Negligible radiological impact of Indian nuclear power plants on the environment and the public: Findings from a 20-year study.

Nuclear power plants, recognized for their extended operational life, minimal greenhouse gas emissions, and high-power density, are deemed as reliable energy sources. Nonetheless, concerns persist regarding the radioactive discharges from these plants and their potential impact on health and the environment. To comprehend the radiological implications of such releases, this study presents, for the first time, an analysis of radiological data from 7 Indian nuclear power plants (NPPs), collected by Indian environmental survey laboratories (ESL) over the past two decades (2000-2020). This dataset encompasses radioactivity concentrations in the atmospheric, aquatic, and terrestrial environments within a 30 km radius of each NPP, as well as the annual cumulative external gamma doses recorded by environmental thermoluminescence dosimeters (TLDs). The analysis yielded several key findings: (i) Radioactivity concentrations around the NPPs were low and comparable to values measured at other nuclear power plant sites worldwide; (ii) Tritium concentrations in receiving water bodies were <1 % of the internationally recommended limit of 10,000 Bq/l; (iii) The estimated total radiation doses to the public were at most 10 % of the stipulated regulatory dose limit of 1000 µSv and consistently decreased over the study period and (iv) Variations in doses among the NPP sites were primarily attributed to legacy technology used in specific reactors. These results indicate efficient and secure reactor operations and the minimal contribution of Indian nuclear power plants to anthropogenic doses in the country. The findings hold potential significance for reinforcing India's commitment to advancing its nuclear power program.

Generation of map on natural environmental background absorbed dose rate in India.

A systematic mapping of natural absorbed dose rate was carried out to assess the existing exposure situation in India. The mammoth nationwide survey covered the entire terrestrial region of the country comprising of 45127 sampling grids (grid size 36 km2) with more than 100,000 data points. The data was processed using Geographic Information System. This study is based on established national and international approaches to provide linkage with conventional geochemical mapping of soil. Majority (93%) of the absorbed dose rate data was collected using handheld radiation survey meters and remaining were measured using environmental Thermo Luminescent Dosimeters. The mean absorbed dose rate of the entire country including several mineralized regions, was found to be 96 ± 21 nGy/h. The median, Geometric Mean and Geometric Standard Deviation values of absorbed dose rate were 94, 94 and 1.2 nGy/h, respectively. Among the High Background Radiation Areas of the country, absorbed dose rate varied from 700 to 9562 nGy/h in Karunagappally area of Kollam district, Kerala. The absorbed dose rate in the present nationwide study is comparable with the global database.

Studies on diurnal variation of atmospheric tritium concentration at a sampling location near to PHWR site in Semi-Arid Zone, India.

Tritium (3H) is one of the important long-lived radioisotopes in the gaseous effluent released from Pressurised Heavy Water Reactors (PHWR). For the first time, the studies on diurnal variation of atmospheric tritium concentration was carried out using an in-house developed automatic air moisture collection sampler at Kakrapar Gujarat site, India, where PHWRs are operational. Correlation of diurnal variation of atmospheric tritium concentration with meteorological parameters such as absolute humidity, ambient temperature and wind speed is studied and presented in this paper. Positive and significant correlation of atmospheric 3H concentration was observed with respect to the absolute humidity. Negative correlation was observed in ambient temperature and wind speed. The diurnal maximum and minimum of 3H concentration was found during 21.00-23.00 h (night) and 13.00-16.00 h (day), respectively.

SITE-SPECIFIC DRY AND WET DEPOSITION VELOCITIES USING 7BE AND MASS INTERCEPTION FACTOR FOR VARIOUS TYPES OF PLANT LEAVES AT NARORA SITE, INDIA.

Comprehensive studies were carried out during the period 2016-19 on the estimation of site-specific wet and dry deposition velocities and the mass interception factor for Narora site based on the concentrations of 7Be in air, air deposits, rain water and vegetation samples. Mean wet and dry deposition velocities for Narora site were found to be 1.64E-2 and 1.58E-3 m s-1, respectively. Mass interception factors for vegetation found to be 0.34-2.51 m2 kg-1 dry weight with a mean of 0.97 m2 kg-1 dry weight. The obtained parameters shall be used for estimation of impact due to radionuclide related to Narora Atomic Power station.

NATURALLY OCCURRING RADIONUCLIDE 40K BODY CONTENT OF KAKRAPAR GUJARAT SITE POPULATION.

