Intermediate and long-term radiological consequences of an uncontrolled access of saline solution into the Asse mine - 59163

The risk of radioactive contamination in the biosphere surrounding the Asse salt mine has been assessed to determine the possible radioactive exposure to humans if the mine collapses. Geological conditions and anthropogenic activities have made the mine instable and allow salt-saturated ground water to seep in. This uncontrolled brine inflow significantly increases the risk of the mine collapsing. If the mine collapses, the brine will be pressed into groundwater, where the radionuclides can migrate into the biosphere and cause radioactive exposure. The key issue discussed in this paper is estimating the short- and long-term radiation burden for humans under several possible scenarios of radionuclide release. Only a radioecological model able to quantify and estimate processes taking place can generate usable results. This work develops the radioecological model describing both radionuclide migration and the resulting radiological exposure along several exposition pathways. Development of the model took into account the sorption processes, solubility limits and special aspects of decay chain migration. The radiological exposure was estimated under non-equilibrated conditions for the case of short-time expositions. At the end of this paper, the model's background, the results of the computations and a comparison of several scenarios will be presented. The estimating short- and long-term radiation burden for humans under several possible scenarios of radionuclide release in the biosphere surrounding the Asse salt mine is the key issue for further planning of suitable decommissioning options. In the case that the mine collapses, the radionuclide can be pressed out into groundwater and migrate into the biosphere. A radioecological model consisting of two independent tools -- radionuclide migration in groundwater ('Migration') and resulting radiological exposure along several pathways ('Exposure') - was developed. The radionuclide migration can be computed with the analytical solution of one- or two-dimensional dispersion-convention transport equation. The tool 'Migration' allows to quickly estimate the possible ranges of radioactive contamination in the ground water table over time whereas several parameters can be varied. The radiological exposure in the tool 'Exposure' can be calculated according to Gernrman approach AVV [3] or BglB [4]. The calculation model was tested on specific examples and the agreement with the reality was proven. There have been several approaches published on the subject of groundwater flow or radionuclide transfer in Asse mine but no one introduced more exactly radionuclide migration with coupled migration of decay chains and combined it in addition with the computation of radionuclide transfer in the biosphere. (authors)