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   Table of Contents - Current issue
Coverpage
July-September 2018
Volume 41 | Issue 3
Page Nos. 107-161

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EDITORIAL  

Role of standards in radiation protection p. 107
MS Kulkarni
DOI:10.4103/rpe.RPE_75_18  
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ORIGINAL ARTICLES Top

Efficiency of high-purity germanium detector at characteristic gamma energies of 198Au and 58Co and covariance analysis Highly accessed article p. 110
Imran Pasha, B Rudraswamy, E Radha, V Sathiamoorthy
DOI:10.4103/rpe.RPE_38_18  
Naturally occurring 197Au and 58Ni foils were subjected to the neutron irradiation by placing them in a dry tube-I of Kalpakkam Mini reactor to produce gamma emitting 198Au and 58Co nuclear reaction products. The efficiency study of high-purity germanium detector corresponding to characteristic gamma energies 0.4118 and 0.8107 MeV of 198Au and 58Co was carried out by the methods of calibration of 152Eu and covariance.
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Assessment of annual effective dose due to outdoor radon activity in the environment of Bengaluru p. 115
MB Karthik Kumar, N Nagaiah, Gladys Mathews, MR Ambika
DOI:10.4103/rpe.RPE_40_18  
Soil is the major source of radon to enter the living environment. In the present study, an effort was made to see the contribution of radon activity to the dose received by the public of the study region. The radon activity in soil gas and radon exhalation rate from the surface soil were measured in the Bangalore University campus using a continuous radon monitoring device called RAD7. The value obtained in the present investigation is ranged from 1690 ± 362 to 7390 ± 324 Bq/m3, with the geometric mean (GM) of 4120 ± 307 Bq/m3, and 13.97 ± 7.55–24.82 ± 8.38 mBq/m2/s, with the GM of 18.13 ± 6.52 mBq/m2/s, respectively. The radon exhalation rate was also calculated using the values obtained from the radon activity in soil gas and is compared with the measured value. The annual effective dose (AED) was estimated from the measured radon concentration near to the soil surface and is found to be ranged from 0.02 to 0.07 mSv/y, with the GM of 0.04 mSv/y. The AED due to inhalation is well within the global average as reported in the UNSCEAR 2000, which indicates that there is no threat to the human due to the outdoor radon concentration in the study area.
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Seasonal variation of natural radioactivity in the environs of Kali River p. 119
KM Rajashekara, V Prakash, Y Narayana
DOI:10.4103/rpe.RPE_50_18  
The paper discusses the results of systematic studies of activity concentrations of the 226Ra, 232Th, and 40K in soil and sediment samples of Kali River, one of the major rivers of coastal Karnataka. The samples are collected in premonsoon, postmonsoon, and monsoon seasons; the activity concentrations of 226Ra, 232Th, and 40K in soil and sediment were measured by a NaI(Tl) gamma-ray spectrometer. The activity concentration of 226Ra is high in soil and sediment samples. The activity of 226Ra is almost constant, except one or two sampling stations of the rivers, and the activity of 232Th and 40K shows nonuniform distribution in soil and sediment samples of premonsoon and postmonsoon seasons. The results of these investigations are presented and discussed in this study.
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A study of energy absorption buildup factors of some steels p. 123
L Seenappa, HC Manjunatha, N Sowmya, KN Sridhar
DOI:10.4103/rpe.RPE_52_18  
We have studied the energy absorption buildup factors of some steels (316 LN, 317 L, 317 LM, 317 LMN, 317 LN, XM-14, XM-17, XM-18, and Nitronic 60) for wide energy range (0.015–15 MeV) up to the penetration depth of 40 mfp using geometric progression fitting method. Buildup factors increase with the increase in the penetration depth. It is found that the shielding parameters such as mass attenuation coefficient, effective atomic number, and buildup factor values are larger for steel type 316 LN than the other studied steels. Hence, the steel type 316 LN is a good shielding material among the studied steels. The present study is useful in the field of radiation shielding.
