Ab Initio Evaluation of Plutonium Dioxide $S(α,β)$ and Thermal Neutron Cross Sections

Conference · Sun Nov 12 00:00:00 EST 2023

OSTI ID:1994523

Crozier, J. P. W. ^[1]; Hawari, A. I. ^[1]

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1. North Carolina State University, Raleigh, NC (United States). Department of Nuclear Engineering

Plutonium Dioxide (PuO₂) is an advanced fuel-cycle nuclear fuel material for thermal and fast reactors, with a melting point at 3261.8 K and thermal conductivity above 3 Wm^-1K^-1 for temperatures below 1500 K. Plutonium from spent UO₂ is reprocessed to form chemically stable mixed oxide (MOX) fuel. In contrast to metallic fuels, the low PuO₂ conductivity results in high thermal gradients between fuel center and surface, resulting in structural annealing and efficient fission product migration over burnup. Crystal binding affects the doppler broadening of epithermal resonances for nuclear fuels and scattering behavior of thermal neutrons. Currently, there is no ENDF/B Thermal Scattering Law, i.e., $S(α,β)$, evaluation for PuO₂, only free atom cross sections for Plutonium and Oxygen, respectively, which neglect lattice contributions to total cross section. Herein, ab initio lattice dynamics (AILD) techniques are employed to calculate the phonon density of states (DOS) using spin-orbit-coupling density functional theory (DFT) to predict the PuO2 paramagnetic ground-state structure. These results highlight the evaluation of $S(α,β)$ for Plutonium and Oxygen, respectively in PuO₂ and consequential generation of thermal neutron scattering cross sections for high fidelity criticality safety analysis and reactor calculations.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); North Carolina State University, Raleigh, NC (United States). Department of Nuclear Engineering
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC52-07NA27344
• OSTI ID: 1994523
• Resource Relation: Conference: 2023 ANS Winter Meeting and Technology Expo, Washington, DC (United States), 12-15 Nov 2023; Related Information: https://www.ans.org/meetings/wm2023/
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Nuclear Criticality Safety Program (NCSP)
Plutonium Dioxide (PuO2)
Nuclear Fuels
Scattering Behavior
Density Functional Theory (DFT)
Phonon Density of States (DOS)
Ab Initio Lattice Dynamics (AILD)
Evaluation
Safety Analysis
Reactor Calculations