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30 Years of Safety Assessment at Sellafield

Abstract The Sellafield site comprises a range of nuclear reprocessing and waste treatment facilities, both operational and redundant. Even 30 years ago, detailed safety assessment of new facilities was being carried out. Over the decades, detailed safety assessment of existing facilities has been introduced, along with a ten-year review cycle. The challenge for safety assessment posed by some facilities moving from operation to decommissioning is explored. The development of safety assessment methods over the last 30 years is described, including the roles of HAZOP probabilistic safety assessment, design basis accident analysis, engineering substantiation, safety-designation of important equipment and procedures, and application of the ALARP principle.