Towards establishing a fit-for-purpose regulatory framework for radiation protection in Western Australia's mining industry: Evaluating mine worker exposures to naturally occurring radionuclides
Date of Award
Doctor of Philosophy (Integrated)
School of Medical and Health Sciences
Mining in the state of Western Australia (WA) formally commenced in the 1840s, and over the ensuing 180 years has evolved to be the epicentre of the Australian mining industry and a significant contributor to the national economy. The lithology of WA is replete with mineralisation that hosts uranium and “critical minerals” required for the global renewable energy sector. The state’s first uranium mine is under development, and high levels of activity are occurring in the state’s nascent critical minerals sector, with 168 WA-based companies pursuing rare earths-bearing minerals, 51 of which are actively drilling on their tenements.
WA’s mineral deposits typically contain levels of the naturally occurring radionuclides (NORs) thorium-232 and uranium-238 that are elevated above the global crustal average. Workers are exposed to NORs during the mining and mineral extraction processes, and radiation doses that exceed applicable exposure standards may eventuate.
The central issue addressed by this research is “what is the potential for radiation exposures from NORs to the significantly increased workforce, and is the regulatory framework fit-for-purpose to ensure radiation doses are kept as low as reasonably achievable?”
The research traces the history of worker radiation doses from 1977 to 2020, finding the maximum dose was 163.4mSv, more than eight times the current derived annual dose limit. Whilst 93.5% of all workers received doses of less than 5.0mSv per year, the potential for elevated doses is ever-present as witnessed by 10.3mSv reported in 2009-10.
The increase in activity coincides with a revision of the dose coefficients (DCs) associated with the intake of radionuclides. The research evaluates the revised DCs and forecasts doses from inhalation of radioactive dusts will nearly double, and lead to workers receiving doses exceeding 5mSv for the first time since 2009-10.
The research raises issues with the evaluation of worker doses and recommends personal dust sampling be prioritised.
The revised DCs reinforce the need for effective long-term management of NOR-contaminated wastes arising from mineral processing activities. The research investigated a technique for the removal and capture of NOR-contaminated scale from a piece of disused mining equipment, reporting capture efficiencies of greater than 90%. The technique has the potential to significantly reduce the environmental footprint of NOR-contaminated wastes and to minimise doses to workers involved in the removal process.
The research finds that the current regulatory framework is fit-for-purpose. However, inter-agency relationships require strengthening, and the capacity of the regulator to effectively regulate the current and future number of mining operations is questioned. The mining industry is similarly vulnerable to capability and capacity constraints – but has failed to respond to issues in relation to competent radiation safety officers first raised by the Winn Inquiry in 1984. Disconcertingly, monitoring of worker exposures to NORs reached a nadir in the final years covered by this Thesis, raising questions as to the veracity of worker doses reported to the regulatory agency.
Academic papers for publication have been developed and are drawn upon in each Chapter. Six papers have been published in peer-reviewed journals, and a seventh is undergoing the editorial process.
Ralph, M. I. (2023). Towards establishing a fit-for-purpose regulatory framework for radiation protection in Western Australia's mining industry: Evaluating mine worker exposures to naturally occurring radionuclides. https://ro.ecu.edu.au/theses/2642