Systematic Design of Passive ln-core Cooling System Based on Hybrid Control Rod-Heat Pipe for Small Modular Reactor

摘要

Guarantee of the diversity by installation of additional safety system, having different working principle from the existing systems, could mitigate the suggested issues on the passive safety systems. Hybrid control rod-heat pipe, which is a passive decay heat removal device combining the functions of heat pipe and control rod, was proposed by UNIST in Republic of Korea as a passive safety system improving the diversity of passive safety in small modular reactors. It was designed to perform both functions of decay heat removal and reactivity control simultaneously. From the performance analysis, it was found that the designed hybrid control rod has sufficient decay heat removal capacity and reactivity worth. Additionally, hydraulic control rod drive mechanism, which controls the movement of control rod by hydraulic resistance, was designed to achieve fully-passive operation of the hybrid control rods eliminating the malfunction of CRDM owing to electromagnetic signal error. Based on the feasibility study for the concept of hybrid control rod and hydraulic control rod drive mechanism, detailed design of passive in-core cooling system (PINCs) for SMR consisting of hybrid control rods, hydraulic control rod drive mechanism, and heat sinks, was constructed considering the operations of PINCs during normal and accident conditions of reactor.