Switzerland's regulatory approach to manufacturing and use of dual purpose casks for transport and storage of vitrified high level waste and spent nuclear fuel

After the political decision to stop reprocessing of spent fuel (SF) by mid-2006, the availability of dual purpose casks (DPCs) became as vital for the SF-management of Swiss nuclear power plants as they already were for the repatriation of reprocessing waste from France and the United Kingdom. Soon the Swiss regulatory authority (ENSI) received several applications of transport and storage casks designs for use in the interim storage facilities. The guideline ENSI-G05 specifies the detailed requirements for the interim storage casks based on general requirements in the nuclear energy act and ordinance. Today 12 different casks designs have either been approved by ENSI or are in the approval process. ENSIs transport group has developed a dedicated management process to deal with the specific aspects of such applications: the close relationship between transport and storage requirements which however show important differences in detail resulting in two separate safety files, one of them reflecting the transport configuration and international ADR requirements and the other one reflecting the storage configuration and national storage requirements. Following the design approval with respect to transport and storage requirements ENSI carries out a product specific manufacturing control for each single DPC. Whilst design approval is largely based on the manpower of permanent staff, manufacturing control is generally sub-contracted to independent external expert organizations. However, according to regulatory guide ENSI G05 the primary responsibility for the quality of the produced DPCs is with the cask owner i.e. the customer of the manufacturer. Together with the manufacturer, the owner has to carry out the most detailed manufacturing control program the results of which have to be submitted to ENSI and the in-dependent expert. The regulatory guide ENSI G05 defines in detail the responsibilities and duties of involved parties in the framework of storage cask manufacturing. In the last IRRS-mission it was recommended that ENSI should publish a corresponding document covering these issues in the framework of transport regulations. According to Swiss regulation the various responsibilities for class 7 dangerous goods transport in Switzerland is shared amongst 3 authorities which have issued a joint guidance document covering design construction and operation/use of qualified packages starting from IP- up to B(U)F-classification. Both documents also cover the operational lifetime of packages in addressing issues such as operational records, updating of the safety documentation, periodic maintenance and testing, repairs and ageing management programs. (author)