H.M. Somashekarappa

Distribution of some natural and artificial radionuclides in Mangalore environment of South India

Abstract The activities of 40 K, 226 Ra, 228 Ra, 210 Po, 210 Pb, 137 Cs and 90 Sr were determined in a number of natural samples in the environment of Mangalore, South India where large-scale industrial activities are envisaged. Well-established nuclear techniques were employed to measure the activities and wherever necessary radiochemical methods were also followed. The measurement of transfer coefficients indicated that the uptake of 226 Ra, 228 Ra and 210 Pb in paddy is higher than that in vegetables. The measured activity ratios of 210 Po: 210 Pb and 228 Ra: 226 Ra in soil samples suggest the existence of equilibrium between the corresponding radionuclides in normal background areas and disequilibrium in high background areas. The intake of radionuclides by the population and the internal dose were estimated. The annual internal effective dose for the population is found to be 341 μSv year −1 which mainly arises from 40 K and 210 Pb.

226Ra, 40K and 7Be activity concentrations in plants in the environment of Kaiga, India

Leaves, stem and bark samples from several plant species were collected from tropical forest of Kaiga, in the west coast of India where two nuclear power reactors of 220 MW each have just been commissioned and another two are under construction, and analysed for their (226)Ra, (40)K and (7)Be concentrations. The activities of (226)Ra and (40)K in plants were found to vary in the range BDL-13.2 and 12.0-797.3 Bq kg(-1), respectively. Plants show significant (7)Be activity in leaves, the activity varies in 72.5-1,060.8 Bq kg(-1). Stem and bark of plants show higher levels of (226)Ra and (40)K when compared to leaves. Soil-to-plant transfer factor for (226)Ra and (40)K were found to vary in the range BDL-0.37 and 0.09-5.61, respectively for different plants. The concentration of (226)Ra and (40)K in leaves depends on the age of the leaves.

Distribution of some natural and artificial radionuclides in the environment of coastal Karnataka of south India

Coastal Karnataka, which is an important region of the south-west coast of India, is poised to become a region of major industrial activity with the construction of nuclear and thermal power stations, oil refineries and petrochemical complexes. This is in addition to existing chemical and fertilizer factories and a host of other industries. Systematic studies on radiation levels and radionuclide distributions in the environment of this region were undertaken to provide baseline data on the radiation levels for future assessment of the impact of these industrial activities and to throw light on the basic aspects of transportation of radionuclides in the environment and their uptake by vegetation species. The activities of 40K, 226Ra, 210Po, 210Pb, 228Ra, 137Cs and 90Sr were determined in a number of environmental samples of the region by employing well established nuclear techniques and standard radiochemical methods. The internal dose to the population of the region from ingestion of different radionuclides was estimated. The results of these systematic investigations, which form the first ever report on the radionuclide distribution of coastal Karnataka, are presented and discussed in this paper.

Bioindicators in the tropical forest of Kaiga environment

Abstract Investigations on the natural and artificial fallout radionuclides 210 Po and 137 Cs and the primordial radionuclide 40 K in the prominent tree species of Western Ghat tropical forests near Kaiga have been carried out as a part of baseline background radiation studies in the environment of Kaiga where nuclear power reactors are being installed. The prominent tree species of the region Tectona grandis L.f. and Terminalia paniculata Roth., and the commonly available epiphytic plant species Pterobryopsis tumida (Hook.) Dix. and Cymbidium aliofolium (Lo) Swartz. were chosen and concentrations of 40 K, 210 Po and 137 Cs were measured employing well-established nuclear techniques. The different parts of Cumbidium aloifolium (Lo) Swartz. such as leaves, stem, etc. were analysed to understand the absorption mechanism of fallout radionuclides. From a careful analysis of the results, the epiphytic plant species are identified as bioindicators to monitor fallout radionuclides.

Estimation of radionuclides concentration and average annual committed effective dose due to ingestion for some selected medicinal plants of South India

Abstract Eight medicinal plants and soil samples from the Malnad area of Karnataka in South India (N 13°29′35.4″; E 75°18′02.4″) were analysed for activity concentrations of natural and artificial radionuclides using HPGe gamma spectrometry. The average annual committed effective dose (AACED) due to the ingestion of radionuclides from medicinal plants were also estimated. The activity concentrations of 226Ra, 210Pb, 232Th, and 40K were found to vary in the range of 32.27–60.12 Bqkg−1, 56.09–160.56 Bqkg−1, 49.61–98.46 Bqkg−1, and 241.57–712.85 Bqkg−1, respectively, in the soil samples and 2.66–11.27 Bqkg−1, BDL to 87.03 Bqkg−1, 2.42–8.72 Bqkg−1, and 93.79–6831.40 Bqkg−1, respectively, in the medicinal plants corresponding to the soil samples. The activity concentration of artificially produced radionuclide 137Cs was BDL to 12.34 Bqkg−1 in the soil and it was below detectable level (BDL) in all the plant samples. The soil to plant transfer factors (TF) varied from 0.07 to 0.27, BDL to 0.80, 0.04 to 0.13 and 0.17 to 23.80, respectively, for 226Ra, 210Pb, 232Th, and 40K. The AACED due to the ingestion of radionuclides from the medicinal plants varied from 0.0075 to 0.1067 mSvy−1. The AACED values reported in this study are much below the world average value of 0.30 mSvy−1 for an individual. This indicates that there is no radiological health risk in using these plants for medicinal purposes. This study may also contribute data on local medicinal plants to formulate regulations related to radiological healthcare.

