Loss of Off Site Power Accident Analysis Probabilistic and Deterministic Approach

The accident analysis of a reactor should consider analysis of Design Base Accidents DBA . One of these accident is the Loss of Off Site Power LOSP. For Egypt, the LOSP frequency is abnormally high; 10 times/year, this gives a good cause for initiating the present work. The present work adopted both the probabilistic and the deterministic methods to determine the likelihood of the accident and to establish and assertion of the variation of the reactor safety related parameters e.g. power, flow and temperature over the prescribed accident evolution time. The accident scenario covers the failure sequences of the Reactor Safety systems. Four generated LOSP accident scenarios are analyzed. Two codes are used, the first is the IAEA Probabilistic Safety Assessment Package PSAPACK, the second TR22M21 has been developed by the author to simulate the expected behavior of the reactor thermal-hydraulic parameters. It has been found that the two codes have successfully identify a severe scenario with annual occurrences frequency of 3.8 E-5 which could significantly contribute to the risk of the core damage