LEARNING BY ACCIDENT - REDUCTIONS IN THE RISK OF UNPLANNED OUTAGES INUS NUCLEAR-POWER-PLANTS AFTER THREE-MILE-ISLAND

This study uses a Cox proportional hazards model to analyze changes in the risk of unplanned outages in U.S. nuclear power plants after the Three Mile Island (TMI) accident. The unplanned outage hazard is relat ed to safety by the fact that most such outages begin with unplanned r eactor scrams. These place extreme stresses on plant equipment, increa sing the risk of serious accident. The estimates indicate that the Nuc lear Regulatory Commission (NRC)-led efforts to improve nuclear plant safety after TMI were followed by substantial reductions in the risk o f unplanned outages.