Mining relics with enhanced natural radioactivity

Since most of the ores exploited presented a strong uranium mineralisation, mining residues (waste rock pile material) and in particular residues from treatment (for example tailings, slags) contain amounts of radionuclides from the uranium radium decay chain which make it necessary to consider these residues from the radiation protection point of view.

External and internal radiation exposure

The following exposure paths are most likely to cause a radiation exposure to the population in mining areas:

• the external radiation exposure due to gamma radiation occurring on surfaces influenced by mining activities (material deposits) or in the immediate vicinity of mining facilities (waste rock piles et cetera) and

• the internal radiation exposure due to

  • ingestion of drinking water and of agricultural or horticultural products and mushrooms,
  • ingestion of contaminated dust and soil by children playing,
  • inhalation of contaminated dust and
  • inhalation of radon.

The radiation exposure of the population is particularly influenced by the fact that mining residues and ore processing residues (for example waste rock pile material, slags) have frequently been used for landfills and road construction, and even for house building.

Regional focal points

Due to the geological conditions the largest part of the mining relics with enhanced natural radioactivity is found in

• Saxony,
• Saxony-Anhalt and
• Thuringia,

where silver, tin, copper and other metal mining activities have been an important economic factor since the Middle Ages.

After the Second World War, uranium mining was started, with the SAG/SDAG (Sowjetische Aktiengesellschaft/Sowjetisch-Deutsche Aktiengesellschaft) Wismut being, for a certain period of time, the world’s third biggest uranium producer.

Register of Relics

From 1991 to 1999, the Federal Office for Radiation Protection (BfS) has performed the Project "Radiological registration, examination and evaluation of mining relics (Register of Relics)" in fulfilment of its former legal task of determining the environmental radioactivity occurring due to mining activities in the presence of natural radioactivity in the Eastern part of Germany.

As shown in the table below, this project has come to the following results: In the Laender of Saxony, Saxony-Anhalt and Thuringia a total of approximately

• 20 million cubic metres of slacks,
• 130 million cubic metres of waste rock pile material and
• 30 million cubic metres of processing residues

were deposited on relics which have to be categorised as "radiologically relevant".

However, identifying the radiologically relevant areas and relics does not necessarily mean that a decision is made about the need for remediation measures since these decisions can only be made after a particular case and site have been examined.

Examinations of a similar quality have not been undertaken for the Western part of Germany. Representative investigations which could be used for an evaluation of the radiological importance of mining relics only exist for Bavaria, Baden-Württemberg and Lower Saxony. BfS estimations have shown that approximately only 1 million cubic metres of radiologically relevant mining residues are stored in the Western part of Germany. Some of these relics have already been examined and partly remediated.