|Year : 2021 | Volume
| Issue : 1 | Page : 12-18
Studies on natural and fallout radioactivity mapping of the proposed Mithivirdi Atomic Power Project Site in Bhavnagar District, Gujarat, India
Akhaya Kumar Patra1, TJ Jaison1, SS Wagh1, MK Jha1, IV Saradhi2, A Vinod Kumar2
1 Environmental Survey Laboratory (Environmental Studies Section, Environmental Monitoring and Assessment Division, Bhabha Atomic Research Centre), Surat, Gujarat, India
2 Environmental Monitoring and Assessment Division, BARC, Mumbai, Maharashtra, India
|Date of Submission||26-Feb-2021|
|Date of Decision||16-Mar-2021|
|Date of Acceptance||08-Apr-2021|
|Date of Web Publication||07-Jun-2021|
Akhaya Kumar Patra
Environmental Survey Laboratory (ESS, EMAD, BARC), Kakrapar Gujarat Site, P.O. Anumala, Surat - 394 651, Gujarat
Source of Support: None, Conflict of Interest: None
The activity and gamma-absorbed dose rate due to the naturally occurring (226Ra, 232Th, and 40K) and anthropogenic (137Cs) radionuclides in the terrestrial environment were determined in soil samples collected around Mithivirdi Atomic Power Project Site, Bhavnagar District, Gujarat, by using gamma-ray spectrometry. The mean concentration levels measured in soil from the naturally occurring radioisotopes 226Ra, 232Th, and 40K are lower than the corresponding global average values reported worldwide. 137Cs activity in the soil sample is comparable with the preoperational baseline level activity of other nuclear power plant sites in India. The total outdoor effective dose rates due to soil ranged 16.7–79.5 μSv/y with the median value of 34.3 μSv/y. The absorbed dose rate due to cosmic components around Mithivirdi site was found to be in the range of 44.4–90.6 nGy/h.
Keywords: Cosmic, gamma dose rate, Mithivirdi, natural radioactivity
|How to cite this article:|
Patra AK, Jaison T J, Wagh S S, Jha M K, Saradhi I V, Kumar A V. Studies on natural and fallout radioactivity mapping of the proposed Mithivirdi Atomic Power Project Site in Bhavnagar District, Gujarat, India. Radiat Prot Environ 2021;44:12-8
|How to cite this URL:|
Patra AK, Jaison T J, Wagh S S, Jha M K, Saradhi I V, Kumar A V. Studies on natural and fallout radioactivity mapping of the proposed Mithivirdi Atomic Power Project Site in Bhavnagar District, Gujarat, India. Radiat Prot Environ [serial online] 2021 [cited 2022 Aug 13];44:12-8. Available from: https://www.rpe.org.in/text.asp?2021/44/1/12/317948
| Introduction|| |
Human beings are exposed to radiation arising from various sources including cosmic rays, naturally occurring radionuclides in water, air, soil, and plants, and artificial radioactivity from fallout of nuclear testing and medical applications. The gamma radiation from natural radionuclides and cosmic rays constitute the external exposure while those derived from inhalation and ingestion through food and drinking water constitute internal exposure to humans. It is estimated that 80% of dose contribution in the environment are derived from the natural radionuclides, while the remaining 20% are from cosmic ray and nuclear processes. The natural radioactivity in soil comes from 238U, 232Th, and from natural 40K. Some other terrestrial radionuclides, including those of the 235U series, 87Rb, 138La, 147Sm, and 176Lu, exist in nature, but at such low levels, their contributions to the dose in the humans are insignificant. Natural radioactivity is widely spread in the earth's environment and depends primarily on the geological and geographical conditions, and appears at different levels in the soils of each region in the world. The assessment of radiation dose from natural sources is important as natural radiation is the largest contributor to the external dose of the world population. Predominant parts of the natural radioactivity in soils derive from the members of the radioactive decay series of 238U and 232Th, along with 40K. Anthropogenic radionuclides present are widely distributed in the atmosphere primarily resulting from fallout from atmospheric nuclear weapon tests (e.g., 137Cs).
