Human factors and risks in a periodic safety review of a nuclear power plant

This paper describes human factors assessments recommended as a part of periodic safety reviews of nuclear power plants. The contents, source material and the report structure are described. This approach has been used in the operating license renewal application of a specific nuclear power station and submitted to safety authorities. The qualitative part of the human factors review is structured according to IAEA Safety Guide No. NS-G-2.10. The qualitative descriptions are enhanced with statistical data obtained from inspections and assessments made by plant quality assurance (QA) personnel, by regulatory authorities and by peer reviews. The quantitative assessment is based on the roles and contributions of human errors in the accident risk at the plant. The assessment uses importance measures quantified in probabilistic safety assessments (PSA). It considers also the scope and quality of PSA and human reliability assessment, and how PSA is used to reduce errors and improve human factors. The results are quite plan-specific and errors have very different importances in different operating states and for different initiator categories. The results are useful for preventing errors by developing and prioritizing human factors improvement activities.