B245 Technical Issues for Safety Improvement 4 : Integrity of Containment

This paper summarizes current status of knowledge and technical issues for safety enhancement by severe accident management for ex-vessel melt coolability and containment cooling. Since melt coolability still has a large uncertainty, confirmation of effectiveness of early coolant injection (or advance flooding) may contribute higher confidence level to arrest molten core concrete interaction. For new reactor design, material property is the key information for core catcher configuration to cool the melt effectively. Containment cooling by steam condensation utilizing existing cooler or dedicated passive system can suppress overpressure/temperature and minimize radioactive release to the environment. System interaction test with non-condensable gas plays important role in case of passive system. Analytical model enhancements and their verification are necessary, as well as their integration as a system model.