Seasonal variation of radon in the Bozkov Cave

Measurement of the radon concentration has been performed in the Bozkov dolomite cave since 2002. Radon concentration was obtained by two means: continuous measurement by a Radim3 monitor at 30 min intervals and a 6 month average by LR115 solid-state nuclear track detector (SSNTD) in a diffusion chamber placed at 8 points along the cave tour path. The radon concentration shows diurnal, seasonal, and yearly variations. The concentration maximum in the cave, in contrast to the dwellings, occurs in the summer time and equals to thousands of Bq/m3. At the same time, high variability of radon concentration occurs. Statistical analysis of a long time series of radon concentration was performed and the meteorological data were taken into account. The annual effective dose from radon for the cave guide (2006 y, working time spent in the cave 414 h) was 3.05 mSv. The dose was calculated using the mean value of radon concentration obtained by SSNTD as written above. (authors)