ROSA/LSTF test on PWR station blackout transient with loss of primary coolant and RELAP5 analysis

Takeda, Takeshi ; Otsu, Iwao 

The effectiveness of accident management measure should be confirmed in case of PWR station blackout transient with loss of primary coolant. A simulation experiment with the ROSA/LSTF was thus conducted under an assumption of nitrogen gas inflow into the primary system. After the nitrogen gas inflow, the primary depressurization rate became smaller and non-uniform flow behavior was observed among steam generator (SG) U-tubes. In addition, RELAP5/MOD3.2 code indicated remaining problems in the predictions of the primary pressure and SG U-tube liquid level after the nitrogen gas inflow through the post-test analysis.