A study for effects of rod power and flooding rate on the RELAP5/MOD3 assessment of FLECHT SEASET

FLECHT SEASET unblocked forced reflood tests are assessed using Apollo version of RELAP5/MOD3 5M5. The main purpose of the study is to examine the code predictability under forced reflood conditions having different initial power levels and flooding rates. Among various test matrices, the assessment calculations are performed for the eight cases. These cases have been selected because they have similar initial conditions but different initial peak rod powers of flooding rates. The assessment results show that the RELAP5/MOD3 has a tendency to underpredict the turn around temperature and the turn around time. However, RELAP5/MOD3 slightly overpredicts turn around temperature for high flooding rate. The results also show that the calculated quenching time by RELAP5/MOD3 is delayed with the increase of the rod power or the decrease of the flooding rate