Precursors to potential severe core-damage accidents: 1969-1979 a status report

One hundred and sixty-nine PWR and BWR events for the years 1969 through 1979 were selected as precursors to potential severe core damage, based on the selection methods and criteria described in Vol. 1 of this report. These precursors are documented herein. For each precursor, four items are included: a precursor description and data sheet lists the report date, briefly describes the LER event, identifies what corrective action was taken after the event, describes the purpose of the failed system or component, and lists the unavailability of equivalent systems and components as determined in the Reactor Safety Study; an actual-occurrence event tree describes the major functions associated with the reported event which maintained the plant in a safe condition; a sequence-of-interest event tree describes safety-related functions required to prevent severe core damage for a postulated initiating event; and a categorization of accident sequence precursors sheet lists characteristics identified for each precursor