No definite findings so far according to which the examined site for the sinking of another shaft would be unsuitable

For the retrieval of the wastes from the Asse mine it is planned to construct a new shaft. It is planned to recover large volumes of waste from the mine via this shaft. At the same time, a second shaft makes it possible that more persons than currently permitted can work in the mine.

Currently various exploration drillings are being carried out. They shall establish whether the site that has been selected for exploration following a comparison of different options is suitable for constructing a new shaft. So far, there is no evidence that the site is generally unsuitable for a shaft.

Among others, the Federal Institute of Geosciences and Natural Resources (BGR) has been commissioned with the technical support of the explorations. In the scope of expert talks taking place on a regular basis, members of the BGR presented a paper as of 25 March 2015 that gives the impression of a final report. In a conclusion, this paper questions basically the suitability of the collaring point for the planned recovery shaft. Among the scientists taking part in the expert talk there was agreement that the conclusions in the document were not technically substantiated and that the document therefore needed revising. The out-of-date paper has now been made public. To avoid misunderstandings, the BfS informs in the following about the current status of works:

The BGR paper does not provide any findings questioning the sinking of the shaft. In order to be able to assess whether the selected site is suitable for sinking a new shaft, more comprehensive explorations are required – this is also indicated in the BGR paper. Also, the final evaluation cannot be clarified on the basis of the accompanying explorations alone the BGR has been commissioned with. This will require an overall assessment.

Lack of information and conclusions on the approach

The findings gained from current works relating to the Asse mine are compiled and reassessed on a regular basis. As things stand, retrieving the wastes from the Asse mine is the only option to guarantee long-term safety. Since the old mine has not been licensed as a repository according to the standards of nuclear law, reliable information for planning and conducting a safe recovery of the radioactive wastes is missing in many areas. This information must be identified.

In nearly all partial projects associated with the Asse mine’s remediation it has shown that the exploration results deviate more or less from the assumptions. Also in the present case, some exploration results deviate from the previous presentations. For example, the Staßfurt salt has not been found, as had been expected.

However, drawing the conclusion from this that it is not feasible to sink shaft 5, is scientifically inaccurate. The rock salt of the Leine and Aller series found instead in the course of the explorations is also generally suitable for sinking a shaft. In Gorleben, for example, the shafts were sunk in the Leine series. The major part of shafts in Germany was anyway not sunk in salt formation.

Current status of exploration works for shaft 5

Apart from the surface, vertical exploration drilling to a depth of ca. 900 m, measured data is currently available from a first underground, horizontal exploration drilling. The second exploration drilling is underway. Two more have been planned.

To provide final assessments on the suitability of the collaring point, a number of questions are of particular relevance, such as questions about the existence of a sufficiently mighty salt barrier or the ruling out of brine- or gas-bearing horizons. So far, there is no evidence that the site is generally unsuitable for a shaft.

How was the collaring point determined?

In 2011, the BfS had commissioned an order to determine what geographical locations in the immediate vicinity of the Asse II mine would be suitable for sinking a new shaft. For this purpose, criteria were laid down in a public and transparent procedure together with the Asse-2 Monitoring Group. Safety margins to existing and instable salt-extraction chambers and water-bearing rock layers are for example determinative.

According to these criteria, the BfS has determined two potential areas: One to the west of the facility and one to the east, i.e. where the exploration works are currently carried out. Since one of the collaring points is located above potash layers, the exploration works were taken up at the most promising location.

The report on the determination of the collaring point is available on the internet.