Abstract
The Hybrid Propulsion Engine and Reactor Impulse for Orbital Navigation (HYPERION) is an advanced space reactor concept for the power and propulsion of the next generation of spacecraft. Developed at the Universities Space Research Association, Center for Space Nuclear Research, HYPERION aims to be the next giant leap in spacecraft propulsion, integrating both nuclear electric and nuclear thermal propulsion for regret-free maneuvering throughout the Solar System. HYPERION achieves this by harnessing gaseous Uranium Hexafluoride (UF6) nuclear fuel, brought to criticality within the reactor by a sophisticated neutron reflector and pressurization system.This thesis explores the materials and simulation of potential neutron reflectors for the HYPERION concept by investigating the efficacy of Deuterium Oxide (D2O) through Monte Carlo simulations and comparing its neutronics performance against beryllium-based reflector materials (Be, BeO, Be2C). The simulations progress from simple spherical and toroidal geometries assessing the critical mass of the fuel and neutron energy spectrum for each material, culminating in a complex computer-aided design-based simulation using the open-source Monte Carlo software OpenMC. Through these simulations, it is determined that not only does D2O make an excellent reflector neutronically, but it also reduces the overall system mass of the prototype design by 20.19% on the low end and up to 39.14% on the high end.