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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Nd3Pu by Materials Project

PuNd3 is beta-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Pu is bonded to six equivalent Pu and six equivalent Nd atoms to form PuNd6Pu6 cuboctahedra that share corners with six equivalent PuNd6Pu6 cuboctahedra, corners with six equivalent NdNd12 cuboctahedra, edges with six equivalent PuNd6Pu6 cuboctahedra, edges with eighteen NdNd12 cuboctahedra, faces with six equivalent PuNd6Pu6 cuboctahedra, and faces with twelve equivalent NdNd9Pu3 cuboctahedra. There are four shorter (3.46 Å) and two longer (3.54 Å) Pu–Pu bond lengths. There are two shorter (3.40 Å) and four longer (3.42 Å) Pu–Nd bond lengths. There are two inequivalent Nd sites. In the first Nd site, Nd is bonded to twelve Nd atoms to form NdNd12 cuboctahedra that share corners with six equivalent PuNd6Pu6 cuboctahedra, corners with six equivalent NdNd12 cuboctahedra, edges with six equivalent PuNd6Pu6 cuboctahedra, edges with eighteen NdNd12 cuboctahedra, and faces with eighteen NdNd12 cuboctahedra. There are a spread of Nd–Nd bond distances ranging from 3.46–3.69 Å. In the second Nd site, Nd is bonded to three equivalent Pu and nine Nd atoms to form distorted NdNd9Pu3 cuboctahedra that share corners with eighteen equivalent NdNd9Pu3 cuboctahedra, edges with six equivalent PuNd6Pu6 cuboctahedra, edges with twelve NdNd12 cuboctahedra, faces with six equivalent PuNd6Pu6 cuboctahedra, and faces with fourteen NdNd12 cuboctahedra. There are four shorter (3.46 Å) and two longer (3.54 Å) Nd–Nd bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu3Mg by Materials Project

MgPu3 is Magnesium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mg is bonded to twelve equivalent Pu atoms to form MgPu12 cuboctahedra that share corners with six equivalent MgPu12 cuboctahedra, corners with twelve equivalent PuPu8Mg4 cuboctahedra, edges with eighteen equivalent PuPu8Mg4 cuboctahedra, faces with eight equivalent MgPu12 cuboctahedra, and faces with twelve equivalent PuPu8Mg4 cuboctahedra. There are six shorter (3.31 Å) and six longer (3.36 Å) Mg–Pu bond lengths. Pu is bonded to four equivalent Mg and eight equivalent Pu atoms to form PuPu8Mg4 cuboctahedra that share corners with four equivalent MgPu12 cuboctahedra, corners with fourteen equivalent PuPu8Mg4 cuboctahedra, edges with six equivalent MgPu12 cuboctahedra, edges with twelve equivalent PuPu8Mg4 cuboctahedra, faces with four equivalent MgPu12 cuboctahedra, and faces with sixteen equivalent PuPu8Mg4 cuboctahedra. There are six shorter (3.33 Å) and two longer (3.38 Å) Pu–Pu bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaPu by Materials Project

NaPu is High pressure (38.9 GPa) phase of lithium-derived structured and crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Na is bonded in a 11-coordinate geometry to five equivalent Na and six equivalent Pu atoms. There are a spread of Na–Na bond distances ranging from 3.33–3.49 Å. There are a spread of Na–Pu bond distances ranging from 3.41–3.79 Å. Pu is bonded in a 11-coordinate geometry to six equivalent Na and five equivalent Pu atoms. There are a spread of Pu–Pu bond distances ranging from 3.27–3.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbPu by Materials Project

PuTb crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Pu is bonded to six equivalent Pu and six equivalent Tb atoms to form PuTb6Pu6 cuboctahedra that share corners with eighteen equivalent PuTb6Pu6 cuboctahedra, edges with six equivalent PuTb6Pu6 cuboctahedra, edges with twelve equivalent TbTb6Pu6 cuboctahedra, faces with eight equivalent PuTb6Pu6 cuboctahedra, and faces with twelve equivalent TbTb6Pu6 cuboctahedra. All Pu–Pu bond lengths are 3.55 Å. All Pu–Tb bond lengths are 3.58 Å. Tb is bonded to six equivalent Pu and six equivalent Tb atoms to form TbTb6Pu6 cuboctahedra that share corners with eighteen equivalent TbTb6Pu6 cuboctahedra, edges with six equivalent TbTb6Pu6 cuboctahedra, edges with twelve equivalent PuTb6Pu6 cuboctahedra, faces with eight equivalent TbTb6Pu6 cuboctahedra, and faces with twelve equivalent PuTb6Pu6 cuboctahedra. All Tb–Tb bond lengths are 3.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu3Ta by Materials Project

