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At least 649 records · Page 36

Materials Data on HoSnGe by Materials Project

HoSnGe is Zirconium Disilicide-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ho is bonded in a 10-coordinate geometry to four equivalent Sn and six equivalent Ge atoms. There are two shorter (3.24 Å) and two longer (3.33 Å) Ho–Sn bond lengths. There are four shorter (3.02 Å) and two longer (3.22 Å) Ho–Ge bond lengths. Sn is bonded in a 8-coordinate geometry to four equivalent Ho and four equivalent Sn atoms. All Sn–Sn bond lengths are 2.96 Å. Ge is bonded in a 8-coordinate geometry to six equivalent Ho and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.71 Å.

36 MATERIALS SCIENCE↗

Materials Data on MgSi2 by Materials Project

MgSi2 is Zirconium Disilicide-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 8-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.77–3.04 Å. In the second Mg site, Mg is bonded in a 8-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.77–3.04 Å. In the third Mg site, Mg is bonded in a 8-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.78–3.05 Å. In the fourth Mg site, Mg is bonded in a 8-coordinate geometry to eight Si atoms. There are a spread of Mg–Si bond distances ranging from 2.78–3.04 Å. There are eight inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.49–2.64 Å. In the second Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.48–2.63 Å. In the third Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.48–2.63 Å. In the fourth Si site, Si is bonded in a 10-coordinate geometry to four Mg and six Si atoms. There are a spread of Si–Si bond distances ranging from 2.62–2.71 Å. In the fifth Si site, Si is bonded in a 10-coordinate geometry to four Mg and six Si atoms. There are one shorter (2.68 Å) and one longer (2.70 Å) Si–Si bond lengths. In the sixth Si site, Si is bonded in a 10-coordinate geometry to four Mg and six Si atoms. Both Si–Si bond lengths are 2.49 Å. In the seventh Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. In the eighth Si site, Si is bonded in a 10-coordinate geometry to four Mg and six Si atoms.

36 MATERIALS SCIENCE↗

Materials Data on GdSn2 by Materials Project

GdSn2 is Zirconium Disilicide structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Gd is bonded in a 10-coordinate geometry to ten Sn atoms. There are a spread of Gd–Sn bond distances ranging from 3.19–3.48 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Gd and four equivalent Sn atoms. All Sn–Sn bond lengths are 3.14 Å. In the second Sn site, Sn is bonded in a 4-coordinate geometry to six equivalent Gd and two equivalent Sn atoms. Both Sn–Sn bond lengths are 3.04 Å.

36 MATERIALS SCIENCE↗

Materials Data on Ti4AlGe7 by Materials Project

Ti4AlGe7 is Zirconium Disilicide-derived structured and crystallizes in the tetragonal I-4m2 space group. The structure is three-dimensional. there are two inequivalent Ti sites. In the first Ti site, Ti is bonded in a 10-coordinate geometry to two equivalent Al and eight Ge atoms. Both Ti–Al bond lengths are 2.82 Å. There are a spread of Ti–Ge bond distances ranging from 2.65–2.95 Å. In the second Ti site, Ti is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Ti–Ge bond distances ranging from 2.68–3.06 Å. Al is bonded in a distorted square co-planar geometry to four equivalent Ti and four equivalent Ge atoms. All Al–Ge bond lengths are 2.62 Å. There are five inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to six Ti and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.61 Å. In the second Ge site, Ge is bonded in a 4-coordinate geometry to six Ti and two equivalent Ge atoms. In the third Ge site, Ge is bonded in a 8-coordinate geometry to four equivalent Ti and four equivalent Ge atoms. All Ge–Ge bond lengths are 2.62 Å. In the fourth Ge site, Ge is bonded in a 8-coordinate geometry to four equivalent Ti and four equivalent Al atoms. In the fifth Ge site, Ge is bonded in a 8-coordinate geometry to four equivalent Ti and four equivalent Ge atoms.

36 MATERIALS SCIENCE↗

Materials Data on MgAu2 by Materials Project

Au2Mg is Zirconium Disilicide structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Mg2+ is bonded in a distorted q6 geometry to ten Au1- atoms. There are a spread of Mg–Au bond distances ranging from 2.87–2.94 Å. There are two inequivalent Au1- sites. In the first Au1- site, Au1- is bonded in a 4-coordinate geometry to four equivalent Mg2+ atoms. In the second Au1- site, Au1- is bonded in a 6-coordinate geometry to six equivalent Mg2+ atoms.

