TY - RPRT TI - Attenuation of Gamma Rays in New Concrete Forms” AU - Bourham, Mohamed AU - Rizkalla, Sami AU - Khalil, Mervat AU - Winfrey, Leigh AU - Nowak, Joshua A3 - Grancrete, Inc. DA - 2010/1// PY - 2010/1// M3 - Technical Report PB - Grancrete, Inc. ER - TY - JOUR TI - Surface strengthening of Ti3SiC2 through magnetron sputtering of Mo and Zr and subsequent annealing AU - Guo, H. AU - Li, A. AU - Zhang, J. AU - He, L. AU - Zhou, Y. T2 - Journal of the European Ceramic Society AB - Magnetron sputtering deposition of Mo and Zr and subsequent annealing were conducted with the motivation to modify the surface hardness of Ti3SiC2. For Mo-coated Ti3SiC2, Si diffused outward into the Mo layer and reacted with Mo to form molybdenum silicides in the temperature range of 1000–1100 °C. The MoSi2 layer, however, cracked and easily spalled off. For Zr-coated Ti3SiC2, Si also diffused outward to form Zr–Si intermetallic compounds at 900–1100 °C. The Zr–Si compounds layer had good adhesion with Ti3SiC2 substrate, which resulted in the increased surface hardness. DA - 2010/// PY - 2010/// DO - 10.1016/j.jeurceramsoc.2009.04.042 VL - 30 IS - 10 SP - 2123-2130 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77952950712&partnerID=MN8TOARS KW - Ti3SiC2 KW - Surface strengthening KW - Magnetron sputtering KW - Microhardness ER - TY - JOUR TI - Reciprocating friction and wear behavior of Zr2[Al(Si)] 4C5 and Zr2[Al(Si)]4C 5-SiC composite against Si3N4 ball AU - Wu, L. AU - He, L.-F. AU - Chen, J.-X. AU - Lu, X.-P. AU - Zhou, Y.-C. T2 - Journal of the American Ceramic Society AB - The reciprocating sliding friction and wear properties of two novel materials of Zr 2 [Al(Si)] 4 C 5 ceramic and Zr 2 [Al(Si)] 4 C 5 –30 vol% SiC composite against Si 3 N 4 ball were investigated. The sliding friction process of Zr 2 [Al(Si)] 4 C 5 against Si 3 N 4 experiences two different stages under constant normal load and involves friction and wear mechanism transition. The static coefficient of friction increases with an increasing normal load. The friction force mainly comes from the interfacial shear between Si 3 N 4 ball and Zr 2 [Al(Si)] 4 C 5 , which changes with varied sliding distances and normal loads. In contrast, the friction process of the composite experiences one stage and the friction coefficient is not related to the test durations and normal loads. The friction force between Zr 2 [Al(Si)] 4 C 5 –30 vol% SiC composite and Si 3 N 4 is mainly from the plough between SiC particles and Si 3 N 4 ball, which appears not to be influenced significantly by different normal load and sliding distance. In addition, microfracture induced mechanical wear is the rate‐control wear mechanism in both Zr 2 [Al(Si)] 4 C 5 and Zr 2 [Al(Si)] 4 C 5 –30 vol% SiC composite. Adding SiC improves the wear resistance of the single‐phase material, because the second phase bears normal load and slows down material removal. DA - 2010/// PY - 2010/// DO - 10.1111/j.1551-2916.2010.03718.x VL - 93 IS - 8 SP - 2369-2376 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77955757370&partnerID=MN8TOARS ER - TY - JOUR TI - Oxidation behavior of ternary carbide ceramics in Hf-Al-C system in air AU - He, L.-F. AU - Li, J.-J. AU - Nian, H.-Q. AU - Wang, X.-H. AU - Bao, Y.-W. AU - Li, M.-S. AU - Wang, J.-Y. AU - Zhou, Y.-C. T2 - Journal of the American Ceramic Society AB - The oxidation behavior of Hf–Al–C ceramics containing 37.5 wt% Hf 3 Al 3 C 5 , 30.5 wt% Hf 2 Al 4 C 5 , and 32.0 wt% Hf 3 Al 4 C 6 has been investigated at 900°–1300°C in air. The oxidation kinetics approximately follows a linear law with the activation energy of 194±12 kJ/mol. The oxidation resistance of Hf–Al–C ceramics at high temperature is superior to HfC. The oxide scale is porous and composed of well‐mixed t ‐HfO 2 and Al 2 O 3 as well as residual free carbon. The stabilization mechanisms of t ‐HfO 2 and free carbon have been discussed. The simultaneous oxidation of Hf and Al in Hf–Al–C ceramics can be attributed to their close oxygen affinity as well as the strong coupling between Hf–C blocks and Al–C units in the crystal structures. DA - 2010/// PY - 2010/// DO - 10.1111/j.1551-2916.2010.03891.x VL - 93 IS - 10 SP - 3427-3431 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-78649552470&partnerID=MN8TOARS ER - TY - JOUR TI - Microstructure, mechanical, thermal, and oxidation properties of a Zr2[Al(Si)]4C5-SiC composite prepared by in situ reaction/hot-pressing AU - He, L.-F. AU - Li, F.-Z. AU - Lu, X.-P. AU - Bao, Y.-W. AU - Zhou, Y.-C. T2 - Journal of the European Ceramic Society AB - The microstructure, mechanical and thermal properties, as well as oxidation behavior, of in situ hot-pressed Zr2[Al(Si)]4C5–30 vol.% SiC composite have been characterized. The microstructure is composed of elongated Zr2[Al(Si)]4C5 grains and embedded SiC particles. The composite shows superior hardness (Vickers hardness of 16.4 GPa), stiffness (Young's modulus of 386 GPa), strength (bending strength of 353 MPa), and toughness (fracture toughness of 6.62 MPa m1/2) compared to a monolithic Zr2[Al(Si)]4C5 ceramic. Stiffness is maintained up to 1600 °C (323 GPa) due to clean grain boundaries with no glassy phase. The composite also exhibits higher specific heat capacity and thermal conductivity as well as better oxidation resistance compared to Zr2[Al(Si)]4C5. DA - 2010/// PY - 2010/// DO - 10.1016/j.jeurceramsoc.2010.02.005 VL - 30 IS - 11 SP - 2147-2154 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77953541682&partnerID=MN8TOARS KW - Carbides KW - Microstructure KW - Mechanical properties KW - Thermal properties KW - Corrosion ER - TY - JOUR TI - Mechanisms and kinetics of the hydrothermal oxidation of bulk titanium silicon carbide AU - Zhang, H. AU - Presser, V. AU - Berthold, C. AU - Nickel, K.G. AU - Wang, X. AU - Raisch, C. AU - Chassé, T. AU - He, L. AU - Zhou, Y. T2 - Journal of the American Ceramic Society AB - Hydrothermal oxidation of bulk Ti 3 SiC 2 in continuous water flow was studied at 500°–700°C under a hydrostatic pressure of 35 MPa. The oxidation was weak at 500°–600°C and accelerated at 700°C due to the formation of cracks in oxides. The kinetics obeyed a linear time‐law. Due to the high solubility of silica in hydrothermal water, the resulting oxide layers only consisted of titanium oxides and carbon. Besides general oxidation, two special modes are very likely present in current experiments: (1) preferential hydrothermal oxidation of lattice planes perpendicular to the c ‐axis inducing cleavage of grains and (2) uneven hydrothermal oxidation related to the occurrence of TiC and SiC impurity inclusions. Nonetheless the resistance against hydrothermal oxidation is remarkably high up to 700°C. DA - 2010/// PY - 2010/// DO - 10.1111/j.1551-2916.2009.03570.x VL - 93 IS - 4 SP - 1148-1155 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77950478718&partnerID=MN8TOARS ER - TY - JOUR TI - Mechanical and thermal properties of a Hf2[Al(Si)]4C5 ceramic prepared by in situ reaction/hot-pressing AU - He, L.F. AU - Nian, H.Q. AU - Lu, X.P. AU - Bao, Y.W. AU - Zhou, Y.C. T2 - Scripta Materialia AB - Predominantly single-phase Hf2[Al(Si)]4C5 ceramic has been fabricated by an in situ reaction/hot-pressing method using Hf, Al, Si and graphite as starting materials. Hf2[Al(Si)]4C5 shows comparable mechanical properties to Zr2[Al(Si)]4C5, and lower hardness and stiffness but higher strength and toughness than HfC. The stiffness decreases slowly with temperature and at 1600 °C it remains 83% of that at ambient temperature. Compared to Zr2[Al(Si)]4C5 and HfC, however, Hf2[Al(Si)]4C5 exhibits a relatively higher coefficient of thermal expansion, an intermediate specific heat capacity and a lower thermal conductivity. DA - 2010/// PY - 2010/// DO - 10.1016/j.scriptamat.2009.12.020 VL - 62 IS - 6 SP - 427-430 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-73549118598&partnerID=MN8TOARS KW - Carbides KW - Hot-pressing KW - High temperature KW - Mechanical property KW - Thermal property ER - TY - JOUR TI - Crystal structure and theoretical elastic property of a new ternary ceramic