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The activity concentration of Ra, Th and K in brick samples used in Tiruvannamalai District of Tamilnadu has been determined using gamma ray spectrometry. The activity concentration ranges from BDL to 16.02 Bq kg, 17.86 to 120.19 Bq kg, 240.09 to 481.35 Bq kg for Ra, Th, and K, respectively. The concentration of these radionuclides is compared with reported data from other countries. The radium equivalent activity (Raeq), absorbed gamma dose rate (DR), annual effective dose rate (HR), annual gonadal dose equivalent (AGDE), criteria formula (CF), representative level index (RLI), activity utilization index (AUI), gamma index (Iγ), alpha index (Iα), the external hazard (Hex), and internal hazard (Hin) indices are calculated for the measured samples to assess the radiation hazards due to the use of these materials in the construction of dwellings. Multivariate statistical techniques (Pearson correlation, principal component analysis and cluster analysis) are used to study the relation between radionuclides and radiation hazards. The treatment of 14 radioactive variables sampled at 32 bricks by the factor and cluster analyses provided a possible interpretation of the collective data. The spatial distribution pattern of radionuclides has been depicted through the Kriging method using MapInfo software.

Using γ spectrometry, the concentration of the naturally occurring radionuclides (226)Ra, (232)Th and (40)K has been measured in soil, sand, cement, clay and bricks, which are used as building materials in Tiruvannamalai, Tamilnadu, India. The radium equivalent activity (Raeq), the criterion formula (CF), indoor gamma absorbed dose rate (DR), annual effective dose (HR), activity utilization index (AUI), alpha index (Iα), gamma index (Iγ), external radiation hazard index (Hex), internal radiation hazard index (Hin), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the building materials. From the analysis, it is found that these materials used for the construction of dwellings are safe for the inhabitants. The radiological data were processed using multivariate statistical methods to determine the similarities and correlation among the various samples. The frequency distributions for all radionuclides were analyzed. The data set consisted of 15 measured variables. The Pearson correlation coefficient reveals that the (226)Ra distribution in building materials is controlled by the variation of the (40)K concentration. Principal component analysis (PCA) yields a two-component representation of the acquired data from the building materials in Tiruvannamalai, wherein 94.9% of the total variance is explained. The resulting dendrogram of hierarchical cluster analysis (HCA) classified the 30 building materials into four major groups using 15 variables., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The present paper describes a detailed study on the distribution of radionuclides along Chavara - Neendakara placer deposit, a high background radiation area (HBRA) along the Southwest coast of India (Kerala). Judged from our studies using HPGe gamma spectrometric detector, it becomes evident that Uranium ((238)U), Thorium ((232)Th) and Potassium ((40)K) are the major sources for radioactivity prevailing in the area. Our statistical analyses reveal the existence of a high positive correlation between (238)U and (232)Th, implicating that the levels of these elements are interdependent. Our SEM-EDAX analyses reveal that titanium (Ti) and zircon (Zr) are the major trace elements in the sand samples, followed by aluminum, copper, iron, ruthenium, magnesium, calcium, sulphur and lead. This is first of its kind report on the radiation hazard indices on this placer deposit. The average absorbed dose rates (9795 nGy h(-1)) computed from the present study is comparable with the top-ranking HBRAs in the world, thus offering the Chavara-Neendakara placer the second position, after Brazil; pertinently, this value is much higher than the World average. The perceptibly high absorbed gamma dose rates, entrained with the high annual external effective dose rates (AEED) and average annual gonadal dose equivalent (AGDE) values existing in this HBRA, encourage us to suggest for a candid assessment of the impact of the background radiation, if any, on the organisms that inhabit along this placer deposit. Future research could effectively address the issue of the possible impact of natural radiation on the biota inhabiting this HBRA.

