[2F05-08] Safety Measures

[2F05] Risk of Japanese PWR Plants by shutting off forced core cooling at an accident

Comparison of reactor coolant pumps stop method on receiving of SI actuation signals in Japan, the US and Europe

*Yoshitaka Yoshida¹ (1. Research Institute of Nuclear Engineering, University of Fukui)

Keywords:PWR, Small break LOCA, Forced core cooling, Reactor coolant pump, Safety Injection

In the US and Europe, Westinghouse type plants manually stop the RCPs according to the judgment criteria if the high pressure injection system is operating at the time of small break LOCA. For the pressure equalization operation during SGTR, the pressurizer spray is using as same as normal operation. European KONVOI and EPR plants automatically stop the RCPs on receiving of SI actuation signals, and automatically open the main steam relief valves to cooldown and depressurize at 100 °C/h. Furthermore, the pressure equalization operation during SGTR is designed to reduce the discharge pressure of the high pressure injection system to the secondary no-load pressure. On the other hand, the Japanese PWR plants automatically stop the RCPs on receiving of SI actuation signals, and manually full opens the main steam relief valves to cooldown and depressurize. Furthermore, the pressure equalization operation during SGTR relies on the pressurizer relief valve and pressurizer auxiliary spray. The comparison results of these designs will be described.