In situ evaporation of highly active 99Mo waste fissile solution

AECL Research is the world's main producer of fission product 99Mo generates high-level liquid waste (HLLW) solution containing significant quantities of highly enriched uranium. This solution is stored in a conventional 24-m3 tank. A waste management strategy for the long term management of these wastes is being developed, but facilities for recovering the 235U and immobilizing the fission products in a form suitable for the ultimate disposal are not yet available. We are therefore planning to build additional fissile solution storage capacity, but first, options are being considered to extend the capacity of existing storage. Waste storage extension options included withdrawing solution from the tank and converting it to salt or a calcine, cementation of the waste, or in situ evaporation. In situ evaporation was chosen as the preferred option because it avoided the safeguards, nuclear materials accountancy, high costs, and radiation dose problems associated with transferring and processing the waste to an interim waste form