Technical assessment of processes to enable recycling of low-level contaminated metal waste

Abstract

Accumulationsof metal waste exhibiting low levels of radioactivity (LLCMW) have become a national burden, both financially and environmentally. Much of this metal could be consideredas a resource. The Department of Energy was assigned the task of inventoryingand classifying LLCMW, identifyingpotential applications,and applying and/or developing the technologynecessary to enable recycling. One applicationfor recycled LLCMW is high-qualitycanisters for permanent repository storage of high-levelwaste (HLW). As many as 80,000 canisters will be needed by 2035. Much of the technologyneeded to decontaminateLLCMW has already been developed, but no integratedprocess has been described,even on a pilot scale, for recycling LLCMW into HLW canisters. This report reviews melting practices for removal of radionuclidesand for producing low carbon stainless steel. Contaminants that readily form oxides may be reduced to below de minimis levels and combined with a slag. Most of the radioactivity remaining in the ingot is concentratedin the inclusions. Radionuclidesthat chemically resemble the elements t}_atcomprise stainless steel can not be removed effectively. Slag compositions current melting practices,and canister fabrication techniques were reviewed.