The UP1 plant in Marcoule reprocessed nearly 20,000 tons of used natural uranium gas cooled reactor fuel coming from the first generation of civil nuclear reactors in France. During more than 40 years, the decladding operations produced thousands of tons of processed waste, mainly magnesium and graphite fragments.
In the absence of a French repository for the graphite waste, the graphite sludge content of the storage pit had to be retrieved and transferred into a newer and safer pit. So, this project consists in the full retrieval and transfer of 15 m3 of water mixed with graphite dust located in the decladding facility, as well as the complete cleanup and decontamination of the pit. The equipment and process necessary for retrieval operations were designed, built and tested.
The process is mainly based on the use of two pumps (one to capture and the other one to transfer the sludge) working one after the other and a robotic arm mounted on a telescopic mast. A dedicated process was also set up for the removal of the biggest fragments. In the pit, the sludge retrieval and transfer operations have been almost completed. Most of the non-pumpable graphite fragments has been removed and transferred to a new storage pit.
As irradiant fragments have been discovered in the pit, specific studies are in progress in order to remove them to the laboratory for dissolution. This work is expected to 2014.