Distribution of 230Th in milling wastes from the irovski vrh uranium mine (Slovenia), and its radioecological implications

Thorium-230, together with 238U and 226Ra, was determined (mainly by γ-spectrometry) in samples from the waste piles at Bor t and Jazbec in the vicinity of the former uranium mine at irovski vrh, Slovenia. Activity (and in the case of uranium, also mass) balances for these nuclides were constructed for the overall operation of the mine and yellow cake plant, using experimental data and known data on ore and uranium production, and nuclide emissions to the environment. All the 226Ra resulting from ore exploitation is presently contained in the Bor t tailings pile. However, because of the very high content of 230Th in red mud deposited at Jazbec, where 60% of this nuclide is found, the majority of 226Ra will be found at the Jazbec pile in the future, due to its ingrowth from 230Th over the next few thousand years. The long-term radioecological consequences of this untypical finding for rehabilitation of the site, and its safe management are discussed in this paper.