Conceptual Design of a Micro Nuclear Energy System With Integrated Heat Pipe Cooled Reactor and Molten Salt Heat Storage

Abstract

Micro nuclear energy system has the advantages of low investment and flexible deployment, which contribute to wide application prospects. However, in comparison to the large nuclear power plants, micro nuclear energy system is situated closer to users and requires higher safety performance. This paper proposes a new conceptual design of a micro nuclear energy system with high thermal inertia. It is based on a heat pipe cooled reactor and an integrated heat storage system along with a supercritical carbon dioxide (SCO₂) Brayton cycle. The system can achieve 34.45% energy conversion efficiency and 1.2 MW electric power output. A heat pipe cooled reactor with uranium dioxide (UO₂) fuel and sodium heat pipe was designed. It was connected by the condensation section of heat pipes to a molten salt heat storage system. The SCO₂ Brayton cycle was used to ensure a compact system layout. Using a newly developed analysis platform, three transient conditions including the load reduction, reactivity insertion, and loss of heat sink were discussed. The results indicate that, with the intermediate heat storage, the micro nuclear energy system has better tolerance of the transient thermal shocks. The peak temperature in the core is reduced for all conditions. Particularly in the process of loss of heat sink, the peak temperature in the core can be reduced by more than 70 K.