. This investigation provides a comprehensive understanding of molten salt corrosion mechanisms in a complex material system such as a commercial structural alloy for applications in MCFRs. DA - 2022/12/5/ PY - 2022/12/5/ DO - 10.3389/fnuen.2022.1049693 VL - 1 J2 - Front. Nucl. Eng. OP - SN - 2813-3412 UR - http://dx.doi.org/10.3389/fnuen.2022.1049693 DB - Crossref ER - TY - JOUR TI - Extending a low-order inhomogeneous adjoint equations model to a higher-order model with verification on integral applications AU - Altahhan, Muhammad Ramzy AU - Geemert, Rene AU - Avramova, Maria AU - Ivanov, Kostadin T2 - ANNALS OF NUCLEAR ENERGY AB - • Development and verification of a NEM-M2B2 mathematical inhomogeneous-adjoint nodal diffusion solver. • Application of the Lagrangian multipliers method to derive the nodal mathematical inhomogeneous-adjoint. • Derived the local linear prediction formula, specific for the forward NEM-M2B2 model, and utilized it to study the repercussions of perturbations in the IAEA-3D benchmark on the Axial Offset (AO). • Verified the generalized adjoint code developed while showing detailed steps of how inhomogeneous adjoint codes can be verified. • Compared between the low-order inhomogeneous NEM-M0 adjoint and the developed higher order inhomogeneous NEM-M2B2 model for the AO as a RoI. • Introduced the Mantissa theory to explain the behavior of the linear adjoint models and prediction formulas. A higher-order nodal mathematical inhomogeneous adjoint model conjugate to the NEM-M2B2 nodal diffusion forward model is developed and introduced in this research. Verification of the developed model is presented through applications in perturbation analysis and the IAEA-3D benchmark including adjusted forms of it. This paper’s objective is to explore ways of extending and optimizing a mathematical adjoint capability suitable for use in an industrial reactor code, such that it becomes not merely an approximate but rather the exact adjoint counterpart to the typically used higher-order nodal forward solvers used in mature industrial reactor codes. Specifically, it is investigated how to upgrade an already available lower-order nodal mathematical adjoint solver towards higher-order accuracy. An example of the latter is the lower-order nodal adjoint solver used in the ARTEMIS reactor code, in the technical context of stabilization and acceleration of embedded control rod search mechanisms. Though the latter adjoint solver proved suitable for the needed preconditioning purposes, while also enabling the benefit of computationally very lean adjoint iterations, several future developments could benefit from having a higher-order adjoint nodal solver available as well. By using a preconditioned form of the base NEM-M2B2 nodal diffusion forward model and by using variational analysis, we have obtained a higher-order nodal mathematical adjoint that can have a physical interpretation associated with it as a Lagrangian multiplier. The nodal mathematical adjoint is then developed for the Axial Offset (AO) as a Response of Interest (RoI) which leads to an inhomogeneous adjoint system of equations. A solution verification of the adjoint developed is done through analyzing the effects coming from perturbations in the absorption and the scattering cross-sections. The applications investigated include axially and radially traveling perturbations along the reactor’s core. Several locations for the traveling perturbations are chosen to represent important locations in the core. Comparison between the low-order and the higher-order adjoint models is conducted. The forward model is set to the NEM-M2B2 nodal diffusion equation for both adjoints during the comparison. The higher-order adjoint model developed show consistent results in comparison to its lower-order sibling, suggesting the preference of using the developed higher-order model for adjoint computations. DA - 2022/11// PY - 2022/11// DO - 10.1016/j.anucene.2022.109277 VL - 177 SP - SN - 1873-2100 KW - Nodal Expansion Method (NEM) KW - Adjoint Lagrange Multiplier KW - Axial Offset (AO) KW - Perturbation analysis KW - Sensitivity analysis KW - IAEA ER - TY - CONF TI - LMFR design and optimization methodology AU - Al-Dawood, Khaldoon A.; AU - Palmtag, Scott P. C2 - 2022/7// DA - 2022/7// UR - https://www.osti.gov/biblio/23178727 ER - TY - CONF TI - Control rod modeling in liquid metal-cooled fast reactors AU - Kiefer, T. M.; AU - Dawn, W. C.; AU - Al-Dawood, K.; AU - Palmtag, S. C2 - 2022/7// DA - 2022/7// UR - https://www.osti.gov/biblio/23178744 ER - TY - CONF TI - VERA BWR Progression Problems AU - Lawing, Chase ; AU - Palmtag, Scott ; AU - Asgari, Mehdi C2 - 2022/5// DA - 2022/5// UR - https://www.osti.gov/biblio/1890346 ER - TY - JOUR TI - Laser powder bed fusion additive manufacturing of oxide dispersion strengthened steel using gas atomized reaction synthesis powder AU - Horn, Timothy AU - Rock, Christopher AU - Kaoumi, Djamel AU - Anderson, Iver AU - White, Emma AU - Prost, Tim AU - Rieken, Joel AU - Saptarshi, Sourabh AU - Schoell, Ryan AU - DeJong, Matt AU - Timmins, Sarah AU - Forrester, Jennifer AU - Lapidus, Saul AU - Napolitano, Ralph AU - Zhang, Dalong AU - Darsell, Jens T2 - MATERIALS & DESIGN AB - Mechanically alloyed Fe-based alloys with oxide dispersion strengthening have largely dropped out of the marketplace due to high cost related to problems with complex and unreliable processing. Nevertheless, the desirable properties of oxide dispersion strengthened (ODS) steels have motivated research on alternate processing routes aimed at improving processing simplicity and reliability. Powders produced by gas atomization reaction synthesis (GARS) consist of stable Fe-Y intermetallic phases and a Cr surface oxide layer that acts as a chemical reservoir during solid-state processing and heat treatment to form a high density of nano-scale oxides. This research explores the use of Fe GARS powders, with 15 wt% Cr with micro-alloyed additions of 0.15 wt% Y and 0.10% Ti, in laser powder bed fusion (LPBF) additive manufacturing (AM), and evaluates the effectiveness of oxide dispersoid formation in the liquid melt pool. Additional oxygen was introduced by varying the LPBF chamber atmospheres using Ar, Ar + 1 wt% O, Ar + 5 wt% O, and air. Characterization of LPBF consolidated solids demonstrated the formation of a high density of nano-scale Y-Ti oxides in the build microstructures from the GARS precursor powders. DA - 2022/4// PY - 2022/4// DO - 10.1016/j.matdes.2022.110574 VL - 216 SP - SN - 1873-4197 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85127141491&partnerID=MN8TOARS ER - TY - JOUR TI - Growing solid deuterium for UCN production AU - Korobkina, Ekaterina AU - Berkutov, Igor AU - Golub, Robert AU - Huffman, Paul AU - Hickman, Clark AU - Leung, Kent AU - Medlin, Graham AU - Morano, Matthew J. AU - Rao, Thomas AU - Teander, Cole AU - White, Christian AU - Young, Albert R. T2 - JOURNAL OF NEUTRON RESEARCH AB - We have experimentally studied growing a large (about 1 liter) ortho-deuterium crystal in a real UCN source cryostat and recorded the growing process optically using a camera. The best quality was observed when growing the crystal directly from a vapor phase. The crystal was grown at different mass flows of deuterium and annealed at different temperatures. Optimum conditions were found for both, obtaining an optically transparent crystal and cooling it down with minimal damage. We found that the quality, final shape and changes during annealing of the crystal are very much dependent on the temperature profile of the cryostat walls. DA - 2022/// PY - 2022/// DO - 10.3233/JNR-220010 VL - 24 IS - 2 SP - 179-191 SN - 1477-2655 KW - Solid deuterium KW - ultra-cold neutrons ER - TY - JOUR TI - Chemistry Dependence of Corrosion Mechanisms in Model Binary Metallic Glasses and Correlation with Electron Work Function AU - Mahajan, Chaitanya AU - Hasannaeimi, Vahid AU - Pole, Mayur AU - Kautz, Elizabeth J. AU - Gwalani, Bharat AU - Mukherjee, Sundeep T2 - SSRN Electronic Journal AB - Effect of chemistry change on corrosion mechanisms and passive film characteristics of model binary metallic glasses was studied. The corrosion current density decreased, and the corrosion potential increased towards nobler values with increase in phosphorus content for both Ni100-xPx and Co100-xPx amorphous systems (x = 10, 15, and 20 at. %). Scanning kelvin probe analysis showed an increase in volta potential for both the alloy systems with increase in phosphorus content. Enrichment of phosphorus in the passive layer was observed by advanced microscopy, which likely promoted the restoration of protective hypophosphite anion layer for the alloys with higher phosphorus content. DA - 2022/// PY - 2022/// DO - 10.2139/ssrn.4011828 J2 - SSRN Journal LA - en OP - SN - 1556-5068 UR - http://dx.doi.org/10.2139/ssrn.4011828 DB - Crossref ER - TY - JOUR TI - Revealing the complexity of high temperature oxide formation in a 38Ni-21Cr-20Fe-13Ru-6Mo-2W (at. %) multi-principal element alloy AU - Schreiber, Daniel K. AU - Kautz, Elizabeth J. AU - Olszta, Matthew J. AU - Kruska, Karen AU - Gerard, Angela Y. AU - Quiambao-Tomko, Kathleen F. AU - Scully, John R. T2 - Scripta Materialia AB - The oxide film formed on a corrosion-resistant multi-principal element alloy 38Ni-21Cr-20Fe-13Ru-6Mo-2W (at. %) was characterized via transmission electron microscopy and atom probe tomography. Oxidation in air at 600°C for 1080 minutes resulted in a complex, layered film with multiphase inner and outer oxide scales, and localized recrystallization in the underlying base alloy. The outer oxide scale is dominated by two phases: a Ni-Fe spinel (≈NiFe2O4) and a Ni-rich monoclinic phase (NiMoO4). The inner oxide consists of a near surface Ni-Fe-Cr spinel and RuO2, and semi-continuous Cr2O3 with oxygen-rich Ru-Mo metal inclusions. Local recrystallization and concomitant elemental partitioning in the base alloy was influenced by a high dislocation density in the as-prepared sample surface. DA - 2022/3// PY - 2022/3// DO - 10.1016/j.scriptamat.2021.114419 VL - 210 SP - 114419 J2 - Scripta Materialia LA - en OP - SN - 1359-6462 UR - http://dx.doi.org/10.1016/j.scriptamat.2021.114419 DB - Crossref KW - Oxidation corrosion KW - Three-dimensional atom probe (3DAP) KW - Scanning/transmission electron microscopy (STEM) ER - TY - JOUR TI - Compositional partitioning during early stages of oxidation of a uranium-molybdenum alloy AU - Kautz, Elizabeth J. AU - Lambeets, Sten V. AU - Royer, Jacqueline AU - Perea, Daniel E. AU - Harilal, Sivanandan S. AU - Devaraj, Arun T2 - Scripta Materialia AB - Compositional partitioning during uranium alloy oxidation was studied via complementary ex situ - in situ atom probe tomography. Nanoscopic volumes of uranium- 22 at. % molybdenum were exposed to air at room temperature/atmospheric pressure for 30–60 minutes (ex situ), and 300 ∘C - 10−5 mbar O2 gas for 2–5 minutes in a chemical reaction chamber attached to an atom probe system (in situ). For all environmental conditions, a hypostoichiometric uranium oxide is formed. Reaction fronts are observed at oxide/metal, oxide/hydride, and outer oxide/environment interfaces. Results reveal Mo redistributes across the oxide/metal interface, with a tendency for enrichment in the outer oxide. The formation of a hydrogen-rich subsurface layer between the oxide and base alloy accompanies oxidation in both air and oxygen gas environments. Carbon and silicon impurity elements also redistribute to the outer oxide, contributing to oxide film composition. DA - 2022/4// PY - 2022/4// DO - 10.1016/j.scriptamat.2022.114528 VL - 212 SP - 114528 J2 - Scripta Materialia LA - en OP - SN - 1359-6462 UR - http://dx.doi.org/10.1016/j.scriptamat.2022.114528 DB - Crossref KW - Oxidation KW - Uranium KW - U-Mo KW - Atom probe tomography KW - Corrosion ER - TY - ER - TY - ER - TY - ER - TY - ER - TY - JOUR TI - Corrosion mechanisms in model binary metallic glass coatings on mild steel and correlation with electron work function AU - Mahajan, Chaitanya AU - Hasannaeimi, Vahid AU - Pole, Mayur AU - Kautz, Elizabeth AU - Gwalani, Bharat AU - Mukherjee, Sundeep T2 - Corrosion Science AB - Effect of chemistry change on corrosion mechanisms and passive film characteristics of model Ni-P and Co-P metallic glass coatings on mild steel was studied because of their simple chemistry and widespread use. Increase in phosphorus content led to improved corrosion resistance. Results indicated the presence of hypophosphite and phosphate anions on the corroded surfaces. Enrichment of phosphorus in the passive layer was observed, which likely promoted the restoration of the protective hypophosphite anion layer during dissolution. A correlation between electronic structure and corrosion resistance was established, with relative work function increasing with increase in phosphorus content. DA - 2022/10// PY - 2022/10// DO - 10.1016/j.corsci.2022.110578 VL - 207 SP - 110578 J2 - Corrosion Science LA - en OP - SN - 0010-938X UR - http://dx.doi.org/10.1016/j.corsci.2022.110578 DB - Crossref ER - TY - JOUR TI - Oxidation in laser-generated metal plumes AU - Kautz, Elizabeth J. AU - Phillips, Mark C. AU - Zelenyuk, Alla AU - Harilal, Sivanandan S. T2 - Physics of Plasmas AB - The temporal evolution of atoms and molecules in a laser-produced plasma was investigated using optical emission spectroscopy for several metal targets (i.e., Al, Ti, Fe, Zr, Nb, and Ta). Plasmas from metal targets were generated by focusing 1064 nm, 6 ns pulses from an Nd:YAG laser. Gas-phase oxidation/plasma chemistry was initiated by adding O2 (partial pressures up to ≈20%) to an N2 environment where the total background pressure was kept at a constant 1 atmosphere. Temporally resolved emission spectral features were used to track the gas-phase oxidation. The dynamics of atomic and molecular species were monitored using space-resolved time-of-flight emission spectroscopy. Our results highlight that the partial pressure of O2 strongly influences spectral features and molecular formation in laser-produced plasmas. Atoms and molecules co-exist in plasmas, although with different temporal histories depending on the target material due to differences in thermo- and plasma chemical reactions occurring in the plume. DA - 2022/5// PY - 2022/5// DO - 10.1063/5.0090155 UR - https://doi.org/10.1063/5.0090155 ER - TY - JOUR TI - Spatiotemporal evolution of emission and absorption signatures in a laser-produced plasma AU - Harilal, S. S. AU - Kautz, E. J. AU - Phillips, M. C. T2 - Journal of Applied Physics AB - We report spatiotemporal evolution of emission and absorption signatures of Al species in a nanosecond (ns) laser-produced plasma (LPP). The plasmas were generated from an Inconel target, which contained $\sim $ 0.4 wt.% Al, using 1064 nm, ~ 6 ns full width half maximum pulses from an Nd:YAG laser at an Ar cover gas pressure of ~ 34 Torr. The temporal distributions of the Al I (394.4 nm) transition were collected from various spatial points within the plasma employing time-of-flight (TOF) emission and laser absorption spectroscopy and they provide kinetics of the excited state and ground state population of the selected transition. The emission and absorption signatures showed multiple peaks in their temporal profiles, although they appeared at different spatial locations and times after the plasma onset. The absorption temporal profiles showed an early time signature representing shock wave propagation into the ambient gas. We also used emission and absorption spectral features for measuring various physical properties of the plasma. The absorption spectral profiles are utilized for measuring linewidths, column density, and kinetic temperature while emission spectra were used to measure excitation temperature. A comparison between excitation and the kinetic temperature was made at various spatial points in the plasma. Our results highlight that the TOF measurements provide a resourceful tool for showing the spatiotemporal LPP dynamics with higher spatial and temporal resolution than is possible with spectral measurements but are difficult to interpret without additional information on excitation temperatures and linewidths. The combination of absorption and emission TOF and spectral measurements thus provides a more complete picture of LPP spatiotemporal dynamics than is possible using any one technique alone. DA - 2022/2/14/ PY - 2022/2/14/ DO - 10.1063/5.0081597 VL - 131 IS - 6 SP - 063101 UR - https://doi.org/10.1063/5.0081597 ER - TY - JOUR TI - High-fidelity pool boiling simulations on multiple nucleation sites using interface capturing method AU - Fan, Yuqiao AU - Li, Mengnan AU - Pointer, William D. AU - Bolotnov, Igor A. T2 - NUCLEAR ENGINEERING AND DESIGN AB - Boiling has proved to be one of the most efficient means for heat transfer and is a very important phenomenon during severe accident scenarios in light water reactors. High-fidelity pool boiling simulations can provide a numerical database for improving mechanistic boiling models by allowing for specific evaluation of interactions among bubbles. Previously published pool boiling simulations investigated two nucleation sites in which bubble growth at one site suppressed nucleation at the other site. Based on previous study results, more complicated interface-capturing simulations on pool boiling were conducted using PHASTA code with locally refined unstructured mesh. First, different boundary conditions (BCs) were assessed to support robustness and reproducibility of the boiling model. Then, a scale study was conducted at a larger domain with nine nucleation sites where either nine or four nucleation sites are activated. Involving more nucleation sites increased the complexity of bubble interactions from surrounding sites. Finally, bubble departure behavior influenced by wall heat flux was investigated. When heat flux was increased, the order of bubble departure changed, but diagonal bubbles always departed after one another. The departure time interval between the first and second bubble reduced as heat flux increased. The corresponding frequency was almost linearly proportional to the heat flux. In addition, bubble departure behavior was found to be greatly influenced by the nucleation site pattern. Multiple nucleation sites resulted in superimposed inhibitive effects from surrounding sites to each bubble, which extensively delayed the departure. This new observation was not discussed in previously published works. The work presented here provides new insight on the fundamental understanding of boiling phenomena, contributes to the development of a 3D multiphase computational fluid dynamics (M-CFD) model, and provides a more comprehensive database for data-driven pool boiling studies. DA - 2022/12/1/ PY - 2022/12/1/ DO - 10.1016/j.nucengdes.2022.112004 VL - 399 SP - SN - 1872-759X KW - Pool boiling KW - Nucleation site interaction KW - High-fidelity simulation KW - Level-set method KW - Unstructured mesh ER - TY - JOUR TI - Enhanced directional extraction of very cold neutrons using a diamond nanoparticle powder reflector AU - Chernyavsky, S. M. AU - Dubois, M. AU - Korobkina, E. AU - Lychagin, E. AU - Muzychka, A. Yu AU - Nekhaev, G. AU - Nesvizhevsky, V. V. AU - Nezvanov, A. Yu AU - Strelkov, A. AU - Zhernenkov, K. N. T2 - REVIEW OF SCIENTIFIC INSTRUMENTS AB - For more than a decade, detonation nanodiamond (DND) powders have been actively studied as a material for efficient reflectors of very cold neutrons (VCNs) and cold neutrons. In this work, we experimentally demonstrate, for the first time, the possibility of enhanced directional extraction of a VCN beam using a reflector made of fluorinated DND powder. With respect to the theoretical flux calculated from an isotropic source at the bottom of the reflector cavity, the gain in the VCN flux density along the beam axis is ∼10 for the neutron velocities of ∼57 and ∼75 m/s. The use of such reflectors for enhanced directional extraction of VCN from neutron sources will make it possible to noticeably increase the neutron fluxes delivered to experiments and expand the scope of VCN applications. DA - 2022/12/1/ PY - 2022/12/1/ DO - 10.1063/5.0124833 VL - 93 IS - 12 SP - SN - 1089-7623 ER - TY - JOUR TI - A systems approach to a resilience assessment for agility AU - Hayes, Robert B. T2 - Systems Science & Control Engineering AB - This work proposes a theoretical approach to assessing agility in terms of a modified version of resilience during large-scale crisis to sustain operational reliability. The proposed method could be used on subsystem optimization or eventually scaled up to global interconnectedness enabling decision makers to optimize resource allocation and so obtain resilience and agility in troubling times along with long-term sustained prosperity. Introducing weights to various parameters can also allow customizing outcomes such as insuring equitable outcomes, environmental stewardship and proper response to emergencies or any national crisis. The provided mathematical formalism can then become a decision maker tool to predict corrective action outcomes from various responses to a crisis or alternatively to determine sensitivity and potential risk for a crisis from apparently ambient or slowly changing conditions. Ad-hoc examples are considered to demonstrate the generality of the approach. DA - 2022/12/16/ PY - 2022/12/16/ DO - 10.1080/21642583.2022.2148138 VL - 10 IS - 1 SP - 955-964 J2 - Systems Science & Control Engineering LA - en OP - SN - 2164-2583 UR - http://dx.doi.org/10.1080/21642583.2022.2148138 DB - Crossref KW - Analysis KW - artificial intelligence KW - energy and power systems KW - machine learning KW - systems ER - TY - JOUR TI - Complex bubble deformation and break-up dynamics studies using interface capturing approach (vol 3, pg 139, 2021) AU - Fan, Yuqiao AU - Fang, Jun AU - Bolotnov, Igor T2 - EXPERIMENTAL AND COMPUTATIONAL MULTIPHASE FLOW AB - The article “Complex bubble deformation and break-up dynamics studies using interface capturing approach” written by Yuqiao Fan, Jun Fang, and Igor Bolotnov, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 18 July 2020 without open access. After publication in Volume 3, Issue 3, page 139–151, the author(s) decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to © The Author(s) 2021 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/ ), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. DA - 2022/6// PY - 2022/6// DO - 10.1007/s42757-021-0127-1 VL - 4 IS - 2 SP - 191-191 SN - 2661-8877 ER - TY - JOUR TI - Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development AU - Stroth, Ulrich AU - Aguiam, D. AU - Alessi, E. AU - Angioni, C. AU - Arden, N. AU - Parra, R. Arredondo AU - Artigues, V. AU - Asunta, O. AU - Balden, M. AU - Bandaru, V. AU - Banon-Navarro, A. AU - Behler, K. AU - Bergmann, A. AU - Bergmann, M. AU - Bernardo, J. AU - Bernert, M. AU - Biancalani, A. AU - Bielajew, R. AU - Bilato, R. AU - Birkenmeier, G. AU - Blanken, T. AU - Bobkov, V. AU - Bock, A. AU - Body, T. AU - Bolzonella, T. AU - Bonanomi, N. AU - Bortolon, A. AU - Böswirth, B. AU - Bottereau, C. AU - Bottino, A. AU - Brand, H. AU - Brenzke, M. AU - Brezinsek, S. AU - Brida, D. AU - Brochard, F. AU - Bruhn, C. AU - Buchanan, J. AU - Buhler, A. AU - Burckhart, A. AU - Camenen, Y. AU - Cannas, B. AU - Megias, P. Cano AU - Carlton, D. AU - Carr, M. AU - Carvalho, P. AU - Castaldo, C. AU - Cavedon, M. AU - Cazzaniga, C. AU - Challis, C. AU - Chankin, A. AU - Cianfarani, C. T2 - Nuclear Fusion AB - Abstract An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low- Z impurity profiles. The L–H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β . The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts. DA - 2022/4/1/ PY - 2022/4/1/ DO - 10.1088/1741-4326/ac207f VL - 62 IS - 4 SP - 042006 UR - http://dx.doi.org/10.1088/1741-4326/ac207f KW - Asdex Upgrade KW - confinement KW - ELLM-free discharges ER - TY - JOUR TI - Mitigation of plasma–wall interactions with low-Z powders in DIII-D high confinement plasmas AU - Effenberg, Florian AU - Bortolon, Alessandro AU - Casali, Livia AU - Nazikian, Raffi AU - Bykov, Igor AU - Scotti, Filippo AU - Wang, Huiqian AU - Fenstermacher, Max AU - Lunsford, Robert AU - Nagy, Alexander AU - Grierson, Brian AU - Laggner, Florian M. AU - maingi, AU - DIII-D Team, T2 - Nuclear Fusion AB - Experiments with low-Z powder injection in DIII-D high confinement discharges demonstrated increased divertor dissipation and detachment while maintaining good core energy confinement. Lithium (Li), boron (B), and boron nitride (BN) powders were injected in high-confinement mode plasmas ($I_p=$1 MA, $B_t=$2 T, $P_{NB}=$6 MW, $\langle n_e\rangle=3.6-5.0\cdot10^{19}$ m$^{-3}$) into the upper small-angle slot (SAS) divertor for 2-s intervals at constant rates of 3-204 mg/s. The multi-species BN powders at a rate of 54 mg/s showed the most substantial increase in divertor neutral compression by more than an order of magnitude and lasting detachment with minor degradation of the stored magnetic energy $W_{mhd}$ by 5%. Rates of 204 mg/s of boron nitride powder further reduce ELM-fluxes on the divertor but also cause a drop in confinement performance by 24% due to the onset of an $n=2$ tearing mode. The application of powders also showed a substantial improvement of wall conditions manifesting in reduced wall fueling source and intrinsic carbon and oxygen content in response to the cumulative injection of non-recycling materials. The results suggest that low-Z powder injection, including mixed element compounds, is a promising new core-edge compatible technique that simultaneously enables divertor detachment and improves wall conditions during high confinement operation. DA - 2022/10/1/ PY - 2022/10/1/ DO - 10.1088/1741-4326/ac899d VL - 62 IS - 10 SP - 106015 UR - http://dx.doi.org/10.1088/1741-4326/ac899d KW - divertor power exhaust KW - wall conditioning KW - detachment KW - impurity seeding KW - low recycling KW - lithium KW - boron ER - TY - JOUR TI - DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy AU - Fenstermacher, Max AU - Abbate, J. AU - Abe, S. AU - Abrams, Tyler AU - Adams, M. AU - Adamson, B. AU - Aiba, N. AU - Akiyama, T. AU - Aleynikov, P. AU - Allen, E. AU - Allen, S. AU - Anand, H. AU - Anderson, J. AU - Andrew, Y. AU - Andrews, T. AU - Appelt, D. AU - Arbon, R. AU - Ashikawa, N. AU - Ashourvan, A. AU - Aslin, M. AU - Asnis, Y. AU - Austin, M. AU - Ayala, D. AU - Bak, J. AU - Bandyopadhyay, I. AU - Banerjee, S. AU - Barada, Kshitish AU - Bardoczi, L. AU - Barr, Jayson AU - Bass, E. AU - Battaglia, D. AU - Battey, A. AU - Baumgartner, W. AU - Baylor, L. AU - Beckers, J. AU - Beidler, M. AU - Belli, E. AU - Berkery, J. AU - Bernard, T. AU - Bertelli, N. AU - Beurskens, M. AU - Bielajew, R. AU - Bilgili, S. AU - Biswas, B. AU - Blondel, S. AU - Boedo, J. AU - Bogatu, I. AU - Boivin, R. AU - Bolzonella, T. AU - Bongard, M. AU - Bonnin, X. T2 - Nuclear Fusion AB - Abstract DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter- I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high- Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L–H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co- I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation. DA - 2022/4/1/ PY - 2022/4/1/ DO - 10.1088/1741-4326/ac2ff2 VL - 62 IS - 4 SP - 042024 UR - http://dx.doi.org/10.1088/1741-4326/ac2ff2 KW - DIII-D KW - tokamak KW - fusion energy KW - plasma physics KW - core-edge integration ER - TY - JOUR TI - NSTX-U theory, modeling and analysis results AU - Guttenfelder, W. AU - Battaglia, D.J. AU - Belova, E. AU - Bertelli, N. AU - Boyer, M.D. AU - Chang, C.S. AU - Diallo, A. AU - Duarte, V.N. AU - Ebrahimi, F. AU - Emdee, E.D. AU - Ferraro, N. AU - Fredrickson, E. AU - Gorelenkov, N.N. AU - Heidbrink, W. AU - Ilhan, Z. AU - Kaye, S.M. AU - Kim, E.