Speaker
Description
The thermal scattering laws (TSLs) take into account the crystalline structure and atomic motions of isotopes bound in materials. This paper presents the CINEL code, which was developed to generate temperature-dependent TSLs for solid, liquid and free gas materials of interest for nuclear reactors.
CINEL is able to calculate TSLs from the phonon density of states (PDOS) of materials under the Gaussian-Incoherent approximations. The PDOS can be obtained by using theoretical approaches (e.g., ab initio density functional theory and molecular dynamics) or experimental results. In this work, the PDOS presented in the ENDF/B-VIII.0 database [1] and the NJOY-NCrystal library [2] were used for numerical validation purposes. The CINEL results are in good agreement with those reported in these databases, even in the specific cases of TSLs with the newly mixed elastic format.
The coding flexibility offered by Python using the JupyterLab interface allowed to investigate limits of physical models reported in the literature, such as a four-site model for UO2, anharmonic behaviors of oxygen atoms bound in a Fm3m structure, texture in Zry-4 samples and jump corrections in a roto-translational diffusion model for liquid water. The use of graphic processing units (GPU) is a necessity to perform calculations in a few minutes.
The performances of the CINEL code will be illustrated with the results obtained on actinide oxides having a Fm3m structure (UO2, ThO2, NpO2 PuO2 and AmO2), low enriched fuel (U3Si2, UMo, UZrH) and moderators (H2O with a specific emphasis on ice).
References
[1] D.A. Brown et al. “ENDF/B‐VIII.0: The 8th Major Release of the Nuclear Reaction Data Library with CIELO‐project Cross Sections, New Standards and Thermal Scattering Data”. In: Nuclear Data Sheets 148 (2018).
[2] Kemal Ramic et al. NJOY+NCrystal: an open‐source tool for creating thermal neutron scattering libraries. 2021. https://arxiv.org/pdf/2108.11737.pdf