What now for the Asse II repository?
Between 1967 and 1978 low and intermediate level radioactive waste was stored in Asse II, a former salt mine located in Lower Saxony, Germany. However, the mine is not actually suitable for the disposal of radioactive waste. A significant inflow of water and a subtle loss of mechanical stability jeopardise the safety underground – the site is in danger of collapsing and of becoming flooded.
In the media, the Asse II pit is regarded as “Germany’s greatest environmental problem” (in, for example, the Focus and Stern news magazines, and the German daily newspaper Süddeutsche Zeitung). Now appropriate measures have to be taken to the installation without delay and providing safe storage and disposal for the radioactive waste.
Planning status – What is currently happening at Asse?
Following a comparison of different closure options the German Federal Office for Radiation Protection decided to regard the retrieval of radioactive waste from Asse II as the priority option. All waste is to be recovered and permanently disposed of in another, safe repository.
Knowledge about the condition of the radioactive waste and the emplacement chambers are yet not sufficient to assess comprehensively the technical feasibility of retrieving the radioactive waste and reliably estimate the scope of the necessary measures in view of planning the waste retrieval. It has no longer been possible to access most of the emplacement chambers for decades.
As a result the German Federal Office for Radiation Protection wants to collect new facts about the situation in a three-step inspection and therefore investigate the 7th and 12th emplacement chambers at the 750-m level as examples. Approval has already been granted for the first step –drilling into the two chambers – the first findings are expected to be available in the coming months. If the first step of the inspection programme produces positive results, both chambers may be opened in the second and third steps and subsequently the radioactive waste can be recovered on a pilot basis.
An essential aspect in the context of retrieving the radioactive waste is the protection of workers and the local population from dangers which can arise during retrieval, transportation, storage and further treatment of the waste until its final and hopefully safe disposal.
Parallel to all the efforts to retrieve the radioactive waste, measures are also needed which are geared to gradual geomechanical stabilisation of the southern flank of Asse II. Furthermore salt solutions infiltrating the mine are to be continually contained, removed if possible or eliminated by using the solutions for producing concrete for backfilling measures.
Since there is always a danger that the inflowing salt solution becomes uncontrollable and in the worst case it can be necessary to abandon the mine, special contingency plans and preparatory measures are needed in case this situation arises.
The public’s view
Due to the vigilance and persistence of residents living near the repository, the problems relating to Asse have entered public consciousness. An advisory group largely consisting of regional representatives has been actively involved in the proceedings since January 2008.
The advisory group provides an opportunity for sharing information and holding critical discussions between the regional representatives, the operator (German Federal Office for Radiation Protection) and the relevant ministries, i.e. German Federal Ministry for the Environment, Nature Conservation and Reactor Safety, Lower Saxony Ministry for the Environment and Federal Ministry of Education and Research. At the same time the advisory group acts as an intermediary in the concerns and problems of the residents near, and employees at Asse (www.asse-2-begleitgruppe.de).
Who bears responsibility at the moment?
The Lower Saxony parliament entitled an parliamentary investigation committee with the attempt to clarify who should carry liability for the Asse disaster. To facilitate a new start, the relevant competences were re-ajusted.
The German Federal Office for Radiation Protection has been the operator of the Asse II pit since the beginning of 2009. At this federal office plans are elaborated, license applications are made, and the practical work in the pit is coordinated (www.endlager-asse.de).
The German Federal Ministry for the Environment, Nature Conservation and Reactor Safety initiated the advisory process. As the higher-ranking ministry, it has a supervisory competence and the authority to give directives to the German Federal Office for Radiation Protection.
The Lower Saxony Ministry for the Environment is the licensing authority, i.e. a planning approval decision to close the mine, necessary authorisations for preparatory exploration work etc. are granted by this ministry.
The role of Oeko-Institut
Experts at Oeko-Institut contributed to conceptualising the advisory process and formed part of the advisory group from the beginning. Further the institute is observing, advising and evaluating the process on behalf of the German Federal Ministry for the Environment. They are also counselling the Federal Ministry on geological, technical and radiation protection questions in the context of operation and closure of the Asse II pit.
On behalf of the German Federal Ministry for the Environment the institute is independently examining the operator’s documents, developing suggestions for optimising plans, clarifying questions about the proceedings and identifying specific needs for correction. It is also conducting radioecology-related calculations to estimate the potential dose of radiation for the public.
Key aspects addressed by the institute are, for example, the identification and planning of the closure option selected, precaution against hazards arising during operation, and emergency planning in case of uncontrollable influx of water.
“We are learning from the case of the Asse repository how it shouldn’t be done” An interview with Beate Kallenbach-Herbert, Head of Nuclear Engineering & Facility Safety Division at Oeko-Institut can be found here >>