-H. AU - Kleiner, A. AU - Laggner, F. AU - Lampert, M. AU - Lestz, J.B. AU - Liu, C. AU - Liu, D. AU - Looby, T. AU - Mandell, N. AU - Maingi, R. AU - Myra, J.R. AU - Munaretto, S. AU - Podestà, M. AU - Rafiq, T. AU - Raman, R. AU - Reinke, M. AU - Ren, Y. AU - Ruiz, J. Ruiz AU - Scotti, F. AU - Shiraiwa, S. AU - Soukhanovskii, V. AU - Vail, P. AU - Wang, Z.R. AU - Wehner, W. AU - White, A.E. AU - White, R.B. AU - Woods, B.J.Q. AU - Yang, J. AU - Zweben, S.J. AU - Banerjee, S. AU - Barchfeld, R. AU - Bell, R.E. AU - Berkery, J.W. AU - Bhattacharjee, A. AU - Bierwage, A. AU - Canal, G.P. AU - Chen, X. AU - Clauser, C. AU - Crocker, N. AU - Domier, C. AU - Evans, T. AU - Francisquez, M. AU - Gan, K. AU - Gerhardt, S. AU - Goldston, R.J. AU - Gray, T. AU - Hakim, A. AU - Hammett, G. AU - Jardin, S. AU - Kaita, R. AU - Koel, B. AU - Kolemen, E. AU - Ku, S.-H. AU - Kubota, S. AU - LeBlanc, B.P. AU - Levinton, F. AU - Lore, J.D. AU - Luhmann, N. AU - Lunsford, R. AU - Maqueda, R. AU - Menard, J.E. AU - Nichols, J.H. AU - Ono, M. AU - Park, J.-K. AU - Poli, F. AU - Rhodes, T. AU - Riquezes, J. AU - Russell, D. AU - Sabbagh, S.A. AU - Schuster, E. AU - Smith, D.R. AU - Stotler, D. AU - Stratton, B. AU - Tritz, K. AU - Wang, W. AU - Wirth, B. T2 - Nuclear Fusion AB - Abstract The mission of the low aspect ratio spherical tokamak NSTX-U is to advance the physics basis and technical solutions required for optimizing the configuration of next-step steady-state tokamak fusion devices. NSTX-U will ultimately operate at up to 2 MA of plasma current and 1 T toroidal field on axis for 5 s, and has available up to 15 MW of neutral beam injection power at different tangency radii and 6 MW of high harmonic fast wave heating. With these capabilities NSTX-U will develop the physics understanding and control tools to ramp-up and sustain high performance fully non-inductive plasmas with large bootstrap fraction and enhanced confinement enabled via the low aspect ratio, high beta configuration. With its unique capabilities, NSTX-U research also supports ITER and other critical fusion development needs. Super-Alfvénic ions in beam-heated NSTX-U plasmas access energetic particle (EP) parameter space that is relevant for both α-heated conventional and low aspect ratio burning plasmas. NSTX-U can also generate very large target heat fluxes to test conventional and innovative plasma exhaust and plasma facing component solutions. This paper summarizes recent analysis, theory and modelling progress to advance the tokamak physics basis in the areas of macrostability and 3D fields, EP stability and fast ion transport, thermal transport and pedestal structure, boundary and plasma material interaction, RF heating, scenario optimization and real-time control. DA - 2022/4/1/ PY - 2022/4/1/ DO - 10.1088/1741-4326/ac5448 VL - 62 IS - 4 SP - 042023 UR - http://dx.doi.org/10.1088/1741-4326/ac5448 KW - NSTX-U KW - NSTX KW - overview ER - TY - JOUR TI - Deconvolving the roles of E × B shear and pedestal structure in the energy confinement quality of super H-mode experiments AU - Garofalo, Andrea M. AU - Ding, Siye AU - Solomon, W.M. AU - Grierson, Brian AU - Jian, X. AU - Osborne, T.H. AU - Holland, Christopher AU - Knolker, Matthias AU - Laggner, F.M. AU - Chrystal, Colin AU - Marinoni, A. AU - Petty, Craig T2 - Nuclear Fusion AB - Abstract Analysis of ‘super H-mode’ experiments on DIII-D has put forward that high plasma toroidal rotation, not high pedestal, plays the essential role in achieving energy confinement quality H 98y2 ≫ 1 (Ding et al 2020 Nucl. Fusion 60 034001). Recently, super H-mode experiments with variable input torque have confirmed that high rotation shear discharges have very high levels of H 98y2 (>1.5), independent of the pedestal height, and that high pedestal discharges with low rotation shear have levels of H 98y2 only slightly above 1 (⩽1.2). Although some increase in stored energy with higher pedestal occurs, the energy confinement quality mainly depends on the toroidal rotation shear, which varies according to different levels of injected neutral beam torque per particle. Quasi-linear gyrofluid modeling achieves a good match of the experiment when including the E × B shear; without including plasma rotation, the modeling predicts a confinement quality consistent with the empirical observation of H 98y2 ∼ 1.2 at low rotation. Nonlinear gyrokinetic transport modeling shows that the effect of E × B turbulence stabilization is far larger than other mechanisms, such as the so-called hot-ion stabilization ( T i / T e ) effect. Consistent with these experimental and modeling results are previous simulations of the ITER baseline scenario using a super H-mode pedestal solution (Solomon et al 2016 Phys. Plasmas 23 056105), which showed the potential to exceed the Q = 10 target if the pedestal density could be increased above the Greenwald limit. A close look at these simulations reveals that the predicted energy confinement quality is below 1 even at the highest pedestal pressure. The improvement in Q at higher pedestal density is due to the improved fusion power generation at the higher core density associated with higher pedestal density, not to an improved energy confinement quality. DA - 2022/5/1/ PY - 2022/5/1/ DO - 10.1088/1741-4326/ac4d63 VL - 62 IS - 5 SP - 056008 UR - http://dx.doi.org/10.1088/1741-4326/ac4d63 KW - tokamak KW - pedestal KW - rotation KW - confinement quality KW - fusion performance KW - theoretical predictions ER - TY - JOUR TI - Reducing the L-H transition power threshold in ITER-similar-shape DIII-D hydrogen plasmas AU - Schmitz, Lothar AU - Wilcox, Robert AU - Shiraki, Daisuke AU - Rhodes, Terry AU - Yan, Zheng AU - McKee, George AU - Callahan, Kyle AU - Chrystal, Colin AU - Haskey, Shaun AU - Liu, Yueqiang AU - Laggner, Florian M. AU - Zeng, Lei AU - Osborne, Thomas AU - Grierson, Brian AU - Paz-Soldan, Carlos AU - Leuthold, Nils AU - Lyons, B.C. AU - Gohil, Punit AU - Petty, Craig T2 - Nuclear Fusion AB - Abstract Recent dedicated DIII-D experiments in low-torque, ITER-similar-shape (ISS) hydrogen plasmas (at a plasma current I p ∼ 1.5 MA and ITER-similar edge safety factor q 95 ∼ 3.6) show that the L-H transition power threshold P LH can be reduced substantially (∼30%) with L-mode helium admixtures n He / n e ⩽ 25%. In the ensuing H-mode, helium ion fractions n He / n H remain below 25%. H-mode normalized pressure and confinement quality are only slightly affected by helium seeding, and Z eff ⩽ 2.15 (including helium and carbon content). The plasmas investigated here are electron-heat dominated, with temperatures T e (0)/ T i (0) ⩾ 1 and edge heat flux ratio Q e / Q i ( ρ = 0.95) ∼ 1.2–1.5. Without mitigation, P LH is higher by a factor of 2–3 in comparison to similar ISS deuterium plasmas. ISS hydrogen plasmas with lower plasma current I p ∼ 1 MA (increased edge safety factor q 95 ∼ 5.1) exhibit a substantially lower power threshold. This plasma current dependence, also observed previously on ASDEX-U and in JET, is not accounted for by the commonly used 2008 ITPA multi-machine threshold scaling, but could potentially allow H-mode access at marginal heating power during the initial plasma current ramp-up. Attempts to reduce P LH with low-field- and high-field-side hydrogen pellet injection, using 1.7 mm diameter pellets, have not demonstrated a robust threshold reduction, in contrast to successful earlier experiments with larger 2.7 mm pellets. Techniques for reducing P LH are very important for ITER, in particular for accessing H-mode in hydrogen plasmas during the Pre-Fusion Power Operation-1 (PFPO-1) campaign with marginal auxiliary heating power (20–30 MW of ECH). DA - 2022/12/1/ PY - 2022/12/1/ DO - 10.1088/1741-4326/ac94e1 VL - 62 IS - 12 SP - 126050 UR - http://dx.doi.org/10.1088/1741-4326/ac94e1 KW - L-H transition KW - ITER KW - hydrogen KW - helium ER - TY - JOUR TI - Analyzing the effect of pressure on the properties of point defects in ?U-Mo through atomistic simulations (vol 15, pg 874. 2022) AU - Beeler, Benjamin AU - Zhang, Yongfeng AU - Hasan, A. T. M. Jahid AU - Park, Gyuchul AU - Hu, Shenyang AU - Mei, Zhi-Gang T2 - MRS ADVANCES DA - 2022/12/5/ PY - 2022/12/5/ DO - 10.1557/s43580-022-00436-7 VL - 12 SP - SN - 2059-8521 UR - https://doi.org/10.1557/s43580-022-00436-7 ER - TY - JOUR TI - Corrosion behavior of a series of combinatorial physical vapor deposition coatings on SiC in a simulated boiling water reactor environment AU - Schoell, Ryan AU - Kabel, Joey AU - Lam, Sebastian AU - Sharma, Amit AU - Michler, Johann AU - Hosemann, Peter AU - Kaoumi, Djamel T2 - JOURNAL OF NUCLEAR MATERIALS AB - The simulated boiling water condition corrosion properties of multilayer and combinatorial physical vapor deposition metal coatings (Zr, Cr, and/or Ti) deposited on a SiCf-SiC composite were investigated. Various compositions within the ternary system were corroded to the most suitable composition preventing underlying SiCf-SiC from further attack. Mass measurements and visual observations were conducted to identify which coatings formed protective oxides and which coatings spalled. Transmission electron microscopy was conducted to observe the microstructure of the physical vapor deposition metal layer before and after corrosion as well as identify the oxide which were forming. DA - 2022/12/15/ PY - 2022/12/15/ DO - 10.1016/j.jnucmat.2022.154022 VL - 572 SP - SN - 1873-4820 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85138461418&partnerID=MN8TOARS KW - PVD KW - Corrosion KW - TEM KW - Combinatorial ER - TY - JOUR TI - Effect of thermal oxidation on helium implanted 316L stainless steel AU - Hong, Minsung AU - Morales, Angelica Lopez AU - Chan, Ho Lun AU - Macdonald, Digby D. AU - Balooch, Mehdi AU - Xie, Yujun AU - Romanovskaia, Elena AU - Scully, John R. AU - Kaoumi, Djamel AU - Hosemann, Peter T2 - JOURNAL OF APPLIED PHYSICS AB - The effect of thermal oxide layer on He implanted 316L stainless steel was studied to evaluate experimentally how thermal oxidation affects the diffusion and distribution of He in the material. In the case of thermal oxidation of a He implanted sample, with an increase in oxidation time, the max swelling height increases logarithmically as a function of time and finally saturates for all samples except for the lowest dose of implanted He. Concerning TEM results, two void regions are identified. Similar to the calculation, the total irradiated depth was around 250 nm and the large void region was formed around 100–150 nm depth. On the other hand, the small void region was observed immediately under oxide layer from the thermal oxidation. In contrast, there were no voids in the altered zone near the metal/oxide interface in the non-thermal oxidized/He implanted sample. This description of the phenomena was justified using the Kirkendall effect and the Point Defect Model. DA - 2022/11/14/ PY - 2022/11/14/ DO - 10.1063/5.0122487 VL - 132 IS - 18 SP - SN - 1089-7550 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85144284308&partnerID=MN8TOARS ER - TY - JOUR TI - Chemical and elemental mapping of spent nuclear fuel sections by soft X-ray spectromicroscopy AU - Ditter, Alexander Scott AU - Smiles, Danil E. AU - Lussier, Daniel AU - Altman, Alison B. AU - Bachhav, Mukesh AU - He, Lingfeng AU - Mara, Michael W. AU - Degueldre, Claude AU - Minasian, Stefan G. AU - Shuh, David K. T2 - Journal of Synchrotron Radiation AB - Soft X-ray spectromicroscopy at the O K-edge, U N4,5-edges and Ce M4,5-edges has been performed on focused ion beam sections of spent nuclear fuel for the first time, yielding chemical information on the sub-micrometer scale. To analyze these data, a modification to non-negative matrix factorization (NMF) was developed, in which the data are no longer required to be non-negative, but the non-negativity of the spectral components and fit coefficients is largely preserved. The modified NMF method was utilized at the O K-edge to distinguish between two components, one present in the bulk of the sample similar to UO2 and one present at the interface of the sample which is a hyperstoichiometric UO2+x species. The species maps are consistent with a model of a thin layer of UO2+x over the entire sample, which is likely explained by oxidation after focused ion beam (FIB) sectioning. In addition to the uranium oxide bulk of the sample, Ce measurements were also performed to investigate the oxidation state of that fission product, which is the subject of considerable interest. Analysis of the Ce spectra shows that Ce is in a predominantly trivalent state, with a possible contribution from tetravalent Ce. Atom probe analysis was performed to provide confirmation of the presence and localization of Ce in the spent fuel. DA - 2022/1/1/ PY - 2022/1/1/ DO - 10.1107/S1600577521012315 VL - 29 IS - 1 SP - 67-79 UR - https://doi.org/10.1107/S1600577521012315 KW - spent nuclear fuel KW - STXM KW - oxygen K-edge KW - focused ion beam sections ER - TY - JOUR TI - Compositionally graded specimen made by laser additive manufacturing as a high-throughput method to study radiation damages and irradiation-assisted stress corrosion cracking AU - Yang, Jingfan AU - Hawkins, Laura AU - Song, Miao AU - He, Lingfeng AU - Bachhav, Mukesh AU - Pan, Qingyu AU - Shao, Lin AU - Schwen, Daniel AU - Lou, Xiaoyuan T2 - Journal of Nuclear Materials AB - This study demonstrates the feasibility of using compositionally gradient specimens, fabricated by laser additive manufacturing (AM) and post-AM thermo-mechanical treatment, to accelerate alloy synthesis, radiation experiment, and the assessment of irradiation properties in light water reactor environments. The effects of minor Hafnium (Hf) doping in austenitic 316L stainless steel (SS) was selected as the topic of interest. By comparing to the data in literature, we confirmed that the compositionally graded specimen produces the same trend of void swelling, dislocation loops, radiation-induced segregation (RIS), radiation hardening as the wrought specimen produced by cast/forging process. Hf suppressed most radiation damages through strong interaction with point defects. The work also demonstrates the use of compositionally gradient specimens to study the irradiation-assisted stress corrosion cracking (IASCC) susceptibility of Hf-modified SS. While the suppression of radiation hardening and RIS are consistent with the IASCC mitigation by Hf, we emphasize Hf can alter the intrinsic deformation behavior of 316L SS, which reduces grain-boundary strain localization. The advantages and challenges of using compositionally gradient design for high-throughput nuclear alloy development and qualification are also discussed. DA - 2022/3// PY - 2022/3// DO - 10.1016/j.jnucmat.2021.153493 VL - 560 SP - 153493 UR - http://dx.doi.org/10.1016/j.jnucmat.2021.153493 KW - Direct energy deposition (DED) additively KW - manufacturing (AM) KW - High-throughput alloy development KW - Radiation hardening KW - Irradiation-assisted stress corrosion cracking  KW - (IASCC) KW - Stainless steel KW - Radiation-induced segregation ER - TY - JOUR TI - Visualizing time-dependent microstructural and chemical evolution during molten salt corrosion of Ni-20Cr model alloy using correlative quasi in situ TEM and in situ synchrotron X-ray nano-tomography AU - Bawane, Kaustubh AU - Liu, Xiaoyang AU - Gakhar, Ruchi AU - Woods, Michael AU - Ge, Mingyuan AU - Xiao, Xianghui AU - Lee, Wah-Keat AU - Halstenberg, Philip AU - Dai, Sheng AU - Mahurin, Shannon AU - Pimblott, Simon M. AU - Wishart, James F. AU - Chen-Wiegart, Yu-chen Karen AU - He, Lingfeng T2 - Corrosion Science AB - In situ monitoring of corrosion processes is important to fundamentally understand the kinetics and evolution of materials in harsh environments. A quasi in situ transmission electron microscopy technique was utilized to study microstructural and chemical evolution of a Ni-20Cr disc sample exposed to molten KCl-MgCl2 salt for 60 s in consecutive 20 s iterations. In situ synchrotron X-ray nano-tomography was performed to characterize the morphological evolution of a Ni-20Cr microwire exposed to molten KCl-MgCl2. Both techniques captured key corrosion events and revealed mechanisms at different time and length scales, potentially bringing greater insights and deeper understanding beyond conventional analysis. DA - 2022/2// PY - 2022/2// DO - 10.1016/j.corsci.2021.109962 VL - 195 SP - 109962 UR - http://dx.doi.org/10.1016/j.corsci.2021.109962 KW - Molten salt corrosion KW - quasi in situ TEM KW - dealloying KW - X-ray nano-tomography KW - in situ synchrotron ER - TY - JOUR TI - Sensitization, desensitization, and carbide evolution of Alloy 800H made by laser powder bed fusion AU - Yang, Jingfan AU - Liu, Xiang AU - Song, Miao AU - He, Lingfeng AU - Bankson, Stephen AU - Hamilton, Michael AU - Prorok, Bart AU - Lou, Xiaoyuan T2 - Additive Manufacturing AB - Additively manufactured (AM) Alloy 800H made by laser powder bed fusion (L-PBF) exhibited a greater degree of sensitization than wrought 800H, leading to both intergranular and intercellular corrosion. Dislocation cellular boundaries showed mild Cr depletion as compared to high-angle grain boundaries (HAGBs). Boundary misorientation of < 5⁰ was found mitigating sensitization. Carbide growth in AM 800H was controlled by particle net growth at the early stage and Ostwald ripening at the later stage. Cellular structure was confirmed producing faster elemental diffusion than bulk diffusion and random dislocation structures by cold rolling, and leading more rapid carbide growth, chromium depletion, and desensitization on HAGBs. Sensitization along cellular boundaries is not the main cause of intercellular corrosion in the sensitized AM Alloy 800H. DA - 2022/2// PY - 2022/2// DO - 10.1016/j.addma.2021.102547 VL - 50 SP - 102547 UR - http://dx.doi.org/10.1016/j.addma.2021.102547 KW - Alloy 800H KW - Laser powder bed fusion additive KW - manufacturing KW - Sensitization KW - Carbide formation KW - Dislocation cellular structures ER - TY - JOUR TI - Comprehensive characterization of irradiation induced defects in ceria: Impact of point defects on vibrational and optical properties AU - Chauhan, Vinay S. AU - Ferrigno, Joshua AU - Adnan, Saqeeb AU - Pakarinen, Janne AU - He, Lingfeng AU - Hurley, David H. AU - Khafizov, Marat T2 - Journal of Applied Physics AB - Validation of multiscale microstructure evolution models can be improved when standard microstructure characterization tools are coupled with methods sensitive to individual point defects. We demonstrate how electronic and vibrational properties of defects revealed by optical absorption and Raman spectroscopies can be used to compliment transmission electron microscopy (TEM) and x-ray diffraction (XRD) in the characterization of microstructure evolution in ceria under non-equilibrium conditions. Experimental manifestation of non-equilibrium conditions was realized by exposing cerium dioxide (CeO2) to energetic protons at elevated temperature. Two sintered polycrystalline CeO2 samples were bombarded with protons accelerated to a few MeVs. These irradiation conditions produced a microstructure with resolvable extended defects and a significant concentration of point defects. A rate theory (RT) model was parametrized using the results of TEM, XRD, and thermal conductivity measurements to infer point defect concentrations. An abundance of cerium sublattice defects suggested by the RT model is supported by Raman spectroscopy measurements, which show peak shift and broadening of the intrinsic T2g peak and emergence of new defect peaks. Additionally, spectroscopic ellipsometry measurements performed in lieu of optical absorption reveals the presence of Ce3+ ions associated with oxygen vacancies. This work lays the foundation for a coupled approach that considers a multimodal characterization of microstructures to guide and validate complex defect evolution models. DA - 2022/8/28/ PY - 2022/8/28/ DO - 10.1063/5.0099189 UR - https://doi.org/10.1063/5.0099189 ER - TY - JOUR TI - Unraveling small-scale defects in irradiated ThO2 using kinetic Monte Carlo simulations AU - Jiang, Chao AU - He, Lingfeng AU - Dennett, Cody A. AU - Khafizov, Marat AU - Mann, J. Matthew AU - Hurley, David H. T2 - Scripta Materialia AB - Point defects and their clusters generated through irradiation can have significant impact on the physical and mechanical properties of materials. However, direct experimental visualization of these small-scale defects using high-resolution scanning transmission electron microscopy remains a challenging task. Here, using thorium dioxide (ThO2) with the fluorite structure as a model system, we demonstrate the use of ab initio basin-hopping simulations in synergy with object kinetic Monte Carlo simulations as a powerful tool for identifying small defect complexes