3. BARC

Dr. B.B. Biswas

3.1 Mathematical Analysis of Asynchronous Reactor Control Systems (Contact person: Dr. B.B. Biswas)

Nuclear reactor control systems, these days, utilize computers for processing and presentation of information. Also, in most instances a number of computers are required to achieve the required safety, control or monitoring function and these computers are generally connected over a network. Synchronous operation of these computers is preferred for satisfactory performance and appropriate design effort is necessary for achieving synchronism.

The design effort can considerably be reduced if the different computers in the system/network could operate without synchronizing. There also might be situations, e.g. due to failures in which one or more computers drop out of synchronism from an otherwise synchronously operating set of computers.

Theoretical control relevant analysis of asynchronous systems is cumbersome though. A synchronous computer system can be modeled as a shift-invariant digital system. But, modeling of the same system for asynchronous mode of operation would necessitate a very high order model or a shift-variant model. In the former situation computations are inefficient while in the later research is still at its infancy.

Study of asynchronous system represents a challenging area and can be pursued for research.

A Computer Science graduate with additional course work in the area of reactor control and linear systems theory would be capable of carrying out this study.

3.2 Estimation of Spatial Flux Distribution in AHWR using Optimum Set of In-core Detectors (Contact person: Dr. B.B. Biswas)

For on-line monitoring of core power distribution, commercial power reactors are equipped with a large number of in-core detectors. The signals from these detectors are used with some on-line software to estimate the core flux or power distribution during reactor operation. Methods exist for on-line synthesis of flux map using set of pre-computed flux modes and least-squares principles. However, these methods do not account for the dynamic behavior of the reactors as well as the past detector readings, in order to predict the spatial distribution of prompt and delayed neutrons.

Application of Kalman Filter for estimation of spatial distributions of the prompt and delayed neutron precursors in AHWR will be a unique area of research. It is also an important problem to arrive at the most suitable locations of the in-core detectors.

The reactor state variables undergo dynamic variations. The dynamical behaviors and the statistical fluctuations must be considered in order to estimate the spatial distributions of the states successfully. Literatures exist for application of Kalman Filter for estimation of neutron flux distribution for one-dimensional core with statistical fluctuations. The idea can be extended for flux mapping in AHWR with three-dimensional core model considering the dynamical behaviors of AHWR during different operational regimes. The work will be of great importance from the viewpoint of efficient control strategy in AHWR.

The work involve the following activities:

1.     Literature survey for different FMS techniques.

2.     Development of mathematical models for AHWR core and in-core detectors.

3.     Implementation of partial differential equations for the neutron diffusion equation and

identification of the core parameters including statistics of fluctuations.

4.     Realization of Kalman Filter for estimation of flux distribution.

5.     Implementation and validation of the mathematical models.

6.     Study of the effects of placement of in-core detectors.

7.     Arriving at an efficient algorithm for flux mapping and suitable location of in-core detectors.

The candidates with Post-graduate degree in Electrical Engineering with good background in under graduate subjects as well as in advanced subjects like Optimal Control etc. would be suitable for this research. The candidate may have to undergo some advanced courses in HBNI.

3.3 Modal Modeling and Identification of Flux Modes for AHWR (Contact person: Dr. B.B. Biswas)

Advanced Heavy Water Reactor (AHWR) is a third generation nuclear reactor being developed at BARC, targeting the utilization of Thorium for commercial power generation. The physical dimensions of AHWR are large compared to the neutron migration length in the core, due to which a serious situation called “flux tilt” may arise. A suitable space-time kinetics model of AHWR is necessary to be developed for analysis and control of such situations. Nodal and Modal modeling approaches are two promising candidates for developing such a mathematical model. In nodal modeling or multipoint kinetics approach, the reactor core is considered to be divided into a few number of coarse meshes whose mutual interactions are represented through coupling coefficients. In modal modeling approach, the space-time dependent flux distribution in the core is expressed as a weighted sum of a base set of precomputed spatial natural-mode functions (flux modes such as λ modes, π modes etc.) with time varying coefficients. In the former method, the challenging task is to devise a suitable nodalization scheme whereas in the latter, it is the computation of the set of flux modes suitable for representing any higher order flux harmonics which may arise in the core during reactor operation.

In the recent past, development of nodal models and derivation of suitable nodalization schemes have been carried out for AHWR and 540 MWe PHWR. However, development of a modal model and identification of the number and shapes of the basic flux modes for different core configurations of AHWR is still an unresolved problem. Having derived a modal model, number and shapes of flux modes may be arrived at by inspecting the steady state as well as transient accuracy of the model with different sets of flux modes. A number of different approaches to the development of modal models and identification of flux modes already appear in the literature. However, application of such techniques to AHWR would be an original contribution.

It will be another challenging and seldom attempted task to formulate the modal model in a linear state space domain. Once this is accomplished, the suitable set of flux modes may further be arrived at by investigation of linear system properties of the model such as stability, stabilizability and detectability, which will be a novel approach in identification of flux modes.

This research work would tentatively involve the following activities:

1.    Literature survey on modal modeling, computation of flux modes and other relevant

domains.

2.    Development of a modal model considering crucial variables such as one or more group

fluxes or power, and precursor, iodine and xenon concentrations {\it etc.}

3.    Computation of suitable set of flux modes by inspection of model accuracy.

4.     Linearization and state space representation of the modal model.

5.     Computation of suitable flux modes by investigation of linear system properties.

Pre-requisites: It is envisaged that any candidate with a thorough command over the undergraduate subjects would be capable of undertaking this research. However, the candidate may require to undergo certain advanced courses offered by HBNI.

 

Dr. C.P. Kaushik

4. Radioactive Waste Management

4.1 Separation of ruthenium from aqueous solutions (Contact person: Dr. C.P. Kaushik)

Separation of ruthenium from aqueous streams has been challenging in view of its variable oxidation states and ability to form stable nitrosyl complexes in nitric acid media. Ruthenium has got important medical as well as other industrial applications.

The present problem aims at exploratory investigations for separation /recovery of ruthenium from nitric acid solutions in presence of other constituents like Cr, Ni, Fe, Al, U, Cs, Sr and Pd. Different approaches based on separation science like distillation, solvent extraction, ion exchange, sorption etc will be studied and a suitable technique shall be evolved. The promising techniques shall be subjected for their performance evaluation for separation / recovery of ruthenium from synthetic nitric acid containing effluents having above said constituents. Various aspects like kinetics, mechanism of separation, optimum experimental conditions for maximum recovery shall also be part of the investigation.

