An effort has been made to optimize the counting time for low-level measurement of naturally occurring radioactive material (NORM) by considering the standard deviation between the activity values of different photopeaks and counting error. It is observed that at lower counting time, relative standard deviation (RSD) varies randomly, but attains a gradual trend with increasing time and also comes closure to the counting error. Therefore minimum counting time for low-level NORM measurement of U-238 and Th-232 would be the time required to stabilize the RSD values.

PUNARBASU CHAUDHURI

Environmental Science

NABANITA NASKAR

SUSANTA LAHIRI

ALOK SRIVASTAVA

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

&nbsp;

The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

&nbsp;

It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Radioanalytical and Nuclear Chemistry

The present study evaluates the radiological indices due to naturally occurring radionuclides (238U, 232Th and 40K) present in surface soil samples of Indian Sundarbans. Univariate and multivariate statistical analysis were carried out to understand the probability distribution of the radionuclides, correlate and classify the different radiological parameters. Averages of absorbed dose rate (D), annual effective dose were found higher than world averages, whereas that of radium equivalent activity (Raeq), annual gonadal dose equivalent and hazard indices (Hin and Hex) were found below the maximum permissible limit. The data indicates that Indian Sundarbans poses no significant radiological health hazards. © 2019, Akadémiai Kiadó, Budapest, Hungary.

Estimation of radiological indices in Indian Sundarbans: a mangrove habitat

The present study attempts to quantitatively estimate total potassium content in soil samples collected from different areas of Indian Sundarbans by gamma-spectrometry, exploiting the radiogenic properties of potassium and by wavelength dispersive X-ray fluorescence technique. The elemental K concentration varied in between 2.08 ± 0.05 and 3.46 ± 0.06% in the soil samples. Besides estimation of total potassium, the activity of 40K was also estimated in the same soil samples and found to be in the range of 532 ± 8.9 to 1043 ± 13.2 Bq kg−1. © 2019, Akadémiai Kiadó, Budapest, Hungary.

Quantitative estimation of total potassium and 40 K in surface soil samples of Indian Sundarbans

Efficiency calibration by standard materials of known activity is usual protocol for γ-ray spectrometry. In general, 40K activity is measured from proper efficiency calibration covering broad energy range within which the 1460.83 keV photopeak falls. However, less frequently, the activity of 40K is reported by comparing the area under 1460.83 keV photopeak of natural sample to that of standard. The present study shows that determining the activity of 40K by efficiency calibration is highly dependent on the nature of fitting of calibration curve. The present paper also shows that comparator methods are more reliable for reporting 40K activity than efficiency calibration. © 2018, Akadémiai Kiadó, Budapest, Hungary.

Anomalies in quantitative measurement of 40K in natural samples

Measurement of naturally occurring radioactive material, U-238 and Th-232: part 2-optimization of counting time

A well-calibrated and highly shielded HPGe detector with considerable relative efficiency is an efficient tool for measurement of naturally occurring radioactive material (NORM) present at ultra low-level in the environmental samples. Efficiency calibration is standard protocol required for quantitative estimation of the activity of any radioactive sample. In the present work it has been shown that in the case of ultra-low level NORM measurement, one can comfortably by pass efficiency calibration by using comparator method i.e., comparing the peak area counts of different photopeaks of standard and samples provided they are counted in same geometry and comparable composition.

Measurement of naturally occurring radioactive materials, U-238 and Th-232-part 3: is efficiency calibration necessary for quantitative measurement of ultra-low level NORM?

This is the first attempt to generate baseline data on the level of Naturally Occurring Radioactive Materials, (NORMs) 238U, 232Th and anthropogenic radionuclide, 137Cs in surface soil of Indian Sundarban. The activities of 238U and 232Th vary from 39.9 ± 2.4 to 57.9 ± 2.5 Bq kg−1 and 47.3 ± 2.4 to 64.8 ± 3.1 Bq kg−1 with mean of 48.7 ± 2.8 Bq kg−1 and 58.3 ± 3.3 Bq kg−1 respectively. The corresponding median values are 46.7 and 59.9 Bq kg−1. The close proximity of mean and median values indicates normal distribution of 238U and 232Th. In most of the samples, anthropogenic 137Cs activity has been found below detection limit (BDL). © 2016, Akadémiai Kiadó, Budapest, Hungary.

Measurement of background radioactivity in surface soil of Indian Sundarban

There are more than 200 photopeaks of various daughter radionuclides of U-238 and Th-232 series, some of which have been randomly used for quantitative measurement of U/Th in natural samples. It has been observed that arbitrariness in photopeak selection may fail to stipulate statistically consistent data. This paper judiciously selects set of three photopeaks from each series whose respective averages could present statistically reliable measurement of U-238 and Th-232 based on minimum relative standard deviation (RSD) under the selected photopeaks. RSD is also proposed as an important parameter in NORM measurement.

Journal	Data powered by TypesetJournal of Radioanalytical and Nuclear Chemistry
Publisher	Data powered by TypesetSPRINGER
ISSN	0236-5731
Open Access	No