ALTERNATIVE HIGH-LEVEL WASTE TREATMENTS AT THE IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY

A National Research Council committee study recently reviewed technical options for remediating high-level waste (HLW) at the Idaho National Engineering and Environmental Laboratory (INEEL). The waste under consideration was 4,000 cubic meters of solid calcine in stainless steel bins and 5,000 cubic meters of sodium-bearing liquid waste in underground tanks. The U.S. Department of Energy (DOE) requested this study and is faced with decisions on HLW management strategy at INEEL for the disposition of these wastes. Key findings and recommendations of the committee study's report will be presented. For the liquid sodium-bearing waste (a mixed transuranic waste), the committee recommended against continued calcination and mixing of this calcine with the inventory of HLW calcine. Instead, the committee recommended that DOE study various solidification options and select one for use in order to solidify the waste for eventual shipment to a transuranic repository such as the Waste Isolation Pilot Plant. For the solid HLW calcine, the committee recommended a deferred decision on any treatment option until a disposal pathway and its waste form requirements (derived from the future HLW repository's waste acceptance criteria and specifications imposed by transportation and other regulatory restrictions) are established. A risk assessment was recommended to confirm the integrity of interim bin storage. Other report recommendations address waste processing and immobilization steps, with consideration of a variety of final waste forms.