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DOE OSTI2020

Materials Data on PuB2C by Materials Project

PuB2C crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Pu4+ sites. In the first Pu4+ site, Pu4+ is bonded to six equivalent C4- atoms to form corner-sharing PuC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Pu–C bond lengths are 2.53 Å. In the second Pu4+ site, Pu4+ is bonded in a 3-coordinate geometry to three equivalent C4- atoms. All Pu–C bond lengths are 2.36 Å. B is bonded in a distorted single-bond geometry to one C4- atom. The B–C bond length is 1.49 Å. C4- is bonded to four Pu4+ and two equivalent B atoms to form a mixture of distorted edge and corner-sharing CPu4B2 octahedra. The corner-sharing octahedra tilt angles range from 0–79°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Cs2Pu(Cl2O)2 by Materials Project

Cs2Pu(OCl2)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Cs1+ is bonded in a 9-coordinate geometry to one O2- and eight equivalent Cl1- atoms. The Cs–O bond length is 3.74 Å. There are a spread of Cs–Cl bond distances ranging from 3.63–3.75 Å. Pu6+ is bonded in a distorted linear geometry to two equivalent O2- and four equivalent Cl1- atoms. Both Pu–O bond lengths are 1.78 Å. All Pu–Cl bond lengths are 2.67 Å. O2- is bonded in a single-bond geometry to one Cs1+ and one Pu6+ atom. Cl1- is bonded in a 1-coordinate geometry to four equivalent Cs1+ and one Pu6+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Pu4ZrC5 by Materials Project

Pu4ZrC5 is Caswellsilverite-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Pu4+ sites. In the first Pu4+ site, Pu4+ is bonded to six C4- atoms to form PuC6 octahedra that share corners with three equivalent PuC6 octahedra, corners with three equivalent ZrC6 octahedra, edges with three equivalent ZrC6 octahedra, and edges with nine PuC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.44 Å) and three longer (2.49 Å) Pu–C bond lengths. In the second Pu4+ site, Pu4+ is bonded to six C4- atoms to form a mixture of edge and corner-sharing PuC6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.46 Å) and three longer (2.48 Å) Pu–C bond lengths. Zr4+ is bonded to six equivalent C4- atoms to form ZrC6 octahedra that share corners with six equivalent PuC6 octahedra, edges with six equivalent PuC6 octahedra, and edges with six equivalent ZrC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Zr–C bond lengths are 2.43 Å. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to six Pu4+ atoms to form a mixture of edge and corner-sharing CPu6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the second C4- site, C4- is bonded to six equivalent Pu4+ atoms to form a mixture of edge and corner-sharing CPu6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third C4- site, C4- is bonded to three equivalent Pu4+ and three equivalent Zr4+ atoms to form a mixture of edge and corner-sharing CPu3Zr3 octahedra. The corner-sharing octahedra tilt angles range from 0–1°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Pu2Si5Pt3 by Materials Project

Pu2Pt3Si5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Pu3+ is bonded in a 1-coordinate geometry to seven Pt+0.67- and ten Si+0.80- atoms. There are a spread of Pu–Pt bond distances ranging from 3.08–3.44 Å. There are a spread of Pu–Si bond distances ranging from 3.00–3.29 Å. There are two inequivalent Pt+0.67- sites. In the first Pt+0.67- site, Pt+0.67- is bonded in a 6-coordinate geometry to four equivalent Pu3+ and six Si+0.80- atoms. There are four shorter (2.50 Å) and two longer (2.57 Å) Pt–Si bond lengths. In the second Pt+0.67- site, Pt+0.67- is bonded in a 5-coordinate geometry to five equivalent Pu3+ and five Si+0.80- atoms. There are a spread of Pt–Si bond distances ranging from 2.38–2.45 Å. There are three inequivalent Si+0.80- sites. In the first Si+0.80- site, Si+0.80- is bonded in a 4-coordinate geometry to four equivalent Pu3+ and four equivalent Pt+0.67- atoms. In the second Si+0.80- site, Si+0.80- is bonded in a 3-coordinate geometry to four equivalent Pu3+, three Pt+0.67-, and two equivalent Si+0.80- atoms. Both Si–Si bond lengths are 2.51 Å. In the third Si+0.80- site, Si+0.80- is bonded in a 9-coordinate geometry to four equivalent Pu3+, three Pt+0.67-, and two equivalent Si+0.80- atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on PuMoBrO5 by Materials Project