36 MATERIALS SCIENCE↗

Materials Data on CaBi2 by Materials Project

Bi2Ca1 is Zirconium Disilicide structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ca is bonded in a 10-coordinate geometry to ten Bi atoms. There are a spread of Ca–Bi bond distances ranging from 3.38–3.71 Å. There are two inequivalent Bi sites. In the first Bi site, Bi is bonded in a 4-coordinate geometry to six equivalent Ca and two equivalent Bi atoms. Both Bi–Bi bond lengths are 3.22 Å. In the second Bi site, Bi is bonded in a 8-coordinate geometry to four equivalent Ca and four equivalent Bi atoms. All Bi–Bi bond lengths are 3.34 Å.

36 MATERIALS SCIENCE↗

Materials Data on Hf3AlGe5 by Materials Project

Hf3AlGe5 is Zirconium Disilicide-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are six inequivalent Hf sites. In the first Hf site, Hf is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Hf–Ge bond distances ranging from 2.78–3.20 Å. In the second Hf site, Hf is bonded in a 10-coordinate geometry to two equivalent Al and eight Ge atoms. Both Hf–Al bond lengths are 2.92 Å. There are a spread of Hf–Ge bond distances ranging from 2.75–3.12 Å. In the third Hf site, Hf is bonded in a 10-coordinate geometry to two equivalent Al and eight Ge atoms. Both Hf–Al bond lengths are 2.93 Å. There are a spread of Hf–Ge bond distances ranging from 2.74–3.06 Å. In the fourth Hf site, Hf is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Hf–Ge bond distances ranging from 2.78–3.20 Å. In the fifth Hf site, Hf is bonded in a 10-coordinate geometry to two equivalent Al and eight Ge atoms. Both Hf–Al bond lengths are 2.95 Å. There are a spread of Hf–Ge bond distances ranging from 2.74–3.05 Å. In the sixth Hf site, Hf is bonded in a 10-coordinate geometry to two equivalent Al and eight Ge atoms. Both Hf–Al bond lengths are 2.94 Å. There are a spread of Hf–Ge bond distances ranging from 2.75–3.11 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 8-coordinate geometry to four Hf and four equivalent Ge atoms. All Al–Ge bond lengths are 2.69 Å. In the second Al site, Al is bonded in a 8-coordinate geometry to four Hf and four equivalent Ge atoms. All Al–Ge bond lengths are 2.69 Å. There are ten inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four Hf and four equivalent Ge atoms. All Ge–Ge bond lengths are 2.69 Å. In the second Ge site, Ge is bonded to four Hf and four equivalent Al atoms to form a mixture of distorted corner and face-sharing GeHf4Al4 hexagonal bipyramids. In the third Ge site, Ge is bonded to four Hf and four equivalent Al atoms to form a mixture of distorted corner and face-sharing GeHf4Al4 hexagonal bipyramids. In the fourth Ge site, Ge is bonded in a 8-coordinate geometry to four Hf and four equivalent Ge atoms. In the fifth Ge site, Ge is bonded in a 4-coordinate geometry to six Hf and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.67 Å. In the sixth Ge site, Ge is bonded in a 4-coordinate geometry to six Hf and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.67 Å. In the seventh Ge site, Ge is bonded in a 4-coordinate geometry to six Hf and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.70 Å. In the eighth Ge site, Ge is bonded in a 4-coordinate geometry to six Hf and two equivalent Ge atoms. In the ninth Ge site, Ge is bonded in a 4-coordinate geometry to six Hf and two equivalent Ge atoms. In the tenth Ge site, Ge is bonded in a 4-coordinate geometry to six Hf and two equivalent Ge atoms.

36 MATERIALS SCIENCE↗

Materials Data on TiSi2 by Materials Project

TiSi2 is Zirconium Disilicide structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ti is bonded in a 10-coordinate geometry to ten Si atoms. There are a spread of Ti–Si bond distances ranging from 2.59–2.82 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to six equivalent Ti and two equivalent Si atoms. Both Si–Si bond lengths are 2.41 Å. In the second Si site, Si is bonded in a 8-coordinate geometry to four equivalent Ti and four equivalent Si atoms. All Si–Si bond lengths are 2.52 Å.

