Identification of initiating events for pressurized water reactor accidents using a probabilistic approach

Once an event in a pressurized water reactor (PWR) occurs and the operator has identified it, the system may then be returned to safe operational status. Usually, monitoring the thermal state of the reactor, e.g., the temperature and pressure of the reactor cooling system (RCS), allows the operator to recognize an event in progress. In this study, the temperature difference between hot and cold legs and the pressure of the steam generator (SG) are also adopted as the parameters relative to identification. The event data are generated by the best estimated model RELAP5. The cumulative distribution function (CDF) is constructed and the cumulative probability from 0.05 to 1.00, with 0.05 increments, are chosen for identification. Considering the measurement noise, the probabilistic approach is adopted. The random value is added to the simulated data, and then a 95% confidence interval is obtained. To identify an event, eighty data points, i.e., twenty data points for each parameter and four parameters for each event, should match the stored data. Since the identification procedure is simple, the process is very fast. This method will be beneficial in the context of executing an emergency operating procedure more effectively.

► Four system key parameters are adopted in the identification procedure.
► The identification procedure is simple, the process is very fast.
► This method will be beneficial in the context of executing an emergency operating procedure more effectively.