Lessons learned from NU plant specific PRA program

Northeast Utilities (NU) has embarked on a program to develop, maintain, and utilize living Probabilistic Risk Assessments (PRAs) for plant support on all of its nuclear power plants. Corporate commitment to this program originates from the success in identifying problem areas from limited scope PRAs performed in the late seventies by NU. These limited successes lead to the development of a fully self-sufficient, state-of-the-art in-house capability, to the establishment of a quantitative corporate safety goal, and to the establishment of a corporate program for maintaining and utilizing plant specific PRAs in all facets of plant support activities. The NU PRA program has clearly shown that PRA works, both as an internal, decision making tool, and as a safety analysis tool for dealing with the regulatory authorities. PRA has identified real oppotunities for reducing risk at power plants. Because of this, PRA is being established as a powerful, credible system engineering tool within our engineering support organization. PRAs are providing strong bases for understanding where resources should be directed to improve plant safety. This understanding of, and control over the backfit program is critical because, even if backfits are mandated by the NRC, the authors remain responsible for the safety consequences of these backfits