Asse II mine
[1] Between 1965 and 1995, the state-owned Helmholtz Zentrum München used the mine on behalf of the Federal Ministry of Research to test the handling and storage of radioactive waste in a repository.
Two chambers are located in the middle part and ten in the southern flank of the mine at depths from 725 to 750 metres (2,379 to 2,461 ft) below surface.
After media reports in 2008[3][4] about brine contaminated with radioactive caesium-137, plutonium and strontium, politicians accused the operator, Helmholtz Zentrum München – German Research Center for Environmental Health, of not having informed the inspecting authorities.
On 8 September 2008, the responsible ministers of Lower Saxony and the German government replaced the operator with Bundesamt für Strahlenschutz (BFS) - the Federal Office for Radiation Protection.
[5][6] In April 2017, operator responsibility for Asse II was transferred from BFS to the Supervisory Board of the Bundes-Gesellschaft für Endlagerung mbH (BGE), under the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.
Other notable waste that is stored in the mine are 497 kilogram arsenic, mercury, tons of lead[12] and animal carcasses from radiation experiments.
Stresses produced in the remaining salt structure during construction of the mine voids are accommodated in the overlying rock.
The overlying rock mass in Asse II moves 15 centimetres (5.9 in) per year, undermining the strength of the mine construction.
"[16] In 1979 a report on the stability of the mine was released by a working group under HH Juergens,[17] which describes an imminent scenario of uncontrolled plastic flow from the surrounding rock on the southern flank resulting in the subsequent loss of the load carrying capacity.
The shifts would lead to an uncontrollable increase in water inflow and make continued dry operation impossible.
[20] The waste is planned to be collected by remotely controlled robots, sealed in safe containers, and stored temporarily above ground.
[25] A significant inflow of water and a subtle loss of mechanical stability may jeopardise the underground mine integrity – the site is in danger of collapsing and becoming flooded.
In 1996, the BFS notified the Bundesumweltministerium that there was a risk of severe radioactive contamination if the mine ran full of water and that further investigation was urgently required.
