Uptake of 210Po by aquatic plants of a fresh water ecosystem around the uranium mill tailings management facility of Jaduguda, India.

PURPOSE: The present study was designed to investigate the uptake of Polonium-210 ((210)Po) by aquatic plants growing in a fresh water ecosystem around the tailings management facility of the uranium industry of Jaduguda, India. Evaluation of the activity concentration of (210)Po in aquatic plants, the concentration ratio of (210)Po from substrate to plants and the relationship of (210)Po with other stable elements were major objectives of the investigation. MATERIALS AND METHODS: Based on the habitat, three types of plant were collected and analyzed for (210)Po activity estimation. Along with aquatic plants, effluent, surface water and bottom sediment were also collected and analyzed for (210)Po activity content. From the acid solution (210)Po was electrodeposited on brightly polished silver discs and counted for alpha activity in an alpha counter. RESULTS: The highest (210)Po activity concentration (4884 Bq kg(-1) fresh weight) was found in filamentous algae from residual water of the tailings pond. For sediment-rooted plants, a significant positive correlation (r = 0.91, p < 0.0001) was observed between plant and sediment activity concentration of (210)Po. CONCLUSIONS: For all of the three different groups of plants studied, highly significant correlations were observed between activity concentration of (210)Po and Cu with the significance level variation between 0.00-0.05 (both for linear and log transformed data).

Distribution of norm and 137Cs in soils of the Visakhapatnam region, Eastern India, and associated radiation dose.

The specific activity of naturally occurring radioactive materials and (137)Cs in surface soils around the new Bhabha Atomic Research Centre site at Visakhapatnam region, Eastern India, has been determined using high-resolution gamma-ray spectrometry as part of a baseline radiological survey. Radiation hazard for the samples was assessed by radium equivalent activity (Raeq) and absorbed gamma dose rate (D). The mean absorbed gamma dose rate was found to be 104.9 nGy h(-1). The average annual effective dose equivalent was found to be 0.13 mSv y(-1).

Age-dependent dose and health risk due to intake of uranium in drinking water from Jaduguda, India.

Uranium is a heavy metal that is not only radiologically harmful but also a well-known nephrotoxic element. In this study, occurrence of uranium in drinking water samples from locations near the uranium mining site at Jaduguda, India, was studied by Laser-induced fluorimetry. Uranium concentrations range from 0.03 ± 0.01 to 11.6 ± 1.3 µg l(-l), being well within the US Environmental Protection Agency drinking water limit of 30 µg l(-1). The ingestion dose due to the presence of uranium in drinking water for various age groups varies from 0.03 to 28.3 µSv y(-1). The excess lifetime cancer risk varies from 4.3×10(-8) to 1.7×10(-5) with an average value of 4.8×10(-6), much less than the acceptable excess lifetime cancer risk of 10(-3) for radiological risk. The chemical risk (hazard quotient) has an average value of 0.15 indicating that the water is safe for drinking.

Distribution of radionuclides in surface soils, Singhbhum Shear Zone, India and associated dose.

Gamma emitters were estimated in surface soils from a mineralized zone in Eastern India using high purity Germanium detector-based high resolution gamma spectrometry system. Activities of (238)U, (226)Ra, (232)Th, (235)U, (227)Th, (234 m)Pa, (210)Pb, (40)K, and (137)Cs were 79 ± 50, 81 ± 53, 65 ± 23, 4 ± 2, 5 ± 4, 92 ± 50, 97 ± 45, 517 ± 201, and 4 ± 2 Bq/kg, respectively. Most radionuclides were observed to follow log-normal distribution. The correlation between physicochemical properties of the samples, like pH, organic matter content, particle size, and moisture content were also studied. Activity ratios of (226)Ra/(238)U, (210)Pb/(226)Ra, and (227)Th/(235)U indicated deviation from secular equilibrium in some samples. The associated annual effective dose ranged from 0.07 to 0.24 mSv and the mean was calculated to be 0.12 ± 0.04 mSv for this region, indicating it to be one of normal natural background radiation.

