Carter, MeganGasparrini, ClaudiaDouglas, James O.Riddle, Nick...
11页
查看更多>>摘要：The neutron irradiation response of a novel hot isostatically pressed SA508 Grade3 steel was studied, such to deduce any influence this unconventional RPV microstructure has on radiation response. In particular, the role of elevated ferrite fraction was investigated. Neutron irradiation was conducted at 155 +/- 10 degrees C to induce 0.1dpa of damage, this corresponded 2.53 +/- 0.63 GPa hardening for the ferrite and 1.94 +/- 0.57 GPa for the bainite as measured by nanoindentation. Atom probe tomography detected the presence of MnNi-Si type clusters in both microconstituent phases. The ferrite microstructure showed a greater percentage of solute atoms available to form clusters than bainite, but it also contained a lower cluster volume fraction and number density compared to the bainite.(c) 2021 Elsevier B.V. All rights reserved.
Reeve, Jacqueline, ISchuessler, Benjamin J.Frazier, William E.Field, David P....
9页
查看更多>>摘要：Grain boundaries and second phase particles are known to have a significant influence on the recrystallization kinetics of metals undergoing thermomechanical processing. Using ex-situ heating methods and electron backscattered diffraction, we deconvoluted the influence of grain boundaries and second phase particles on the recrystallization kinetics in uranium alloyed with 10 wt% molybdenum (U-10Mo). The U-10Mo alloy is a monolithic nuclear fuel relevant to nuclear non-proliferation effort s. In this study, the sample was homogenized at 1173 K (900 degrees C) for 48 h, hot rolled to 20% reduction, and subsequently annealed at 873 K (600 degrees C) in sequential increments to a total of 1320 min. It was observed that upon deformation, dislocations are accumulated in the vicinity of uranium carbides (UCs) which serve as nucleation sites for randomly oriented grains during annealing. Most nucleation occurred in the first 30 min of annealing and favored the grain boundaries and shear bands near the carbides. A simulation of recrystallization coupling the finite element method (FEM) and the Kinetic Monte Carlo Potts Model (KMCPM) was developed to investigate the grain structure evolution in the polycrystalline U-10Mo fuel. The observed U-10Mo recrystallization and grain growth kinetics with respect to time and temperature was quantitatively reproduced.Published by Elsevier B.V.
查看更多>>摘要：Secure disposal of radioactive wastewater had aroused global concerns for human health and ecological environment. Uranium (U) and Cesium (Cs) were both typical radioactive elements detected in contaminated water bodies. In response to the environmental problem, a spongy-like aerogel adsorbent was firstly prepared for the removal of radioactive U(VI) and Cs(I) and potential application in sea water. MgAlFe layered double hydroxides (LDHs) were prepared by hydrothermal method, and were then gelated by freeze-drying technique to synthesize the calcium alginate aerogels doped with MgAlFe LDHs (CAA@MgAlFe). The prepared CAA@MgAlFe was a kind of porous sponge-like aerogel, on which the LDHs dispersed uniformly. Batch adsorption experiments presented that the adsorption of U(VI) and Cs(I) could reach the equilibrium rapidly in only 4 min and 3 min, respectively. This suggested the reduction of radioactive exposure during the treatment was at a high extent. The adsorption capacities of U(VI) and Cs(I) were as high as 533 and 58 mg/g, respectively. Furthermore, the adsorption isotherms showed that U(VI) and Cs(I) matched well with the Langmuir and Freundlich models, respectively. CAA@MgAlFe could be easily separated and compressed, and its application on sea water was proved to be feasible. The adsorption mechanism of CAA@MgAlFe towards U(VI) included complexation, ion exchange and reduction, while that of Cs(I) was electrostatic attraction.(c) 2021 Published by Elsevier B.V.
Weilert, T. M.Walton, K. L.Loyalka, S. K.Brockman, J. D....
12页
查看更多>>摘要：Silver-110m transport through intact TRISO fuel particles under normal HTGR operating conditions is a well-documented phenomenon. Recent and past literature has shown the significance of palladium attack on SiC potentially facilitating the transport of silver through this otherwise intact layer. Migration of these fission products through TRISO fuel particles will result in their subsequent deposition into, and transport through, further release barriers including structural graphite. A diffusion cell designed to simulate HTGR conditions was constructed and connected to an ICP-MS and used to perform time-release diffusion measurements at standard and off-normal HTGR operating temperatures (1073 K - 1973 K). Silver and palladium release rates were measured in IG-110 graphite loaded individually or together, the latter of which consisted of silver and palladium co-loaded in the graphite samples. Effective diffusivities of silver and palladium were calculated from these release rates. The results of this work, summarized using the Arrhenius equation, are: Ag in IG-110 graphite loaded with Ag: D-Ag ,D- IG-110 = ( 2 . 7 x 10 (-1m2) /(s))exp( -2. 24 x10(5 J)/mol/RT ) Ag in IG-110 graphite loaded with Ag and Pd:D (Ag) ((+ Pd ) , IG-110) = ( 8 . 7 x 10(-3m2) /(s))exp( -1. 78 x10( 5J)/mol/RT ) Pd in IG-110 graphite loaded with Ag and Pd: D-Pd ( +Ag),D- IG -110 = ( 6 . 7 x 10(0)m(2)/(s))exp( -3. 