36 MATERIALS SCIENCE↗

Materials Data on MgSi2 by Materials Project

MgSi2 is Zirconium Disilicide structured and crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Mg and ten Si atoms. Both Mg–Mg bond lengths are 3.03 Å. There are a spread of Mg–Si bond distances ranging from 2.76–3.04 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Mg and ten Si atoms. There are a spread of Mg–Si bond distances ranging from 2.77–3.04 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 10-coordinate geometry to six Mg and four Si atoms. There are two shorter (2.56 Å) and two longer (2.80 Å) Si–Si bond lengths. In the second Si site, Si is bonded in a 4-coordinate geometry to four Mg and two equivalent Si atoms. In the third Si site, Si is bonded in a 4-coordinate geometry to four Mg and two equivalent Si atoms. Both Si–Si bond lengths are 2.79 Å. In the fourth Si site, Si is bonded in a 10-coordinate geometry to six Mg and four Si atoms. Both Si–Si bond lengths are 2.56 Å.

36 MATERIALS SCIENCE↗

Materials Data on HfScGe4 by Materials Project

ScHfGe4 is Zirconium Disilicide-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Sc is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Sc–Ge bond distances ranging from 2.79–3.12 Å. Hf is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Hf–Ge bond distances ranging from 2.79–3.13 Å. There are four inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Sc, two equivalent Hf, and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.61 Å. In the second Ge site, Ge is bonded in a 4-coordinate geometry to two equivalent Sc, four equivalent Hf, and two equivalent Ge atoms. In the third Ge site, Ge is bonded in a 8-coordinate geometry to two equivalent Sc, two equivalent Hf, and four equivalent Ge atoms. All Ge–Ge bond lengths are 2.71 Å. In the fourth Ge site, Ge is bonded in a 8-coordinate geometry to two equivalent Sc, two equivalent Hf, and four equivalent Ge atoms.

36 MATERIALS SCIENCE↗

Materials Data on TmSn2 by Materials Project

TmSn2 is Zirconium Disilicide structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tm is bonded in a 10-coordinate geometry to ten Sn atoms. There are a spread of Tm–Sn bond distances ranging from 3.14–3.43 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 4-coordinate geometry to six equivalent Tm and two equivalent Sn atoms. Both Sn–Sn bond lengths are 3.01 Å. In the second Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Tm and four equivalent Sn atoms. All Sn–Sn bond lengths are 3.09 Å.

36 MATERIALS SCIENCE↗

Inferring nuclear structure from heavy isobar collisions using Trajectum

Nuclei with equal number of baryons but varying proton number (isobars) have many commonalities, but differ in both electric charge and nuclear structure. Relativistic collisions of such isobars provide unique opportunities to study the variation of the magnetic field, provided the nuclear structure is well understood. In this work we simulate collisions using several state-of-the-art parametrizations of the ^{96}_{40} 40 96 Zr and ^{96}_{44} 44 96 Ru isobars and show that a comparison with the exciting STAR measurement [arXiv:2109.00131] of ultrarelativistic collisions can uniquely identify the structure of both isobars. This not only provides an urgently needed understanding of the structure of the Zirconium and Ruthenium isobars, but also paves the way for more detailed studies of nuclear structure using relativistic heavy ion collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