The primary objective of the present study is to determine the natural (226Ra, 232Th, and 40K) and anthropogenic (137Cs) radioactivity in soil samples collected around the proposed Mithivirdi Atomic Power Project (MAPP) site and its contribution to dose rate in the surrounding environment. In addition, the gamma radiation dose rate at 1 m above the ground in air, coming from cosmic radionuclides, was also investigated. This study was carried out as a part of preoperational environmental monitoring of proposed site.
| Materials and Methods|| |
The proposed MAPP site is located on latitude 21°28'8“ N and longitude 72°13'47” E in the western part of India, as shown in [Figure 1]. The site is about 13.6 m–21.2 m above sea level with the bay of Khambhat on the east. On the north side around 2 km from the site, Mithivirdi river meets the sea. The site is located at a distance of 40 km from district headquarter Bhavnagar city. The climate of the area is humid and hot. July to September/October is the monsoon season. The area around the location is used for agricultural purpose. The soil type is a mixture of sand, gravel, and clay as binder.
Geographical location and gamma radiation mapping
Latitude and longitude of different locations around MAPP site were measured by using Global Positioning System (12XL). Gamma radiation level was measured at each location by using gamma dose rate tracer.
Soil sample collection and estimation of radioactivity
A total of 30 soil samples were collected around Mithivirdi site, as shown in [Figure 1]. Soil samples were dried in an oven at 105°C for 24 h, and then crushed, ground to fine powder, and homogenized by passing through a 180-μm test sieve. About 300-g soil sample was sealed and stored in a precalibrated geometry of a 300-ml bottle for 1 month to allow the attainment of radioactive equilibrium with the decay chain. Natural radionuclides of relevance for this work are mainly gamma-ray-emitting radionuclide in the decay series of 232Th and 238U, and naturally occurring 40K. 137Cs and 40K are measured directly by characteristic gamma-rays of 662 keV and 1461 keV, respectively. The activity of 226Ra was determined by taking the weighted mean of their decay products: 214Bi (609 and 1120 keV) and 214Pb (352 keV). Similarly, the activity of 232Th was determined by taking the weighted mean of their decay products: 208Tl (583 and 2614 keV), 212Pb (238 keV), and 228Ac (911 keV). After attainment of secular equilibrium between 232Th and 226Ra with their daughter products, the samples were subjected to gamma-ray spectrometric analysis. The measurements were carried out by using gamma-ray spectrometer with a P-type coaxial high-purity germanium detector (Baltic Scientific make) of 100% relative efficiency and a resolution of 1.9 keV at 1332 keV gamma energy of 60Co. The system was calibrated for energy and efficiency using spiked soil sample and liquid standards containing 137Cs, 60Co, 133Ba, and 40K. The efficacy of the sample counting was verified by the analysis of certified reference material (International Atomic Energy Agency [IAEA]-375 soil and IAEA-444). The results agreed within ±5% of the certified values.
Calculation of gamma dose rate in outdoor air and effective dose rate
The total absorbed dose rate D (nGy/h) in air at 1 m above ground level due to the presence of natural radionuclides in the soil samples was estimated using the following formula:
D = 0.462 CRa + 0.604 CTh + 0.0417 CK + 0.030 CCs(1)
where CRa, CTh, CK, and CCs are the activity concentration of 226Ra, 232Th, 40K, and 137Cs (Bq/kg dry wt.), respectively.
