A study of criticality and thermal loading in a conceptual micronuclear heat pipe reactor for space applications

Abstract

Neutronic analysis of a conceptual heat pipe-cooled micronuclear reactor with 70 % enriched uranium nitride fuel is carried out by modeling the core and peripheral control drum movement to estimate the power distribution. The core configuration results in non-uniformities and hotspots. For the heat removal, empirical formulae have been used in the case of sodium, lithium, and potassium working fluids. The neutronic simulation was carried out by the OpenMC code. It has been found that the radial flux peaking as high as ~20 % can occur at various stages of the drum movement. The novelty of this research is the investigation of the effect of variable enrichment on the overall system multiplication, which can form the basis for optimal fuel distribution. It has been found that non-uniform fuel distribution can mitigate peaking factors, and thus reduce the hotspots. This analysis is useful for the design optimization of compact micro nuclear reactors for underwater, portable and space propulsion systems.