SPECIAL SAFETY REVIEWS FOLLOWING ACCIDENTS AND MAJOR INCIDENTS AT NUCLEAR POWER PLANTS

摘要

An overview is given in broad terms of major safety reviews and other actions taken on the basis of lessons learned from the two most severe accidents in commercial nuclear power plants that have occurred so far, namely at Three Mile Island in 1979 and at Chernobyl in 1986. To prevent such accidents from happening in the future, it is mandatory to identify and act upon any warning signals for safety deficiencies, as the lessons learned from these two accidents show. Examples of such warning signals-both from actual incidents and from improved analytical assessments-are given. As the basic goal for nuclear safety work must be to have no severe accidents in the future, it is concluded that continuous learning from the operating experience is most important, including early identification of trends, indicating deteriorating performance of systems or organizations, and identification of precursor events which give warning signals for potential weaknesses in critical safety functions. Moreover, it is vital to perform systematic reassessment of the safety cases of nuclear power plants designed to earlier standards, using modern assessment methods and supporting data.