Abstract
An experiment on accident management (AM) measures during a PWR station blackout (SBO) transient with the TMLB' scenario and leakage from primary coolant pump seals was conducted using the ROSA/large scale test facility (LSTF) at Japan Atomic Energy Agency under an assumption of non-condensable gas inflow to the primary system from accumulator (ACC) tanks. The AM measures considered in this study are steam generator (SG) secondary-side depressurization by fully opening safety valves (SVs) in both SGs and primary-side depressurization by fully opening SV in pressurizer with the start of core uncovery as well as coolant injection into the secondary-side of both SGs at low pressures. The LSTF test revealed that the decrease was accelerated in the primary pressure when the SG primary-to-secondary heat removal resumed soon after the coolant injection into the SG secondary-side. The primary depressurization worsened due to the gas accumulation in the SG U-tubes after the completion of ACC coolant injection. The RELAP5 code well predicted the overall trend of the major phenomena observed in the LSTF test, and indicated remaining problems in the predictions of the primary pressure and SG U-tube collapsed liquid level. Influences of the pump seal leakage onto major phenomena until the start of the AM measures were investigated through comparison with results of the authors' previous test on the SBO (TMLB') transient without the pump seal leakage.
