Calculation and Analysis of Thermal Scattering Law of Zirconium Hydride Based on First-principles Calculation

Abstract

Phonon density of states (DOS) is the basic input parameter to calculate the thermal scattering law data. Different concentrations of hydrogen in zirconium hydride (ZrHx) lead to various lattice structures, and then affect the phonon DOS. In the world, the parameterized mathematical formula of phonon DOS is usually obtained by fitting the experimental results, which cannot reflect the real lacttice structure of ZrHx. In this paper, the first-principles calculation was used to obtain the phonon DOS based on the lattice structures of δ-ZrH1.5 and ε-ZrH2. The impacts of the phonon DOS obtained by different methods on thermal scattering cross sections, and further the reactivity of several TRIGA reactors containing ZrHx were investigated. The numerical results show that, compared with the phonon DOS used in ENDF/B-Ⅷ.0 and JEFF-3.3 evaluated nuclear data files, more accurate scattering cross sections and the neutronics results of TRIGA reactors can be obtained by the first-principles calculated phonon DOS.