Non-destructive material characterization of radioactive waste packages with QUANTOM®

For the safe intermediate storage and final disposal of radioactive waste, waste packages have to meet the waste acceptance requirements defined by national licensing and supervisory authorities. In Germany the federal company for radioactive waste disposal BGE (Bundesgesellschaft für Endlagerung) has established waste acceptance requirements for the geological repository Konrad and is responsible for the qualification of radioactive waste drums. The material characterization can be performed on the basis of existing documentation or, if the documentation is insufficient, on further destructive or non-destructive analysis. Non-destructive methods are very much preferred over destructive methods, as the latter lead to additional exposures of operating personnel, increase the waste volume and costs, and are very time consuming. Existing non-destructive methods, as integral and segmented gamma scanning or neutron counting, only determine the isotope specific activity but do not allow to quantify other non-radioactive hazardous substances. These should have been documented during creation, conditioning, and packaging of the waste, but especially for legacy waste this documentation is often of poor quality or even missing. This makes it difficult to prove that the waste does comply with the acceptance criteria. Thus, there is an urgent need for the non-destructive determination of the elemental and chemical composition of the content of waste drums. This gap is to be closed by the QUANTOM® (QUantitative ANalysis of TOxic and non-toxic Materials) measurement device. This device will measure the mass fraction of non-radioactive elements within a 200-l drum using the prompt gamma neutron activation analysis. A segmented scanning approach enables a spatial resolution for the mass quantification. An overview of this project and some results obtained with the first prototype of the QUANTOM® device are presented. A focus will be put on the determination of the online neutron flux measurement subsystems, such as the primary fast neutron flux emerging from the neutron generator as well as the spatially resolved thermal neutron flux surrounding the waste package. The joint project QUANTOM® is being funded by the German Federal Ministry of Education and Research under grant number 15S9406A / B / C. The responsibility for the content of this publication lies with the project partners.