RETRAN-03 Simulation of a Multiple Failure Event at Kori Unit 2

A multiple failure event, a stuck-open pressurizer spray valve along with pressurizer pressure transmitter failure, which occurred on February 25, 1995, at Kori nuclear unit 2, is simulated using the best-estimate thermal-hydraulic computer code RETRAN03/MOD000. The simulation was performed to validate the predictive capabilities of RETRAN03 against plant data. The results would be useful in evaluation of the emergency operation procedures. The transient was simulated for 5000 s until the reactor coolant system pressure was stabilized and hot standby condition could be achieved. The simulation results and their corresponding plant data, especially for the evolutions of all the major thermal-hydraulic parameters, are compared and analyzed. Relatively good agreement between the plant data and the code prediction has been obtained; however, the simulation cannot duplicate the plant data for the low-flow condition that was encountered near the end of the transient.