SCALE Lattice Physics Code Assessments of Accident Tolerant Fuel

This report highlights accident-tolerant fuel (ATF) code assessment activities performed under Project NRCHQ- 60-17-T-0017, Lattice Physics Enhancements and Assessment. ATF covers a broad range of advanced fuel and clad designs for light water reactors (LWRs) to enhance performance under several accident conditions. Several ATF concepts are anticipated to be deployed as lead test rods (LTRs) or lead test assemblies (LTAs) within the next five years. The purpose of this work is to assess the predictive capabilities of NRC neutronics codes that underpin various licensing calculations. ATF designs use different fuel and clad materials compared to standard UO 2 fuel and zirconium-alloy claddings (hereafter UO 2 -Zry). These new materials and geometrical designs need to be assessed to quantify the impact of nuclear data uncertainties on quantities of interest (QOIs) in licensing calculations and the impact of modeling approximations which may be valid for UO 2 -Zry but not for ATF. This report outlines a systematic approach for ATF neutronics code assessment which includes sensitivity and uncertainty (S/U) analysis of nuclear data, identification of experimental benchmark and gaps for code validation, investigation of modeling approximations, and code-to-code comparisons of calculated QOIs against high-fidelity reference continuous energy (CE) Monte Carlo (MC) calculations. This report focuses on the assessment of the SCALE/Polaris lattice physics code for reactor safety analysis. Polaris lattice physics calculations generate few group (FG) cross sections for PARCS full-core calculations. (Full-core analysis, spent fuel analysis, and severe accident analysis will be performed in future work.) The selected ATF concepts for this report include Cr 2 O 3 and Al 2 O 3 -Cr 2 O 3 -doped UO 2 fuel, U 3 Si 2 fuel, FeCrAl cladding, SiC cladding, and Cr-coated cladding.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Evaluation of Hydrogen Generation in High Burnup Demonstration Dry Storage Cask

This report provides a best-estimate evaluation of residual water content (post-dry out) in the High Burnup (HBU) LWR Spent Fuel Demonstration project TN-32 cask, and evaluates the radiolysis of the residual free water, and the physisorbed and chemisorbed waters on the surfaces of the fuel and cask internal contents. The evaluation of radiolytic breakdown of those waters with gamma radiation causing the generation of hydrogen gas (H 2 ) is made using available literature data and models. This evaluation is part of the overall materials performance evaluation of the SNF-in-canister system, and is part of the technical bases for their continued safe dry storage. The TN-32 cask contents included 32 HBU LWR spent fuel assemblies each with 264 fuel rods clad in zirconium alloys, aluminum neutron absorber components, and aluminum and stainless steel structural components. The residual free and surface (physisorbed/chemisorbed) waters are ascribed to water vapor in the free volume and to components’ surfaces, respectively. The total potential radiolytic hydrogen inventory from the water vapor and from waters ascribed to surfaces has been calculated assuming all the water produced molecular H 2 . The residual water that is chemically incorporated into the bulk of a hydrated oxide, i.e., chemisorbed water, and its total potential hydrogen inventory has been calculated. These calculations are at the physical limit of material available and are used for a bounding assessment purpose only.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

MPA Materials Matter Summer 2020 [Newsletter]

The summer issue of the Materials Physics and Applications division (MPA) newsletter features the following short articles: recognition for Rod Borup, From Wolfgang's Desk (Wolfgang Runde), From Adam's Desk (Adam Rondinone), ''Frustrating harmful dendite formation in potassium ion batteries''; ''From a Mott insulator to an ideal two-dimensional metal''; ''First ever actinide-zirconium framework synthesized''; and finishing with the usual service celebrations and HeadsUp sections.

36 MATERIALS SCIENCE↗

Best Practices for Shielding Analyses of Activated Metals and Spent Resins from Reactor Operation