Pu3Ta is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pu is bonded to eight equivalent Pu and four equivalent Ta atoms to form PuPu8Ta4 cuboctahedra that share corners with twelve equivalent PuPu8Ta4 cuboctahedra, edges with eight equivalent TaPu12 cuboctahedra, edges with sixteen equivalent PuPu8Ta4 cuboctahedra, faces with four equivalent TaPu12 cuboctahedra, and faces with fourteen equivalent PuPu8Ta4 cuboctahedra. All Pu–Pu bond lengths are 2.97 Å. All Pu–Ta bond lengths are 2.97 Å. Ta is bonded to twelve equivalent Pu atoms to form TaPu12 cuboctahedra that share corners with twelve equivalent TaPu12 cuboctahedra, edges with twenty-four equivalent PuPu8Ta4 cuboctahedra, faces with six equivalent TaPu12 cuboctahedra, and faces with twelve equivalent PuPu8Ta4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuN2O11 by Materials Project

(PuO4)2(NO3)4O2 is Cyanogen Chloride-like structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four nitric acid molecules, two water molecules, and two PuO4 clusters. In one of the PuO4 clusters, Pu is bonded in a square co-planar geometry to four equivalent O atoms. There is two shorter (1.80 Å) and two longer (1.81 Å) Pu–O bond length. O is bonded in a single-bond geometry to one Pu atom. In one of the PuO4 clusters, Pu is bonded in a square co-planar geometry to four equivalent O atoms. There is two shorter (1.80 Å) and two longer (1.81 Å) Pu–O bond length. O is bonded in a single-bond geometry to one Pu atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm3Pu by Materials Project

PuSm3 is beta-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Pu is bonded to six equivalent Pu and six equivalent Sm atoms to form PuSm6Pu6 cuboctahedra that share corners with six equivalent PuSm6Pu6 cuboctahedra, corners with six equivalent SmSm12 cuboctahedra, edges with six equivalent PuSm6Pu6 cuboctahedra, edges with eighteen SmSm12 cuboctahedra, faces with six equivalent PuSm6Pu6 cuboctahedra, and faces with twelve equivalent SmSm9Pu3 cuboctahedra. There are four shorter (3.56 Å) and two longer (3.59 Å) Pu–Pu bond lengths. There are two shorter (3.52 Å) and four longer (3.53 Å) Pu–Sm bond lengths. There are two inequivalent Sm sites. In the first Sm site, Sm is bonded to twelve Sm atoms to form SmSm12 cuboctahedra that share corners with six equivalent PuSm6Pu6 cuboctahedra, corners with six equivalent SmSm12 cuboctahedra, edges with six equivalent PuSm6Pu6 cuboctahedra, edges with eighteen SmSm12 cuboctahedra, and faces with eighteen SmSm12 cuboctahedra. There are a spread of Sm–Sm bond distances ranging from 3.56–3.71 Å. In the second Sm site, Sm is bonded to three equivalent Pu and nine Sm atoms to form SmSm9Pu3 cuboctahedra that share corners with eighteen equivalent SmSm9Pu3 cuboctahedra, edges with six equivalent PuSm6Pu6 cuboctahedra, edges with twelve SmSm12 cuboctahedra, faces with six equivalent PuSm6Pu6 cuboctahedra, and faces with fourteen SmSm12 cuboctahedra. There are four shorter (3.56 Å) and two longer (3.59 Å) Sm–Sm bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu3Zr by Materials Project