Presently several beta emitting radionuclides are in use as brachytherapy sources, due to their inherent advantages of short-range radiation dose delivery compared to their gamma emitting counterparts. 90Y is one of the well-known hard beta-emitting radioisotopes for the therapeutic application of radioactivity. Among various other modalities, 90Y resin microsphere as a brachytherapy source has its application for liver cancer. In the present study, 90Y was recovered from 235,238U,239Pu(nfast,f)90Sr(β−)90Y using Sr selective crown ether followed by quick purification using the Ion Chromatography technique. The purified 90Y was labelled in strong cation exchange resin to form 90Y resin microsphere. Various quality control parameters, e.g., water solubility, chemical, radionuclidic purity, and half-life, were verified using Gamma spectrometry, Cerenkov, and Liquid Scintillation Counting techniques. The obtained half-life was 64.05 h, which is in excellent agreement with the literature and is indirect evidence of the very high radionuclidic purity of the sample. A rapid method for the synthesis of 90Y resin microsphere brachytherapy source is being reported for the first time after its recovery from irradiated fast reactor fuel dissolver solution. After the separation of 90Sr along with trace level impurities inside the hot cell, simultaneous purification of parent 90Sr and daughter 90Y using single-stage Ion Chromatography step takes 15–25 min only in comparison to 24 h or more time using multistage conventional Ion exchange chromatography column, which saves the separation time and in turn, increase the yield of 90Y per separation campaign. [ABSTRACT FROM AUTHOR]

This paper discusses the relation between the heavy metal and radionuclide activity concentration in beach sand samples collected from East Coast of Tamilnadu. The elemental composition in beach sands is determined by EDXRF technique. The mean concentrations of elements followed in the order of Si > Ca > Fe > Al > Mg > K > Ti > Mn > Zr > Sr > Zn > Pb > Ni > Cu > Cd > Co in the study area. A NaI(Tl) gamma-ray spectrometer has been used to determine activity concentration of 238U, 232Th and 40K in sand samples. The measured activity in the sand samples ranged from 3.0 to 1766.8 Bqkg−1, 3.0 to 8326.88 Bqkg−1 and 11 to 1434.9 Bqkg−1 for 238U, 232Th and 40K, respectively. The measured natural radioactivity concentration was compared with worldwide average values as reported by UNSCEAR. The interrelation between the natural radioactivity and heavy metal concentration is determined using Pearson correlation coefficient, factor and cluster analysis for finding existing relation between them. The results showed that there is a significant relation of heavy metals for heavy minerals which can contribute radioactivity concentration based on the correlation and factor analysis. [ABSTRACT FROM AUTHOR]

The activity concentration of 238U, 232Th and 40K were measured in the soil samples collected from Fast Reactor Fuel Cycle Facility (FRFCF) site, using high-resolution gamma-ray spectrometry. This study is aimed to establish the baseline data of naturally occurring radionuclides within the site. The average activity concentrations were found to be 416.5, 61.7 and 622.3 Bq kg−1 for 40K, 238U and 232Th, respectively. The activity concentrations and its radiological indices were evaluated and were compared with the international values reported by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The ratio of 40K/232Th and 40K /238U were calculated, which indicates the presence of 5.79 and 2.69 times more K-bearing minerals as compared with Th and U-bearing minerals in the soil samples, respectively. The study provides baseline information on concentration of radionuclides and background radiological assessment of the FRFCF site. [ABSTRACT FROM AUTHOR]

Kerala is listed among the six highest background radiation areas of the world. The west coast of Kerala is very well studied. However, no data is available regarding the high ranges. This study reports measurement of terrestrial concentration of radionuclides in Wayanad district (altitude range 700-2100 m above mean sea level), a known tourist place of Kerala, India having a sizeable tribal population. Activities of K, Ra and Th in soil samples measured using gamma ray spectrometry were found to be 265 ± 334, 21 ± 15 and 39 ± 38 Bq kg respectively. Similar studies were done for rock samples. The average indoor and outdoor hazard indices were found to be 0.24 and 0.20 for soil and 0.5 and 0.4 for rocks, respectively. The indoor radon and thoron concentrations were measured using solid state nuclear track detector. The annual average radon concentration was found to be 31 Bq m and the annual average thoron concentration was 96 Bq m. Out of the samples, one house showed elevated thoron concentration with an annual average value of 621 Bq m. [ABSTRACT FROM AUTHOR]

