Sump Pool Flow Simulation during Fill-up Phase of LOCA Using on CFD for OPR1000 Plant

During LOCA (Loss of Coolant Accident) in design bases accident (DBA), emergency core coolant supplements form a recirculation sump and cooled core and containment. When the double ended guillotine Break (DEGB) at the hot leg near steam generator, due to the jet impingement discharge flow, the debris could be potentially generated at pipe or wall nearby steam generator and be transported to the recirculation sump. Therefore, the debris, such as insulations and paint chips, could be accumulated and be clogged in the recirculation sump screen. If debris is blocked the sump strainer, the pressure drop is increased at the screen so as to increase the pressure loss of ECCS (Emergency Core Cooling System) pump NPSH (Net positive suction head). It is potentially influenced to decrease the long-term cooling capability of the recirculation sump. The recirculation sump screen clogging accident has happened in BWR of USA and Sweden. Considering the important to safety, US NRC (Nuclear Safety Commission) has issued the recirculation sump blockage as GSI-191(Generic Safety Issue-191). Moreover, US NRC published Regulatory Guide 1.82 Rev.3 incorporated the R and D findings and experiences in 2003. NEI (Nuclear Energy Institute) introduced the methodology procedure to solve this safety issue in the NEI 04-07 report. In the meanwhile, US NRC also published individually the regulatory guidelines as a SER (Safety Evaluation Report) report for PWR plant. However, the current available technical information including the reports is applicable to the generic PWR plants not the plant specific plant. Therefore, the additional research reflecting characteristics of plant specific plant is necessary to develop the methodology and technical guides on the recirculation sump clogging issue. The objective of this study is addressed to explore the characteristics of sump pool flow during LOCA by using CFD for the OPR1000 plant