PACKAGE APPROVAL FOR TYPE DUAL PURPOSE CASK PACKAGES

In Germany, the Atomic Energy Act regulates the disposal of spent fuel in a way that it has to be disposed of as radioactive waste in a controlled manner (direct disposal). For this purpose, proof must be given that the safe storage in interim storage facilities is guaranteed until the radioactive waste is delivered to a facility for final disposal. The German guideline for the dry interim storage advises to use massive metallic casks, for example made from monolithic cast iron with a double lid system. At the beginning of the storage period, the storage casks have also to be approved as transport package according to the transport regulations. The transportability has to be demonstrated, e.g. by maintaining the package approval over the entire storage period or otherwise. The legal requirements can be fulfilled by the use of so-called Dual Purpose Casks (DPC), casks able to be used for transport and storage of the radioactive waste. In Germany, the licensing of such casks has to be undertaken for transport and storage separately. As a result, the validity of the package approval is limited to 5 years; however, the storage license is valid over the whole storage period, e.g. 40 years. In order to harmonise the legal status of the DPC, the prolongation of the package approval validity until the end of the storage period plus the transport away from the storage would be favourable. From the technical point of view, this could be achieved by evaluating and assessing the storage conditions with impact on the package performance under transport conditions also within the package approval procedure. Additionally, measures would have to be established to check the compliance of the loaded casks in relation to the approved design over the storage period. The measures would concern the operating experience related to the quality assurance program, ageing aspects related to safety related frame work as well as the inspection program prior to the off-site-transport. The authors describe the German situation, the discrepancies between transport and storage regulations and present approaches for solutions.