Year
1989
Abstract
The development of interim storage techniques makes it possible to store spent fuel safely and economically for long periods. The need for sufficient storage capacity can be met by use of compact storage racks, rod consolidation, wet storage or dry storage concepts. Wet storage used worldwide is not the most economical solution. Therefore, alternative storage concepts involving dry storage were investigated. Many different types of dry storage systems have been developed, particularly casks, drywells and vaults. Vault storage involves a concrete bay, where the fuel is stored in sealed canisters or in baskets. In \"closed-cycle\" vaults, the primary cool anl~~gas~~is~ ~recTrcu la ted and transmits its heat to an air-heat exchanger; others operate in an oncethrough mode. The at-reactor dry storage facility developed by Siemens receives spent fuel assemblies in dry shipping casks, which are transported by means of a trailer into the receiving area for subsequent mating with the unloading cell gate. The spent fuel assemblies are unloaded, canned in steel canisters to provide the physical barrier to prevent the release of radioactive particulate and transferred to the storage location. The canisters are stacked in a horizontal orientation, one above another. Subcriticality is ensured by the chosen pitch and shielding from radiation is ensured by the design of the building. The heat removal system consists of direct air-cooling by natural convection.