HfAl4C4 AU - Nian, H. AU - He, L. AU - Li, F. AU - Wang, J. AU - Zhou, Y. T2 - Journal of the American Ceramic Society AB - HfAl 4 C 4 , a new ternary aluminum carbide, was discovered and its crystal structure was determined by a combination of X‐ray diffraction, transmission electron microscopy, and first‐principles calculations. The crystal structure is trigonal belonging to the space group. The refined lattice constants are a =0.3308 nm, c =2.190 nm. First‐principles method was used to calculate the theoretical second‐order elastic constants, bulk modulus, shear modulus, and the Young's modulus of HfAl 4 C 4 . It shows that HfAl 4 C 4 has relatively high elastic stiffness. DA - 2010/// PY - 2010/// DO - 10.1111/j.1551-2916.2009.03543.x VL - 93 IS - 4 SP - 1164-1168 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77950477327&partnerID=MN8TOARS ER - TY - JOUR TI - In situ reaction synthesis and mechanical properties of TaC-TaSi 2 composites AU - Hu, C. AU - He, L. AU - Li, F. AU - Wu, L. AU - Wang, J. AU - Li, M. AU - Bao, Y. AU - Zhou, Y. T2 - International Journal of Applied Ceramic Technology AB - TaC–TaSi 2 composites were fabricated at 1700°C by an in situ reaction/hot pressing method using Ta, Si, and graphite as initial materials. TaSi 2 content was 0–100 vol%. The microstructure and mechanical properties of the composites were investigated. It was found that the relative densities of composites were above 97.5% when the volume content of TaSi 2 was above 10%. The TaC/10 vol% TaSi 2 composite presented the highest flexural strength of 376 MPa. When the TaSi 2 content was 30–50 vol%, the composites showed the highest fracture toughness of about 4.3 MP·am 1/2 . In addition, the composites could retain high Young's modulus up to at least 1525°C. DA - 2010/// PY - 2010/// DO - 10.1111/j.1744-7402.2009.02392.x VL - 7 IS - 6 SP - 697-703 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-78449266486&partnerID=MN8TOARS ER - TY - JOUR TI - A new method to improve the high-temperature mechanical properties of Ti3SiC2 by substituting Ti with Zr, Hf, or Nb AU - Wan, D.-T. AU - He, L.-F. AU - Zheng, L.-L. AU - Zhang, J. AU - Bao, Y.-W. AU - Zhou, Y.-C. T2 - Journal of the American Ceramic Society AB - Ti 3 SiC 2 shows a unique combination of the properties of both metals and ceramics. However, its stiffness and strength lose rapidly above 1050°C, which is the main obstacle for the high‐temperature application of this material. To improve the high‐temperature mechanical properties of Ti 3 SiC 2 , Zr, Hf, or Nb were used as dopants in Ti 3 (SiAl)C 2 . At room temperature, the Zr‐, Hf‐, or Nb‐doped Ti 3 (SiAl)C 2 ceramics have comparable stiffness, hardness, strength, and fracture toughness with those of Ti 3 (SiAl)C 2 . At high temperatures, however, a significant improvement in stiffness and strength has been achieved for (Ti 1− x T x ) 3 (SiAl)C 2 (T=Zr, Hf, or Nb). (Ti 1− x T x ) 3 (SiAl)C 2 can retain high degrees of stiffness and strength up to 1200°C, which is 150°C higher than those for Ti 3 (SiAl)C 2 . DA - 2010/// PY - 2010/// DO - 10.1111/j.1551-2916.2010.03637.x VL - 93 IS - 6 SP - 1749-1753 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77953098758&partnerID=MN8TOARS ER - TY - JOUR TI - Spectral analysis of turbulence based on the DNS of a channel flow AU - Bolotnov, Igor A. AU - Lahey, Richard T., Jr. AU - Drew, Donald A. AU - Jansen, Kenneth E. AU - Oberai, Assad A. T2 - Computers & Fluids AB - The development and assessment of spectral turbulence models requires knowledge of the spectral turbulent kinetic energy distribution as well as an understanding of the terms which determine the energy distribution in physical and wave number space. Direct numerical simulation (DNS) of turbulent channel flow yields numerical “data” that can be, and was, analyzed using a spatial Fast Fourier Transform (FFT) to obtain the various spectral turbulent kinetic energy balance terms, including the production, dissipation, diffusion, and the non-linear convective transfer terms. DA - 2010/4// PY - 2010/4// DO - 10.1016/j.compfluid.2009.11.001 VL - 39 IS - 4 SP - 640-655 J2 - Computers & Fluids LA - en OP - SN - 0045-7930 UR - http://dx.doi.org/10.1016/j.compfluid.2009.11.001 DB - Crossref KW - Turbulent channel flow KW - Spectral analysis KW - Turbulent kinetic energy KW - DNS ER - TY - JOUR TI - Variation of electric shielding on virtual Frisch-grid detectors AU - Polack, J.K. AU - Hirt, M. AU - Sturgess, J. AU - Sferrazza, N.D. AU - Bolotnikov, A.E. AU - Babalola, S. AU - Camarda, G.S. AU - Cui, Y. AU - Egarievwe, S.U. AU - Fochuk, P.M. AU - Gul, R. AU - Hossain, A. AU - Kim, K. AU - Kopach, O.V. AU - Marchini, L. AU - Yang, G. AU - Xu, L. AU - James, R.B. T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment AB - Because of the low mobility of holes, CdZnTe (CZT) detectors operate as electron-transport-only type devices whose particular geometrical parameters and contacts configurations are specially chosen to minimize the contribution of uncollected holes into the output signal amplitudes (induction effect). Several detector configurations have been proposed to address this problem. One of them employs a large geometrical aspect ratio, parallelepiped-shaped crystal with two planar contacts on the top and bottom surfaces (anode and cathode) and an additional shielding electrode placed on a crystal’s side to create the virtual Frisch-grid effect. We studied the effect of the shielding electrode length, as well as its location, on the responses of 6×6×15 mm3 virtual Frisch-grid detectors. We found that the length of the shielding electrode placed next to the anode can be reduced to 5 mm with no adverse effects on the device performance. Meanwhile, this allows for charge loss correction by reading the cathode signals. DA - 2010/9// PY - 2010/9// DO - 10.1016/j.nima.2010.05.035 VL - 621 IS - 1-3 SP - 424-430 J2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment LA - en OP - SN - 0168-9002 UR - http://dx.doi.org/10.1016/j.nima.2010.05.035 DB - Crossref KW - CdZnTe KW - Virtual Frisch-grid detectors KW - Gamma-ray detectors ER - TY - JOUR TI - Extended defects in CdZnTe crystals: Effects on device performance AU - Hossain, A. AU - Bolotnikov, A.E. AU - Camarda, G.S. AU - Cui, Y. AU - Yang, G. AU - Kim, K-H. AU - Gul, R. AU - Xu, L. AU - James, R.B. T2 - Journal of Crystal Growth AB - We explored some unique defects in a batch of cadmium zinc telluride (CdZnTe) crystals, along with dislocations and Te-rich decorated features, revealed by chemical etching. We extensively investigated these distinctive imperfections in the crystals to identify their origin, dimensions, and distribution in the bulk material. We estimated that these features ranged from 50 to 500 μm in diameter, and their depth was about ∼300 μm. The density of these features ranged between 2×102 and 1×103 per cm3. We elaborated a model of them and projected their effect on charge collection and spectral response. In addition, we fabricated detectors with these defective crystals and acquired fine details of charge-transport phenomena over the detectors’ volume using a high-spatial resolution (25 μm) X-ray response mapping technique. We related the results to better understand the defects and their influence on the charge-transport properties of the devices. The role of the defects was identified by correlating their signatures with the findings from our theoretical model and our experimental data. DA - 2010/5// PY - 2010/5// DO - 10.1016/j.jcrysgro.2010.03.005 VL - 312 IS - 11 SP - 1795-1799 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2010.03.005 DB - Crossref KW - Defects KW - Etching KW - Semiconducting II-VI materials ER - TY - JOUR TI - Defect levels and thermomigration of Te precipitates in CdZnTe:Pb AU - Kim, K.H. AU - Gul, R. AU - Carcelén, V. AU - Bolotinkov, A.E. AU - Carmarda, G.S. AU - Yang, G. AU - Hossain, A. AU - Cui, Y. AU - James, R.B. AU - Hong, J. AU - Kim, S.U. T2 - Journal of Crystal Growth AB - Semi-insulating Cd0.9Zn0.1Te:Pb crystals were grown by the vertical Bridgman method. Measurements of the