Indoor and outdoor radon survey in Slovenia by etched track detectors

The equipment and method for large scale radon monitoring utilizing etched track detectors developed in our laboratory is reviewed. This review comprises a description of: (i) two high sensitive (approx. 1 and approx. 10 kBq m-3h) radon dosemeters, (ii) devices for chemical and electrochemical etching and (iii) a microcomputer assisted system for counting nuclear tracks. This is followed by a brief summary of indoor radon distribution measurements in some regions of Slovenia (two biggest towns, an area with high natural radioactivity, an area in the vicinity of coal fired power plant) and outdoor radon monitoring in the vicinity of the uranium mine Zirovski vrh. Results obtained from 326 dwellings show that the median value of radon concentration in Slovenian homes is approx. 70 Bq/m3. A median value of radon concentration in 25 years old houses in Poljanska Valley, characterized by high natural radioactivity, was found to be approx. 230 Bq/m3. The annual outdoor average radon concentration in the surrounding villages of uranium mine Zirovski vrh was found to be approx. 20 Bq/m3. The outdoor radon concentration in other regions of Slovenia is from 5 to 20 Bq/m3 depending on microclimatic and geological conditions. (author). 19 refs, 6 figs, 3 tabs