PROCEDURE FOR THE ANALYSIS OF ERRORS OF COMMISSION DURING NON-POWER MODES OF NUCLEAR-POWER-PLANT OPERATION

The continued, historical occurrence of human interactions which place nuclear power plants in a condition of potentially heightened risk is of increasing interest to regulators, utility management, and industr y observers alike. These Errors of Commission (EOCs), as they are ofte n called, lead to a variety of questions such as: 'Can the event lead to a potentially dangerous condition such as core damage? By what fail ure mechanisms? With what frequency? What defences does the plant have to mitigate the event? Are these actions in the Probabilistic Risk As sessment (PRA) model of the plant?'. EOCs are often excluded from the bounds of a typical PRA model, yet they have the potential for being s ignificant contributors to risk. This paper is the second of two descr ibing procedures for the analysis of the potential for significant err ors of commission. The first paper addressed operations at power while this paper describes the procedure for non-power operations. Each pro cedure describes a method for identifying the opportunities for error, identifying failures modes of functions, systems, or components that could arise from such errors (referred to in this paper as error expre ssions), and the identification of the most significant of these EOCs based on consideration of consequences, recovery potential, and likeli hood. (C) 1996 Elsevier Science Limited.