This report investigated best practices for performing shielding evaluations of Type B waste packages, as defined in 10 CFR Part 71 regulations on packaging and transportation of radioactive material, or packages for which the contents are not defined before loading and may include a broad range of nuclides, geometries, and non-fuel materials. The following non-fuel waste streams were analyzed: Activated metals from decommissioned commercial power reactors, including Type 304 stainless steel, reactor vessel steel, and Inconel, Control blades from boiling water reactors, Neutron-activated corrosion products on surfaces of activated metals, and Spent resins from power plant operations. Measured elemental compositions, including major constituents and impurities, for steel and Inconel samples from commercial power reactors were used in activation calculations to determine radionuclide inventories in activated metals. For a simplified cask model, 60 Co contribution to the total external package dose rate at 30 days after shutdown varied from approximately 60% to 95%, depending on the activated metal, initial cobalt impurity concentration in the metal, and the thickness of the overpack gamma shield. Its maximum contribution to the total external package dose rate of approximately 100% was reached within the time interval of 2 to 5 years after shutdown and was maintained for up to 45 to 60 years after shutdown, depending on material, initial cobalt impurity concentration, and shield thickness. Thereafter, the 60 Co contribution to external package dose rate decreased with increasing decay time. Cobalt-60 is primarily produced by neutron reactions with the cobalt impurity in steel and Inconel. Other important radionuclides in activated metals contributing to package external dose rate are radionuclides with relatively short decay times, including 51 Cr, 59 Fe, 58 Co, and 54 Mn. These radionuclides may be represented as an equivalent 60 Co activity/source because 60 Co gamma ray emissions are bounding in terms of source strength and energy to other important radionuclides identified in the analyzed activated metals. Approaches for modeling the neutron-activated corrosion products that may be attached to activated reactor components were analyzed in this report. It was demonstrated that a surface source is more conservative than a uniform volumetric source for the treatment of neutron-activated corrosion products with respect to external package dose rates. An analysis of the maximum radionuclide loadings reported on spent resins identified the radionuclides 137 Cs, 60 Co, 134 Cs, 65 Zn, and 58 Co as the primary contributors to external package dose rate. For a resin cooled for 3.08 years, the external package dose rate was entirely produced by the reported 137 Cs and 60 Co inventory. The neutron sources from actinides found on spent resins or activated metals produced negligible dose rates and may be ignored in dose rate analyses. Effects of idealized waste material, source geometry, and spatial material/source distributions on external package dose rates were determined based on dose rate results for a simplified cask model under normal conditions of transport. Type 304 stainless steel, zirconium, and aluminum with adjusted mass densities based on a maximum content weight were analyzed for material modeling effects on external package dose rate. These materials produced identical external package dose rates within the statistical uncertainties of the dose rate estimates. Among four different source geometry configurations with homogeneous material of different mass densities, uniform volumetric source distribution, and the same source strength, the geometry configuration with lowest mass density (i.e., minimum self-shielding effect among the four cases) was most conservative. Spatial source distributions that better represent localized peak 60 Co activity values were more conservative than a uniform volumetric source distribution, assuming the same weight and total source strength per package. The increase in external dose rate caused by localized source peaks can be as much as the ratio between source peak activity density to average activity density, depending on the location of the activated metal with peak activity density. Therefore, the shielding analysis may be simplified if localized peak activities and the average activity per package can be measured/determined and documented at the time of cask loading. For simplicity, external package dose rates may be determined based on average source activity and a uniform volumetric source distribution. The dose rate results from that calculation model multiplied by the ratio of peak activity density to average activity density will produce maximum dose rate values for conservative estimates.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

IER-519 CED-2: Final Design for Thermal/Epithermal eXperiments (TEX) with Absorbers to Provide Validation Benchmarks for Hanford Tank Farms

The Hanford tank farms contain 56 million gallons of waste across 177 tanks. The primary criticality safety concern for the waste is the plutonium inventory in waste solids – approximately 670 kg in total. Criticality safety analysis credits the absorption and dilution properties of the large quantities of other elements (aluminum, chromium, iron, manganese, nickel, silicon, sodium, and zirconium) present in the waste. Of these, iron and manganese are by far the most significant neutron absorbers, particularly for the waste compositions of highest criticality safety concern. The criticality safety analyses at the Hanford Waste Treatment and Vitrification Plant (WTP) and the Savannah River tank farms also credit iron and manganese as the primary neutron absorbers to demonstrate subcriticality.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Test Plan for Investigation of Hydrogen Generation in SNF Canisters

This report presents a test plan to investigate radiolytic hydrogen generation in spent nuclear fuel (SNF) canisters containing Zr-based cladding materials. The initial primary contributor to the generation of radiolytic hydrogen is estimated to be the residual physisorbed water on the ZrO 2 film, post-dry out. Over the longer term the primary hydrogen source is associated with the aluminum hydroxides and water vapor. The proposed testing to be conducted in FY22 would consist of lab-scale testing on non-radioactive surrogates of oxidized ZIRLO tubing and unalloyed zirconium using a miniature steel canister (“mini-canister") designed to allow intermittent, in-situ sampling of the canister gas during irradiation. The mini-canister approach for irradiation with in-situ monitoring system was used in a recent and on-going study [McNamara and Verst, 2020a & 2020b; Verst et al., 2021] to measure radiolytic hydrogen generation from aluminum SNF cladding surrogate materials. This proposed testing will form part of the overall materials performance evaluation of the commercial SNF-in-canister system and is part of the technical bases for their continued safe dry storage

08 HYDROGEN↗