Study on the Fallback Time Analysis Method for Loss of Ultimate Heat Sink Under Normal Power Operation of Nuclear Power Unit Available to Purchase

For the beyond design basis accident, loss of ultimate heat sink under normal power operation of CPR1000 nuclear power unit, an analytical model is proposed to evaluate the process during which the component cooling system is cooled by the Refueling Water Storage Tank, which is very important for the accident treatment. The results of the analytical model agree well with that provided by EDF. Based on the according strategies of State-oriented Procedure, a fallback time analysis method is carried out, the result is in accordance with the simulation time on the full-scope simulator. These indicate that the analytical model for the cooling process and the fallback time analysis method are correct.