Study on the flow rate and actuation time of emergency injection into RCS during severe accident

Injecting water into RCS is one of the most effective actions to mitigate the progression of a core damage accident. After Fukushima accident, China National Nuclear Safety Administration (NNSA) requires that nuclear power plants should add portable equipment for emergency injection. The flow rate and initiation time of emergency injection are studied in this paper. The results show that water injection into RCS timely can prevent the RPV failure effectively. Compared with the injection rate, the time at which injection is actuated is more important to the integrality of reactor vessel. Moreover, as the injection flow rate increase, the core can be flooded faster, but the flow rate has little influence on the core exit temperature, hydrogen generation and fission product release. (authors)