Evolution and experience after 5 years of working of a fully automated laboratory for the assay of plutonium in waste and recoverable scraps

To assess the plutonium balance of a reprocessing unit, a laboratory has been specially designed for non-destructive determination of plutonium in wastes and recoverable scraps. The first problem to be solved in the conception of the laboratory is that there is several very differing analytical requirements. For instance, we have to analyze a wide range of weight of plutonium (M Pu<1 g and M Pu>100 g), a wide variety in shapes and matrices (metal, oxides, gloves..) and several isotopic compositions (2%<240 Pu<15%) and americium contents (102 to 104 ppm). We need to manage too the laboratory with only two staff officers in a regular working day (8 hours a day) with an annual throughput of approximately 8000 samples. Several passive methods of determination have been tested and show that only the use of combined gamma ray spectrometry and calorimetry is likely to fulfill our main requirements. Then are given some details on the laboratory with emphasis on the main characteristics and some examples of the obtained performances. The upgrading of the installation's hard- and software is also described. (O.L.). 7 refs., 9 figs