Initial evaluation of technical concerns regarding the decommission plan for the Morsleben repository
Parallel to laying out the plan documents to public inspection, the Federal Office for Radiation Protection (BfS), as responsible operator of the Morsleben repository for radioactive waste (ERAM), has been proposing the planned decommissioning project for debate at public events. Radioactive waste is highly dangerous material, part of which has very long half-lives. It is comprehensible that many people have concerns regarding the planned decommissioning of the repository in Morsleben and have raised objections. In the scope of public participation these objections are discussed in a public hearing. Irrespective of this, the BfS will deal in the following with some of these concerns that have been raised on the occasion of informative meetings and published in collective objections.
"It is impossible to furnish the proof of long-term safety."
"The submitted model calculations and prognoses are based on assumptions and assertions and examine unmanageable periods of time."
The periods of time to be examined are based on the international provisions relating to the planning of disposal of radioactive materials. Also the methodical procedure relating to the planning of the decommissioning of Morsleben and the analysis of long-term safety correspond to the international state of the art. In addition to the computational models, also investigations were carried out in the scope of the long-term safety analysis, in which a multitude of parameters were varied.
The periods under review depend on the environmental impact of the waste.
"Experience gained from Asse II shows that prognoses can prove to be faulty after a few years already. Therefore it must be possible to revise faults."
Since unification, the Morsleben repository has been operated and decommissioned according to nuclear law. All proofs of safety need to be furnished according to these regulations and are examined by the plan-approval authority which is independent of the operator. For more than 40 years, however, the former Asse II research mine was operated according to mining law without public participation.
Another difference compared to Asse II is that a long-term safety analysis has already been conducted for Morsleben. So far no report on long-term safety has been presented for the Asse mine. According to the submitted long-term safety analysis, retrieval of the waste is neither appropriate nor necessary from the BfS point of view. Retrieval would involve additional radiation exposure to staff and environment and is thus not justified.
From the BfS point of view, retrieving the waste is neither appropriate nor necessary according to the submitted long-term safety analysis. Retrieval would involve additional radiation exposure to staff and environment and is thus not justified.
"It has not been clarified sufficiently how radioactivity will be released from the sealed repository, which paths it will take and where there will be corresponding exposures."
It cannot be ruled out in the very long term that saline solution will flow into the decommissioned repository. With different computations, the BfS has examined the impacts on the repository and on the radiation exposure to man under unfavourable conditions.
Based on its evaluations, the BfS anticipates that in the post-closure phase, the repository will remain dry for a very long period of time. On account of the decommissioning measures and the geological situation it will take some ten thousand to hundred thousand years for the mine to flood. During this period the major part of the radionuclide inventory would have been decayed and would no longer pose a risk to the environment.
Nevertheless, the BfS has also examined what impacts there would be, should the mine flood rapidly. Even under unfavourable conditions, the protection goal will be kept that has also been taken as a basis for the Konrad repository.
"The Morsleben salt dome is unsuitable for hosting a repository for nuclear waste."
"The numerous different types of rock the salt dome consists of facilitate water paths between nuclear waste and biosphere."
Basically it is correct that an old salt mine, which was operated with the objective of economic salt production, would no longer be chosen for radioactive waste disposal under today’s conditions. However, in this case, the question to be answered by the operator is whether it will be possible to safely seal off the waste stored in the mine, taking into account all knowledge of the rock structure. Naturally, the partially unfavourable structures have been taken as a basis for the safety considerations, too. Conceivable paths for the transport of pollutants in the salt structure have been identified in the scenario analysis and have been taken into account in the long-term safety assessment.
"An old mine cannot meet the requirements of a repository."
"A gigantic, wide network of cavities has been created through the economic utilisation as a salt mine. Therefore the salt dome is lacking thickness and stability."
The necessary stability of the mine openings is given for both the current operation to keep the mine open and for decommissioning. However, Morsleben is an old mine with the typical associated problems such as pieces of rock falling from the roof in blocked mine openings where no waste has been stored. In the long term, the mine will be stabilised further by extensively backfilling the mine cavities in the scope of decommissioning.
"There is at least one location (storage facility H) where a path between groundwater and mine has been detected."
When taking over Morsleben in 1990, the BfS introduced the examination and continuous monitoring of all inflows of brine. The brine flowing into storage facility H is entirely saturated with salt. The average inflow rate is constantly about 12 cubic metres per year (Asse: about 12 cubic metres per day). The place where brine flows into storage facility H is taken into account in the long-term safety assessment (location, inflowing volume). The storage facility H is not located anywhere near the emplacement areas.
"The geological conditions that are inappropriate for storing radioactive waste cannot be replaced by the concrete structures applied for."
The stabilisation of large parts of the mine with the help of concrete in the scope of the decommissioning measures does not serve to strengthen the geological conditions but to stabilise the mine and thus to minimise the convergence rates (= rates at which solution is pressed out) after decommissioning has concluded. Due to mining operations weak points have been created which are isolated and/or strengthened by sealing and concrete structures.
The decommissioning measures (extensive backfilling, sealing of galleries and shafts) ensure the safe decommissioning and sealing off of the radioactive waste from the biosphere in the long term, having regard to the conditions in the mine openings (volume of open drifts and chambers, site-specific properties) and the development of the backfilled and sealed repository to be expected, together with the geological barriers.
"Part of the radiation inventory is unknown, part is illegal."
