Retrieval and processing of radioactive muck settled in the bottom of radioactive liquid waste storage tanks

Alkaline radioactive liquid waste storage tanks contain huge quantity of chemical muck settled at the bottom of the tank. This muck contains fission products, corrosion products, actinides and other chemicals. As the precipitate remain settled for decades, the elements get converted from hydroxides to oxy-hydroxides and oxides which are difficult to dissolve in mineral acids. Treatment feasibility of this legacy muck was studied by simulating muck using acidic radioactive liquid waste followed by its dissolution and conditioning in borosilicate glass matrix. Dissolution was better in a mixture of nitric acid and oxalic acid medium. Immobilization studies of the muck dissolved solution in borosilicate glass showed that 25% waste oxide could be immobilized in glass matrix whereas when mixed with High Level liquid Waste (HLW), 34% waste oxide could be immobilized in glass matrix. Chemical durability and thermal stability of the glass samples were evaluated and are within the appropriate limit.