4.2 Denitrification of aqueous industrial effluents (Contact person: Dr. C.P. Kaushik)

Nitric acid is a commonly used reagent in fertilizer, nuclear and metallurgical industries. Large volumes of aqueous solution containing nitrate ions are generated as waste in these industries. Nitrate is a wide spread contaminant of ground and surface water. It is a potential human health threat especially to infant causing the condition known as Methemoglobinema, also called ‘blue baby syndrome’. Nitrate is converted in the gut to nitrite which then combines with hemoglobin to form methemoglobin, thus decreasing ability of blood to carry oxygen. High nitrate levels in water may also led to reduce vitality and increased stillbirth, low birth weight. In view of above, industrial effluent are monitored for nitrate before discharging to environment to ensure that a regulatory limit of 44 ppm set by Central Pollution Control Board is met with respect to nitrate.

As the nitrate ion is very stable, conventional treatment methods such as precipitation, filtration, adsorption etc. are not effective for nitrate removal. The present problem aims at feasibility studies for removal of nitrate ions from industrial effluents. Processes like thermal, chemical, biological denitrification shall be explored to evolve a suitable methodology for removal of nitrate from industrial effluents.

4.3 Study of corrosion behaviour of Cr-Ni alloys in molten vitreous conditions (Contat person: Dr. C.P. Kaushik)

Cr-Ni alloys are one of the candidate materials for making melters, thermo-wells for immobilization of radioactive waste in vitreous matrices. Operating temperatures during preparation of glasses are in the range of 950-1050 oC. Estimation of usable life of melter / other components under prevailing conditions with respect to high temperature and reactive molten glass assume importance for designing and optimizing the use of melters under existing service conditions.

The present study shall cover detailed investigations of corrosion behaviour of different Cr-Ni alloys (inconel-600, inconel-690, inconel-693) with molten glass in the temperature range of 900-1050 oC for different time durations. Estimation of corrosion rate, mechanism of corrosion, surface alteration, and dependence on glass composition will also be the part of intended studies.

4.4 Development of modeling techniques to understand the performance of melters (Contact person: Dr. C.P. Kaushik)

Joule heated ceramic melters (JHCM) are used for vitrification of radioactive waste. The principle behind the operation of JHCM is the ability of molten glass to be an electrical conductor at high temperatures. An alternating electric current passing between electrodes immersed in the glass kept in a ceramic-lined furnace generates heat by the joule effect (Q = I2R). This dissipated resistive heat keeps the glass in the molten condition and processes the incoming waste and glass formers and vitrify the waste.

In a ceramic melter, glass is contained in a ceramic lined furnace. The glass contact refractory is designed with indigenously available Alumina-Zirconia-Silica (AZS) refractory with minimum possible thickness considering corrosion aspects and all other required features necessary for the melter. Bubble alumina as backup refractory is provided to reduce molten glass migration. Standard insulation materials like insulation brick, fiberboard and fiber wool were chosen and layer thickness and arrangement also are chosen carefully to optimise all the design parameters. Silicon carbide heaters are installed in Cr-Ni-Fe tubes (manufactured by Advanced Powder Metallurgy techniques) inside the melter in a leak tight manner to facilitate heating to increase the conductivity of the start-up glass so that it can start conducting and electrode power supply system can take over. The present problems aim at development of modeling techniques to understand the performance of melters. The work involves simulation of all the components of melter and development of modeling with respect to heat transfer fluid flow and mass transfer. The study assumes importance for future designing of melters and understanding the performance of melter.

4.5 Assessment of long term durability of vitrified waste product in near repository
conditions.
(Contact person: Dr. C.P. Kaushik)

High level radioactive liquid waste accounting for almost 99% of the total radioactivity generated in entire nuclear fuel cycle is immobilized in glassy matrix with ultimate objective of emplacing them in deep geological repositories to isolate radioactivity from human environment for extended periods of time. The long term performance of this vitrified waste product in deep geological environment (VWP) is controlled by number of processes and parameters like pH/Eh, composition of ground water, rock composition, temperature and presence of man made materials like clays, sand, backfill and concretes.

The commonly adopted methodology for assessment of durability of these VWP in these conditions include simulations of repository conditions in lab scale experiments in flow reactors and reactor vessels, where the conditioned products are made to react with water of varying composition under controlled conditions. Experimental observations obtained by these experiments like leach rate, thickness of leached layer, sequence of phase formation are extrapolated to longer time scale through application of geo-chemical computer codes like REACT,EQ3/6,KINDIS etc.

The proposed study shall include preparation of glasses of different compositions, their detailed characterization in terms of homogeneity, thermal conductivity, chemical composition etc, preparation of sample specimen with appropriate dimension and preparation of synthetic water representing repository conditions in terms of chemical, biological characteristics and conducting experiments for long duration in terms of thousand hours. Detailed characterization of leachate as well as leached layer will also be a part of investigation. Quantification of the leached layer, surface alteration, reaction rate energetic etc. shall also be covered as apart of investigations. Use of these experimentally obtained values in suitable geochemical code to predict the performance of VWP over thousands of years followed by validation of results using natural analog glasses.

Dr. K. Anantharaman / Shri S.K. Sinha, BARC

5.1 Heat Transfer and Pressure Drop Characteristics of Supercritical Fluids (Contact person: Dr P.K. Vijayan)

Supercritical reactor systems are almost fifty percent more efficient than the present light water reactors (LWRs). Besides supercritical fluids can be directly sent to the turbine eliminating the need for steam generators, separators and dryers. Further, supercritical reactors are considerably small in size, require considerably smaller pump rating and can be designed with vessel wall temperatures smaller than the LWRs that exist today. From the viewpoint of thermal hydraulic design, supercritical fluids are advantageous since the Critical Heat Flux (CHF) phenomenon that limits the reactor power is eliminated as it does not undergo phase change. Supercritical fluids, however, are reported to undergo heat transfer degradation near the pseudo critical point which is much milder in terms of the surface temperature rise compared to CHF. Although, supercritical reactor systems operate much above the pseudo critical point, heat transfer degradation could be important during transients and accidents.

All the reported heat transfer degradation cases are for vertical tubes. Even in this case, adequately validated heat transfer degradation models do not exist. Conventional correlations for heat transfer are not suitable for the supercritical region where the property changes are dramatic. Besides, the only reported work on rod bundle heat transfer with supercritical fluid did not observe heat transfer degradation. Also, there are not enough data on the pressure drop characteristics of supercritical fluids. In this context, it is proposed to experimentally study the heat transfer and pressure drop characteristics in tubes (vertical and horizontal) and rod bundles (horizontal and vertical). The results generated will be compared with existing correlations as well as predictions of CFD codes.

Facilities available: A supercritical carbon dioxide loop is already operational with provisions for measuring heat transfer in horizontal and vertical tubes. A supercritical water loop is under construction.

