ROSA/LSTF experiment on accident management measures during a PWR station blackout transient with pump seal leakage and RELAP5 analyses

PWRポンプシール部の漏洩を考慮した全電源喪失時のアクシデントマネジメント策に関するROSA/LSTF実験とRELAP5コード解析

竹田 武司 ; 大津 巌 

Takeda, Takeshi; Otsu, Iwao

An experiment on accident management (AM) measures during a PWR station blackout transient with leakage from primary coolant pump seals was conducted using the ROSA/LSTF under an assumption of non-condensable gas inflow to the primary system from accumulator tanks. The AM measures 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 and coolant injection into the SG secondary-side at low pressures. 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 accumulator completion. Remaining problems in the RELAP5 code include the predictions of pressure difference between the primary and SG secondary sides after the gas inflow.