Investigations on the extraction of Pu from MAW

A suitable method to treat burnable middle active wastes (MAW) is wet ashing. The waste is carbonized in concentrated sulphuric acid at 2500C and oxidized by adding conc. HNO3. The final product of the wet ashing is a suspension of organic and inorganic solids in conc. sulphuric acid. In order to determine the suitability of wet ashing regarding plutonium separation from MAW, the decomposition power of the acid solution with regard to the different highly annealed plutonium oxides or plutonium-uranium mixed oxides was investigated, as well as the distribution of plutonium between the concentrated sulphuric acid and the solids. Due to the slight solubility of plutonium sulphate, there is an expected enrichment of plutonium in the solid residue which is washed out with dilute sulphuric acid. In order to separate the plutonium from the washing solution, extraction methods (prim. amines), ion exchange and coprecipitation methods are examined. The target of the latter used method is the earliest possible confluence of the method with known plutonium separations in nuclear technology. (orig.)