current deep level transient spectroscopy (I-DLTS) revealed three trap levels in this material. Unlike other compensating dopants, CdZnTe:Pb samples do not show any Cd-vacancies defects and A-center levels. We subjected them to temperature-gradient annealing in Cd overpressure at 490–717 °C, and recorded an exponential relationship between the annihilation time of Te precipitates and the annealing temperature. The energy resolution of an annealed CdZnTe:Pb detector, tested using a 137Cs radioactive source, gave an energy resolution of 2.5%. DA - 2010/3// PY - 2010/3// DO - 10.1016/j.jcrysgro.2009.11.069 VL - 312 IS - 6 SP - 781-784 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2009.11.069 DB - Crossref KW - Doping KW - Point defects KW - Bridgman technique KW - Cadmium compounds KW - Semiconducting II-VI materials ER - TY - JOUR TI - Effective Surface Passivation of CdMnTe Materials AU - Kim, K.H. AU - Carcelén, V. AU - Bolotnikov, A.E. AU - Camarda, G.S. AU - Gul, R. AU - Hossain, A. AU - Yang, G. AU - Cui, Y. AU - James, R.B. T2 - Journal of Electronic Materials DA - 2010/2/13/ PY - 2010/2/13/ DO - 10.1007/S11664-010-1090-Y VL - 39 IS - 7 SP - 1015-1018 J2 - Journal of Elec Materi LA - en OP - SN - 0361-5235 1543-186X UR - http://dx.doi.org/10.1007/S11664-010-1090-Y DB - Crossref KW - CdMnTe KW - CdMnTe:In KW - passivation KW - leakage current KW - ammonium sulfide KW - ammonium fluoride KW - tellurium oxide KW - surface recombination KW - charge-collection efficiency ER - TY - JOUR TI - Investigation of Cadmium Manganese Telluride Crystals for Room-Temperature Radiation Detection AU - Yang, G. AU - Bolotnikov, A. E. AU - Li, L. AU - Camarda, G. S. AU - Cui, Y. AU - Hossain, A. AU - Kim, K. AU - Carcelen, V. AU - Gul, R. AU - James, R. B. T2 - Journal of Electronic Materials DA - 2010/1/7/ PY - 2010/1/7/ DO - 10.1007/S11664-009-1050-6 VL - 39 IS - 7 SP - 1053-1057 J2 - Journal of Elec Materi LA - en OP - SN - 0361-5235 1543-186X UR - http://dx.doi.org/10.1007/S11664-009-1050-6 DB - Crossref KW - CMT KW - synchrotron white-beam x-ray topography KW - photoluminescence spectra KW - detector response KW - twins ER - TY - JOUR TI - In Situ TEM Studies of Microstructure Evolution Under Ion Irradiation for Nuclear Engineering Applications AU - Kaoumi, D AU - Motta, AT AU - Kirk, M AU - Faney, T AU - Wirth, B AU - Bentley, J T2 - Microscopy and Microanalysis AB - Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. DA - 2010/7// PY - 2010/7// DO - 10.1017/S143192761006321X VL - 16 IS - S2 SP - 1606-1607 J2 - Microsc Microanal LA - en OP - SN - 1431-9276 1435-8115 UR - http://dx.doi.org/10.1017/S143192761006321X DB - Crossref ER - TY - JOUR TI - Application of Global Sensitivity Analysis to Nuclear Reactor Calculations AU - Espel, F. Puente AU - Tarantola, S. AU - Ghrayeb, S. AU - Ivanov, K. T2 - Procedia - Social and Behavioral Sciences AB - The studies presented in this paper, describe the application of global sensitivity analysis to the modeling of nuclear reactor physics for better model understanding. Specifically, we investigate how much criticality conditions are affected by uncertainties in various inputs, including nuclear cross-sections, at different energies, from several isotopes in the fuel, the absorber and the moderator. The sensitivity analysis uses the Sobol’ and Jansen formulas, which allow us to estimate, for each uncertain input, its main effect, its total effect (i.e. the overall effect, which includes all the interactions, at any order, with all the other uncertain inputs), and all two-way interactions among all possible pairs of uncertain inputs. The sensitivity analysis consists of a number of model simulations, which are performed using Monte Carlo code MCNP5. DA - 2010/// PY - 2010/// DO - 10.1016/j.sbspro.2010.05.199 VL - 2 IS - 6 SP - 7726-7727 J2 - Procedia - Social and Behavioral Sciences LA - en OP - SN - 1877-0428 UR - http://dx.doi.org/10.1016/j.sbspro.2010.05.199 DB - Crossref ER - TY - JOUR TI - Transport model based on three-dimensional cross-section generation for TRIGA core analysis AU - Kriangchaiporn, N. AU - Ivanov, K. AU - Haghighat, A. AU - Sears, C.F. T2 - Annals of Nuclear Energy AB - Three-dimensional (3-D) transport model for the Pennsylvania State University Breazeale Reactor (PSBR) core analysis has been developed based on the discrete ordinates (Sn) method. The effective fine- and broad-group structures for the TRIGA cross-section libraries were selected based on CPXSD (Contributon and Point-wise Cross-Section Driven) methodology. The study shows results of the following effective broad-group energy structures – a 12-group structure in 2-D geometry vs. a 26-group structure in 3-D geometry. Different 3-D pin/core configurations were used to verify and validate the selected effective group structures. The results agree with continuous energy cross-section Monte Carlo calculations for eigenvalues and normalized pin-power distributions, which are used as a reference in this research. DA - 2010/9// PY - 2010/9// DO - 10.1016/j.anucene.2010.04.011 VL - 37 IS - 9 SP - 1254-1260 J2 - Annals of Nuclear Energy LA - en OP - SN - 0306-4549 UR - http://dx.doi.org/10.1016/j.anucene.2010.04.011 DB - Crossref KW - TRIGA KW - Discrete ordinates KW - Cross-section generation KW - Transport calculation KW - Core analysis KW - DORT/TORT ER - TY - JOUR TI - Verification, validation and uncertainty quantification in multi-physics modeling for nuclear reactor design and safety analysis AU - Avramova, Maria N. AU - Ivanov, Kostadin N. T2 - Progress in Nuclear Energy AB - The qualification procedure of coupled multi-physics code systems is based on the qualification framework (verification and validation) of separate physics models/codes, and includes in addition Verification and Validation (V&V) of the coupling methodologies of the different physics models. The extended verification procedure involves testing the functionality, the data exchange between different physics models, and their coupling, which is designed to model combined effects determined by the interaction of models. The extended validation procedure compares the predictions from coupled multi-physics code systems to available measured data and reference results. It is important to emphasize that such validation should be based on a multi-level approach similar to the one utilized in validating coupled neutronics/thermal–hydraulics codes in international standard problems. Appropriate benchmarks have been developed in international co-operation led by the Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation and Development (OECD) that permits testing the neutronics/thermal–hydraulics coupling, and verifying the capability of the coupled codes to analyze complex transients with coupled core/plant interactions. This paper describes the above-mentioned multi-level V&V approach along with examples of the OECD benchmarks. In recent years there has been an increasing demand from nuclear research, industry, safety, and regulation for best estimate predictions to be provided with their confidence bounds. The ongoing OECD Light Water Reactor (LWR) Uncertainty Analysis in Modeling (UAM) benchmark activities contribute to establishing an unified framework to estimate safety margins supplemented by Uncertainty Quantification (UQ), which would provide more realistic, complete and logical measure of reactor safety. The paper describes the progress of the OECD LWR UAM benchmark. This activity is designed to address current regulation needs and issues related to practical implementation of risk informed regulation. Establishing such internationally accepted LWR UAM benchmark framework offers the possibility to accelerate the licensing process when using best estimate methods. DA - 2010/9// PY - 2010/9// DO - 10.1016/j.pnucene.2010.03.009 VL - 52 IS - 7 SP - 601-614 J2 - Progress in Nuclear Energy LA - en OP - SN - 0149-1970 UR - http://dx.doi.org/10.1016/j.pnucene.2010.03.009 DB - Crossref KW - Verification KW - Validation KW - Uncertainty KW - Design KW - Analysis ER - TY - JOUR TI - Electrospun ultrathin nylon fibers for protective applications AU - Vitchuli, Narendiran AU - Shi, Quan AU - Nowak, Joshua AU - McCord, Marian AU - Bourham, Mohamed AU - Zhang, Xiangwu T2 - Journal of Applied Polymer Science AB - Abstract Electrospun nylon 6 fiber mats were deposited on woven 50/50 nylon/cotton fabric with the motive of making them into protective material against submicron‐level aerosol chemical and biological threats. Polymer solution concentration, electrospinning voltage, and deposition areal densities were varied to establish the relationships of processing‐structure‐filtration efficiency of electrospun fiber mats. A high barrier efficiency of greater than 99.5% was achieved on electrospun fiber mats without sacrificing air permeability and pressure drop. