2015:04 DiD-PSA: Development of a Framework for Evaluation of the Defence-in-Depth with PSA

The project declares an interpretation of the definitions of Defence in Depth given by IAEA which outline a framework to meet PSA. For each level of defence and combinations of levels, methods to give estimates from a PSA perspective are presented and discussed. One important result is the discussion of the basic definitions and the basis for defence-in-depth, as defined by IAEA, leading to somewhat modified and further developed definitions that support the link to a developed PSA.

This report clarifies the links between the defence in depth, as defined by IAEA and SSM code of statutes, and link to possible PSA measurements (input data or results from quantifications). This basis can be used in a development of event reporting, the adaptation of PSA models in support of more complete DiD levels evaluation, and development of result presentation supporting insights into plant DiD strengths and weaknesses. Such development contributes to SSMs and the utilities evaluation of the existing DiD, the importance of events in relation to the DiD and the DiD impact from plant changes.