Radon exhalation rate measurements on and around the premises of a former coal mine

The article presents a part of the measurements around a closed coal mine in an area of 2 km2 where newbuildings are planned. Because of high content of natural radioactivity (U and 226Ra) in coal and fly ash inthis area, high radon concentrations were measured. Monitoring consists of measurements on the coal minerepository and around it. Values of radon exhalation rates were in the range from 9 x 10-3 to 4 x 10-1 Bqm-2s-1. On the areas rich with coal and coal ash, higher radon exhalation rates were determined during allperiods of the year. One location in the coal mine area was covered with soil and clay which decreasedradon exhalation rates by one order of magnitude. Radon exhalation rates measured on populated area arealso high because coal fly ash has been used for covering ground around buildings. The results of thisinvestigation will be useful for predicting the type of construction in case of new building on the area ofa closed mine.