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 DA - 2010/// PY - 2010/// DO - 10.1002/app.31825 VL - 116 IS - 4 SP - NA-NA J2 - J. Appl. Polym. Sci. LA - en OP - SN - 0021-8995 1097-4628 UR - http://dx.doi.org/10.1002/app.31825 DB - Crossref KW - electrospinning KW - nylon 6 KW - ultrathin fiber KW - protection KW - aerosol ER - TY - JOUR TI - Structural materials issues for the next generation fission reactors AU - Chant, I. AU - Murty, K. L. T2 - JOM DA - 2010/9// PY - 2010/9// DO - 10.1007/S11837-010-0142-3 VL - 62 IS - 9 SP - 67-74 J2 - JOM LA - en OP - SN - 1047-4838 1543-1851 UR - http://dx.doi.org/10.1007/S11837-010-0142-3 DB - Crossref ER - TY - CONF TI - Validation of the lattice physics code LANCER02 with ENDF/B-VII library AU - Mertyurek, U. AU - Palmtag, S. AU - Gert, G. AU - Finch, J. C2 - 2010/// C3 - International Conference on the Physics of Reactors 2010, PHYSOR 2010 DA - 2010/// VL - 2 SP - 1130-1139 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79952378953&partnerID=MN8TOARS ER - TY - JOUR TI - The defor-s experimental study of debris formation with corium simulant materials AU - Kudinov, P. AU - Karbojian, A. AU - Weimin, Ma. AU - Dinh, T.-N. T2 - Nuclear Technology AB - Characteristics of corium debris beds formed in a severe core melt accident are studied in the Debris Bed Formation-Snapshot (DEFOR-S) test campaign, in which superheated binary-oxidic melts (both eutectic and noneutectic compositions) as the corium simulants are discharged into a water pool. Water subcooling and pool depth are found to significantly influence the debris fragments’ morphology and agglomeration. When particle agglomeration is absent, the tests produced debris beds with porosity of ~60 to 70%. This porosity is significantly higher than the ~40% porosity broadly used in contemporary analysis of corium debris coolability in light water reactor severe accidents. The impact of debris formation on corium coolability is further complicated by debris fragments’ sharp edges, roughened surfaces, and cavities that are partially or fully encapsulated within the debris fragments. These observations are made consistently in both the DEFOR-S experiments and other tests with prototypic and simulant corium melts. Synthesis of the debris fragments from the DEFOR-S tests conducted under different melt and coolant conditions reveal trends in particle size, particle sphericity, surface roughness, sharp edges, and internal porosity as functions of water subcooling and melt composition. Qualitative analysis and discussion reaffirm the complex interplay between contributing processes (droplet interfacial instability and breakup, droplet cooling and solidification, cavity formation and solid fracture) on particle morphology and, consequently, on the characteristics of the debris beds. DA - 2010/// PY - 2010/// DO - 10.13182/NT10-A9460 VL - 170 IS - 1 SP - 219-230 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77951003760&partnerID=MN8TOARS KW - severe accident KW - debris bed KW - debris morphology ER - TY - JOUR TI - The effects of debris bed's prototypical characteristics on corium coolability in a LWR severe accident AU - Ma, Weimin AU - Dinh, Truc-Nam T2 - Nuclear Engineering and Design AB - This paper is concerned with coolability assessment of a debris bed formed in fuel coolant interactions (FCIs) during a hypothetical severe accident in a light water reactor (LWR). The focus is placed the potential effect of the bed's prototypical characteristics on its coolability, in terms of (i) porosity range, (ii) multi-dimensionality, (iii) inhomogeneity, (iv) particle morphology, and (v) heat generation method (e.g. volumetric heating vs. local heaters). The analysis results indicate availability of substantial coolability margins compared to previous assessments based on models and experiments using an idealized bed configuration (e.g. 1D homogenous debris layer). Notably, high porosity (up to 70%) of debris beds, obtained in experiments and expected to be the case of prototypical debris beds, could increase the dryout heat flux by 100% and more, depending on particle size, compared with the dryout heat flux predicted for debris beds with traditionally assumed porosity of approximately 40%. Bed inhomogeneity represented by micro-channels in a mini bed is predicted to enhance the dryout heat flux by up to ∼50%, even if the micro-channels occupy only a small volume fraction (e.g., less than 4%) of the bed. The effect of coolant side ingress into a multidimensional bed is predicted to enhance the dryout heat flux by up to 40% for the beds analyzed. DA - 2010/3// PY - 2010/3// DO - 10.1016/j.nucengdes.2009.10.026 VL - 240 IS - 3 SP - 598-608 J2 - Nuclear Engineering and Design LA - en OP - SN - 0029-5493 UR - http://dx.doi.org/10.1016/j.nucengdes.2009.10.026 DB - Crossref ER - TY - JOUR TI - An approach to numerical simulation and analysis of molten corium coolability in a boiling water reactor lower head AU - Tran, C.T. AU - Kudinov, P. AU - Dinh, T.N. T2 - Nuclear Engineering and Design AB - This paper discusses an approach for application of the computational fluid dynamics (CFD) method to support development and validation of computationally effective methods for safety analysis, on the example of molten corium coolability in a BWR lower head. The approach consists of five steps designed to ensure physical soundness of the effective method simulation results: (i) analysis and decomposition of a severe accident problem into a set of separate-effect phenomena, (ii) validation of the CFD models on relevant separate-effect experiments for the reactor prototypical ranges of governing parameters, (iii) development of effective models and closures on the base of physical insights gained from relevant experiments and CFD simulations, (iv) using data from the integral experiments and CFD simulations performed under reactor prototypic conditions for validation of the effective model with quantification of uncertainty in the prediction results and (v) application of the computationally effective model to simulate and analyze the severe accident transient under consideration, including sensitivity and uncertainty analysis. Implementation of the approach is illustrated on a so-called effective convectivity model for simulation of turbulent natural convection heat transfer and phase changes in a decay-heated corium pool. It is shown that detailed information obtained from the CFD simulations are instrumental to ensure the effective models capture safety-significant local phenomena, e.g. the enhanced downward heat flux in the vicinity of a cooled control rod guide tube. DA - 2010/9// PY - 2010/9// DO - 10.1016/j.nucengdes.2009.11.029 VL - 240 IS - 9 SP - 2148-2159 J2 - Nuclear Engineering and Design LA - en OP - SN - 0029-5493 UR - http://dx.doi.org/10.1016/j.nucengdes.2009.11.029 DB - Crossref ER - TY - JOUR TI - A reconstructed discontinuous Galerkin method for the compressible Navier–Stokes equations on arbitrary grids AU - Luo, Hong AU - Luo, Luqing AU - Nourgaliev, Robert AU - Mousseau, Vincent A. AU - Dinh, Nam T2 - Journal of Computational Physics AB - A reconstruction-based discontinuous Galerkin (RDG) method is presented for the solution of the compressible Navier–Stokes equations on arbitrary grids. The RDG method, originally developed for the compressible Euler