Radon Levels in Abandoned Metalliferous Mines, Devon, Southwest England

Short-term <sup>222</sup>Rn activity concentration changes in underground spaces with limited air exchange with the atmosphere

“…with its radioactive daughters, is responsible for about 40−50% of (1 -2.5 mSv/year) which a typical person receives from all natural sources of ionising radiation within a year (Commission 1990;UNSCEAR, 2000;Waligórski, 2010 Przylibski and Fijałkowska-Lichwa, 2010;Gillmore et al, 2001Gillmore et al, , 2002Chibowski and Komosa, 2001;Kullab et al, 2001;Kávási et al, 2003;Papachristodoulou et al, 2004;Perrier et al, 2004a, b;Olszewski et al, 2005;Lario et al, 2005Lario et al, , 2006Gervino et al, 2007;Lu et al, 2009;. Their findings have turned out to be comparable, and the most recent studies only extend the previously known regularities to next underground spaces.…”

Environmental radioactivity in the UK: the airborne geophysical view of dose rate estimates

“…Former mine plans indicate Ochre works and dressing floors north of the main adit (arrowed). Radon levels in the mine are known to be hazardous from studies described by Gillmore et al (2001) who also give a historical account of metalliferous workings at the site. Gillmore et al (2001) note that even standing 2 m outside the mine entrance, radon gas levels of >7,600 Bq.m -3 may be recorded (values are variable and seasonal).…”

Radon in Air and Water

“…A number of occupations have the potential for high exposure to 222 Rn progeny: mine workers, including uranium, hard rock, and vanadium; workers remediating radioactive contaminated sites, including uranium mill sites and mill tailings; workers at underground nuclear waste repositories; radon mitigation contractors and testers; employees and recreational visitors of natural caves (Gillmore et al, 2002;Gillmore et al, 2000); phosphate fertilizer plant workers; oil refinery workers; utility tunnel workers; subway tunnel workers; construction excavators; power plant workers, including geothermal power and coal; employees of radon health mines; employees of radon balneotherapy spas (waterborne 222 Rn source); workers and visitors to hot spring hotels (Song et al, 2011); water plant operators (waterborne 222 Rn source); fish hatchery attendants (waterborne 222 Rn source); employees who come in contact with technologically enhanced sources of naturally occurring radioactive materials; and incidental exposure in almost any occupation from local geologic 222 Rn sources. Recreational and other visitors to abandoned metalliferous mines may also be exposed to high radon concentrations (Gillmore et al, 2001). …”

“…Earlier isotopes mostly have long half-lives, while the later isotopes, including radon ( 222 Rn), have relatively short half-lives. Outdoors, radon normally disperses in the air whereas in confined spaces such as buildings, mines, and caves (Gillmore et al, 2001;Gillmore et al, 2002;Gillmore et al, 2000) it may accumulate. Higher radon (average 480 Bq m -3 ) was found in houses located ±150m from the surface projection of a closed uranium mine tunnel in Hungary compared with houses located further away (average 291 Bq m -3 (Somlai et al, 2006).…”

“…Radon has also been used for earthquake and vulcanological investigations (Avino et al, 1999;Ciotoli et al, 1998;Ghosh et al, 2009;Hishinuma et al, 1999;Papastefanou, 2010) Artificial pathways underground include mine workings and disused tunnels and shafts. Radon concentrations in old uranium and other mine workings are commonly 10,000-60,000Bq m -3 and can be as high as 7,100,000Bq m -3 even when uranium is a very minor component of the metalliferous veins (Gilmore et al, 2001). High radon is known to be associated with gassy ground overlying coal-bearing rock strata.…”