Estimating radioactive nuclide inventories in waste drums with low- and intermediate-level waste from dismantling of a spent fuel reprocessing plant

The Karlsruhe reprocessing pilot plant, WAK, will be dismantled in the next few years. The radioactive nuclide inventory in the radioactive waste has to be determined according to legal requirements. During the operation time of WAK the declaration of radioactive waste was straightforward: the spectrum of nuclides in the waste was correlated to the fuel actually being processed. However, in decommissioning and dismantling a reprocessing plant, the accumulation of several nuclides in different parts of the plant has to be considered very carefully. Therefore the specific radioactive nuclide inventories must be determined by taking samples of the equipment in the rooms and cells. The samples are analyzed to their key nuclides (Co-60, Cs-137 etc.) and are representative for the dismantling of the equipment. The analytical results are the basis for the declaration of the waste. Nuclides which cannot be analyzed easily are correlated by a cell-burnup calculation (KORIGEN) and chemical knowledge. As was done during the operation time the radioactive waste is then declared on the basis of a shielding calculation and the measured dose rate on the surface of the drum