Germany – the decommissioning of a nuclear pilot reactor in Jülich, Germany, has reached an important milestone after Mammoet removed the reactor vessel from the plant during a highly complex operation.
The reactor was a prototype pebble bed reactor which was constructed in the 1960’s. Its purpose was to demonstrate the feasibility and viability of a gas-cooled, graphite-moderated high temperature reactor. It was shut down in 1988 after 20 years of operation. The facility is being decommissioned by AVR GmbH. Mammoet was contracted to design and execute the removal of the most critical part, the reactor vessel, from the plant.
Before decommissioning could begin, a large building, a so called material lock, was constructed over the existing reactor building. This allowed the reactor building to be opened in a protected environment for removal of the reactor vessel.
Later this year the reactor vessel will be lifted out of its support frame and moved from its current vertical position into a horizontal position. It will then be placed in a transport frame, and transported on Self Propelled Modular trailers (SPMT) to a purpose built storage building where it will rest for the next 40-60 years until final storage is available in Germany. Mammoet custom-designed the skidding and lifting equipment to move the reactor vessel from the reactor building into the material lock. The vessel weighs 2,000 tons, is 26 meters high and has a diameter of 7.6 meters. It was lifted from its former position in the reactor building, moved and then placed into a custom-built support frame.
The lifting and transport operations at Jülich took years of meticulous planning and preparation. Mammoet has been active in both nuclear construction and nuclear decommissioning since the very beginning of the industry and has always adhered to the highest quality and safety standards. Every step in the process has been carefully calculated and described in comprehensive and detailed manuals. During the operation, every step is scrupulously prepared, agreed upon with the client and documented. Thanks to these meticulous preparations, the operations have been executed safely, without incidents.