Optimisation of gamma assay for non-destructive radiological characterisation of radioactive waste packages

Objectives and main theoretical and experimental achievements are presented from the execution of the CEC shared cost project Optimisation of Gamma Assay Techniques for the Quality Checking of radioactive Waste Packages. The project is focused on the improvement of the accuracy and reliability of the gamma assay techniques applied to radioactive waste packages, carried out by seven institutions from six countries in the E.U. Optimization is leading by reduction of uncertainties using three techniques: Corrected segmented gamma scanning by mono or multi-energetic transmission source (TC), angular sensitive gamma scanning (AS) and Swivelling or horizontal gamma scanning (SS-HS). A code to simulate gamma scanning system (SOLIDANG 2.0) was developed and validated to model the different gamma scanning systems. The benefits of the transmission and emission tested techniques regarding the current gamma scanning system are determined. Design and construction of test drums are shown to carry out validation, calibration and characterization measurements in order to cover the maximum range of waste nature, source position and density distribution. Our acknowledgement to ANPA-ENEA(I), KEMA (NL), KFZ-Juelich (D), SCK-CEN (B), TUM-RCM (D) y WQCL-NNC(UK), and DGXII of CEC for the permission to present the results in this paper. The spanish contribution is carried out within the framework of the CIEMAT-ENRESA Association Agreement. (Author)