Éva Hedvig NAGY^a,b,*, Dániel BREITNER^a,c, Ákos HORVÁTH^b, Csaba SZABÓ^a
aLithosphere Fluid Research Lab, Department of Petrology and Geochemistry, Eötvös University, Pázmány P. s. 1/c, 1117, Budapest, Hungary, ^*jadzsa@gmail.com
^bDepartment of Atomic Physics, Eötvös University, Pázmány P. s. 1/a, 1117, Budapest, Hungary
^cKFKI Atomic Energy Research Institute, Hungarian Academy of Sciences, Konkoly Thege út 29-33, 1121, Budapest, Hungary

STUDY OF A PASSIVE RADON MITIGATION PROCESS AND INDOOR RADON CONCENTRATION’S TIME DEPENDENCE AFTER MITIGATION

Full text

The uranium mining was stopped in the Mecsek Mountains (S-Hungary) in 1997 and mine reclamation of the contaminated area began. For this purpose radiometric survey of houses in the towns of the former mining area, including settlement of Kővágószőlős, was undertaken. Long-term indoor radon monitoring by using etched track detector in dwellings was a part of the radiometric survey. Most of the dwelling houses, located close to a mine-tunnel, show a yearly average of indoor radon activity concentration higher than the EU recommendation for existing buildings (400 Bq/m³). A typical two story brick house was selected to test a mitigation method. The house cellar showed 1950 Bq/m³ on average of indoor radon activity concentration during the summer of 2004 (03.06.2004-30.08.2004), and in the bedroom above the cellar 450 Bq/m³ (by etch track detectors). To reduce this high radon concentration, a new radon mitigation was completed in the house. Before mitigation, the soil radon characteristics were determined around the house, which shed light on high radon exhalation values (range 20-200 mBq/m²s, average: 100 mBq/m²s) and significant radium content (60-65 Bq/kg). Indoor radon concentration (averaged for 1 hour) was also monitored continuously for one month once before and three times after the mitigation technique was applied. Due to the mitigation, the initial radon concentration was decreased by 71% (average radon concentration in the same period of the year before the mitigation: 1480±74 Bq/m³, after the mitigation: 420±33 Bq/m³). Time dependence of radon concentration after the mitigation shows characteristic features due to the change in meteorological conditions, such as variations in temperatures. Daily dependence of the radon concentration is clearly showed by high radon activity values which occurred a few times in the afternoon governed by temperature change. High values these peaks result in a relatively high average radon level (1480±74 Bq/m³). However, the radon concentration at nights is always significantly lower than the average.