MELCOR Application to LOCA Studies Effect of Safety ：该应用程序的安全分析研究的影响.ppt

MELCOR Application to Plant Accident Analyses at PSI Y. Liao, S. Guentay, J. Birchley, T. Haste Paul Scherrer Institute, Switzerland Outline Introduction to recent MELCOR applications at PSI Loss of RHR accidents during mid-loop operation LOCAs during hot shutdown operation LOCAs during full power operation Sensitivity study to the primary side nodalization Conclusions Introduction to recent MELCOR applications at PSI Beznau power plant: Two loop Westinghouse PWR 1130MW core thermal power Safety injection pumps: JSI 1-A, B,C,D Loss of RHR during mid-loop operation (22h after reactor trip) Initial conditions with core power at 0.57%FP, low primary pressure LOCAs during hot shutdown operation (4h after reactor trip) Initial conditions with core power at 0.92%FP, intermediate primary pressure LOCAs during full power operation Initial conditions with core power at 100%FP, high primary pressure This talk focuses on effect of safety injection time, injection rate and steam generator reflux condensation on core recovery MELCOR nodalization for 2-loop Westinghouse PWR Loss of RHR during mid-loop operation Objective Determine latest injection time to recover the core without damage Assumptions Upper head in place and bolts detensioned No accumulator available One injection pump available for recovery with limited flow rate (3.5kg/s for base case, 3.0kg/s for sensitivity study) delayed some time after core uncovery (2840s for the reference case, 2640s and 3040s for sensitivity studies) Comparison of event sequences Comparison of core liquid levels Comparison of maximum fuel rod temperatures Loss of RHR during mid-loop operation Summary Core can be recovered with just 3.5 kg/s injected (one charging pump) before oxidation excursion Insensitive to injection rate as low as 3.0kg/s Injection can be delayed until core is about 50% uncovered corresponds to max. core temperature of about 1000 K in reference case high likelihood of oxidation excursion if injection is