Theoretical study of thermal neutron scattering by light and heavy water with molecular dynamics simulation

Ichihara, Akira ; Abe, Yutaka*

Light and heavy water are being used as moderators in fission reactors. Reliable data of thermal neutron scattering in these materials is essential to the analysis of reactor cores. In this study we tried to evaluate angular distribution and energy spectrum of emitted neutrons employing the information obtained from molecular dynamics simulations. The simulations have been performed for light and heavy water. The thermal neutron scattering has been evaluated by using the fluctuation-dissipation theorem of statistical mechanics, where the trajectory data for hydrogen, deuterium and oxygen atoms were utilized. In calculation, incoherent scattering was assumed to be dominant in light water, while both the coherent and incoherent scattering contributions were considered in heavy water.