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Occupational exposure: Uranium mining and milling workers
Workers involved in the mining and milling of uranium ores are occupationally exposed to ionising radiation. Current industry exposures are low; regulations and required controls minimise the risk to health.
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Exposure to ionising radiation in the mining and milling of uranium ores can come externally from gamma radiation emitted from ore and process materials or internally from the inhalation of radon decay products, uranium ore or uranium product dust. Internal exposure is also possible through the ingestion of materials. The contribution of these pathways is dependent on the local conditions, underground operations are most likely to have higher radon decay product exposure than an open cut mine.
Average radiation exposure in the Australian uranium mining and milling industry is well below the relevant occupational exposure limit of 50 mSv per year. Workers exposure varies depending on what part of a uranium mining and milling operation they work in. Miners typically have exposures that are three times that of a processing workers.
In comparison average background radiation exposure in Australia is 1.5 mSv per year from natural sources and currently Australians are exposed to an average of 1.7 mSv per year from medical exposures.
|Dose Range (millisieverts)||Description||Possible Health Effects|
|Up to 10||Very low dose||None observed or expected (typical background range)|
|10 – 100||Low dose||Plausible health effects but not observed|
|100 – 1000||Moderate dose||Increase risk of cancer
Acute effects at higher end of range (above 500 mSv)
|Above 1000||High dose||Acute effects (burns, vomiting)
Death possible at very high doses (above 5000 mSv)
No health effects have been observed or are expected to be observed at the very low doses normally received in this occupation.
Ionising radiation has been proven to cause harmful short term effects at moderate and high doses received in short periods of time, above 500 mSv, with an increased risk of cancer shown to occur for long term exposures of above 100 mSv.
Low doses, of the order of a few tens of millisieverts per year, are possible in uranium mining and milling without the use of appropriate controls. Historically those levels of exposure caused an increase in lung cancers amongst uranium miners and process workers occupationally exposed. At current exposures the risks are very low and comparable with the risks of exposure from background and medical radiation exposure.
In Australia the use of irradiating apparatus and radiation sources is regulated. Each state and territory is responsible for enforcing their respective radiation safety act and regulations in their jurisdictions. The Australian government is responsible of enforcing the radiation safety act and regulations of commonwealth entities only.
Organisations/employers are responsible for:
- devising, implementing, and regularly reviewing their radiation management plan
- regulatory compliance
- induction and ongoing training of workers, including contractors.
Workers are responsible for:
- following radiation protection practices specified in the radiation management plan
- complying with legitimate instructions of the employer or designated radiation safety officer
- participate in radiation protection training.
Operators of each uranium mine and mill are required to have an approved Radiation Management Plan that complies with the requirements of the Code of Practice and Safety Guide for radiation protection and radioactive waste management in mining and mineral processing. All relevant controls for radiation protection must be included in this plan and the plan must be adhered to.
Controls must adhere to the hierarchy of control. Minimising time, increasing distance and shielding can be used to reduce gamma radiation exposure while ventilation is critical to reduce exposure from the inhalation pathway, when required respiratory protection may be needed as an additional control.
All Australian jurisdictions have uniform annual limits for public and occupational exposure to ionising radiation: 1 mSv for the public and 20 mSv for workers who are occupationally exposed. Despite this, there are different definitions of who is ‘occupationally exposed’ and who should wear personal dosimeters. You can further discuss occupational radiation exposure with your facility’s Radiation Safety Officer or the relevant jurisdictional regulator.
For a pregnant radiation worker, the dose to the unborn child is restricted to the same as a member of the public – 1mSv. (See Management of Pregnant Workers Exposed to Ionising Radiation factsheet)