Federal Office for Radiation Protection secures drums in chamber 7 on the 725-m level

The Federal Office for Radiation Protection (BfS) concluded the works to secure emplacement chamber 7 on the 725-m level in the Asse repository. To prevent a possible damage to the drums due to pieces of rock falling from the roof, BfS had drums stored in the chamber at first covered with salt grit (crudely ground salt). A milling tool was then used on this salt surface which removed loosened pieces of rock from the chamber roof.

A control inspection on 4 May showed that the danger of a piece of rock falling on the drums had been eliminated. The actual security measures have thus been completed. There will be some subsequent works which are, however, not directly needed for the protection of the waste drums.

BfS had started carrying out the security measures immediately upon getting consent by the nuclear supervision after loosened rock had been detected on the occasion of a control inspection of the chamber on 27 April 2009. That means there was the danger that pieces of rock could fall from the chamber roof. As the chamber is unsealed and drums were stored there which were not completely covered with salt, some drums could have been damaged in case of a fall and radioactive particles could have got into the mine air.

Mine air and exhaust air of the Asse mine are continuously monitored for radioactivity. There was no danger to the vicinity of Asse during the course of works.