Review of the SKB SR-Can interim report: Evaluation by the Nuclear Inspectorate and the Radiation Protection Authority of SKB's updated methods for safety analysis

In this report the Nuclear Inspectorate and the Radiation Protection Authority comments on the present stage of the safety analysis for an encapsulation plant for spent nuclear fuels and a underground repository. According to the evaluation of the authorities, the SKB methods for safety analysis are well structured and logical and have good potentials as starting points for future safety analyses. However, important parts of the methods need further developments before they can be used for licensing applications. Important progress has been made in several areas compared to the latest safety analysis, SR97, for instance regarding the method for systematic identification and description of all the processes and conditions that need to be considered in the analysis. SKB has also produced improved methods for documentation of different types of expert evaluations and for selection of data for model calculations. Like the international group of experts we see shortcomings in the SKB method for identification and selection of scenarios. The authorities believe that SKB should show, in a systematic and traceable way, that all unfavourable processes, conditions et cetera that have been identified, and could be of importance for the scenario, have been thoroughly evaluated. The authorities see weaknesses in the quality assurance of the interimistic report, that complicates the evaluation of the methods for safety analysis. There are also ambiguities in how SKB plan to optimize/select the best technologies and the role of the safety analysis in this connection. Finally, the authorities give recommendation on how SKB should present the model and methods for analysis that are not yet developed