Rajagopal Venkatesan

Rajagopal Venkatesan
Indira Gandhi Centre for Atomic Research | IGCAR · Radiological Safety Division

About

69
Publications
7,420
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950
Citations
Citations since 2016
19 Research Items
505 Citations
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100

Publications

Publications (69)
Conference Paper
The cover gas region of sodium cooled fast reactors is always being subjected to intense ionization radiation field apart from radioactive aerosols and gases. The radiation produces significant ionization of the medium resulting in large amount of bi-polar ions. The acquisition of electrical charge by sodium aerosols in cover region under bipolar i...
Chapter
Computed tomography (CT) is one of the measuring techniques for the quantification of variation in material density. Variation in material density causes a change in the attenuation coefficient of the reconstructed image. At RESD, IGCAR, an indigenously developed single source and single HPGe detector based, first-generation Gamma-ray computed tomo...
Article
Full-text available
In this work, we simulate the dispersion of oil-fire aerosols from the accident at Abqaiq oil processing facility in Saudi Arabia during 14–16 September 2019 using the Lagrangian dispersion model FLEXPART-WRF (version 3.1) to investigate the sensitivity of local and nonlocal turbulence parameterization schemes on the dispersion dynamics. The Weathe...
Article
Full-text available
In the unlikely event of core disruptive accident in sodium cooled fast reactors, the reactor containment building would be bottled up with sodium and fission product aerosols. The behavior of these aerosols is crucial to estimate the in-containment source term as a part of nuclear reactor safety analysis. In this work, the evolution of sodium aero...
Article
The importance of wave evolution and necessity for reliable prediction in coastal environments is widely recognized in many ocean engineering applications. Numerical wave models developed for limited area forecast can predict ocean waves fairly well upon imposing realistic boundary conditions from measurements. The forecast quality wherein depends...
Article
Online Nuclear Emergency Response System (ONERS) is a GIS based Decision Support System developed for the management of Off-Site Nuclear Emergencies at Nuclear Power Plant (NPP) sites in India. As part of this development, the FLEXPART model is modified to compute atmospheric dispersion using observations from the local meteorological tower for the...
Article
Full-text available
A study was carried out in the coastal waters of Kalpakkam with the objectives to evaluate the seasonality in hydrobiological parameters in surface and bottom waters, and assess the anthropogenic stress and monsoonal flux on a spatiotemporal scale. The study covered an area of approximately 100 km2 in the coastal environment. Relatively high values...
Article
Estimation of radiation dose using materials available at the exposure site is very challenging. Quartz, the main constituent of building materials, is radiation-sensitive and has been widely used for this purpose. Extraction of quartz from the building materials is an essential step towards dose estimation. In this work, five methods based on two...
Article
Full-text available
A dense bloom of Protoperidinium steinii was observed in the backwaters adjoining the western Bay of Bengal, Kalpakkam coast, which might be the first report for the world oceans. The brownish-red bloom appeared on 2nd October 2019, and it was monitored on alternate days up to 14th October. Surface water temperature was about 27.5°C and salinity wa...
Article
Full-text available
In this work, the analysis of the long-term environmental radiation monitoring data collected within the Department of Atomic Energy site, Kalpakkam using gamma monitors such as GammaTRACERS (GTs) from 2013 to 2018 and Autonomous Gamma Dose Loggers (AGDLs) located in the site boundary at distances from 1.25 to 2.5 km from 2016 to 2018 are presented...
Article
Full-text available
In this article, we formulate Monin–Obukhov similarity theory (MOST)-based relationships, for normalized standard deviations of wind velocity components under the local scaling framework, and investigate their applicability under stable and highly stable atmospheric conditions. We used the fast response data collected using an ultrasonic anemometer...
Article
Online Nuclear Emergency Response System (ONERS) is a Decision Support System (DSS) developed for the management of Off-Site Nuclear Emergencies for Nuclear Power Plant sites of India. In this work, ONERS is incorporated with a module ‘Time-Dependent Source term (TDS)' for real-time online plume dispersion and radiological consequence assessments u...
Poster
Full-text available
In this work, a mechanistic fission gas release model is developed, based on the grain boundary diffusion and percolation phenomena. The model developed is an extension of the Millet et al.’s [1] grain boundary percolation model and is capable of calculating the fission gas release for the stable as well as unstable isotopes. The model is validated...