This paper reports on the distribution of three natural radionuclides 238 U, 232 Th and 40 K in coastal sediments from Pattipulam to Devanampattinam along the East coast of Tamilnadu to establish baseline data for future environmental monitoring. Sediment samples were collected by a Peterson grab samples from 10 m water depth parallel to the shore line. Concentration of natural radionuclides were determined using a NaI(Tl) detector based γ-spectrometry. The mean activity concentration is ⩽2.21, 14.29 and 360.23 Bq kg −1 for 238 U, 232 Th and 40 K, respectively. The average activity of 232 Th, 238 U and 40 K is lower when compared to the world average value. Radiological hazard parameters were estimated based on the activity concentrations of 238 U, 232 Th and 40 K to find out any radiation hazard associated with the sediments. The radiological hazard parameters such as radium equivalent activity (Ra eq ), absorbed gamma dose rates in air ( D R ), the annual gonadal dose equivalent (AGDE), annual effective dose equivalent (AEDE), external hazard index ( H ex ) internal hazard index ( H in ), activity utilization index (AUI) and excess lifetime cancer (ELCR) associated with the radionuclides were calculated and compared with internationally approved values and the recommended safety limits. Pearson correlation, principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been applied in order to recognize and classify radiological parameters in sediments collected at 22 sites on East coast of Tamilnadu. The values of radiation hazard parameters were comparable to the world averages and below the recommended values. Therefore, coastal sediments do not to pose any significant radiological health risk to the people living in nearby areas along East coast of Tamilnadu. The data obtained in this study will serve as a baseline data in natural radionuclide concentration in sediments along the coastal East coast of Tamilnadu. [ABSTRACT FROM AUTHOR]

A study was carried out to estimate the ingestion dose for the general population residing around Kalpakkam nuclear site due to 40K activity in the fresh and cooked food samples collected from the surrounding areas. For the estimation of specific activity of 40K, food samples consisting of 31 numbers of market basket samples (MBS) and 33 numbers of duplicate diet samples (DDS) were collected, conditioned, and analyzed by gamma spectrometry. The annual effective dose (AED) received by the population was estimated based on 40K activity in the food samples, food consumption data, and ICRP model. Uncertainty associated with the estimates was quantified based on the guide to the expression of uncertainty in measurement framework approach. The 40K specific activity in MBS ranged from 10.44 ± 1.11 to 129.00 ± 13.64 Bq/kg fresh weight. Similarly, the 40K specific activity in DDS ranged from 10.85 ± 1.10 to 60.71 ± 6.15 Bq/kg fresh weight. The AED due to the ingestion of 40K estimated based on MBS was 93.81 ± 7.30 μSv/year. Similarly, the AED due to the ingestion of 40K estimated based on DDS was 33.47 ± 0.79 μSv/year among males and 26.31 ± 0.62 μSv/year among females. [ABSTRACT FROM AUTHOR]

For transport and storage of neutron sources, shielding materials like polymers and multi layer shields are used. A compact shielding design for 740 GBq portable 241Am-Be neutron source transport container using Monte Carlo technique is presented. In the design, a polymer host material with lead and natural boron (NB) as fillers is chosen as the shielding medium. Monte Carlo simulation (MCS) is performed for optimizing the quantity of fillers in the polymer. The total dose rate (TDR) on the surface of the container due to neutrons and gamma rays emanating from source as well as polymer shield, is considered as the optimization criterion. MCS studies indicate that a polymer material with 5% of lead and 1% of NB as fillers is observed to give optimized composition of polymer (OCP). Statistical factorial design analysis (FDA) technique is employed for the first time in the shielding design to investigate the impact of fillers in the polymer. FDA studies reveal that the quantity of lead has more significant impact compared to NB in the polymer. MCS results are validated by carrying out shielding experiments with high density polyethylene (HDPE) and composite polymer (CP) based containers. The computed and experimental dose rates are observed to be within ±12%. A shielding container made of OCP for the transport of 740 GBq 241Am-Be source provides 25% reduction in the volume as compared to HDPE and CP. The mass of the OCP container is lower by 18% and 26% compared to the containers made of HDPE and CP respectively. The surface dose rate of the OCP container adheres to the IAEA transport regulations. • Source term for 740 GBq 241Am-Be neutron source. • Optimization of fillers quantity in polymer by Monte Carlo simulation. • Studies on impact of fillers in polymer by factorial design analysis technique. • Validation of Monte Carlo simulations by experimental measurements. • Design of shielding container for 241Am-Be source with an optimised composite polymer. [ABSTRACT FROM AUTHOR]

