Jul 18 Container's puzzle assembled
The Dutch company Mammoet has once again visited DD to assist with a heavy-lift operation. This time, the large container holding the shielding ring from the DR 3 reactor needed to be refilled.
SSince autumn 2014, a large container has housed a 17-ton, 2.5-meter-wide shielding ring that was positioned around the top of the DR 3 reactor tank. The space within and around the ring also needs to be utilized, and therefore DD has had a series of specially designed steel containers manufactured by Bladt Industries.
In 2016, the corners of the container were filled with triangular frames. Now, in the summer of 2018, the time had come to fill the last available space in the center of the shielding ring. For this purpose, four quarter-moon containers and one winged cylinder were required.
Similar to the triangular frames, the quarter-moon containers had been filled with shielding plugs prior to placement in the container; these plugs had been mounted as a type of stopper on the uranium fuel elements. The winged cylinder had been filled with fragments of thin steel rods that had absorbed a significant number of neutrons in 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.