Safety engineering can be defined as the study of the causes and the prevention of accidental deaths and injuries. The field of safety engineering has developed within several disciplines, and its practitioners have operated under a wide variety of position titles, job descriptions, responsibilities, and reporting levels. Safety engineering includes the identification and appraisal of accident-producing conditions and practices, and the evaluation of the severity of the accident problem. This is done by the development of accident and loss-control methods, procedures, and programs (partly adapted from (EBO, 2008)).
Safety engineering is under constant development and new methods are being developed. In recent years, several scientists have stressed the need for a different approach within safety engineering that includes studying normal performance rather than failure. This has become known as resilience engineering. In the same period, several research projects have worked to develop traditional risk assessments. This involves risk analysis as well as an evaluation of the results. Probabilistic safety assessment (PSA) is one of the terms used for a type of risk assessment. It is also referred to as quantitative risk assessment (QRA), probabilistic risk assessment (PRA), concept safety evaluation (CSE), and total risk analysis (TRA). Despite more than two decades of use and development, no convergence towards a universally accepted term has been seen (Vinnem, 2007). In this article, the term PSA refers to all the different techniques.