02 May Heavy-Lift Specialists Remove Risø's Reactor Plug

They have raised the nuclear submarine Kursk from the bottom of the Arctic Ocean and uprighted a toppled 80-ton crane at the Lindø shipyard after the 1999 hurricane. Now, the Dutch company Mammoet, with its powerful cranes, is tasked with extracting a massive metal plug from Risø's largest research reactor.

In the coming weeks, Danish Decommissioning is planning a challenging operation, which will be the only one of its kind in Denmark. A 22-ton shielding plug, located within the tank of Denmark's largest research reactor, must be lifted. This necessitates specialized cranes and extensive safety measures.

The plug – professionally referred to as the top shield plug or TSP – seals the radioactive tank completely, much like a stopper in a thermos flask. It must be lifted and removed to allow Danish Decommissioning to cut open the reactor tank from within. The moment the plug is lifted, a movable lid will be rolled over the tank as a new shield, ensuring that the intense radiation remains continuously contained.

Part of the challenge lies in the confined space. The reactor tank is encased within a square concrete tower, measuring 6 x 6 meters in width and 10.5 meters in height. The tower is situated in a tall, cylindrical hall with only a few meters of working space towards the walls. The Dutch heavy-lift company Mammoet specializes in tasks of this nature and was the obvious choice to undertake this assignment for Danish Decommissioning.

Mammoet has repeatedly lifted and removed entire reactor vessels from nuclear power plants across Europe. Furthermore, the company is tasked with installing the new roof on the concrete sarcophagus encapsulating the Chernobyl plant.