 

5.2 Steady State and Stability Characteristics of Supercritical Systems (Contact person: Dr P.K. Vijayan)

Supercritical reactor systems are being studied due to their economic advantages and simplicity. However, near the critical region, all fluids experience steep changes in fluid properties. Of particular interest to supercritical reactor (SCR) systems is the steep decrease in density in the near critical region. This decrease in density is comparable to that exist in present day Boiling Water Reactors (BWRs). As a result, supercritical reactors are susceptible to density wave oscillations. On the positive side, natural circulation becomes a viable option for coolant circulation in SCRs. However, both the forced and natural circulation type reactors need to avoid instability which can impose severe operational limits. Thus there is a need to develop theoretical formulations and computer codes to study instability and their experimental validation which is the proposed objective of this PhD project.

Facilities available: A supercritical natural circulation facility is operational with CO2 as the working fluid. A theoretical formulation based on 1-D approach is available.

5.3 Techniques to avoid thermal stratification in large pools with immersed heat exchangers (Contact person: Dr. P.K. Vijayan)

 Many of the advanced power reactor designs employ a passive decay heat removal system utilizing heat exchangers immersed in large water pools. The effectiveness of the pools as heat storage devices is somewhat degraded due to the thermal stratification phenomenon. Besides, it can also lead to unacceptable temperatures in the concrete boundary walls of the pool. Also, it can also lead to unacceptable steaming rates and pressurization if the water pool is located inside the containment. Therefore, incorporation of various techniques to avoid thermal stratification is necessary. These techniques will also significantly reduce the steam generation rate within the containment besides avoiding the limitation on concrete temperatures. It is proposed to study the influence of different types of baffles on the thermal stratification phenomenon. The study would involve both experimental and CFD simulations with the proposed baffle configurations.

Facilities available: Test facilities with immersed heat exchangers are available as well as CFD codes.

5.4 Finite Element, Modal Testing and Modal Analysis of Turbine Blade (Contact person: Shri A. Rama Rao)

This topic is concerned with the finite element analysis and modal testing of an industrial

turbine blade. The goal is to determine and verify the vibration characteristics of the blade using both experimental and analytical techniques. The finite element model of the blade will be built. The convergence properties of the FE model will be verified by mesh refinement and mass distribution methods. Next, a pre-test plan will performed before conducting a modal test in order to select the proper suspension points, driving point(s) and response points on the blade. Impact testing using hammer excitation and laser Doppler vibrometer (LDV) response measuring techniques will used to measure the vibration properties of the blade. Using a single point laser Doppler vibrometer, nodal diameters will be identified. Finally, a parametric study will be conducted on blade fixity, added mass on blade trailing and leading edge profiles.

5.5 Experimental and Analytical studies towards Development of Tubular Linear Electro-

magnetic Pump for Lead-Bismuth Eutectic Circulation (Contact person: Dr. D.N. Badodkar)

Brief outline of project Work: The project work involves evolving various schemes and methodologies followed in the design of electromagnetic pumps for liquid metal circulation, modeling of tubular electromagnetic pump, conceptual as well as detailed electrical design, experimental studies, analysis and evolution of the electromagnetic pump suitable for Lead-Bismuth eutectic circulation for specified applications.

Technology Advisor: B.S.V.G. Sharma, SO/H+ (Recognised faculty/ M.Tech guide of HBNI)

Guide: Dr. D. N. Badodkar, SO/H+ DRHR, BARC (Recognised faculty/ Ph. D. guide of HBNI)

5.6 Investigation on Premature Occurrence of Critical Heat Flux under Oscillatory Flow and Power Conditions (Contact Person: Dr. P.K. Vijayan)

Two-phase natural circulation loops have extensive applications in nuclear and process industries. One of the major concerns with natural circulation is the occurrence of the various types of flow instabilities, which can cause premature boiling crisis due to flow and power oscillations. The natural circulation flow characteristics are different from that of a forced circulation system. The flow in the former is dependent on the driving head caused by the density difference between hot and cold legs of the system. Many a times, the natural circulation flow is not fully developed and secondary flow may exist. So, under oscillatory conditions of such a system, the mechanisms of occurrence of the boiling crisis is more complicated and the flow oscillations can cause an early occurrence of the boiling crisis as compared to that of steady circulation even for the same geometric and operating conditions.

The effect of frequency and amplitude of flow and power oscillation on occurrence of premature CHF needs to be investigated. Substantial degradation in the CHF value during oscillatory flow conditions compared to the steady state CHF value has been reported. However, limited information on the effect of flow and power oscillation on CHF is available in the literature. The mechanism of the CHF degradation needs to be understood and mathematical modeling of this phenomenon is required to be developed. Experimental validation of the mathematical modeling should be carried out.

5.7 Physics of steam explosion (Contact person: Dr. A.K. Nayak)

 

Abstract: The phenomena of steam explosion is of relevance during severe accident in a LWR, when molten corium falls into subcooled water either inside calandria of a HWR or into the lower head of a LWR. Similar phenomena can occur when molten corium falls into subcooled water in the containment cavity of a LWR. There are numerous studies in the past in this field; however, the question still remains whether steam explosion can occur in a LWR. The study involves numerical simulation and experiments to understand the underlying cause of steam explosion and whether it can occur in nuclear reactor.

 

5.8 Numerical simulation of multi-dimensional multi-phase flow (Contact person: Dr. A.K. Nayak)

Abstract: Multi-dimensional multi-phase flow is of interest to the design and safety analysis of LWRs, especially in rod bundles. There are not enough studies in this regard. State-of-art codes consider homogeneous two-phase flow models. A few numerical models have been developed in recent past considering two-fluid multi field models. The study involves development of numerical model for multi-dimensional two-fluid model and application to rod bundle of a LWR.

5.9 Coupled 3-D neutronics thermal hydraulic stability analysis of a natural circulation multi channel type BWR (Contact person: Dr. A.K. Nayak and Dr. P.K. Vijayan)

 

Abstract: While there are several studies on thermal hydraulic stability of parallel channels of a natural circulation BWR, there are almost no studies on the 3-D neutronics coupled thermal hydraulic stability analysis of such reactors. Being natural circulation BWR, the core is relatively large size, housing several channels with different power and resistances. In view of this, the core is decoupled. With change in burn-up and operational transients, the reactor can experience complex thermal hydraulic stability behaviour than that understood for forced circulation BWRs. The study involves development of a numerical model considering coupling of 3-D neutronics and thermal hydraulic of a multi cannel natural circulation BWR and investigations of the stability of the reactor.

5.10 Study of gravity driven Steam Water Separation  (Contact person: Dr. A.M Vaidya)

In the boiler steam drums, two phase mixture from tail pipes enter and steam and water gets separated. The separation is by the effect of gravity. However, the fraction of liquid may escape to steam space (carry-over) and/or fraction of steam may escape to downcomer (carry-under). Both carry-over and carry-under are un-desirable. The experimental and computational investigation of entire steam drum is proposed to be carried out to understand the extent of carry- over and carry-under under different operating conditions.

