Evaluating the core damage frequency of a TRIGA research reactor using risk assessment tool software

After all preventive and mitigative measures considered in the design of a nuclear reactor, the installation still represents a residual risk to the outside world. Probabilistic safety assessment (PSA) is a powerful method to survey the safety of nuclear reactors. In this study the occurrence frequency of different types of core damage states (CDS) which may potentially arise in Tehran Research Reactor (TRR) is evaluated by use of the recently developed risk assessment tool (RAT) software which has been designed and represented in the Safety Research Center of Shiraz University. RAT uses event trees and fault trees to evaluate the total final core damage frequency (CDF) through studying the frequencies of initiation events, and following their consequences has resulted in one type of the CDS. The criterion must be of the order of smaller than 1E−04 through IAEA standards for research reactors (IAEA-TECDOC-400, 1986). Results show that the total final CDF for TRR is of the order of 10−6, which meets the criterion of nuclear research reactor.

• In this study, level-I PSA is performed, to reveal and modify the weak points threatening the safe operation of a typical TRIGA reactor. • After identification of the initiating events and developing the appropriate event trees and fault trees, by the risk assessment tool interface, the core damage frequency has been estimated to be 8.368E−6 per year of reactor operation, which meets the IAEA standards. • The results also indicate the significant effects of the common cause failures.