Mapping of the geogenic radon potential in France to improve radon risk management: methodology and first application to region Bourgogne

Soil gas (222Rn, CO2, 4He) behaviour over a natural CO2 accumulation, Montmiral area (Drôme, France): geographical, geological and temporal relationships

“…Moreover contents were compatible with the bibliographic data for such formations (Schumann and Gundersen, 1996), the levels the richest in clays (MO62; Fig. 5b) had the highest U and Th concentrations, by effect of concentration of these elements in the argillaceous phases and/or in the ferrous hydroxides and unlike the low content of carbonated sedimentary elements (Ielsch et al, 2010). As for the CO 2 phase, a good correspondence existed with the 222 Rn concentrations measured in these soils.…”

“…From the grain size distribution, from which the soil permeability is dependent, it appeared that coarse soils favoured the existence of high CO 2 concentrations (MO61) and that fine grained, clay-rich soils had much lower amounts (MO63). The 222 Rn concentrations also depended from grain size distribution and consequently from soil permeability (Ielsch et al, 2010) as will be debated later on. The 238 U content is another limiting factor that directly controls 222 Rn existence through many processes (Navas et al, 2002).…”

Radon in Air and Water

“…However, natural cavities such as potholes and swallow holes in limestone would also be difficult to locate precisely due to their irregular and relatively unpredictable disposition. Radon has been used to identify the location of faults and frequently reaches a maximum in the direct vicinity of faults (Barnet et al, 2008;Ielsch et al, 2010;Neri et al, 2011;Pereira et al, 2010;Swakon et al, 2005). However, a consistent decrease of indoor radon away from mapped faults is not observed in the UK (Appleton, 2004) and it is likely that elevated radon concentrations will be associated mainly with active faults.…”

“…This initial map is enhanced by overlaying parameters, such as fault lines, which control the preferential pathways of radon through the ground and which can increase the radon levels in soils. The geogenic radon map provides a more precise zoning than the scale of the map of radon priority areas currently based solely on administrative boundaries (Ielsch et al, 2010).…”

Towards a european atlas of natural radiation: Goal, status and future perspectives

“…This approach is widely used; e.g. Germany [11], Czech Republic [10], France [12], USA [13]. Uncertainty can be included by generating "uncertainty classes", as demonstrated in the US radon map [13].…”