Article
In this study, we analyze the performance of the Gaussian model with improved dispersion parameters and a Lagrangian dispersion model with coupled Langevin equation under low wind speed conditions. We used data collected from Hanford-67 tracer experiment for comparison of the crosswind plume standard deviation simulated by these models. The study m...
Article
In this article, submesoscale motions observed using SODAR and fast response anemometer data during sea breeze hours is studied. SODAR data indicated the presence of waves with period ~ 30 min during the sea breeze hours. The observations are further verified by spectral analysis of sonic anemometer data using wavelet and FFT techniques. The analys...
Article
Full-text available
Wind Energy is one of the most important sources of renewable energy. There is a need to develop the availability of wind energy in the field where there is no measured wind velocity information. For this type of situation, it seems to be necessary to predict the wind energy potential using such as wind speed using artificial neural network (ANN) m...
Article
In this study, radiation doses and lifetime attributable health risk to the members of public in a 40-km impact zone around the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) were assessed for the airborne releases that occurred during 11–31 March 2011 from the loss of coolant accident associated with the east Japan earthquake and tsunami event. Hi...
Article
Full-text available
The objective of this study is to examine the impact of assimilation of conventional and satellite data on the prediction of a severe cyclonic storm that formed in the Bay of Bengal during November 2008 with the four-dimensional data assimilation (FDDA) technique. The Weather Research and Forecasting (WRF ARW) model was used to study the structure,...
Article
The severe accident in Fukushima Dai-ichi Nuclear Power plant (FD-NPP) on 11th March?11 due to earthquake and Tsunami had led to release of large activity in to the environment. To study the activity deposition through air route in an 80-km radius over the sea surface around the FDNPP numerical simulations were carried out with FLEXPART-WRF regiona...
Article
In this paper a turbulence kinetic energy (TKE) based empirical formulation for turbulent diffusion is developed from ultra sonic anemometer measurements at a tropical coastal site Kalpakkam situated on the southeast coast of India. The diffusivity relationship is validated against an independent observation from SODAR. This formulation for turbule...
Article
Bimodal plume shapes are occasionally observed in the series of tracer release experiments conducted at Hanford known as Hanford 67. These particular cases have not been studied so far. A possible reason for the bimodal shape could be the nocturnal submesoscale meandering of wind over the valley terrain. This study investigates the ability of state...
Article
The importance of wave evolution and necessity for reliable prediction in coastal environments is widely recognized in many ocean engineering applications. Numerical wave models developed for limited area forecast can predict ocean waves fairly well upon imposing realistic boundary conditions from measurements. The forecast quality wherein depends...
Article
Coherent roll structures are often observed in the atmospheric boundary layer during strong wind shears and pre-convective situations. Data collected from in situ and remote observations at a coastal site under the presence of the rolls are analyzed which confirm the typical characteristic features coherent roll structures. A mesoscale simulation s...
Article
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...
Article
An enhanced sea level during an extreme weather event can result from cumulative effects of reduced sea-level pressure, storm surge, tidal effects and wave induced setup. A numerical experiment was conducted to evaluate sensitivity of model resolution and bottom slope on wave induced setup for an arbitrary coast. Further, an assessment of wave setu...
Article
An enhanced sea level during an extreme weather event can result from cumulative effects of reduced sea-level pressure, storm surge, tidal effects and wave induced setup. A numerical experiment was conducted to evaluate sensitivity of model resolution and bottom slope on wave induced setup for an arbitrary coast. Further, an assessment of wave setu...
Conference Paper
Site specific meteorological observations are essential in understanding Boundary Layer turbulence and Atmospheric Dispersion for impact assessment studies. At the tropical coastal site Kalpakkam the monsoon flow field largely influences the transport of pollutants and often meso-scale sea breeze alters this flow pattern. In order to understand the...
Article
An Improvised Nuclear Device or nuclear bomb of yield 10 kiloton to 20 kiloton explodes in any major city due to terrorism or any other reason can cause catastrophic damages on the building's and other infrastructures and also shutting down of critical life-safety systems. The explosion may produce blast overpressure, thermal radiation and harmful...
Article
The performance of a triple-nested mesoscale atmospheric model (MM5) implemented in the Online Nuclear Emergency Response System (ONERS) at Kalpakkam on southeast coast of India is evaluated. Real-time atmospheric model predictions are used to compute radiological plume dispersion in the mesoscale ranges using Lagrangian particle models. About 280...
