DO WE ACCURATELY KNOW THE RADIOACTIVE INVENTORY INSIDE A WASTE PACKAGE? A RESUME AFTER 5 YEARS EXPERIENCE IN THE DEVELOPMENT AND OPERATION OF ADVANCED GAMMA SCANNING SYSTEMS

摘要

This paper gives a survey of the main results of research projects performed by members of ENTRAP to improve gamma-ray scanning techniques for radioactive waste packages. Performance characteristics, advantages and restrictions of different assay procedures and correction techniques investigated in these projects are discussed. Case studies are presented which demonstrate the difference in performance between 'standard' and 'improved' assay techniques. Consideration is also given to bias effects resulting from a limited knowledge on gamma-ray attenuation and/or source distribution in the waste matrix. Procedures and tools are presented which may help to decrease respective bias effects or to assess the overall uncertainty. The achievements emphasise that quality control of assay results requires, in nearly all applications, that additional assay techniques are implemented in order to verify the validity of conventional gamma-ray scanning methods.