Dry Storage Ageing Project for Dual Purpose Casks in Switzerland

For several years, many activities have been launched concerning ageing issues of dry storage casks for spent fuel as, for example, the joint working group of the transport and waste safety committees of the IAEA, TRANSSC and WASSC. As a result, TRANSSC intends to introduce ageing requirements in the upcoming revision of the transport regulations.At the national level, several ENSI guidelines include ageing requirements based on different regulatory concepts. Specific ageing issues are already identified by the utilities and carried on to research projects. The announced prolongation of the final repository project in Switzerland gives an additional reason to deal with long time storage periods and ageing issues of dry storage casks.As a result of these activities ENSI has identified the need for a comprehensive reassessment of the dry storage ageing issue resulting in a regulatory research project. The purpose of the project is to introduce a holistic approach covering all relevant technical ageing aspects and to identify necessary enhancements of Swiss regulatory framework and the need for additional research work.The paper provides information concerning the initiation and the background of the project. This is followed by a brief description of the conduct of the work and the subjects addressed in particular within the project. More attention is spent on the results of the project: Further actions are identified in the fields of package components, spent fuel properties and final disposal procedures. The general aspects additionally identified in the project will be also discussed. The paper concludes with the summary of results, a description of the overall ageing management concept proposed by the project team for implementation and the path forward concerning ageing issues in Switzerland.