Power reactor events and issues

This publication reviews selected operating events that have occurred at nuclear power plants and presents the results of NRC-sponsored analysis of pertinent operating issues. This study was initiated following several instances of water hammer involving the service water system at Arkansas Nuclear One. The task was to evaluate the need to reissue previous NRC guidance about water hammer or to suggest additional measures to prevent or mitigate their occurrence. Twelve from PWR and BWR type reactors were studied. This study concluded that the frequency of reported water hammer occurrences continues to drop and no new phenomena were identified as causes of water hammer. In addition, this study supports prior NRC conclusions regarding water hammer; however, some aspects that could impact safety and were identified in this study had not been previously emphasized