[en] The field measurements of "3H in the form of HTO present in air moisture carried out around Madras Atomic Power Station were compared with predicted values using atmospheric dispersion modeling. Air "3H samples were collected from different sectors at the site boundary of the operating reactors for the period of 2 y and compared with Gaussian Plume model. The predictions were comparable with the measured value. The slight variation observed between the two methods is attributed to the uncertainty involved in the measurement of air "3H concentration and in the measurement of site-specific meteorological parameters. The radiation dose imparted to members of public due to the levels observed is well within station technical specification limit for "3H. (authors)

[en] Site-specific wet, dry deposition velocities and mass interception factors at Kaiga site, where three PHWR type power plants are operational, using ⁷Be as a tracer are presented. Mean wet and dry deposition velocities for Kaiga site were found to be 7.4x10^-2 m s^-1 and 3.0x10^-4 m s^-1, respectively. Mass interception factors for vegetation were found to be 0.7-5.6 m² kg^-1 dry weight with a mean of 2.4 m² kg^-1 dry weight. The site-specific data were used for the prediction of radionuclide distribution pattern in soil and vegetation in the case of a hypothetical air contamination. (authors)

[en] Tritium concentration in different parts of the rice plants, grown in villages around Tarapur Atomic Power Station, west coast of India, exposed to continuous atmospheric tritium in field condition were studied during two harvesting seasons of the years 2016 and 2017. The TFWT (HTO) and OBT concentrations in different parts of the rice plants were determined along with tritium in soil and air. The HTO to OBT concentration ratio in rice and hay was greater than unity in majority of the samples.

[en] Carbon content (%) measurement for determination of ¹⁴C specific activity (Bq kg⁻¹C) in environmental matrices based on thermal oxidation of the sample using pyrolyser is discussed. The carbon content in biota samples (N = 574) of the tropical region were in the range 30–45%, 28–47%, 31–46%, 32–45%, 43–49%, and 37–50% with corresponding mean values of 38 ± 3.1%, 38 ± 4.4%, 41 ± 3.1%, 41 ± 3.7%, 46 ± 1.5%, and 44 ± 5.1% respectively for wild plant leaves, vegetables, fruits, cereals, wood, and fish samples. The present study shows that carbon content within the species and category (fruit, leaves, vegetables, etc.) of the sample may differ up to ~ 20% points.

[en] In the transport model for the prediction of the concentration of ¹³⁷Cs in milk, the transfer coefficient from feed to milk, F_m, is an important parameter. Site-specific transfer coefficient from feed to cow's milk, for ¹³⁷Cs in the Kaiga environment, a nuclear power station site in India, determined over a period of 10 y is presented in this paper. The value is determined from ¹³⁷Cs concentration in milk and grass samples of the Kaiga region and the result ranged from 6.43 E-03 to 1.09 E-02 d l^-1 with a geometric mean value of 8.0 E-03 d l^-1. The result is compared with that for ⁴⁰K, determined concurrently at the same region and ranged from 3.06 E-03 to 3.48 E-03 d l^-1 with a geometric mean value of 3.26 E-03 d l^-1. This parameter is quite useful in decision-making for implementing countermeasures during a large area contamination with ¹³⁷Cs in tropical areas like Kaiga. (authors)

[en] Site-specific transfer coefficient from feed to cow's milk, for ¹³⁷Cs in the villages around Narora, a nuclear power station site in India, determined over a period of 17 y, is presented in this paper. In the transport model for the prediction of the concentration of ¹³⁷Cs in milk, the transfer coefficient from feed to milk, F_m, is an important parameter. The transfer coefficient value is determined from ¹³⁷Cs concentration in milk and grass samples of the Narora region, and the result ranged from 4.28E-03 to 3.30E-02 d l^-1 with a geometric mean value of 1.15E-03 d l^-1. The highest and the lowest values were only below one order of magnitude different from the mean, regardless of the type of diet, milk yield and age of the cow. The result is compared with that for ⁴⁰K, determined concurrently at the same region and ranged from 6.92E-03 to 8.01E-03 d l^-1 with a geometric mean value of 7.45E-03 d l^-1. This parameter is quite useful in decision-making for implementing countermeasures during a large-area contamination with ¹³⁷Cs in tropical areas like Narora. The ingestion dose from fallout ¹³⁷Cs through milk intake for adult and child is also estimated. (authors)

[en] Tritium content in air moisture, soil water, rain water and plant water samples collected around the Kaiga site (India) was estimated and the scavenging ratio, wet deposition velocity and ratio of specific activities of tritium between soil water and air moisture were calculated and the results are interpreted. Scavenging ratio was found to vary from 0.06 to 1.04 with a mean of 0.46. The wet deposition velocity of tritium observed in the present study was in the range of 3.3 E-03 to 1.1 E-02 m s.^-1 with a mean of 6.6 E-03 m s.^-1. The ratio of specific activity of tritium in soil moisture to that in air moisture ranged from 0.17 to 0.95 with a mean of 0.49. The specific activity of tritium in plant water in this study varied from 73 to 310 Bq l.^-1. The present study is very useful for understanding the process and modelling of transfer of tritium through air/soil/plant system at the Kaiga site. (authors)

[en] Optimization of a method, based on thermal oxidation using a tube furnace system (Pyrolyser), for the separation of organically bound tritium (OBT) from environmental matrices is discussed. Results show that a maximum of ~ 4 g of the vegetation sample, typical wild plant leaves of tropical regions, and ~ 8 g of sediment sample can be combusted efficiently in the pyrolyser system. The recovery of OBT from wheat sample was observed to be ~ 92% and that for sediment sample was ~ 88%. The minimum detectable activity (MDA) at 95% confidence level was 3.4 Bq kg⁻¹ for a sample weight = 4 g, counting time = 30,000 s, and detection efficiency = 23%.

[en] Tritium concentration was monitored in different water sources collected around Kaiga Nuclear Power plant, India. The concentration was in the ranges < 1.9–27.4 Bq L⁻¹ (GM = 4.0 Bq L⁻¹) for groundwater, < 1.9–42.1 Bq L⁻¹ (GM = 3.5 Bq L⁻¹) for surface water and in 12.4–42.0 Bq L⁻¹ (GM = 24.07 Bq L⁻¹) for reservoir water. The concentration values observed in this study are similar to those reported for other PHWR stations of the world. The radiation dose to the public due to ingestion of Tritium through groundwater was computed to be 0.08 μSvy⁻¹.

[en] Four 220 MWe pressurised heavy water reactors are under operation at Kaiga in the state of Karnataka in India. Environmental radiological survey of the surrounding areas of the Kaiga site is carried out by Bhabha Atomic Research Centre, Mumbai. The estimated dose to the members of the public due to ingestion of radioactive isotope of potassium, a natural radionuclide, in the surroundings of the Kaiga site is 136 μSv (13.6 mrem) per year. The value indicates that the dose to the public due to operation of the nuclear reactors in Kaiga is insignificant in comparison with the dose due to unavoidable natural radioactivity. (authors)