Approximately five years of process improvements, and production line waste handling experience have been accumulated since the newest tank farm, 241-A, was placed into operation. Process improvements and modifications have resulted in waste volume reductions by decreasing the quantity of solids remaining in the liquid wastes from a unit of production. The resulting concentration of fission products has produced mildly boiling solutions in the storage containers permitting further waste volume reductions. Waste handling procedures have been modified to provide safe interim containment of these concentrated wastes, but restrict the usable space in existing facilities. The resulting concentration of fission products in existing facilities has a maximum heat generation rate of 10 tP 15 BTU/hour per gallon stored and the contents have a potential boiling life in excess of the anticipated life of the structure. Concentrations of fission products stored in the anticipated smaller tanks have an average heat generation 75 to 100 BTU/hour per gallon stored. A preliminary design criteria is needed as the basis for an engineering evaluation of tank design concepts to obtain maximum benefits from our operating experiences in the light of the future wastes and the Chemical Processing Department waste management program.