PuMoO5Br crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Pu5+ is bonded in a 4-coordinate geometry to four O2- and two equivalent Br1- atoms. There are a spread of Pu–O bond distances ranging from 1.81–2.35 Å. There are one shorter (2.95 Å) and one longer (3.03 Å) Pu–Br bond lengths. Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 1.75–1.83 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Pu5+ and one Mo6+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Pu5+, one Mo6+, and two equivalent Br1- atoms. There are one shorter (3.26 Å) and one longer (3.49 Å) O–Br bond lengths. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Mo6+ and one Br1- atom. The O–Br bond length is 3.03 Å. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Pu5+ and three equivalent Br1- atoms. There are a spread of O–Br bond distances ranging from 3.04–3.59 Å. In the fifth O2- site, O2- is bonded in a linear geometry to one Pu5+ and one Mo6+ atom. Br1- is bonded in a 2-coordinate geometry to two equivalent Pu5+ and six O2- atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on PuB4ClO8 by Materials Project

PuB4O8Cl crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Pu5+ is bonded in a 2-coordinate geometry to two O2- and two equivalent Cl1- atoms. There are one shorter (2.01 Å) and one longer (2.02 Å) Pu–O bond lengths. There are one shorter (2.86 Å) and one longer (2.91 Å) Pu–Cl bond lengths. There are four inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.36 Å) and one longer (1.41 Å) B–O bond length. In the second B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.44–1.49 Å. In the third B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.49 Å. In the fourth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.36–1.41 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Pu5+ and one B3+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two B3+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two B3+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two B3+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Pu5+ and one B3+ atom. Cl1- is bonded in a 2-coordinate geometry to two equivalent Pu5+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on PuTcB2 by Materials Project

PuTcB2 is Magnesium tetraboride-derived structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Pu3+ is bonded in a 3-coordinate geometry to one Tc3- and six equivalent B atoms. The Pu–Tc bond length is 2.85 Å. There are a spread of Pu–B bond distances ranging from 2.65–2.75 Å. Tc3- is bonded in a 7-coordinate geometry to one Pu3+ and six equivalent B atoms. There are a spread of Tc–B bond distances ranging from 2.26–2.31 Å. B is bonded in a 8-coordinate geometry to three equivalent Pu3+, three equivalent Tc3-, and two equivalent B atoms. Both B–B bond lengths are 1.81 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Pu2TeO2 by Materials Project

Pu2O2Te crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pu3+ is bonded in a 4-coordinate geometry to four equivalent Te2- and four equivalent O2- atoms. All Pu–Te bond lengths are 3.44 Å. All Pu–O bond lengths are 2.30 Å. Te2- is bonded in a distorted body-centered cubic geometry to eight equivalent Pu3+ atoms. O2- is bonded to four equivalent Pu3+ atoms to form a mixture of corner and edge-sharing OPu4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Report to NCSP on 2008 DANCE measurements of 233 U($\eta$,$\gamma$)

Uranium-233 plays an important role in the Th-U fuel cycle, with substantial production in the cycle. This cycle has been proposed as an alternative to the U-Pu fuel cycle due to its reduced production of transuranic elements. An accurate measurement of the 233 U($\eta$,$\gamma$) cross section is required by the National Criticality Safety Program (NCSP) to complete the neutron-induced cross section data, where experimental capture cross section data are scarce and were measured decades ago. The most recent capture cross section data available in the literature were measured in 2007 at the n_TOF facility (CERN); in the 60s measurements were performed at Rensselaer Polytechnic Institute (RPI) and at LANL. Finally, as reported by ORNL, a new evaluation with a revised (renormalized) fission cross section is needed on 233 U. The challenge for this measurement lies in the difficulty of measuring the capture cross section data in the competing fission background, as the fission cross section is around one order of magnitude larger than the capture cross section for 233 U. The accuracy of a capture cross section measurement depends on discrimination between $\gamma$’s produced in capture and fission reactions, for which an experimental setup combining capture and fission detectors is needed. For the ($\eta$,$\gamma$) cross section measurement at LANSCE, this discrimination is achieved by combining the Detector for Advanced Neutron Capture Experiments (DANCE), to measure $\gamma$’s from capture reactions, with a Parallel Plate Avalanche Counter (PPAC) to tag the $\gamma$’s produced by fission. This method was successfully used to measure 235 U and 239 Pu capture cross sections. In these measurements, the neutron capture cross section was determined in a large fission background well above 100 keV. As part of the NCSP nuclear data effort, we have looked at past DANCE measurements on 233 U($\eta$,$\gamma$) and evaluated whether existing data is adequate to apply this technique.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2020

