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RESULTS OF PILOT STUDIES OF ENVIRONMENTAL RESTORATION OF URANIUM MINING TAILINGS PONDS IN HUNGARY

László Juhász 1 , Pável Szerbin 1 , Zsuzsa Lendvai 2 , Mihály Csövári 2 , István Benkovics 2 , András
Várhegyi 2 , Béla Kanyár 3 , B., Zoltán Várkonyi 3
1 - "Frédéric Joliot-Curie" National Research Institute for Radiobiology and Radiohygiene, POB 101,
1775 Budapest, Hungary 2 - Mecsek Ore Mining Company, POB 121, 7614 Pécs, Hungary 3 - Veszprém University, POB 158, 8201 Veszprém, Hungary

After more than 35 years operation the uranium mining and milling facilities near Pécs city in Hungary
were finally shut down in 1997. One of the most important and most complicated tasks is the
remediation of tailings ponds because of the complexity of chemical, radiological and geotechnical
requirements of the restoration. Tailings ponds are potential sources of radiactive contaminants
through both aerial and terrestrial pathways. The potential risk of environmental contamination from
the latter route has been substantially decreased by pretreatment of the soil (liming) before
construction. The main task of the restoration now is to decrease radon emanation and wind erosion of
the ponds, to give geotechnical stability and environmental friendly shape to the resulting pile and to
prevent soil erosion from the slopes.
In the first pilot study concrete rings of 1 m diameter filled with test layers of different materials were
used for in situ examination of radon infiltration. In total 11 columns were studied, including the
uncovered pond as a reference point. Radon concentrations of the layers were measured by monitors
equipped with scintillation soil probe, and in parallel radon flux was measured on the top of each
column.
On the basis of the evaluation of the results two covering options have been designed for detailed
studies on in-field on territories cover about 2000 m 2 . Radon concentration in the layers, radon
emanation from the surface of the cover were measured, and in situ gamma dose rate at 1 m height
over the cover has been done.
Key words: remedial action, uranium mining and milling, tailings pond, radon emanation