Results from our experiments on dissolution rates o! 23S Pu0 2 and 239 PuO2 in distilled water and normal saline solution were compared with rates calculated from data in the literature on various PuOj dissolution experiments.The initial comparatively rapid dissolution rates were found to vary widely, even between experiments performed ostensibly under the same conditions. In contrast, the lower rale of dissolution, which, began a few hours after contact of the oxide with the aqueous medium, was found to be constant and fell within a rang* of 1 to 6 ng/m^s under widely varying conditions.

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A 238 Pu fueled sphere assembly (FSA) was exposed to a simulated humid environment on sandy soil for 3 yr. After a 70-wk exposure, plutonium was first detected in measurable quantities in rain and condensate samples. A core sample taken in the 93rd wk contained 302 ng of plutonium. Examination of the FSA after exposure revealed a hole in the bottom of the graphite impact shell (GIS) and a leaking weld on the vent assembly of the postimpact containment shell (PICS). These two openings may be the pathways for plutonium entry into the environment from the FSA.

No abstract