INDEN Fissile Actinide Issues [Slides]

This presentation addresses the outlook for the International Nuclear Data Evaluation Network (INDEN), specifically regarding general issues that have been solved, including Thermal Neutron Constants (TNC) and Prompt Fission Neutron Spectra (PFNS). Other topics discussed include outstanding issues in fissile evaluations, comments on the RPI quasi-differential experiment, and reaction rate testing of trial evaluations in fast assemblies. The presentation concludes by discussing how INDEN interactions strongly helped to find deficiencies in existing evaluations and highlighted potential solutions to existing challenges, that updated trial evaluations for U-235, U-233, Pu-239 are available for testing, that further work is expected on U-235, Pu-239, and U-233, and that performance was tested on the ICSBEP and/or SINBAD benchmarks, during which significant improvement was demonstrated. The INDEN scheme of international collaboration on nuclear data evaluation is working well.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2025

Challenges and Perspectives in Lignin‐Derived Polyurethane Foam Synthesis

Abstract Polyurethane foams (PUFs) represent a significant segment of the polyurethane (PU) and cellular plastics industries, owing to their versatile applications and desirable properties. However, the production of PUFs heavily relies on petroleum‐derived chemicals, including polyols and isocyanates, raising critical environmental concerns. Lignin, an abundant aromatic macromolecule, offers a promising alternative for replacing petroleum‐based polyols because of its intrinsic hydroxyl groups. While efforts have been made to produce and apply various lignin‐based polyurethane foams (LPUFs), their commercialization remains limited by challenges such as low product consistency, poor technical performances, and high production costs. This study critically evaluates recent advances in the development of LPUFs, including innovative synthesis methods, functional applications, and emerging research trends. Moreover, potential strategies are discussed, such as lignin fractionation, modification, and co‐solvent assistance, for addressing the challenges. By resolving them, LPUFs could play a pivotal role in transitioning the PU industry to help achieve a circular bioeconomy.

Zhang, Mairui [Carl and Melinda Helwig Department ↗

DOE OSTI2022

f‐ block MOFs: A Pathway to Heterometallic Transuranics

Abstract A novel series of heterometallic f ‐block‐frameworks including the first examples of transuranic heterometallic 238 U/ 239 Pu‐metal–organic frameworks (MOFs) and a novel monometallic 239 Pu‐analog are reported. In combination with theoretical calculations, we probed the kinetics and thermodynamics of heterometallic actinide(An)‐MOF formation and reported the first value of a U‐to‐Th transmetallation rate. We concluded that formation of uranyl species could be a driving force for solid‐state metathesis. Density of states near the Fermi edge, enthalpy of formation, band gap, proton affinity, and thermal/chemical stability were probed as a function of metal ratios. Furthermore, we achieved 97 % of the theoretical maximum capacity for An‐integration. These studies shed light on fundamental aspects of actinide chemistry and also foreshadow avenues for the development of emerging classes of An‐containing materials, including radioisotope thermoelectric generators or metalloradiopharmaceuticals.

Park, Kyoung Chul↗

DOE OSTI2022

f‐ block MOFs: A Pathway to Heterometallic Transuranics

Park, Kyoung Chul↗

DOE OSTI2025

Unique & challenging aspects of plutonium metal standards exchange program for actinide measurements

The Los Alamos National Laboratory exchange program is the only program of its kind for the distribution of plutonium (Pu) standards materials with a range of impurity contents to multiple laboratories for destructive measurements of elemental concentration. This paper discusses statistical methods used to address challenges in Pu metal exchange data by way of two case studies. Challenges include how to evaluate a data set when a large fraction of the values are minimum detection limits (MDLs), and how to determine potential outliers with limited in-formation on the true spread of the data.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Radioisotope dating of nuclear materials using cryogenic decay energy spectrometry

Cryogenic decay energy spectrometry provides high energy resolution and enables absolute decay counting, offering an alternative measurement technique for radiochronometry. A cryogenic decay energy spectrometry experiment was conducted using a magnetic microcalorimeter to determine the age of a plutonium sample. The energy resolution was measured at 0.05% from 5 to 6 MeV. The time since sample purification was determined using the measured concentration ratio of the 241 Am/ 241 Pu radiochronometer. Sample age estimates based on 241 Pu alpha-decay and beta-decay counts, along with 241 Am decay counts, align with the expected sample age within expanded uncertainty (k = 2), supporting the accuracy of cryogenic decay energy spectrometry as a radiochronometric method.

