Learning by accident? Reductions in the risk of unplanned outages in U.S. nuclear power plants after Three Mile Island

Abstract

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 related to safety by the fact that most such outages begin with unplanned reactor scrams. These place extreme stresses on plant equipment, increasing the risk of serious accident. The estimates indicate that the Nuclear Regulatory Commission (NRC)-led efforts to improve nuclear plant safety after TMI were followed by substantial reductions in the risk of unplanned outages.