J. S. Dubey

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.

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.

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).

Source identification of particulate matter and associated intake of elements through inhalation in an industrial area of Odisha, India

Particulate matter concentrations were measured in an industrial region in the Ganjam district of Odisha. The average levels of suspended particulate matter (SPM) were measured to be 142 ± 8 and PM10 of particulate matter with a size of less than 10 micrometers (PM10) to be 50 ± 15 μg m−3. Out of the 14 elements determined, Ca, Na, Mg, Fe, and K contributed more than 95% of the total weight. In enrichment factors, the trace elements, i.e., Zn, Pb, Cd, and Hg were observed to be highly enriched in the SPM and PM10. Factor analysis indicates that more than 75% of the variance was due to five component factors, which have eigenvalues greater than 1. Intake of elements through inhalation route to adults has been estimated.

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).

Effect of Specimen Geometry, Orientation and Temperature on the Impact Toughness of Zr-2.5Nb Pressure Tube

Impact toughness of Zr-2.5Nb pressure tube material was evaluated as a function of specimen geometry, orientation and test temperature. Two types of samples were used. Curved impact specimens were machined directly from the tube section thereby retaining the pressure tube curvature and flat impact specimens were machined from a flattened tube section subjected to stress relieving treatment. In both the cases the specimen thickness was the actual pressure tube thickness that is 3.5 mm and the other dimension of the impact specimen was 55 mm × 10 mm. The tests were carried out for both as-received and hydrided pressure tubes between room temperature and 300 °C. As the Zr-2.5Nb pressure tube material is anisotropic, the studies were also carried out using specimens with crack growth either along axial or along transverse direction of the tube. The paper describes the results generated and discusses the materials impact toughness behaviour under different conditions.

Optimization of 210Po estimation in environmental samples using an improved deposition unit

Abstract Measurement of 210Po in environmental matrices is important due to its very high specific activity, present in every compartment of the environment due to a daughter product of uranium (238U), accumulative and highly toxic in nature. Conventional method for 210Po estimation is by auto-deposition onto both sides of a silver disc followed by alpha spectrometry of both the sides. A new deposition unit having the facility to hold the silver disc and magnetic stirring bar has designed and fabricated for 210Po estimation in which only one side is counted. In the conventional method, the total activity is distributed to the both sides of the silver disc and more counting time is required whereas in the improved deposition unit, only one side contain all the activity so that one time counting is required with better statistical significance. The same has been observed in spike recovery and water sample assessment. The tracer recovery in the conventional method was 72% – 88% and 70% – 85% whereas for the new deposition the recovery is 87% – 99% and 78% – 94% for spike recovery study and environmental samples, respectively. Certified tracers were analysed for the assurance of the reliability of the method and the results were in good agreement with the recommended value with a relative error <20%. The MDA of the method is 1.5 mBq for the estimation of 210Po at 3σ confidence level, 86400 s. counting time and 100 ml of water sample, taking the detector efficiency and chemical yield into consideration. The results obtained from both the methods were compared statistically. χ2 test, repeatability parameters, relative bias measurement and linearity test was performed for both the methods. The % difference between the two methods in terms of linearity is 0.2%. From the χ2 test it can be concluded that the measured data by two methods falls within 99% confidence interval. The modified deposition unit enhance the statistical significance, reduce the counting time, improved detection level, accuracy and precision and more suitable for determination of 210Po in environmental samples as the levels in various environmental matrices is very low and close to the method detection level.

Fracture Behaviour of Type 304LN Stainless Steel and its Welds

SA312 type 304LN stainless steel material, having closer control over impurities and inclusion content, is the intended piping material in the Advanced Heavy Water Reactors. Deformation, fatigue and fracture behaviour of this material and its weldments have been characterized at ambient temperature and at 558K. The details of the fractographic investigations and stretch zone width measurements are also discussed. The base metals shows high initiation toughness (>500 kJ/m2 ) and large tearing modulus at ambient and operating temperatures. Shielded Metal Arc Welding (SMAW) weld metal shows much much reduced initiation toughness and tearing resistance in comparison to base metal and Gas Tungsten Arc Welding (GTAW) welds. This is attributed to larger density of second phase inclusions in the SMAW weld metal. SZW measurements give a good alternate estimate of the toughness of the materials. Fatigue crack growth rate in SMAW weld metal was found to be comparable to base metal at higher load ratios.Copyright