Development of a partitioning method for the management of high-level liquid waste

Fundamental studies especially focused on the separation of neptunium and technetium have been carried out to construct the advanced partitioning process of fractioning elements in a high-level liquid waste into four groups: transuranium elements, technetium-noble metals, strontium-cesium, and other elements. For the separation of neptunium by solvent extraction, DIDPA proved excellent for extracting Np(V), and its extraction rate was accelerated by hydrogen peroxide. Np(V) was found to be also separated quantitatively as precipitate with oxalic acid. For the separation of technetium, the denitration with formic acid was effective in precipitating it along with noble metals, and the adsorption with activated carbon was also effective for quantitative separation. Through these fundamental studies, the advanced partitioning process is presented as the candidate to be examined with an actual high-level liquid waste