5.11 Effect of non-condensable gas on condensation of steam with finned tube and various orientation of bare tube (Contact person: Dr. N.K.Maheshwari)

 

A key feature of the advanced nuclear reactors is the use of simple passive systems to respond to any postulated accidental condition. These systems utilise passive forces, such as gravity head, naturally induced density and pressure differences etc., to operate. One of these systems is the Passive Containment Cooling System (PCCS). Various types of PCCS has been proposed by researchers. One of the PCCS consists of Passive External Condensers (PECs). Each of these PECs consists of several tubes, internally cooled with natural circulation of water. In the event of an accident, large amount of steam enter the containment resulting in high pressures and temperatures that could threaten the structural integrity of the containment. Under such conditions steam condensation onto the PEC tube surfaces can reduce the pressure that in turn relieves the containment load. An important aspect of PCCS functioning is the degradation of the heat transfer coefficient on outside of the PEC tubes due to the presence of noncondensable gas. The work aims to investigate the effect of noncondensable gas on steam condensation. The effect of bare tube inclination on condensation and use of finned tubes will also be studied during the course of the project. Theoretical models will also be developed to study the effect of noncondensable gas on finned tube.

5. 12 Thermal hydraulic studies in a natural circulation of heavy liquid metal loop (Contact person: Dr. N.K. Maheshwari)

The High Temperature Reactor (HTR), being designed at BARC is to serve as a small power pack which has the potential for use in certain areas like, electricity generation in remote areas, supplying hot water, production of hydrogen and refinement of low grade coal and oil deposits to recover fossil fuel. Lead Bismuth Eutectic is selected as the coolant for HTR due to its excellent heat transfer capabilities good neutronic properties and inert to air and water. The project involves experimental studies on heat transfer and fluid flow in a high temperature heavy liquid metal natural circulation loop. Theoretical model will also be developed to study the natural circulation in liquid metal. Instability studies in liquid metal natural circulation will also be carried out. 3D CFD analysis of the complete loop is to be carried out and the results are to be validated against the experimental results. Various transient studies will be carried out experimentally as well as theoretically.

Reactor Physics Design Division

5.13      Simulations of physics systems relevant to needed developments for Advanced Reactor Applications (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

This is a research topic exploiting Monte Carlo methods ultimately to develop advanced research skills required for our own Monte Carlo code system compatible with ENDF/B files. The Ph.D. topic will focus on developing general Monte Carlo skills including variance reduction techniques for simulation of complex physics phenomena in general. However, finally, the candidate is expected to attempt to solve by Monte Carlo approach a deep penetration problem in a slab of single isotope such as Na-23 (used in fast reactors and in some ADSS concepts as coolant).

Analysis and benchmarking of Indian Shielding experiments performed in APSARA to international standard using ENDF and JENDL files will be part of this activity to get a practical perspective in advanced reactor shielding applications. Note that the candidate will be strongly associated with the problem of addressing the variance reduction that should be demonstrated for practically occurring probability distributions of physical interactions with actual evaluated nuclear data files such as ENDF/B-VII.0. A problem could be taking a deep penetration shielding problem of a single isotopic material such as liquid sodium (Na-23 isotope, 100% abundance) and using all relevant neutron interaction and photon-atom interaction data as a function of energy from 10**-5 to 20 MeV, angular distributions of elastic and inelastic processes for neutron and photon transmissions. Also published benchmark experiments should be analyzed with the software so developed. The aim is to evolve an ambitious and Indian equivalent (but still a small part of codes such as the MCNP) that can solve, as a first step, neutron transmission of a given flux of incident neutrons on one side upon a slab of few metres of Na-23. Variance reduction techniques, interfacing ENDF/B files will be challenges under this study.

5.14 Low energy (less than 4eV) scattering of neutrons by solids, liquids and molecules (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

 

One of the interesting areas is getting the characteristics, theoretically and experimentally, of scattering of atoms by atoms bound in molecules, liquids and solids. The candidate should be interested in physics studies of low energy (less than 4eV) coherent and incoherent scattering of neutrons by solids, liquids and molecules. These physics studies are useful in development of moderators and ultra-cold neutron source design related studies

This topic involves nuclear data physics, advanced reactor physics and engineering assessment for advanced reactor applications. The candidate will be trained by HBNI in related areas that include understanding available nuclear data and neutron physics in ENDF/B files, thermal scattering law physics and nuclear data for advanced reactors. The Ph. D candidate will also actively be involved in the creation, processing and applications of thermal scattering law nuclear data for systems such as Be in BeO, Be in Be metal, H in H2O, Hydrogen in Hydrogen metals (for ultra cold neutron applications), H in ZrH, D in D2), H in Polythene and several other bound systems with associated phonon emission spectra.

5.15 Numerical methods in neutron transport and multigroup and resonance shielding treatment for treatment of neutron physics transport for various advanced reactor applications (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

 

This Ph. D. topic relates to development of new numerical methods in neutron transport using detailed nuclear physics data that characterizes the physics of neutron nuclear interactions. This topic involves nuclear data physics and their treatment in solution of neutron transport equation using advanced computational physics tools in order to help advanced reactor physics and engineering assessment for advanced reactor applications. This includes nuclear data physics and reactor physics assessment for advanced reactor applications. The Ph. D. activity includes efforts on the part of the Ph. D student to understand basics of neutron physics, available international nuclear data and its physics in ENDF/B files for resonance data creation, formats, processing and condensation. Evolution of Indian updated reactor physics software to perform coupled neutron-gamma, gamma-neutron calculations in MATXS formalism is a challenge under this topic. Comparisons of MATXS format technology of multigroup treatment and advances over existing WIMSD treatment will be performed for a few cases.

5.16 Neutron Physics studies of experimental criticality benchmarks for thorium utilization; (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

  

Assessment and inter-comparison studies using JENDL, ENDF and other nuclear data files

Thorium utilization related experimental criticality benchmarks will be comprehensively compiled.

As part Ph. D course work and basic training, the candidate will also be trained in experimental techniques in Advanced Heavy Water Reactor Critical facility at BARC.

Advanced analysis of selected reactor physics benchmarks for thorium utilization and an assessment and inter-comparison studies using JENDL, ENDF and other nuclear data files will be performed by the Ph. D. candidate.