Comparison study and thoron interference test of different radon monitors.

A comparison study and thoron interference test for different continuous radon monitors were carried out. The comparison study includes three passive diffusion monitors [one pulse ionisation chamber based-Alpha Guard and two silicon semi-conductor based-Radon Scout Plus (RSP)] and one silicon semi-conductor-based active radon thoron discriminating monitor--RAD 7. Radon emanation standard, supplied by National Institute of Science and Technology, has been utilised for the comparison study to qualify the calibration of the continuous radon monitors. All the instruments showed good agreement with the estimated radon concentration using (226)Ra/(222)Rn emanation standard. It was found that the active radon monitoring system is having a higher initial response towards the transient radon concentration than the passive radon monitors studied. The instruments measuring radon concentration without energy discrimination are likely to have some sensitivity towards the thoron concentration. Thus, thoron interference study was carried out in the above monitors. Nine percent interference in measured radon concentration in the Alpha Guard monitor and 4 % interference in the semi-conductor-based RSP monitors was observed. Study indicates that the interference of thoron in radon monitors depends on the area of diffusion of gas, volume of detection and sensitivity factor.

Application of thoron interference as a tool for simultaneous measurement of radon and thoron with a pulse ionisation chamber.

Pulse ionisation chamber (PIC)-based monitors measuring radioactive gas radon ((222)Rn) without energy discrimination will have interference due to thoron ((220)Rn) present in the atmosphere. A technique has been developed to use this property of interference for simultaneous measurement of radon and thoron gas. These monitors work on the principle of counting of gross alphas emitted from radon and its progeny. A theoretical model has been developed for the variation of thoron sensitivity with respect to the flow rate of gas through the monitor. The thoron sensitivity of the monitor is found to vary with the flow rate of gas through the monitor. Using this sensitivity, the sampling procedure has been developed and verified for simultaneous measurement of radon and thoron. The PIC-measured radon and thoron concentration using this procedure agrees well with those measured by using standard radon and thoron discriminating monitor.

Ingestion dose from 238U, 232Th, 226Ra, 40K and 137Cs in cereals, pulses and drinking water to adult population in a high background radiation area, Odisha, India.

A natural high background radiation area is located in Chhatrapur, Odisha in the eastern part of India. The inhabitants of this area are exposed to external radiation levels higher than the global average background values, due to the presence of uranium, thorium and its decay products in the monazite sands bearing placer deposits in its beaches. The concentrations of (232)Th, (238)U, (226)Ra, (40)K and (137)Cs were determined in cereals (rice and wheat), pulses and drinking water consumed by the population residing around this region and the corresponding annual ingestion dose was calculated. The annual ingestion doses from cereals, pulses and drinking water varied in the range of 109.4-936.8, 10.2-307.5 and 0.5-2.8 µSv y(-1), respectively. The estimated total annual average effective dose due to the ingestion of these radionuclides in cereals, pulses and drinking water was 530 µSv y(-1). The ingestion dose from cereals was the highest mainly due to a high consumption rate. The highest contribution of dose was found to be from (226)Ra for cereals and drinking water and (40)K was the major dose contributor from the intake of pulses. The contribution of man-made radionuclide (137)Cs to the total dose was found to be minimum. (226)Ra was found to be the largest contributor to ingestion dose from all sources.

Spatial distribution of fallout 137Cs in the coastal marine environment of India.

The data on the fallout (137)Cs in the coastal marine environment assume significance in view of massive expansion of nuclear power plants in the Asia-Pacific region and to fulfill the benchmark study required to evaluate the possible impact of the Fukushima radioactive releases in the Asia-Pacific region. Measurements of (137)Cs in sea water, along with salinity and temperature, were carried out at 30 locations covering the coastal area of the Arabian Sea and the Bay of Bengal. For the present study the Indian coastal area is divided in three different regions. The (137)Cs concentration in sea water of the entire Indian coastal region varies from 0.30 to 1.25 Bq m(-3). The data obtained in the present study was compared with the North Indian Ocean data and it was observed that there is a 33% decrease in the Arabian Sea (region I), 50% in the high rainfall coastal area (region II) and 24% in the Bay of Bengal (region III).

