"EXTENDING A HCLPF-BASED SEISMIC MARGIN REVIEW TO ANALYZE PLANT DAMAGE STATES AND THE ROLE OF HUMAN FACTORS AND NON-SEISMIC FAILURES"

TECHNIQUES HAVE RECENTLY BEEN DEVELOPED TO ANALYZE THE 'SEISMIC MARGIN' OF A NUCLEAR POWER PLANT USING THE HCLPF CONCEPT (HIGH CONFIDENCE OF A LOW PROBABILITY OF FAILURE). STARTING WITH AN EARTHQUAKE LEVEL SHOSEN FOR MARGIN REVIEW, THE TECHNIQUE DETERMINES WHETHER THE PLANT CAN OR CANNOT 'WITHSTAND THE REVIEW-EARTHQUAKE WITHOUT CORE DAMAGE. HERE 'WITHSTAND' MEANS 'WITHSTAND WITH A HIGH CONFIDENCE OF LOW PROBABILITY OF FAILURE'. THIS HCLPF-BASED METHOD CAN SCREEN A PLANT'S SEISMIC 'MARGIN' WITHOUT UNDERSTAKING A FULL-SCOPE SEISMIC PRA. HOWEVER, THE INSIGNTS FROM THE METHOD ARE LIMITED,PARTLY BECAUSE THOSE ACCIDENT SEQUENCES THAT DOMINATE THE HCLPF-BASED ANALYSIS ARE NOT THEMSELVES ANALYZED FURTHER. IN THIS PROPOSED PROJECT, THE FEASIBILITY OF CARRYING THE HCLPF-BASED ANALYSIS ONE STEP FURTHER WILL BE EXPLORED. IF THIS 'ONE STEP FURTHER' IS FEASIBLE, EACH KEY SEISMIC ACCIDENT SEQUENCE COULD BE ASSIGNED A PLANT DAMAGE STATE (CONTAINING INFORMATION ABOUT OFFSITE RELEASE MAGNITUDE, TIMING, AND PROBABILITY) AND THE ROLE OF HUMAN FACTORS AND OF NON-SEISMIC-INDUCED FAILURES COULD BE BETTER UNDERSTOOD, WITHOUT THE NEED OR EXPENSE OF A FULL-SCOPE SEISMIC PRA.