equations, is extended to discretize viscous and heat fluxes in the Navier–Stokes equations using a so-called inter-cell reconstruction, where a smooth solution is locally reconstructed using a least-squares method from the underlying discontinuous DG solution. Similar to the recovery-based DG (rDG) methods, this reconstructed DG method eliminates the introduction of ad hoc penalty or coupling terms commonly found in traditional DG methods. Unlike rDG methods, this RDG method does not need to judiciously choose a proper form of a recovered polynomial, thus is simple, flexible, and robust, and can be used on arbitrary grids. The developed RDG method is used to compute a variety of flow problems on arbitrary meshes to demonstrate its accuracy, efficiency, robustness, and versatility. The numerical results indicate that this RDG method is able to deliver the same accuracy as the well-known Bassi–Rebay II scheme, at a half of its computing costs for the discretization of the viscous fluxes in the Navier–Stokes equations, clearly demonstrating its superior performance over the existing DG methods for solving the compressible Navier–Stokes equations. DA - 2010/9// PY - 2010/9// DO - 10.1016/j.jcp.2010.05.033 VL - 229 IS - 19 SP - 6961-6978 J2 - Journal of Computational Physics LA - en OP - SN - 0021-9991 UR - http://dx.doi.org/10.1016/j.jcp.2010.05.033 DB - Crossref KW - Reconstruction schemes KW - Discontinuous Galerkin methods KW - Compressible Navier-Stokes equations ER - TY - JOUR TI - Diagnostic techniques for the dynamics of a thin liquid film under forced flow and evaporating conditions AU - Gong, Shengjie AU - Ma, Weimin AU - Dinh, Truc-Nam T2 - Microfluidics and Nanofluidics DA - 2010/5/21/ PY - 2010/5/21/ DO - 10.1007/s10404-010-0626-z VL - 9 IS - 6 SP - 1077-1089 J2 - Microfluid Nanofluid LA - en OP - SN - 1613-4982 1613-4990 UR - http://dx.doi.org/10.1007/S10404-010-0626-Z DB - Crossref KW - Thin liquid film KW - Film dynamics KW - Diagnostic technique KW - Confocal optical sensor KW - Micro-conductive probe ER - TY - PAT TI - Plasma Control Using Dual Cathode Frequency Mixing AU - C, Shannon Steven AU - S, Grimard Dennis AU - Theodoros, Panagopoulos AU - J, Hoffman Daniel AU - G, Chafin Michael AU - S, Detrick Troy AU - Alexander, Paterson AU - Jingbao, Liu AU - Taeho, Shin AU - Y, Pu Bryan C2 - 2010/11/23/ DA - 2010/11/23/ PY - 2010/11/23/ UR - https://www.lens.org/089-103-194-978-761 ER - TY - PAT TI - Method For Testing Plasma Reactor Multi-frequency Impedance Match Networks AU - C, Shannon Steven C2 - 2010/10/12/ DA - 2010/10/12/ PY - 2010/10/12/ UR - https://www.lens.org/078-180-755-189-413 ER - TY - ER - TY - JOUR TI - Emergency Situation Air Sampling AU - Hayes, Robert T2 - Radioactive Air Sampling Methods DA - 2010/10// PY - 2010/10// DO - 10.1201/b10261-22 SP - 357-367 ER - TY - JOUR TI - First principles calculations for defects in U AU - Beeler, B. AU - Good, B. AU - Rashkeev, S. AU - Deo, C. AU - Baskes, M. AU - Okuniewski, M. T2 - Journal of Physics Condensed Matter AB - Uranium (U) exhibits a high temperature body-centered cubic (bcc) allotrope that is often stabilized by alloying with transition metals such as Zr, Mo, and Nb for technological applications. One such application involves U–Zr as nuclear fuel, where radiation damage and diffusion (processes heavily dependent on point defects) are of vital importance. Several systems of U are examined within a density functional theory framework utilizing projector augmented wave pseudopotentials. Two separate generalized gradient approximations of the exchange-correlation are used to calculate defect properties and are compared. The bulk modulus, the lattice constant, and the Birch–Murnaghan equation of state for the defect free bcc uranium allotrope are calculated. Defect parameters calculated include energies of formation of vacancies in the α and γ allotropes, as well as self-interstitials, Zr interstitials, and Zr substitutional defects for the γ allotrope. The results for vacancies agree very well with experimental and previous computational studies. The most probable self-interstitial site in γ-U is the ⟨110⟩ dumbbell, and the most probable defect location for dilute Zr in γ-U is the substitutional site. This is the first detailed study of self-defects in the bcc allotrope of U and also the first comprehensive study of dilute Zr defects in γ-U. DA - 2010/// PY - 2010/// DO - 10.1088/0953-8984/22/50/505703 VL - 22 IS - 50 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-78649825146&partnerID=MN8TOARS ER - TY - CONF TI - Sterilization and surface decontamination by a novel VHF-CCP AU - Stapelmann, Katharina AU - Bibinov, Nikita AU - Denis, Benjamin AU - Semmler, Egmont AU - Awakowicz, Peter AB - Summary form only given. The application of low pressure plasma discharges for sterilization of medical instruments is an upcoming alternative to common sterilization methods, due to the variety of drawbacks, e.g. high temperature, toxic chemical agents, or the inability to sterilize and remove pathogenic material, commonly used methods are associated with. Plasma sterilization offers a highly effective, low temperature sterilization and decontamination process with a reduced process time.The capabilities of plasma treatment have been demonstrated in several laboratory setups1"3. Based on these experiences, a novel setup has been developed. It is realized as capacitively coupled plasma discharge powered by an oscillator power source in the variable frequency range between 76 and 80 MHz. The setup is designed to meet industrial needs. The discharge chamber is shaped like a drawer and composed of PEEK, a high-performance plastic. This leads to an easy handling sterilization process uncomplicated for application. Optical emission spectroscopy was performed to obtain detailed information about the plasma parameters and to optimize the plasma for sterilization purpose. Microbiological tests as well as protein removal tests are going to be presented. C2 - 2010/6// C3 - 2010 Abstracts IEEE International Conference on Plasma Science DA - 2010/6// DO - 10.1109/plasma.2010.5534056 SP - 1 pp. PB - Institute of Electrical & Electronics Engineers (IEEE) UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=INSPEC&KeyUT=INSPEC:11486060&KeyUID=INSPEC:11486060 ER - TY - JOUR TI - Inactivation of Bacteria and Biomolecules by Low-Pressure Plasma Discharges AU - Keudell, A. AU - Awakowicz, P. AU - Benedikt, J. AU - Raballand, V. AU - Yanguas-Gil, A. AU - Opretzka, J. AU - Floetgen, C. AU - Reuter, R. AU - Byelykh, L. AU - Halfmann, H. AU - Stapelmann, K. AU - Denis, B. AU - Wunderlich, J. AU - Muranyi, P. AU - Rossi, F. AU - Kylian, O. AU - Hasiwa, N. AU - Ruiz, A. AU - Rauscher, H. AU - Sirghi, L. AU - Comoy, E. AU - Dehen, C. AU - Challier, L. AU - Deslys, J. P. T2 - PLASMA PROCESSES AND POLYMERS AB - Abstract The inactivation of bacteria and biomolecules using plasma discharges were investigated within the European project BIODECON. The goal of the project was to identify and isolate inactivation mechanisms by combining dedicated beam experiments with especially designed plasma reactors. The plasma reactors are based on a fully computer‐controlled, low‐pressure inductively‐coupled plasma (ICP). Four of these reactors were built and distributed among the consortium, thereby ensuring comparability of the results between the teams. Based on this combined effort, the role of UV light, of chemical sputtering (i.e. the combined impact of neutrals and ions), and of thermal effects on bacteria such as Bacillus atrophaeus , Aspergillus niger , as well as on biomolecules such as LPS, Lipid A, BSA and prions have been evaluated. The particle fluxes emerging from the plasmas are quantified by using mass spectrometry, Langmuir probe measurements, retarding field measurements and optical emission spectroscopy. The effects of the plasma on the biological systems are evaluated using atomic force microscopy, ellipsometry, electrophoresis, specially‐designed western blot tests, and animal models. A quantitative analysis of the plasma discharges and the thorough study