Questions and answers

Date

29/01/2010

Will the entire waste from Asse now be taken to Konrad?

A final answer to this question can only be given after the waste has been removed from Asse and analysed. It needs to be clarified what substances have actually been stored in Asse. Konrad has been granted a licence for certain substances and for a limited volume. If one intends to emplace additional substances or amounts of waste another licence must be granted. The Konrad mine is currently the only repository licensed for the disposal of low-level and intermediate-level radioactive waste in Germany. Therefore, it is considered a possible repository.

Does the licence for the Konrad repository also include waste stored in Asse?

The Konrad repository has been granted a licence for the disposal of waste with negligible heat generation. The key issue is not the origin of the waste but the compliance with the requirements set out for Konrad. The licence for the Konrad repository limits the total waste volume to 303,000 cubic metres and the total activity. Additionally, maximum limits for individual radioactive substances have been established.

What is the amount of waste Konrad has been granted a licence for?

The licence for the Konrad repository provides for the storage of 303,000 cubic metres of low-level and intermediate-level radioactive waste with a total activity of 5,150,000,000 gigabecquerel, approximately 280,000 cubic metres of which will be utilised according to the previous planning.

What is the waste in Asse composed of according to the present state of knowledge?

125,787 waste packages were emplaced in the Asse II mine between 1967 and 1978. 1,293 waste packages (200-l drums) contain intermediate-level radioactive waste (MAW), 124,494 waste packages (drums of different size, parts of them coated with concrete) contain low-level radioactive waste (LAW). The waste is not sorted according to material or radionuclides but is a mixture of different substances. Among others, these substances contain the radionuclides cobalt-60, nickel-63, strontium-90, caesium-137, plutonium-241. The by far largest part of the total activity directly or indirectly originates from all nuclear power plants operated at that time.

Is it correct that the waste from Asse poses a higher risk than the waste intended for disposal in the Konrad repository?

After the Konrad repository will have been completed, only such waste will be stored there for which a corresponding licence exists and which can be safely transported. According to today's state of knowledge of the composition of the waste in Asse, its total activity would be about one-tenth of a per cent of the total activity licensed for Konrad.

Why has BfS argued for retrieving the waste?

According to the present state of knowledge, it is very probable that long-term safety can only be ensured for the option of retrieval. This option is based on the condition that the stored waste is in a state which allows for safe retrieval.

What amount of waste needs to be disposed of later on?

At the time of emplacement, the total activity of the waste in Asse amounted to 7,800,000 gigabecquerel, which approximately corresponds to one-tenth of a per cent of the licensed total activity of the Konrad mine. In the case of a complete retrieval of all waste and the contaminated salt grit, the volume of the waste retrieved from Asse and packed in a way that is suitable for disposal would probably amount to about 100,000 cubic metres.

Where will the retrieved waste be conditioned and where will it be intermediately stored?

As far as it is technically feasible, the waste packages to be recovered are to be compacted and packed underground. Further conditioning into licensed repository containers would then have to be carried out above ground. From today’s point of view, the waste would be intermediately stored in the direct vicinity of the mine, before the containers are taken to a licensed repository.

Have companies already been charged with the retrieval of the waste?

No. Currently, the sampling of the drums is in the planning stage. Just like a decision about interim storage, tenders for charging companies with the retrieval of the waste belong into a later planning phase.

How long will it take to retrieve the waste and how much time will remain?

A period of ten years is currently prognosticated for the process of retrieval. According to expert reports, the mine’s stability is ensured until 2020. It is to be clearly extended through stabilisation measures, such as the backfilling of residual cavities where no waste has been stored.

What emergencies can occur during the process of retrieval?

On account of the instable situation of the Asse II mine, there is the permanent risk of an uncontrollable inflow of saline solutions. For this case, BfS has developed an emergency plan. Apart from this, various scenarios with different radiological consequences are possible, such as waste packages crashing on a transport or a reloading gallery underground. In order to prevent a release of radioactive substances into the environment in that case, provisions must be taken for such scenarios.

What provisions does BfS make for an emergency?

It is of particular importance to reduce the amount of the collected influent saline solutions to 500 cubic metres per day. Thus, much larger amounts of influent saline solutions can be controlled (currently, approximately 12 cubic metres per day flow into the mine). All emergency measures are designed for the proceeding during retrieval and for possible emergencies. This also includes the most unfavourable case, the “drowning” of the facility – in that case, emplacement chambers would be encapsulated with a special type of concrete, and shafts and galleries would be backfilled as quickly as possibly in order to prevent the release of radionuclides for as long as possible.

What was the aim of the comparison of options?

The aim of the comparison of options was to select the best possible decommissioning option for the Asse II mine. It must be possible to technically implement this option within the period of time available under the given unfavourable conditions. Also, the issue of requirements for granting a licence had to be included in the evaluation.

How many emplacement chambers exist and what is the waste volume to be retrieved?

When the radioactive waste is retrieved, it will be recovered from the 13 emplacement chambers and taken above ground. The LAW waste (low-level radioactive) has been stored in eleven emplacement chambers on the 750-m level and in one emplacement chamber on the 725-m level. The emplacement chamber containing the MAW waste (medium-level radioactive) is located on the 511-m level.

The volume to be retrieved amounts to approximately 62,000 cubic metres, this volume consisting of about 48,000 cubic metres of pure waste volume and about 14,000 cubic metres of contaminated salt grit. This waste needs to be placed into packages in a way that it is in compliance with the waste acceptance requirements. Thus, the waste volume probably increases to about 100,000 cubic metres.