Study on default setting for risk-informed regulation

Both performing and validating a detailed risk analysis of a complex system are costly and time-consuming undertakings. With the increased use of probabilistic safety analysis (PSA) in regulatory decision making, both regulated parties and regulators have generally favored the use of defaults, because they can greatly facilitate the process of performing a PSA in the first place as well as the process of reviewing and verifying the PSA. The use of defaults may also ensure more uniform standards of PSA quality. However, regulatory agencies differ in their approaches to the use of default values, and the implications of these differences are not yet well understood. Moreover, large heterogeneity among licensees makes it difficult to set suitable defaults. This study focus on the development of model for setting defaults in order to achieve more applicability of risk-informed regulation. In particular, explored are the effects of different levels of conservatism in setting defaults, and their implications for the crafting of regularity incentives. (author). 17 refs., 1 tab