Abstract

• Determination of radon in basement of building was carried out by using LR 115 Type II solid state nuclear track detector with exposure period of 100 days during rainy season, winter and summer. The detectors were placed about 2.4 m from the floor at the five concrete tiles in the basement of selected building. After exposure, the detectors were etched in a NaOH solution of 2.5 N at temperature of 60°C for 90 min. Optical microscope NIKON ECLIPSE 50i was used to count the number of tracks on the detector. It was observed that track density of samples ranged from 7.80 ± 0.49 to 16.51 ± 0.91 C/cm2 day-1 in rainy reason, 5.48 ± 0.33 to 8.79 ± 0.54 C/cm2 day-1 in winter and 6.88 ± 0.41 to 14.73 ± 0.74 C/cm2 day-1 in summer. Radon concentration values were found to vary from 155 ± 9.73 to 329 ± 18.14 Bqm-3 with a mean value of 239.4 ± 12.35 Bqm-3 in rainy season, 109 ± 6.51 to 175 ± 10.71 Bqm-3 with a mean value of 139.6 ± 8.79 Bqm-3 in winter and 137 ± 8.25 to 294 ± 14.72 Bqm-3 with a mean value of 181.80 ± 10.60 Bqm-3 in summer. The overall radon concentration varied from 109 ± 6.51 to 329 ± 18.14 Bqm-3 with an average of 186.80 ± 10.58 Bqm-3 and the annual effective dose varied from 1.88 ± 0.11 to 5.66 ± 0.31 mSv/yr with the average value of 3.22 ± 0.18 mSv/yr in basement of selected tower for rainy season, winter and summer. The value of radon concentration and the annual effective dose in basement of selected building for rainy season, winter and summer were within the reference levels (200–600 Bqm-3 and 3–10 mSv/y) of International Commission of Radiological Protection (ICRP).