PIDIE an overview of the Plutonium Isotopic Determination Inter-comparison Exercise by the ESARDA Working Group on Techniques and Standards for Non-Destructive Analysis.

PIDIE (Plutonium Isotopic Determination Inter-comparison Exercise) is one of the projects of the ESARDA Working Group on Techniques and Standards for Non-Destructive Analysis. PIDIE is placed against the historical background of the general development of international standards. Its results are also reviewed in the light of the original purpose of the project. Sets of seven sealed Pu samples of different isotopic composition, each containing 0,45 grammes, were sent to the nine participating laboratories for three separate determinations of the unknown isotopic composition. Afterwards separate small samples taken from the same batches were analysed by mass-spectrometry, in order to have reference values for the evaluation of the results. The aim was to test the y-spectrometry methods for measuring Pu isotopic ratios in a large range of isotopic composition, to investigate error sources and, if possible to improve the knowledge of y-emission probabilities. An additional question was to examine the possible improvement of such measurements using reference samples. No important bias has been observed in the results of this inter-comparison. The apparent improvement in the precision and accuracy of the results seems to arise from both better equipment and more elaborate spectrum evaluation methods.