Solid-state microdosimeter for personal radon dosimetry in mines and caves

Radon gas can be found naturally from the materials in which it is formed that contain traces of uranium, actinium, thorium, or neptunium. Uranium and radium are commonly found in soil, rocks and water, especially in enclosed spaces such as mines, caves, cellars or poorly ventilated houses. Radon levels found in uranium, coal and metal mines, especially underground mines, can be up to orders of magnitude above ambient outdoor levels. Radon progeny attach easily to dust particles that can deposit in the lungs when inhaled. Once deposited in the lungs, the radon progeny emits alpha particles, mostly from short lived isotopes 218Po (T1/2 = 3.1 min, E = 6 MeV) and 214Po (T1/2=164.3 µs, E = 7.7 MeV), irradiating and damaging the DNA of lungs or proximal organ tissue, which may increase the risk of developing lung cancer - the second most common cause after smoking. Therefore monitoring radon levels in mines and caves is strictly required in order to protect workers from the health effects of radon exposure. Current radon detectors are bulky, expensive and only measure radon concentration, requiring conversion from concentration to dose which can result in large uncertainties [1]. This work presents a newly developed portable silicon on insulator (SOI) microdosimeter system for use in radon rich environments to measure the dose equivalent caused by 222Rn and its decay progeny. The microdosimeter used in this work is the Mushroom microdosimeters invented and developed by the CMRP, University of Wollongong and fabricated in collaboration with SINTEF MiNaLab, Oslo, Norway. The detector system directly measures in real time dose equivalent H(µSv/h) in a 222Rn gas environment rather than its calculation based on radon activity and dose conversion factor (DCF) as currently. The experiment was carried out at ANSTO environment lab where 245 kBq 226Ra source provides a radon concentration of approximately 150kBq/m3. A dose rate equivalent of 15.4 mSv/h and average quality factor ( ) of 19.96 was measured by the microdosimeter system for the given radon concentration. This result demonstrated that the microdosimeter system can be used in caves, mines for radon dose equivalent monitoring. Miniaturization of electronic personal microdosimeter is in progress and the preliminary results will be presented at the conference.

Description

In the item Scott Chambers is described as Scott Chamber (sic).

Keywords

Microdosimetry, Radon, Dosimetry, Mines, Caves, Trace amounts, Uranium, Actinium, Thorium, Neptunium, Ventilation, Dusts, Tobacco smokes, Lungs, Neoplasms, Occupational exposure, Occupational safety

Citation

Tran, L. T., James, B., Prokopovich, D. A., Boardman, D., Werczynski, S., Chamber (sic), S., Waring, C., Williams, A., Povoli, M., Kok, A., Jackson, M., & Rosenfeld, A. (2019). Solid-state microdosimeter for personal radon dosimetry in mines and caves. Poster presented to the Fifth International Symposium on the System of Radiological Protection, Adelaide, South Australia, 17-21 November 2019. Retrieved from: https://www.icrp.org/page.asp?id=457