The applicant’s introductory statement on the public hearing
- 1970 – German Democratic Republic (GDR) selects Bartensleben mine as central repository for radioactive waste
- Radioactive materials for interim storage
- With the unification of Germany, the Federal Office for Radiation Protection (BfS) takes over the repository
- More waste was emplaced between 1994 and 1998
- The objective of decommissioning is to safely seal off the radioactive waste from the biosphere
- Cavities were backfilled to enhance stability
- The decommissioning concept
- Concept takes into account the site properties
- Decommissioning concept optimised in several steps
- Methodical approach of the decommissioning concept
- Proof of feasibility and functioning by means of a safety assessment
- Scenario analysis
- All protection goals will be achieved
- Calculations prove robustness of the decommissioning concept
- Radiological emission and immission monitoring
- Environmental impact study
- Decommissioning comes up to reliability for today's society and future generations
The public hearing in the scope of the plan-approval (licensing) procedure for the decommissioning of the Morsleben repository started on 13 October 2011. In the applicant's introductory statement, Dr. Michael Hoffmann (BfS) gave an overview of the mine's history and the decommissioning plans.
"The Morsleben repository for radioactive waste (ERAM) was set up in the former potash and rock salt mine near Bartensleben. The mine is part of the Bartensleben/Marie twin-mine shaft installation which is located immediately at the western federal state border between Saxony-Anhalt and Lower Saxony near the villages of Morsleben and Beendorf.
The mine openings of the two mines, that are spaced about 1.5 kilometres from each other, are connected underground.
The shafts Bartensleben and Marie were sunk in 1897 (shaft Marie) and from 1910 to 1912 (shaft Bartensleben). Initially, potash salt was mined for fertiliser production; later on rock salt was produced which was used for example as table salt.
Prior to and during World War II the mine openings served armaments; from 1959 to 1984 parts of the Marie mine were used for underground chicken production.
Between 1987 and 1996, residues from metal processing were stored intermediately in the Marie mine.
1970 – German Democratic Republic (GDR) selects Bartensleben mine as central repository for radioactive waste
As a result of a comparison of 10 salt mines for their suitability to host a central repository for radioactive waste produced in the German Democratic Republic (GDR), the Bartensleben mine was preliminarily selected in 1970.
In accordance with the provisions of the GDR in terms of nuclear energy utilisation, 14,432 cubic metres of radioactive waste and 6,223 sealed radiation sources with a total activity of 180 terabecquerel were stored in the mine (as of 1 July 1991). Radioactive waste was stored in the southern field, in the western field, in the northern field and in the central part of the mine.
The low-level and intermediate-level radioactive waste originates from the Greifswald and Rheinsberg nuclear power plants (operational waste), from GDR research institutions, the interim storage facility in Lohmen and from some small producers.
Radioactive materials for interim storage
During this period, also radioactive materials were emplaced in the ERAM that were to be stored intermediately. These materials consisted mainly of sealed radiation sources with an activity of 390 terabecquerel (as of 30 June 2005). They have been stored in deep boreholes located in the so-called underground measurement field.
Furthermore, the so-called radium drum with a total alpha-activity of 370 gigabecquerel has been stored intermediately in the eastern field. This is about half of the total alpha-activity in the ERAM. Together, the materials stored intermediately amount to about 75 per cent of the total beta-gamma-activity in the ERAM.
The disposal of these materials that have previously been stored intermediately is also to be licensed in the scope of this procedure.
With the unification of Germany, the Federal Office for Radiation Protection (BfS) takes over the repository
Upon the entry into force of the Unification Treaty on 3 October 1990, the licence for the operation of the ERAM, the so-called permanent operating licence granted by the State Authority for Nuclear Safety and Radiation Protection at the GDR Council of Ministers, passed over to the Federal Office for Radiation Protection, BfS. According to the provisions of the Unification Treaty and of the Atomic Energy Act, the permanent operating licence was limited until 30 June 2000. By an amendment to the Atomic Energy Act in 1998, this period was extended to 30 June 2005.
