Enhanced natural environmental radioactivity by human impact

Recultivated waste rock pile in a uranium mining area

Radionuclides that occur in the uranium-238, uranium-235 and thorium-232 decay chains are found in the earth's crust. Natural radiation exposure is essentially caused by these radionuclides. Higher concentrations of these radionuclides (in comparison to the geogenic level) can be released into the environment particularly through mining activities but also through the processing of raw materials.

Since 2001, radiation protection is already ensured for industrial residues on the basis of the Radiation Protection Ordinance (StrlSchV) and was additionally regulated since 2017 based on the Radiation Protection Act. Radiation protection measures for contaminated legacies can only be conducted in the post-contamination.

Occurrence

Ores have increased levels of radionuclides - especially uranium ore. This phenomenon is most prevalent in the uranium deposits of Saxony and Thuringia, but it is also evident in the silver, copper, tin, and other mineral deposits across Germany, including the Ore Mountains (Erzgebirge).

Other raw materials with enhanced concentrations of natural radionuclides, such as bauxite and phosphate ores, have been imported on a large scale.

Accumulation in residues during conditioning and processing

During the conditioning and processing of raw materials with elevated concentrations of naturally occurring radionuclides, these radionuclides may accumulate in the resulting residues (including sludges, slags, dusts, ashes, incrustations).

Consequently, their concentrations may increase significantly above the geogenic level. Therefore, it is essential to consider these radionuclides from the perspective of radiation protection.

Radioactive relics

View from a reclaimed legacy of uranium ore mining. These waste rock piles may reach close to residential areas.

In the past such residues were deposited on waste heaps or in tailings ponds or even further utilised by those unaware of - or, in some cases, ignoring - the enhanced radioactivity contained therein. Dissolved radionuclides or solid residues can be released through seepage but also through accidents, such as dam failures in tailings ponds, and in the worst case accumulate in river sediments or on alluvial soils.

Partly, former industrial sites of residues with enhanced natural radionuclide concentration have been redeveloped with buildings. Depending on the specific site and usage conditions such contaminations may, in individual cases, cause radiation exposures to members of the public that necessitates subsequent protection measures.

The current Radiation Protection Act (Strahlenschutzgesetz) is the first to include the field of radioactive relics, and it defines regulations concerning liabilities and required measures.