Influent saline solutions do not pose danger to man and environment

The Federal Office for Radiation Protection (BfS) resumes the transport of the saline solutions flowing into the Asse mine to the abandoned Mariaglück mine near Höfer in the rural district of Celle. The Mariaglück operator, Kali und Salz AG, agreed on accepting again the saline solutions for being disposed of in the mine and had given its consent to a corresponding contract. The solutions had not been accepted since June 2008. Prior to this, BfS as the new operator of the facility had proved that the radioactive exposure of the influent saline solutions was far below effective limit values. The values measured now are furthermore clearly below the values measured in the saline solutions previously delivered from Asse to Mariaglück. Thus, these influent saline solutions are harmless and do not pose a danger to man and environment. BfS gave its consent to the citizens’ initiative to take samples from the influent saline solutions and have them analysed at the expense of BfS.

BfS puts straight that solely saline solutions are taken to the Mariaglück mine which are subject to the so-called new saline solution management. Within the scope of this saline solution management particularly the mine ventilation has been changed. This minimises the taking up of tritium via the saline solutions via the mine air. BfS definitely rules out the removal of saline solutions which arise inside the mine and could have come into contact with the emplaced radioactive waste.

Background

Until June 2008, the saline solutions flowing into the Asse mine from the overburden were collected underground and brought to the salt mines of Mariaglück, Hope, and Salzdetfurth. Transports were stopped after one had detected that requirements set out in the provisions of the Radiation Protection Ordinance had not been complied with entirely or only to an insufficient extent. Before transports could be resumed, one had therefore to prove that the requirements of the Radiation Protection Ordinance were complied with.

Approximately 12 cubic metres of saline solutions per day enter the mine from the adjoining rock in depths between 500 m and 575 m. These solutions are collected at three points: The major part of the influent saline solutions is collected on the 658-m level (ca. ten cubic metres per day). Further collecting points are located on the 725-m level (ca. 1.4 cubic metres per day) and on the 750-m-level (ca. 0.2 cubic metres per day).

The saline solutions are negligibly contaminated by tritium existing in the mine air. Due to the new management established by BfS in January 2009, the contact of the influent saline solutions with the mine air is minimised and it is excluded that they blend with radioactively contaminated saline solutions in the mine.

BfS has examined how much tritium from the mine air is taken up by the influent saline solutions per day. Measurement results show that approximately 4 becquerel per litre had been taken up by the solutions per day before the ventilation system was changed. The longer the saline solutions remain in the mine the higher is thus their radioactive exposure. If they are taken above ground as soon as possible, their radioactive exposure can be reduced. This can also be achieved through ventilation.