The evaluation of postulated initiating events of RSG-GAS using HAZOP method.

The G.A Siwabessy Multipurpose Reactor (RSG-GAS) is one of three research reactors in Indonesia used for radioisotope production, experimental activities, and training. One of the risks of a nuclear reactor, including a research reactor, is the possibility of radioactive release into the environment. PSA Level 1 quantifies the core damage frequency (CDF) for a postulated initiating event (PIE). IAEA has published the safety series SSR-3 that provides examples of selected PIE for research reactors, but each reactor may have other PIE depending on the characteristics of the design. PIEs for RSG-GAS are defined solely based on the manufacturer's data and have never been systematically evaluated. Hence, it is necessary to systematically evaluate those pre-defined PIEs. This study aims to evaluate the PIEs of the RSG-GAS secondary cooling system using the HAZOP method. It is important because the possibility of the reactor temperature could increase if the secondary cooling system fails to remove heat from the core, and, hence, can cause radioactive substances released into the environment if the secondary cooling system leakage and the protective measures are failed. This study evaluated 7 possible events and the results show that all events have low risk, low consequence, and/or rare frequency. Therefore, those 7 events did not meet the PIE criteria. Nevertheless, we still recommend that RSG-GAS pay attention to those identified events and provide additional procedures to periodically check the radioactivity concentration in the secondary water when PA-01/PA-02 CR 001 is activated. [ABSTRACT FROM AUTHOR]