ICSBEP (http://icsbep.inl.gov) contains over 4200 high quality experimental benchmarks. The work of the ICSBEP is documented as an International Handbook of Evaluated Criticality Safety Benchmark Experiments. Currently, the handbook spans over 47,000 pages and contains 476 evaluations representing 4207 critical, near-critical, or subcritical configurations, 24 criticality alarm placement/shielding configurations with multiple dose points for each, and 155 configurations that have been categorized as fundamental physics measurements that are relevant to criticality safety applications. The handbook is intended for use by criticality safety analysts to perform necessary validations of their calculational techniques and is expected to be a valuable tool for decades to come. The Handbook is currently in use in 60 countries.

The Ph. D. student will have the opportunity to learn benchmarking of critical systems

Benchmarks published in literature but not yet included in the ICSBEP handbook will also be scanned and examined critically for their use in India’s advanced reactor applications. The Ph. D. student will be trained in the use of discrete ordinates and Monte Carlo methods. The candidate is expected to carry out a number of sensitivity studies using advanced software and perturbation theory based tools by discrete ordinates method and Monte Carlo simulations. The candidate is expected contribute to Indian creation of benchmarks as well.

 

 

5.17 Basic nuclear data physics studies using nuclear models and cross section measurements and analysis in Indian facilities. (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

 

Nuclear data physics involves physics measurements of particle- nuclear interaction data for advanced reactor applications. The Ph. D. candidate will work in a collaborative project under RPDD-NPD-RCD framework to measure data important of Indian reactor design applications. Considerable understanding of Quantum mechanics and nuclear physics with emphasis on neutron interactions will be part of course work. Special techniques like surrogate nuclear reaction techniques will be employed. Accelerator facilities such as Pelletron at BARC-TIFR and neutron sources such as in BARC, Pune, IPR and other places will be employed. Nuclear physics model codes such as TALYS and EMPIRE and other locally developed codes will be employed to predict nuclear data and compared with experimental data. The candidate will also be expected to make EXFOR entries based upon Indian experiments into the IAEA database system.

5.18 Nuclear data physics studies of Photo-fission experiments, delayed neutron physics and assaying of fissile materials: (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

 

This physics research study involves collaboration with several groups in BARC. Several fundamental measurements to newly generate nuclear physics data of photon induced fissions in various actinide substances using the Electron Beam Centre 10MeV accelerator at Kharghar will be performed. The research tasks include working with various types of neutron detectors and their development in Electronics Division in collaboration with RPDD, understanding photo-fission process from fundamentals, simulation of electron and gamma interactions with atoms and nuclei.

The characterization of delayed neutron groups arising from gamma induced nuclear fission in actinides and digesting the existing physics databases to improve quality of physics data is part of the activity.

5.19 Analysis of resonance cross section measurements and Neutron Time of flight experiments (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

 

This is an interesting topic in neutron physics. The candidate will be involved in the physics analysis of n_TOF experiments to measure resonance cross section data of selected elements/isotopes. This involves a thorough understanding of physics of neutron interactions with nuclei. Understanding various resonance formalisms such as Reich Moore, Multilevel treatment etc. Understanding the various corrections (thick target, Doppler effect, resolution functions etc. ) during analysis of raw transmission data. The in-house fabrication of Fermi neutron chopper and time-of-flight related data collection and electronics is part of the activity. Participation in foreign collaborations such as in Korea and CERN may be a possibility depending upon the progress and success of the selected candidate. Understanding the resolution of the n_TOF apparatus and role of detectors is an essential part of this activity

5.20 Radio-toxicity predictions for AHWR, CHTR, PHWR, PWRs etc.  (Contact person : Dr. K. Anantharaman and Shri S.K. Sinha)

 

Develop a comprehensive Indian approach to assess the decay heat predictions for AHWR, CHTR etc., for both the Pu_U and the thorium fuel cycle. Update ORIGIN code and its database. Collaborate on identification of nuclides for total Absorption Gamma Spectroscopy (TAGS) experiments. Thorium fuel cycle related nuclear data and its adequacy will be addressed.

Shri K.C. Mittal / Dr. L.M. Gantayet, BARC

6. Beam Technology Development at BARC (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

Introduction

Beam Technology Development Group (BTDG) at BARC has been developing technologies of high intensity, electron, laser and plasma sources. Laser Division in BTDG is concentrating on research and development of high intensity laser, plasma and electron beam. Accelerator and Pulse Power Division of BTDG is concentrating on research and development on electron accelerators, pulse power, Superconducting RF cavities and high intensity ion sources. ADS Target Development Section is studying target design and development for 1 GeV proton beam for ADS applications. A number of gaps exists in the understanding of these areas of work. A few topics for conducting research in the above areas are listed in the following sections

6.1 Accelerator Science and Technology

6.1.1 High Power Industrial Accelerator Development and Utilisation (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Accelerators are now finding increasing applications in Industrial, Medical and Security fields. This involves development of accelerator technology with demanding requirements on beam parameters. Industrial applications are now being pursued in India and this area is expanding. Gamma Ray sources have been in use for medical sterilization and food preservation etc. But now Electron Accelerators with beam parameters; 300 keV to 10 MeV, 1mA to 150 mA, 1 kW to 500 kW are in demand for food irradiation , medical sterilization, cross linking of polythene cables and sheets, vulcanization of rubber, pollution control etc. These are relatively new areas of accelerator utilization. However, process development in all these area is not complete. Therefore there is a greater need to understand the electron beam interaction with matter vis a vis radiation processing of materials.

Four Electron Accelerators with beam parameters of 500 keV, 10 kW; 3 Mev, 30 kW; 10 MeV, 10 kW and 9 MeV, 1 kW have been operational or under commissioning at BRIT, EBC and ECIL.

 

Suggested Topics for Ph.D are listed below:

 

6.1.1.1 Electron Radiation Processing and cross linking studies with polythene and otherpolymers using electron accelerators (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Electron Accelerators with beam parameters: 300 keV to 10 MeV, 1mA to 150 mA, 1 kW to 30 kW are now available for industrial applications at Electron Beam Center, BARC. Cross linking of polythene cables and sheets by electron irradiation improves electrical insulation and mechanical properties of the cables and sheets. Determination of optimized radiation levels theoretically and experimentally vis a vis electron beam energy and power for cross linking of polymers will be the scope of the thesis.

6.1.1.2 Determination of optimized radiation levels vis a vis electron beam energy and power for cross linking of polymers  (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

6.1.1.3 Process development for pollution control in thermal power stations with electron

accelerators: (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Coal based thermal power stations produce flue gases like SOx and NOx which pollute the atmosphere. A number of ways have been in existence to reduce pollutants in the atmosphere. Electron Beam accelerators have shown promise to reduce pollution levels. When high energy electron beam (~ 1 MeV energy) interacts with SOx and NOx of flue gases in the presence of water vapors and ammonia, fertilizers like ammonium nitrates and sulphates are produced. Work will involve experimental studies of reduction of flue gases using 3 MeV electron accelerator at EBC.

