Insights from a Full Scope Level 2 PSA Model for a PWR Plant With Spherical Shell Containment

A full scope Level 2 PSA was performed in 2005 for a three-loop PWR plant with spherical shell containment. New regulatory definition of large early release, and new reporting requirement related to large late release drive the technical approach in this study. New plant features, new accident management guidelines, and new thermal hydraulics and source terms calculations were incorporated in the linked Level 1 and Level 2 model. The plant features observed to be important for accident mitigation include: 1) primary depressurization; 2) accident induced hot leg failure; 3) hydrogen burn mitigation; and 4) containment filtered venting.