In order to make a rough estimate for the annual effective dose outdoors, one has to take into account the conversion coefficient from absorbed dose in air to effective dose and the outdoor occupancy factor. In the UNSCEAR reports,, the committee used 0.7 Sv/Gy as the conversion coefficient from absorbed dose in air to effective dose received by adults, and 0.2 for the outdoor occupancy factor. Effective dose rate in outdoors (μSv/y) was calculated by the following formula:
Effective dose rate (μSv/y) = Dose rate (nGy/h)
× 24 h × 365d × 0.2 (occupancy factor) ×
0.7 Sv/Gy (conversion coefficient) × 10−3(2)
| Results and Discussions|| |
Gamma radiation mapping in and around Mithivirdi site
Gamma radiation levels are measured and the latitude and longitude of the locations are shown in [Table 1]. It is observed that the gamma radiation level was 0.022–0.21 μSv/h, with an average value of 0.093 μSv/h. The gamma radiation levels (μSv/h) around different nuclear power plant (NPP) sites in India are reported as 0.03–0.05 in Chutka, Mandla, Madhya Pradesh; 0.061–0.22 in Hisar, Fatehabad, Haryana; 0.035–0.12 in Kaiga, Karnataka; 0.02–0.20 in Jaitapur, Ratnagiri, Maharashtra; 0.05–0.08 in Kakrapar, Surat, Gujarat; 0.05–0.22 in Tarapur, Thane, Maharashtra; 0.16–0.20 in Narora, Uttar Pradesh; and 0.10–0.30 in Kudankulam, Tamil Nadu, respectively. The gamma radiation level of Mithivirdi site is comparable with other NPP sites in India.
|Table 1: Gamma dose rate level in and around Mithivirdi nuclear power plant site|
Click here to view
Distribution of natural and anthropogenic radioactivity in soil
The activity levels of 226Ra, 232Th, 40K, and 137Cs in soil samples collected from different locations are given in [Table 2]. The activity of 226Ra in the soil ranged 3.0–32.9 Bq/kg, 232Th ranged 10.0–72.5 Bq/kg, 40K ranged 25.6–331.3 Bq/kg, and 137Cs ranged 0.7–3.6 Bq/kg, respectively. Variation of 226Ra, 232Th, 40K, and 137Cs activity in soil samples is shown in [Figure 2]. It is observed that the mean concentration levels measured in Mithivirdi soil from naturally occurring radioisotopes such as 226Ra, 232Th, and 40K are lower than the corresponding global average values reported in [Table 3]. The 137Cs activity in Kakrapar Gujarat Site soil samples during the preoperational period (1992–1993) was observed to be in the range of 0.5–4.8 Bq/kg dry wt. The availability of this anthropogenic-produced radionuclide (137Cs) in the soil as a fallout radionuclide is mainly due to open atmospheric tests conducted by some countries prior to the ban of open atmospheric tests. Linear regression analysis was carried out for 226Ra versus 232Th and 40K versus 137Cs. A good correlation was observed between 226Ra versus 232Th with a correlation coefficient of 0.93 and no correlation was observed between 40K versus 137Cs shown in [Figure 3].
|Table 2: 226Ra, 232Th, 40K, and 137Cs activity levels (Bq/kg dry wt.) in soil samples collected in and around Mithivirdi nuclear power plant site|
Click here to view
|Table 3: Comparison of natural and anthropogenic radioactivity in soils of Mithivirdi site with different parts of the world|
Click here to view
|Figure 2: Variation of 226Ra, 232Th, 40K, and 137Cs activity in surface soil|
Click here to view
|Figure 3: Linear regression analysis of 226Ra versus 232Th and 40K versus 137Cs|
Click here to view
Measurement of absorbed dose rate and effective dose rate
The absorbed dose rate and effective dose rate in air outdoors were calculated from concentration of radionuclides of 238U series, 232Th series, 40K, and 137Cs using Equations 1 and 2 and are tabulated in [Table 2]. The absorbed dose rate in outdoor air was found to be in the range of 13.6–64.8 nGy/h with a median value of 28.0 nGy/h, which is below the corresponding world median value of 51 nGy/h and Indian value of 41.5 nGy/h. The total effective dose rate in air from soils ranged 16.7–79.5 μSv/y with the median value of 34.3 μSv/y. [Figure 4] illustrates the measured relative contributions to total effective dose in air due to 232Th, 226Ra, 40K, and 137Cs content in soil.
