SPENT ALUMIUM PLATED FUEL STORAGE SYSTEM AT THE IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY - TECHNOLOGIES AND EXPERIENCE

摘要

Spent aluminum plated reactor fuels have been stored at the Idaho Nuclear Technology and Engineering Center (INTEC) fuel storage facility (INTEC-666) on the Idaho National Engineering and Environmental Laboratory (INEEL) since 1984. INTEC-666 is a wet fuel storage facility with six storage pools, two cask-unloading pools, two isolation pools, and a transfer channel. All of these pools and channel are stainless steel lined. The total water volume is 1.23 × 10{sup}7 liters. Pool water is circulated continuously from all six storage pools through: 1) stainless steel filters, 2) stainless steel, ion exchange trains, 3) coolers (chiller and heat exchanger), and 4) an ultraviolet (UV) sterilizer. This water treatment system provides parallel filters, cooling units, and ion exchange trains that are two beds in series. In practice a filter is in series with an ion exchange train. The water is returned to the cask unloading pools and flows through the transfer channel into the storage pools. A makeup system is also present to add water that is lost by evaporation from the open pools and channel. The water treatment system was designed to control the water quality to specified limits to maintain pool liner, fuel cladding, and fuel rack integrity during the storage period of the spent fuel. The integrity of the liner, cladding, and fuel racks is affected by corrosion. Corrosion can not be avoided but the rate of corrosion may be minimized. The controls that are used at the INTEC are low pool water ion concentration (specifically chloride) and pool water temperature for reduced bacteria and algae growth. The reduction of the pool water ion concentration is by ion exchange. Maintaining the pool water temperature within a certain temperature range minimizes the bacteria and algae growth. Warm and cold water temperatures encourage bacteria and algae growth. The coolers control the temperature by removing the heat that is generated primarily by the radioactive decay of the spent fuel elements and by maintaining pool water temperature in a required range. The handling of the spent fuel rods requires pool water clarity that is controlled by the removal of suspended solids, and suspended bacteria and algae. These suspended particles are removed in the filter units. The UV sterilizer unit destroys suspended bacteria and algae. Coupons that are placed in various locations within the pools monitor the corrosion rate by an annual checking to determine the amount of corrosion. The effects of stored fuels at INTEC-666 and the performance of the treatment system are reported. The conclusions provide the basis for the facility operation and equipment.