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Assessment of radioactivity level and radiological parameters in soil samples of Akalad, Thrissur District, Kerala p. 128
V Vineethkumar, V Prakash, Y Narayana
DOI:10.4103/rpe.RPE_45_18  
Systematic studies on radiation level and distribution of radionuclides have been carried out using NaI(Tl) detector in different locations of Akalad region, Thrissur District, Kerala. The activity of naturally occurring radionuclides viz. 40K, 226Ra and 232Th in the samples collected from the region were measured and found to vary in the range 9.99±0.69 Bq kg-1 to 32.11±0.77 Bq kg-1 with a mean value 19.64 Bq kg-1; 2.15±0.21Bq kg-1 to 11.28±0.39 Bq kg-1 with a mean value 7.73 Bq kg-1 and 20.80±0.67 Bq kg-1 to 122.40±1.16 Bq kg-1 with a mean value 79.91 Bq kg-1 respectively. The radium equivalent activity varies within the range 39.26 Bq kg-1 to 178.85 Bq kg-1 with a mean value 123.51 Bq kg-1. The absorbed dose rate varies within the range 16.49 nGyh-1 to 79.14 nGyh-1 with a mean value 51.91 nGyh-1. The present systematic investigation indicates that the data are comparable with the reported values elsewhere and in most of the cases observed values were well within the permissible limit.
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Measurement of radon concentration in drinking water and estimation of radiation dose to the publics of Hassan city, Karnataka, India p. 132
E Srinivasa, DR Rangaswamy, S Suresh, SR Nagabhushana, J Sannappa, K Umehsareddy
DOI:10.4103/rpe.RPE_46_18  
In the present paper, the radon concentration in drinking water samples of the Hassan city, Karnataka state, India, was analyzed using the radon emanometry technique. The measured radon concentrations ranged from 19.5 ± 1.5 to 121.8 ± 5.6 Bq/L with an average value of 61.4 ± 3.3 Bq/L. This study reveals that all the drinking water samples have radon concentration levels higher than the maximum contaminant level of 11 Bq/L as suggested by the Environmental Protection Agency, and 75% of the recorded radon concentration values were found to be well below the action level of 100 Bq/L recommended by the World Health Organization. The average annual effective dose to the population of the studied area was found to be slightly greater than the safe limit of 100 μSv/y recommended by the World Health Organization.
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Studies on ambient gamma dose rate and enrichment of radon, thoron, and progeny concentration in various types of dwellings and outdoor environments of Kalliasseri, Kannur district, Kerala p. 136
K Nadira Mahamood, V Prakash
DOI:10.4103/rpe.RPE_29_18  
The major contribution of natural background radiation exposure comes from radon, thoron, and their progeny. The activity concentration of these radionuclides depends on various factors, and the concentration level varies from place to place. The indoor concentration in dwellings depends mainly on the materials used for building construction and ventilation patterns. In the present study, an attempt is made to estimate the indoor and outdoor radon, thoron, and their progeny concentration in various types of dwellings and outdoor environments of Kalliasseri Panchayat, Kannur district, Kerala. 222Rn and 220Rn measurements were carried out using LR-115 type II-based pinhole cup dosimeters. Indoor and outdoor gamma exposure rate measurements were also carried out in all the dwellings using scintillation-based microradiation survey meter. The average concentrations of radon and thoron were estimated in about 40 dwellings categorized according to the construction type. The seasonal variation in the enrichment of radionuclides concentration has also been studied. The respective radon and thoron progeny levels were also estimated. The average radon concentration from the present study was well within the action level (200 Bq/m3) recommended by the International Commission of Radiological Protection (ICRP). The annual effective doses due to indoor radon and thoron were within the action level 3–10 mSv/y as suggested by the ICRP.
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Calculation of dose rates due to loss-of-coolant accident in open-pool spent-fuel storage p. 143
Amr Abdelhady
DOI:10.4103/rpe.RPE_31_18  
The objective of the spent-fuel storage pool is shielding the worker and public from radiation emitted by radioactive decay in the spent fuel and providing a barrier for any radioactive release. In open-pool multipurpose reactor, the spent-fuel storage pool is connected to the main pool through the transfer channel. It was prepared to store 528 spent-fuel elements distributed in two racks that constructed one above the other. The loss-of-coolant accident (LOCA) in spent-fuel storage pool could result in rising of the radiation dose in the reactor building as the water level in the pool falls. The value of the radiation dose rate depends on the height of the water level above the spent fuels, and the number of spent-fuel elements stored in the storage pool during LOCA. The dose rate calculations were carried out starting from the minimum height which the water level could drop above the spent-fuel storage racks. The calculations were carried for two cases as follows: the full capacity of both racks and the full capacity of the lower rack only. Monte Carlo N-Particle Transport MCNP5 code was used to calculate the radiation dose rate above the storage pool and in the control room. The results show that the dose rate in the control room would be lower than the permissible limit when the water level height was 270 and 140 cm for the two cases, respectively. The dose rate above the storage pool would be lower than the permissible limit when the water height above the racks is higher than 385 cm in the first case, and 290 cm for the second case.
