Loss of offsite power (LOOP) accident analysis by integration of deterministic and probabilistic approaches in Bushehr-1 VVER-1000/V446 nuclear power plant

The results of an accident analysis for the loss of offsite power (LOOP) scenario in a reference Bushehr-1 VVER-1000/V446 nuclear power plant (NPP) are presented in this paper. This study attempted to provide a better analysis of LOOP accident management by integrating deterministic and probabilistic approaches. The RELAP5 code was used to investigate the occurrence of specific thermal–hydraulic phenomena. The probabilistic safety assessment of the LOOP accident is presented using the SAPHIRE software. LOOP accident data were extracted from the Bushehr NPP final safety analysis reports and probabilistic safety analysis reports. A deterministic approach was used to reduce the core damage frequency in the probabilistic analysis of LOOP accidents. The probabilistic approach was used to better observe the philosophy of defense in depth and safety margins in the deterministic analysis of the LOOP accident. The results show that the integration of the two approaches in LOOP accident investigations improved accident control.