Criticality Safety Envelope for Receipt, Handling, and Storage of Transuranic Waste

Current criticality safety limits for Solid Waste Management Facility (SWMF) Transuranic (TRU) Waste Storage Pads are based on analysis of systems where mass is the only independent parameter and all other parameters are assumed at their most reactive values (Ref. 1). These limits result in administrative controls (i.e., limit stacking of containers, coordination of drums for culvert storage based on individual drum fissile inventories, and mass limits for accumulation of polyethylene boxes in culverts) which can only be met by redundant SWMF administrative controls. These analyses did not credit the nature of the waste generator process that would provide bounding limits on the other parameters (i.e. less than optimal moderation and configurations within packages (containers)). They also did not indicate the margin of safety associated with operating to these mass limits. However, by crediting the waste generator processes (and maintaining such process assumptions via controls in the criteria for waste acceptance) sufficient margin of safety can be demonstrated to justify continued SWMF TRU pad operation with fewer administrative controls than specified in the Double Contingency analysis (DCA) (Ref. 1)