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Evaluation of δ-Phase ZrH1.4 to ZrH1.7 Thermal Neutron Scattering Laws Using Ab Initio Molecular Dynamics Simulations

Mehta, Vedant ; Rehn, Daniel and Olsson, Pär LU (2024) In Journal of Nuclear Engineering 5(3). p.330-346
Abstract
Zirconium hydride is commonly used for next-generation reactor designs due to its excellent hydrogen retention capacity at temperatures below 1000 K. These types of reactors operate at thermal neutron energies and require accurate representation of thermal scattering laws (TSLs) to optimize moderator performance and evaluate the safety indicators for reactor design. In this work, we present an atomic-scale representation of sub-stoichiometric ZrH2−x (0.3≤𝑥≤0.6)(0.3≤x≤0.6), which relies on ab initio molecular dynamics (AIMD) in tandem with velocity auto-correlation (VAC) analysis to generate phonon density of states (DOS) for TSL development. The novel NJOY+NCrystal tool, developed by the European Spallation Source community, was... (More)
Zirconium hydride is commonly used for next-generation reactor designs due to its excellent hydrogen retention capacity at temperatures below 1000 K. These types of reactors operate at thermal neutron energies and require accurate representation of thermal scattering laws (TSLs) to optimize moderator performance and evaluate the safety indicators for reactor design. In this work, we present an atomic-scale representation of sub-stoichiometric ZrH2−x (0.3≤𝑥≤0.6)(0.3≤x≤0.6), which relies on ab initio molecular dynamics (AIMD) in tandem with velocity auto-correlation (VAC) analysis to generate phonon density of states (DOS) for TSL development. The novel NJOY+NCrystal tool, developed by the European Spallation Source community, was utilized to generate the TSL formulations in the A Compact ENDF (ACE) format for its utility in neutron transport software. First, stoichiometric zirconium hydride cross sections were benchmarked with experiments. Then sub-stoichiometric zirconium hydride TSLs were developed. Significant deviations were observed between the new δ-phase ZrH2−x TSLs and the TSLs in the current ENDF release. It was also observed that varying the hydrogen vacancy defect concentration and sites did not cause as significant a change in the TSLs (e.g., ZrH1.4 vs. ZrH1.7) as was caused by the lattice transformation from ϵ- to δ-phase. (Less)
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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
thermal scattering law, zirconium hydride, NJOY, NCrystal
in
Journal of Nuclear Engineering
volume
5
issue
3
pages
17 pages
publisher
MDPI AG
ISSN
2673-4362
DOI
10.3390/jne5030022
language
English
LU publication?
yes
id
507706b1-aa49-4baa-b91b-c6bf6c98cf54
date added to LUP
2024-09-13 11:45:51
date last changed
2024-09-17 15:20:25
@article{507706b1-aa49-4baa-b91b-c6bf6c98cf54,
  abstract     = {{Zirconium hydride is commonly used for next-generation reactor designs due to its excellent hydrogen retention capacity at temperatures below 1000 K. These types of reactors operate at thermal neutron energies and require accurate representation of thermal scattering laws (TSLs) to optimize moderator performance and evaluate the safety indicators for reactor design. In this work, we present an atomic-scale representation of sub-stoichiometric ZrH<sub>2−x</sub> (0.3≤𝑥≤0.6)(0.3≤x≤0.6), which relies on ab initio molecular dynamics (AIMD) in tandem with velocity auto-correlation (VAC) analysis to generate phonon density of states (DOS) for TSL development. The novel NJOY+NCrystal tool, developed by the European Spallation Source community, was utilized to generate the TSL formulations in the A Compact ENDF (ACE) format for its utility in neutron transport software. First, stoichiometric zirconium hydride cross sections were benchmarked with experiments. Then sub-stoichiometric zirconium hydride TSLs were developed. Significant deviations were observed between the new δ-phase ZrH<sub>2−x</sub> TSLs and the TSLs in the current ENDF release. It was also observed that varying the hydrogen vacancy defect concentration and sites did not cause as significant a change in the TSLs (e.g., ZrH<sub>1.4</sub> vs. ZrH<sub>1.7</sub>) as was caused by the lattice transformation from ϵ- to δ-phase.}},
  author       = {{Mehta, Vedant and Rehn, Daniel and Olsson, Pär}},
  issn         = {{2673-4362}},
  keywords     = {{thermal scattering law; zirconium hydride; NJOY; NCrystal}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{3}},
  pages        = {{330--346}},
  publisher    = {{MDPI AG}},
  series       = {{Journal of Nuclear Engineering}},
  title        = {{Evaluation of δ-Phase ZrH<sub>1.4</sub> to ZrH<sub>1.7</sub> Thermal Neutron Scattering Laws Using Ab Initio Molecular Dynamics Simulations}},
  url          = {{https://lup.lub.lu.se/search/files/195104023/jne-05-00022.pdf}},
  doi          = {{10.3390/jne5030022}},
  volume       = {{5}},
  year         = {{2024}},
}