|Year : 2018 | Volume
| Issue : 1 | Page : 16-19
Tritium concentration in ambient air around Kaiga Nuclear Power Plant
Srinivas S Kamath1, B Narayana1, Renita Shiny D'Souza2, Rashmi Nayak2, MP Mohan2, BN Dileep3, A Baburajan4, PM Ravi5, N Karunakara2
1 Centre for Advanced Research in Environmental Radioactivity; Department of Studies in Chemistry, Mangalore University, Mangalagangothri, Karnataka, India
2 Centre for Advanced Research in Environmental Radioactivity, Mangalore University, Mangalagangothri, Karnataka, India
3 Environmental Survey Laboratory, Kaiga Generating Station, Kaiga, Karnataka, India
4 Environmental Survey Laboratory, Tarapur Atomic Power Station, Tarapur, Maharashtra, India
5 Health Physics Division, Bhabha Atomic Research Centre, Trombay; Homi Bhabha National Institute, Mumbai, Maharashtra, India
|Date of Submission||31-Jan-2018|
|Date of Decision||12-Feb-2018|
|Date of Acceptance||04-Mar-2018|
|Date of Web Publication||31-May-2018|
Dr. N Karunakara
Centre for Advanced Research in Environmental Radioactivity, Mangalore University, Mangalagangothri, Mangalore - 574 199, Karnataka
Source of Support: None, Conflict of Interest: None
Tritium (3H) is one of the important long-lived radioisotopes in the gaseous effluent from nuclear power plants. In this article, we present the results of 3H monitoring in ambient air samples around the Kaiga Nuclear Power Plant, on the West Coast of India. Air samples were collected by moisture condensation method and the 3H concentration was determined by liquid scintillation spectrometry. The 3H concentration in the 2.3–15 km zone of the power plant varied in the range of <0.04–6.64 Bq m−3 with a median of 0.67 Bq m−3. The samples collected from the 2.3–5 km zone of the power plant exhibit marginally higher concentration when compared to the 5–10 km and 10–15 km zones, which is as expected. The values observed in the present study for Kaiga region are similar to those reported from other nuclear power plants, both within India and other parts of the world.
Keywords: Ambient air, Kaiga, nuclear power plant, tritium
|How to cite this article:|
Kamath SS, Narayana B, D'Souza RS, Nayak R, Mohan M P, Dileep B N, Baburajan A, Ravi P M, Karunakara N. Tritium concentration in ambient air around Kaiga Nuclear Power Plant. Radiat Prot Environ 2018;41:16-9
|How to cite this URL:|
Kamath SS, Narayana B, D'Souza RS, Nayak R, Mohan M P, Dileep B N, Baburajan A, Ravi P M, Karunakara N. Tritium concentration in ambient air around Kaiga Nuclear Power Plant. Radiat Prot Environ [serial online] 2018 [cited 2020 Jan 18];41:16-9. Available from: http://www.rpe.org.in/text.asp?2018/41/1/16/233651
| Introduction|| |
Tritium (3 H) is a radioactive isotope of hydrogen (T1/2= 12.3 years); it decays to 3 He by emitting low-energy beta radiation with an average energy of 5.7 keV and a maximum energy of 18.6 keV. The 3 H is produced naturally in the environment by the interaction of high-energy cosmic rays with oxygen and nitrogen atoms in the upper atmosphere. Human activities also contribute to tritium levels in the environment; a significant amount of 3 H was released into the atmosphere as a result of thermonuclear bomb testing conducted primarily between 1954 and 1963. Tritium is also produced as a by-product of the operation of nuclear reactors during the fission of heavy nuclei and by neutron interaction with coolants, moderators, and some light elements, such as lithium, beryllium, and boron. While a major component of the product is contained or recovered, a very small component may be released into the atmosphere in the form of tritiated water vapor (HTO) and as tritium gas (HT) from tritium removal facilities and as both HTO and HT by tritium processing facilities. However, such releases are strictly monitored and are kept well within the permissible limits set by the regulatory authority.
Once released into the atmosphere, HTO can be incorporated into plants through photosynthesis or deposited to soil and incorporated into soil moisture. During metabolic activities, a portion of the HTO will become incorporated into organic molecules, including plant structural material or soil organic matter. Hence, monitoring of the environment around the nuclear power plant is important to ensure that the 3 H levels are well within the permissible limits. In this article, we report the 3 H activity in air samples collected at different locations around Kaiga Nuclear Power Plant, India, where four pressurized heavy water reactors of 220 MWe each are in operation.