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Determination of atmospheric concentration of beryllium-7 at ground level p. 148
Pablo A Andres
DOI:10.4103/rpe.RPE_35_18  
Atmospheric concentration of beryllium-7 (7Be) at ground level was measured from September 2012 to October 2013 in San Carlos de Bariloche, Argentina, using a HPV-5300AFC brushless, automatic flow control outdoor high volume air sampler for continuous use, and 8”×10” 0.8 microns fiberglass filters. The activity of 7Be was determined on a high-purity germanium (HPGe) detector (relative efficiency 12.3%) by standard gamma spectrometry. The average value found was 4.1 ± 0.1 mBq/m3. Seasonal changes in the atmospheric concentration of 7Be were compared with other environmental variables (temperature, humidity, precipitations, and air kerma rate), and correlation, both positive and negative, was observed as expected. Measurements were carried out following the Radiological Environmental Monitoring Programme at Bariloche Atomic Centre. The aim of the study was to determine atmospheric concentration of 7Be at ground level and to correlate its seasonal changes with environmental variables. Air samplers and environmental dosemeter locations were far away from buildings and any other thing that could influence or alter the measurements. Pearson's correlation coefficient was calculated to evaluate the relation between atmospheric 7Be concentration and environmental variables of interest. These changes in 7Be concentration can be attributed to the variations and dynamic of air exchange between the stratosphere and the troposphere and to the variations of the tropopause height. To fully understand and correctly interpret the meaning of these seasonal variations in the concentrations of atmospheric 7Be, active atmospheric processes must be taken into account. According to the measurements carried out, contribution of 7Be concentration to the natural background radiation dose is negligible.
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Enrichment pattern and depth profile of natural radionuclides in monazite areas of coastal Karnataka p. 152
V Prakash, K Nadira Mahamood, Y Narayana
DOI:10.4103/rpe.RPE_11_14  
The activities of radionuclides 232Th, 226Ra, and 40K have been measured in sand samples of Ullal beach area, where presence of low-level monazite has been reported. The sand samples collected from the region, at different distances from sea waterline and at different depths, were analyzed for radionuclide activity by gamma spectrometry to study the distribution, enrichment pattern, and vertical profile of the radionuclides in the region. The study on the enrichment of radionuclides in different size fractions shows highest activity confined in <125 μm and lowest activity confined in 1000–500 μm particle size fractions. The minimum 232Th activity was 1.1 Bq/kg, found in Ombattu Kere beach at a depth of 10–20 cm, at waterline in 1000–500 μm particle size fraction and maximum activity of 6690.7 Bq/kg was found in Ombattu Kere beach at a depth of 10–20 cm, at 50 m away from waterline in grains of size 250–125 μm. The lowest 226Ra activity was 25.1 Bq/kg, found in Ombattu Kere beach at a depth of 10–20 cm, at waterline in grains of size 1000–500 μm and highest 226Ra activity was 1286.0 Bq/kg, found in Ombattu Kere beach in grains of size <125 μm for sample collected at a distance of 50 m away from waterline and at a depth of 10–20 cm. The minimum 40K activity was 130.5 Bq/kg, found in Ombattu Kere beach at a depth of 20–30 cm, at 50 m away from waterline in grains of size 500–250 μm and maximum activity of 40K was 5686.2 Bq/kg, found in Ombattu Kere beach for sample collected at waterline at a depth of 20–30 cm in <125 μm particle size fraction. The dose rate measured using plastic scintillometer at 1 m above the ground level at Ullal is having the range 39.4–459.9 nGy/h with a mean value of 193.2 nGy/h. The results of these investigations are presented and discussed in this article.
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NEWS AND INFORMATION Top

Excerpts of UNSCEAR white paper on “evaluation of data on thyroid cancer in regions affected by the Chernobyl accident” p. 160
DD Rao
DOI:10.4103/rpe.RPE_72_18  
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