CONSIDERATIONS FOR TRANSPORTATION LICENSING OF USED FUEL ALREADY IN INTERIM DRY STORAGE

Currently in the United States of America (USA) used fuel assemblies from commercial nuclear power plants are in interim dry storage at various sites. The typical interim dry storage systems used for these assemblies are either storage casks or canisters stored in storage overpacks. Some of these systems were licensed and have had fuel assemblies in dry storage for a period of more than 20 years. The majority of the systems used for storage are also designed to comply with transportation regulations. However, some of the earlier vintage interim dry storage systems were not designed to be compliant with the requirements of transportation. It is desirable from a safety and economics point of view that these storage systems also be qualified for transportation. This qualification for transportation would eliminate the need to remove and repackage used fuel from these storage containers prior to eventual transportation. The transportation regulations have several requirements that are different than those for storage. Additionally, transportation regulations have evolved over the time period that the used fuel has been in storage. Design analysis methods and computer codes have undergone significant changes over time. The current accepted practices and regulatory expectations have also evolved and are different than they were when these systems were designed and licensed. Therefore, if a user of these interim dry storage systems desires to have them qualified to meet current transportation regulations, evaluations are required to demonstrate that these systems are compliant with current transportation requirements and regulations. This paper examines some of the challenges that a user might encounter during these evaluations. The differences in design and analysis methods including computer codes are discussed. Fabrication, testing and inspections requirements during fabrication, loading, operation and maintenance are examined to evaluate the suitability of these interim dry storage systems for transportation. The impacts on the already designed, fabricated and storage licensed containers due to changes in the current practices and regulatory expectations are presented.