A home-made, low cost, high speed, etched track detector measuring system, equipped with automatic track counting and classification procedures, was developed to measure and analyse quickly and ...accurately CR-39 etched track detectors used in indoor radon concentration surveys. The system provides increased detector throughput along with high measuring accuracy and it can therefore serve as a platform for the large scale measurements of the Greek National Radon Survey that will take place in the near future. In this context, pilot measurements of indoor radiation were performed in selected Greek regions. Indoor radon concentrations were found in the range of 4 to 583 Bq.m-3 with the highest levels observed near the water springs of Ikaria island. The indoor absorbed dose rate in air due to external irradiation from terrestrial sources was measured simultaneously, using thermoluminescence dosemeters (LiF TLD-100), and was found to be in the range of 19 to 107 nGy.h-1 with an arithmetic mean value equal to 49 ± 22 (1s) nGy.h-1, in good agreement with our previous study.
