The Los Alamos Scientific Laboratory contribution to the Waste Isolation Safety Assessment Program, Task 4, for the second quarter of FY-79 involved plutonium, americium, and uranium(VI) batch sorption studies on argil!ite. The behavior of plutonium and americium in aqueous solutions at pH * 8 with respect to container sorption, filtering, and centrifuging was also investigated. Studies of the variability of the sorption behavior for tuff were completed. Migration rate studies on crushed and

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... ctured materials were initiated,. The development of the systems for performing controlled atmosphere measurements has been completed. Additional chemical analysis have been performed s as were some studies related to microautoradiography. Additional cation exchange capacity and ethylene glycol surface area measurements have also been made. 89 80 94 98 a Contact times were 1, 2, 4, and 8 weeks. There was no correlation with contact time within this range. Feed solutions were centrifuged before contact. All others were centrifuged and then filtered (0.4-ym Nuclepore polycarbonate membrane). c Plutonium~239 tracer was also present in the solution. Feed solution was prepared by pH readjustment rather than drying.