Results of tracer studies suggest that, in tributyl phosphate extraction processes designed to recover and purify fissionable material, minimum ruthenium extraction should be obtained from feeds at least 2 M in nitric acid or at least 1 M acid-deficient. Ruthenium decontamination was decreased by preheating the feed and increased by pretreatment with reducing agents. A pretreatment using 0.06 M ferrous ion and 0.5 M urea with 1 hr simmering at 85°C should increase ruthenium decontamination about 10-fold in the 25 process. If other process considerations dictate the use of a low-acid feed, decontamination from ruthenium may be improved by using 3 M nitric acid as the scrubbing solution. Apparently, the scrubbing process is quite time-dependent; a solvent holdup time of about 15 min may be needed in the scrub section for maximum decontamination.

Results of processing 47 metric tons of Brookhaven spent reactor fuel are summarized.