Probabilistic safety assessment of the research reactor - TRIGA Mark II

The probabilistic safety analysis method was used to assess a risk level - associated with the research reactor TRIGA MARK II. The model of the reactor is presented by the system event trees for four initiating events. The system fault trees and the critical sequence event trees are reduced by means of the FTAP 2 program, and the quantitative evaluation was done by means of the IMPORT programme. The four initiating events selected were: LOCA, Loss of Electric Supply, Loss of Flow and Loss of flow-fuel Channel Blockage. For all four initiating events, event trees were constructed and the probability for core damage was calculated as well as the probability for the radioactive release. Most critical sequences were identified for each event trees and further analysed giving Importance measures (Im), Risk Reduction Rations (RRW) and Risk Achievement Rations (RAW). At the end, beside giving estimate about the risk level, some suggestions are given based on our results. (author)