How technically feasible is the partitioning and transmutation of long-lived radiotoxic nuclides in the waste from reprocessed spent nuclear fuel

Spent nuclear fuel or the waste from reprocessing of spent nuclear fuel requires a geological repository which ensures the isolation of the nuclear waste from the biosphere for tens of thousands of years. This is because of the radiotoxicity of a few long-lived radionuclides. This paper reports that if these nuclides were partitioned from the rest of the nuclear waste, it could be stored under less stringent conditions. Since some of the long-lived radionuclides are alpha-emitters, which are the main contributors to the heat release of the stored waste, their removal would allow for a denser form of storage. The partitioned long-lived radionuclides could be transmuted into shorter lived nuclides, into stable nuclides or less radiotoxic long-lived nuclides. The time dependence of the radiotoxicity of a spent LWR fuel (33 GWd/t) is shown. The radiotoxicity is expressed in so-called cancer doses which have been normalized to the cancer doses of uranium ore (dashed line) needed to produce the fuel. The radiotoxicity of the fission products decays fast and crosses the natural cancer risk of the uranium ore at 600 y, while the radiotoxicity of alpha-emitters continues over long periods. The processes to partition and transmute long-lived radionuclides--mainly minor actindes--have been the topics of two dedicated meetings. The conclusion of the last meeting in 1980 in short was that the partitioning and transmutation of minor actinides, especially in fast reactors seemed possible