Pu3Zr is alpha Samarium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Pu is bonded to eight equivalent Pu and four equivalent Zr atoms to form PuPu8Zr4 cuboctahedra that share corners with four equivalent ZrPu12 cuboctahedra, corners with fourteen equivalent PuPu8Zr4 cuboctahedra, edges with six equivalent ZrPu12 cuboctahedra, edges with twelve equivalent PuPu8Zr4 cuboctahedra, faces with four equivalent ZrPu12 cuboctahedra, and faces with sixteen equivalent PuPu8Zr4 cuboctahedra. There are two shorter (3.22 Å) and six longer (3.31 Å) Pu–Pu bond lengths. There are two shorter (3.27 Å) and two longer (3.28 Å) Pu–Zr bond lengths. Zr is bonded to twelve equivalent Pu atoms to form ZrPu12 cuboctahedra that share corners with six equivalent ZrPu12 cuboctahedra, corners with twelve equivalent PuPu8Zr4 cuboctahedra, edges with eighteen equivalent PuPu8Zr4 cuboctahedra, faces with eight equivalent ZrPu12 cuboctahedra, and faces with twelve equivalent PuPu8Zr4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuIn by Materials Project

PuIn crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Pu is bonded to six equivalent Pu and six equivalent In atoms to form a mixture of distorted corner, edge, and face-sharing PuPu6In6 cuboctahedra. There are four shorter (3.31 Å) and two longer (3.47 Å) Pu–Pu bond lengths. There are four shorter (3.37 Å) and two longer (3.38 Å) Pu–In bond lengths. In is bonded in a 12-coordinate geometry to six equivalent Pu and six equivalent In atoms. There are four shorter (3.31 Å) and two longer (3.47 Å) In–In bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SmPu by Materials Project

PuSm crystallizes in the monoclinic Pm space group. The structure is three-dimensional. Pu is bonded to six equivalent Pu and six equivalent Sm atoms to form PuSm6Pu6 cuboctahedra that share corners with eighteen equivalent PuSm6Pu6 cuboctahedra, edges with six equivalent PuSm6Pu6 cuboctahedra, edges with twelve equivalent SmSm6Pu6 cuboctahedra, faces with eight equivalent PuSm6Pu6 cuboctahedra, and faces with twelve equivalent SmSm6Pu6 cuboctahedra. There are a spread of Pu–Pu bond distances ranging from 3.57–3.63 Å. There are four shorter (3.61 Å) and two longer (3.63 Å) Pu–Sm bond lengths. Sm is bonded to six equivalent Pu and six equivalent Sm atoms to form SmSm6Pu6 cuboctahedra that share corners with eighteen equivalent SmSm6Pu6 cuboctahedra, edges with six equivalent SmSm6Pu6 cuboctahedra, edges with twelve equivalent PuSm6Pu6 cuboctahedra, faces with eight equivalent SmSm6Pu6 cuboctahedra, and faces with twelve equivalent PuSm6Pu6 cuboctahedra. There are a spread of Sm–Sm bond distances ranging from 3.57–3.63 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Radiolytic degradation of 240 Plutonium and 242 Plutonium oxalates

Raman, FTIR, and diffuse reflectance spectroscopy were used to study the auto-radiolytic degradation of 240 Pu and 242 Pu oxalates. The significant differences in the lifetimes of 240 Pu and 242 Pu enabled the differentiation between environmental and radiolytic mechanisms. 240 Pu oxalates were observed to decompose to PuOCO 3 at intermediate times (~ 20 weeks) followed by partial conversion to PuO 2 at times greater than one year. Atmospheric oxidation was shown to be the primary decomposition mechanism for 242 Pu(IV) oxalate, and the alpha radiolysis of aquo and oxalate ligands serves as a secondary decomposition mechanism. In conclusion, this study offers a fresh perspective on radiolytic aging, which is crucial for long-term storage applications.

