INTERCOMPARISON TEST FOR QUALITY ASSURANCE OF ACTIVITY MEASUREMENTS

摘要

Characterisation of radionuclide inventories in nuclear waste packages for storage, transport and disposal is performed in routine operation by correlation of hard to measure nuclides to so called key nuclides, which can be measured directly on the package. The correlations are derived from statistical evaluations of activity measurement data. An intercomparison test was set up to check the comparability of results gained by different radiochemical analytical techniques and to validate to some extent the correlations on which activity characterisation is based. Measurements were performed by five different European participants on samples from two major waste streams from NPP operation, ion exchange resins and evaporator concentrates. The results demonstrated rather good agreement between the activity concentrations determined by the participants. The scatter of the measured activity concentrations is considerably lower for all evaluated nuclides than the range of the values available from a data bank for measurement data on NPP waste streams established in an earlier step of the same project. On the other hand the confidence intervals of activity concentrations predicted from correlations based on this data bank cover the measured values from this test for all radionuclides. Thus the comparison confirms both, the comparability of the measurement results and to some extent the reliability of the correlation method. It thus gives confidence in its predictions and justifies its application in routine waste characterisation.