in irradiated materials. In addition to providing quantitative insights into defect evolution in ThO2 under irradiation, our study reveals an unexpected role of bound anti-Schottky defect clusters in mediating defect transport. Remarkably, despite their poor thermal stability against dissociation at high temperatures, the transient formation of bound anti-Schottky defects under irradiation and their subsequent migration provide the dominant mechanism for the growth of large interstitial loops that have been experimentally observed in ThO2. DA - 2022/6// PY - 2022/6// DO - 10.1016/j.scriptamat.2022.114684 UR - https://doi.org/10.1016/j.scriptamat.2022.114684 KW - Density functional theory (DFT) KW - Monte Carlo simulation KW - Scanning KW - transmission electron microscopy KW - (STEM) KW - Defects KW - Oxides ER - TY - JOUR TI - Synthesis and characterization of uranium trichloride in alkali-metal chloride media AU - Herrmann, Steven D. AU - Zhao, Haiyan AU - Bawane, Kaustubh K. AU - He, Lingfeng AU - Tolman, Kevin R. AU - Pu, Xiaofei T2 - Journal of Nuclear Materials AB - Given a growing interest in uranium salts for pyrochemical processing of used fuel and uranium-fueled molten salt reactors, the synthesis of uranium trichloride in alkali-metal chloride media was investigated in a series of four experiments. Specifically, uranium metal powder and uranium hydride powder were prepared and separately blended with ammonium chloride and lithium chloride – potassium chloride eutectic in two runs, while the same powders were separately blended with ammonium chloride and sodium chloride in two additional runs. Each of the lithium chloride – potassium chloride containing blends was slowly heated to 923 K, while those containing sodium chloride were heated to 1123 K. During each heat up, the ammonium chloride sublimed into gaseous ammonia and hydrogen chloride, leading to the chlorination of uranium metal or uranium hydride and the formation of molten salt solutions of the respective chlorides. Experimental conditions were incorporated in the runs to promote formation of uranium trichloride over uranium tetrachloride in the respective media. Molten samples of each run product were taken and characterized via chemical analyses, diffractometry, and microscopy. The final products from each run were dark dense ingots of the respective salt systems with uranium concentrations ranging from 44 to 51 wt%. Chemical analyses and diffractometry identified the predominant presence of uranium trichloride in these systems; however, a possible minor presence of uranium tetrachloride could not be conclusively dismissed. DA - 2022/7// PY - 2022/7// DO - 10.1016/j.jnucmat.2022.153728 VL - 565 SP - 153728 UR - https://doi.org/10.1016/j.jnucmat.2022.153728 KW - Uranium trichloride synthesis KW - Uranium trichloride characterization KW - Uranium metal chlorination KW - Uranium hydride chlorination KW - Ammonium chloride ER - TY - JOUR TI - Dislocation loop evolution in Kr‐irradiated ThO2 AU - He, Lingfeng AU - Yao, Tiankai AU - Bawane, Kaustubh AU - Jin, Miaomiao AU - Jiang, Chao AU - Liu, Xiang AU - Chen, Wei‐Ying AU - Mann, J. Matthew AU - Hurley, David H. AU - Gan, Jian AU - Khafizov, Marat T2 - Journal of the American Ceramic Society AB - Abstract The early stage of microstructural evolution of ThO 2 , under krypton irradiation at 600, 800, and 1000°C, was investigated using in situ transmission electron microscopy (TEM). Dislocation loops grew faster, whereas their number density decreased with increasing irradiation temperature. Loop density was found to decrease with ion dose. Interstitial dislocation loops, including Frank loops with Burgers vector of a /3〈111〉 and perfect loops with Burgers vector of a /2〈110〉, were determined by traditional TEM and atomic resolution–scanning TEM techniques. Atomistic and mesoscale level modeling are performed to interpret experimental observations. The migration energy barriers of defects in ThO 2 were calculated using density‐functional theory. The energetics of different dislocation loop types were studied using molecular dynamics simulations. Loop density and diameter were analyzed using a kinetic rate theory model that considers stoichiometric loop evolution. This analysis reveals that loop growth is governed by the mobility of cation interstitials, whereas loop nucleation is determined by the mobility of anion defects. Lastly, a rate theory model was used to extract the diffusion coefficients of thorium interstitials, oxygen interstitials, and vacancies. DA - 2022/8// PY - 2022/8// DO - 10.1111/jace.18478 UR - https://doi.org/10.1111/jace.18478 KW - defects KW - dislocations KW - microstructure KW - oxides KW - transmission electron microscopy ER - TY - JOUR TI - Thermal Energy Transport in Oxide Nuclear Fuel AU - Hurley, David H. AU - El-Azab, Anter AU - Bryan, Matthew S. AU - Cooper, Michael W. D. AU - Dennett, Cody A. AU - Gofryk, Krzysztof AU - He, Lingfeng AU - Khafizov, Marat AU - Lander, Gerard H. AU - Manley, Michael E. AU - Mann, J. Matthew AU - Marianetti, Chris A. AU - Rickert, Karl AU - Selim, Farida A. AU - Tonks, Michael R. AU - Wharry, Janelle P. T2 - Chemical Reviews AB - To efficiently capture the energy of the nuclear bond, advanced nuclear reactor concepts seek solid fuels that must withstand unprecedented temperature and radiation extremes. In these advanced fuels, thermal energy transport under irradiation is directly related to reactor performance as well as reactor safety. The science of thermal transport in nuclear fuel is a grand challenge as a result of both computational and experimental complexities. Here we provide a comprehensive review of thermal transport research on two actinide oxides: one currently in use in commercial nuclear reactors, uranium dioxide (UO2), and one advanced fuel candidate material, thorium dioxide (ThO2). In both materials, heat is carried by lattice waves or phonons. Crystalline defects caused by fission events effectively scatter phonons and lead to a degradation in fuel performance over time. Bolstered by new computational and experimental tools, researchers are now developing the foundational work necessary to accurately model and ultimately control thermal transport in advanced nuclear fuels. We begin by reviewing research aimed at understanding thermal transport in perfect single crystals. The absence of defects enables studies that focus on the fundamental aspects of phonon transport. Next, we review research that targets defect generation and evolution. Here the focus is on ion irradiation studies used as surrogates for damage caused by fission products. We end this review with a discussion of modeling and experimental efforts directed at predicting and validating mesoscale thermal transport in the presence of irradiation defects. While efforts in these research areas have been robust, challenging work remains in developing holistic tools to capture and predict thermal energy transport across widely varying environmental conditions. DA - 2022/2/9/ PY - 2022/2/9/ DO - 10.1021/acs.chemrev.1c00262 UR - https://doi.org/10.1021/acs.chemrev.1c00262 ER - TY - JOUR TI - Preparation and strengthening mechanism of prestressed ceramic tile components AU - Sun, Yi AU - Wu, Tianye AU - Bao, Yiwang AU - Li, Yueming AU - Wan, Detian AU - Li, Kai AU - He, Lingfeng T2 - International Journal of Applied Ceramic Technology AB - Abstract To improve the flexural strength of ceramic tiles, a surface strengthening method is presented in this work. By cofiring coating and substrate, residual compressive stress is introduced in the coating. The phase composition and morphological characteristics of coating materials and the influences of coefficient of thermal expansion (CTE) and coating thickness on the flexural strength have been investigated. The prestressed ceramic tile is prepared by pressureless sintering a green body coated with a low CTE coating at 1200°C. The CTE of green body and optimal coating is 7.85 × 10 −6 °C −1 and 5.69 × 10 −6 °C −1 , respectively. The flexural strength of prestressed porcelain tiles (89 ± 3 MP) has been increased by 102% when the coating thickness is 67 µm compared to their uncoated counterpart (44 ± 3 MPa). This simple surface strengthening method of ceramic tiles is cost‐efficient and economical for large‐scale industrial applications. DA - 2022/1// PY - 2022/1// DO - 10.1111/ijac.13757 UR - https://doi.org/10.1111/ijac.13757 KW - ceramic tiles KW - coating KW - flexural strength KW - pressureless sintering KW - prestressed components ER - TY - JOUR TI - Microstructural changes of proton irradiated Hastelloy-N and in situ micropillar compression testing of one single grain at different local damage levels AU - Pena, Miguel AU - Morell-Pacheco, Andres AU - Shiau, Ching-Heng AU - Kombaiah, Boopathy AU - He, Lingfeng AU - Hawkins, Laura AU - Gabriel, Adam AU - Garner, Frank A. AU - Shao, Lin T2 - Journal of Nuclear Materials AB - In situ micropillar compression was used to study the deformation of proton-irradiated Hastelloy-N at different damage levels. Multiple pillars were prepared from a single grain along the cross-section of 2.5 MeV proton-irradiated Hastelloy-N. Depending on the location of micropillars, the critical resolved shear stress was obtained as a function of local damage levels. Such an approach eliminates the variation of yield stress due to the difference in the Schmid factor . Microstructural characterization showed complicated defect structures , including (a) dislocation loops with many in corduroy-like alignments, (2) dislocations pile up, (3) element segregation, and (4) twin boundaries. Silicon atoms are found to segregate at dislocation lines , loops, and twin boundaries and form complicated patterns at nanometer scales. These complexities make it difficult to conclude which hardening mechanism contributes the most to the hardness changes. The critical resolved shear stress, τ c r s s , and hardening exponents were both extracted as a function of displacements per atom values up to 2.3. There was a 60% increase in τ c r s s at the highest damage level. DA - 2022/11// PY - 2022/11// DO - 10.1016/j.jnucmat.2022.153939 UR - https://doi.org/10.1016/j.jnucmat.2022.153939 KW - Hastelloy N KW - Irradiation KW - Hardening KW - Pillar compression ER - TY - JOUR TI - Development of machine learning framework for interface force closures based on bubble tracking data AU - Tai, Cheng-Kai AU - Evdokimov, Ilya AU - Schlegel, Fabian AU - Bolotnov, Igor A. AU - Lucas, Dirk T2 - NUCLEAR ENGINEERING AND DESIGN AB - Interfacial force closures in the two-fluid model play a critical role for the predictive capabilities of void fraction distribution. However, the practices of interfacial force modeling have long been challenged by the inherent physical complexity of the two-phase flows. The rapidly expanding computational capabilities in the recent years have made high-fidelity data from the interface-captured direct numerical simulation become more available, and hence potential for data-driven interfacial force modeling has prevailed. In this work, we established a data-driven modeling framework integrated to the HZDR multiphase Eulerian-Eulerian framework for computational fluid dynamics simulations. The data-driven framework is verified in a benchmark problem, where a feedforward neural network managed to capture the non-linear mapping between bubble Reynolds number and drag coefficient and reproduce the void distribution resulting from the baseline model in the test case. The second focus is on utilizing the bubble tracking data set to form a closure for the bubble drag in the turbulent bubbly flow, in which the drag coefficient is set to be correlated with the bubble Reynolds number and the Eötvös number. Pseudo-steady state filtering in the Frenet Frame was carried out to obtain the drag coefficient from the turbulent bubbly flow data. The performance of the data-driven drag model is also examined through a case study, where improvement of model’s prediction near-wall is regarded necessary. Discussion and further plans of investigation are provided. DA - 2022/12/1/ PY - 2022/12/1/ DO - 10.1016/j.nucengdes.2022.112032 VL - 399 SP - SN - 1872-759X KW - Direct numerical simulation KW - Data-driven modeling KW - Interfacial force modeling KW - Machine learning KW - Eulerian-Eulerian approach ER - TY - JOUR TI - A Novel Method for Controlling Crud Deposition in Nuclear Reactors Using Optimization Algorithms and Deep Neural Network Based Surrogate Models AU - Andersen, Brian AU - Hou, Jason AU - Godfrey, Andrew AU - Kropaczek, Dave T2 - Eng AB - This work presents the use of a high-fidelity neural network surrogate model within a Modular Optimization Framework for treatment of crud deposition as a constraint within light-water reactor core loading pattern optimization. The neural network was utilized for the treatment of crud constraints within the context of an advanced genetic algorithm applied to the core design problem. This proof-of-concept study shows that loading pattern optimization aided by a neural network surrogate model can optimize the manner in which crud distributes within a nuclear reactor without impacting operational parameters such as enrichment or cycle length. Several analysis methods were investigated. Analysis found that the surrogate model and genetic algorithm successfully minimized the deviation from a uniform crud distribution against a population of solutions from a reference optimization in which the crud distribution was not optimized. Strong evidence is presented that shows boron deposition in crud can be optimized through the loading pattern. This proof-of-concept study shows that the methods employed provide a powerful tool for mitigating the effects of crud deposition in nuclear reactors. DA - 2022/11/23/ PY - 2022/11/23/ DO - 10.3390/eng3040036 UR - https://doi.org/10.3390/eng3040036 ER - TY - JOUR TI - EPR Investigation of Temporal and Thermal Stability of Irradiated Sweeteners AU - Abdelrahman, Fatma M. AU - Hayes, Robert B. T2 - HEALTH PHYSICS AB - Abstract Electron paramagnetic resonance was used to study the dosimetric properties of commercial sweeteners (sucrose, saccharin, and stevia). The results concluded that sugar has dosimetric properties of interest, which makes it suitable for dose reconstruction, emergency response, and nuclear forensics applications. The radiation dose response was investigated by irradiating samples up to 10 Gy and found to be linear. The post-irradiation stability of samples was observed to be useful for the intended applications. The results showed that the post-irradiation intensities vary from one sample to another, with the general trend demonstrating a small increase in intensities shortly after irradiation followed by an approximately constant leveling out. Finally, the effect of isochronal annealing was studied by heating samples to various temperatures. The results showed an overall stable behavior of the signal below melting temperature. DA - 2022/12// PY - 2022/12// DO - 10.1097/HP.0000000000001614 VL - 123 IS - 6 SP - 476-485 SN - 1538-5159 KW - dosimetry KW - gamma KW - dose assessment KW - gamma radiation KW - radiation dose ER - TY - JOUR TI - Effect of low-temperature annealing on Bi-poor Cs2AgBiBr6 single crystals AU - Cao, Da AU - Yang, Ge T2 - MATERIALS TODAY COMMUNICATIONS AB - All-inorganic double perovskite Cs 2 AgBiBr 6 has attracted increasing research interest due to its great potential for optoelectronic applications. To date, most studies focus on the room-temperature characteristics of as-grown Cs 2 AgBiBr 6 single crystals. In this work, we investigated the effect of low-temperature annealing on the physical properties of Cs 2 AgBiBr 6 single crystals. The studied Cs 2 AgBiBr 6 single crystal was grown using a Bi-poor precursor and has a bandgap of 2.12 eV, showing superior elastic properties with Young’s modulus at 32 GPa and hardness at 1 GPa. When the annealing temperature increased from 25 °C to 80 °C, the resistivity of the as-fabricated Bi-poor Cs 2 AgBiBr 6 crystal decreased from 8.07×10 9 Ω cm to 5.86×10 7 Ω cm. Interestingly, the room-temperature resistivity of the annealed Cs 2 AgBiBr 6 increased nearly 3 times when compared to the original value before the annealing. After the annealing, the Cs 2 AgBiBr 6 crystal still holds a strong response to radiation sources. The temporal response of the Cs 2 AgBiBr 6 crystal under the 568-nm LED illumination also indicated that the rising time and the decay time are much shorter than the initial values before the annealing. These results demonstrate a robust thermal and air stability of Bi-poor Cs 2 AgBiBr 6 single crystal. An effective annealing strategy could play an important role in tuning the fast decay- and rise-time characteristics of Cs 2 AgBiBr 6 single crystals. • Fabricated Bi-poor Cs 2 AgBiBr 6 single crystals and studied the effect of low-temperature annealing on it. • The resistivity increased nearly 3 times after the annealing temperature up to 80 °C. • The fabricated device showed a strong response to gamma sources and LED illumination of 568 nm before and after annealing. • The response time to LED illumination enhanced a lot after low-temperature annealing. DA - 2022/12// PY - 2022/12// DO - 10.1016/j.mtcomm.2022.104242 VL - 33 SP - SN - 2352-4928 UR - http://dx.doi.org/10.1016/j.mtcomm.2022.104242 KW - Cs2AgBiBr6 KW - Bi-poor KW - Annealing KW - Resistivity KW - Photocurrent KW - Radiation response ER - TY - JOUR TI - COHERENT constraint on leptophobic dark matter using CsI data AU - Akimov, D. AU - An, P. AU - Awe, C. AU - Barbeau, P. S. AU - Becker, B. AU - Belov, V. AU - Bernardi, I. AU - Blackston, M. A. AU - Bock, C. AU - Bolozdynya, A. AU - Bouabid, R. AU - Browning, J. AU - Cabrera-Palmer, B. AU - Chernyak, D. AU - Conley, E. AU - Daughhetee, J. AU - Detwiler, J. AU - Ding, K. AU - Durand, M. R. AU - Efremenko, Y. AU - Elliott, S. R. AU - Fabris, L. AU - Febbraro, M. AU - Rosso, A. Gallo AU - Galindo-Uribarri, A. AU - Green, M. P. AU - Heath, M. R. AU - Hedges, S. AU - Hoang, D. AU - Hughes, M. AU - Johnson, B. A. AU - Johnson, T. AU - Khromov, A. AU - Konovalov, A. AU - Kozlova, E. AU - Kumpan, A. AU - Li, L. AU - Link, J. M. AU - Liu, J. AU - Major, A. AU - Mann, K. AU - Markoff, D. M. AU - Mastroberti, J. AU - Mattingly, J. AU - Mueller, P. E. AU - Newby, J. AU - Parno, D. S. AU - Penttila, S. I. AU - Pershey, D. AU - Prior, C. AU - Rapp, R. AU - Ray, H. AU - Razuvaeva, O. AU - Reyna, D. AU - Rich, G. C. AU - Ross, J. AU - Rudik, D. AU - Runge, J. AU - Salvat, D. J. AU - Salyapongse, A. M. AU - Sander, J. AU - Scholberg, K. AU - Shakirov, A. AU - Simakov, G. AU - Snow, W. M. AU - Sosnovstsev, V. AU - Suh, B. AU - Tayloe, R. AU - Tellez-Giron-Flores, K. AU - Tolstukhin, I. AU - Ujah, E. AU - Vanderwerp, J. AU - Varner, R. L. AU - Virtue, C. J. AU - Visser, G. AU - Wongjirad, T. AU - Yen, Y. -r. AU - Yoo, J. AU - Yu, C. -H. AU - Zettlemoyer, J. T2 - PHYSICAL REVIEW D AB - We use data from the COHERENT CsI[Na] scintillation detector to constrain sub-GeV leptophobic dark matter models. This detector was built to observe low-energy nuclear recoils from coherent elastic neutrino-nucleus scattering. These capabilities enable searches for dark matter particles produced at the Spallation Neutron Source mediated by a vector portal particle with masses between 2 and $400\text{ }\text{ }\mathrm{MeV}/{\mathrm{c}}^{2}$. No evidence for dark matter is observed and a limit on the mediator coupling to quarks is placed. This constraint improves upon previous results by two orders of magnitude. This newly explored parameter space probes the region where the dark matter relic abundance is explained by leptophobic dark matter when the mediator mass is roughly twice the dark matter mass. COHERENT sets the best constraint on leptophobic dark matter at these masses. DA - 2022/9/14/ PY - 2022/9/14/ DO - 10.1103/PhysRevD.106.052004 VL - 106 IS - 5 SP - SN - 2470-0029 ER - TY - JOUR TI - Laser-driven ionization mechanisms of aluminum for single particle aerosol mass spectrometry AU - Lietz, Amanda M. AU - Yee, Benjamin T. AU - Musk II, Jeffrey AU - Moffat, Harry K. AU - Wiemann, Dora K. AU - Settecerri, Taylor AU - Fergenson, David AU - Omana, Michael A. AU - Hopkins, Matthew M. T2 - SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY AB - Single particle aerosol mass spectrometry (SPAMS), an analytical technique for measuring the size and composition of individual micron-scale particles, is capable of analyzing atmospheric pollutants and bioaerosols much more efficiently and with more detail than conventional methods which require the collection of particles onto filters for analysis in the laboratory. Despite SPAMS’ demonstrated capabilities, the primary mechanisms of ionization are not fully understood, which creates challenges in optimizing and interpreting SPAMS signals. In this paper, we present a well-stirred reactor model for the reactions involved with the laser-induced vaporization and ionization of an individual particle. The SPAMS conditions modeled in this paper include a 248 nm laser which is pulsed for 8 ns to vaporize and ionize each particle in vacuum. The ionization of 1 μm, spherical Al particles was studied by approximating them with a 0-dimensional plasma chemistry model. The primary mechanism of absorption of the 248 nm photons was pressure-broadened direct photoexcitation to Al(y2D). Atoms in this highly excited state then undergo superelastic collisions with electrons, heating the electrons and populating the lower energy excited states. We found that the primary ionization mechanism is electron impact ionization of various excited state Al atoms, especially Al(y2D). Because the gas expands rapidly into vacuum, its temperature decreases rapidly. The rate of three-body recombination (e− + e− + Al+ → Al + e−) increases at low temperature, and most of the electrons and ions produced recombine within several μs of the laser pulse. The importance of the direct photoexcitation indicates that the relative peak heights of different elements in SPAMS mass spectra may be sensitive to the available photoexcitation transitions. The effects of laser intensity, particle diameter, and expansion dynamics are also discussed. DA - 2022/11// PY - 2022/11// DO - 10.1016/j.sab.2022.106543 VL - 197 SP - SN - 1873-3565 KW - Aerosol mass spectrometry KW - Plasma modeling KW - Laser-produced plasmas KW - Laser desorption ionization ER - TY - JOUR TI - Quantification of Deep Neural Network Prediction Uncertainties for VVUQ of Machine Learning Models AU - Yaseen, Mahmoud AU - Wu, Xu T2 - NUCLEAR SCIENCE AND ENGINEERING AB - Recent performance breakthroughs in artificial intelligence (AI) and machine learning (ML), especially advances in deep learning, the availability of powerful and easy-to-use ML libraries (e.g., scikit-learn, TensorFlow, PyTorch), and increasing computational power, have led to unprecedented interest in AI/ML among nuclear engineers. For physics-based computational models, verification, validation, and uncertainty quantification (VVUQ) processes have been very widely investigated, and many methodologies have been developed. However, VVUQ of ML models has been relatively less studied, especially in nuclear engineering. This work focuses on uncertainty quantification (UQ) of ML models as a preliminary step of ML VVUQ, more specifically Deep Neural Networks (DNNs) because they are the most widely used supervised ML algorithm for both regression and classification tasks. This work aims at quantifying the prediction or approximation uncertainties of DNNs when they are used as surrogate models for expensive physical models. Three techniques for UQ of DNNs are compared, namely, Monte Carlo Dropout (MCD), Deep Ensembles (DE), and Bayesian Neural Networks (BNNs). Two nuclear engineering examples are used to benchmark these methods: (1) time-dependent fission gas release data using the Bison code and (2) void fraction simulation based on the Boiling Water Reactor Full-size Fine-Mesh Bundle Tests (BFBT) benchmark using the TRACE code. It is found that the three methods typically require different DNN architectures and hyperparameters to optimize their performance. The UQ results also depend on the amount of training data available and the nature of the data. Overall, all three methods can