EVALUATION OF ULTIMATE DISPOSAL METHODS FOR LIQUID AND SOLID RADIOACTIVE WASTES. V. EFFECTS OF FISSION PRODUCT REMOVAL ON COSTS OF WASTE MANAGEMENT

In a study based on optimistic expectations of waste composition from future fission product separations processes, estimated costs for management of wastes from which 90 and 99% of all fission products were removed were from 70 to 80% of those for management of waste from which no fission products were removed. This cost difference is not believed to be sufficient to pay for the separation and final disposal of the fission products, which was not included in the waste management costs; hence, separation does not represent an economic route for waste management unless a substantial market for the fission products exists to pay most of the costs. As a basis for this study, it was assumed that after fission product removal the waste was identical to neutralized Purex waste in volume and composition of major ingredients. The sequential steps in the management of waste from processing 1500 metric tons per year of uranium converter fuel irradiated to 10,000 Mwd/ton were: interim storage of liquid waste, conversion to solids by pot calcination, interim storage of calcined solid waste, shipment of 1000 miles, and final disposal in a salt mine. Minimum-cost schemes were worked out involving optimum choices of interim liquid and solid storage times, diameter of the waste-calcination cylinder, and age at time of burial in the sa1t. Costs for wastes from which fission products were removed were 1east for calcination in 24-in.-dia. vessels, were not strongly affected by age, and fell in the range of 0.017 to 0.019 mill/kwh(e). The lowest cost for acid Purex waste without fission product removal was about 0.024 mill/kwh(e), obtained by using either 12- or 24-in.-dia. calcination vessels and buried in salt after allowing 30 years for decay of the fission products in the calcined wastes. These costs are equivalent to about 00 per ton of fuel for acidic Purex, and about 00 to P1200 per ton for the depleted wastes. (auth