"The emplaced radiation inventory is only insufficiently known."
- Nuclear power plant operation,
- The decommissioning of nuclear facilities,
- The nuclear industry,
- Research institutions,
- Federal state collecting depots and, directly from small producers, and
- The handling by other users (such as the Federal Armed Forces)
has been disposed of. Furthermore, operational waste of the repository has been disposed of.
- Decommissioning of the Morsleben repository (ERAM) – Plan for the decommissioning of the repository for radioactive waste (in German only)
- Decommissioning ERAM – Operational radioactive waste (in German only )
- Procedural document 12 (in German only)
- Procedural document 90 (in German only)
- Procedural document 91 (in German only)
- Procedural document 92 (in German only)
"With the procedure to close the mine the waste stored intermediately needs to remain in the mine for good. However, its volume amounts to 80 % of the radioactive inventory."
The waste stored intermediately constitutes a major part of the currently existing activity inventory. The entire waste stored intermediately in the underground measurement field is of a short-lived nature (cobalt-60, caesium-137), so that, after ca. 50 to 300 years (10 half-lives), most of its radiation will have decayed.
The radium drum that has been stored intermediately in the eastern field is stored in a bore hole in a manner that is in compliance with the waste acceptance requirements. The long-term safety analysis takes into account the indeed comparatively high activity of the relatively small waste volume.
However, one needs to take into consideration that the waste in the Morsleben repository contains less than 1/500 of the activity contained in the high-level radioactive waste stored in a so-called CASTOR cask.
"There is also an acute risk before the mine is sealed finally."
"The low radiation caused by the operation and possible incidents cannot be accepted for health reasons."
Monitoring measurements are carried out in Morsleben both in the mine (continuing operation) and in the vicinity of the mine. They have been documented comprehensively. There have been no impermissible discharges. They are also not to be anticipated, due to the preventive measures against incidents taken.
"In particular on account of pieces of rock having fallen from the roof so far (which is to be expected for the future as well) corresponding incident analyses are required."
The available incident analyses and the resulting preventive measures against incidents take into account the possible hazard conditions in the framework of the current operation to keep the mine open and the later decommissioning. This also includes risks due to pieces of rock falling from the roof.
"No basic alternatives have been submitted."
"Other than in Asse II, no other decommissioning options, such as retrieval, have been put up for discussion."
Alternative procedures for the decommissioning of Morsleben were examined and analysed in the nineties already. Apart from flooding and the delay of solution movements by means of artificial paths, retrieval was examined, as well (“Technical alternative procedures examined” in the application documents). In the end, the variant now applied for has been chosen because the Morsleben repository can thus be closed in a way that will be safe in the long term.
"The technology applied in Morsleben undermines repository standards."
"If it is possible to compensate geological unsuitability by technology, as it will be done in Morsleben, one gives a strong signal that it is always possible to make an unsuitable repository suitable and thus to build more and more Nuclear Power Plants (NPPs)".
The long-term safety analysis for Morsleben and the decommissioning concept on which it is based take into account the particular feature that the extensive mine workings and the age of the mine openings require great efforts to make the mine’s stability foreseeable by extensive backfilling, to ensure the sealing of emplacement areas in a verifiable manner and thus to hinder the release of contaminated solutions into the biosphere in the long term.
The decommissioning of Morsleben is a special case, given that this repository already had an operating permit in 1990 which had been issued by the German Democratic Republic (GDR) radiation protection authority. According to the currently effective sets of regulations, a licence for the erection and operation of Morsleben could not be granted today.
"The protection goal of 0.3 millisievert (mSv) per year stated in the plan is too high."
"It does not correspond with the state of the art of science and technology in terms of long-time exposure caused by a repository. Already during the period of operation the vicinity of the facility is continuously exposed to radioactively contaminated waste water and exhaust air. Low radiation levels pose a risk, even below the legal limit values."
The value of 0.3 mSv was taken as protection goal for the Konrad repository. This value ensures that, for future generations, no higher radiation exposures will be permitted than are permitted for today’s generation.
For the reference case of the long-term safety assessments (relatively quick flooding) radiation exposures have been calculated that are more than factor 100 below the value of 0.3 mSv.
At no point during the operation of Morsleben was the environment exposed to radioactive waste water. To guarantee a safe operation, there is special canalisation equipment in the above-ground control area which is separated from the normal waste water system. The contaminated waste water collected therein is taken underground and treated as operational radioactive waste, before it is conditioned and disposed of in the western field.
The waste water from the Bartensleben and Marie mines are monitored for radiation. So far the legal and site-specific limit values have not been exceeded. In accordance with the laws and regulations on environmental monitoring, monitoring measurements are carried out in the vicinity of Morsleben, among others by the Saxony-Anhalt Federal State Office for Nature Conservation. So far no enhanced environmental radioactivity has been detected, compared with the natural exposure.
The continuing operation and the decommissioning operation as well as the planning of decommissioning measures including the evaluation of impacts during the post-closure phase are subject to the provisions of the Atomic Energy Act and the Radiation Protection Ordinance. Thus all safety-relevant planning (normal operation, incidents, post-closure phase, etc.) needs to be implemented according to the state of the art of science and technology, taking also into account the principle of minimisation laid down in the Radiation Protection Ordinance. The examination of all plan documents and their licensing are subject to the licensing authority, the Environment Ministry of Saxony-Anhalt.
State of 2017.02.16