Study on the behavior of reactor core isolation cooling system (RCIC) under severe accident condition

The Fukushima Daiichi Nuclear Station accident (hereinafter Fukushima Daiichi accident) revealed the risks that had not been envisaged in the past, but on the other hand, there were the devices that were unexpectedly effective for safety, one of which was a reactor core isolation cooling system (RCIC). RCIC is a system that when the BWR core is isolated from the main turbine, the RCIC's turbine is started instead of the main turbine, and cooling water is injected into the core with the power obtained from it. Although the design operation time is about 8 hours, in the Fukushima Daiichi accident, core cooling was performed for about 20 hours for Unit 3, and for about 66 hours for Unit 2. From the experience of the Fukushima Daiichi accident, the safety re-evaluation of RCIC has a possibility to increase the safety of reactors without requiring additional costs. So, a joint project "Study on the behavior of reactor core isolation cooling system (RCIC) under severe accident condition" is under promotion in cooperation with the U.S. Sandy National Laboratory. Experiments will be conducted mainly for the purpose of driving a full-scale turbine with steam, and important data for understanding the characteristics of the turbine will be obtained. (A.O.)