Preliminary conceptual design of a moderated micro nuclear reactor core cooled by heat pipe

Abstract

A micro nuclear reactor cooled by heat pipe (HP) is a potential option to provide reliable and cost-effective electrical power. It can be used for remote mining operations and multitudes of remote civilian communities. The fast reactor concept is usually adopted in the previous designs in which the fuel inventory is high. Their fuel cycle performance is not satisfactory. A conceptual design of a moderated micro nuclear reactor cooled by heat pipe (MHPR) is proposed in the current study. Its concept is established with a softened neutron spectrum which may improve the utilization of thermal neutrons and reduce fuel inventory. One of the most famous Monte Carlo codes OpenMC is employed to optimize the geometry and mass of the proposed MHPR. A parametric analysis is carried out to provide reference values for P/D ratio, enrichment, etc., based on a systematic study of different unit cells. The simulation results also prove that the core mass can be significantly reduced due to the moderation effect by ZrH1.8. Based on this optimization analysis, a detailed design of MHPR is also proposed. Its total thermal power is 3.5 MWt with a core lifetime of 8.2 years without refueling. The calculated results show that the proposed design satisfies the shutdown margins with two different control strategies. It is also revealed that if the HP power can be increased in the future, a much smaller and lighter reactor core can be achieved.