Parametric Trade Space Investigation of Particle Bed Reactors for Nuclear Thermal Propulsion

Nuclear thermal propulsion (NTP) systems utilizing particle bed reactors (PBR) offer performance advantages over traditional NTP propulsion system designs. In addition to low pressure drop requirements through the reactor, PBRs can deliver high power density, potentially leading to lower mass designs. This work seeks to investigate various design points of PBR-based NTP systems. The DOD Space Nuclear Thermal Propulsion (SNTP) PBR design is a template for the trade space investigation. Parameter sweeps of core length, particle radius, system mass flow rate, packing fraction, bed thickness, and many other variables inform point design definitions. Coupled multiphysics modeling methodology yields data on the performance of design points, while ruling out any infeasible configurations. This study captures the mass and performance trades of feasible PBR designs.

A PBR trade space database is generated and reveals that for a given thrust class, the SNTP-derived designs offer low mass, critical reactor options with reduced pressure drop requirements while using high-assay low-enriched uranium fuel. A comparison of the trade space summarizes the performance capabilities of PBR NTP reactors.