Establishing of a Monitoring Process to Support Long-running Package Approvals of Dual Purpose Casks

According to the German Atomic Energy Act, the safe storage of the irradiated nuclear fuel in transport and storage casks inside interim storage facilities has to be guaranteed until their handover to a final repository. By the use of Dual Purpose Casks (DPC) placed in dedicated on-site and, in the past, central storage buildings this legal requirement is implemented by the operators of the nuclear power plants. The licensing of such installations comprises the licensing of the storage of the irradiated nuclear fuel itself in casks, but requires additionally a package design approval for these transport and storage casks to demonstrate the compliance with the transport regulations.Traditionally, the validity period of a storage license, normally 40-50 years for the whole legally allowed interim storage period, differs significantly from the validity period of a package design approval, which is limited to 5 years in the international practice. In order to harmonize the legal status of the DPC, the extension of the package approval validity until the end of the storage period including the subsequent transport after storage to a final repository would be favorable.Some time ago and based on the initiative of GNS the discussion was started in Germany to develop rules and requirements as a first basis for an extended validity period of the package design approvals. Rules and requirements have been detailed and improved further and constitute today a coherent framework for a validity period of German package design approvals for DPC which can be extended to the validity of the storage license. Measures to be performed by the applicant like evaluation of the operation experience during storage, consideration of physical and chemical aging effects for the safety relevant boundary conditions of the safety case as well as for the inspection program to be applied before transport after storage as well as the assessment of aging of the legal, regulatory and design methodology bases are established as first of its kind.The authors describe their experience concerning the implementation of the measures and the effectiveness of a monitoring process according to the transport regulations.