| Materials and Methods|| |
Kaiga Nuclear Power Plant (Latitude: 14° 52' 18.5'' N, Longitude: 74° 24' 15.8'' E) is situated on the banks of the river Kali which emerges from deep gorges carved out of the steep west bank of the world famous Western Ghats in the state of Karnataka, Peninsular India. It is about 30 km aerial distance from the west coastal town of Karwar [Figure 1]a. Kaiga region is surrounded by hills with tropical forests and altitude ranges from 40 to 600 m from the mean sea level. The topography of Kaiga is like a bowl structure as it is surrounded by hills in all the sides. The annual rainfall in the area varies from 3500 mm to 4500 mm. The wind rose diagram for Kaiga is shown in [Figure 1]c.
|Figure 1: Map showing (a) location of Kaiga in the west coast of India, (b) sampling locations in Kaiga, and (c) wind rose diagram for Kaiga region|
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The locations identified for air sampling are shown in [Figure 1]b, and they are distributed in the 2.3–5 km, 5–10 km, and 10–15 km radius zones of Kaiga region, with Kaiga nuclear power station as the center of each zone. Air sampling was carried out by moisture condensation method, in which the moisture content present in ambient air is condensed using ice cubes and collected in a suitable collector. The experimental arrangement for collection of the sample is shown in [Figure 2]. Ice cubes were filled in a beaker and placed in a Petri dish plate. The moisture present in the air gets condensed into water when it comes into contact with the cool surface of the glass beaker and gets collected in the Petri dish. After sampling, 10 ml of condensed water was transferred to a liquid scintillation counting vial (Perkin Elmer, USA) and 10 ml of Ultima Gold ™ uLLT scintillator (Perkin Elmer, USA) was added, mixed thoroughly, and kept overnight for the decay of chemiluminescence. The sample was then analyzed in a ultra-low background liquid scintillation spectrophotometer (Quantulus 1220, Perkin Elmer, USA). The optimization of the liquid scintillation technique, such as evaluation of the figure of merit (FoM), sample-to-scintillator ratio, and quench correction, was published elsewhere. The minimum detectable activity (MDA) at 3σ confidence level for this counting system for a counting time of 100 min and for a sample (water) to scintillator combination of 10 mL + 10 mL was found to be 0.04 Bq m −3. The MDA value achieved at the Centre for Advanced Research in Environmental Radioactivity is similar to those reported for other leading laboratories of the world.
| Results and Discussion|| |
A total of 34 air samples were collected and analyzed for 3 H concentration during different seasons of the years 2016–2017. The results of these measurements are presented in [Table 1]. The activity concentrations are reported in units of Bq m −3 of air and it varied in the range of <0.04–6.64 Bq m −3 with a median value of 0.67 Bq m −3, considering all sampling stations in 2.3–15 km zone. The median values for the three sampling zones, namely, 2.3–5 km, 5–10 km, and 10–15 km were 1.32 Bq m −3, 0.45 Bq m −3, and 0.67 Bq m −3, respectively. This suggests that the samples collected from 2.3-5 km zone of the power plant exhibit marginally higher concentration when compared to the other two zones, which is as expected. While all the samples collected from 2.3 to 5 km zone exhibited measurable concentration of 3 H, some of the samples from 5 to 10 km and 10 to 15 km zone exhibited concentration below the detection level. The frequency distribution of the observed activity concentration is presented in [Figure 3], from which it is clear that majority of the samples exhibited activity <1.0 Bq m −3.
[Table 2] presents a comparison of the 3 H concentration observed in the present study with those reported for other nuclear power plants, both within India and other parts of the world. The details of different power plants, for which the reported values of 3 H are available, and the area covered under the studies are also presented in the same table. The values observed in the present study for Kaiga region are similar to those reported for other power plants, both from India and other parts of the world. The values reported for Kakrapar Atomic Power Station vary from <0.5 to 15.7 Bq m -3 and <0.2 to 19.9 Bq m -3 for 0–5 km and 0–30 km zones, respectively, and these are similar to the values observed in the present study. Furthermore, the values observed in the present study are similar to those reported for Wolsong and Vinca Nuclear Power Plants.
|Table 2: Comparison of Tritium activity in air samples of different nuclear power stations|
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| Conclusions|| |
The present study has established a reliable database on 3 H concentration in air around the Kaiga Nuclear Power Plant. The 3 H concentration varied in the range of <0.04–6.64 Bq m −3 with a median value of 0.67 Bq m −3. The samples collected from 2.3-5 km zone of the power plant exhibit marginally higher concentration when compared to the other two zones. The values observed in the present study for Kaiga region are similar to those reported for other power plants, both in India and other parts of the world.
The authors would like to thank the Board of Research in Nuclear Science, Department of Atomic Energy, Government of India, for funding the research program. Authors would also like to thank the Site Director and other officials of Kaiga Generating Station, Nuclear Power Corporation of India for supporting this research programme. The help received from Mr. S S Managhanvi and his colleagues, Health Physics Unit, Kaiga Generating Station, Kaiga during sample collection is thankfully acknowledged. 
Financial support and sponsorship
Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy, Govt. of India.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]