Study of rescue measure of Kuosheng BWR power plant to cope with Fukushima-type accident

Highlights: • The ultimate response guidelines were developed to cope with the Fukushima-type event. • The MAAP5 and RELAP5 models were used to assess the effectiveness of the guidelines. • The sensitivity studies for the depressurization of the reactor pressure vessel were done. • The MAAP5 simulations were compared with the RELAP5 calculations. - Abstract: Because of the accident in the Fukushima Dai-ichi nuclear power plant on March 11, 2011, the Taiwan Power Company developed the ultimate response guidelines for the owned nuclear power plants to cope with the Fukushima-type event. The guidelines had the DIVing strategy to prevent the core damage, the hydrogen generation, and the public evacuation. The strategy performed the depressurization and injection of the reactor pressure vessel and the venting of the containment simultaneously to keep the peak cladding temperature of the core fuels below 1500 °F (1088.7 K) The MAAP5 and RELAP5 models of the Kuosheng BWR/6 nuclear power plant of the Taiwan Power Company were used to assess the effectiveness of the guidelines. Based on the results of the code calculations, it was concluded that the guidelines could be used successfully to cope with the Fukushima-type event. And according to the results of the comparisons, the MAAP5 simulations were similar to the RELAP5 calculations. Based on the RELAP5 simulation results, if three safety relief valves were used to do the vessel controlled depressurization, the peak cladding temperature of the core fuels might increase and the concern of the core fuel safety might be needed. According to the sensitivity study results, if the initiation pressure of the vessel emergency depressurization was higher than 40 kgf/cm² (4.03 MPa), the minimum vessel alternate water injection flow would have the significant increase.