6.1.1.4 Basic studies on high energy electron beam interactions on NOx and SOx compounds

(simulation and experimental) (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Coal based thermal power stations produce flue gases like SOx and NOx which pollute the atmosphere. A number of ways have been in existence to reduce pollutants in the atmosphere. Electron Beam accelerators have shown promise to reduce pollution levels. When high energy electron beam (~ 1 MeV energy) interacts with SOx and NOx of flue gases in the presence of water vapors and ammonia, fertilizers like ammonium nitrates and sulphates are produced. Basic studies on interaction of high energy electron beam with flue gases using analytical and computational methods will be in the scope of this project. Work will involve experimental studies of reduction of flue gases using 3 MeV electron accelerator at EBC.

6.1.1.5 Optimised parameters determination of Electron beam processing of rubber compounds (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Electron Accelerators with beam parameters: 300 keV to 10 MeV, 1mA to 150 mA, 1 kW to 30 kW are now available for industrial applications at Electron Beam Center, BARC. Vulcanization of rubber using electron beam is a process that does not require any chemicals. This process improves the quality of the rubber for various application in industry like tyres. Theoretical and experimental studies are necessary to determine the process parameters. Accelerator facilities at Electron Beam center will be available for these studies.

6.1.1.6   High Energy beam transport in air and in gases at pressures higher than atmospheric

pressure. (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Electron Accelerators with beam parameters: 300 keV to 10 MeV, 1mA to 150 mA, 1 kW to 30 kW are now available for industrial applications at Electron Beam Center, BARC. Electron Beam transport in vacuum has been extensively studied in literature.

For industrial applications, high energy beam is extracted into air for radiation processing applications. High intensity beam transport in air at atmospheric pressure and higher is necessary to know radiation processing effects. This project will involve studying computationally and analytically beam transmission efficiency as a function of distance and beam energy. Experimental verification on the 3 accelerators at EBC will also be possible

6.1.1.7 Electron beam interactions with grain and food products (theoretical/ experimental)

(Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Electron Accelerators with beam parameters: 300 keV to 10 MeV, 1mA to 150 mA, 1 kW to 30 kW are now available for industrial applications at Electron Beam Center, BARC. These beams have been used for disinfestations of grains and preservation of food products. It is very necessary to know radiation levels for various processes. Work will involve determination of required radiation dose levels for various processes and experimental verification on the accelerator facilities available at EBC.

6.1.1.8 Studies and development of high intensity electron guns using thermionic emission (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Electron Accelerators with beam parameters: 300 keV to 10 MeV, 1mA to 150 mA, 1 kW to 30 kW are now available for industrial applications at Electron Beam Center, BARC. These accelerator require an electron beam dc or pulsed in the range of 3 keV to ~80 keV to be injected into DC or RF accelerators. The quality of the accelerated beam depends on the beam intensity and divergence of the injected current from the electron gun. Design and development of suitable electron gun will be in the scope of this project. Studies on field emission from carbon nano tubes will also be in the scope of this project.

6.1.1.9 Studies and development of high intensity electron beam with field emission from

diamond like carbon cathodes for electron accelerators (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

6.1.1.10 High intensity X ray production studies with Accelerator electron beams and

focusing. (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

These topics can be taken up by polymer chemists, physicists, electrical/ electronics engineers, agriculture physicists etc. The topics are mainly multi disciplinary.

 

6.1.2 Pulse Power Technology and Utilisation (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

APPD has a very strong programme in the development and utilization of 1 to 100 GW, 10 to 100 ns single pulse systems for applications in High Power Microwave (HPM)and Flash X ray (FXR) generations. KALI 75, KALI 200, KALI 1000 and KALI 5000 systems have been developed in this series. Induction Linac with repetitive pulses is also in development.

The following topics for Ph.D can be taken up by prospective students :

6.1.2.1 Explosive Field Emission simulations for Gigawatt to Terrawatt pulse electron beams (Physics)

6.1.2.2 Analysis of pulse power Systems (Gigawatt to Terrawatt) for low rise and fall time pulse generations (Elctronics)

6.1.2.3 Design and analysis for development of Repetitive pulse power systems (Electrical/ Electronics)

6.1.2.4 Alternate concepts in design of compact pulse power systems at Gigawatt power level (Electrical/Electronics)

6.1.2.5 Analysis of Experimental results from HPM and Flash X ray Generations in large laboratories (Physics/ Computer)

6.1.2.6 Design and simulations for High intensity HPM (high Power Microwave > 100 MW) generation in Vircator, Backward Wave Oscillator, traveling Wave Tube devices (Physics)

6.1.2.7 Simulations of Intense Flash X ray generation devices in gigawatt to Terrawatt range (Physics)

6.1.2.8 Development of Single pulse microwave diagnostics for HPM devices (Electronics/ Physics)

6.1.2.9 High Intensity Electron Beam (> few giga watts) Transport in air, gases and plasmas (Physics)

 

6.1.3 SCRF and ADS Technology: (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Super Conducting RF cavity development and high intensity proton ECR ion sources fall in this category. Elliptical niobium cavity operating at 700 MHz and 1050 MHz for 5 to 15 MV/m accelerating gradients are being studied. An ECR Ion Source at 50 keV, 50 mA proton beam as injector for 20 MeV proton Linac is under development.

The following topics for Ph.D. can be taken up by prospective students

6.1.3.1  Simulations using CST Microwave Studio and other codes for designing cavities at

specified beam parameters.

6.1.3.2 Higher Order Mode Couplers design at specific beam parameters

6.1.3.3 Beam dynamics in elliptical cavities

6.1.3.4 RF Sources development and integration

6.1.3.5 Physics and Technology of ECR Ion source

 

6.2 Laser & Plasma Technology Division, Beam Technology Development Group (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

Laser & Plasma Technology Division of Beam Technology Development Group executes a host of R & D intensive programmes on high intensity, lasers, plasmas and electron beams. The following topics may be considered as focused areas of activity in HBNI Ph.D. Scheme. Each of these areas is connected to a theme program of BARC.

6.2.1 Laser matter interaction:  (Contact person: Dr. Sucharita Sinha)

 

The topic Laser-matter interaction includes research and development related to pulsed laser deposition, laser etching of materials, laser assisted surface cleaning, laser glazing etc where nano to pico second lasers will be used develop applications of lasers to nuclear applications. The post laser treated surface will be studied by surface analysis techniques making use of sophisticated diagnostic tools/techniques e.g., SEM, advanced optical microscopy, AFM, surface profilometer, LIBS etc to study the interaction processes and also to gain an in-depth knowledge of the physical processes operative herein. In addition, the work will also be directed towards applying these laser surface techniques in the areas of specific interest to DAE.  These  include short pulse laser based surface etching of thoria pellets, cleaning of radioactive metallic/dielectric surfaces containing fixed/ loose contamination, removal of loose contamination without modifying the surface properties, modifying the surface properties without altering the properties of the bulk material, e.g, laser assisted surface hardening etc.  

