21. Use of Risk Analysis During the Operations Phase

Quantitative risk analysis was for a long time used mainly for the design phase and for extensive modifications. If the analysis was carried out in the operations phase, it was conducted in a way corresponding to use in the design phase, without reflecting the vast differences between design and operation from a HES (or strictly speaking major hazard risk) management point of view. The use of QRA in the operations phase has increased in the last ten to fifteen years. It is now conducted in different ways, in order to reflect the important differences from a management point of view. Several aspects in this connection are discussed in this chapter including updating of QRA studies, operational improvements, barrier improvements, and analysis of maintenance and modifications. The main use of risk evaluations in the operations phase is for qualitative evaluations, as review and work preparation tools. This is also briefly considered.