Analytical Techniques in Art Conservation↗
DOE OSTI2025

Smaller and faster: a review of conventional and nanocalorimetry techniques for determining thermophysical properties of nuclear materials

Thermal analysis of nuclear materials is critical for the advancement of nuclear technology. The heat effects associated with heat capacity, phase transformation, and radiation damage can be measured with conventional calorimeters. However, conventional calorimetric techniques are often restricted in terms of heating rate and sample mass, especially when studying the limited amounts of materials subject to extreme conditions. In this review, we summarize conventional calorimetric studies of critical thermophysical and thermochemical properties of pure actinide metals (U, Np, Am, Pu), fast reactor metallic fuel alloy systems (U–Zr, U–Pu–Zr, Pu–U, Pu–Zr), and actinide oxides that are primary constituents or transmutation products in light water reactor fuel rods (U–O, Np–O, Am–O, Pu–O, Pu–U–O). Adiabatic and drop calorimetry have been the primary techniques used for these studies, however the development of fast scanning calorimetry using micro-electro-mechanical-based systems allows determination of thermodynamic properties from smaller sample masses. We report recent investigations that leverage the fast heating rates of nanocalorimetry by itself or combined with other characterization techniques. Furthermore, we then discuss opportunities for nanocalorimetry to provide solutions to some of the technical challenges inherent in thermal analysis of nuclear materials, namely a reduction in sample activity, emulating heating transients, investigation of phase evolution in irradiated samples, and characterization of radiation damage evolution. Nanocalorimetry has the potential to significantly advance the understanding of thermophysical properties in nuclear materials and thus accelerate the development of nuclear technology.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Corrosion-resistant polyurethane coatings from structure-homogenized biorefinery lignin through fractionation and oxypropylation

Using lignin for polyurethane (PU) synthesis is challenging because of its heterogeneous structure, i.e., broad molecule weight (MW) distribution and diverse hydroxyl (OH) functionality. This complexity influences the crosslinking reaction between lignin and isocyanate and affects the quality of PU products. Here, we propose a two-step strategy for lignin structure homogenization by lowering its MW and uniforming OH functionality (step 2). Step 1 involves a bioethanol fractionation process, yielding fractionated lignin with one order lower MW than the raw lignin while exhibiting better processability for the subsequent process. Step 2 is performed by an oxyalkylation process using fractionated lignin that converts phenolic and carboxylic OHs to aliphatic OHs. As a result, we obtained structure-homogenized lignin with good compatibility and crosslinking with hexamethylene diisocyanate for PU coating synthesis. Moreover, PU coatings prepared from structure-homogenized lignin display a defect-free microscopic structure and show better corrosion resistance than coatings fabricated from its raw lignin alternative. Overall, the structure homogenization process is a beneficial way of using lignin as biopolyol in PU synthesis toward the application-oriented design of corrosion-resistant lignin-based PU coatings.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Probing thermodynamics of radiogenic helium and defects in $δ$-plutonium alloys and interactions with adsorbed environmental gases

Differential scanning calorimetry coupled with simultaneous evolved gas analysis (DSC-EGA) on aged δ-Pu samples shows that most radiogenic helium remains trapped within the Pu matrix at temperatures very close to, or slightly above, the melting temperature. Our results indicate that helium release from 50-year-old δ-Pu occurs as a burst just below the melting temperature (>0.994 T m ), with subsequent pressure oscillations as temperature increases. Subordinate quantities of H 2 were also released along with helium. Here, the helium emission tails off and ceases above ~720 – 750°C. In a δ-Pu alloy aged 6 years, the initial helium burst occurs slightly above melting (~1.015 – 1.042 T m ), with a discrete, larger helium spike occurring between 670 and 686°C. The proximity of helium release to the liquidus transition presented challenges in the deconvolution of overlapping process enthalpies, the liquidus endotherm, and the exotherm resulting from bubble collapse, annealing and gas expulsion. Helium’s strong affinity for vacancy binding in a 2He-vac configuration is predicted by Density Functional Theory (DFT) modeling. The measured stored energy associated with the He release events in a 50-year-old δ alloy is on the order of ~ 10–11 J/g, which is significantly higher than stored energies measured in the sub-solidus regimes (~2 J/g) that are related to the solid-state annealing of processing- and radiation-induced defects. This implies that aged δ Pu alloys have a remarkable resilience to accommodate the lattice strain produced by the internal pressure of the helium bubbles and provides further insight into the thermodynamic behavior of aged δ Pu.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Insights into the thermal decomposition of plutonium(IV) oxalate – a DFT study of the intermediate structures

