The methods that are used today in PSA are applicable for evaluating defence-in-depth levels 1 and 2. Failure data can be determined through: human reliability analysis, riskinformed in-service-inspection methodology, system reliability analysis and directly from plant specific failure data for the components. Many DID activities against LOCA are not explicitly modelled in typical PSA-studies. DID activities and systems identified in this study can play a role in several DID levels, and the evaluation of the DID level must therefore be judged by the initiating event.