Article
Continuous dose rate recorded by the network of environmental monitoring stations at Kalpakkam is analysed for estimating the site dose profile with respect to the local climatology. The gamma dose rate recorded comprises of the natural background as well as the dose due to the designed release of Ar-41 gaseous activity from Madras Atomic Power Sta...
Article
Atmospheric surface layer meteorological observations obtained from 20 m height meteorological tower at Mangalore University campus, situated along the west coast of India, are used to estimate the surface layer scaling parameters of roughness length (zo) and drag coefficient (CD) and the surface layer fluxes of sensible heat and momentum. These pa...
Article
Full-text available
Satellite Remote Sensing data and spatially generated field observations provide crucial parameters in numerical atmospheric models to define realistic surface boundary conditions. In this study two important parameters i.e., vegetation and soil categories are generated for application in the PSU/NCAR mesoscale model MM5 for realistic representatio...
Article
A portable energy-specific fluence monitor is developed for field monitoring as well as to serve as stand-alone data acquisition system to measure dose rate due to routine releases at various locations in and around Nuclear Power Reactors. The data from an array of such monitors deployed over a region of interest would help in evolving a methodolog...
Article
A mesoscale atmospheric model PSU/NCAR MM5 is used to provide operational weather forecasts for a nuclear emergency response decision support system on the southeast coast of India. In this study the performance of the MM5 model with assimilation of conventional surface and upper-air observations along with satellite derived 2-d surface wind data f...
Article
Atmospheric surface layer meteorological observations obtained from 20-m-high meteorological tower at Mangalore, situated along the west coast of India are used to estimate the surface layer scaling parameters of roughness length (z o) and drag coefficient (C D), surface layer fluxes of sensible heat and momentum. These parameters are computed usin...
Article
Full-text available
Numerical ocean models are considered today as an essential tool to predict spurt in the sea level rise and associated inland extent of flooding that could be generated by a cyclonic storm crossing any coastal stretch. For this purpose, the advanced two-dimensional depth-integrated (ADCIRC-2DDI) circulation model based on finite-element formulation...
Article
Meteorological measurements were carried out at North Chennai semi rural area during pre-monsoon period as a part of an air quality study program. Analysis of the data showed the effects of coastal terrain namely the land-sea breeze circulation, temperature cooling during the sea breeze, difference in onset times at these sites etc. Sea breeze onse...
Article
Full-text available
Radiological impact due to hypothetical air-borne effluent releases for an upcoming fast reactor (PFBR), at a tropical coastal site in Kalpakkam is studied using the HYSPLIT dispersion model. Short range air dispersion simulations are conducted with HYSPLIT for a weakly forced synoptic condition on 3rd March, 2008 with three turbulent diffusion met...
Article
Full-text available
Detailed measurements were carried out in the Marine Atmospheric Boundary Layer (MABL) during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) which covered both Arabian Sea and Bay of Bengal during March to May 2006. In this paper, we present the meteorological observations made during this campaign. The latitudinal variati...
Article
This paper describes the implementation of meteorological measurement facility by installing 50 m tall towers at Kalpakkam for atmospheric dispersion studies. Though nothing novel could apparently be attributed to the idea of writing an article on the tower, the cost-effective structural design, portability-recoverability, in-house design of the si...
Article
The sensitivity of mesoscale simulations of land and sea breeze circulation on the south east coast in the Chennai region of India to boundary layer turbulence parameterizations is studied using the community based PSU/NCAR mesoscale model MM5. High-resolution simulations are carried out with nested domains. Four widely used boundary layer turbulen...
Article
The Andhra severe cyclonic storm (2003) is simulated to study its evolution, structure, intensity and movement using the Penn State/NCAR non-hydrostatic mesoscale atmospheric model MM5. The model is used with three interactive nested domains at 81, 27 and 9 km resolutions covering the Bay of Bengal and adjoining Indian Peninsula. The performance of...
Chapter
The Andhra severe cyclonic storm (2003) is simulated to study its evolution, structure, intensity and movement using the Penn State/NCAR non-hydrostatic mesoscale atmospheric model MM5. The model is used with three interactive nested domains at 81, 27 and 9 km resolutions covering the Bay of Bengal and adjoining Indian Peninsula. The performance of...
Article
Abstract The sensitivity of mesoscale simulations of land and sea breeze circulation on the south east coast in the Chennai region of India to boundary layer turbulence parameterizations is studied using the community based PSU/NCAR mesoscale model MM5. High-resolution simulations are carried out with nested domains. Four widely used boundary layer...
