Criticality safety of uranium metal scrap in concrete billets

Approximately sixteen tons of mixed uranium and Zircaloy-2 (Zt-2) lathe turnings and abrasive saw fines are generated each year by the Douglas United Nuclear (DUN) fuels manufacturing process for fabricating coextruded Zircaloy-2 clad, metallic uranium fuel elements for N Reactor. Both uranium and Zr-2 fines are pyrophoric and require safe handling and storage procedures. Currently, the processing of enriched uranium requires configuration and mass limits for processing, storing, and shipping to prevent an accidental criticality. The uranium scrap generated at DUN is shipped to National Lead Company of Ohio (NLO) at Fernald, Ohio, for uranium recovery. Control of possible pyrophoricity requires that uranium and Zr-2 fines be stored under water to preclude contact with air, and for off-site shipment, be converted to a more stable form by burning to oxides.