Abstract
A countrywide survey on radon and thoron levels has been carried out in Indian dwellings under a Coordinated Research Project sponsored by the Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy (DAE). Eight universities and a few research institutions from different parts of the country participated in this project. Under this project, radon and thoron levels were measured using Solid State Nuclear Track Detector (SSNTD) -spark counter based passive technique. A plastic twin chamber radon -thoron dosimeter was developed and standardized for the survey. This radon-thoron discriminating dosimeter uses three SSNTDs; two of which are exposed in cup modes and the third one is exposed in bare mode. Calibration factors (CF) are obtained for cup and bare mode SSNTDs through controlled experiments in a calibration facility. Calibration factors obtained from experiments showed very good agreement with the calibration factors derived from theoretical models. Four nodal centres were set up each at Kalpakkam, Jodhpur, Jaduguda and Mumbai for calibration and standardization of the dosimeter system. Inter calibration of the dosimeters were also carried out for comparison purpose. Nearly 4500 measurements in about 1400 dwellings were made during the survey period. An analysis of the data shows that the
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Ramachandran, T V;
Eappen, K P;
Nair, R N;
Mayya, Y S;
Sadasivan, S
[1]
- Environmental Assessment Div., Bhabha Atomic Research Centre, Mumbai (India)
Citation Formats
Ramachandran, T V, Eappen, K P, Nair, R N, Mayya, Y S, and Sadasivan, S.
Radon-thoron levels and inhalation dose distribution patterns in India dwellings.
India: N. p.,
2003.
Web.
Ramachandran, T V, Eappen, K P, Nair, R N, Mayya, Y S, & Sadasivan, S.
Radon-thoron levels and inhalation dose distribution patterns in India dwellings.
India.
Ramachandran, T V, Eappen, K P, Nair, R N, Mayya, Y S, and Sadasivan, S.
2003.
"Radon-thoron levels and inhalation dose distribution patterns in India dwellings."
India.
@misc{etde_20567267,
title = {Radon-thoron levels and inhalation dose distribution patterns in India dwellings}
author = {Ramachandran, T V, Eappen, K P, Nair, R N, Mayya, Y S, and Sadasivan, S}
abstractNote = {A countrywide survey on radon and thoron levels has been carried out in Indian dwellings under a Coordinated Research Project sponsored by the Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy (DAE). Eight universities and a few research institutions from different parts of the country participated in this project. Under this project, radon and thoron levels were measured using Solid State Nuclear Track Detector (SSNTD) -spark counter based passive technique. A plastic twin chamber radon -thoron dosimeter was developed and standardized for the survey. This radon-thoron discriminating dosimeter uses three SSNTDs; two of which are exposed in cup modes and the third one is exposed in bare mode. Calibration factors (CF) are obtained for cup and bare mode SSNTDs through controlled experiments in a calibration facility. Calibration factors obtained from experiments showed very good agreement with the calibration factors derived from theoretical models. Four nodal centres were set up each at Kalpakkam, Jodhpur, Jaduguda and Mumbai for calibration and standardization of the dosimeter system. Inter calibration of the dosimeters were also carried out for comparison purpose. Nearly 4500 measurements in about 1400 dwellings were made during the survey period. An analysis of the data shows that the indoor radon gas concentrations at different locations vary between 4.6 and 147.0 Bq.m{sup -3} with a geometric mean of 23.0 Bq.m{sup -3} (GSD 2.61). Indoor thoron gas concentrations, in general, are found to be less than the radon concentrations and vary from 3.6 to 42.8 Bq.m{sup -3} with a geometric mean of 12.2 Bq.m{sup -3} (GSD 3.22). The mean annual inhalation dose rate due to radon, thoron and their progeny in the dwellings is estimated to be 0.97 mSv.y{sup -1} (GSD 2.49). It is observed that the major contribution to the indoor inhalation dose is due to radon and its progeny. However, the contribution due to thoron and its progeny is not trivial as it is about 20 % of the total indoor inhalation dose rates. High indoor inhalation dose rates are observed at the northeastern region of India. The contribution due to thoron and its progeny in these regions is found to be nearly 30 % of the total inhalation dose. The dependence of indoor radon levels on the dwelling types, examined statistically, has indicated significant differences between mosaic and wooden floors having plastered and whitewashed walls. A radon/ thoron atlas of the country has been prepared using the data generated not only from from this project but also from earlier surveys carried out by this Centre. (author)}
place = {India}
year = {2003}
month = {Sep}
}
title = {Radon-thoron levels and inhalation dose distribution patterns in India dwellings}
author = {Ramachandran, T V, Eappen, K P, Nair, R N, Mayya, Y S, and Sadasivan, S}
abstractNote = {A countrywide survey on radon and thoron levels has been carried out in Indian dwellings under a Coordinated Research Project sponsored by the Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy (DAE). Eight universities and a few research institutions from different parts of the country participated in this project. Under this project, radon and thoron levels were measured using Solid State Nuclear Track Detector (SSNTD) -spark counter based passive technique. A plastic twin chamber radon -thoron dosimeter was developed and standardized for the survey. This radon-thoron discriminating dosimeter uses three SSNTDs; two of which are exposed in cup modes and the third one is exposed in bare mode. Calibration factors (CF) are obtained for cup and bare mode SSNTDs through controlled experiments in a calibration facility. Calibration factors obtained from experiments showed very good agreement with the calibration factors derived from theoretical models. Four nodal centres were set up each at Kalpakkam, Jodhpur, Jaduguda and Mumbai for calibration and standardization of the dosimeter system. Inter calibration of the dosimeters were also carried out for comparison purpose. Nearly 4500 measurements in about 1400 dwellings were made during the survey period. An analysis of the data shows that the indoor radon gas concentrations at different locations vary between 4.6 and 147.0 Bq.m{sup -3} with a geometric mean of 23.0 Bq.m{sup -3} (GSD 2.61). Indoor thoron gas concentrations, in general, are found to be less than the radon concentrations and vary from 3.6 to 42.8 Bq.m{sup -3} with a geometric mean of 12.2 Bq.m{sup -3} (GSD 3.22). The mean annual inhalation dose rate due to radon, thoron and their progeny in the dwellings is estimated to be 0.97 mSv.y{sup -1} (GSD 2.49). It is observed that the major contribution to the indoor inhalation dose is due to radon and its progeny. However, the contribution due to thoron and its progeny is not trivial as it is about 20 % of the total indoor inhalation dose rates. High indoor inhalation dose rates are observed at the northeastern region of India. The contribution due to thoron and its progeny in these regions is found to be nearly 30 % of the total inhalation dose. The dependence of indoor radon levels on the dwelling types, examined statistically, has indicated significant differences between mosaic and wooden floors having plastered and whitewashed walls. A radon/ thoron atlas of the country has been prepared using the data generated not only from from this project but also from earlier surveys carried out by this Centre. (author)}
place = {India}
year = {2003}
month = {Sep}
}