The natural radioactivity in building materials collected from Polur, Tamilnadu has been determined using gamma ray spectrometer. The radiological parameters such as radium equivalent activity (Ra eq ), absorbed dose rate (D R ), annual effective dose rate (H R ), alpha index (I α ), gamma-index (I γ ), internal (H in ) and external hazard indices (H ex ) were evaluated to assess the radiation hazard for people dwelling in the study area. The calculated radiological parameters were taken for multivariate statistical analysis to study the relation between radionuclides and radiological parameters. The values obtained in the study are within the recommended safety limits, showing that these building materials do not pose any significant radiation hazard and hence the use of these materials in the construction for dwelling purpose can be considered to be safe for the inhabitants. [ABSTRACT FROM AUTHOR]

The shielded chair wholebody counting system used at IGCAR is calibrated experimentally using Masonite cut sheet phantom loaded with single radionuclide of known activity. Multiple point sources of a particular radionuclide are distributed at mid-thickness in each segment of the phantom during calibration. Though the detector can be used for the measurement of gamma photons upto 3000 keV, the experimental calibration is done only upto 1500 keV according to the requirement of measurement of fission and activation products, which emits gamma energies predominantly in the regions below 1500 keV. The expertize in numerical Monte Carlo simulation was utilized to obtain the efficiency values above 1500 keV. This paper focuses on the validation of the shielded chair counting system model using the Masonite cut sheet phantom measurements and applying the validated model to extend the energy range of the calibration upto 3 MeV. A good agreement of the theoretically simulated and experimental 137 Cs spectrum with respect to the spectral shape, counts in all the energy regions and the photopeak efficiency validated the modeling of the counting system. A mathematical function to fit the counting efficiencies with photon energies was developed and a set of fitting parameters were established so that the efficiency value of any energy upto 3 MeV can be obtained without performing experimental efficiency calibration. The efficiency values obtained from the fit were compared with experimental ones and found to be in agreement, i.e., within 8% for the 250–1500 keV energy range. The Compton scattering factors (CSFs) at different low energies due to high energy photons were also simulated. The theoretical and experimental CSFs were compared and found to be matching within ±20%. Simulations with uniform source distribution inside the Masonite phantom has shown that the current source distribution followed at IGCAR gives efficiency values within ±5% compared to that of uniform distribution. [ABSTRACT FROM AUTHOR]

For the safe disposal of High Level Waste (HLW), a common practice is to bury the sealed container called canister containing the concentrated and vitrified waste deep inside the earth surface within a rocky medium. In the event of an accidental breach of such a canister, the sealed waste may come in contact of pore water. If this happens, then the parent nuclides present in the HLW and their daughters generated by the radioactive decay reaction start migrating through the surrounding rock medium due to the combined effect of advection and diffusion. The accurate estimation of the transport of such a chain through a rock is important for radiological safety. Here, we report a finite difference based numerical simulation to address the issue. To simplify the problem, we consider the rock to be a collection of identical parallel fractures separated by porous matrices of equal width with a source at one end. A Forward Time and Centered Space (FTCS) finite difference scheme is implemented to solve the set of coupled partial differential equations that govern the transport mechanism. The scheme is validated using the methods available in the literature and subsequently it is applied to estimate the time dependent buildup of the active elements of a chain. Two independent chains each with three members are considered for simulation to address the safety related issues. [ABSTRACT FROM AUTHOR]