|Figure 4: Relative contributions to total effective dose in air outdoors due to 226Ra, 232Th, 40K, and 137Cs content in soil|
Click here to view
Tzortzis et al. reported the dose rate and effective dose rate in air outdoors at Cyprus as 0.1–50 nGy/h and 0.1–61.4 μSv/y. Ramli et al. reported the dose rate in air outdoors at Malaysian state of Johore as 9–1262 nGy/h. Mohanty et al., reported the dose rate and effective dose rate in air outdoors at eastern coast of Orissa as 650-3150 nGy.h-1 and 0.78-3.86 mSv.y-1, respectively. The reason is due to mainly monazite sands and to a lesser extent, zircons at eastern coast of Orissa. Singh et al. reported the dose rate in air outdoors at some areas of Punjab and Himachal Pradesh as 33–126 nGy/h. Malanca et al. reported the dose rate in air outdoors at Rio Grande do Norte (Brazil) as 15–179 nGy/h. Anagnostakis et al. reported the dose rate in air outdoors in Greece as 40 nGy/h.
The measurement of absorbed dose rate due to cosmic components is tabulated in [Table 4]. It is observed that the absorbed dose rate due to cosmic components around Mithivirdi site was found to be in the range of 44.4–90.6 nGy/h with an average of 62.5 ± 13.2 nGy/h which is comparable to the value of Japan (30.1–59.4), Indonesia (21.1–61.9), Taiwan (25.7–58.0), Iran (33.0–57.6), Sweden (32–50), and Italy (32–54), respectively.
| conclusions|| |
The activity concentrations of 226Ra, 232Th, 40K, and 137Cs in soil samples collected around Mithivirdi site were studied using gamma spectrometry. The outdoor absorbed dose rate in air was found to be in the range of 13.6–64.8 nGy/h with a median value of 28.0 nGy/h, which is below the corresponding world median value of 51 nGy/h and Indian value of 41.5 nGy/h. The estimated naturally occurring radioactivity in soil 226Ra, 232Th, and 40K is in the range commonly found elsewhere. The estimated total outdoor effective dose rates in air from soils ranged 16.7–79.5 μSv/y with the median value of 34.3 μSv/y. The absorbed dose rate due to cosmic components around Mithivirdi site was estimated to be in the range of 44.4–90.6 nGy/h.
The study indicates that the dose due to naturally occurring radionuclides around MAPP site is marginally less compared to global average value.
The authors would like to thank Site Director, Kakrapar Site; Station Director, KAPS-1&2 and ACE (E&US), ACE (Mithivirdi project) for their keen interest and encouragement. The assistance rendered by Smt. Padma Chaudhary, Shri M. K Chaudhary, Shri. J. J. Chaudhary, Late Shri. Mityabhai Chaudhary and all other ESL staff is thankfully acknowledged.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
International Atomic Energy Agency (IAEA), (1996). Radiation safety. Regulation for the safe transport of radioactive material. IAEA/PI/A47E, Vienna, IAEA Division of Public Information, p. 96-00725.
UNSCEAR. Sources and Effects of Ionizing Radiation. New York: United Nations Scientific Committee on the Effects of Atomic Radiation, United Nation; 2000.
UNSCEAR. Sources and Effects of Ionizing Radiation. New York: United Nations Scientific Committee on the Effects of Atomic Radiation, United Nation; 1993.
BARC. Preliminary Pre-Operational Environmental Survey Report of Chutka Atomic Power Project (CAPP 1&2), Mandla district, Madhya Pradesh; 2011.
BARC. Preliminary Pre-Operational Environmental Survey Report of Hisar Nuclear Power Plant Site in Fatehhabad district, Haryana; 2011.
BARC/1999/E/023, Report on the Pre-Operational Environmental Radiological and Micrometeorological Studies around Kaiga Atomic Power Project Site.
BARC/2007/I/003, Pre-Operational Environmental Surveillance Around Proposed Jaitapur Nuclear Power Plant Site in Ratnagiri District (Maharashtra), Bhabha Atomic Research Centre.
BARC/2002/I/002, Offsite Environmental and Micrometeorological Studies at Kakrapar Site (1993-1998).
BARC/HP/ESL-7, 1967-68, Pre-Operational Environmental Survey for Tarapur Atomic Power Project.