Article
Atmospheric dispersion of sodium oxide aerosols due to hypothetical sodium fire scenarios from nuclear facilities at Kalpakkam, is studied in a short range of 5 km. The release inventory of sodium oxide aerosols is arrived based on the experimental results of sodium fires and HAARM (Heterogeneous aerosol agglomeration revised model) code. The groun...
Article
Full-text available
A simulation study of the sea breeze circulation and thermal internal boundary layer (TIBL) characteristics has been carried out at the tropical site Kalpakkam on the east coast of India, for operational atmospheric dispersion prediction. The community based PSU/NCAR MM5 Meso-scale meteorological model is used for the study. Three cases on typical...
Article
Full-text available
An operational atmospheric dispersion prediction system is implemented on a cluster supercomputer for Online Emergency Response at the Kalpakkam nuclear site. This numerical system constitutes a parallel version of a nested grid meso-scale meteorological model MM5 coupled to a random walk particle dispersion model FLEXPART. The system provides 48-h...
Article
Meteorological condition in coastal regions is diurnally variable and spatially heterogeneous due to complex topography, land–sea interface, etc. A wide range of dispersion conditions is possible on a given day in the coastal regions. In case of inadvertent accidental situations, though unlikely, it would be necessary to examine the potentially sev...
Article
Ground level concentration and sky-shine dose due to radioactive emissions from a nuclear power plant at a coastal site have been estimated using the standard Gaussian Plume Model (GPM) and the modified GPM suggested by Misra (Atmospheric Environment 14 (1980) 397), which incorporates fumigation effect under sea breeze condition. The difference in...
Article
Full-text available
Atmospheric boundary layer observations are conducted at a coastal site during a transition phase from winter to summer season over the Indian peninsula. Thermal Internal Boundary Layer (TIBL) characteristics in presence of an off-shore and a weakly influenced on-shore synoptic wind are examined with the help of measurements carried out with a mini...
Article
Full-text available
Time series of soil surface and subsurface temperatures, soil heat flux, net radiation, air temperature and wind speed were measured at two locations in Kalpakkam, coastal southeast India. The data were analysed to estimate soil thermal diffusivity, thermal conductivity, volumetric heat capacity and soil heat flux. This paper describes the results...
Article
A numerical two-dimensional-mesoscale model with a level 1.5 closure scheme for turbulence is described. The model is used to simulate the boundary layer over coastal complex terrain. Meteorological data available from the Øresund land-sea-land terrain experiment are used to study the performance of the model. The model could simulate generally obs...
Article
Atmospheric dispersion code system SPEEDI (System for Prediction of Environmental Emergency Dose Information) has been applied to simulate the field experiments conducted over a complex terrain. A diagnostic mass-consistent wind field model of the code system simulates the flow over an isolated hill using the routinely measured data from sodars and...
Article
Similarity relationships for the atmospheric surface layer are used to estimate wind and turbulence parameters and are compared against the data from a three-axis monostatic SODAR. The daytime surface heat flux is estimated using energy budget method which takes as input the routinely measured wind, temperature and cloud cover. Heat flux is also de...
Article
As the neutron penetrations through a bulk shield weakens the shield causing excessive flux levels, experimental investigation of such a streaming is of vital importance. In the present work, a series of measurements of fast neutron streaming through L-shaped, air-filled, rectangular concrete duct was conducted using Am-α-Be neutron source. The neu...
Article
Experiments that measure the transport of fission neutrons through gadolinium, samarium and boron loaded slab shields were carried out using a Cf252 source. The effectiveness of rare earths in comparision to boron as suitable additives in concrete is investigated. A NE-213 liquid scintillation detector with pulse shape discrimination to simultaneou...
Article
Measurements on the neutron and γ-ray attenuation in multi-legged air filled ducts have been carried out using a Cockroft-Walton type neutron generator. The measured spectra were obtained with an NE-213 liquid scintillator using pulse shape discrimination to resolve neutron and γ-ray pulse height data and using a spectral unfolding code to convert...
Article
Measurements on the neutron andγ-ray attenuation in multi-legged air filled ducts have been carried out using a Cockroft-Walton type neutron generator. The measured spectra were obtained with an NE-213 liquid scintillator using pulse shape discrimination to resolve neutron andγ-ray pulse height data and using a spectral unfolding code to convert th...

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