The BfS continued to emplace waste until the Magdeburg District Court prohibited emplacement operations on 20 February 1991 by means of an interlocutory injunction. This interlocutory injunction was lifted again by the Federal Administrative Court on 25 June 1992.
In order to enable emplacement operations beyond 30 June 2000, the BfS filed an application for a corresponding licence on 13 October 1992. This application was restricted to decommissioning on 9 May 1997. In this restricted form, the application is the basis for the pending plan-approval procedure and thus for the public hearing we are currently dealing with.
More waste was emplaced between 1994 and 1998
With the BfS as operator, further 22,320 cubic metres of low-level and intermediate-level radioactive waste and further 394 sealed radiation sources were emplaced in the western, southern and eastern field of the Bartensleben mine between January 1994 and September 1998 on the basis of the permanent operating licence. The total activity of this waste amounted to about 50 terabecquerel (as of 30 June 2005). The major part of this waste originates from the operation of the nuclear power plants located in the old federal states and from the decommissioning of the nuclear power plants of the new federal states.
In accordance with a decision of the Higher Administrative Court for the Federal State of Saxony-Anhalt in Magdeburg dated 25 September 1998, emplacement operations, which had been resumed in 1994, discontinued and have not been resumed to date. Since that time the BfS has solely dealt with the decommissioning of the Morsleben repository.
Currently, radioactive waste with a total activity of about 330 terabecquerel (as of 31 December 2010) is stored in Morsleben. The total activity in the submitted plan is less than 600 terabecquerel (as of 30 June 2005).
The objective of decommissioning is to safely seal off the radioactive waste from the biosphere
The decommissioning measures planned by the BfS ensure the safe sealing off of the radioactive waste from the biosphere and the long-term safety of disposal. In accordance with the safety criteria for the disposal of radioactive waste in a mine of 1983, the term "disposal" describes the removal of this waste for an unlimited period of time, requiring neither maintenance nor control or monitoring measures.
The mine openings will be backfilled in such a manner that, at best, small volumes of solution can flow into the emplacement areas. Thus, only small volumes of contaminated solutions can be pressed out of the emplacement areas, too, due to convergence and gas generation. To ensure this, comprehensive backfilling and sealing measures will be carried out in the mine openings and the shafts Bartensleben and Marie will be sealed with geo-technical barriers.
Originally a cavity volume of ca. 8.7 million cubic metres had been driven in the mine openings. With the help of backfilling measures carried out prior to 1990 (so-called old backfill amounting to about 2.5 cubic metres) and measures to prevent mining hazards in the central part of the Bartensleben mine carried out between 2003 and 2011 amounting to nearly one million cubic metres, this cavity has been reduced to currently about five million cubic metres. Please note that this data has been rounded.
Cavities were backfilled to enhance stability
In order for the mine openings to remain stable, the BfS backfilled cavities in the central part of the Bartensleben mine with salt grit between 2003 and 2011. No radioactive waste has been stored in these cavities. Without these backfilling measures, the so-called "prevention against mining hazards in the central part (bGZ)", it would not have been possible to rule out a future failure of load-bearing elements in this area. Salt rock breaking from the roof could have blocked the path to the emplacement chambers and could have put at risk the staff underground.
The decommissioning concept
The backfilling and sealing measures of the decommissioning concept consist of
- the backfilling of further four million cubic metres of cavities with salt concrete,
- the setting up of 22 horizontal and vertical sealing constructions,
- the complete sealing and backfilling of the shafts Bartensleben and Marie.
A cavity of about one million cubic metres will not be backfilled, in particular for mining and safety reasons. In the immediate vicinity of the waste, this cavity should also allow for expansion of gas whose generation cannot be ruled out.
