ANALYSIS OF SPENT FUEL FROM LIGHT WATER REACTORS

A detailed knowledge of the LWR inventoryimposed constraints on the heavy metal handling capability for the transport, storage, and disposal components of the overall waste system has been developed as part of a GA Technologies evaluation of a universal waste canister concept. A time-phased burnup and age distributions of the inventory through 2020 has been converted to time-phased inventory distributions for heat load, gamma, and neutron shielding sources through the use of relatively simple, but sufficiently accurate, equations. The inventory analysis has also included the initial fissile enrichment distribution studies and oriticality analysis to assess the criticality constraints imposed by the inventory characteristics. Using the draft repository reference schedule from the April 1984 Draft Mission Plan, the inventory analysis indicates that a high capability system requires a shielding and heat load design basis equivalent to that required for 40,000 MWd/MTU and 7 years cooling with a capability for handling unburned fissile enrichments up to 3-75? U-235. If the 1984 Draft Mission Plan schedule is considered the reference schedule, systems based on the current design basis of 33,000 MWd/MTU and 10 years cooling will be inventory limited to typically 50$ to 60? of the total inventory with reference burnup assumptions or as low as about 25? of the inventory if extended burnup fuel designs are introduced resulting in -40? increase in average burnup over current levels.