Journal of Basic and Applied Sciences  -   Volume 8 Number 2

Measurement of Annual Effective Doses of Radon from Drinking Water and Dwellings by CR-39 Track Detectors in Kulachi City of Pakistan

Tabassum Nasir and Mujtaba Shah

http://dx.doi.org/10.6000/1927-5129.2012.08.02.44

Abstract: Radon concentration and annual effective doses were measured in drinking water and dwellings of Kulachi city of Pakistan. Twenty samples of drinking water were collected from various sources i.e. tap water, pond water, hand pump and tube well water. CR-39 (Columbia Resin-39) based NRPB (National Radiological Protection Board) radon dosimeters were used to measure the radon concentration. Among the various types of samples, the maximum average value of radon concentration was detected (1.218±0.005 Bq/L) in tube well water while the minimum average value was (0.602±0.003 Bq/L) in tap water. The annual effective dose was calculated from the measured radon concentration which varied from 4.39 × 10-3 to 8.89 × 10-3 mSv/y. The measured values of radon concentration as well as the annual effective dose were found within the United States Environmental Protection Agency (US-EPA) and World Health Organization (WHO) recommended limits.

In order to carry out radon survey in dwelling, thirty CR-39 based NRPB dosimeters were installed in various buildings in the area under study. The maximum measured indoor radon concentration was found to be 270±22 Bq/m3 while the minimum was 21±2 Bq/ m3. The mean value of indoor radon concentration in bed rooms was 98 Bq/m3 which was within the International Commission on Radiological Protection (ICRP) recommended limits however, maximum concentration of 240 Bq/m3 was observed in a mud made room which was above the US-EPA and WHO new recommended limits. The mean annual effective dose from indoor radon was found to be 1.546 mSv/y which was within the ICRP recommended limits.

Keywords: Drinking water, Dwellings, CR-39, NRPB dosimeters, Radon concentration, Annual effective dose.

 

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The Effect of Grain Size on Radon Exhalation Rate in Soil Samples of Dera Ismail Khan in Pakistan

Tabassum Nasir and Nisar Ahmad

http://dx.doi.org/10.6000/1927-5129.2012.08.02.29

Abstract: Radon concentration and its exhalation rate has been measured from twenty five soil samples collected from seven different locations of Dera Ismail Khan, in the north west of Pakistan. These samples were crushed after drying and passed through sieves with different sizes of pores to get three grain sizes, £0.595 mm, 0.595-2.00 mm and 2.00-4.00 mm of soil. CR-39 based NRPB (National Radiological Protection Board) radon dosimeters have been used to measure the radon concentration and exhalation rates. The maximum average value of radon exhalation rate has found to be: (3.57±0.38) Bq m-2 hr-1 in the samples having grain size 2.00-4.00 mm and the minimum as: (2.21±0.26) Bq m-2 hr-1, in the samples with grain size £ 0.0595 mm. This indicates that the radon exhalation rate increases with the grain size. The maximum average value of radon exhalation rate has been found in samples collected from river side where soil texture is silty clay loam. The obtained values of radon exhalation rate for all the samples are well below the world average value of 57.60 Bq m-2 hr-1.

Keywords: Radon concentration, Radon exhalation rate, grain size, soil texture.

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