Abstract

At the beginning of June 2008, it became known that there was an inflow of contaminated brine into the Asse mine, containing a Cs-137 activity concentration exceeding the exemption limit. Thereupon, BMU charged ESK and SSK with letter of 4 July 2008 with discussing the safety of the Asse II mine and developing a joint statement. The Commissions performed plausibility considerations on data provided by Helmholtz Zentrum München für Gesundheit und Umwelt (operator of the facility) on the following topics:

• The radioactive inventory – including data on uncertainties,
• The radiological measurement programme inside and outside the mine, and
• The possible causes of the detected contamination.

ESK and SSK are of the opinion that

• The operator basically proceeded in a plausible way when compiling the radionuclide inventory. However, the compiled data on the radioactive inventory raise questions relating to the uranium and thorium inventory and to the calculation to determine radionuclides of the natural decay chains.
• Radiation protection in the Asse II mine is not in compliance with the philosophy generally prevailing in nuclear facilities, as it is affected by Mining Law. It is recommended to set up the internal radiation protection rules consistently and systematically.
• The available data provided by the operator on the possible causes of contamination cannot be reproduced. Supplementing examinations to clarify the extent and origin of contamination are imperative.

The “Joint Statement by ESK and SSK on the Asse II Mine – Plausibility Checks of the Data Provided by the Operator” was adopted on the third ESK meeting on 17 September 2008 and on the 227th SSK meeting on 25/26 September 2008.