Estimation of thoron concentration using scintillation cell.

Two counting techniques are proposed in this paper to estimate thoron ((220)Rn) concentration using a Lucas scintillation cell. The alpha activity build-up inside the cell is calculated theoretically by using Bateman equations. The first method is having a minimum detection limit of 325 Bq m(-3) and can be used for thoron measurement in thorium-processing plants. In the second method, thoron concentration is calculated using the alpha counts from thoron progenies and is a reference to the first method. The results obtained by these techniques compare well with the double filter method.

Assessment of age-dependent uranium intake due to drinking water in Hyderabad, India.

A study has been done to assess the uranium intake through drinking water. The area of study is twin cities of Hyderabad and Secunderabad, India. Uranium concentration in water samples was analysed by laser-induced fluorimetry. The associated age-dependent uranium intake was estimated by taking the prescribed water intake values. The concentration of uranium varies from below detectable level (minimum detectable level = 0.20 ± 0.02 µg l(-1)) to 2.50 ± 0.18 µg l(-1), with the geometric mean (GM) of 0.67 µg l(-1) in tap water, whereas in ground water, the range is 0.60 ± 0.05 to 82 ± 7.1 µg l(-1) with GM of 10.07 µg l(-1). The daily intake of uranium by drinking water pathway through tap water for various age groups is found to vary from 0.14 to 9.50 µg d(-1) with mean of 1.55 µg d(-1).

Study of the distribution of ²²6Ra in ground water near the uranium industry of Jharkhand, India.

Ground water is the principal source of drinking water in the rural areas of India. With the aim of determining, the contribution of (226)Ra to natural background radiation through drinking water exposure pathway near an operating uranium mining industry at Jaduguda, Jharkhand state of eastern India, the (226)Ra activity concentrations were measured in potable ground water. The water analysed, both tube well and well water, was collected in areas near the uranium industry and away. The (226)Ra concentration was measured by emanometric technique. The (226)Ra level in ground water was ranging between minimum detection limit of 3.5 mBq l(-1) and a maximum of 208 mBq l(-1). The analysis of variance reveals that there is insignificant statistical variation in the median (226)Ra concentration up to a distance of >10 km from the mining complex. Variation in concentration of (226)Ra in sources is attributed to the local geochemistry and environmental factors. The (226)Ra concentration was significantly elevated in natural artesian wells in the vicinity of uranium mineralised hill and it varies from 53.4 to 754 mBq l(-1). The WHO [Guidelines for Drinking Water Quality. Third Edition, Vol. 1, Recommendation (2004)] guideline value of 1000 mBq l(-1) has not been exceeded in any of the sources investigated.

Intake of ²³8U and ²³²Th through the consumption of foodstuffs by tribal populations practicing slash and burn agriculture in an extremely high rainfall area.

The concentration of naturally occurring radionuclides ²³²Th, ²³8U was determined using Instrumental Neutron Activation Analysis (INAA) in different food groups namely cereals, vegetables, leafy vegetables, roots and tubers cultivated and consumed by tribal population residing around the proposed uranium mine. The study area is a part of rural area K. P. Mawthabah (Domiasiat) in the west Khasi Hills District of Meghalaya, India located in the tropical region of high rainfall that remains steeped in tribal tradition without much outside influence. Agriculture by Jhum (slash and burn) cultivation and animal husbandry are the main occupation of the tribal populations. A total of 89 samples from locally grown food products were analyzed. The concentration of ²³8U and ²³²Th in the soil of the study area was found to vary 1.6-15.5 and 2.0-5.0 times respectively to the average mean value observed in India. The estimated daily dietary intake of ²³8U and ²³²Th were 2.0 µg d⁻¹ (25 mBq d⁻¹) and 3.4 µg d⁻¹ (14 mBq d⁻¹) is comparable with reported range 0.5-5.0 µg d⁻¹ and 0.15-3.5 µg d⁻¹ respectively for the Asian population.

