Mining and underground excavation
Mining and underground excavation
Under the provisions of the Radiation Act, STUK oversees mining activities in cases where workers or the public are or might be exposed to natural radiation that exceeds reference values. If uranium or thorium are extracted in the mine, STUK oversees the mine’s activities as provided in the Nuclear Energy Act.
An activity regarded as mining and exploration for uranium comprises all activities where the amount of uranium produced in the course of one year exceeds 10 tonnes, and where the average uranium and thorium content in the processed ore exceeds the limits laid down in Section 2 of the Nuclear Energy Decree, and where the combined concentration of uranium and thorium in products produced in the refinement process exceeds 0.5 kilogrammes per tonne.
Mining and underground excavation aimed at producing and enriching uranium or thorium is subject to permit by the Finnish Council of State. The export and import of ore concentrate with a uranium or thorium content is also subject to license by either the Radiation and Nuclear Safety Agency or the Ministry for Foreign Affairs of Finland, depending on the case.
Currently, Finland has no uranium mines. In the Paukkajanvaaras area in Eno, North Karelia, an amount in excess of 30 tonnes of uranium was mined at the end of the 1950s and in the beginning of the 1960s. As a result of this mining operation, a quantity of gangue and sand from ore dressing were deposited in the area, with radiation levels clearly exceeding the natural background radiation level. This waste was dealt with in the mid-1990s, and in 2001 STUK found that the tailings from this mining operation were disposed of.
Mining and underground excavation other than uranium mines
Under the provisions of the Radiation Act, STUK also supervises mining and underground excavation where such activity is not aimed at extracting uranium or thorium.
Prior to the start of activities, the party responsible for the activity is obligated to notify STUK of
- Mining activities specified in the Mining Act;
- Excavation and other work in underground passageways or tunnels, where an individual worker’s total annual working time is more than 100 hours;
- The processing, use, storage and utilization of materials and waste that contain natural radiation, where uranium 238 and thorium 232 or the radioactivity of their decay products is greater than one becquerel per gram.
The key information on radiation safety related to the activities or the arrangement of these activities must be reported.
In the aforementioned situations, exposure to natural radiation must be investigated and the report must be submitted to the Radiation and Nuclear Safety Authority. STUK can obligate the actor responsible for the activity to submit a report also in other situations, if the radiation dose that workers or the public are subjected to, the radon content of the workplace or a worker’s exposure to radon may be greater than the reference value.
If the report finds that the reference value for exposure to natural radiation has been exceeded, the party responsible for the activities must carryout measures to limit natural radiation. If, in spite of these limiting measures, the reference values for exposure to natural radiation are still exceeded, the activities are subject to a safety permit granted by STUK.
A survey of the environment’s radioactivity and continuous monitoring of the environmental radiation level may also be required for operations where uranium or thorium are not produced.
Those working in mines are exposed to radon
STUK regularly carries out radon testing in all underground mines. External radiation and radon gas expose those working in uranium mines to radiation. While radon may be of particular concern in underground mines, working conditions in them can be raised to an acceptable level by putting in place sufficient ventilation. Also underground mines other than uranium mines may contain radon.
The entry of radon from a mining area into the air and the environment depends on factors such as the uranium content of the ore and the mining method used. Adverse impacts can be reduced through proper planning of operations. Radon concentrations are also diluted quickly in outdoor air as radon is carried away from the mining area.
Linkkilista Mining and underground excavation
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