An attempt was made to investigate the naturally occurring radionuclide 40K body content of the Kakrapar Gujarat Site (India) population by using whole-body counting method. The population comprises occupational workers (regular and contract personnel working at Kakrapar Atomic Power station) and students from various educational institutions. A total of 1056 subjects of different age groups and gender were monitored for 40K body content by using a Standfast-II Whole Body Counting System. The reactor released radionuclides such as 137Cs, 60Co and 131I are not detected in occupational workers of Kakrapar Atomic Power station which indicates that occupational workers are free from radioactive contamination. Based on the activity measurement, an effective dose due to 40K was estimated for different groups of the site population based on the dietary habits, sex and age. Statistical significant correlation was not observed in any of the groups. The annual effective dose due to 40K was found to be in the range of 52-243 µSv y-1 with an average of 133 ± 35 µSv y-1 for the vegetarian group (588 subjects), 60-223 µSv y-1 with an average of 136 ± 35 µSv y-1 for the non-vegetarian group (468 subjects), 52-243 µSv y-1 with an average of 134 ± 35 µSv y-1 for the male group (1007 subjects) and 67-203 µSv y-1 with an average of 128 ± 35 µSv y-1 for the female group (49 subjects), respectively. Among the four age groups of the population studied, an effective dose due to 40K is slightly higher in the age group of 20-29 (161 subjects). The annual effective dose due to 40K reported by UNSCEAR, 1982(3) is 180 µSv y-1.

Seasonal variation of black carbon in fine particulate matter (PM2.5) at the tropical coastal city of Mumbai, India.

Black Carbon (BC) is a pollutant species primarily emitted from the combustion of fossil fuels. BC levels, associated with fine particulate matter (PM2.5), were monitored from January 2009 to December 2010 at an urban industrial area in Mumbai to study the seasonal and temporal variations and its contribution to fine particulate matter. Air particulate samples were collected in two size fractions, fine particulate matter (PM2.5) and coarse particulate matter (PM2.5-10), using a Gent air sampler. During the study period, arithmetic means of PM2.5 and PM2.5-10 were found to be 30.4 and 68.2 µg/m(3), respectively. The average value of BC in fine particulate matter was 4.0 µg/m(3), with a range of 1.0-9.4 µg/m(3). Studies carried out using Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated the contribution of BC from the northern and central part of India during days of high BC levels.

Chemical characterization of precipitation at a coastal site in Trombay, Mumbai, India.

Precipitation is the best scavenger for the particulates and dissolved gaseous pollutants present in the atmosphere. The chemical composition of precipitation is dominated by a number of in-cloud and below-cloud scavenging processes. The present study is aimed at analyzing the chemical composition of rainwater in the relatively less industrialized part of Mumbai. The pH of rainwater in this region ranges from 4.8 to 6.4. The percentage contributions of ions were calculated and the major contributing ions were calcium (28%), chloride (23%), sodium (18%), sulfate (14%), magnesium (11%), ammonium (4%), potassium (1%), and nitrate (1%). The correlation coefficient is highest for Na and Cl (r(2) = 0.99), giving a clear indication of contribution from sea salt. Sulfate and nitrate ions also show a very good correlation (r(2) = 0.90), which may be due to their coemission from fossil fuel combustion. Acidification caused by these ions is neutralized by Ca, Mg, and NH(4) ions. The neutralization effect due to these ions is validated by calculating the neutralization factor (NF). The NF values are in the order Ca > Mg > NH(4). The major source contributors for the ions in precipitation are sea salt (Na, Cl, and K) and fossil fuel combustion (SO(4) and NO(3)). These assumptions are supported by the values of wet-only ratio, enrichment factor, and percent sea salt fraction.

Trace metals and organometals in selected marine species and preliminary risk assessment to human beings in Thane Creek area, Mumbai.

Trace metals and organometals were estimated in different types of marine organisms (fish, bivalve, crab and prawn) collected from the Trans-Thane Creek area, Mumbai. Thane Creek area is considered as most polluted area due to industrial discharges. Potential risks associated with consumption of marine organisms collected from this particular area to human beings were assessed. Concentrations of ten trace elements (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn) in the edible part of marine organisms were analysed by atomic absorption spectrometer and differential pulse anodic stripping voltametric technique. Methyl mercury and tributyl tin were estimated using gas chromatograph-mass spectrometer in combination with solid phase micro extraction (SPME). An assessment of the risk on human beings due to consumption of marine organism was undertaken using toxic reference benchmark, namely the reference dose (RfD). The hazard index (HI), sum of hazard quotients calculated for all the pollutant showed that the risks from consumption of fish and marine organisms as a whole were generally low and are within safe limits.