Containers puzzles assembled

The Dutch company Mammoet has again visited the DD to help with a heavyweight lift. This time, the large container with the shielding ring from the DR 3 reactor had to be refilled.

S Since autumn 2014, a large container has housed a 17-ton and 21/2-meter wide shielding ring that has been sitting around the top of the DR 3 reactor tank. The space in and around the ring must also be used, which is why DD a number of specially designed steel containers have been manufactured by bladt industries.

In 2016, the container's corners were filled by triangular frames. Now, in the summer of 2018, the time had come to fill the last available space in the centre of the foreclosure ring. For this, four quarter-moon containers and a winged cylinder were needed.

Like the triangular frames, the quarter-moon containers within the container had been filled with shielding plugs that had been mounted as a kind of stopper on the uranium fuel elements. The winged cylinder had been filled with bits of thin steel rods that had absorbed some neutrons into the reactor.

On the day of the filling, the container was collected from the storage facility by Mammoet and transported to the so-called active handling hall along a blocked route. In the hall stood DD 's own people ready by the crane. First, the cylinder with four attached wings was carefully placed in the center of the container. Then the quartz canisters were lowered down one by one in the four cavities formed between cylinder, wings and shielding ring.

The containers were designed so that, after placement in the ring, they would stand with just a few centimetres of air between them. This ensured that the container would be as tightly packed as possible – but also made the location a precision work. When each quarter-moon container was lowered, it had to be nudged and adjusted along the way, but in the end the container's puzzle of elements and shielding was well in place. And then Mammoet was able to ship the container back to the storage facility.