Preliminary design and assessment of a novel passive residual heat removal system for the pool-vessel reactor system

A novel PRHRs combining the traditional C-type heat exchanger and two-phase loop thermosyphon (TPLT) heat exchangers is proposed for long-term passive cooling of a typical pool-vessel reactor system. The selection of the working fluid in the thermosyphon and parameters of the main components are described in detail. A system model of the PRHRs is established using the RELAP5 code, and numerical analyses are carried out. The response characteristics of the system with and without the TPLT in operation are compared. Sensitivity analysis is conducted for three representative design parameters. The results show that the PRHRs can provide sufficient heat removal capacity after its implementation and significantly reduce the temperature levels of the reactor primary circuit and the reactor pool. Moreover, the three design parameters have a significant impact on the system's operation and affect the system in different ways, which should be considered in the subsequent optimization of the system.