Abstract: A method of predictably dewatering a slurry that contains radioactive particles to a condition for safe permanent storage. Interstitial water is removed from the slurry, and then a sufficient quantity of adsorbed water is removed from the particles so that at the permanent storage temperature the particles will be just unsaturated with respect to adsorbed water. The dewatering endpoint is set to at least unsaturate the particles at the permanent storage temperature. This minimum volume of adsorbed water removal is necessary to assure the subsequent uptake of any condensed water that develops during storage in a sealed container. An upper dewatering endpoint is preferably set so that the volume of adsorbed water removed from the particles does not excessively unsaturate the particles, so that the sealed storage container that eventually confines the dewatered particles will not burst if the particles later become exposed to ambient water or water vapor.

Abstract: A storage system for storing spent nuclear fuel on site at a reactor complex includes a concrete storage cask adapted to receive fuel assemblies or loaded fuel canisters from the spent-fuel pool. The storage cask is sealed and maintained on site for a predetermined time period. The fuel assemblies or canisters can then be transferred from the concrete storage cask to a shipping container for shipment to a permanent disposal site, while the concrete casks can be reused or broken up so that the concrete can be used as fill or ballast. The fuel assemblies or canisters are removed from the pool and placed in the cask in a dry condition. Alternatively, the cask may be submerged in the fuel pool for loading. Preferably, the cask is sealed and backfilled with an inert gas. In one embodiment of the invention, the concrete storage cask is manufactured on site at the reactor complex.

Abstract: Disclosed is a method of installing a reversibly porous, air-diffusible, water-restrictive, polymer plug in a port that extends through the wall of a nuclear waste storage container. The plug is inserted a predetermined distance, for example, with the aid of a screwdriver applied to a slot in the plug's outer face. When inserted, the plug prevents the loss of nuclear waste through the port while the air-diffusible nature of the material allows gases to pass through the material. The resultant venting action of the plug prevents the creation of pressure differences between the interior of the container and the environment. Thus, the likelihood of the container becoming overpressurized and leaking is minimized. In addition, the water-restrictive nature of the plug material restricts the ingress and egress of water from the container, reducing the likelihood of groundwater contamination during storage.