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Study of radon flux and natural radionuclides (226Ra, 232Th and 40K) in the Main Boundary Thrust region of Garhwal Himalaya

Kandari T., Prasad M., Pant P., Semwal P., Bourai A. A., Ramola R. C.

Acta Geophysica

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2018

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Vol. 66, no. 5

1243--1248

EN

The Himalayan region is subdivided lithologically into four regions in which the junction between the lower Himalaya and Shivalik is known as the Main Boundary Thrust (MBT). It is well known that the environmental radon concentration depends upon various geological factors including faults, thrust, cracks and the composition of the soil. Radon gas eventually comes out from the fault/thrust zones having radium as its prominent source. Hence, it is important to study the behaviour of emission of radon present inside the earth crust as well as the levels of natural radionuclides in soil. In this study, the levels of natural radionuclides and exhalation rates of radon in the soil of MBT region of Garhwal Himalaya, India, were determined by using gamma ray spectrometer and scintillation detector-based Smart Radon Monitor, respectively. The average activities of 226Ra, 232Th and 40K were found 71.9, 88.2 and 893.6 Bq Kg-1, respectively. The measured radon surface flux was found to vary from 13.08 to 1626.4 Bq m-2 h-1 with a mean value of 256.5 Bq m-2 h-1. The measured activity levels were used to assess the doses associated with the contaminated soil.

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Measurement of 222Rn and 220Rn exhalation rate from soil samples of Kumaun Hills, India

Semwal P., Singh K., Agarwal T. K., Joshi M., Pant P., Kandari T., Ramola R. C.

Acta Geophysica

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2018

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Vol. 66, no. 5

1203--1211

EN

The source terms, i.e., exhalation and emanation from soil and building materials are the primary contributors to the radon ( 222Rn)/thoron ( 220Rn) concentration levels in the dwellings, while the ecological constraints like ventilation rate, temperature, pressure, humidity, etc., are the influencing factors. The present study is focused on Almora District of Kumaun, located in Himalayan belt of Uttarakhand, India. For the measurement of 222Rn and 220Rn exhalation rates, 24 soil samples were collected from different locations. Gamma radiation level was measured at each of these locations. Chamber technique associated with Smart Rn Duo portable monitor was employed for the estimation of 222Rn and 220Rn exhalation rates. Radionuclides ( 226Ra, 232Th and 40K) concentrations were also measured in soil samples using NaI(Tl) scintillation based gamma ray spectrometry. The mass exhalation rate for 222Rn was varying between 16 and 54 mBq/kg/h, while the 220Rn surface exhalation rate was in the range of 0.65–6.43 Bq/m2/s. Measured gamma dose rate for the same region varied from 0.10 to 0.31 µSv/h. Inter-correlation of exhalation rates and intra-correlation with background gamma levels were studied.

3

Continuous measurement of equilibrium equivalent radon/thoron concentration using time-integrated flow-mode grab sampler

Pant P., Kandari T., Prasad M., Semwal P., Ramola R. C.

Acta Geophysica

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2018

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Vol. 66, no. 5

1267--1272

EN

The continuous measurement of any physical entity is the finest approach to see the real-time variation of any concentration. In the present study, an effort has been made to see the continuous variation of radon and thoron progeny concentration (EERC and EETC) using time-integrated flow-mode sampler in which the deposition of progeny particles has been done in the filter paper in which an absorber has been mounted which specifically absorbs the alpha energies emitted by the progenies of radon or thoron. Also, the variation of thoron progeny concentration (EETC) using two different types of SSNTDs, LR-115 and CR-39, has been seen and it has been found that the measurement of EETC using both of the detectors is very much comparable with positive relationship (R = 0.89) between the results obtained.