provide reasonable estimations of the approximation uncertainties. The uncertainties are generally smaller when the mean predictions are close to the test data while the BNN methods usually produce larger uncertainties than MCD and DE. DA - 2022/11/4/ PY - 2022/11/4/ DO - 10.1080/00295639.2022.2123203 VL - 11 SP - SN - 1943-748X KW - Uncertainty quantification KW - Deep Neural Network KW - Monte Carlo Dropout KW - Deep Ensemble KW - Bayesian Neural Network ER - TY - JOUR TI - Ion thermal transport in the H-mode edge transport barrier on DIII-D AU - Haskey, S. R. AU - Ashourvan, Arash AU - Banerjee, S. AU - Barada, K. AU - Belli, E. A. AU - Bortolon, A. AU - Candy, J. AU - Chen, J. AU - Chrystal, C. AU - Grierson, B. A. AU - Groebner, R. J. AU - Laggner, F. M. AU - Knolker, M. AU - Kramer, G. J. AU - Major, M. R. AU - Mckee, G. AU - Staebler, G. M. AU - Yan, Z. AU - Zeeland, M. A. Van T2 - Physics of Plasmas AB - The power balance ion heat flux in the pedestal region on DIII-D increases and becomes increasingly anomalous (above conventional neoclassical) in experiments with higher temperature and lower density pedestals where the ion collisionality (νi*) is lowered toward values expected on ITER. Direct measurements of the main-ion temperature are shown to be essential on DIII-D when calculating the ion heat flux due to differences between the temperature of D+ and the more commonly measured C6+ impurity ions approaching the separatrix. Neoclassical transport calculations from NEO and non-linear gyrokinetic calculations using CGYRO are consistent with these observations and show that while neoclassical transport plays an important role, the turbulent ion heat flux due to ion scale electrostatic turbulence is significant and can contribute similar or larger ion heat fluxes at lower collisionality. Beam emission spectroscopy and Doppler backscattering measurements in the steep gradient region of the H-mode pedestal reveal increased broadband, long-wavelength ion scale fluctuations for the low νi* discharges at the radius where the non-linear CGYRO simulations were run. Taken together, increased fluctuations, power balance calculations, and gyrokinetic simulations show that the above neoclassical ion heat fluxes, including the increases at lower νi*, are likely due to weakly suppressed ion scale electrostatic turbulence. These new results are based on world first inferred ion and electron heat fluxes in the pedestal region of deuterium plasmas using direct measurements of the deuterium temperature for power balance across ion collisionalities covering an order of magnitude from high νi* values of 1.3 down to ITER relevant νi* ∼0.1. DA - 2022/1// PY - 2022/1// DO - 10.1063/5.0072155 VL - 29 IS - 1 SP - 012506 UR - http://dx.doi.org/10.1063/5.0072155 ER - TY - JOUR TI - Robust identification of multiple-input single-output system response for efficient pickup noise removal from tokamak diagnostics AU - Odstrcil, T. AU - Laggner, F. M. AU - Rosenthal, A. M. AU - Bortolon, A. AU - Hughes, J. W. AU - Spendlove, J. C. AU - Wilks, T. M. T2 - Review of Scientific Instruments AB - Electromagnetic pickup noise in the tokamak environment imposes an imminent challenge for measuring weak diagnostic photocurrents in the nA range. The diagnostic signal can be contaminated by an unknown mixture of crosstalk signals from coils powered by currents in the kA range. To address this issue, an algorithm for robust identification of linear multi-input single-output (MISO) systems has been developed. The MISO model describes the dynamic relationship between measured signals from power sources and observed signals in the diagnostic and allows for a precise subtraction of the noise component. The proposed method was tested on experimental diagnostic data from the DIII-D tokamak, and it has reduced noise by up to 20 dB in the 1-20 kHz range. DA - 2022/10/1/ PY - 2022/10/1/ DO - 10.1063/5.0100988 UR - https://doi.org/10.1063/5.0100988 ER - TY - JOUR TI - Improved Particle Confinement with Resonant Magnetic Perturbations in DIII-D Tokamak H-Mode Plasmas AU - Logan, N. C. AU - Hu, Q. AU - Paz-Soldan, C. AU - Nazikian, R. AU - Rhodes, T. AU - Wilks, T. AU - Munaretto, S. AU - Bortolon, A. AU - Laggner, F. AU - Scotti, F. AU - Hong, R. AU - Wang, H. T2 - Physical Review Letters AB - Experiments on the DIII-D tokamak have identified a novel regime in which applied resonant magnetic perturbations (RMPs) increase the particle confinement and overall performance. This Letter details a robust range of counter-current rotation over which RMPs cause this density pump-in effect for high confinement (H mode) plasmas. The pump in is shown to be caused by a reduction of the turbulent transport and to be correlated with a change in the sign of the induced neoclassical transport. This novel reversal of the RMP induced transport has the potential to significantly improve reactor relevant, three-dimensional magnetic confinement scenarios. DA - 2022/11/10/ PY - 2022/11/10/ DO - 10.1103/PhysRevLett.129.205001 UR - https://doi.org/10.1103/PhysRevLett.129.205001 ER - TY - JOUR TI - Details of the neutral energy distribution and ionization source using spectrally resolved Balmer-alpha measurements on DIII-D AU - Haskey, S. R. AU - Grierson, B. A. AU - Stagner, L. AU - Chrystal, C. AU - Bortolon, A. AU - Laggner, F. M. T2 - Review of Scientific Instruments AB - Spectrally resolved passive Balmer-α (D-α, H-α) measurements from the DIII-D 16 channel edge main-ion charge exchange recombination system confirm the presence of higher energy neutrals ("thermal" neutrals) in addition to the cold neutrals that recycle off the walls in the edge region of DIII-D plasmas. Charge exchange between thermal ions and edge neutrals transfers energy and momentum between the populations giving rise to thermal neutrals with energies approximating the ions in the pedestal region. Multiple charge exchange events in succession allow an electron to effectively take a random walk, transferring from ion to ion, providing a pathway of increasing energy and velocity, permitting a neutral to get deeper into the plasma before a final ionization event that contributes to the ion and electron particle fueling. Spectrally resolved measurements provide information about the density and velocity distribution of these neutrals, which has been historically valuable for validating Monte Carlo neutral models, which include the multi stage charge exchange dynamics. Here, a multi-channel set of such measurements is used to specifically isolate the details of the thermal neutrals that are responsible for fueling inside the pedestal top. Being able to separate the thermal from the cold emission overcomes several challenges associated with optical filter-based neutral density measurements. The neutral dynamics, deeper fueling by the thermal neutrals, and spectral measurement are modeled with the FIDASIM Monte Carlo collisional radiative code, which also produces synthetic spectra with a shape that is in close agreement with the measurements. By scaling the number of neutrals in the simulation to match the intensity of the thermal emission, we show it is possible to obtain local neutral densities and ionization source rates. DA - 2022/10/1/ PY - 2022/10/1/ DO - 10.1063/5.0101854 UR - https://doi.org/10.1063/5.0101854 ER - TY - JOUR TI - Local measurements of the pedestal magnetic field profile throughout the ELM cycle on DIII-D AU - Burke, M. G. AU - Fonck, R. J. AU - McKee, G. R. AU - Burrell, K. H. AU - Haskey, S. R. AU - Knolker, M. AU - Laggner, F. M. AU - Osborne, T. H. AU - Victor, B. S. AU - Yan, Z. T2 - Physics of Plasmas AB - New high speed localized measurements of the pedestal magnetic field during the edge localized mode (ELM) cycle of a DIII-D High confinement mode (H-mode) discharge indicate a temporally and spatial complex redistribution of the edge current density profile, jedge. The measurement technique extracts the magnetic field magnitude, B, via the spectral separation of Stark-split neutral beam radiation in the pedestal. Single spatial channel measurements from a novel spatial heterodyne spectrometer are validated in discharges with core current profile changes. The technique measures Stark-splitting changes that imply B changes as small as 1 mT with high time resolution (50 μs). At normalized poloidal flux ψn=1.0, B appears saturated in the inter-ELM period and then rapidly decreases in &lt;200 μs by ∼1%, before edge recycling emission begins to increase. Radially inboard of jedge, B increases at the ELM crash. The behavior is consistent with a rapid collapse of jedge at the ELM crash and subsequent pedestal recovery. In some discharges, at ψn&lt;0.96, changes in B are observed throughout the ELM cycle. In others, B recovers and is relatively stable until a few ms leading up to the next crash. Measurements of B during the H-mode transition show a large increase at ψn=1 with little change at ψn=0.9, consistent with the formation of the edge bootstrap current density peak. The ψn=0.9 spectrum is complicated by predicted changes to the Stark component intensities with density at the L–H transition. DA - 2022/10// PY - 2022/10// DO - 10.1063/5.0102610 UR - https://doi.org/10.1063/5.0102610 ER - TY - JOUR TI - Design of a Novel Variable Geometry Divertor for Tokamaks AU - Xu, Chongdu AU - Nagy, Alexander AU - Bortolon, Alessandro AU - Shafer, Morgan AU - Laggner, Florian M. T2 - IEEE Transactions on Plasma Science AB - The divertor is a key component of fusion reactors, allowing exhaust of gas, impurities, and helium ash to preserve plasma purity. The divertor geometry strongly affects plasma performance, and it is designed to be compatible with different plasma shapes in present-day fusion experiments. We present a novel concept for a variable geometry divertor, in which the divertor baffle tiles are reorientable by external actuation. Implementation of this concept in a medium-sized research tokamak would uniquely provide the flexibility to tailor divertor geometry to the plasma configuration and also enable study of the effect of divertor closure on plasma performance. To ensure compatibility with typical tokamak operations, the adjustable divertor must withstand the effects of significant mechanical and thermal stresses such as MW/m2-scale heat fluxes and large electromagnetic fields, e.g., disruption forces. The technological solutions for actuation mechanisms, cooling system, gas baffling and plasma-facing components are assessed. A functional reduced-scale model with movable outer divertor target baffle tiles is developed and the actuation mechanism is tested. DA - 2022/9// PY - 2022/9// DO - 10.1109/TPS.2022.3194847 UR - https://doi.org/10.1109/TPS.2022.3194847 KW - Plasmas KW - Tokamaks KW - Geometry KW - Shape KW - Impurities KW - Heating systems KW - Copper KW - Divertor KW - divertor closure KW - gas baffling KW - plasma-facing components KW - tokamak operations KW - variable geometry ER - TY - JOUR TI - Gas-phase oxidation and nanoparticle formation in multi-element laser ablation plumes AU - Kautz, Elizabeth J. AU - Zelenyuk, Alla AU - Gwalani, Bharat AU - Phillips, Mark C. AU - Harilal, Sivanandan S. T2 - PHYSICAL CHEMISTRY CHEMICAL PHYSICS AB - Interaction of a multi-element laser produced plasma with air leads to formation of fractal agglomerates of nanoparticles consisting of multiple elements and their oxides. DA - 2022/10/20/ PY - 2022/10/20/ DO - 10.1039/d2cp02437c VL - 10 SP - SN - 1463-9084 UR - https://doi.org/10.1039/D2CP02437C ER - TY - JOUR TI - Development and assessment of a reactor system prognosis model with physics-guided machine learning AU - Gurgen, Anil AU - Dinh, Nam T. T2 - NUCLEAR ENGINEERING AND DESIGN AB - Autonomous control systems provide recommendations to help operators in decision-making during plant operations ranging from normal operation to accident management. An important step of autonomous control is prognosis. In nuclear engineering domain, prognosis is the process of predicting future conditions of a system or equipment based on present signs and symptoms of a fault. The prognosis model allows predicting future reactor states for possible candidate control strategies so that the outcomes can be evaluated to determine the best control strategy. The prognosis model requires representing direct relationships between the symptoms and the predictions. In nuclear engineering, computational simulations are approximate representations of the operation of the real system. However, prognosis with computational simulations requires high computation power and time due to possible large number of scenarios. Necessary computation resources can be reduced with machine learning (ML) approach for fast predictions by building a surrogate function using the simulation data. A critical issue is, ML models are ignorant of physical knowledge, and these models approximate statistical relationships between the system variables. This ignorance can produce results that are inconsistent with physical laws, even if an optimal result is achieved from a mathematical point of view. Physics-guided machine learning (PGML) is an approach to tackle this issue. This work formulates and illustrates a framework to guide development and assessment of the ML-based prognosis model for autonomous control systems. The development of the prognosis model considers the training of a ML model which consists of optimizing many aspects of the ML approach. The assessment of the prognosis model considers training data limitations and uncertainties of the ML approach. Prognosis models with standalone ML and PGML are developed and assessed on the loss-of-flow scenario of Experimental Breeder Reactor II. The results indicate that PGML based prognosis model has the best performance compared to other prognosis models. DA - 2022/11// PY - 2022/11// DO - 10.1016/j.nucengdes.2022.111976 VL - 398 SP - SN - 1872-759X KW - Nuclear power plant KW - Autonomous control KW - Prognosis KW - Physics-guided machine learning ER - TY - JOUR TI - Neutron activation analysis of novel space shielding for terrestrial applications AU - Long, Michael AU - Hayes, Robert B. T2 - NUCLEAR ENGINEERING AND DESIGN AB - Appropriate disposition of nuclear waste is a high priority in the production of nuclear energy and its minimization is of great interest to the public. Employing the use of metal oxide infused conformal coatings as a shielding material in a terrestrial reactor should ideally produce nuclear wastes no higher than class B while also reducing the neutron activations (and thus waste classification) of any materials behind the shield. This allows for the increased likelihood of the ability to use on-site sequestration or minimal near-surface disposal, in lieu of geological repositories, and thus the potential for considerable cost savings. DA - 2022/11// PY - 2022/11// DO - 10.1016/j.nucengdes.2022.111989 VL - 398 SP - SN - 1872-759X KW - Metal oxide KW - Conformal coating KW - Activation analysis KW - Radiological waste KW - Nuclear waste KW - Waste disposal ER - TY - JOUR TI - Direct Numerical Simulation of Low and Unitary Prandtl Number Fluids in Reactor Downcomer Geometry AU - Tai, C.-K. AU - Nguyen, T. AU - Iskhakov, A.S. AU - Merzari, E. AU - Dinh, N. AU - Bolotnov, I.A. T2 - arXiv DA - 2022/// PY - 2022/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85128839982&partnerID=MN8TOARS ER - TY - JOUR TI - Data-driven Hi2Lo for Coarse-grid System Thermal Hydraulic Modeling AU - Iskhakov, A.S. AU - Dinh, N.T. AU - Leite, V.C. AU - Merzari, E. T2 - arXiv DA - 2022/// PY - 2022/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85126815096&partnerID=MN8TOARS ER - TY - JOUR TI - Analyzing the effect of pressure on the properties of point defects in gamma U-Mo through atomistic simulations AU - Beeler, Benjamin AU - Zhang, Yongfeng AU - Hasan, A. T. M. Jahid AU - Park, Gyuchul AU - Hu, Shenyang AU - Mei, Zhi-Gang T2 - MRS ADVANCES AB - Uranium–molybdenum (U–Mo) alloys in monolithic fuel foil are the primary candidate for the conversion of high-performance research reactors in the USA. Monolithic fuel is utilized in a plate-type design with a zirconium diffusion barrier and aluminum cladding. These fuel types are unique in that they contain no plenum for the release of fission gases, which, in conjunction with the aluminum cladding, can lead to large stress states within the fuel. The nature of how fundamental processes of radiation damage, including the evolution of point defects, under such stresses occur is unknown. In this work, we present molecular dynamics simulations of the formation energy of point defects under applied stress. This work will allow for the implementation of stress-dependent microstructural evolution models of nuclear fuels, including those for both fission gas bubble growth and creep, which are critical to ensure the stable and predictable behavior of research reactor fuels. DA - 2022/10/13/ PY - 2022/10/13/ DO - 10.1557/s43580-022-00350-y VL - 10 SP - SN - 2059-8521 UR - https://doi.org/10.1557/s43580-022-00350-y ER - TY - JOUR TI - Development and assessment of prognosis digital twin in a NAMAC system AU - Lin, Linyu AU - Gurgen, Anil AU - Dinh, Nam T2 - ANNALS OF NUCLEAR ENERGY AB - The nearly autonomous management and control (NAMAC) system is a comprehensive control system to assist plant operations by furnishing control recommendations to operators. Prognosis digital twin (DT-P) is a critical component in NAMAC for predicting action effects and supporting NAMAC decision-making during normal and accident scenarios. To quantifying and reducing uncertainty of machine-learning-based DT-Ps in multi-step predictions, this work investigates and derives insights from the application of three techniques for optimizing the performance of DT-P by long short-term memory recurrent neural networks, including manual search, sequential model-based optimization, and physics-guided machine learning. Sequential model-based optimization and physics-guide machine learning result in smallest errors when the predicting transients are similar to the training data. DA - 2022/12/15/ PY - 2022/12/15/ DO - 10.1016/j.anucene.2022.109439 VL - 179 SP - SN - 1873-2100 KW - Digital twin KW - Prognosis KW - Machine learning KW - Autonomous control ER - TY - JOUR TI - Spark plasma sintered, MoNbTi-based multi-principal element alloys with Cr, V, and Zr AU - Beausoleil Ii, G. L. AU - Parry, M. E. AU - Mondal, K. AU - Kwon, S. AU - Gomez-Hurtado, L. R. AU - Kaoumi, D. AU - Aguiar, J. A. T2 - JOURNAL OF ALLOYS AND COMPOUNDS AB - MoNbTi, MoNbTiZr, CrMoNbTiZr, and MoNbTiVZr multi-principal element alloys (MPEAs) were fabricated via spark plasma sintering (SPS) and investigated for use in high-strength applications. The fabrication method by SPS and powder metallurgy differs from those presented in the prior literature, where most MPEAs are fabricated using arc melting (AM) methods. Cryogenic milling was used to maximize potential defect sinks (grain boundaries) for radiation resistance and to increase ultimate tensile strength through the Hall-Petch effect. SPS was chosen for consolidation in order to maintain a fine-grained structure during densification. Each alloy was characterized using x-ray diffraction and scanning electron microscopy for phase identification and compositional homogeneity. The base ternary alloy MoNbTi presented a predominantly single BCC system with minor cubic phases. The introduction of additional alloying elements—Zr, V, and Cr—heightened the phase complexity and increased the fractions of a secondary BCC phase and an HCP phase from Zr. The addition of Cr induced a larger fraction of the Laves phase to form. The addition of V caused the precipitation of small Mo inclusions. Thermodynamic analysis was performed to understand the separation of phases in each alloy. Discrepancies among the phase predictions generated by thermodynamic models, phases previously presented in the literature, and the characterization results suggest that MPEA fabrication methods, especially solid-state methods, require significant investigation to ensure that alloys can remain stable throughout their anticipated service lifetimes. DA - 2022/12/15/ PY - 2022/12/15/ DO - 10.1016/j.jallcom.2022.167083 VL - 927 SP - SN - 1873-4669 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85138797103&partnerID=MN8TOARS KW - High-entropy alloy KW - Multi-principal element alloys KW - Nuclear materials KW - High-temperature alloys KW - Refractory alloys ER - TY - JOUR TI - Electric discharge initiation in water with gas bubbles: A time scale approach AU - Sponsel, Nicholas L. AU - Gershman, Sophia AU - Quesada, Maria J. Herrera J. AU - Mast, Jacob T. AU - Stapelmann, Katharina T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - High voltage nanosecond pulse driven electric discharges in de-ionized water with an argon bubble suspended between two electrodes were experimentally investigated. Two electrode configurations were used to temporally resolve the time scales of the discharge from the applied voltage rise time (7 ns), through the end of the first pulse (∼30 ns), and longer (&gt;50 ns). We found that, in positive and negative applied voltage polarities, discharge initiates in the water at the tip of the anode. The discharge in the water rapidly extends (∼104 m/s) to the apex of the bubble and light emitted from inside the bubble begins to form. The steep rate of rise of the applied voltage (dV/dt&lt;4 kV/ns) and the short time for the development of discharge in the water suggest that cavitation is a likely mechanism for discharge initiation and propagation in water. In addition, the short duration of the applied voltage pulse results in only a partial Townsend discharge inside the bubble. DA - 2022/12// PY - 2022/12// DO - 10.1116/6.0001990 VL - 40 IS - 6 SP - SN - 1520-8559 UR - https://doi.org/10.1116/6.0001990 ER - TY - JOUR TI - Plasma breakdown in bubbles passing between two pin electrodes AU - Pillai, Naveen AU - Sponsel, Nicholas L. AU - Mast, J. T. AU - Kushner, Mark J. AU - Bolotnov, Igor A. AU - Stapelmann, Katharina T2 - JOURNAL OF PHYSICS D-APPLIED PHYSICS AB - Abstract The ignition of plasmas in liquids has applications from medical instrumentation to manipulation of liquid chemistry. Formation of plasmas directly in a liquid often requires prohibitively large voltages to initiate breakdown. Producing plasma streamers in bubbles submerged in a liquid with higher permittivity can significantly lower the voltage needed to initiate a discharge by reducing the electric field required to produce breakdown. The proximity of the bubble to the electrodes and the shape of the bubbles play critical roles in the manner in which the plasma is produced in, and propagates through, the bubble. In this paper, we discuss results from a three-dimensional direct numerical simulation (DNS) used to investigate the shapes of bubbles formed by injection of air into water. Comparisons are made to results from a companion experiment. A two-dimensional plasma hydrodynamics model was then used to capture the plasma streamer propagation in the bubble using a static bubble geometry generated by the DNS The simulations showed two different modes for streamer formation depending on the bubble shape. In an elliptical bubble, a short electron avalanche triggered a surface ionization wave (SIWs) resulting in plasma propagating along the surface of the bubble. In a circular bubble, an electron avalanche first traveled through the middle of the bubble before two SIWs began to propagate from the point closest to the grounded electrode where a volumetric streamer intersected the surface. In an elliptical bubble approaching a powered electrode in a pin-to-pin configuration, we experimentally observed streamer behavior that qualitatively corresponds with computational results. Optical emission captured over the lifetime of the streamer curve along the path of deformed bubbles, suggesting propagation of the streamer along the liquid/gas boundary interface. Plasma generation supported by the local field enhancement of the deformed bubble surface boundaries is a mechanism that is likely responsible for initiating streamer formation. DA - 2022/11/24/ PY - 2022/11/24/ DO - 10.1088/1361-6463/ac9538 VL - 55 IS - 47 SP - SN - 1361-6463 UR - https://doi.org/10.1088/1361-6463/ac9538 KW - plasma KW - low-temperature KW - DNS KW - bubbles KW - simulation ER - TY - JOUR TI - Elucidation of divergent desaturation pathways in the formation of vinyl isonitrile and isocyanoacrylate AU - Kim, Wantae AU - Chen, Tzu-Yu AU - Cha, Lide AU - Zhou, Grace AU - Xing, Kristi AU - Canty, Nicholas Koenig AU - Zhang, Yan AU - Chang, Wei-Chen T2 - NATURE COMMUNICATIONS AB - Two different types of desaturations are employed by iron- and 2-oxoglutarate-dependent (Fe/2OG) enzymes to construct vinyl isonitrile and isocyanoacrylate moieties found in isonitrile-containing natural products. A substrate-bound protein structure reveals a plausible strategy to affect desaturation and hints at substrate promiscuity of these enzymes. Analogs are synthesized and used as mechanistic probes to validate structural observations. Instead of proceeding through hydroxylated intermediate as previously proposed, a plausible carbocation species is utilized to trigger C=C bond installation. These Fe/2OG enzymes can also accommodate analogs with opposite chirality and different functional groups including isonitrile-(D)-tyrosine, N-formyl tyrosine, and phloretic acid, while maintaining the reaction selectivity. DA - 2022/9/12/ PY - 2022/9/12/ DO - 10.1038/s41467-022-32870-4 VL - 13 IS - 1 SP - SN - 2041-1723 ER - TY - JOUR TI - CTF: A modernized, production-level, thermal hydraulic solver for the solution of industry-relevant challenge problems in pressurized water reactors AU - Salko, Robert AU - Wysocki, Aaron AU - Blyth, Taylor AU - Toptan, Aysenur AU - Hu, Jianwei AU - Kumar, Vineet AU - Dances, Chris AU - Dawn, William AU - Sung, Yixing AU - Kucukboyaci, Vefa AU - Gurecky, William AU - Lange, Travis AU - Zhao, Xingang AU - Rader, Jordan AU - Jernigan, Caleb AU - Collins, Benjamin AU - Avramova, Maria AU - Magedanz, Jeffrey AU - Palmtag, Scott AU - Clarno, Kevin AU - Kropaczek, Dave AU - Hizoum, Belgacem AU - Godfrey, Andrew AU - Pointer, Dave AU - Turner, John AU - Sankaran, Ramanan AU - Schmidt, Rod AU - Hooper, Russell AU - Bartlett, Roscoe AU - Baird, Mark AU - Pilch, Martin T2 - NUCLEAR ENGINEERING AND DESIGN AB - CTF is a thermal hydraulic (T/H) subchannel tool that has been extensively developed over the past ten years as part of the Consortium for Advanced Simulation of Light Water Reactors (CASL) program. The code was selected early in the CASL program for support of high-impact challenge problems that were found to be relevant to the nuclear industry and its currently operating fleet of pressurized water reactors (PWRs), including issues such as departure from nucleate boiling (DNB), crud-induced power shifts (CIPSs), and reactivity-insertion accidents (RIAs). By incorporating CTF into the multiphysics Virtual Environment for Reactor Application (VERA) core simulator software developed by CASL, CTF has become the primary means of providing fluid and fuel thermal feedback, as well as T/H figure-of-merits (FOMs) in large-scale reactor simulations. With the goal of solving industry challenge problems, CASL placed great emphasis on developing high-quality, high-performance, validated software tools that offer higher fidelity than what is currently possible with current industry methods. In support of this effort, CTF was developed from a research tool into an nuclear quality assurance (NQA-1)–compliant, production-level software tool that is capable of addressing the stated challenge problems and goals of CASL. This paper presents a review of the major technological achievements that were realized in developing CTF over the past decade of the CASL program and presents an overview of the code solution approach and closure models. DA - 2022/10// PY - 2022/10// DO - 10.1016/j.nucengdes.2022.111927 VL - 397 SP - SN - 1872-759X KW - Subchannel KW - LWR KW - CTF KW - VERA ER - TY - JOUR TI - A Multigroup Homogeneous Flux Reconstruction Method Based on the ANOVA-HDMR Decomposition AU - Bokov, Pavel M. AU - Botes, Danniell AU - Prinsloo, Rian H. AU - Tomasevic, Djordje I T2 - NUCLEAR SCIENCE AND ENGINEERING AB - In this paper, we formulate a new flux reconstruction method based on the High Dimensional Model Representation (HDMR) of the nodal flux shape. The method requires the conventional nodal parameters obtained as a result of the transverse-integration nodal solution procedure as well as corner values calculated by a combination of finite-volume and finite-difference approximations. The proposed flux reconstruction procedure is applicable to rectangular nodes and more than two energy groups. The flux reconstruction method is applied to a number of homogeneous and heterogeneous test problems in order to evaluate its accuracy. DA - 2022/9/11/ PY - 2022/9/11/ DO - 10.1080/00295639.2022.2108654 SP - SN - 1943-748X KW - Flux reconstruction KW - higher-order nodal method KW - transverse-integrated nodal methods KW - ANOVA-HDMR KW - BEAVRS benchmark ER - TY - JOUR TI - A Perspective on Data-Driven Coarse Grid Modeling for System Level Thermal Hydraulics AU - Iskhakov, Arsen S. AU - Tai, Cheng-Kai AU - Bolotnov, Igor A. AU - Dinh, Nam T. T2 - NUCLEAR SCIENCE AND ENGINEERING DA - 2022/9/10/ PY - 2022/9/10/ DO - 10.1080/00295639.2022.2107864 VL - 9 SP - SN - 1943-748X UR - http://dx.doi.org/10.1080/00295639.2022.2107864 KW - Data-driven methods KW - coarse grid modeling KW - system thermal hydraulics KW - machine learning KW - multiscale bridging ER - TY - JOUR TI - Preliminary Siting, Operations, and Transportation Considerations for Licensing Fission Batteries in the United States AU - Lee, DaeHo AU - Diaconeasa, Mihai A. T2 - Eng AB - Nuclear energy is currently in the spotlight as a future energy source all over the world amid the global warming crisis. In the current state of miniaturization, through the development of advanced reactors, such as small modular reactors (SMRs) and micro-reactors, a fission battery is inspired by the idea that nuclear energy can be used by ordinary people using the “plug-and-play” concept, such as chemical batteries. As for design requirements, fission batteries must be economical, standardized, installed, unattended, and reliable. Meanwhile, the commercialization of reactors is regulated by national bodies, such as the United States (U.S.) Nuclear Regulatory Commission (NRC). At an international level, the International Atomic Energy Agency (IAEA) oversees the safe and peaceful use of nuclear power. However, regulations currently face a significant gap in terms of their applicability to advanced non-light water reactors (non-LWRs). Therefore, this study investigates the regulatory gaps in the licensing of fission batteries concerning safety in terms of siting, autonomous operation, and transportation, and suggests response strategies to supplement them. To figure out the applicability of the current licensing framework to fission batteries, we reviewed the U.S. NRC Title 10, Code of Federal Regulations (CFR), and IAEA INSAG-12. To address siting issues, we explored the non-power reactor (NPR) approach for site restrictions and the permit-by-rule (PBR) approach for excessive time burdens. In addition, we discussed how the development of an advanced human-system interface augmented with artificial intelligence and monitored by personnel for fission batteries may enable successful exemptions from the current regulatory operation staffing requirements. Finally, we discovered that no transportation regulatory challenge exists. DA - 2022/9/4/ PY - 2022/9/4/ DO - 10.3390/eng3030027 UR - https://doi.org/10.3390/eng3030027 ER - TY - JOUR TI - Comparison of glancing-angle scatterings on different materials in a high aspect ratio plasma etching process using molecular dynamics simulation AU - Du, Yao AU - Kruger, Florian AU - Nam, Sang Ki AU - Lee, Hoki AU - Yoo, Suyoung AU - Eapen, Jacob AU - Kushner, Mark J. AU - Shannon, Steven T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - In plasma etching for microelectronics fabrication, one of the objectives is to produce a high aspect ratio (HAR) via and trench structures. A principal contributor to the HAR feature shape is the manner in which energetic ions interact with sidewalls inside the feature. The scattering angle and energy loss of ions reflecting from sidewalls determine the sidewall slope and can lead to defects such as microtrenching and bowing. Understanding how ions interact with sidewalls can improve our control of the critical dimensions of HAR features. Ions accelerated in the plasma sheath arrive in the feature with energies as large as a few keV and initially strike the sidewalls at glancing angles. These scattering events extend to the photolithographic mask. Scattering from the mask at glancing angles can produce ions incident into the underlying feature with a broader angular distribution, leading to less desirable feature properties. In this work, results are discussed from Molecular Dynamics (MD) simulations of glancing-angle scattering of argon ions from three materials common to HAR etch: polystyrene (as a photoresist surrogate), amorphous carbon (a hard mask material), and SiO2 (a common insulating material used in microelectronics devices). Results from simulations reveal a transition from specular scattering to diffuse scattering as the angle of the incident ion decreases (90° being glancing incidence) and incident energy increases. Scattering from polystyrene is more diffuse compared to amorphous carbon and SiO2 for identical incident ion conditions. DA - 2022/9// PY - 2022/9// DO - 10.1116/6.0002008 VL - 40 IS - 5 SP - SN - 1520-8559 UR - https://doi.org/10.1116/6.0002008 ER - TY - JOUR TI - Laser Powder Bed Fusion of ODS 14YWT from Gas Atomization Reaction Synthesis Precursor Powders AU - Saptarshi, Sourabh AU - DeJong, Matthew AU - Rock, Christopher AU - Anderson, Iver AU - Napolitano, Ralph AU - Forrester, Jennifer AU - Lapidus, Saul AU - Kaoumi, Djamel AU - Horn, Timothy T2 - JOM AB - Abstract Laser powder bed fusion (LPBF) additive manufacturing (AM) is a promising route for the fabrication of oxide dispersion strengthened (ODS) steels. In this study, 14YWT ferritic steel powders were produced by gas atomization reaction synthesis (GARS). The rapid solidification resulted in the formation of stable, Y-containing intermetallic Y 2 Fe 17 on the interior of the powder and a stable Cr-rich oxide surface. The GARS powders were consolidated with LPBF. Process parameter maps identified a stable process window resulting in a relative density of 99.8%. Transmission electron microscopy and high-energy x-ray diffraction demonstrated that during LPBF, the stable phases in the powder dissociated in the liquid melt pool and reacted to form a high density (1.7 × 10 20 /m 3 ) of homogeneously distributed Ti 2 Y 2 O 7 pyrochlore dispersoids ranging from 17 to 57 nm. The use of GARS powder bypasses the mechanical alloying step typically required to produce ODS feedstock. Preliminary mechanical tests demonstrated an ultimate tensile and yield strength of 474 MPa and 312 MPa, respectively. DA - 2022/8/2/ PY - 2022/8/2/ DO - 10.1007/s11837-022-05418-6 VL - 8 SP - SN - 1543-1851 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85135355752&partnerID=MN8TOARS ER - TY - JOUR TI - Investigation of heavy metals in cottonseeds with instrumental neutron activation analysis AU - Sun, Zaijing AU - Nangeelil, Krishnakumar Divakar AU - Cai, Qingseng AU - Lassell, Scott T2 - JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY DA - 2022/8/11/ PY - 2022/8/11/ DO - 10.1007/s10967-022-08461-4 SP - SN - 1588-2780 KW - Instrumental Neutron Activation Analysis KW - Heavy Metals KW - Cotton seeds KW - PULSTAR reactor KW - Principal Component Analysis ER - TY - JOUR TI - An adaptive knowledge-based data-driven approach for turbulence modeling using ensemble learning technique under complex flow configuration: 3D PWR sub-channel with DNS data AU - Zhu, Yangmo AU - Dinh, Nam T. AU - Saini, Nadish AU - Bolotnov, Igor A. T2 - NUCLEAR ENGINEERING AND DESIGN AB - This work describes a new approach to increase the accuracy of Reynolds-averaged Navier–Stokes (RANS) in modeling turbulence flow leveraging the machine learning technique. Traditionally, different turbulence models for Reynolds stress are developed for different flow patterns based on human knowledge. Each turbulence model has a certain application domain and prediction uncertainty. In recent years, with the rapid improvements of machine learning techniques, researchers start to develop an approach to compensate for the prediction discrepancy of traditional turbulence models with statistical models and data. However, the approach has deficiencies in several aspects. For example, the amount of human knowledge introduced to the statistical model couldn’t be controlled, which makes the statistical model learn from a very naïve stage and limits its application. In this work, a new approach is developed to address those deficiencies. The new approach uses the “ensemble learning” technique to control the amount of human knowledge introduced into the statistical model. Therefore, the new approach could be adaptive to the multiple application domains. According to the results of case study, the new approach shows higher accuracy than both traditional turbulence models and the previous machine learning approach. DA - 2022/7// PY - 2022/7// DO - 10.1016/j.nucengdes.2022.111814 VL - 393 SP - SN - 1872-759X KW - Ensemble learning KW - Machine learning KW - Turbulence KW - RANS ER - TY - JOUR TI - A multimodal approach to revisiting oxidation defects in Cr2O3 AU - Auguste, R. AU - Chan, H. L. AU - Romanovskaia, E. AU - Qiu, J. AU - Schoell, R. AU - Liedke, M. O. AU - Butterling, M. AU - Hirschmann, E. AU - Attallah, A. G. AU - Wagner, A. AU - Selim, F. A. AU - Kaoumi, D. AU - Uberuaga, B. P. AU - Hosemann, P. AU - Scully, J. R. T2 - NPJ MATERIALS DEGRADATION AB - Abstract The oxidation of chromium in air at 700 °C was investigated with a focus on point defect behavior and transport during oxide layer growth. A comprehensive set of characterization techniques targeted characteristics of chromium oxide microstructure and chemical composition analysis. TEM showed that the oxide was thicker with longer oxidation times and that, for the thicker oxides, voids formed at the metal/oxide interface. PAS revealed that the longer the oxidation time, there was an overall reduction in vacancy-type defects, though chromium monovacancies were not found in either case. EIS found that the longer oxidized material was more electrochemically stable and that, while all oxides displayed p-type character, the thicker oxide had an overall lower charge carrier density. Together, the results suggest anion oxygen interstitials and chromium vacancy cluster complexes drive transport in an oxidizing environment at this temperature, providing invaluable insight into the mechanisms that regulate corrosion. DA - 2022/7/26/ PY - 2022/7/26/ DO - 10.1038/s41529-022-00269-7 VL - 6 IS - 1 SP - SN - 2397-2106 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85134822843&partnerID=MN8TOARS ER - TY - JOUR TI - Synthesis of Nano-Oxide Precipitates by Implantation of Ti, Y and O Ions in Fe-10%Cr: Towards an Understanding of Precipitation in Oxide Dispersion-Strengthened (ODS) Steels AU - Jublot-Leclerc, Stephanie AU - Owusu-Mensah, Martin AU - Borodin, Vladimir A. AU - Ribis, Joel AU - Largeau, Ludovic AU - Schoell, Ryan AU - Kaoumi, Djamel AU - Descoins, Marion AU - Mangelinck, Dominique AU - Gentils, Aurelie T2 - MATERIALS AB - The properties of oxide dispersion-strengthened steels are highly dependent on the nature and size distribution of their constituting nano-oxide precipitates. A fine control of the processes of synthesis would enable the optimization of pertinent properties for use in various energy systems. This control, however, requires knowledge of the precise mechanisms of nucleation and growth of the nanoprecipitates, which are still a matter of debate. In the present study, nano-oxide precipitates were produced via the implantation of Y, Ti, and O ions in two different sequential orders in an Fe-10%Cr matrix that was subsequently thermally annealed. The results show that the oxides that precipitate are not necessarily favoured thermodynamically, but rather result from complex kinetics aspects related to the interaction between the implanted elements and induced defects. When Y is implanted first, the formation of nanoprecipitates with characteristics similar to those in conventionally produced ODS steels, especially with a core/shell structure, is evidenced. In contrast, when implantation starts with Ti, the precipitation of yttria during subsequent high-temperature annealing is totally suppressed, and corundum Cr2O3 precipitates instead. Moreover, the systematic involvement of {110} matrix planes in orientation relationships with the precipitates, independently of the precipitate nature, suggests matrix restriction effects on the early stages of precipitation. DA - 2022/7// PY - 2022/7// DO - 10.3390/ma15144857 VL - 15 IS - 14 SP - SN - 1996-1944 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85137262989&partnerID=MN8TOARS KW - ion beam synthesis (IBS) KW - ODS steels KW - ion implantation KW - FeCr KW - nano-oxide precipitates KW - precipitation KW - Y2O3 KW - Cr2O3 KW - Y2Ti2O7 KW - core KW - shell structure ER - TY - JOUR TI - Selected papers from the 2020 International Topical Meeting on Advances in Thermal Hydraulics (ATH'20) Foreword AU - Bolotnov, Igor AU - Benhamadouche, Sofiane T2 - NUCLEAR TECHNOLOGY DA - 2022/8/3/ PY - 2022/8/3/ DO - 10.1080/00295450.2022.2086385 VL - 208 IS - 8 SP - III-III SN - 1943-7471 ER - TY - JOUR TI - Mechanism of chlorine-induced stress corrosion cracking of two 304 SS heats in simulated marine environment through in situ X-ray tomography and diffraction: Role of deformation induced martensite and crack branching AU - Schoell, Ryan AU - Xi, Li AU - Zhao, Yuchen AU - Wu, Xin AU - Hong, Yu AU - Yu, Zhenzhen AU - Kenesei, Peter AU - Almer, Jonathan AU - Shayer, Zeev AU - Kaoumi, Djamel T2 - MATERIALS CHARACTERIZATION AB - In-situ synchrotron x-ray tomography and diffraction experiments were conducted on two heats of 304SS undergoing chlorine-induced stress-corrosion-cracking (CISCC) in a simulated marine environment. The role of deformation induced martensite on CISCC was investigated through diffraction analysis where no significant amount of martensite was found to form during CISCC, indicating that it may not play a significant role in affecting the process. Tomography combined with stress-intensity analysis revealed the influence of stress-intensity on branching types with single crack growth, micro-branching, and macro-branching. Post experimental electron microscopy characterization revealed the presence of FeCl2, CrCl2, and NiCl2·6H2O compounds at the crack, which infers a dissolution mechanism during the experiment. A dissolution mechanism highlighting the synergy between stress and corrosion was proposed to explain chlorine-induced stress-corrosion-cracking and crack branching. DA - 2022/8// PY - 2022/8// DO - 10.1016/j.matchar.2022.112020 VL - 190 SP - SN - 1873-4189 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85132337921&partnerID=MN8TOARS KW - Stress corrosion cracking KW - In-situ KW - Synchrotron X-ray tomography ER - TY - JOUR TI - An ab initio molecular dynamics investigation of the thermophysical properties of molten NaCl-MgCl2 AU - Duemmler, Kai AU - Woods, Michael AU - Karlsson, Toni AU - Gakhar, Ruchi AU - Beeler, Benjamin T2 - JOURNAL OF NUCLEAR MATERIALS AB - Molten salts have many applications in the nuclear and solar energy industries for thermal storage and heat transfer applications. However, there is a knowledge gap in molten salt thermophysical properties which hinders the technical readiness level of molten salt applications, especially in the nuclear industry. A common method of investigating new materials is through ab initio Molecular Dynamics (AIMD) simulations which is an effective tool to investigate structural and thermophysical properties at realistic temperatures. NaCl-MgCl2 is an inexpensive salt that is a good candidate for use as a heat transfer medium in solar power applications or in the secondary loop of a nuclear reactor. In this article, the thermophysical properties of NaCl-MgCl2 are computed via AIMD calculations to supplement the limited experimental studies in the literature. A wide range of compositions and temperatures for the pseudo-binary NaCl-MgCl2 were used to calculate the density, heat capacity, compressibility, enthalpy of mixing, and volumetric thermal expansion coefficient. AIMD is shown to accurately model the densities of molten NaCl-MgCl2 as there is good agreement with the available literature. This work observed a transition to a monotonic increase of the density with respect to MgCl2 composition occurring above 1100 K. The heat capacity values increase uniformly with respect to concentration of MgCl2 at a rate of 2.85 J/mol-K per 10 mol% of MgCl2. Select thermophysical properties are fit to a Redlich-Kister expansion for utilization in multiphysics simulations. DA - 2022/11// PY - 2022/11// DO - 10.1016/j.jnucmat.2022.153916 VL - 570 SP - SN - 1873-4820 UR - https://doi.org/10.1016/j.jnucmat.2022.153916 ER - TY - JOUR TI - CTF-PARCS Core Multi-Physics Computational Framework for Efficient LWR Steady-State, Depletion and Transient Uncertainty Quantification AU - Delipei, Gregory K. AU - Rouxelin, Pascal AU - Abarca, Agustin AU - Hou, Jason AU - Avramova, Maria AU - Ivanov, Kostadin T2 - ENERGIES AB - Best Estimate Plus Uncertainty (BEPU) approaches for nuclear reactor applications have been extensively developed in recent years. The challenge for BEPU approaches is to achieve multi-physics modeling with an acceptable computational cost while preserving a reasonable fidelity of the physics modeled. In this work, we present the core multi-physics computational framework developed for the efficient computation of uncertainties in Light Water Reactor (LWR) simulations. The subchannel thermal-hydraulic code CTF and the nodal expansion neutronic code PARCS are coupled for the multi-physics modeling (CTF-PARCS). The computational framework is discussed in detail from the Polaris lattice calculations up to the CTF-PARCS coupling approaches. Sampler is used to perturb the multi-group microscopic cross-sections, fission yields and manufacturing parameters, while Dakota is used to sample the CTF input parameters and the boundary conditions. Python scripts were developed to automatize and modularize both pre- and post-processing. The current state of the framework allows the consistent perturbation of inputs across neutronics and thermal-hydraulics modeling. Improvements to the standard thermal-hydraulics modeling for such coupling approaches have been implemented in CTF to allow the usage of 3D burnup distribution, calculation of the radial power and the burnup profile, and the usage of Santamarina effective Doppler temperature. The uncertainty quantification approach allows the treatment of both scalar and functional quantities and can estimate correlation between the multi-physics outputs of interest and up to the originally perturbed microscopic cross-sections and yields. The computational framework is applied to three exercises of the LWR Uncertainty Analysis in Modeling Phase III benchmark. The exercises cover steady-state, depletion and transient calculations. The results show that the maximum fuel centerline temperature across all exercises is 2474K with 1.7% uncertainty and that the most correlated inputs are the 238U inelastic and elastic cross-sections above 1 MeV. DA - 2022/7// PY - 2022/7// DO - 10.3390/en15145226 VL - 15 IS - 14 SP - SN - 1996-1073 UR - https://doi.org/10.3390/en15145226 KW - multi-physics KW - CTF KW - PARCS KW - LWR KW - uncertainty quantification ER - TY - JOUR TI - Perovskite materials: from single crystals to radiation detection AU - Kim, Doup AU - Yang, Ge T2 - CRYSTENGCOMM AB - Pb- and Bi-based perovskite materials have high potential for detecting ionizing radiation but an enhanced research effort is needed to achieve large-size, high-performance single crystals at a competitive cost to accelerate this development. DA - 2022/6/29/ PY - 2022/6/29/ DO - 10.1039/d2ce00637e SP - SN - 1466-8033 ER - TY - JOUR TI - Revealing Microstructural, Textural, and