Thermal neutron scattering cross sections of thorium hydride

An ab initio approach is used to calculate the phonon frequency distribution of thorium hydride (ThH2). The scattering law and the thermal neutron scattering cross sections for Th and H have been generated using this distribution. Due to the lack of experimental data, the results have been compared to zirconium hydride (ZrH2) data that were generated using a classical lattice dynamics model. Based on this comparison, it is shown that the differences in properties of ThH2 and ZrH2 are entirely consistent with the physical differences between the two materials. Consequently, this work provides a set of data that is useful in nuclear reactor technology, and illustrates the utility of the ab initio approach as a unique predictive tool of the properties of materials that are of interest to nuclear reactor design. (authors)