Criticality Safety Assessment of Transport and Storage of Dross

Dross is a by-product generated from the Cathode Processor (CP), Casting Furnace (CF), and the drip casting process in the processing of EBR-II fuel and the production of HALEU. Currently it is stored in Low Worth Containers (LWCs) and Dross Mold Scrap Containers (DMSs) at the Fuel Conditioning Facility (FCF). Due to the criticality safety analysis, dross material is not allowed to be stored in these containers outside of FCF. To reduce its footprint in the Criticality Control Zone, plans call for removing dross from these containers to approved containers, such as Uranium Product Storage (UPS) and High Throughput Uranium Product (HUP) containers, to the interim storage facility without interrupting the HALEU production. Because dross is a low-density material in the form of powder and flakes, it raises criticality safety concerns while in storage, especially when upset conditions involve moderators. Due to the inhomogeneous nature of the dross and slag composition and the difficulty to fully characterize the material, the dross material is conservatively modeled as fully enriched, fully density uranium metal. Also the non-uranium constituents of the dross material are conservatively ignored to provide a level of operational flexibility. Both HUPS and UPS consist of two parts, compartment part to store dross and container lid provides spacing between containers. Being able to credit the spacing provided by the UPS/HUP top hat, the storage of dross and slag can be accomplished safely in more compact UPS/HUP containers.