Hardness Evolution of Ti-6Al-4V Sheet Cooled From Sub beta-Transus Temperature at Different Rates AU - Chai, Linjiang AU - Xia, Jiying AU - Murty, Korukonda L. AU - Gu, Xinfu AU - Fan, Jiangkun AU - Yao, Zhongwen T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE DA - 2022/6/14/ PY - 2022/6/14/ DO - 10.1007/s11661-022-06737-8 SP - SN - 1543-1940 ER - TY - JOUR TI - Design of Multiple Resonant Reflectance Filter Using One-Dimensional Fibonacci Superconductor Photonic Crystal AU - Athe, Pallavi AU - Athe, Pratik AU - Srivastava, Sanjay AU - Athe, Paridhi AU - Shukla, Surendra Kumar T2 - JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM DA - 2022/6/23/ PY - 2022/6/23/ DO - 10.1007/s10948-022-06318-1 VL - 35 IS - 10 SP - SN - 1557-1947 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85132587348&partnerID=MN8TOARS KW - Superconductor Photonic Crystals KW - Quasiperiodic crystal KW - Transfer matrix method ER - TY - JOUR TI - High Temperature Deformation Behavior of a Fe-25Ni-20Cr (Wt Pct) Austenitic Stainless Steel AU - Alomari, Abdullah S. AU - Kumar, N. AU - Hawary, Mahmoud AU - Murty, K. L. T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE DA - 2022/6/14/ PY - 2022/6/14/ DO - 10.1007/s11661-022-06739-6 VL - 6 SP - SN - 1543-1940 ER - TY - JOUR TI - Advanced CNC/PEG/PDMAA Semi-IPN Hydrogel for Drug Delivery Management in Wound Healing AU - Afrin, Samia AU - Shahruzzaman AU - Haque, Papia AU - Islam, Sazedul AU - Hossain, Shafiul AU - Rashid, Taslim Ur AU - Ahmed, Tanvir AU - Takafuji, Makoto AU - Rahman, Mohammed Mizanur T2 - GELS AB - A Semi Interpenetrating Polymer Network (semi-IPN) hydrogel was prepared and loaded with an antibiotic drug, gentamicin, to investigate the wound healing activity of this system. The semi-IPN hydrogel was synthesized by combining natural polymer cellulose nanocrystal (CNC) and synthetic polymer polyethylene glycol (PEG) and poly (N,N′-dimethyl acrylamide) (PDMAA), which was initially added as a monomer dimethyl acrylamide (DMAA). CNC was prepared from locally obtained jute fibers, dispersed in a PEG-NaOH solvent system and then mixed with monomer DMAA, where polymerization was initiated by an initiator potassium persulphate (KPS) and cross-linked by N,N′-methylenebisacrylamide (NMBA). The size, morphology, biocompatibility, antimicrobial activity, thermal and swelling properties of the hydrogel were investigated by different characterization techniques. The biocompatibility of the hydrogel was confirmed by cytotoxicity analysis, which showed >95% survival of the BHK-21, Vero cell line. The drug loaded hydrogel showed antimicrobial property by forming 25 and 23 mm zone of inhibition against Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria, respectively, in antimicrobial analysis. At pH 5.5, 76% of the drug was released from the hydrogel within 72 h, as observed in an in vitro drug release profile. In an in vivo test, the healing efficiency of the drug loaded hydrogel was examined on a mice model with dorsal wounds. Complete healing of the wound without any scar formation was achieved in 12 days, which revealed excellent wound healing properties of the prepared drug loaded semi-IPN hydrogel. These results showed the relevance of such a system in the rapid healing of acute wounds. DA - 2022/6// PY - 2022/6// DO - 10.3390/gels8060340 VL - 8 IS - 6 SP - SN - 2310-2861 KW - semi-IPN KW - hydrogel KW - drug delivery KW - wound healing ER - TY - JOUR TI - An assessment of protective coating dry cask canisters with structurally amorphous metals (SAMs) for enhanced radiation shielding AU - Alsmadi, Zeinab Y. AU - Bourham, Mohamed A. T2 - NUCLEAR ENGINEERING AND DESIGN AB - The shielding properties of the most common structurally amorphous metals (SAMs) as coating barriers for radiation shielding and corrosion have been computationally studied, for possible use on spent fuel dry cask canisters applications, using the Microshield computational simulation package. The results revealed that SAM1651 exhibited the highest attenuation coefficients and lowest exposure rates at low photon energies, which is attributed to its high elemental content of molybdenum (Mo) and yttrium (Y), while SAM2X5 exhibited the highest attenuation coefficients and lowest exposure rates at high photon energies, due to its high density (7.6 g/cm3) and its elemental content of manganese (Mn), tungsten (W) and silicon (Si). The third SAM material known as SAM 40 had the highest iron content (52.3%), but the results were close to the SAM2X5 as other components were similar, however, SAM2X5 was of higher density. The mean-free path (MFP) and half-value layer (HVL) were very similar for all the three tested SAM materials. DA - 2022/3// PY - 2022/3// DO - 10.1016/j.nucengdes.2022.111647 VL - 388 SP - SN - 1872-759X UR - http://dx.doi.org/10.1016/j.nucengdes.2022.111647 KW - Spent fuel storage systems KW - Amorphous KW - SAMs KW - Computational KW - Attenuation coefficients KW - Exposure rates ER - TY - JOUR TI - Computational Investigation of Beryllium and Lithium Performance in Future Fusion Tokamaks AU - Elbasha, N. M. AU - Bourham, M. A. AU - Mohamed, B. F. T2 - New Energy Exploitation and Application AB - Low-z materials are exemplary candidates in tiling critical plasma-facing components in future fusion reactors due to their low ablation rates under intense high heat fluxes especially during abnormal and hard disruption events. Beryllium and Lithium as low-z materials show good performance as plasma-facing materials in current tokamak. Future tokamaks will exhibit long duration hard disruptions, which in turn requires further investigation of plasma-facing materials, as Li and Be, to judge their performance and evaluate their erosion rates. Electrothermal plasma capillary discharges are used to simulate the high-heat flux deposition on materials to assess their erosion rates. The electrothermal plasma code ETFLOW, which is written for capillary discharges to predict the plasma parameters and erosion rates is used to simulate the high-heat flux conditions similar to expected disruption events for simulated heat fluxes from as low as ~50 to as high as ~290 GW/m2 with a reconnoitering of generating the Be and Li plasmas up to the third ionization (Br+++, Li+++). Performance of Be and Li under the lowest capillary discharge currents (50 kA and 100 kA) is almost identical, however, Li shows sharper increase in the plasma pressure, heat flux, total ablated mass and the exit velocities than Be for higher discharge currents (150, 200 and 250 kA). This huge difference between the performance of Li and Be under low and high heat fluxes can be an important issue for the future magnetic fusion reactors. DA - 2022/1/6/ PY - 2022/1/6/ DO - 10.54963/neea.v1i1.17 VL - 1 IS - 1 J2 - new n.a. exploit. and appl. OP - SN - 2754-5652 UR - http://dx.doi.org/10.54963/neea.v1i1.17 DB - Crossref ER - TY - JOUR TI - Stress-Controlled Creep-Fatigue of an Advanced Austenitic Stainless Steel at Elevated Temperatures AU - Alsmadi, Zeinab Y. AU - Abouelella, Hamdy AU - Alomari, Abdullah S. AU - Murty, K. L. T2 - MATERIALS AB - Creep-fatigue interaction occurs in many structural components of high-temperature systems operating under cyclic and steady-state service conditions, such as in nuclear power plants, aerospace, naval, and other industrial applications. Thus, understanding micromechanisms governing high-temperature creep-fatigue behavior is essential for safety and design considerations. In this work, stress-controlled creep-fatigue tests of advanced austenitic stainless steel (Alloy 709) were performed at a 400 MPa stress range and 750 °C with tensile hold times of 0, 60, 600, 1800, and 3600 s, followed by microstructural examinations. The creep-fatigue lifetime of the Alloy 709 was found to decrease with increasing hold time until reaching a saturation level where the number of cycles to failure did not exhibit a significant decrease. Softening behavior was observed at the beginning of the test, possibly due to the recovery of entangled dislocations and de-twining. In addition, hysteresis loops showed ratcheting behavior, although the mean stress was zero during creep-fatigue cycling, which was attributed to activity of partial dislocations. Microstructural examination of the fracture surfaces showed that fatigue failure dominated at small hold times where the cracks initiated at the surface of the sample. Larger creep cracks were found for longer hold times with a lower probability of dimpled cavities, indicating the dominance of creep deformation. The results were compared with other commonly used stainless steels, and plausible reasons for the observed responses were described. DA - 2022/6// PY - 2022/6// DO - 10.3390/ma15113984 VL - 15 IS - 11 SP - SN - 1996-1944 KW - creep-fatigue KW - Alloy 709 KW - stress-controlled KW - softening KW - ratcheting KW - hysteresis loops KW - high-temperature deformation ER - TY - JOUR TI - A theoretical study on the radiation shielding performance of borate and tellurite glasses AU - Alzahrani, Jamila S. AU - Eke, Canel AU - Alrowaili, Z.A. AU - Boukhris, Imed AU - Mutuwong, C. AU - Bourham, Mohamed A. AU - Al-Buriahi, M.S. T2 - Solid State Sciences AB - The study aims to compare radiation shielding properties of borate and tellurite glasses. This paper presents a theoretical study on the radiation shielding properties of borate and tellurite glasses described by the forms of 80B 2 O 3 –(10-x)Li 2 O–10Na 2 O–xCdO (x is between 0 and 10 mol%) and 64TeO 2 –15ZnO–xBaO–1V 2 O 5 –(20-x)CdO (x is between 0 and 20 mol%), respectively. The radiation shielding properties of both borate and tellurite glasses were assessed applying Monte Carlo simulations via Geant4 platform. The validation of Geant4 simulations was achieved via Phy-X approach. The obtained findings indicate that the mass attenuation coefficients (MACs) for borate and tellurite glasses decline with increment of photon energy reaching their minimum at the regions of high energies (15 MeV) where the pair production is occurred. The maximum half value layer (HVL) of borate glasses are observed at 15 MeV with the values of 18.1991 cm, 17.0473 cm, 15.8572 cm, 14.4132 cm, 12.8305 cm and 12.0506 cm for the CdO content of 0, 2, 4, 6, 8 and 10 mol%, respectively. Therefore, there is a significant effect of CdO on enhancement the shielding ability (reduction of HVL) of borate glasses, and the similar effect is noted for tellurite glasses. Mean free paths (MFPs) of the tellurite glasses are lower than MFPs of the borate glasses for studied energy region. From this result, we can conclude that tellurite glasses have higher photon attenuation properties and thus better shielding material than borate glasses. • Radiation shielding properties of borate and tellurite glasses. • XCOM theoretical calculation. • Geant4 Monte Carlo simulation. • Good agreement between the theory and the simulation. • Significant effect of CdO on the shielding ability of borate and tellurite glasses. DA - 2022/7// PY - 2022/7// DO - 10.1016/j.solidstatesciences.2022.106902 VL - 129 SP - 106902 J2 - Solid State Sciences LA - en OP - SN - 1293-2558 UR - http://dx.doi.org/10.1016/j.solidstatesciences.2022.106902 DB - Crossref KW - Borate glass KW - Tellurite glass KW - Radiation KW - Shielding application ER - TY - JOUR TI - Investigation of the fatigue crack behavior of 304 stainless steels using synchrotron X-ray tomography and diffraction: Influence of the martensite fraction and role of inclusions AU - Schoell, Ryan AU - Xi, Li AU - West, Harvey AU - Hosemann, Peter AU - Park, Jun-Sang AU - Kenesei, Peter AU - Almer, Jonathan AU - Shayer, Zeev AU - Kaoumi, Djamel T2 - MATERIALS CHARACTERIZATION AB - The effect of fatigue on the microstructure of four-point bend specimens of three variations of 304 stainless steels (Commercial 304, 304H, and 304 L) was investigated using synchrotron x-ray tomography and diffraction. X-ray tomography revealed the formation of the fatigue-induced microvoids and crack while the diffraction data was used to quantify the amount of deformation-induced martensite found after fatigue in all samples. Transmission electron microscopy evidenced the role of the precipitates/inclusions on the microvoid formation. It was found to depend on their chemical nature. The shape of the precipitates/inclusions was also found to have an effect on the microvoid shape. DA - 2022/6// PY - 2022/6// DO - 10.1016/j.matchar.2022.111903 VL - 188 SP - SN - 1873-4189 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85129349891&partnerID=MN8TOARS KW - Fatigue KW - 304 stainless steel KW - Synchrotron KW - Tomography KW - Crack propagation ER - TY - JOUR TI - Modeling fission spikes in nuclear fuel using a multigroup model of electronic energy transport AU - Wormald, J. L. AU - Hawari, A. I. T2 - JOURNAL OF NUCLEAR MATERIALS AB - In fission based nuclear reactors the fuel is subject to an intense neutron environment that drives the fission chain reaction. Due to this process fission fragments are created with energies reaching 1 MeV/amu that lose energy primarily through inelastic interactions with the electronic structure producing electronic excitations . Subsequently, these excitations thermalize through electron-phonon interactions resulting in the formation of a high temperature thermal spike and associated pressure spike. This process promotes atomic mobility that is expected to evolve lattice defects, including the annealing of latent ion tracks. In this work, a multigroup model for electron energy transport is developed and applied to molecular dynamics simulations in the LAMMPS code to examine fission energy deposition and fission effects in nuclear fuel. This technique utilizes MCNP Monte Carlo electron transport calculations to determine the initial injection of fission energy. To provide a more predictive approach than semi-empirical two-temperature models, the electron-phonon interactions are defined to include multiphonon energy transfer as a function of atomic and electron temperature, and are evaluated from electronic structure calculations using the VASP density functional theory code and PHONON lattice dynamics code. Application of this model to fission energy deposition in uranium dioxide predicts ion track formation and fission enhanced atomic mobility behavior within reasonable agreement of experimental trends. Furthermore, simulations of fission fragment interactions with latent ion tracks demonstrate an annealing effect due to this enhanced mobility. DA - 2022/8/1/ PY - 2022/8/1/ DO - 10.1016/j.jnucmat.2022.153797 VL - 566 SP - SN - 1873-4820 KW - Fission KW - Uranium dioxide KW - Nuclear fuel KW - Electron-phonon KW - Molecular dynamics ER - TY - JOUR TI - Nuclear energy myths versus facts support it's expanded use - a review AU - Hayes, Robert Bruce T2 - Cleaner Energy Systems AB - In order to promote a sound basis for considering the role of nuclear in climate change, this review spans the technical topics of social and political debate surrounding nuclear energy with a focus on the objective science of these issues including nuclear waste, accidents and overall risk. Novel aspects include the emergence of nuclear energy as being potentially renewable and the antithesis of Fukushima being an argument for the unacceptable risks associated with the use of nuclear energy. The purpose of this review is to present the facts about nuclear energy divorced from political, social or comparable bias. The results argue nuclear as effectively the most attractive option from almost every possible perspective in which common social discourse would have these painted as unfavourable if not horrific. DA - 2022/7// PY - 2022/7// DO - 10.1016/j.cles.2022.100009 VL - 2 SP - 100009 UR - https://doi.org/10.1016/j.cles.2022.100009 ER - TY - JOUR TI - Ab initio molecular dynamics (AIMD) simulations of NaCl, UCl3 and NaCl-UCl3 molten salts AU - Andersson, D. A. AU - Beeler, B. W. T2 - JOURNAL OF NUCLEAR MATERIALS AB - Ab initio molecular dynamics (AIMD) simulations are used to calculate select thermophysical and thermodynamic properties of NaCl, UCl3 and NaCl-UCl3 molten salts. Following established approaches, the AIMD simulations include a model for Van der Waals interactions. The Langreth & Lundqvist (vDW-DF2), DFT-D3, and density-dependent energy correction (DFT-dDsC) dispersion models are first tested for molten NaCl in order to assess their accuracy for density and heat capacity predictions across a range of temperatures. Based on the NaCl results, the vdW-DF2 and DFT-dDsC methods are extended to the UCl3 system and compared to available experimental data. Next, mixtures of NaCl-UCl3 are investigated and analyzed with respect to the deviation from ideal solution behavior. For the DFT-dDsC simulations, density deviates by up to 2% from an ideal mixture, with the maximum occurring close to the eutectic composition. The mixing energy also deviates from an ideal solution and exhibits a minimum of about -0.074 to eV per formula unit, again close to the eutectic composition. Finally, the compressibility and species diffusivity of the pure and mixed salt systems are calculated. The diffusivities are slightly reduced in the mixed compared to the pure systems and the compressibilities loosely follow a linear correlation as a function of the UCl3 composition. The trends observed for mixing properties are rationalized by correlating them to the coordination chemistry, which emphasizes the importance of maintaining the extended network formed by U and Cl ions as the NaCl concentration increases. The concentration at which breakdown of the extended network occurs, roughly coincides with the minimum of both the mixing energy and the deviation from ideal solution behavior for density. DA - 2022/9// PY - 2022/9// DO - 10.1016/j.jnucmat.2022.153836 VL - 568 SP - SN - 1873-4820 UR - https://doi.org/10.1016/j.jnucmat.2022.153836 ER - TY - JOUR TI - Investigation of ?-(U, Zr) structural properties and its interfacial properties with liquid sodium using ab initio molecular dynamics AU - Aly, Ahmed AU - Beeler, Benjamin AU - Avramova, Maria T2 - JOURNAL OF NUCLEAR MATERIALS AB - In this study, the elastic properties, structural parameters, sound velocity, and Debye temperature of γ−(U,Zr) were computed using ab initio molecular dynamics (AIMD) at temperatures between 1000 K and 1400 K and for Zr content between 0 at.% and 100 at.%. UZr is used as a metallic fuel for Sodium Fast Reactors (SFRs). The study of the mechanical and thermal behavior of these alloys leads to a better data-informed fuel design. The bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio were calculated from the elastic constants and their dependence on Zr content and temperature was investigated, comparing the results with previous computational work and the available experimental data in the literature. Interfacial properties between UZr (up to 32 at.% which typically exists in nuclear fuel) and liquid sodium are also of interest due to the presence of a sodium bond between the fuel and the cladding in metallic nuclear fuel. The interfacial energy between γ−(U,Zr) and liquid sodium, the surface tension of liquid sodium, and the work of adhesion were computed at different temperatures and Zr concentrations. It was demonstrated that γ−(U,Zr) is completely wetted by liquid sodium at all the investigated temperatures and Zr concentrations. This work provides the basis for the determination of interfacial resistances in SFRs and their implementation into heat transfer fuel performance simulations, which will be the subject of future work. DA - 2022/8/15/ PY - 2022/8/15/ DO - 10.1016/j.jnucmat.2022.153835 VL - 567 SP - SN - 1873-4820 UR - https://doi.org/10.1016/j.jnucmat.2022.153835 KW - Uranium KW - Metallic fuel KW - Interfacial energy KW - Elastic constants KW - Sodium bond KW - Sound velocity ER - TY - JOUR TI - Surprisingly high irradiation-induced defect mobility in Fe3O4 as revealed through in situ transmission electron microscopy AU - Owusu-Mensah, Martin AU - Cooper, Jacob AU - Morales, Angelica Lopez AU - Yano, Kayla AU - Taylor, Sandra D. AU - Schreiber, Daniel K. AU - Uberuaga, Blas Pedro AU - Kaoumi, Djamel T2 - MATERIALS CHARACTERIZATION AB - Radiation-induced defects are expected to change the corrosion kinetics when a material is exposed to a corrosive environment. Characterization of the defects forming under irradiation and their ability to move/diffuse is therefore key to understanding how they impact the corrosion kinetics and possibly mechanisms. For that matter, Fe/Fe3O4 interfaces were irradiated using 1 MeV Kr2+ at temperatures of 273 K (25 °C), 573 K (300 °C) and 773 K (500 °C) to a maximum dose of 10 dpa (as measured in the Fe matrix) in situ in a transmission electron microscope. The evolution of the microstructure was followed as a function of the dose and temperature. The formation of defects was followed in the metal and the oxide as well as at the metal/oxide interface and characterized in terms of size and density. The dynamic observation of the spatial distribution of the defects allowed for a qualitative assessment of the mobility of defects in the oxide as a function of temperature, revealing evidence for enhanced mobility even more so than in the Fe matrix. Mechanisms of induced defect mobility in the spinel are discussed to account for the observations. DA - 2022/5// PY - 2022/5// DO - 10.1016/j.matchar.2022.111863 VL - 187 SP - SN - 1873-4189 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85127034818&partnerID=MN8TOARS KW - Fe oxide KW - In-situ transmission electron microscopy KW - Ion irradiation KW - Irradiation-induced defects KW - Defect mobility ER - TY - JOUR TI - Investigation of two concrete thermal energy storage system configurations for continuous power production AU - Mikkelson, Daniel AU - Doster, J. Michael T2 - JOURNAL OF ENERGY STORAGE AB - Two Modelica concrete thermal energy storage (CTES) models are built to analyze potential CTES system designs. The first design is the single-pipe network design wherein a heat transfer fluid (HTF) flows in one direction during heat deposition and the opposite direction during heat removal. All pipes in the network are used for either deposition (charging) or removal (discharging). The second design is a dual-pipe network design in which a network of HTF pipes carries charging fluid and a separate piping network carries discharging HTF. This paper evaluates the operation of these two configurations to produce constant steam. Results indicate that the designs are likely appropriate for different applications: the single-pipe network appears appropriate for batch energy applications, and the dual-pipe network is appropriate for continuous energy applications. DA - 2022/7// PY - 2022/7// DO - 10.1016/j.est.2022.104387 VL - 51 SP - SN - 2352-152X KW - Concrete thermal energy storage KW - Energy storage ER - TY - JOUR TI - Ab initio molecular dynamics investigation of gamma-(U,Zr) structural and thermal properties as a function of temperature and composition AU - Aly, Ahmed AU - Beeler, Benjamin AU - Avramova, Maria T2 - JOURNAL OF NUCLEAR MATERIALS AB - Uranium in its metallic form is considered as a fuel for sodium fast reactors due to its higher thermal conductivity and high fissile material density relative to UO 2 fuel. The metal is alloyed with zirconium to increase its stability at high temperatures and increase its solidus temperature . This work uses ab initio molecular dynamics to perform an evaluation of the mechanical and thermophysical properties of the γ -(U,Zr) system at temperatures between 1000 K and 1400 K. Among these properties are the equilibrium volume, bulk modulus , molar heat capacity , heat of formation , and the surface energy. The obtained results are compared to experimental data and previous computational work available in the literature. This is the first study of γ -(U,Zr) utilizing ab initio molecular dynamics, and reduces thermophysical property knowledge gaps that are currently present in the literature. DA - 2022/4/1/ PY - 2022/4/1/ DO - 10.1016/j.jnucmat.2022.153523 VL - 561 SP - SN - 1873-4820 KW - AIMD KW - DFT KW - Nuclear fuel element KW - Metallic Fuel KW - Uranium KW - U-Zr ER - TY - JOUR TI -

Evaluation of thermophysical properties of the LiCl-KCl system via ab initio and experimental methods