An assessment of the radiological scenario around uranium mines in Singhbhum East district, Jharkhand, India.

The present work deals with the prevalent radiological scenario around uranium-mining sites in the Singhbhum East district of Jharkhand state, India. The concentration of naturally occurring radioactive materials (NORMs) was estimated from 27 soil samples collected around three regions in the study area, namely Bagjata, Turamdih and Jaduguda. The mean activity concentrations of (238)U in Bagjata, Turamdih and Jaduguda regions were found to be 128.6, 95.7 and 49.2 Bq kg(-1), respectively. Similarly for (232)Th and (40)K the activity concentrations were found to be 57.3, 78.4, 68.9 and 530, 425 and 615 Bq kg(-1) in the Bagjata, Turamdih and Jaduguda regions, respectively, which are comparable with other reported values worldwide, except for some high values. The calculated gamma dose rate, obtained from the concentrations of (238)U, (232)Th and (40)K in the samples, was compared with the observed dose rate in air. A good correlation (0.96) was observed between the calculated and the observed gamma dose rate. The annual outdoor effective dose rate was estimated and the values falls between 0.04-0.3, 0.07-0.3 and 0.07-.14 mSv y(-1) with mean values of 0.14, 0.12 and 0.11 mSv y(-1) for the Bagjata, Turamdih and Jaduguda regions, respectively. The terrestrial dose rates in all the three regions are comparable with other reported values worldwide, except for a few high values in Greece, Rio Grande Do Norte (Brazil) and Kalpakkam (India).

Radon in the environment and in dwellings in a uranium mining area in eastern India: an overview.

Radon has been extensively studied in the Singhbhum Thrust Belt (STB) of eastern India where mining and processing of uranium ore has been in progress for over four decades. Emanation from the soil is the main natural source of environmental radon. Releases from mine and emanations from waste rocks and tailings are the technological sources. Rn studies in the environment, dwellings and ground waters in STB are reviewed in this paper.

Long-term leaching of uranium from different waste matrices.

A semi-dynamic leaching test was carried out for metallurgical wastes and ore samples from the uranium and copper mining industry over a 142 day period using distilled water and 0.1N NaNO(3) as solvents. Laser fluorimetry was used as the analytical technique to determine the total uranium content in the leachates. The cumulative leach fraction (CLF) of uranium release from the samples was calculated to be 0.22, 0.22, 0.07 and 0.39% for rock, uranium tailings, copper kinker ash samples and copper tailings respectively using distilled water as solvent and 0.31, 0.27, 0.05 and 0.59% for the same matrices using 0.1N NaNO(3). The release of mobile uranium fraction was very slow, being faster in the initial stage and then attained a near steady state condition. The diffusion coefficient and bulk release of uranium from the samples have been calculated. The processes governing the release of uranium from these matrices have been identified to be surface wash-off and diffusion. Hence the use of weak solvents (leach out the mobile/exchangeable fraction of uranium) under semi-dynamic conditions aids the determination of leaching parameters and identification of the leaching mechanism for mobile uranium fraction from different matrices by slow leaching processes.

Radiation dose to members of public residing around uranium mining complex, Jaduguda, Jharkhand, India.

Uranium mining activities in the Jaduguda region of Jharkhand state, India have been carried out for the last five decades. Radioactive releases from mines, ore processing facility and tailings pond may increase the natural radiation dose to members of the public residing around the complex. It is, therefore, imperative to investigate the radiological condition around the uranium mining complex and assess the dose received by them. In the present study, it was estimated that the average radiation dose from all exposure pathways to the public living in villages around the mining complex is 2.5 mSv y(-1) and around 50 % contributed due to inhalation of radon and its progeny. The external radiation dose due to terrestrial and cosmic activity is estimated to be 1.1 mSv y(-1), which is 40 % of the total dose and ingestion dose contributes only 3% to the total dose.

