A review of radiation doses and associated parameters in Western Australian mining operations (2020-23).

ABSTRACT

The Western Australian mining industry is a global supplier of critical minerals, including lithium and rare earths. The lithology of these minerals is associated with elevated concentrations of naturally occurring radionuclides (NORs). An increase in the number of mines producing the minerals has witnessed a commensurate increase in the number of workers potentially exposed to the radiation from NORs. The regulatory framework in Western Australia underwent significant change in March 2022. Mining operations whose workers are likely to receive doses greater than one mSvy-1 are referenced as relevant mines and are required to submit an annual report of worker doses to the mining regulator. This research provides an overview of the new legislative framework and updates the information in Ralph and Cattani (2022) to include data derived from annual radiation doses reported by relevant mines in the period spanning 2020-21 to 2022-23. In 2022-23, 38 mining operations were identified as relevant mines, an increase of sixteen from 2020-21. The mean effective dose (ED) reported in the three-year period was 1.0 mSv, and the maximum ED was 4.9 mSv. The collective effective dose of the mine worker population reached an historical maximum of 2,339 man.mSv in 2022-23. Inhalation of long-lived alpha emitting radionuclides in dust remains the most significant contributor to worker doses. Inhalation of radon-22, radon-220 and their short-lived progeny, once considered as a negligible contributor to worker doses, is the second most significant exposure pathway. A declining trend in the number of samples collected per worker is highlighted as requiring remediation to provide confidence in the reported dose estimates. The transition to the new legislative framework for radiation protection in mines has been supported by the publication of guidance materials which have been widely endorsed by the industry. .