It will take about fifteen years to implement these measures. They do not include measures to retrieve the waste once the decommissioning measures have concluded, as all accesses to the mine opening and thus to the emplaced waste will be backfilled and sealed.
Concept takes into account the site properties
The decommissioning concept has been developed on the basis of the site-specific facts. Thus it takes into account both the unfavourable and the positive properties of the site. Unfavourable properties of the site, such as the inflow of solution into the Marie mine, will be compensated by the choice of decommissioning measures. Positive properties will be enhanced, such as the isolated location of the emplacement areas eastern field and western-southern field.
The objective of the measures is, apart from ensuring the radiological long-term safety, to rule out an unfavourable impact on the groundwater and to protect the surface from relevant mining-related subsidence.
Decommissioning concept optimised in several steps
The decommissioning concept was optimised in several steps.
At first, various basic decommissioning variants were investigated with the objective to find the variant showing the best isolation potential. The concept of "nearly complete backfilling and sealing of emplacement areas western-southern field and eastern field" was deemed the best variant.
In a second optimisation step it was improved further. Not only did the optimisation aim to minimise possible consequences but also to create a high robustness of the system: In view of the long periods of time over which the emplaced materials can pose a risk and of the complexity of the overall system to be considered, the failure of single components or of the remaining uncertainty – for example about geological parameters – must not lead to a failure of the decommissioning concept.
Methodical approach of the decommissioning concept
The chosen decommissioning concept aims to isolate the emplaced pollutants from the biosphere and thus also from man.
In view of the very large and complex mine openings of the twin-mine facility Bartensleben / Marie and in view of the fact that saline solution has already flown from the overburden into the mine, the methodical approach provides for a confined separation and sealing of the key emplacement areas.
Thus it will be achieved that areas will be separated from the large, complex mine openings that will be isolated and dense for the long term. The development of the required sealing structures was done according to the state of the art of science and technology and is one of the key items of the decommissioning concept.
Another vital item of the decommissioning measures concerns the so-called "residual mine". Its permanent integrity against inflows of groundwater cannot be proven. Measures will be carried out in the residual mine that will create stable and foreseeable conditions and thus enhance in particular the robustness of the decommissioning concept. Due to the comprehensive backfilling measures taken in the residual mine, it will be stabilised in terms of rock-mechanics and the cavity will be reduced that could take up possible inflows of saline solutions. This will reduce the risk of saline solutions flowing into the mine and possible dissolution processes which could damage the sealing structures to the emplacement areas.
Finally, a third important item are the shaft sealings. They will enable the state-of-the-art sealing of the paths existing today as a result of mining activities.
Proof of feasibility and functioning by means of a safety assessment
The BfS has furnished the proof for the functioning, feasibility and robustness of the decommissioning concept with the help of a complete safety assessment. Apart from the examinations of the impacts of operation during the period of decommissioning – for example in the incident analyses – it comprises the possible impacts of the emplaced pollutants over very long periods of time.
The safety assessments are based on the geological, mining, geotechnical, geochemical and radiological data and conditions determined for the site. To determine the necessary data, the BfS has carried out comprehensive investigations. Where it was not possible to determine the specific local design of a parameter, also the uncertainties were determined according to the state of the art of science and technology with the help of statistical procedures.
Also the long-term safety assessment was based on the site-specific data set by investigating the interaction of the various parameters and conditions and anllysing and evaluating the consequences of the mine's decommissioning.
Scenario analysis
In view of the long period examined of up to one million years, it is not possible to guarantee a certain development of the repository system. For example, the future climatic development or the behaviour of the corrosion gases in the emplacement areas is uncertain. Therefore, all imaginable developments of the repository system will be compiled in a so-called scenario analysis and first examined for their probability. Probable and less probable scenarios will be differentiated.
Also, individual cases will be selected that could be of particular importance or whose probability cannot be quantified at all.
For the further investigation scenarios have been selected that overestimate the impacts of other scenarios. These are the so-called covering scenarios.
