Radiation research priorities in the mineral sands industry

Abstract

Mineral sands processing involves exposure to external and internal radiation sources. The level of exposure is associated with the production of monazite, which contains approximately 6% thorium by weight. External radiation levels may range from less than 1 µGy h-1 to 10 µGy h-1 in the general plant environment, to greater than 150 µGy h-1 in monazite storage areas. Internal radiation may also be significant since airborne gross alpha activity levels from less than 0.05 Bq m-3 to about 5 Bq m-3 are found. Recent estimates of radiation exposure indicate that approximately 15% of workers in the industry exceed 15 mSv y-1. A small percentage of workers are estimated to be receiving radiation doses approaching or exceeding the statutory 50 mSv y-1 limit. Whilst the majority of the radiation dose is contributed by inhaled radioactivity, recent reviews of ICRP models and data reveal that the assessment protocols and default values used in internal dose estimation may be overly conservative, possibly by more than an order of magnitude. The basis for present assessment procedures is briefly reviewed, as are the major areas of uncertainty in internal dose estimation protocols. Priorities for radiation research are suggested and the practicability of obtaining better estimates of internal radiation dose is discussed.

A review of radiation doses and associated parameters in Western Australian mining operations that process ores containing naturally occurring radionuclides for 2018–19

“…According to ARPANSA (2014); Hewson (1990); IAEA (2006); Koperski (1993) the radiation hazard in the production of mineral sands arises from:…”

“…The significance of the potential exposures to workers in the MSI were highlighted by Hewson (1990) who reported that in 1987 the maximum potential dose to a worker was approximately 165 mSv, in excess of three times the annual effective dose limit. Inhalation of LLα contributed ∼90% of the dose; γ contributed ∼10% whilst the contribution from TnP and RnP was negligible.…”

“…According to Hewson (1989) the requirement for reporting entities to submit annual reports of worker radiation doses was implemented in 1984. However the WA Department of Mines and Energy reflects that 'until the recommendations of the (International Commission for Radiological Protection) ICRP in publications 26 and 30 were adopted into WA mine safety legislation in 1986, sample numbers were low, and quality assurance programs were not in place' (DME 1993, p 2).…”

“…Increased regulatory scrutiny from 1986 onwards led to a standardised reporting format, and the development of an electronic database, the Mines Dose Assessment System (MIDAS), which was used by all reporting entities for the recording of monitoring data and the calculation of worker doses (Hewson 1989, Marshman andHewson 1994). Analyses of the estimates of the radiation doses received by the workers employed by reporting entities were reported in several peer-reviewed journal articles, for example DME (1992DME ( , 1993, Hewson (1990). The last peer-reviewed publication was authored by Marshman and Hewson (1994), at which time all seven reporting entities were operating in the MSI.…”

“…The increased regulatory scrutiny noted by Hewson (1989Hewson ( , 1990 was accompanied through 1986 and 1987 by the publication of a series of State mining engineer-endorsed Guidelines that provided the basis for consistent monitoring and dose estimates methodologies by the reporting entities. The Guidelines that were applicable in 1992-93, cited by Hewson (1990, p 6) have been revised, and added to in the intervening period, and are now colloquially referenced as the 'NORM Guidelines' (DMIRS 2020).…”