AU - Duemmler, Kai AU - Lin, Yuxiao AU - Woods, Michael AU - Karlsson, Toni AU - Gakhar, Ruchi AU - Beeler, Benjamin T2 - JOURNAL OF NUCLEAR MATERIALS AB - Molten Salt Reactors (MSRs) are envisioned as a potential pathway to safer, more economical nuclear electricity generation and supply of industrial heat. MSRs under consideration today are either solid-fueled salt-cooled designs or liquid-salt-fueled designs with chloride or fluoride based salts. A significant knowledge gap exists in the data for the fundamental properties relevant to fuels and coolants for MSRs that needs to be addressed in order to expedite the technical readiness level of the MSR design concepts. With the rapid development and improvement of computational materials science, computational methods such as Density Functional Theory (DFT) calculations and ab initio Molecular Dynamics (AIMD) simulations are widely used as an effective and reliable tool to investigate the atomic interaction in materials. In this article, the density of the LiCl-KCl system was determined via AIMD calculations and verified using new experimental analyses. AIMD was further utilized to calculate the compressibility, heat capacity, enthalpy of mixing, and Gibbs free energy of mixing. This work spans a wider range of compositions and temperatures than have previously been explored computationally for this pseudo-binary system and provides the basis for further advanced thermophysical property evaluation utilizing AIMD methods. DA - 2022/2// PY - 2022/2// DO - 10.1016/j.jnucmat.2021.153414 VL - 559 SP - SN - 1873-4820 ER - TY - JOUR TI - Digital Engineering for Integrated Modeling and Simulation for Building-Piping Systems Through Interoperability Solutions AU - Crowder, Nicholas AU - Lee, Joomyung AU - Gupta, Abhinav AU - Han, Kevin AU - Bodda, Saran AU - Ritter, Christopher T2 - NUCLEAR SCIENCE AND ENGINEERING AB - Designing piping systems for nuclear power plants involves engineers from multiple disciplines (i.e., thermal hydraulics, mechanical engineering, and structural/seismic) and close coordination with the contractors who build the plant. Any design changes during construction need to be carefully communicated and managed with all stakeholders in order to assess risks associated with the design changes. To allow the quick assessment of building and piping design changes through a streamlined building-piping coupled analysis, this paper presents a novel interoperability solution that converts bidirectionally between building information models (BIMs) and pipe stress models. Any design changes during construction that are shown in an as-built BIM are automatically converted into a pipe stress model. Any further design changes due to building-piping interaction analyses are converted back to the BIM for the contractor and other designers to access the latest model. Two case studies are presented to illustrate the bidirectional conversion that allows an integrated coupled analysis of the building-piping system to account for their interactions. DA - 2022/5/13/ PY - 2022/5/13/ DO - 10.1080/00295639.2022.2055705 SP - SN - 1943-748X KW - Building information model KW - interoperability KW - piping KW - building-piping interaction KW - coupled analysis ER - TY - JOUR TI - Convolution-based frequency domain multiplexing of SiPM readouts using the DRS4 digitizer AU - Mishra, M. AU - Mattingly, J. T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - We present 4:1 multiplexing of organic scintillators, each coupled to a silicon photomultiplier (SiPM), to reduce the need for a large number of digitizer input channels to readout highly pixelated radiation detection systems. Frequency domain multiplexing (FDM) encodes a detector pulse by assigning it a unique frequency via convolution before combining the encoded signal into a single channel. The combined signal is then read through a digitizer input channel. We have designed an FDM system to multiplex four SiPMs using DRS4 digitizer evaluation board from Paul Scherrer Institute (PSI). We demonstrate 4:1 multiplexing of the SiPM fast output signals and pulse recovery from the digitized multiplexed signal using deconvolution. The noise in the recovered pulse introduces a bias and uncertainty in the estimate of energy and timing that changes with pulse height. The relative uncertainty in the estimated energy from the recovered pulse decreases with pulse height with a maximum uncertainty of 3.1% for the low energy pulses (corresponding to 100 keV); the uncertainty in the estimated time pick-off also decreases with pulse height with a maximum uncertainty of 110 ps for the low energy pulses. DA - 2022/2/11/ PY - 2022/2/11/ DO - 10.1016/j.nima.2021.166116 VL - 1025 SP - SN - 1872-9576 KW - Frequency domain multiplexing KW - Convolution KW - deconvolution KW - SiPM fast-output KW - DRS4 digitizer ER - TY - JOUR TI -

The mechanism behind the high radiation tolerance of Fe-Cr alloys

AU - Agarwal, S. AU - Butterling, M. AU - Liedke, M. O. AU - Yano, K. H. AU - Schreiber, D. K. AU - Jones, A. C. L. AU - Uberuaga, B. P. AU - Wang, Y. Q. AU - Chancey, M. AU - Kim, H. AU - Derby, B. K. AU - Li, N. AU - Edwards, D. J. AU - Hosemann, P. AU - Kaoumi, D. AU - Hirschmann, E. AU - Wagner, A. AU - Selim, F. A. T2 - JOURNAL OF APPLIED PHYSICS AB - Fe–Cr alloys are at the forefront for high radiation tolerant materials with long-standing validated performance. Yet, the detailed mechanism behind their high radiation resistance is in question and understanding the effect of varying Cr percentage is a grand challenge limiting further improvements. Here, we applied depth-resolved positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy to study the effect of Cr alloying on the formation and evolution of atomic size clusters induced by ion-irradiation in Fe. We also used atom probe tomography to investigate the possible presence of Cr clusters or α′ phase precipitates with high Cr composition. The study reveals that the well-known resistance to radiation in Fe–Cr alloys may arise from the stabilization of vacancy clusters around Cr atoms, which act as sinks for radiation-induced defects. This implies that Cr atoms do not provide a direct sink for interstitials; rather defect complexes that consist of Cr atoms and vacancies, in turn, act as sinks for irradiation-induced vacancies and interstitials. we also find that lower amounts of Cr create smaller defect clusters that act as efficient sinks for radiation damage, but larger quantities of Cr form a defect structure that is less homogenous and larger in size, resulting in less efficient damage recombination. No evidence of α′ was found before or after irradiation, which indicates that it does not contribute to the observed radiation tolerance. DA - 2022/3/28/ PY - 2022/3/28/ DO - 10.1063/5.0085086 VL - 131 IS - 12 SP - SN - 1089-7550 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85127675955&partnerID=MN8TOARS ER - TY - JOUR TI - Nuclear data uncertainty propagation applied to the versatile test reactor conceptual design AU - Rivas, Andy AU - Martin, Nicolas P. AU - Bays, Samuel E. AU - Palmiotti, Giuseppe AU - Xu, Zhiwen AU - Hou, Jason T2 - NUCLEAR ENGINEERING AND DESIGN AB - The Versatile Test Reactor (VTR) currently under development is a 300 MWth sodium-cooled fast reactor (SFR) fueled with ternary metal alloy fuel, which aims to accelerate the testing of advanced nuclear fuels, materials, instrumentation, and sensors in high flux environments that are necessary to license the next generation of advanced reactor concepts. To support the VTR design process, uncertainties associated with the nuclear data has been propagated through the reactor core neutronics calculation to global parameters of interest, such as the core multiplication factor, kinetic parameters, and various reactivity feedback coefficients, following the sensitivity based uncertainty propagation approach. By folding the sensitivity coefficients, separately computed by the generalized perturbation theory code PERSENT and Monte Carlo code Serpent 2, with the variance–covariance matrices from COMMARA-2.0, we obtain the reaction-wise, isotope-wise, and overall uncertainties for each response of interest due to nuclear data uncertainty. With Serpent 2, the statistical error of the uncertainty is obtained by propagating the statistical error of the sensitivity coefficients through the same process using a newly developed uncertainty propagation method. From both codes, the overall top uncertainty contributors are found to be the cross section of Fe-56 elastic scattering, Na-23 elastic scattering, and U-238 inelastic scattering. The large contributions of the Fe-56 elastic scattering cross sections to global parameters are due to its relatively large relative uncertainty of 5–10% in nuclear data and the large volume of Fe-containing reflector assemblies in the fairly compact VTR core design. Both codes agreed well for the overall uncertainty estimates of all responses of interest, except the delayed neutron fraction, prompt neutron generation time, and the coolant density feedback coefficient, where Serpent 2 yielded a much larger value than PERSENT due to the large statistical error of sensitivity coefficients. The calculated uncertainties are also compared to those associated with other SFR cores. Another outcome of this study is a variance–covariance matrix of reactivity coefficients, which can be used in the subsequent uncertainty propagation to the system level to investigate the impact of identified uncertainties on system responses in the safety analysis. DA - 2022/6// PY - 2022/6// DO - 10.1016/j.nucengdes.2022.111744 VL - 392 SP - SN - 1872-759X UR - http://dx.doi.org/10.1016/j.nucengdes.2022.111744 KW - Uncertainty Propagation KW - Neutronics KW - Versatile Test Reactor KW - Nuclear Data Uncertainty KW - Sodium-Cooled Fast Reactor KW - Sensitivity Analysis ER - TY - JOUR TI - The impact of anisotropic thermal expansion on the isothermal annealing of polycrystalline alpha-uranium AU - Jokisaari, Andrea M. AU - Mahbuba, Khadija AU - Wang, Yuhao AU - Beeler, Benjamin T2 - COMPUTATIONAL MATERIALS SCIENCE AB - Although grain growth impacts microstructural evolution in a wide variety of materials systems, the effect of anisotropic thermal expansion on grain boundary mobility and texture evolution has not been widely studied. Anisotropic thermal expansion occurs in multiple non-cubic metals, and the thermomechanical processing behavior of these materials can be better understood with further study into the impact of thermal expansion on grain boundary mobility and texture evolution. In this work, we develop a mesoscale phase field model of grain growth that includes the effect of anisotropic thermal expansion, which is applied to study polycrystalline α-uranium, a highly anisotropic metal. Three-dimensional simulations on polycrystalline α-uranium with and without thermal expansion eigenstrains are performed to study the grain boundary mobility and texture evolution as a function of temperature. A strain-free temperature of 933 K is selected, and the system is studied within the range of 873–933 K at intervals of ten degrees, resulting in increasing thermal eigenstrain with decreasing temperature. We also estimate a grain boundary mobility prefactor and activation energy based on existing experimental data of isothermal annealing of α-uranium. The grain boundary mobility is found to display significant deviation from Arrhenius behavior with the inclusion of thermal expansion eigenstrain as the amount of thermal eigenstrain (and thus elastic strain energy within the system) increases. This result explains an experimentally observed grain boundary mobility deviation from Arrhenius behavior. Furthermore, the texture evolution is affected, such that the grain orientations become less random with increasing thermal eigenstrain, which could explain experimentally observed texture behavior. These results indicate that the effect of thermal expansion should be considered when predicting the thermomechanical processing behavior of α-uranium and other materials with anisotropic thermal expansion. DA - 2022/4/1/ PY - 2022/4/1/ DO - 10.1016/j.commatsci.2022.111217 VL - 205 SP - SN - 1879-0801 UR - https://doi.org/10.1016/j.commatsci.2022.111217 KW - Grain growth KW - Anisotropic thermal expansion KW - Uranium KW - Texture ER - TY - JOUR TI - A quasi in-situ study on the work hardening and softening mechanisms of Ti-33Zr-12Al-6V alloy AU - Zhang, Fuen AU - Luan, Baifeng AU - Shou, Haoge AU - Zheng, Jiang AU - Zhang, Xinyu AU - Liu, Riping AU - Murty, Korukonda L. T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - In this study, a Ti–33Zr–12Al–6V alloy was prepared, and its work hardening and softening mechanisms were investigated via tensile tests conducted at room temperature. The interaction between the dislocations and strain-induced martensite (SIM) results in work hardening; whereas, the shearing of the grain boundaries by the dislocations for entering the adjacent grains results in work softening, which occurs when the logarithmic strains is between 5.8% and 7.6%. Work softening weakened the effect of work hardening; however, through work softening, the workability, which is insufficient in high-strength β-phase titanium alloys, was significantly increased. The microstructure evolution of Ti–33Zr–12Al–6V alloy under different strains was investigated using the quasi in-situ electron backscatter diffraction and scanning electron microscopy methods during the aforementioned tensile tests. The microstructure near the shear bands was observed via transmission electron microscopy using a focused ion beam. First, the {112}<111> slip systems with a high Schmid factor ( SF ) (>0.25) were activated and, subsequently, the {112}<111> with a low SF (≤0.25) and {011}<111> slip systems were activated in most grains during tensile deformation. • The work hardening and softening behaviors were observed at the β-phase Ti–33Zr–12Al–6V high entropy alloy in ambient temperature tensile. • The quasi in-situ SEM and EBSD methods were applied to study the mechanism of work hardening and softening. • {112}<111 and {011}<111>slip systems were activated at different strain of tensile deformation. DA - 2022/2/17/ PY - 2022/2/17/ DO - 10.1016/j.msea.2022.142694 VL - 835 SP - SN - 1873-4936 KW - Titanium alloy KW - Quasi in-situ KW - Uniaxial tension KW - Strain softening KW - Schmid factor ER - TY - JOUR TI - Demonstration of a Limited Scope Probabilistic Risk Assessment for Autonomous Warehouse Robots With OpenPRA AU - Grimmeisen, Philipp AU - Karimov, Artur AU - Diaconeasa, Mihai A. AU - Morozov, Andrey T2 - Volume 13: Safety Engineering, Risk, and Reliability Analysis; Research Posters AB - Abstract Probabilistic Risk Assessment (PRA) is an indispensable technology to evaluate the risk, dependability, and resilience characteristics of safety-critical systems. Therefore, PRA uses widely adopted methods, such as classical event trees, fault trees, Markov chains, Bayesian networks, and their numerous combinations. To analyze challenging failure scenarios of modern, intelligent, autonomous, and highly dynamic Cyber-Physical Systems (CPS), the integration of multiple PRA methods is needed. This paper presents a PRA approach based on classical Event Tree Analysis (ETA) and Fault Tree Analysis (FTA) and provides the technical description of a new open-source software platform called OpenPRA. Besides, this paper describes a representative case study from the autonomous system domain, focusing on autonomous warehouse robots. DA - 2022/1// PY - 2022/1// DO - 10.1115/imece2021-69998 ER - TY - JOUR TI - Evaluating the Implementation of Distributed Ledger Technology for the Licensing and Regulation of Nuclear Power Plants AU - Pandit, Priyanka AU - Tezbasaran, Alp AU - Earthperson, Arjun AU - Diaconeasa, Mihai A. T2 - Volume 8B: Energy AB - Abstract The approval process from the U.S. Nuclear Regulatory Commission (NRC) for nuclear power plants is sequential. It involves several government bodies such as the Advisory Committee on Reactor Safeguards (ACRS), public meetings, and hearings. If the submissions made to the NRC do not contain enough information to meet the regulation requirements, the NRC issues a Request for Additional Information (RAI). Thus, the licensee has to go through a paperwork-intensive process that involves multiple regulatory agencies for the various licensing requirements. Moreover, sending applications to the NRC is limited to using an electronic submission generation tool called the Packing Slip Wizard (PSW). This paper presents a methodology to implement Distributed Ledger Technology (DLT) to address the need for a real-time, digitized documentation platform in the nuclear power industry’s licensing and regulation process. The evaluation of DLT’s implementation resulted in the formulation of a methodology to accept submissions from an applicant on a web application and storing the received data on a distributed ledger. The presented method offers a real-time submission of the available information of an application. It facilitates the NRC with a real-time feedback capability expediting the review process. RAI’s can be reduced in number by ensuring that the NRC’s information requirements are defined as smart contracts. DA - 2022/1// PY - 2022/1// DO - 10.1115/imece2021-71730 ER - TY - JOUR TI - A Quantitative Approach to Assess the Likelihood of Supply Chain Shortages AU - Pandit, Priyanka AU - Earthperson, Arjun AU - Tezbasaran, Alp AU - Diaconeasa, Mihai A. T2 - Volume 13: Safety Engineering, Risk, and Reliability Analysis; Research Posters AB - Abstract We define supply chains (SCs) as sequences of processes that link the demand and supply of goods or services within a network. SCs are prone to shortages in delivering their output goals due to several factors such as personnel undersupply, inefficient processes, policy failure, equipment malfunction, natural hazards, pandemic outbreaks, power outages, or economic crises. Recent notable supply-chain failures include the 2021 Texas power crisis, personal protection equipment shortages during the COVID-19 pandemic, and regional or global food chain shortages. The consequences of such shortages can range from negligible to devastating. The Texas power crisis resulted in the death of 70 people and left approximately 4.5 billion homes and businesses without power for multiple days. In this paper, we presented a methodology to quantify the failure probability of the throughput of a supply chain. We divided the methodology into two major categories of steps. In the first step, we converted the given or assumed supply chain data into fault trees and quantify them. In the second step, we iterated the quantification of the fault tree to build a supply chain shortage risk profile. We introduced the notion of success criteria for the output from a facility, based on which we included or excluded the facility for quantification. With the inclusion of relevant field data, we believe that our methodology can enable the stakeholders in the supply-chain decision-making process to detect vulnerable facilities and risk-inform prevention and mitigation actions. Applications for this methodology can include construction, inventory stocking, assessing manufacturing quantities, policy changes, personnel allocation, and financial investment for critical industries such as nuclear, pharmaceutical, aviation, etc. DA - 2022/1// PY - 2022/1// DO - 10.1115/imece2021-73696 ER - TY - JOUR TI - Verification Study of the Nuclear PRA for the Mars 2020 Mission Following Accidental Orbital Re-Entry AU - Earthperson, Arjun AU - Diaconeasa, Mihai A. T2 - Volume 13: Safety Engineering, Risk, and Reliability Analysis; Research Posters AB - Abstract Today, Probabilistic Risk Assessment (PRA) plays a vital role in assuring mission success for robotic and crewed missions alike. Current-day PRA techniques integrate multimodal, often black-box analyses to build comprehensive risk profiles. This paper describes a review and verification study of the “Nuclear Risk Assessment for the Mars 2020 Mission Environmental Impact Statement” (N-PRA)[1]. Sandia National Labs conducted the N-PRA for NASA’s Jet Propulsion Laboratory (JPL). More specifically, we have verified the source term calculations associated with the release of radionuclides from a Multi-Mission Radiothermoelectic Generator (MMRTG) power source for a limited set of accident scenarios in the case of an accidental re-entry into Earth Orbit with an Earth impacting trajectory. We achieve this by using analytical methods[2] historically implemented for the Cassini Mission PRA[3] for a failed planetary swingby gravity-assist. Our results are within 28% to 56% of the referenced study. Limitations in our methodology are attributed to a lack of modern simulation-based tools and deterministic methods for modeling complex physical phenomena. The results are interpreted and compared with the values presented by the initial authors, along with comments for improving our current methodology. DA - 2022/1// PY - 2022/1// DO - 10.1115/imece2021-71359 ER - TY - JOUR TI - On the Modeling of Wildfires-Induced Release and Atmospheric Dispersion in Radioactively Contaminated Regions AU - Polat, Damla AU - Diaconeasa, Mihai A. T2 - Volume 13: Safety Engineering, Risk, and Reliability Analysis; Research Posters AB - Abstract Nuclear energy is one of the most efficient types of electricity production. However, it is one of the biggest fears of people due to the potential radiation effects on human health. Despite the major developments in the nuclear sector, some gaps need to be studied for the higher safety scrutiny of nuclear power plants (NPPs). Besides technical advances for the safer management of an NPP, another important part is having a well-constructed and planned probabilistic risk assessment and management. Realistic probabilistic risk assessment and management provide proper emergency response in case of an accident or hazardous situation to human health. On the other hand, aside from the radiation emitted directly from radioactive sources inside the NPP, there may be indirect radiation emission from dispersions outside the plant’s protected area. For example, we can look at forest fires occurring in radioactively contaminated areas surrounding NPPs that suffered accidents with releases, such as Chernobyl or Fukushima Daiichi. Radioactive particles produced by burning contaminated forests could spread in the air and threaten public health. It has already been observed that fires in forests around Chernobyl can increase the level of radiation in the air. Such events have the possibility to occur in all areas where nuclear facilities are located. The forests contaminated after the Fukushima Daiichi NPP accident, resemble the ones at Chernobyl. This study aims to develop the knowledge for an early sensing and emergency response by doing an atmospheric dispersion modeling and supporting a probabilistic risk assessment for a wildfire scenario in radioactively contaminated areas, such as Chernobyl and Fukushima Daiichi. Also, this study provides a pathway to assessing the risk of nuclear contamination caused by wildfires around nuclear facilities. DA - 2022/1// PY - 2022/1// DO - 10.1115/imece2021-71460 ER - TY - JOUR TI - On the Use of Probabilistic Risk Assessment for the Protection of Small Modular Reactors Against Terrorist Attacks AU - Polat, Burak AU - Diaconeasa, Mihai A. T2 - Volume 13: Safety Engineering, Risk, and Reliability Analysis; Research Posters AB - Abstract Safety and security are two of the most important requirements of the nuclear industry. In the event of a potential problem, the consequences can have serious implications for the public and the environment. Measures should be taken against various hazards and threats by analyzing possible realistic scenarios. Therefore, probabilistic risk assessment is one of the necessary technologies to achieving safe and secure nuclear facilities. In the study, a limited scope probabilistic risk assessment was made for a possible terrorist attack against a generic small modular reactor (SMR). A possible attack threat was selected to develop scenarios by following a probabilistic risk assessment approach. In the scenarios created, terrorists have to pass all