Abstract: Many lessons can be learned from the Fukushima Daiichi Nuclear Power Plant accident. First, if an isolation condenser (IC) continues to operate, the accident would be terminated soon. A reactor core isolation cooling (RCIC) steam turbines also stopped due to loss of battery power in Units No.2 and No.3. suppression pool (S/P) temperature and pressure were so high that the accident management water injection took too long time. After the loss of ECCS and IC core cooling, Containment Vessel pressure increased. Hydrogen explosion occurred after venting. The analysis results show that the depressurization of the reactor pressure vessel (RPV) started before RPV bottom failure. It is hoped that the lessons learned from this accident will help to improve the safety of nuclear power plants worldwide.

Keyword: nuclear safety; Fukushima Daiichi; severe accident; tsunami, station blackout