New system for the container conditioning of liquid waste in the German future finale repository 'Schacht Konrad'

The full text of publication follows. On-site the NPP Gundremmingen liquid radioactive waste from the NPP water treatment plant is stored in resin or concentrate collecting tanks. These liquid wastes are cemented in containers in order to temporarily store them in the Bavarian interim storage Mitterteich until they are transported into final repository in 'Schacht Konrad'. With this new system liquid radioactive waste is for the first time conditioned directly into containers destined for final repository in 'Schacht Konrad'. Thus, a very secure and sustainable procedure was developed which also provides high profitability. The conditioning plant for resins and concentrate extracts the liquid waste from the respective collecting tank and transports the waste to the separation tank. This separation tank is dimensioned to ensure complete filling of a Konrad container with only one batch. Within the tank there is the option to adjust the suspensions solids content by either extracting supernatant water or by adding de-ionised water. The specific activity is analysed and after the radiologic data and the solids content are available, the containers are cemented. The required amount of cement is based on the solids content and is automatically added. In the mixer, cement and primary waste suspension are mixed. This mixture is filled into the Konrad container via the allocator. The allocator is a funnel-shaped inlet equipped with a movable tube which makes sure the mixture is evenly spread and also ensures optimal filling of the Konrad container. While filling is ongoing, the container is covered by a lowerable splash guard to avoid contamination. The room situation in Gundremmingen and the specific activities of the primary waste suspension make it necessary to disperse the plant to several rooms. Main components such as separation tanks and pumps are installed in shielded rooms. All activities are conducted remotely controlled and are supervised from the central control panel next to the plant. Thus, the individual radiation exposure is minimized to the greatest possible extent. Accompanying radiological measuring ensures compliance with the transport limit value. With this system, Babcock Noell possesses a procedure that has the possibility to extract completely different kinds of liquid waste from storage containers. The different kind of waste can be radiologically characterized and can be adjusted to their solids content. Since the cementation can be directly filled into a Konrad container, the demands on homogeneity and quality of the conditioned waste product have been absolutely achieved. The modular concept of the plant allows independent use of parts such as transport and cementation unit. The plan also can easily extended or modified to process different kinds of waste or handling of different waste packages. (author)