DISSOLUTION OF IRRADIATED CONSOLIDATED EDISON POWER-REACTOR FUEL BY THE SULFEX AND DAREX PROCESSES

Losses of fertile and fissile materials during chemical decladding of irradiated prototype Consolidated Edison power-reactor fuel pins by the Sulfex and Darex processes were determined, on a laboratory scale, in all-glass apparatus. For air-fired low-density (-85 per cent of theoretical) fuel cores, minimum losses of uranium, thorium, and plutonium were in the 0.1 to 0.2 per cent range, by either process. These losses increased if the dejacketed cores were allowed to remain in contact with the cladding solution. No selectivity of dissolution of core components was apparent. Comparable losses were obtained with similar unirradiated fuel pins, irradiated core pellets showed a tendency to shatter. When shattered core pellets were present, losses to the cladding solution were excessive. Losses of from 0.5 to 4.5 per cent were observed, depending on the extent of core fragmentation and the time of contact with the cladding solution. No correlation between burnup and extent of shattering was discernible. Core dissolution times were not lengthened by irradiation to the 175 to 300-Mwd/t core level. (auth