physical barriers that security guards protect. Thus, the decisions and actions of the security guards directly affect the result of the attack. To analyze these events, a human reliability assessment (HRA) was employed. In the first study, each security guard’s decision-making process was analyzed using the Standardized Plant Analysis Risk Human Reliability Assessment (SPAR-H) method. The purpose of its use in this study is to verify the SPAR-H method’s applicability for security applications. In this paper, we give the likelihoods of each security guard making a decision and taking action to prevent terrorists from passing obtained using the SPAR-H method. Besides, event tree and fault tree analyses were performed using the SAPHIRE PRA software. Finally, since the current HRA methods were designed for control room operators, we introduce a new model-based HRA methodology applicable for security guards to be used in physical security PRAs. DA - 2022/1// PY - 2022/1// DO - 10.1115/imece2021-71504 ER - TY - JOUR TI - A framework to implement human reliability analysis during early design stages of advanced reactors AU - Hamza, Mostafa AU - Diaconeasa, Mihai A. T2 - PROGRESS IN NUCLEAR ENERGY AB - Nuclear power plants require human actions throughout their lifecycle from design, construction, operation, and decommissioning. However, for advanced reactors (e.g., Generation IV), the reliance on human intervention in safety-related actions is expected to be reduced or completely replaced by automated actions. The Probabilistic Risk Assessment (PRA) Standard for Advanced Non-LWR Nuclear Power Plants requires that the impacts of all operator actions are captured and incorporated in the risk of the modeled plant. Moreover, the Modernization of Technical Requirements for Licensing Advanced Reactors requires human reliability analysis (HRA) to be included throughout all design and PRA development stages. However, due to the lack of details during the early design stages, HRA is often postponed until the design is mature enough. Conducting HRA in later design stages, though it may be adequate in capturing pre-, at-, and post-initiators comes short of informing the design itself in the iterative design lifecycle. Hence, this paper presents a framework to include HRA during the design's early stages, pre-conceptual or conceptual. The proposed framework provides a process for the removal of operator actions that do not contribute to the risk and the identification of all key operator actions that are critical to the safety of the design. The results of this framework are then used to inform the design of those safety-related operator actions to update the design further. Then, using information from the updated design, this framework can be reapplied to investigate the impact of the design update on human reliability. The PRA model of the X-energy's pre-conceptual Xe-100 high-temperature gas-cooled pebble-bed reactor (HTGR-PB) design is used to demonstrate the approach. In the pre-conceptual Xe-100 PRA model, also called Phase 0 PRA model, human actions were considered an integral part of analyzing the plant response to different initiating events. Hence, in this paper, all possible human actions in the Xe-100 PRA model are identified, analyzed, and removed to emulate a design relying only on the available automated control systems. The preliminary results of this assessment show how safe the Xe-100 design is even without crediting any human actions. The results also list necessary sequences in which operator actions are critical to the risk profile of the design. DA - 2022/4// PY - 2022/4// DO - 10.1016/j.pnucene.2022.104171 VL - 146 SP - SN - 1878-4224 UR - https://doi.org/10.1016/j.pnucene.2022.104171 KW - PRA KW - HRA KW - HTGR-PB KW - Advanced reactors ER - TY - JOUR TI - Predictions of component Remaining Useful Lifetime Using Bayesian Neural Network AU - Rivas, Andy AU - Delipei, Gregory Kyriakos AU - Hou, Jason T2 - PROGRESS IN NUCLEAR ENERGY AB - The Machine Prognostics and Health Management (PHM) are concerned with the prediction of the Remaining Useful Lifetime (RUL) of assets. Accurate real-time RUL predictions are necessary when developing an efficient predictive maintenance (PdM) framework for equipment health assessment. If correctly implemented, a PdM framework can maximize the interval between maintenance operations, minimize the cost and number of unscheduled maintenance operations, and improve overall availability of the large facilities like nuclear power plants (NPPs). This is especially important for nuclear power facilities to maximize capacity factor and reliability. In this work, we propose a data-driven approach to make predictions of both the RUL and its uncertainty using a Bayesian Neural Network (BNN). The BNN utilizes the Bayes by backprop algorithm with variational inference to estimate the posterior distribution for each trainable parameter so that the model output is also a PDF from which one can draw the mean prediction and the associated uncertainty. To learn the correlations between various time-series sensor data measurements, a time window approach is implemented with a two-stage noise filtering process for incoming sensor measurements to enhance the feature extraction and overall model performance. As a proof of concept, the NASA Commercial Modular Aero Propulsion System Simulation (C-MAPPS) datasets are utilized to assess the performance of the BNN model. The modeled system can be treated as a surrogate for turbine generators used in NPPs due to the similar mode of operation, degradation, and measurable variables. Comparisons against other state-of-the-art algorithms on the same datasets indicate that the BNN model can not only make predictions with comparable level of accuracy, but also offer the benefit of estimating uncertainty associated with the prediction. This additional uncertainty, which can be continuously updated as more measurement data are collected, can facilitate the decision-making process with a quantifiable confidence level within a PdM framework. Additional advantages of the BNN are showcased, such as providing component maintenance ranges and model executing frequency, with an example of how the BNN estimated uncertainty can be used to support the continuous predictive maintenance. A PdM framework based on a BNN will allow for utilities to make more informed decisions on the optimal time for maintenance so that the loss of revenue can be minimized from planned and unplanned maintenance outages. DA - 2022/4// PY - 2022/4// DO - 10.1016/j.pnucene.2022.104143 VL - 146 SP - SN - 1878-4224 UR - http://dx.doi.org/10.1016/j.pnucene.2022.104143 KW - Prognostics and Health Management KW - Remaining Useful Life KW - Bayesian Neural Network KW - Deep learning KW - Predictive maintenance KW - C-MAPSS dataset ER - TY - JOUR TI - Plasma-driven biocatalysis: In situ hydrogen peroxide production with an atmospheric pressure plasma jet increases the performance of OleT(JE) when compared to adding the same molar amount of hydrogen peroxide in bolus AU - Wapshott-Stehli, Hannah L. AU - Myers, Brayden G. AU - Quesada, Maria J. Herrera AU - Grunden, Amy AU - Stapelmann, Katharina T2 - PLASMA PROCESSES AND POLYMERS AB - Abstract Enzymes like fatty acid peroxygenase OleT JE are desirable enzymes for the industry. While they require inexpensive hydrogen peroxide for activity, the same hydrogen peroxide also causes overoxidation of their reactive heme center. Here, we generate hydrogen peroxide slowly in situ using the Cooperation in Science and Technology (COST)‐Jet, an atmospheric pressure plasma jet, to avoid overoxidizing OleT JE . The COST‐Jet was operated in helium with a water admixture to provide hydrogen peroxide for OleT JE activity. This helium/water admixture produced the highest enzyme turnover numbers after 2 min of treatment. These turnover numbers were even superior to using an equimolar amount of hydrogen peroxide to treat the enzymes exogenously, showing that this plasma source can provide a reliable amount of reaction mediator to support OleT JE activity. DA - 2022/2/3/ PY - 2022/2/3/ DO - 10.1002/ppap.202100160 VL - 2 SP - SN - 1612-8869 UR - https://doi.org/10.1002/ppap.202100160 KW - atmospheric pressure plasma jet KW - biocatalysis KW - cytochrome P450 enzymes KW - hydrogen peroxide KW - plasma liquid chemistry ER - TY - JOUR TI - Low-Temperature Plasma for Biology, Hygiene, and Medicine: Perspective and Roadmap AU - Laroussi, Mounir AU - Bekeschus, Sander AU - Keidar, Michael AU - Bogaerts, Annemie AU - Fridman, Alexander AU - Lu, Xinpei AU - Ostrikov, Kostya AU - Hori, Masaru AU - Stapelmann, Katharina AU - Miller, Vandana AU - Reuter, Stephan AU - Laux, Christophe AU - Mesbah, Ali AU - Walsh, James AU - Jiang, Chunqi AU - Thagard, Selma Mededovic AU - Tanaka, Hiromasa AU - Liu, Dawei AU - Yan, Dayun AU - Yusupov, Maksudbek T2 - IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES AB - Plasma, the fourth and most pervasive state of matter in the visible universe, is a fascinating medium that is connected to the beginning of our universe itself. Man-made plasmas are at the core of many technological advances that include the fabrication of semiconductor devices, which enabled the modern computer and communication revolutions. The introduction of low temperature, atmospheric pressure plasmas to the biomedical field has ushered a new revolution in the healthcare arena that promises to introduce plasma-based therapies to combat some thorny and long-standing medical challenges. This article presents an overview of where research is at today and discusses innovative concepts and approaches to overcome present challenges and take the field to the next level. It is written by a team of experts who took an in-depth look at the various applications of plasma in hygiene, decontamination, and medicine, made critical analysis, and proposed ideas and concepts that should help the research community focus their efforts on clear and practical steps necessary to keep the field advancing for decades to come. DA - 2022/2// PY - 2022/2// DO - 10.1109/TRPMS.2021.3135118 VL - 6 IS - 2 SP - 127-157 SN - 2469-7303 UR - https://doi.org/10.1109/TRPMS.2021.3135118 KW - Bacteria KW - cancer KW - cold plasma KW - decontamination KW - plasma medicine KW - radicals KW - reactive species KW - wound healing ER - TY - JOUR TI - The Effect of Fluorinated Solvents on the Physicochemical Properties, Ionic Association, and Free Volume of a Prototypical Solvate Ionic Liquid AU - Burba, Christopher M. AU - Feightner, Kylie AU - Liu, Ming AU - Hawari, Ayman T2 - CHEMPHYSCHEM AB - Solvate ionic liquid (SIL) synthesis and properties depend on a delicate balancing of cation-solvent and cation-anion interactions to produce materials containing only cation-solvent complexes and solvent-separated anions. Most SILs meeting these characteristics fall within the paradigm of oligomeric ethylene oxides (e.g. glymes and glycols) and lithium salts. Targeted functionalization of solvent molecules to achieve desired properties is a relatively unexplored avenue of research. Fluorinated solvents have significantly different electric charge distributions compared to their nonfluorinated analogs. We test the impact of solvent fluorination for a SIL created from equimolar mixtures of lithium bis(trifluoromethylsulfonyl)imide (LiNTf2 ) and triethylene glycol (TEG), hereafter [(TEG)1 Li]NTf2 . In the first experiment, TEG is partially substituted with 2,2,4,4,5,5,7,7-octafluoro-3,6-dioxaoctane-1,8-diol (FTEG). This leads to a precipitous decrease in ionic conductivity and larger quantities of ionically-associated Li(NTf2 )2- species, as detected with vibrational spectroscopy. These observations suggest FTEG does not readily coordinate Li+ ions in a manner analogous to TEG. Computational studies reinforce this conclusion. Relative complex cation stabilities are ranked as [(FTEG)1 Li]+ >[(TEG)1 Li]+ . A second experiment adds FTEG as a diluent to [(TEG)1 Li]NTf2 . This places FTEG and TEG in competition to coordinate a limited number of Li+ ions. The resulting mixtures exhibit conductivity enhancement over the parent SIL and minimal changes in ion speciation due to the poor Li+ binding by FTEG compared to TEG. Positron annihilation lifetime spectroscopic studies point to increased amounts of free volume upon dilution of FTEG. This likely explains the origin of the conductivity and viscosity enhancements. DA - 2022/1/21/ PY - 2022/1/21/ DO - 10.1002/cphc.202100548 SP - SN - 1439-7641 KW - density functional calculations KW - ionic conductivity KW - perfluorinated solvents KW - solvate ionic liquids KW - vibrational spectroscopy ER - TY - PCOMM TI - Achieving high hetero-deformation induced (HDI) strengthening and hardening in brass by dual heterostructures AU - Fang, X. T. AU - Li, Z. K. AU - Wang, Y. F. AU - Ruiz, M. AU - Ma, X. L. AU - Wang, H. Y. AU - Zhu, Y. AU - Schoell, R. AU - Zheng, C. AU - Kaoumi, D. AU - Zhu, Y. T. AB - Heterostructured materials have a superior combination of strength and ductility, due to their ability to produce hetero-deform induced (HDI) strengthening and hardening. Therefore, achieving high HDI strengthening and hardening is the primary goal for designing heterostructures. Here we report a dual heterostructure in brass that consists of the heterogeneous lamella and gradient structure, fabricated by rolling, partial annealing, and rotationally accelerated shot peening (RASP). The dual heterostructures are able to generate extra interfaces of heterogeneity compared to the single heterostructures, which could lead to higher HDI strengthening and hardening, and a more superior combination of strength and ductility. This finding presents a new pathway to designing heterostructures in metallic materials. DA - 2022/1/30/ PY - 2022/1/30/ DO - 10.1016/j.jmst.2021.03.088 SP - 244-247 UR - https://doi.org/10.1016/j.jmst.2021.03.088 ER - TY - JOUR TI - Direct Numerical Simulation of Bubble Formation Through a Submerged "Flute" With Experimental Validation AU - Pillai, Naveen AU - Sponsel, Nicholas L. AU - Stapelmann, Katharina AU - Bolotnov, Igor A. T2 - JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME AB - Abstract Direct numerical simulation (DNS) is often used to uncover and highlight physical phenomena that are not properly resolved using other computational fluid dynamics methods due to shortcuts taken in the latter to cheapen computational cost. In this work, we use DNS along with interface tracking to take an in-depth look at bubble formation, departure, and ascent through water. To form the bubbles, air is injected through a novel orifice geometry not unlike that of a flute submerged underwater, which introduces phenomena that are not typically brought to light in conventional orifice studies. For example, our single-phase simulations show a significant leaning effect, wherein pressure accumulating at the trailing nozzle edges leads to asymmetric discharge through the nozzle hole and an upward bias in the flow in the rest of the pipe. In our two-phase simulations, this effect is masked by the surface tension of the bubble sitting on the nozzle, but it can still be seen following departure events. After bubble departure, we observe the bubbles converge toward an ellipsoidal shape, which has been validated by experiments. As the bubbles rise, we note that local variations in the vertical velocity cause the bubble edges to flap slightly, oscillating between relatively low and high velocities at the edges. DA - 2022/2/1/ PY - 2022/2/1/ DO - 10.1115/1.4052051 VL - 144 IS - 2 SP - SN - 1528-901X ER - TY - JOUR TI - Bayesian inverse uncertainty quantification of a MOOSE-based melt pool model for additive manufacturing using experimental data AU - Xie, Ziyu AU - Jiang, Wen AU - Wang, Congjian AU - Wu, Xu T2 - ANNALS OF NUCLEAR ENERGY AB - Additive manufacturing (AM) technology is being increasingly adopted in a wide variety of application areas due to its ability to rapidly produce, prototype, and customize designs. AM techniques afford significant opportunities in regard to nuclear materials, including an accelerated fabrication process and reduced cost. High-fidelity modeling and simulation (M\&S) of AM processes is being developed in Idaho National Laboratory (INL)'s Multiphysics Object-Oriented Simulation Environment (MOOSE) to support AM process optimization and provide a fundamental understanding of the various physical interactions involved. In this paper, we employ Bayesian inverse uncertainty quantification (UQ) to quantify the input uncertainties in a MOOSE-based melt pool model for AM. Inverse UQ is the process of inversely quantifying the input uncertainties while keeping model predictions consistent with the measurement data. The inverse UQ process takes into account uncertainties from the model, code, and data while simultaneously characterizing the uncertain distributions in the input parameters--rather than merely providing best-fit point estimates. We employ measurement data on melt pool geometry (lengths and depths) to quantify the uncertainties in several melt pool model parameters. Simulation results using the posterior uncertainties have shown improved agreement with experimental data, as compared to those using the prior nominal values. The resulting parameter uncertainties can be used to replace expert opinions in future uncertainty, sensitivity, and validation studies. DA - 2022/1// PY - 2022/1// DO - 10.1016/j.anucene.2021.108782 VL - 165 SP - SN - 1873-2100 KW - Inverse uncertainty quantification KW - Melt pool KW - Additive manufacturing ER - TY - JOUR TI - The ubiquity of nuclear fission reactors throughout time and space AU - Hayes, Robert B. T2 - PHYSICS AND CHEMISTRY OF THE EARTH AB - The evidence for a natural uranium fission reactor in Oklo, Gabon (Africa) begs the question as to whether this was the only one to have ever occurred on earth or elsewhere. Modern nuclear terminology classifies uranium as highly enriched uranium when the U235 content exceeds 20% which is shown comparable to projecting back ca 4.5e9 yr for terrestrial uranium isotopic abundances. At that time, the natural uranium content of the earth would have been classified as highly enriched uranium. With one verified natural criticality event, more events are postulated both on earth and throughout our galaxy. The latter effect should result in some background contribution to gamma ray burst events placing nuclear reactors as an expected ubiquitous natural phenomenon throughout time and space. DA - 2022/2// PY - 2022/2// DO - 10.1016/j.pce.2021.103083 VL - 125 SP - SN - 1873-5193 UR - https://doi.org/10.1016/j.pce.2021.103083 ER - TY - JOUR TI - Propagation of VHTRC manufacturing uncertainties with RAVEN/PHISICS AU - Rouxelin, Pascal AU - Alfonsi, Andrea AU - Strydom, Gerhard AU - Avramova, Maria AU - Ivanov, Kostadin T2 - ANNALS OF NUCLEAR ENERGY AB - The International Atomic Energy Agency recently concluded a Coordinated Research Program (CRP) to evaluate the effect of propagation of uncertainties on design and safety parameters in High Temperature Gas-cooled Reactors (HTGRs). This CRP catalyzed the development of novel software and methods relevant to HTGR uncertainty analysis. In the framework of this CRP, the statistical analysis code RAVEN was coupled to the neutron transport code PHISICS, using 6-group cross section libraries generated with the modules TRITON/NEWT from SCALE 6.2.1. This article describes the mechanics of the RAVEN/PHISICS sequence, and reports the effects of manufacturing uncertainties on integral parameter uncertainties found in the Very High Temperature Reactor Critical (VHTRC) core. The VHTRC experimental results included propagation of manufacturing uncertainties to obtain eigenvalue (keff) and temperature coefficient (αT) uncertainties. RAVEN/PHISICS was used to reproduce this analysis and to compare the predicted output uncertainties to the experimental measurements on the three VHTRC cores (HC-I, HP, HC-II). Results from the sequence agree with the experimental values (σ[keff] ~ 0.00300). The analysis also focuses on the interpretation of input uncertainties. The simulations conducted with RAVEN/PHISICS demonstrated the input uncertainties can induce a threefold increase in the resulting output uncertainties, depending on the mathematical modeling of the raw input uncertainties. In particular, the use of a unique uncertainty value repeated over lattice elements constitutes the major contribution to the keff and αT uncertainties, while modeling these uncertainties with random independent values leads to negligible keff and αT uncertainties, due to cancellation of errors. The propagation of the manufacturing uncertainties was also repeated using 56 energy groups in the neutron transport calculations, and showed a moderate impact on the output (keff, αT) uncertainties (~10 % difference) compared to the base-case 6-group simulations. DA - 2022/1// PY - 2022/1// DO - 10.1016/j.anucene.2021.108667 VL - 165 SP - SN - 1873-2100 KW - PHISICS KW - RAVEN KW - VHTRC KW - Manufacturing Uncertainties KW - Monte Carlo Sampling ER - TY - JOUR TI - Digital-twin-based improvements to diagnosis, prognosis, strategy assessment, and discrepancy checking in a nearly autonomous management and control system AU - Lin, Linyu AU - Athe, Paridhi AU - Rouxelin, Pascal AU - Avramova, Maria AU - Gupta, Abhinav AU - Youngblood, Robert AU - Lane, Jeffrey AU - Dinh, Nam T2 - ANNALS OF NUCLEAR ENERGY AB - The Nearly Autonomous Management and Control System (NAMAC) is a comprehensive control system that assists plant operations by furnishing control recommendations to operators in a broad class of situations. This study refines a NAMAC system for making reasonable recommendations during complex loss-of-flow scenarios with a validated Experimental Breeder Reactor II simulator, digital twins improved by machine-learning algorithms, a multi-attribute decision-making scheme, and a discrepancy checker for identifying unexpected recommendation effects. We assess the performance of each NAMAC component, while we demonstrate and evaluated the capability of NAMAC in a class of loss-of-flow scenarios. DA - 2022/2// PY - 2022/2// DO - 10.1016/j.anucene.2021.108715 VL - 166 SP - SN - 1873-2100 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85115958204&partnerID=MN8TOARS KW - autonomous control KW - digital twin KW - diagnosis KW - prognosis ER - TY - JOUR TI - Thermoluminescence and optically stimulated luminescence response of Al2O3 coatings deposited by mist-chemical vapor deposition AU - Kanies, Bryant AU - Hayes, Robert AU - Yang, Ge T2 - Radiation Physics and Chemistry AB - Aluminum oxide (Al2O3) is a widely used ceramic material which can be applied as a protective coating on metallic structures to improve corrosion resistance and mechanical properties. Al2O3 also has great potential as a functional thin film device in optoelectronics. When it is doped with carbon (Al2O3:C), this material system can serve as a reliable radiation dosimeter. The combination of optoelectronic, dosimetric, and protective properties demonstrated by Al2O3 uniquely positions it for dual use applications in nuclear forensics, nonproliferation and safeguards, emergency response, retrospective dosimetry, and nondestructive inspection. In this study, an innovative ultrasonic mist-chemical vapor deposition (Mist-CVD) system was used to deposit thin (nm level) Al2O3 coatings on 304 stainless steel substrates. The single aliquot regeneration (SAR) and additive dose reconstruction techniques were then used to investigate the thermoluminescence (TL) and optically stimulated luminescence (OSL) response of the coated substrates to increasing doses of β irradiation. This study demonstrates that nm-thick Al2O3 coatings hold promise as novel nano-dosimeters which could be leveraged for a series of applications such as nonproliferation and safeguards, retrospective dosimetry, and nondestructive inspection. DA - 2022/2// PY - 2022/2// DO - 10.1016/j.radphyschem.2021.109860 VL - 191 SP - 109860 J2 - Radiation Physics and Chemistry LA - en OP - SN - 0969-806X UR - http://dx.doi.org/10.1016/j.radphyschem.2021.109860 DB - Crossref KW - Thermoluminescence KW - Optically stimulated luminescence KW - Mist-chemical vapor deposition KW - Retrospective dosimetry KW - Aluminum oxide ER -