 

6.2.2 Spectroscopy of actinides and isotope separation (Contact person: Dr. B.M. Suri, Dr. Vas Dev and Dr. G.K. Bhowmick)

 

Laser Spectroscopy of Lanthanides and Actinides is of great interest both to basic scientists and technologists. These spectra are normally classified as complex spectra. These studies got a fillip in early eighties with the development of tunable lasers, efficient photon and ion detectors as well as novel atomic, molecular and ion sources. These studies have relevance both in vapor phase as well as condensed phase. Basic scientists had been particularly interested in advanced studies which will better explain astrophysical spectra, as test cases for parity violation, observing and interpreting trends in nuclear and atomic structure and validation of latest structure models. Plenty of work has been done in these areas in last two to three decades but it is still tip of an iceberg. In applied areas, maximum interest so far has been on solid state spectroscopy of rare earth doped glasses for laser materials and developing efficient commercial lamps of various colors and hues. Ultra-trace analysis of many of these radiotoxic isotopes is required for environmental monitoring (these techniques supplementing or better than conventional techniques). Many of the lanthanide and actinide isotopes are present in waste streams and need to be monitored with sensitivity, selectivity or in online mode. All these above mentioned problems can throw challenges. Special mention has to be made on generation of ultra-pure radioactive ion beams which are expected to usher in renaissance of nuclear physics. As can be seen, laser spectroscopy offers enough challenges and opportunities to scientists for few decades to come.

 

6.2.3 High Power narrowband lasers for ion source & isotope separation (Contact person: Dr. Sunita Singh and Dr. K. Dasgupta)

 

The Objective of the program would consist of design and development of high pulse repetition frequency (PRF), high average power, efficient laser drivers for generating narrow-band, precisely tunable laser output at visible and near infra-red wavelengths. The high repetition rate, narrow-band, tunable lasers are extremely useful tool for the RIS process studies, trace analysis and detection, study of fundamental properties of laser ion source etc. The need for high PRF in these activities arises because it allows higher process throughputs and higher sensitivity detection with smaller quantity of sample. The narrowband part helps in addressing a particular species with isotopic / elemental selectivity in presence of other elements / ions. The heart of such system consists of high repetition rate pump laser system that pumps efficiently a tunable laser medium to produce tunable, narrowband laser output at required wavelength(s). In case of pump laser system, apart from well established CVL system, the solid state laser system based on Neodymium or Ytterbium doped YAG crystal in the form of a rod is used for producing high average power output at multi kHz PRF. Generally, these lasers produce outputs at wavelengths close to one micron and second harmonic generation and frequency mixing techniques are used to convert them to visible and UV regions for pumping various tunable lasing media. The basic design philosophy of these lasers is to pump gain media by continuous wave high power diode laser stacks and produce pulsed outputs through Q switching. On the other hand, liquid dye lasers are most commonly used tunable laser systems for above applications. But these dye lasers require circulation of large quantity of hazardous liquid and thus require stringent safety procedures. Tunable laser based on Ti:Saphhire, Cr:Forsterite and optical parametric oscillator (OPO) offer large tuning ranges and avoids major limitations of dye lasers like requirement of liquid circulation, material degradation and flow induced fluctuations. The main design challenge in the high PRF, high power operation of solid state laser lies in fast removal of excess heat that are produced in the excitation process in order to eliminate distortion of laser beam and damage of gain medium. In case of Nd-YAG laser, new, innovative optical design is necessary for efficient coupling of highly divergent diode laser output to the YAG rod and overall optimization of the resonator cavity to produce high average power output with good beam quality. In the case of liquid dye laser, working at high repetition rate is much easier. But for solid state medium like OPO, Ti:Saphire and Cr:Forsterite efficient handling of heat dissipation inside the gain medium is a major challenge in high repetition rate operation. This requires study of thermo-optic properties of these materials at low temperature. In case of OPO, new design is required for pumping OPO in order to reduce its high threshold. New resonator design is necessary to produce precisely tunable, narrowband OPO output. Also in case of dye, requirement is there to design and characterize efficient new dye molecule and study its interaction with different solvent medium.

 

6.2.4 Plasma assisted surface modification in low pressure, low temperature plasmas (Contact person: Dr. A.K. Das and Dr. D.S. Patil)

 

Low pressure plasmas are finding a lot of applications in the field of materials processing. These plasmas are unique in terms of generation of chemically reactive species at low temperature and this is due to the non equilibrium nature of the plasma state. Due to high internal energy of low pressure plasma (because of the presence of the charged particles), processes which are thermodynamically allowed but kinetically hindered in a conventional process, proceed with a high rate under plasma conditions. These plasmas are widely used for various industrial processes including thin film deposition by Chemical Vapour Deposition (CVD), Physical Vapour Deposition (PVD) including Magnetron Sputtering and semiconductor manufacturing. Because of the inherent advantages we have a focused program in low pressure plasma surface enginnering in the following areas:

1)     Microwave plasma assisted chemical vapour deposition of oriented diamond films for nuclear detector applications.

2)     Microwave Electron Cyclotron Resonance (ECR) plasma assisted chemical vapor deposition of Diamond like Carbon (DLC) containing nanocomposite films and their Characterization.

3)     Microwave Electron Cyclotron Resonance (ECR) plasma assisted metal organic chemical vapour deposition (MOCVD) and characterization of oxides like Y2O3 and Yttria stabilized Zirconia (YSZ) and other oxides for specialized applications.

4)     Plasma assisted chemical vapour deposition of carbon nanotubes for specialized applications and their characterization.

5)     Magnetron sputtering for deposition of hard coatings and characterization.

 

6.2.5  Diagnostics of Thermal and Non thermal Plasmas (Contact person: Dr. A.K. Das )

 

Low temperature plasmas provide new and innovative techniques for materials processing. Plasma spray coating of metals and ceramics, Low pressure plasma surface modification through PVD and PECVD techniques, Plasma assisted nano structure synthesis, Plasma cutting, melting, welding and high temperature plasma synthesis are few of the applications of interest to the Department of Atomic Energy. Apart from development of plasma sources, diagnostics of these plasmas in relation to each of the above applications is an important thrust area. In this connection, Electric and magnetic probes, enthalpy probes, electron & ion energy analysers, High speed imaging, Laser based particle diagnostics, Laser induced fluorescence and emission/absorption spectroscopy are few of the techniques that are being developed and implemented in our laboratories. The student will get an opportunity to work on in situ process diagnostics of these plasmas.