The safety-relevant processes in three partial areas have finally been modelled for the selected covering scenarios. These three areas are:
- the repository itself, that is, the mine,
- the overburden, and
- the biosphere.
The partial model of the repository mine consists of further partial models such as the emplacement areas or the residual mine. In cases where simplifications were required or no concrete data could be determined – for example with regard to the future geological conditions – data was chosen that safely overestimates the impacts.
All protection goals will be achieved
In addition to unfavourable processes and deliberately effected favourable processes, already existing favourable processes have been taken into account such as the natural dilution in the residual mine or in the overburden.
Thus, the possible radiological consequences over one million years could be examined for different cases of development of the entire repository system. The result shows that all protection goals will be achieved safely.
A decrease in reliability for forecasts over long periods of time cannot be avoided. For the consideration of impacts of radioactive materials, though, this effect is compensated by their radioactive decay and thus the decrease in risk potential.
The dose analyses carried out show that the potential dose maxima for all scenarios clearly occur before the end of the period under review. The calculations are thus also appropriate with respect to their timeframe.
Calculations prove robustness of the decommissioning concept
In order to achieve a still greater reliability as to whether protection goals are complied with and despite of the presented approach with covering scenarios and conservative (very unfavourable) parameters and conditions chosen, all key parameters were varied in large bandwidths in an additional calculation step and several thousand computation cases with different parameter combinations.
These computations, too, prove the safe compliance with the protection goals and in particular the robustness of the decommissioning concept chosen. Even the unfavourable specifications of different parameters or the failure or limited functionality of single decommissioning measures will not lead to a failure of the entire system. All protection goals will also be achieved in cases that are less probable already.
In normal operation, the performance of the measures to decommission the ERAM itself will not lead to an additional radiological exposure to the near and far vicinity of the ERAM. Rather, the discharges of volatile radioactive materials from the radioactive waste stored will decrease. These discharges have been described in the plan as already existing radiological exposure. Once the decommissioning measures have concluded and the ventilation of the mine openings has discontinued, no more radioactive materials will be discharged from the mine openings.
Incidents have been evaluated with respect to their radiological impacts. Their potential radiological consequences are at least factor 1,000 lower than the incident planning values of the Radiation Protection Ordinance.
Radiological emission and immission monitoring
In the operational and decommissioning phase a radiological emission and immission monitoring has been and continues to be implemented according to the principles of the directive for the emission and immission monitoring of nuclear facilities – REI -, modified by provisions of the permanent operating licence. It consists of measurements carried out by the operator which have been monitored and supplemented by immission measurements carried out by the Federal State Environment Authority of Saxony-Anhalt as independent measuring institution. All relevant radiological data in this context is recorded.
Once discharges from the repository can no longer be detected, the monitoring programmes will be discontinued. This will be done after the emplacement areas have been backfilled and sealed.
Environmental impact study
The implementation of the measures to decommission the ERAM will lead to adverse effects in the vicinity of the repository. They will compare with other construction sites of this magnitude. This will be in particular the transport traffic associated with the delivery of construction materials to the ERAM.
All conventional effects of the decommissioning measures have been described in the environmental impact study laid out to public inspection. It arrives at the conclusion that the environmental impacts of the intended decommissioning are permissible and that possible adverse effects such as consumption of area or impact on the natural landscape caused by construction measures will be compensated by appropriate measures.
Decommissioning comes up to reliability for today's society and future generations
Compared with all other conceivable decommissioning concepts, the BfS, as responsible operator, presents a decommissioning concept which provides the most favourable properties with respect to the required long-term safety in terms of the risk potential of the emplaced radioactive waste. The BfS proves that the radiological and conventional protection goals will be achieved safely when this concept will be implemented.
The levels to be taken as a basis for evaluating these protection goals will be clearly fallen below. The implementation of the decommissioning plan represents a responsible handling of the radioactive waste and assumes both the responsibility for today's society and for future generations."
State of 2017.02.16