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Assessement of the JEFF-3.1.1 Neutron Data Library for FOR CSE of LWR Fuel Storage Pools
Edwin Kolbe,Alexander Vasiliev,Hakim Ferroukhi 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
A methodology for criticality safety evaluations (CSE) of light water reactor (LWR) compact storage pools and transport casks based on the Monte Carlo code MCNPX-2.5.0 was recently established at PSI. Validation calculations were performed applying a suite of 15 low-enriched thermal compound uranium and 4 mixed plutonium uranium thermal compound benchmarks extracted from the International Handbook of Evaluated Criticality Safety Benchmark Experiments. In a first part of this paper, the same validation suite, comprising in total 149 benchmark cases, is analyzed with the latest release of the JEFF-3.1.1 nuclear data library. The resulting bias is compared to the ones obtained previously with the ENDF/B-VII.0, JEFF-3.1 and JENDL-3.3 libraries. Secondly, in licensing-related studies for a new PWR commercial wet storage pool, a noticeable sensitivity upon the employed thermal neutron scattering S(α,β) matrix data was observed for water reflected configurations. By performing trend analyses with respect to the magnitude of the thermal flux for a selected subset of benchmark cases, various parameterizations of S(α,β) could be assessed including the one in JEFF-3.1.1. Finally, the benefits from applying several cross-section libraries in CSE will be pointed out.
Axisymmetric bending of a circular plate with stiff edge on a soft FGM layer
Sergey S. Volkov,Alexander N. Litvinenko,Sergey M. Aizikovich,Yun-Che Wang,Andrey S. Vasiliev 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.2
A circular plate with constant thickness, finite radius and stiff edge lying on an elastic halfspace is considered. The half-space consists of a soft functionally graded (FGM) layer with arbitrary varying elastic properties and a homogeneous elastic substrate. The plate bends under the action of arbitrary axisymmetric distributed load and response from the elastic half-space. A semi-analytical solution for the problem effective in whole range of geometric (relative layer thickness) and mechanical (elastic properties of coating and substrate, stiffness of the plate) properties is constructed using the bilateral asymptotic method (Aizikovich et al. 2009). Approximated analytical expressions for the contact stresses and deflections of the plate are provided. Numerical results showing the qualitative dependence of the solution from the initial parameters of the problem are obtained with high precision.
Pressure dependence of upper critical fields in FeSe single crystals
Kang, Ji-Hoon,Jung, Soon-Gil,Lee, Sangyun,Park, Eunsung,Lin, Jiunn-Yuan,Chareev, Dmitriy A,Vasiliev, Alexander N,Park, Tuson IOP 2016 Superconductor science & technology Vol.29 No.3
<P>We investigate the pressure dependence of the upper critical fields (<I>μ</I> <SUB>0</SUB> <I>H</I> <SUB>c2</SUB>) for FeSe single crystals with pressure up to 2.57 GPa. The superconducting (SC) properties show a disparate behavior across a critical pressure where the pressure-induced antiferromagnetic phase coexists with superconductivity. The magnetoresistance for <I>H</I>//<I>ab</I> and <I>H</I>//<I>c</I> is very different: for <I>H</I>//<I>c</I>, magnetic field induces and enhances a hump in the resistivity close to the <I>T</I> <SUB>c</SUB> for pressures higher than 1.2 GPa, while it is absent for <I>H</I>//<I>ab</I>. Since the measured <I>μ</I> <SUB>0</SUB> <I>H</I> <SUB>c2</SUB> for FeSe samples is smaller than the orbital limited upper critical field <img ALIGN='MIDDLE' ALT='$({{{H}}^{{\rm{orb}}}}_{{\rm{c}}2})$' SRC='http://ej.iop.org/images/0953-2048/29/3/035007/sustaa1185ieqn1.gif'/> estimated by the Werthamer, Helfand and Hohenberg model, the Maki parameter (<I>α</I>) related to Pauli spin-paramagnetic effects is additionally considered to describe the temperature dependence of <I>μ</I> <SUB>0</SUB> <I>H</I> <SUB>c2</SUB>(<I>T</I>). Interestingly, the <I>α</I> value is hardly affected by pressure for <I>H</I>//<I>ab</I>, while it strongly increases with pressure for <I>H</I>//<I>c</I>. The pressure evolution of the <I>μ</I> <SUB>0</SUB> <I>H</I> <SUB>c2</SUB>(0) for the FeSe single crystals is found to be almost similar to that of <I>T</I> <SUB>c</SUB>(<I>P</I>), suggesting that the pressure-induced magnetic order adversely affects the upper critical fields as well as the SC transition temperature.</P>
Uma, Sitharaman,Vasilchikova, Tatyana,Sobolev, Alexey,Raganyan, Grigory,Sethi, Aanchal,Koo, Hyun-Joo,Whangbo, Myung-Hwan,Presniakov, Igor,Glazkova, Iana,Vasiliev, Alexander,Streltsov, Sergey,Zvereva, American Chemical Society 2019 Inorganic chemistry Vol.58 No.17
<P>A new oxide, sodium-iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized and structurally characterized, and its static and dynamic magnetic properties were comprehensively studied both experimentally by <I>dc</I> and <I>ac</I> magnetic susceptibility, magnetization, specific heat, electron spin resonance (ESR) and Mössbauer measurements, and theoretically by density functional calculations. The resulting single-crystal structure (<I>a</I> = 15.6991(9) Å; <I>b</I> = 5.3323 (4) Å; <I>c</I> = 10.8875(6) Å; S.G. <I>Pbna</I>) consists of edge-shared SbO<SUB>6</SUB> octahedral chains, which alternate with vertex-linked, magnetically active FeO<SUB>4</SUB> tetrahedral chains. The <SUP>57</SUP>Fe Mössbauer spectra confirmed the presence of high-spin Fe<SUP>3+</SUP> (3d<SUP><I>5</I></SUP>) ions in a distorted tetrahedral oxygen coordination. The magnetic susceptibility and specific heat data show the absence of a long-range magnetic ordering in Na<SUB>2</SUB>FeSbO<SUB>5</SUB> down to 2 K, but <I>ac</I> magnetic susceptibility unambigously demonstrates spin-glass-type behavior with a unique two-step freezing at <I>T</I><SUB>f1</SUB> ≈ 80 K and <I>T</I><SUB>f2</SUB> ≈ 35 K. Magnetic hyperfine splitting of <SUP>57</SUP>Fe Mössbauer spectra was observed below <I>T</I>* ≈ 104 K (<I>T</I><SUB>f1</SUB> < <I>T</I>*). The spectra just below <I>T</I>* (<I>T</I><SUB>f1</SUB> < <I>T</I> < <I>T</I>*) exhibit a relaxation behavior caused by critical spin fluctuations, indicating the existence of short-range correlations. The stochastic model of ionic spin relaxation was used to account for the shape of the Mössbauer spectra below the freezing temperature. A complex slow dynamics is further supported by ESR data revealing two different absorption modes presumably related to ordered and disordered segments of spin chains. The data imply a spin-cluster ground state for Na<SUB>2</SUB>FeSbO<SUB>5</SUB>.</P><P>A new oxide, sodium−iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized, and its structural and magnetic properties were studied. The system does not undergo a long-range magnetic order in agreement with the fact that it is a one-dimensional magnetic chain system. The mapping analysis based on density functional theory calculations shows a strong one-dimensional, antiferromagnetic intrachain exchange coupling of ∼200 K.</P> [FIG OMISSION]</BR>