Atmospheric radon levels and its emanation rate in the environment of Kaiga

Abstract A systematic study of atmospheric radon levels and of radon emanation rates was conducted in the environment of Kaiga on the south-west coast of India where the installation of nuclear power reactors is in progress. 222 Rn emanation rates were estimated employing the accumulating chamber method and were found to vary from 5.6 to 62.9 mBq m −2 s −1 with a geometric mean of 30.0 mBq m −2 s −1 . The atmospheric concentrations were estimated using CR-39 solid state nuclear track detectors (SSNTDs) and found to vary from 4.7 to 27.9 Bq m −3 with a geometric mean of 13.4 Bq m −3 . The results show a strong correlation between emanation rate and atmospheric concentration while showing a poor correlation between 226 Ra concentration in surface soil and atmospheric concentration of 222 Rn. The results are also compared and discussed in the light of relevant literature reported for other environments.

Prominent artificial radionuclide activity in the environment of coastal Karnataka on the southwest coast of India

Studies on radiation level and radionuclide distribution in the environment of coastal Karnataka were undertaken to provide baseline data for the future assessment of the impact of the nuclear and thermal power stations that are being set up in the region and to understand the behaviour of radionuclides in the environment. As part of the programme the concentrations of two important artificial radionuclides, namely 90Sr and 137Cs, have been measured in a number of environmental samples. The concentration of 90Sr is very low in most of the samples. Among the samples analysed for the concentration of 137Cs, soil samples showed elevated levels of activity in some sampling stations. Among the vegetables, brinjal (Solanum melongena. L) showed considerable activity. The internal dose due to intake of 90Sr through diet was 0.42 microSv year(-1) for the vegetarian population and 0.32 microSv year(-1) for the non-vegetarian population. The internal dose due to dietary intake of 137Cs was found to be 0.34 microSv year(-1) and 0.26 microSv year(-1) respectively for the vegetarian and non-vegetarian population. The results are discussed in the light of the literature values reported for other environs of India and abroad and appropriate inferences are drawn.

Preparation and characterization of (125)i labeled bovine serum albumin.

Bovine serum albumin is a model protein, which has been conventionally used as protein standard and in many areas of biochemistry, pharmacology and medicine. Radioiodination procedure for bovine serum albumin employing chloramine-T as an oxidant with slight modification was evaluated critically to establish the optimal conditions for the preparation of radiolabeled tracer ( 125 I-BSA) with required specific activity without impairing the immune reactivity and biological activity. Optimized radioiodination procedure involving 10 µg of chloramine-T along with 20 µg of sodium metabisulphite with 60 seconds incubation at 2° yielded 125 I-BSA with high integrity.

Experimental response function of a 3 in×3 in NaI(Tl) detector by inverse matrix method and effective atomic number of composite materials by gamma backscattering technique.

Response function of a widely used 3in×3in NaI(Tl) detector is constructed to correct the observed pulse height distribution. A 10×10 inverse matrix is constructed using 7 mono-energetic gamma sources ((57)Co, (203)Hg, (133)Ba, (22)Na, (137)Cs, (54)Mn and (65)Zn) which are evenly spaced in energy scale to unscramble the observed pulse height distribution. Bin widths (E)(1/2) of 0.01 (MeV)(1/2) are used to construct the matrix. Backscattered photons for an angle of 110° are obtained from a well-collimated 0.2146GBq (5.8mCi) (137)Cs gamma source for carbon, aluminium, iron, copper, granite and Portland cement. For each observed spectrum, single scattered spectrum is constructed analytically using detector parameters like FWHM, photo-peak efficiency and peak counts. Response corrected multiple scattered photons are extracted from the observed pulse height distribution by dividing the spectrum into a 10 ×1 matrix. Saturation thicknesses of carbon, aluminium, iron, copper, granite and Portland cement are found out. Variation of multiple scattered photons as a function of target thickness are simulated using MCNP code. A relationship between experimental and simulated saturation thicknesses of carbon, aluminium, iron and copper is obtained as a function of atomic number. Using this relation, effective atomic numbers of granite and Portland cement are obtained from interpolation method. Effective atomic numbers of granite and Portland cement are also obtained by theoretical equation using their elemental composition and comparing with the experimental and simulated results.

Experimental and simulated study of detector collimation for a portable 3″ × 3″ NaI(Tl) detector system for in-situ measurements

Abstract The effect of detector collimator and scatterer thickness on multiple Compton backscattered gamma photons is studied. Gamma photons from a 137Cs source of 5.8mCi, is allowed to fall on Carbon, Aluminium, Iron and Copper targets and the scattered photons are detected by a properly shielded 76mm×76mm NaI(Tl) scintillation detector located at 90° to the incident beam. To extract the contribution of multiple scattered photons from the measured spectra, single scattered distribution is remodelled analytically. The thickness at which the multiple scattered photons saturate is determined for different detector collimator apertures and scatterer thicknesses. The variation of saturation thickness, Signal-to-Noise (S/N) ratio, Multiple Scattering Fraction (MSF) for different materials and collimator sizes are studied and compared with the available literature. Monte Carlo simulated calculations using MCNP code supports the present experimental work.