BARC/I-984/1989. Progress Report of Environmental Survey and Micrometeorology Laboratory, Narora for the Year; 1988.
BARC, 2004-2013. Pre-Operational Environmental Survey for Kudankulam NPP.
Patra AK, Jaison TJ, Baburajan A, Venkataraman S, Hegde AG. Assessment of radiological significance of naturally occurring radionuclides in soil and rock Matrices around Kakrapar environment. Radiat Prot Dosimetry 2008;131:487-94.
Wagh SS, Jaison TJ, Jain AK, Patra AK, Ravi PM, Hegde AG. Soil-to-plant Transfer Factor for 137Cs and 40K around KAPS site, Vizag, NUCAR, 2011, p. 3-4.
Patra AK, Sudhakar J, Ravi PM, James JP, Hegde AG, Joshi ML. Natural radioactivity distribution in geological matrices around Kaiga environment. J Radioanal Nucl Chem 2006;270:307-12.
Akhtar N, Tufail M, Ashraf M. Natural environmental radioactivity and estimation of radiation exposure from saline soils. Int J Enviorn Sci Technol 2004;1:279-85.
Yang YX, Wu XM, Jiang ZY, Wang WX, Lu JG, Lin J, et al
. Radioactivity concentrations in soils of the Xiazhuang Granite Area, China. Appl Radiat Isot 2005;63:255-9.
Lee SK, Wagiran H, Ramli AT, Apriantoro NH, Wood AK. Radiological monitoring: Terrestrial natural radionuclides in Kinta District, Perak, Malaysia. J Environ Radioact 2009;100:368-74.
Ademola AK, Bello AK, Adejumobi AC. Determination of natural radioactivity and hazard in soil samples in and around gold mining area in Itagunmodi, south-western, Nigeria. J Radiat Res Appl Sci 2014;7:249-55.
Abd El-Mageed AI, El-Kamel AH, Abbady A, Harb S, Youssef AM, Saleh II. Assessment of Natural and Anthropogenic Radioactivity Levels in Rocks and Soils in the Environs of Juban Town in Yemen, Tenth Radiation Physics & Protection Conference, 27-30 November 2010, Nasr City - Cairo, Egypt; 2010.
Selvasekarapandian S, Sivakumar R, Manikandan NM, Meen-akshisundaram V, Raghunath VM, Gajenndran V. Natural radionuclide distribution in soils of Gudalore, India, Appl Radiat Isot. 2000;52, p. 299-306.
Somashekarappa HM. Baseline Background Radiation Studies in the Environment of Kaiga, PhD Thesis, Mangalore University; 1993.
UNSCEAR. Sources and Effects of Ionisation Radiation. Vol. I. New York: UNSCEAR-2008 Report to the General Assembly with Scientific Annexes, United Nation; 2010. p. 329-31.
Tzortzis M, Tsertos H, Christofides S, Christodoulides G. Gamma-ray measurements of naturally occurring radioactive samples from Cyprus characteristic geological rocks. Radiat Meas 2003;37:221-9.
Ramli AT, Hussein AW, Lee MH. Geological influence on terrestrial gamma radiation dose rate in the Malaysian State of Johore. Appl Radiat Isot 2001;54:327-33.
Mohanty AK, Sengupta D, Das SK, Vijayan V, Saha SK. Natural radioactivity in the newly discovered high background radiation area on the eastern coast of Orissa, India. Radiat Meas 2004;38:153-65.
Singh S, Rani A, Mahajan RK. 226Ra, 232Th and 40K analysis in soil samples from some areas of Punjab and Himachal Pradesh, India using gamma ray spectrometry. Radiat Meas 2005;39:431-9.
Malanca A, Gaidolfi L, Pessina V, Dallara G. Distribution of 226Ra, 232Th, and 40K in Soils of Rio Grande do Norte (Brazil). J Environ Radioact 1996;30:55-67.
Anagnostakis MJ, Hinis EP, Simopoulos SE, Angelopoulos MG. Natural radioactivity mapping of Greek surface soil. Environ Int 1996;22 Suppl 1:S3-8.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]