Radiological requirements for the long-term safety of the Morsleben repository for radioactive waste (ERAM)

The former GDR government converted the abandoned rock salt and potash mine Bartensleben/Marie on the outskirts of Morsleben (Saxony-Anhalt) into a repository for low-level (LLW) and intermediate-level (ILW) radioactive wastes. The Morsleben repository or ERAM (Endlager für radioaktive Abfälle Morsleben) started operations in 1981 and received a permanent operating licence on 22 April 1986. On 3 October 1990, the Federal Office for Radiation Protection (BfS) was put in charge of the facility. A total of around 37,000 m3 of LLW and ILW with negligible heat-generating capacity were disposed of in the repository until 1998. Mining instability problems and the resulting need for stabilising the mine workings led the Ministry for Agriculture and the Environment (MLU) of Saxony-Anhalt to initiate a planning approval procedure to close the Morsleben repository.

According to the assessment of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU), the Commission on Radiological Protection (SSK), the Reactor Safety Commission (RSK) and the Nuclear Waste Management Commission (ESK), the safety criteria for the final disposal of radioactive waste of 1983 no longer represent the state of the art in science and technology. Requirements regarding the long-term safety have to be established for the closure of the Morsleben repository. The BMU requested the SSK to examine this issue.

The SSK recommends the following:

• Potential radiological exposure in the post-closure phase should not exceed an individual effective dose of 0.1 mSv per year in the case of probable developments and of 1 mSv per year in the case of less probable developments. Optimisation within the meaning of section 6 of the Radiation Protection Ordinance (StrlSchV) is mandatory even if these values are not reached.
• With regard to long-term safety, the SSK recommends calculating radiological exposures on the basis of the most realistic assumptions available as recommended in ICRP publication 103.
• The aforementioned dose values are to be considered as reference values in the case of the Morsleben repository, as this is an existing repository which is to be closed, and planning options are therefore limited. If it should prove impossible to demonstrate compliance with these values in the planning approval procedure, preference should be given to the option causing the lowest radiation exposure and the lowest radiological risks for present and future generations after the optimisation process. Other impacts have to be taken into consideration as well, e. g. the consumption of resources or other relevant social concerns.