ASSESSMENT OF HUMAN RELIABILITY-BASED ON EVALUATION OF PLANT-EXPERIENCE - REQUIREMENTS AND IMPLEMENTATION

A major problem in assessment of human failures in probabilistic safet y assessment is the lack of empirical data needed for human reliabilit y analysis (HRA). This problem is aggravated by the fact that differen t HRA methods use different parameters for the assessment and that MA is currently enforced to provide data and methods for assessment of hu man reliability in new technical environments such as computerized con trol rooms, in accident management situations, or in low-power and shu t down situations. Plant experience is one source to deal with this pr oblem. In this paper, a method is presented that describes how plant e xperience about human failures and human performance may be used to su pport the process of analyzing and assessing human reliability. Based on considerations of requirements of HRA, a method is presented first which is able to describe and analyze human interactions that were obs erved within events. Implementation of the approach as a database appl ication is outlined. Second, the main results of the application of th e method to 165 boiling water reactor events are presented. Observed i nfluencing factors on human performance are discussed; estimates fur p robabilities are calculated and compared with the data tables of the T HERP handbook. An outline is given for using the presented method for the analysis of cognitive errors or organizational aspects. (C) 1998 E lsevier Science Ltd.