of their effect on biological systems led to the identification of the different mechanisms operating during the decontamination process. Our results confirm the role of UV in the 200–250 nm range for the inactivation of micro‐organisms and a large variability of results observed between different strains of the same species. Moreover, we also demonstrate the role of chemical sputtering corresponding to the synergism between ion bombardment of a surface with the simultaneous reaction of active species such as O, O 2 or H. Finally, we show that plasma processes can be efficient against different micro‐organisms, bacteria and fungi, pyrogens, model proteins and prions. The effect of matrices is described, and consequences for any future industrial implementation are discussed. magnified image DA - 2010/3/22/ PY - 2010/3/22/ DO - 10.1002/ppap.200900121 VL - 7 IS - 3-4 SP - 327-352 SN - 1612-8869 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000276547700018&KeyUID=WOS:000276547700018 KW - sterilization KW - plasma treatment KW - low-pressure discharges KW - bacterial spores KW - proteins ER - TY - JOUR TI - Elimination of Pathogenic Biological Residuals by Means of Low-Pressure Inductively Coupled Plasma Discharge AU - Kylián, Ondřej AU - Rauscher, Hubert AU - Ruiz, Ana AU - Denis, Benjamin AU - Stapelmann, Katharina AU - Rossi, François T2 - Industrial Plasma Technology AB - This chapter contains sections titled: Introduction Experimental Results Conclusions Acknowledgments References DA - 2010/3/10/ PY - 2010/3/10/ DO - 10.1002/9783527629749.ch15 VL - 3 SP - 193-199 ER - TY - JOUR TI - Creep behavior of ultra-fine grained Zn-4.5Al AU - Gobien, J. M. AU - Murty, K. L. AU - Scattergood, R. O. AU - Goodwin, F. AU - Koch, C. C. T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - Creep tests were performed at 295 and 373 K on a cryogenically ball-milled Zn–4.5Al alloy. Creep tests on the as-milled microstructure having an average grain size of 260 nm showed clear signs of a threshold stress. The same material after a targeted heat treatment showed no signs of a threshold stress for the same alloy with an average grain size of 510 nm. In both cases stress exponent (n) values close to 1 and activation energies close to that of grain boundary diffusion were noted. Potential causes of the threshold stress are proposed as being a nanocrystalline oxide dispersion or non-uniform solute segregation, each of which could potentially interfere with grain boundary vacancy transfer mechanisms. DA - 2010/10/25/ PY - 2010/10/25/ DO - 10.1016/j.msea.2010.08.020 VL - 527 IS - 27-28 SP - 7382-7386 SN - 1873-4936 KW - Zinc KW - Coble creep KW - Impression creep KW - Threshold stress ER - TY - JOUR TI - Understanding creep in nanocrystalline materials AU - Gollapudi, S. AU - Rajulapati, K. V. AU - Charit, I. AU - Youssef, K. M. AU - Koch, C. C. AU - Scattergood, R. O. AU - Murty, K. L. T2 - TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS DA - 2010/4// PY - 2010/4// DO - 10.1007/s12666-010-0050-9 VL - 63 IS - 2-3 SP - 373-378 SN - 0975-1645 KW - nanocrystalline materials KW - coble creep KW - grain growth KW - impression creep ER - TY - JOUR TI - On the Degradation of Cell-Centered Diffusive Preconditioners for Accelerating S-N Transport Calculations in the Periodic Horizontal Interface Configuration AU - Rosa, Massimiliano AU - Azmy, Yousry Y. AU - Morel, Jim E. T2 - NUCLEAR SCIENCE AND ENGINEERING AB - We investigate the degraded effectiveness of diffusion-based acceleration schemes in terms of the adjacent-cell preconditioner (AP) in a periodically heterogeneous limit devised for the two-dimensional (2-D) periodic horizontal interface (PHI) configuration. Specifically, we demonstrate that the diffusive low-order operator employed in the AP scheme lacks the structure of the integral transport operator in the above asymptotic limit since it (1) ignores cross-derivative coupling and (2) incorrectly estimates the strength of intra-layer coupling in the optically thin layers. In order to prove propositions 1 and 2, we derive expressions for the elements of the matrix representing a certain angular (SN) and spatially discretized form of the 2-D neutron transport integral operator. This is the transport operator that produces the full scalar flux solution if it is directly inverted on the once-collided particle source. The properties of this operator’s elements are then investigated in the asymptotic limit for PHI. The results of the asymptotic analysis point to a sparse but nonlocal matrix structure due to long-range coupling of a cell’s average flux with its neighboring cells, independent of the distance between the cells in the spatial mesh. In particular, for a cell in a thin layer, cross-derivative coupling of the cell’s flux to its diagonal neighbors is of the same asymptotic order as self-coupling and coupling with its north/south Cartesian neighbors. Similarly, its coupling with the fluxes in the same thin layer is of the same order, independent of the distance between the cells in the layer, as the coupling with the east/west Cartesian neighbors.We also show that modifying the standard diffusion-based AP can lead to effective acceleration in PHI. Specifically, we devise three novel acceleration schemes, named APB, Optimized-AP (OAP), and Hybrid-AP (HAP), obtained by modifying the original AP formalism in 2-D. In the APB the five-point AP operator is extended to a nine-point stencil that accounts for cross-derivative coupling by including the matrix elements of the integral transport operator B, which couple a cell-averaged scalar flux to its first diagonal neighbors. In the OAP the five-point stencil of the original AP operator is retained while optimizing the value of the elements in the preconditioner that affect the coupling of a cell with its east/west Cartesian neighbors. Specifically, the optimum elements are obtained by minimizing the iteration’s spectral radius and offer a more correct estimate of the strength of intra-layer coupling in a thin layer. Finally, the nine-point HAP operator represents a “hybrid” of the APB and OAP approaches, in the sense that the spectral properties of the optimized five-point OAP are further improved via the inclusion of cross-derivative terms. Fourier analysis of the novel acceleration schemes indicates that robustness of the accelerated iterations can be recovered, in spite of sharp material discontinuities, by accounting for cross-derivative coupling and by optimizing the preconditioner elements. The new acceleration schemes have also been implemented in a 2-D transport code, and numerical tests successfully verify the predictions of the Fourier analysis. However, it is important to emphasize that the modifications attempted in this work are specific to the selected asymptotic limit for PHI and do not translate into new low-order operators for the general heterogeneous-material case. Rather, the above modified operators suggest that it may be possible to eventually derive such a general low-order unconditionally robust operator. DA - 2010/11// PY - 2010/11// DO - 10.13182/nse09-69 VL - 166 IS - 3 SP - 218-238 SN - 0029-5639 ER - TY - JOUR TI - Newtonian viscous creep in metals AU - Murty, K. Linga AU - Gollapudi, S. AU - Charit, I. T2 - TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS DA - 2010/4// PY - 2010/4// DO - 10.1007/s12666-010-0012-2 VL - 63 IS - 2-3 SP - 85-91 SN - 0975-1645 KW - Newtonian viscous creep KW - Nabarro-Herring KW - Coble KW - Harper-Dorn KW - diffusion ER - TY - JOUR TI - Model-based calculations of the probability of a country's nuclear proliferation decisions AU - Li, Jun AU - Yim, Man-Sung AU - McNelis, David N. T2 - PROGRESS IN NUCLEAR ENERGY AB - Abstract This paper presents an attempt to project a country’s nuclear proliferation-related behaviors by using quantitative models with the use of open source information. The approach is based on the combined use of data on a country’s economic status, security environment, political development, nuclear technological capability, and commitment to nuclear nonproliferation. Projections