Bioaccumulation of 226Ra by plants growing in fresh water ecosystem around the uranium industry at Jaduguda, India.

A field study has been conducted to evaluate the (226)Ra bioaccumulation among aquatic plants growing in the stream/river adjoining the uranium mining and ore-processing complex at Jaduguda, India. Two types of plant group have been investigated namely free floating algal species submerged into water and plants rooted in stream & riverbed. The highest (226)Ra activity concentration (9850 Bq kg(-1)) was found in filamentous algae growing in the residual water of tailings pond. The concentration ratios of (226)Ra in filamentous algae (activity concentration of (226)Ra in plant Bq kg(-1) fresh weight/activity concentration of (226)Ra in water Bq l(-1)) widely varied i.e. from 1.1 x 10(3) to 8.6 x 10(4). Other aquatic plants were also showing wide variability in the (226)Ra activity concentration. The ln-transformed filamentous algae (226)Ra activity concentration was significantly correlated with that of ln-transformed water concentration (r = 0.89, p < 0.001). There was no correlation between the activity concentrations of (226)Ra in stream/riverbed rooted plants and the substrate. For this group, correlation between (226)Ra activity concentration and Mn, Fe, Cu concentration in plants were statistically significant.

Aerosol size distribution in a uranium processing and fuel fabrication facility.

In the nuclear fuel complex, magnesium diuranate is processed to produce UO(2) through different chemical and metallurgical processes. UO(2) powder is compacted to produce uranium pallets as fuel. International Commission on Radiological Protection has considered default particle size of 5-mum activity median aerodynamic diameter (AMAD) and 2.5 of geometric standard deviation (GSD) for working out dose coefficients. There is a likelihood of variation in the particle size during each stage of operation. The present study is undertaken to determine the prevailing uranium aerosol size distribution at every stage of operation using Anderson impactor with glass fibre filter paper as collection substrate. AMAD and respective GSD were determined. Aerosol size distribution was studied. Airborne uranium concentration was found to be higher for higher particle sizes in all areas. Average AMAD for different locations varied from 5.8 to 7.7 mum with GSD from 1.63 to 6.73 and the ratio of calculated ALI to standard varies from 1.13 to 1.55.

Radiological characterisation of synthetic rutile using HPGe gamma spectrometry.

This paper discusses the radiological characterisation of synthetic rutile, which is the source material for the production of titanium. The natural radioactivity due to uranium ((238)U), thorium ((232)Th) series radionuclides and potassium ((40)K) was measured in synthetic rutile samples of a production plant in Tamil Nadu, India. n-type high-purity germanium-coupled gamma spectrometry was used for the analysis. It is observed that thorium is more abundant than any other radionuclide, which is due to the monazite present in the primary sand. The activity index (I) evaluated from the radioactivity concentrations of (226)Ra, (232)Th and (40)K of the analysed samples is found to be well below the recommended levels. This study shows that the use of synthetic rutile from Tamil Nadu, India, for the manufacture of building materials will not pose any increased radiation exposure to the public beyond the dose criterion of the European Union.

Natural radioactivity in roadside soil along Jamshedpur-Musabani road: a mineralised and mining region, Jharkhand and associated risk.

The specific activity and the gamma radiation dose rates due to naturally occurring radioactive materials ((238)U, (232)Th and (40)K) were determined in 26 roadside surface soils along Jamshedpur-Musabani road-a mineralised and mining region, using high-resolution gamma-ray spectrometry. The concentrations of (238)U, (232)Th and (40)K in the soil samples were found to be in the range of 16.6 +/- 0.6-390.5 +/- 1.6, 24.1 +/- 0.7-148.2 +/- 2.1 and 85.9 +/- 3.8-881.6 +/- 22.4 Bq kg(-1), respectively. The annual effective dose equivalent was found to be in the range of 0.04-0.32 mSv y(-1) with an average value of 0.13 mSv y(-1). The excess cancer risk is in the range of 0.16 x 10(-3)-1.22 x 10(-3) with an average value of 0.49 x 10(-3).