Investigation of quenching phenomena during the relooding phase against the FLECHT-SEASET experiment by using RELAP5/MOD3.3

The reflood model of RELAP5/MOD3.3 (patch 4) was assessed by using the FLECHT-SEASET tests. The tests were conducted to have a better understanding of the postulated loss of coolant accident in a light water reactor (LWR). The best-estimate system analysis code was used to simulate these accident scenarios, especially in Design Basic Accident such as Loss-Of-Coolant-Accident (LOCA). The primary purpose of this report was to assess the accuracy of a computer system analysis code by using RELAP5/MOD3.3 in comparison to actual test results taken from the FLECHT-SEASET tests in which the reflood model was built in. In RELAP5’s simulation cases, the various boundary and initial conditions, such as power supplied and reflooding rate were selected. As a result, the RELAP5 looked to be accurate in predicting the quenching time and rod surface temperature for this particular case. However, the RELAP5 code under-estimated the rod surface temperature in comparing with the experimental data of the FLECHT-SEASET tests. Accordingly, for this high flooding rate and particular reactor power level that the reflooding model in RELAP5 could be possible used for predicting the reflooding phenomena during the LOCA accident.