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20
International Conference 2011

Uranium, Mining and Hydrogeology VI




Conclusions UMH II

It was for the second time that scientists and engineers met in Freiberg to discuss the topic of Uranium Mining and Hydrogeology. As already in 1995 Prof. Broder Merkel´s chair invited to this international conference under the patronage of State Minister Vaatz.

Thanks to the financial support of the Saxonian State´s Ministery of Environment and Country Development international acknowledged experts from USA, Canada, Australia, Belgium, France, England, Russia, the Ukraine were invited to Freiberg. In his welcoming speech Prof. Merkel pointed out that groundwater gets much less public attention compared to surface water thus rivers and lakes present only a small fraction of the earth´s freshwater supply and are much easier to regenerate than groundwater.

In discussing nuclear energy threats the threats resulting from Uranium Mining and it´s estates are often totally forgotten. Yet threats from Uranium Mining are much more obvious and relevant than radiation from castor containers or radioactive waste´s permant disposal. 250 participants from 25 countries listened to more than 60 talks and discussed more than 40 posters. During three concluding work shops statements were evolved concerning topics like "natural redevelopment methods" "surveying programs" and "modeling of reactive transport".

During the conference it became clearly visible that effects of Uranium Mining will still be noticeable in hundreds of years in the near and far field of former mining sites. Sustainable rehabilitation and monitoring has to be set for these periods of time. Many small mines, heaps and tailings pose a special problem since they have been abandoned in the early sixties by the former Wismut SDAG and changed into the possession of communities or forestry administration, cause these sites are not being remediated by the present Wismut GmbH. For the redevelopment of these deposits there are no financial means available. Just as little as for the cleaning up of ancient mining deposits which can as well show a cobsiderable amount of radiation since pitchblende was heaped by ancient miners as dead rock.

Especially for these small sites one works to develop natural remediation methods that are cheap in installing and have no running expenses. In USA and England they have already made good experiences with so called wetlands. The fixing of Uranium and radionuclides happens by means of microorganisms consuming oxygen under swampy conditions and therefore building up a reducing environment causing a sustainable fixing of pollutants.

Indisputable is that organic components have a considerable influence on the migration of Uranium and its radioactive subsidiary products. Yet organic matter can either mobilize or immobilize uranium and its successors. The long-term consequences resulting in piling private and industrial waste on heaps or tailings of former uranium mining is largely unknown today and demands further investigations.

Further more it became clearly visible that Uranium itself should reach only low concentrations in water not so much because of its radioactivity but because of its chemical toxicity. At present 0,02 to 0,002mg/l is discussed internationally and also for Germany as a MCL (maximum contamination level) for Uranium. The present recommendation of the German Radiation Protection Commission is 0,3mg/l and does not regard the ecological toxicity in anyway.

For surveying the Uranium mining deposits adapted monitoring systems have to be developed that guarantee recognizing possible changes in the migration of pollutants even in a hundred years to start adapted counter-measures in time.

Wismut GmbH´s rehabilitation projects on large sites like Schlema, Crossen and Ronneburg work out more or less according to plan. Due to a cooperative work between applicant and the license authorities most licenses could have been given in time. The in situ leaching mining Königstein should be flooded as soon as possible to 140 meter above sea level. Affects to the aquifer above which is used for drinking water purposes is out of question. There will be further optimizations for the remain flooding from the present second flooding experiment.

Newly developed numerical models are able to simulate groundwater movement and complex chemical reactions both in the water and at the water rock interface permit a comparison of different rehabilitation methods. The reactive transport code TREAC was developed in Freiberg at TU Bergakademies chair for Hydrogeology taking into account the special demands of radioactive contaminants.




© A. Berger <umh@geo.tu-freiberg.de>, 17.05.2010, http://www.geo.tu-freiberg.de/umh/UMHII_Conclusion.htm