The thermal decomposition of plutonium oxalate to oxide is one of the most studied reactions in actinide chemistry but the intermediates have been the subject of debate for decades. Recent experimental data suggest that the decomposition of Pu(IV) oxalate in air undergoes dehydration first, then reduction to Pu(III) oxalate. The precise structural modifications that take place are unknown as experiments have not been able to fully characterize the intermediates at the microscopic level. To rectify this, we employed solid state density functional theory calculations at the PBE-D3 level with a Hubbard U correction to model the structures and energetics of potential dehydrated Pu(IV) and Pu(III) oxalate intermediate compounds. Based on the theoretical study presented here, the anhydrous analogues of the known hydrated Pu(IV) and Pu(III) oxalates are the preferred crystal structures formed through an overall exothermic reaction process. However, decomposition could proceed through the formation of a higher energy, more complicated 3D lattice structure with frustrated oxalate binding. It is expected that the intermediates presented here could be identified using spectroscopic techniques to enable further insight into the reaction mechanism.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Ab initio modeling and thermodynamics of hydrated plutonium oxalates

An ab initio study on the plutonium oxalate hydrates: Pu 2 (C 2 O 4 ) 3 ·10H 2 O and Pu(C 2 O 4 ) 2 ·6H 2 O, using PBE exchange-correlation with D3 dispersion correction and Hubbard correction for the plutonium atoms, was performed and compared to experimental vibrational spectral and thermodynamic property values. Here we demonstrated that this technique can accurately predict the experimental infrared spectra Pu(III) oxalate hydrate, as well as the Raman peak of PuO 2 (used to calculate the thermodynamic properties of the oxalates). For Pu(IV) oxalate hydrate we found that our predicted structure agreed qualitatively with PXRD measurements, the only available experimental determination of the structure. Using this method at standard temperature and pressure, we predicted standard enthalpies of formation of -6,755 kJ mol -1 and -3,923 kJ mol -1 and standard Gibbs free energy of formation of -5,899 kJ mol -1 and -3,386 kJ mol -1 for Pu 2 (C 2 O 4 ) 3 ·10H 2 O and Pu(C 2 O 4 ) 2 ·6H 2 O, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Assessment of alternative radionuclides for use in a radioisotope thermoelectric generator

238 Pu is the current fuel source for MMRTGs. This is due to favorable properties, such as high decay heat and low gamma emissions. 238 Pu supplies are dwindling rapidly, necessitating the review of potential replacement isotopes for deep space missions. This work considers nine potential replacements, Ac-227, Am-241, Cf-252, Cm-244, Cs-137, Po-210, Sr-90, Th-228, and Th-170. We have assessed performance of alternatives to 238 Pu by modeling the specific decay-heat and gamma spectra of several potential radioisotopes in SCALE-ORIGEN, and comparing these with 238 Pu. An analysis of heat output, heat stability, safety, availability and required mass, baselined against 238 Pu demonstrates that of those radioisotopes studied, 241 Am has properties that make it most conducive for 238 Pu replacement.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

A multi-collector ICP-MS method for quantification of plutonium, uranium, and americium in hair and nails of occupationally or medically exposed individuals

The 239 Pu, 238 U, and 241 Am concentrations and 239 Pu/ 240 Pu, 235 U/ 238 U, and 236 U/ 238 U atom ratios were measured in the hair and nail samples from individuals who donated their bodies to the United States Transuranium and Uranium Registries. Further, the concentration of 239 Pu ranged from 0.22–15.8 ng/kg. The 240 Pu/ 239 Pu isotopic ratios ranged from 0.026 to 0.127 which is consistent with weapons-grade plutonium. Concentration of uranium fell between 1.84 µg/kg and 29.5 µg/kg and 235 U/ 238 U ratios ranged from 4.8×10 -3 to 7.6×10 -3 . Elevated 236 U/ 238 U atom ratios were measured in two cases and ranged from 5.0×10 -6 – 2.4×10 -5 indicating exposure to spent or reprocessed uranium material. The concentration of 241 Am was measured in four hair samples and ranged from 0.02–0.21 ng/kg.

61 RADIATION PROTECTION AND DOSIMETRY↗