Risø National Laboratory for Sustainable Energy

An old protective core at Risø National Laboratory for Sustainable Energy had to be removed in 2007. MT Højgaard developed a special method of drilling with air cooling.

Risø National Laboratory for Sustainable Energy had to dismantle parts of their plant in Roskilde, so that the building could be used for other purposes. It required removal of the protective core surrounding the old reactor tank.

MT Højgaard was assigned of drilling in the protective core consisting of lead and aluminium, as well as barite concrete, a very dense material which absorbs radiation.

The task was to drill two metres into the old reactor tank to make a hole for the diamond wire saw in order to dismantle 12 test channels of steel and concrete that pose a particularly large radiation risk.

Air cooling instead of water cooling

Normally water cooling is used for diamond drills. But according to Danish Decommissioning's guidelines it is not permitted to add clean material, namely water, to polluted material. We thus developed a method of drilling with air cooling instead of water cooling. The method was developed with assistance from Hilti in Germany which has extensive experience with nuclear power.

Vacuum cleaner for radioactive dust

The drilling generated about three tons of radioactive dust, which could be a safety risk. To avoid this, we constructed a special central vacuum plant connected directly on the drill with a hermetic rubber ring, which ensures a highly efficient dust collection.