A procedure for the analysis of errors of commission in a Probabilistic Safety Assessment of a nuclear power plant at full power

This paper describes an analytical procedure that has been developed to facilitate the identification of errors of commission for inclusion in a Probabilistic Safety Assessment (PSA) of a nuclear power plant operating at full power. The procedure first identifies the opportunities for error by determining when operators are required to intervene to bring the plant to a safe condition following a transient, and then identifying under what conditions this is likely to occur using a model of the causes of error. In order to make the analysis practicable, a successive screening approach is used to identify those errors with the highest potential of occurrence. The procedure has been applied as part of a PSA study, and the results of that application are summarized. For the particular plant to which the procedure was applied, the conclusion was that, because of the nature of the procedures, the high degree of redundancy in the instrumentation, the operating practices, and the control board layouts, the potential for significant errors of commission is low.