Operational experience relating to measurement of plutonium in solid and liquid waste streams from fast breeder reactor fuel reprocessing

Fuel at the Dounreay Nuclear Power Development Establishment (DNPDE) from the Prototype Fast Reactor has been routinely reprocessed for about two years. These reprocessing operations have been subjected to continuous safeguards both by Euratom and IAEA. A primary safeguards feature of the reprocessing plant is the use of nuclear material accountancy and this paper deals with techniques used for the measurement of plutonium in solid and liquid waste streams during two reprocessing campaigns. The solid waste streams have been designed to allow eleven non-destructive analysis (NDA) systems to be used in order to make plutonium measurements for plant control, accountancy and safeguards, thus also ensuring that the correct waste disposal route is selected. The major problems associated with these NDA measurements have been in the head-end area of the reprocessing plant, as a result of the high associated #betta#-activity present and of the neutron emission from ingrown curium isotopes. The liquid waste stream measurements are achieved by tank sampling followed by wet chemical spectrophotometric or radiometric analysis in support laboratories. Highly active raffinates are analysed in a suite of shielded α#betta##betta# facilities using remote handling techniques. Medium and low active streams are analysed by similar techniques but the sample handling problems are much less severe. The quantities of plutonium measured during the first two campaigns are given for the various solid and liquid waste streams. Results are given of cross-check analysis of leached hulls which compares the NDA values to destructive analyses. Quality control data are given on the performance of the wet chemical colorimetric methods