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

Abstract

Naturally occurring radionuclides (NORs) are encountered in varying concentrations in a wide range of commodities that are mined and processed in Western Australia (WA), including mineral sands, coal, phosphate ores, sandblasting materials, and the production of bauxite, titanium dioxide pigment, copper, zinc, lead, tin, tantalum and the refining of zircon.Because they have the potential for workers to receive annual doses in excess of 1 mSv, 14 mining operations in WA are required to submit an annual report of worker doses to the regulatory authority. This research provides a summary of the workforce demographics and radiation doses reported by mining operations for the 2018-19 reporting period in order to establish a benchmark against which to compare future worker exposures. The 2018-19 data is compared to that presented in the last peer-reviewed research, published in 1994 in order to evaluate changes in worker dose profiles over the intervening period.In 1992-93, the collective effective dose received by 1496 workers across seven mining operations was 2824 man.mSv, whereas in 2018-19 it had decreased to 784 man.mSv for 1474 workers in 13 operations. The maximum committed effective dose (CED) decreased by 76%, from 18 mSv (36% of the annual limit) in 1992-93 to 4.4 mSv (22% of the derived annual limit) in 2018-19. The mean CED decreased by 49%, from 1.8 mSv in 1992-93 to 0.97 mSv in 2018-19.As a result of revised DC's published in ICRP-137 and ICRP-141, the impacts upon the mean CED per unit intake of alpha activity arising from inhalation of insoluble NORs-containing dusts, and contribution to CED from inhalation of radon, thoron and their progeny will require evaluation for individual mining operations in the WA mining industry.

Keywords: dose coefficients; mining; radiation exposure.