Crucial role of detailed function, task, timeline, link and human vulnerability analyses in HRA

The authors address a major cause of large uncertainties in human reliability analysis (HRA) results. They examine the potential contributions which detailed analyses can make in achieving quantitative and qualitative HRA results which are creditable, i.e. minimally uncertain; auditable, i.e. capable of systematically linking quantitative results and qualitative information from which the results are derived; capable of supporting root cause analyses on human reliability factors ascertained to be major contributors to risk; and capable of repeated measures and combination with similar results from other analyses to examine HRA issues transcending individual systems and facilities. Based on experience analyzing test and commercial nuclear reactors, and medical applications of nuclear technology, an iterative process is suggested for doing detailed function, task, timeline, link, and human vulnerability analyses using documentation reviews, open-ended and structured interviews, direct observations, and group techniques