In this study the influence of atmospheric conditions, release height and particle size are studied on the radiological impact due to a hypothetical 15 KT nuclear explosion using the HotSpot model. Simulations show that among different parameters, the height of burst produces the highest impact on the total effective dose (TED). It is found that the maximum TED is about 4 orders higher for surface burst compared to elevated explosions. The range of impact of acute doses (TED >0.25 Sv) extends up to 10 km for neutral to stable conditions for ground releases and 5 km for unstable conditions for 600 m release. It has been found that city type terrain reduces the doses by 40% and 80% in unstable and stable conditions respectively compared to flat terrain. Simulations with different particle sizes indicate that the ground shine and TED are about twice higher for 100% RF particles compared to 50% RF particles after 0.5 km for all atmospheric conditions. The range of impact extends from 6 km for unstable to 10 km for stable conditions for both particle sizes. Larger particles lead to roughly 8 times higher ground deposited activity within 0.5 km for A to D conditions. For elevated release dose is highly sensitive to particle size parameter, almost 40 times higher compared to ground release and the range of impact extends to 10 km for 50% RF against 6 km for 100% RF. Simulations with inversion conditions suggest that an elevated inversion leads to enhanced TED especially for unstable condition (A, B, C classes) roughly by 2 factors at 1 km to 1 order at 10 km relative to no inversion and sensitivity of capping layer is lower for elevated releases. It has been found that presence of rain (10 mm.h−1) leads to higher groundshine dose by ∼1 order compared to no rain scenario. The sensitivity of washout is relatively high for elevated releases in the first 4 km range where the groundshine is at least 2 to 3 orders more compared to no rain condition and range of acute dose extends up to 8 km from 6 km in raining condition. • Influence of atmospheric conditions and source term characteristics on the radiological impact for a 15 KT hypothetical explosion studied using HotSpot. • Impact due to surface bursts is about 4 orders higher compared to elevated explosions. • Urban terrain reduces the impact by ∼40–80% under different atmospheric conditions compared to rural flat terrain. • Increase of radionuclide particle size increases ground contamination by ∼8 times in short range and impact extends to 10 km for 50% RF against 6 km for 100% RF. • Rainfall during explosion scenario increases ground contamination by 1-3 orders in the short range (3–5 km). [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the results of regional scale atmospheric dispersion simulation of accidental emission of radionuclides from the Fukushima Daiichi Reactor, Japan following the Tohoku earthquake and tsunami event on 11 March 2011. The objective was to study the temporal behaviour of plume trajectory, concentration, deposition and radiation dose pattern over an 80 km range around the reactor. The time-varying meteorological parameters during the release period were simulated with a multi-scale nested atmospheric model WRF ARW and the trajectory, plume dispersion were computed with Lagrangian Particle Dispersion models HYSPLIT, FLEXPART using the available information on accidental source term. The simulations indicated that the wind flow over Japan during the release period was driven by the large scale extra-tropical westerly waves and associated low pressure systems. In the lower levels, the flow was influenced by the local topography/sea breeze causing occasional landward wind shift on the east coast of Japan. Simulated airflow trajectories revealed that the plume stayed over the ocean by westerly winds on most days and the radioactivity dispersed over sea surface. Landward trajectories were found on a few days due to southeasterly, easterly and northeasterly flow (15–17, 19–21 March 2011) during which much of the radionuclides deposited over the land region. The hotspot of depositions occurred over east Pacific Ocean near to Japan. Over the land relatively high depositions were simulated in a narrow zone of 20 km width and 80 km length in the northwest sector in agreement with monitor data. Simulations showed wet depositions over the land to be higher than the dry depositions during 12–30 March due to occurrence of rainfall on some days. Comparison of activity deposition and air dose values with available observations confirmed that the plume pattern in a finer length scale around the site could be simulated realistically and agree with the measurements within the limitations of the uncertainty in source term. [Copyright &y& Elsevier]

Abstract: The natural radioactivity of soils at Yelagiri hills has been studied in this paper. The radioactivities of 25 samples have been measured with a NaI(Tl) detector. The radioactivity concentrations of 238U, 232Th and 40K ranged from ≤2.17 to 53.23, 13.54 to 89.89 and from 625.09 to 2207.3Bqkg−1, respectively. The measured activity concentrations for these radionuclides were compared with world average activity of soil. The average activity concentration of 232Th in the present study is 1.19 times higher than world median value while the activity of 238U and 40K is found to be lower. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity Raeq, the absorbed dose rate D R, the annual effective dose rate and the external hazard index (H ex) have been calculated and compared with the internationally approved values. The study provides background radioactivity concentrations in Yelagiri hills. [Copyright &y& Elsevier]