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Thermal neutron scattering cross sections of 238U and 235U in the γ phase.
J Phys Condens Matter 2018; 30(41):415401JP

Abstract

The development of metallic, low-enrichment uranium fuels requires accurate prediction of their neutron transport properties and reactivity parameters, which in turn require thermal neutron scattering data. Accurate prediction of thermal neutron scattering data, including thermal cross sections, requires knowledge of the phonon scattering properties of the medium, but such matrix binding effects in next-generation fuels such as U-Mo, U-Zr, and U-Si are typically neglected because these effects are often difficult to measure or calculate. Using molecular dynamics simulations with previously published interatomic potentials, we calculate the phonon dispersion relations and phonon densities of states for 235U and 238U in the α and γ phases. The performance of these potentials was evaluated using published ab initio simulation data and inelastic neutron scattering data. The phonon densities of states obtained by each potential were then utilized to calculate the thermal neutron scattering cross sections of 235U and 238U at 1113 K using the NJOY program. The resulting thermal neutron scattering cross sections are assessed by comparison to data obtained from available experimental densities of states. The cross sections generated show how the addition of binding effects decreases the cross section by up to a factor of six over the free-atom model. A definite effect on reactivity is also demonstrated by the use of these thermal libraries on a simple core model. As a consequence, the cross sections generated in this work provide a better description of the true cross section than the free-atom data currently available. We also discuss the sensitivity of the thermal scattering cross sections to the phonon density of states.

Authors+Show Affiliations

Nuclear Engineering Program, University of Missouri, Columbia, MO 65211, United States of America.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30129564

Citation

Saltos, Andrea A., et al. "Thermal Neutron Scattering Cross Sections of 238U and 235U in the Γ Phase." Journal of Physics. Condensed Matter : an Institute of Physics Journal, vol. 30, no. 41, 2018, p. 415401.
Saltos AA, Peters NJ, Hammond KD. Thermal neutron scattering cross sections of 238U and 235U in the γ phase. J Phys Condens Matter. 2018;30(41):415401.
Saltos, A. A., Peters, N. J., & Hammond, K. D. (2018). Thermal neutron scattering cross sections of 238U and 235U in the γ phase. Journal of Physics. Condensed Matter : an Institute of Physics Journal, 30(41), p. 415401. doi:10.1088/1361-648X/aadbc8.
Saltos AA, Peters NJ, Hammond KD. Thermal Neutron Scattering Cross Sections of 238U and 235U in the Γ Phase. J Phys Condens Matter. 2018 Oct 17;30(41):415401. PubMed PMID: 30129564.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thermal neutron scattering cross sections of 238U and 235U in the γ phase. AU - Saltos,Andrea A, AU - Peters,Nickie J, AU - Hammond,Karl D, Y1 - 2018/08/21/ PY - 2018/8/22/pubmed PY - 2018/8/22/medline PY - 2018/8/22/entrez SP - 415401 EP - 415401 JF - Journal of physics. Condensed matter : an Institute of Physics journal JO - J Phys Condens Matter VL - 30 IS - 41 N2 - The development of metallic, low-enrichment uranium fuels requires accurate prediction of their neutron transport properties and reactivity parameters, which in turn require thermal neutron scattering data. Accurate prediction of thermal neutron scattering data, including thermal cross sections, requires knowledge of the phonon scattering properties of the medium, but such matrix binding effects in next-generation fuels such as U-Mo, U-Zr, and U-Si are typically neglected because these effects are often difficult to measure or calculate. Using molecular dynamics simulations with previously published interatomic potentials, we calculate the phonon dispersion relations and phonon densities of states for 235U and 238U in the α and γ phases. The performance of these potentials was evaluated using published ab initio simulation data and inelastic neutron scattering data. The phonon densities of states obtained by each potential were then utilized to calculate the thermal neutron scattering cross sections of 235U and 238U at 1113 K using the NJOY program. The resulting thermal neutron scattering cross sections are assessed by comparison to data obtained from available experimental densities of states. The cross sections generated show how the addition of binding effects decreases the cross section by up to a factor of six over the free-atom model. A definite effect on reactivity is also demonstrated by the use of these thermal libraries on a simple core model. As a consequence, the cross sections generated in this work provide a better description of the true cross section than the free-atom data currently available. We also discuss the sensitivity of the thermal scattering cross sections to the phonon density of states. SN - 1361-648X UR - https://www.unboundmedicine.com/medline/citation/30129564/Thermal_neutron_scattering_cross_sections_of_238U_and_235U_in_the_γ_phase L2 - https://doi.org/10.1088/1361-648X/aadbc8 DB - PRIME DP - Unbound Medicine ER -