of country’s proliferation-related behaviors were made by using the multinomial logit regression and the Weibull and Cox event history modeling for 189 countries. Results from the developed models were compared with the historical records from 1945 through 2000 with respect to “explore”, “pursue”, and “acquire” decisions. Overall, this study indicated that quantitative models could be useful in providing warnings against potential nuclear proliferation attempts. Key variables of importance in quantitative modeling of proliferation-related behaviors were identified and discussed. DA - 2010/11// PY - 2010/11// DO - 10.1016/j.pnucene.2010.07.001 VL - 52 IS - 8 SP - 789-808 SN - 0149-1970 KW - Nuclear proliferation decisions KW - Projecting proliferation decisions KW - Statistical models KW - Security environment and economic development KW - Nuclear technological capability KW - Open source information ER - TY - JOUR TI - Reanalysis of Recent Neutron Diffusion and Transmission Measurements in Nuclear Graphite AU - Gould, C. R. AU - Hawari, A. I. AU - Sharapov, E. I. T2 - NUCLEAR SCIENCE AND ENGINEERING AB - We revisit the determination by Bowman et al. of unusual neutron transport characteristics for a newly fabricated form of graphite [Nucl. Sci. Eng., 159, 182 (2008); Nucl. Sci. Eng., 161, 68 (2009)]. From MCNP modeling and consideration of data from other experiments, we determine revised values for the neutron transport parameters of this graphite. Our reanalysis gives a coherent scattering cross section σcoh ˜ 4 b at 50 meV, a small-angle neutron scattering cross section σsans ˜ 11 to 13 b at 1 meV, and an effective capture cross section σa = 5.8 ± 0.5 mb. Scaled to a graphite reference density of 1.60 g/cm3, we find a diffusion coefficient D̄ = 0.94 ± 0.03 cm and a diffusion length L = 47.7 ± 3.7 cm. Apart from the somewhat larger values of σa and D̄, these are not untypical parameters for graphite. Based on our investigation, the recent experiments and analysis of Bowman et al. do not give evidence for different transport properties for this newly fabricated graphite. DA - 2010/6// PY - 2010/6// DO - 10.13182/nse09-48 VL - 165 IS - 2 SP - 200-209 SN - 0029-5639 ER - TY - JOUR TI - Nonlinear Weighted Flux Methods for Particle Transport Problems in Two-Dimensional Cartesian Geometry AU - Roberts, Loren AU - Anistratov, Dmitriy Y. T2 - NUCLEAR SCIENCE AND ENGINEERING AB - A family of nonlinear weighted flux (NWF) methods for solving the transport equation in two-dimensional (2-D) Cartesian geometry is considered. The low-order equations of these methods are defined by means of special linear-fractional factors that are determined by the high-order transport solution. An asymptotic diffusion limit analysis is performed on methods with a general weight function. The analysis revealed conditions on the weight necessary for an accurate approximation of the diffusion equation in this limit. We study methods with weights defined by linear and bilinear functions of directional cosines. As a result, we developed 2-D NWF methods formulated with the low-order equations that give rise to the diffusion equation in optically thick diffusive regions if their factors are calculated by means of the leading-order transport solution. The inherent asymptotic boundary conditions for the NWF methods are analyzed. Numerical results are presented to confirm theoretical results and demonstrate performance of the proposed methods. DA - 2010/6// PY - 2010/6// DO - 10.13182/nse08-48 VL - 165 IS - 2 SP - 133-148 SN - 0029-5639 ER - TY - JOUR TI - Application of Active NPC Converter on Generator Side for MW Direct-driven Wind Turbine AU - Li, Jun AU - Huang, Alex Q. AU - Bhattacharya, Subhashish AU - Jing, Wei T2 - 2010 TWENTY-FIFTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC) AB - 3L-NPC topology is usually used in MW wind turbine (WT) systems with full-scale converter configuration. However, due to its drawback of unequal device loss distribution, the converter rated power, and thus the WT unit capacity is limited. Moreover, in cased of device failure in generator converter, in order to protect the WT system, the converter has to shut down to disconnect the WT. This paper presents the application of active NPC (ANPC) converter on generator side. Loss-balancing schemes are discussed, and thermal performance of NPC and ANPC generator converters are compared. Also, the control scheme of generator converter under single device failure condition is proposed to maintain the WT in service and continue to provide real power, which brings benefits in the reliable and economic aspects to the WT system. Simulation results are provided to validate the proposed control methods. DA - 2010/// PY - 2010/// DO - 10.1109/apec.2010.5433381 SP - 1010-1017 SN - 1048-2334 ER - TY - JOUR TI - The classical nature of thermal conduction in nanofluids AU - Eapen, J. AU - Rusconi, R. AU - Piazza, R. AU - Yip, S. T2 - Journal of Heat Transfer DA - 2010/// PY - 2010/// VL - 132 IS - 10 ER - TY - JOUR TI - Terminal Alkynes as an Ink or Background SAM in Replacement Lithography: Adventitious versus Directed Replacement AU - Tucker, Eric Z. AU - Gorman, Christopher B. T2 - LANGMUIR AB - Self-assembled monolayers (SAMs) comprised from n-alkanethiols and terminal alkynes were subjected to solutions containing ferrocene-terminated thiol, thioacetate, and terminal alkyne. The rate and extent of chemical exchange were monitored by scanning tunneling microscopy (STM). In several cases, a rate constant for exchange could be obtained by fitting to a model for exchange. In each case where this could be accomplished, a different rate model gave the best fit to the data, suggesting that the mechanism of exchange depended on either or both the original SAM and the incoming molecule. In scenarios where the rate of exchange was slow, directed exchange was accomplished via STM tip-induced lithographic patterning (replacement lithography). The extent of exchange was independent of the incoming molecule, suggesting that tip-induced desorption was the limiting factor in this process. DA - 2010/9/21/ PY - 2010/9/21/ DO - 10.1021/la101676h VL - 26 IS - 18 SP - 15027-15034 SN - 0743-7463 ER - TY - JOUR TI - Materials for next-generation nuclear plants: Objectives and challenges AU - Murty, K. L. T2 - JOM: the Journal of the Minerals, Metals & Materials Society DA - 2010/// PY - 2010/// DO - 10.1007/s11837-010-0139-y VL - 62 IS - 9 SP - 60-61 ER - TY - JOUR TI - Irradiation Induced Creep of Graphite AU - Burchell, T. D. AU - Murty, K. L. AU - Eapen, J. T2 - JOM DA - 2010/9// PY - 2010/9// DO - 10.1007/s11837-010-0145-0 VL - 62 IS - 9 SP - 93-99 SN - 1543-1851 ER - TY - JOUR TI - X-ray structure of the metcyano form of dehaloperoxidase from Amphitrite ornata: Evidence for photoreductive dissociation of the iron-cyanide bond AU - Serrano, V. S. AU - Davis, M. F. AU - Gaff, J. F. AU - Zhang, Q. AU - Chen, Z. AU - D'Antonio, E. L. AU - Bowden, E. F. AU - Rose, R. AU - Franzen, S. T2 - Acta Crystallographica. Section D, Biological Crystallography DA - 2010/// PY - 2010/// VL - 66 SP - 770-782 ER - TY - JOUR TI - Creep in nanocrystalline materials: Role of stress assisted grain growth AU - Gollapudi, S. AU - Rajulapati, K. V. AU - Charit, I. AU - Koch, C. C. AU - Scattergood, R. O. AU - Murty, K. L. T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - To date, only a limited number of creep studies have been carried out on nanocrystalline materials. These studies have remained largely inconclusive in establishing the creep mechanisms in nanocrystalline materials. The stress exponent and activation energy values obtained for nanocrystalline materials do not correlate well with conventional, well established creep models. Furthermore, discrepancy between experimentally determined deformation rates and theoretical predictions suggests that an entirely new mechanism of creep may be operational in these materials. Thus, this work aims to develop an understanding of the creep behavior of nanocrystalline materials by considering a stress assisted grain growth mechanism