Outdoor (222)Rn-concentrations in Germany - part 2 - former mining areas.

In the German Federal States of Saxony, Saxony-Anhalt and Thuringia, centuries of mining and milling activities resulted in numerous residues with increased levels of natural radioactivity such as waste rock dumps and tailings ponds. These may have altered potential radiation exposures of the population significantly. Especially waste rock dumps from old mining activities as well as 20th century uranium mining may, due to their radon ((222)Rn) exhalation capacity, lead to significant radiation exposures. They often lie close to or within residential areas. In order to study the impact on the natural radon level, the Federal Office for Radiation Protection (BfS) has run networks of radon measurement points in 16 former mining areas, together with 2 networks in regions not influenced by mining for comparison purposes. Representative overviews of the long-term outdoor radon concentrations could be established including estimates of regional background concentrations. Former mining and milling activities did not result in large-area impacts on the outdoor radon level. However, significantly increased radon concentrations were observed in close vicinity of shafts and large waste rock dumps. They are partly located in residential areas and need to be considered under radiation protection aspects. Examples are given that illustrate the consequences of the Wismut Ltd. Company's reclamation activities on the radon situation.