83 x10( 5 J)/mol/RT ) (C)2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Whilst substantial progress has been made in understanding the influence that hydrides have on the me-chanical properties of zirconium alloys, there is currently an urgent need for a transparent, reproducible image analysis workflow for their characterisation. In this study, an open-source software package for the analysis of hydride networks, HAPPy (Hydride Analysis Package in Python), is introduced to calculate the radial hydride fraction (RHF) and mean hydride length, as well as characterising the connectivity of the microstructure both quantitatively and qualitatively. In this study, we used the Hough line transform to calculate the orientation distribution of the hydride segments within a micrograph, and its projection on to the radial direction is used to determine the RHF. The proposed methodology is validated, and its ro-bustness is demonstrated over a wide range of microstructures. The image processing prior to analysis as well as the projection method used has been shown to have a significant influence on the calculated RHF, highlighting the need for standardized image analysis workflows to facilitate accurate comparisons and correlations across different studies in the literature. Finally, this paper introduces a new damage sus-ceptibility parameter termed the branch length fraction, which can be used in conjunction with a path of lowest cost algorithm to visualise the most plausible crack path as well as the connectivity evolution over an entire micrograph. (C)& nbsp;2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Chromium-coated zirconium alloys are one of the promising candidates for accident-tolerant fuel cladding (ATF) tubes for light water reactors (LWRs). In this study, the high temperature oxidation and degradation of two types of Cr coatings (cold spray and physical vapor deposition) with and without pre-damage by scratches were investigated on prototype rod segment samples filled with ZrO2 pellets and tightly sealed with welded end caps. Isothermal tests at 1100 and 1200 degrees C were terminated by quenching with water; transient tests were performed up to 1500-1600 degrees C until complete coating failure. The positive effect of both types of Cr coatings was observed in all tests. Pre-damaged specimens showed only locally increased oxidation of the scratched zone, but no negative effects on the adjacent Cr coating. The behavior of the two types of coatings is compared and the degradation mechanisms are discussed based on hydrogen release data, extensive metallographic post-test examinations, and the current state of global research. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Revealing the corrosion mechanism of materials in supercritical water (SCW) is a key issue for the development of a supercritical water reactor (SCWR). Considering cold work is inevitable in the construction of nuclear reactors and its effect on the corrosion behavior of materials in SCW is still unclear, the corrosion behavior of solution-annealed (as-received) and 30% cold-worked Alloy 800H were studied at 600 degrees C in aerated SCW for 1500 h. The microstructure of the oxide scale was studied by a variety of characterization techniques. The results indicate that cold work increases the corrosion rate of the materials, promotes selective oxidation and internal oxidation, and this was attributed to the high diffusion rate of different ions along "short-circuit paths". The oxide scale composition and structure of the cold worked material, which is subdivided to Fe3O4/NixFe3-xO4/NixFeyCr3-x-yO4/Cr2O3/NiO/ FexCr2-xO4 + pure Ni multi-layer structure, are much more complicated than the as-received material after 1500 h exposure. Combined with the thermo-dynamic equilibrium calculation, the oxidation processes of the as-received and cold-worked materials were analyzed to reveal the effect of cold work on the corrosion behavior of Alloy 800H. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：In this study, free solidification simulation (FSS) and interface fluctuation simulation (FS), which were both based on molecular dynamic (MD) methods, were employed to calculate the solidification kinetic coefficients of gamma metallic uranium. The calculation results of FSS were mu(100 )= 31.94 cm/s/K, mu(110) = 35.61 cm/s/K, and mu(111) = 28.42 cm/s/K; while the results of FS were mu 100 = 39.99 cm/s/K, mu(110) = 33.78 cm/s/K, and mu(111) = 36.80 cm/s/K, indicating that FSS and FS have similar performance. (C) 2021 Elsevier B.V. All rights reserved.
Xiu, PengyuanMassey, Caleb P.Green, T. M. KelsyTaller, Stephen...
15页
查看更多>>摘要：The microstructural responses under 5 MeV Fe 2 + single-ion-beam irradiation of three conditions of additive-manufactured (AM) HT9 steel using a powder-based directed energy deposition (DED) technique with and without postbuild heat treatments were investigated. Besides the observed dislocation loop formation and the absence of cavities at the irradiation condition of 50 dpa at 460 degrees C, Ni/Si/Mn-rich precipitates are found to form in all three conditions of AM-HT9, whereas Cu-rich clusters that arise from Cu uptake from the DED process are only observed in the heat-treated conditions, and not in the as-built (ASB) condition. Coprecipitation of the Cu- and Ni/Si/Mn-rich clusters occur near defect sinks such as line dislocations and grain boundaries in the heat-treated AM-HT9. The variation in microchemical evolution can be directly linked to the starting sink strength of the 3 AM-HT9 conditions, and the ASB condition with higher sink strength suppressed the responses observed in the postbuild heat-treated specimens. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The neutron irradiation of Be, Be-5Ti and Be-7Ti samples in the HFR, Petten, the Netherlands, at temperatures of 710, 800, 940, 1040 K up to damage doses of 23, 31, 36, 38 dpa, respectively, leads to a degradation in the thermal conductivity, depending on the Be-phase content and the radiation-induced porosity in these materials. The Be samples irradiated at the two highest irradiation temperatures of 940 and 1040 K have a maximum drop in the thermal conductivity because these samples have the highest porosity. A lesser decrease in the thermal conductivity of Be-5Ti and Be-7Ti materials occurs for all four irradiation temperatures of 710, 800, 940, 1040 K. The thermal conductivity of Be-5Ti and Be-7Ti depends on the Be-phase content in both initial and irradiated states. The Be-7Ti material contains a minimum volume fraction of the Be-phase, therefore, it has minimum values of the thermal conductivity for both unirradiated (43-50 W/(m center dot K)) and irradiated (30-38 W/(m center dot K)) states. (c) 2021 Elsevier B.V. All rights reserved.
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