Speaker
Description
Graphite has been of significant scientific interest since the inauguration of nuclear technology, through the search for a high-purity grade to be used as a neutron moderator in Chicago-Pile 1, the first nuclear reactor. Currently, the Very High-Temperature Gas-Cooled Reactor is graphite-moderated and uses graphite as a significant structural component. Furthermore, nuclear graphite is a critical component of other Generation IV reactors concepts, such as the Fluoride Salt-Cooled High-Temperature Reactor. Vibrational properties and neutron thermalization in graphite have been studied extensively over the past few decades both computationally and experimentally. In this work, we report the room temperature inelastic neutron scattering measurements of the scattering function, double differential scattering cross-sections, and the full phonon density of states of nuclear graphite using the time-of-flight wide Angular-Range Chopper Spectrometer at the Spallation Neutron Source at Oak Ridge National Laboratory. We also will present the first-principles phonon calculations of graphite as well as the scattering function and inelastic scattering thermal neutron scattering cross-sections at different temperatures. This work aims to provide a new presentation of neutron thermalization on nuclear graphite and offers a new set of high-quality experimental and computational data for consideration.
Acknowledgment
The experimental material is based upon work that was conducted by I. I. Al-Qasir while a Visiting Research Fellow at the Shull-Wollan Center- the University of Tennessee and Oak Ridge National Laboratory’s Joint Institute for Neutron Sciences. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. I. I. Al-Qasir acknowledges the use of the HPC Facility at the University of Sharjah to perform the density functional theory calculations.