and nuclear chemistry↗

DOE OSTI2020

Preliminary design of control rods in the single-fluid double-zone thorium molten salt reactor (SD-TMSR)

Recent studies on Molten Salt Reactors (MSRs) showed that the excess reactivity at the beginning of the operation is large for many fueling strategies and must be compensated by a reactivity control system. The current work introduces a reliable safety system based on control rods in addition to the online feed system reactivity control in the Single-fluid Double-zone Thorium-based Molten Salt Reactor (SD-TMSR). Three different initial fissile loadings are considered: 233 U, reactor-grade Pu, and transuranic (TRU) elements as a startup fuel. We applied six different absorbing materials to investigate the main operational and safety parameters in the SD-TMSR: natural B 4 C, enriched B 4 C with 90% 10 B, HfB 2 , HfH 1.62 , Eu 2 O 3 , and Gd 2 O 3 . The present work focuses on control rod design, integral and differential control rod worth, shutdown margin, and shadowing effects at steady-state. We employed the SERPENT-2 Monte-Carlo code to calculate the reactivity worth and analyze the performance of the reactivity control system. We showed that 233 U and reactor-grade Pu startup cores maintain adequate shutdown margin with all considered absorbers. Finally, this report proposes a design of control rod clusters that compensate the excess reactivity of the SD-TMSR loaded with different initial fissile material.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2021

Which nuclear data can be validated with LLNL pulsed-sphere experiments?

It is shown here that 14-MeV D+T LLNL pulsed-sphere experiments bring complementary information into the process of validating nuclear data compared to experiments that are traditionally used for this purpose—such as critical assemblies. To be more specific, the 14-MeV D+T LLNL pulsed-sphere neutron-leakage spectra enable to validate scattering and fission nuclear data up to 15 MeV (compared to approximately up to 5 MeV when using criticality experiments) and employ to this end simple compound targets containing only few isotopes. In this work, sensitivity profiles of the spectra to nuclear data are calculated in order to understand in detail which isotopes, observables, and energy ranges of nuclear data contribute significantly to their simulation. These profiles are presented for a few selected spheres containing 16 O, 12 C, 56 Fe, and 239 Pu. It is shown that the neutron-leakage spectra of spheres containing light elements are mostly sensitive to elastic- and inelastic-scattering cross sections on discrete levels and corresponding angular distributions. Spheres of structural materials are sensitive to elastic- and inelastic-scattering cross sections, including scattering on discrete levels and the continuum, and double-differential cross sections. Actinide spheres are also strongly sensitive to the fission observables, in particular to the total-fission neutron spectrum. Thin spheres (in which neutrons experience on average less than one scatter) are mostly sensitive to data near the elastic peak, in the energy range from 12–15 MeV, while thicker ones can be sensitive to data at lower incident-neutron energies due to multiple-scattering effects. This information is brought together with simulations of 71 pulsed-sphere neutron-leakage spectra using the ENDF/B-VII.1 and ENDF/B-VIII.0 nuclear-data libraries. This analysis highlights ENDF/B-VIII.0 data that could be further investigated for potential shortcomings ( 6 Li, 12 C, 16 O, 24-26 Mg, 27 Al, 48 Ti, 56 Fe, and 208 Pb) or are likely reliable ( 1,2 H, 7 Li, 9 Be, 14 N, 235,238 U, and 239 Pu) as indicated by validating with LLNL pulsed-sphere experiments.

14-MeV D+T LLNL pulsed-sphere neutron-leakage spec↗

DOE OSTI2023

Cerium oxide impact on fresh and hardened properties of cementitious materials

Cements used in global nuclear waste treatment, storage, and disposal require thorough testing of fresh and cured properties to demonstrate regulatory compliance. Using actual radioactive wastes is often cost-prohibitive during early scoping tests necessitating the use of non-radiological surrogates. Cerium (Ce) is often used as a surrogate for actinides uranium (U) and plutonium (Pu) in spent nuclear fuel, yet few studies have explored how Ce impacts the properties used to qualify a cement for use. Here, this work compares the fresh and cured properties of three classes of cements – ordinary portland cements, ultra-high performance cement composites, and magnesium phosphate cements – each with and without ceria (CeO 2 ). Due to CeO 2 sorption of water (54 vol%) that effectively decreases the water available to hydrate and form binding cement phases, variations in key cement properties were detected that suggest surrogate CeO 2 –cementitious matrices may not be representative of matrix behaviors when using U and Pu sources.

36 MATERIALS SCIENCE↗