that has been recently identified in these materials. A model that provides an understanding of some observations made in creep literature has been developed. Impression creep data obtained from tests on nanocrystalline aluminum agree with model predictions. DA - 2010/8/20/ PY - 2010/8/20/ DO - 10.1016/j.msea.2010.05.048 VL - 527 IS - 21-22 SP - 5773-5781 SN - 1873-4936 KW - Grain growth KW - Grain boundaries KW - Nanostructured alloys KW - Aluminum alloys KW - Mechanical alloying ER - TY - JOUR TI - The sensitivity of fuel cycle performance to separation efficiency AU - Li, Jun AU - Scopatz, Anthony AU - Yim, Man-Sung AU - Schneider, Erich T2 - NUCLEAR ENGINEERING AND DESIGN AB - Reprocessing separation efficiency is a major design variable in the implementation of advanced fuel cycles as it affects waste disposal requirements, fuel fabrication, system economics, and other fuel cycle system characteristics. Using a newly developed, physics-based integrated fuel cycle systems analysis model, this study investigated the impact of varying reprocessing separation efficiencies on fuel cycle cost (FCC), proliferation resistance and repository impact. Repository impact was captured by the disposal facility capacity governed by thermal output, the projected dose rate, mass inventory, and waste toxicity index. The coupled systems analysis model included fast reactor simulation tool to analyze the depletion in the fast reactor and the requirements for the fresh fuel in transient and equilibrium states. In this calculation, the feedback between separation efficiencies and fresh and discharged fuel compositions was dynamically accounted for. The new systems model was benchmarked against published results and used to investigate a single-tier nuclear fuel cycle scenario in which light water reactors (LWRs) and 0.5 transuranic (TRU) conversion ratio (CR) sodium-cooled fast reactors are deployed in an equilibrium that results in zero net TRU production. The results indicated that fuel cycle system performance is significantly affected by the changes in partitioning strategies and elemental separation efficiency in reprocessing plants. Moreover, the effect of varying separation efficiencies on reactor performance, fuel cycle mass balances and economic performance are discussed. DA - 2010/3// PY - 2010/3// DO - 10.1016/j.nucengdes.2009.02.004 VL - 240 IS - 3 SP - 511-523 SN - 0029-5493 ER - TY - JOUR TI - Semi-empirical modeling of gamma-ray density logs with the possibility of obtaining more information AU - Li, Fusheng AU - Gardner, Robin P. T2 - APPLIED RADIATION AND ISOTOPES AB - A semi-empirical model based on the forward scatter principle has been devised for describing the gamma-ray density log for oil well logging. This approach is significantly different from the existing primarily empirical model and approach that is presently used for this purpose. It offers the possibility of providing a more fundamental and accurate basis for log interpretation since the natural parameters used in this approach are also significantly different and more fundamental than the ones presently in use. DA - 2010/// PY - 2010/// DO - 10.1016/j.apradiso.2009.10.047 VL - 68 IS - 4-5 SP - 936-940 SN - 0969-8043 ER - TY - JOUR TI - On the future of Monte Carlo simulation for nuclear logs AU - Gardner, Robin P. AU - Sood, Avneet T2 - APPLIED RADIATION AND ISOTOPES AB - The oil and oil well logging companies have long been innovators in many technologies that are used in oil well logging. This includes the development and use of radiation detection equipment in the harsh environment of oil wells. It also certainly includes the use of Monte Carlo simulation in the study, optimum design, and calculation of corrections and correction factors for the inverse logging problem. This latter area is the subject of this paper. Past milestones in this area are discussed along with those of the present and future work. The perspective is from the viewpoint of the authors. DA - 2010/// PY - 2010/// DO - 10.1016/j.apradiso.2009.10.021 VL - 68 IS - 4-5 SP - 932-935 SN - 0969-8043 ER - TY - JOUR TI - On replacing Am-Be neutron sources in compensated porosity logging tools AU - Peeples, Cody R. AU - Mickael, Medhat AU - Gardner, Robin P. T2 - APPLIED RADIATION AND ISOTOPES AB - Authors explored the direct replacement of Am-Be neutron sources in neutron porosity logging tools through Monte Carlo simulations using MCNP5. (252)Cf and electronic accelerator neutron sources based on the Deuterium-Tritium fusion reaction were considered. Between the sources, a tradeoff was noted between sensitivity to the presence of hydrogen and uncertainty due to counting statistics. It was concluded that both replacement sources as well as accelerator sources based on the Deuterium-Deuterium fusion reaction warrant further consideration as porosity log sources. DA - 2010/// PY - 2010/// DO - 10.1016/j.apradiso.2009.11.042 VL - 68 IS - 4-5 SP - 926-931 SN - 0969-8043 KW - Neutron sources KW - Monte Carlo KW - Nuclear well logging KW - (252)Cf KW - (241)Am KW - D-T KW - D-D ER - TY - JOUR TI - Electron Energy Distribution Function Extraction Using Integrated Step Function Response and Regularization Methods AU - El Saghir, A. AU - Kennedy, C. AU - Shannon, S. T2 - IEEE Transactions on Plasma Science AB - Recently, electron energy distribution function (EEDF) extraction techniques have been evaluated using regularized solutions to the integral problem. These techniques do not assume any mathematical representation of the EEDF and solve the integral problem for any function that best represents the EEDF. Also, unlike the more widely used point-by-point extraction of the second-derivative relationship, the integrated relationship between electron current and the EEDF is used, instead of a relatively small fraction of the integrated data in the point-by-point method. In this paper, the electron current for an arbitrary distribution function is derived, assuming that the distribution is a sum of step functions representing such a function. This technique for EEDF extraction is validated by adding noise to numerically generated data and using a regularized least squares (RLS) method to calculate the original function by solving for the individual step function contribution to the total electron current. Comparisons are then made between the expected and the reconstructed solution to evaluate its accuracy with respect to EEDF reconstruction and integrated normalization of the electron density. DA - 2010/2// PY - 2010/2// DO - 10.1109/tps.2009.2036013 VL - 38 IS - 2 SP - 156-162 J2 - IEEE Trans. Plasma Sci. OP - SN - 0093-3813 1939-9375 UR - http://dx.doi.org/10.1109/TPS.2009.2036013 DB - Crossref KW - Druyvesteyn KW - electron energy distribution function (EEDF) KW - Tikhonov regularization ER - TY - JOUR TI - A novel ultra-light structure for radiation shielding AU - Xu, Siqi AU - Bourham, Mohamed AU - Rabiei, Afsaneh T2 - MATERIALS & DESIGN AB - A new ultra-light structure based on the application of open-cell metal foams has been designed and investigated to determine its ability for attenuation of γ-rays and thermal neutrons. Open-cell metal foam, a unique class of material, has been employed in the structure and is studied in this work where radiation attenuation abilities of foams and foams filled with water and borated water have been compared with bulk Aluminum. The γ-ray attenuation measurements were performed using γ-ray at 0.662, 1.173 and 1.332 MeV photon energies and thermal neutron attenuation measurements were conducted using a polyenergetic thermal neutron beam. The results show that the metallic foam by itself attenuates less γ-ray as compared to bulk material, while the mass attenuation coefficients of foams filled with water is higher than that of bulk metals. The thermal neutron experiment, on the other hand, has shown a dramatic attenuation improvement in foams filled with water and particularly with borated water as compared to bulk metal and foam. DA - 2010/4// PY - 2010/4// DO - 10.1016/j.matdes.2009.11.011 VL - 31 IS - 4 SP - 2140-2146 SN - 1873-4197 ER -