RADON LEVELS IN OUTDOOR AIR AND SOIL GAS

RELATED TO GEOLOGY OF SLOVENIA

A. Gregorič1, P. Žvab2, J. Vaupotič1, J. Mazur3, K. Kozak3

1Jožef Stefan Institute, Department of Environmental Sciences, Radon Center, Ljubljana, Slovenia

2University of Ljubljana, Faculty of Natural Sciences and Engineering, Ljubljana, Slovenia

3 H k Ni d i ń ki N l Ph i I tit t3 Henryk Niewodniczański Nuclear Physics Institute, Polish Academy of Sciences, Kraków, Poland

RadiationRadiation protectionprotectionRadiationRadiation protectionprotection

Two main directions of radon investigations in Slovenia

Radon in living and working environment Concentrations of radon and its short lived decay products

Radon in living and working environment Concentrations of radon and its short lived decay products

Radiation Radiation protectionprotectionRadiation Radiation protectionprotection

Concentrations of radon and its short lived decay productsin the attached and unattached form, equilibrium factor,non-radioactive aerosols, meteorological conditions (T, P, RH),identification of radon sources, mitigations, radon mapping

Concentrations of radon and its short lived decay productsin the attached and unattached form, equilibrium factor,non-radioactive aerosols, meteorological conditions (T, P, RH),identification of radon sources, mitigations, radon mapping, g , pp g

Radon dosimetryOptimization of methodology for dose calculations

, g , pp gRadon dosimetry

Optimization of methodology for dose calculations

RadRadon transporton transportRadRadon transporton transportRadon anomalies in soil gas and thermal water related toRadon anomalies in soil gas and thermal water related toearthquakes and activity of tectonic faults

Continuous monitoring of radon in soil gas and thermal waterSpatial and temporal variations of Rn in soil gasLo le el radon areas

earthquakes and activity of tectonic faultsContinuous monitoring of radon in soil gas and thermal water

Spatial and temporal variations of Rn in soil gasLo le el radon areasLow level radon areas

Radon measurements in outdoor air and in seawater profilesLow level radon areas

Radon measurements in outdoor air and in seawater profiles2/12

Radon measurements in outdoor air and in soil gas

Outdoor airOutdoor air60 measurement points have been selected over the entire60 measurement points have been selected over the entire60 measurement points have been selected over the entire

country (mostly at the meteorological stations within the nationalnetwork) where long-term permanent national radioactivity

60 measurement points have been selected over the entirecountry (mostly at the meteorological stations within the nationalnetwork) where long-term permanent national radioactivitymonitoring (gamma dose rate with thermoluminescentdosimeters) is being carried out

in nearby dwellings radon concentration in indoor air at the

monitoring (gamma dose rate with thermoluminescentdosimeters) is being carried out

in nearby dwellings radon concentration in indoor air at they gsame 60 points was measured

y gsame 60 points was measured

S ilS ilSoil gasSoil gas

at the same 60 measurement pointsat the same 60 measurement pointsadditional 72 measuring points on radon risk areasadditional 72 measuring points on radon risk areas

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Radon measurements in outdoor air

Nuclear track detectors based on a CR-39 foil (Radonlab, Norway)were exposed in pairs for 3−5 months in Summer 2005 andSpring – Summer 2007.p g

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Radon measurements in soil gas

Nuclear track detectors (Radonlab, Norway) were exposed in pairsfor 4−7 days in August 2007 and Nuclear track detectors (IFJ-PAN,y g ( ,Kraków, Poland) for 2−3 weeks in August 2008.

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Lithology map of Slovenia with measurement pointsmeasurement points

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Lognormal distribution of radon concentration in outdoor air and in soil gasoutdoor air and in soil gas

GM=20.7 kBq m–3

GM=10.0 Bq m–3

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Box & whisker plots of radon concentrations

outdoor air soil gas

Lithological units: A – carbonates, B – clastic sediments, C – clay-gravel deposits D gravel deposits and E Tertiary sediments

lithological unit lithological unit

gravel deposits, D – gravel deposits and E – Tertiary sediments

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Correlation between radon concentration in outdoor air and in soil gasin outdoor air and in soil gas

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R d

Kindergartens and schools

Radon maps

km

Koncentracije radona v zunanjem zraku

Soil gasOutdoor air

0 15 30 45 60

kBq m-3 45

50

CRn

(Bq m−3)

kBq m-3

30

40

80

200

kBq m

30

40

80

200

20

25

30

35

40

0

5

10

20

10/120

5

10

20

5

10

15

0 15 30 45 60

km

Radon in soil gas: correlations

y = 0.454xr = 0.79

100

150

/ Bq

m–3

y = 1.6568xr = 0.86

150

200

250

300

kBq

m–3

0

50

0 50 100 150 200 250 300 350

CR

n/

0

50

100

150

AG

/ k

y = 3 4107x1200

y = 1 5577x1200

0 50 100 150 200 250 300 350

C Ra / Bq kg–1

00 20 40 60 80 100 120

ETD / kBq m–3

y = 3.4107xr = 0.220

400

600

800

1000

n/ B

q m–2

s–1m

–3...

. y = 1.5577xr = 0.224

400

600

800

1000

n/ B

q m–2

s–1m

–3

0

200

0 20 40 60 80 100 120

C Rn / Bq m–3

E Rn

0

200

0 50 100 150 200 250 300 350

C Ra / Bq kg–1

E Rn

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C Rn / Bq m C Ra / Bq kg

CONCLUSIONSCONCLUSIONSCONCLUSIONSCONCLUSIONS

The widest ranges and highest radon concentrations in bothg goutdoor air and soil gas have been found on carbonates in westernand southern part of the country.

Elevated values in outdoor air and soil gas have been also foundin close proximity to the tectonic faults.

A moderate correlation between radon concentration in outdoorair and soil gas has been observed.

In order to upgrade the preliminary map of radon in soil gas, amore dense grid of measurement points should be used – which willpresumably be done in the future

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presumably be done in the future.