Resource Person : Dr. A. K. Das

 

6.2.6 Electron Beam Vapor deposition and development of multilayer coatings (Contact person: Dr. A.K. Das and Smt. N. Maiti)

 

Electron beam evaporation employs electron beams to directly heat the evaporant through impinging electrons. This provides direct control on the evaporation process as well as simplifies the temperature constraints on the crucible containing the evaporant. A controlled vapour stream from materials commonly difficult to evaporate is used to develop thin film coatings. In addition to the control of the evaporation rate at low fluxes this method minimizes contamination of the vapour stream for sensitive application areas such as surface science or thin-film doping. For example, the coating compositions can be varied continuously, as in so-called Functional Gradient Coatings (FGC). Also, coatings comprised of

alternating layers of different compositions can be made. These multilayered coatings can be applied on top of the FGC. The EB-PVD process offers many desirable characteristics such as relatively high deposition rates (up to 150 urn/minute with an evaporation rate of app. 10-15 Kg/hour), dense coatings, controlled composition control and microstructure, low contamination, and high thermal efficiency. Coatings produced by the EB-PVD process usually have a good surface finish and a uniform microstructure. The microstructure and composition of the coating can be easily altered by manipulating the process parameters and ingot compositions. Thus, multilayered ceramic/metallic coatings can be readily formed and various metallic and ceramic coatings (oxides, carbides, and nitrides) can be deposited at relatively low temperatures. Even elements with low vapor pressure such as molybdenum, tungsten, and carbon are readily evaporated by this process. L & PT Division has a 10 Kw, 10KV, 270 0 bent beam type evaporation system being used for development of novel coatings. The program would look at understanding the coating process, optimization and development of optical coatings.

 

 

6.2.7 Computational dynamic Simulation of Plasma jets, low pressure plasma materials processing systems and nano material formation. (Contact person: Shri K.C. Mittal and Dr. L.M. Gantayet)

 

Computer simulation of plasma and electron beam assisted processes are absolutely necessary to understand the process mechanisms, interplay of various complex physical phenomena affecting the process system, process optimisation and assist device design. The various computer simulation problems being handled at L & PT Division include :

a.     Charged particle generation and dynamics in low pressure plasma CVD system

b.     Flow, heat transfer and chemical reaction in high pressure plasma jets and reactors

c.     Homogeneous and heterogeneous nucleation and growth of nanostructures in plasma nano

generators

d.     Computer simulation of electromagnetic and thermal fields in RF plasma systems

e.     Process simulation in Electron beam evaporation and coating

f.      Computer simulation of plasma spray as well as wire arc spray process.

g.     Modeling of radiation emanating from a plasma column

Each of these computer simulation is supplemented by a plasma diagnostics technique for validation of data. 

  

6. 3 ADS Target Development Section , Beam Technology Development Group (Contact person: Dr. LM Gantayet, Dr. AK Das, Dr P. Satyamurthy))

 

1.     Target design and development for 1 MW proton beam is one of the main activities in this section. Topics related to proton energy deposition in spallation targets and neutron production can be taken up by Ph.D students

2.     Liquid metal MHD related problems in the liquid metal coolant circuit in the Test Blanket Module of the ITER Project has many challenges to be solved. Both experimental and theoretical modeling are carried out in the ADS Target Development Section.

Contact Persons:

Dr. LM Gantayet, Director, BTDG, BARC, gantayet@barc.gov.in

Dr. AK Das, Head, Laser and Plasma Technology Division, BTDG, BARC; akdas@barc.gov.in, 022 25593823 (O)

Dr P. Satyamurthy, Head, ADS Target Development Section, BTDG, BARC; lmmhd@barc.gov.in, 022 25593822 (O)

 

Conclusions:

Beam Technology Group at BARC has been carrying out research and development in front line areas of science and technology. High power laser, electron and plasma beams have found a large number of industrial, research and technological applications. A large number of research topics are open for taking up by prospective students under Ph.D programme of HBNI.

Dr. H.S. Kushwaha, BARC

7.1 Wavelet Analysis in Structural Health Monitoring and Damage Detection (Contact person: Dr. H.S. Kushwaha)

Wavelet analysis has been increasingly applied to a great variety of engineering problems that are connected to the detection of structural damage and structural health monitoring. Identification of structural damage based on vibration data that is required on a mechanical system. The considered systems range from rotating machinery to large civil engineering structures. Accordingly, the specific problems and respective algorithms are manifold. While some approaches are focused on structural health monitoring analyzing data acquired under service conditions, other methods were developed for specific dynamic tests which are performed, for example, in the context of regular inspection.

The wavelets are usually oscillating, rapidly decaying functions. Generally, three types of wavelet transformation can be used.

                  Continuous wavelet transformation;

                  Discrete wavelet transformation; and

                  Discrete wavelet packet transformation.

Some of the most often applied wavelets are the Haar wavelet and the Morlet wavelet. The multi-resolution analysis is the fundamental approach of discrete wavelet transformation, orthogonal and bi-orthogonal discrete wavelet analysis is recommended in flaw analysis compared to the discrete wavelet transformation, the wavelet packet algorithm decomposes the approximation as well as the details. Similar to the discrete wavelet transformation approach, a finite quadrature mirror filter and its corresponding high pass filter can be used. While some approaches are focused on structural health monitoring algorithms, data acquired under service condition other methods were developed for specific dynamic tests, which are performed in the context of regular inspection.

 

7.2 Extended Finite Element Method in Material Modeling (Contact person: Dr. H.S. Kushwaha)

 

The Extended Finite Element Method (XFEM) is a versatile tool for the analysis of problems characterized by discontinuity, singularities, localized deformations and complex geometries. These methods can dramatically simplify the solution of many problems in material modeling such as:

                  The propagation of cracks

                  The evolution of dislocations

                  The modeling of grain boundary

                  The evolution of phase boundary

he advantage of these methods is that the finite element mesh can be completely independent of the morphology of these entities.

The major advantage of these methods for problems in material science is the simplification of the modeling of discontinuous phenomena. In conventional finite element methods, the mesh has to be constructed so that element edges/faces coincide with the crack surface and nodes must be placed on each side of the crack to allow material separation along the crack surface. The construction of such meshes become quite difficult, especially in 3-D problems, because the mesh also has to account for other features of the model, such as grain boundaries or inclusions.

In XFEM, the introduction of a discontinuous displacement field along the crack surface is accomplished by simply introducing additional basis functions to the approximation. When XFEM is combined with level sets, the entire representation of the feature, such as the geometry and the displacement field of crack, can be constructed in terms of nodal values at the nodes of the original mesh. These advantages are particularly important when the geometry evolves, as in a growing crack or moving phase boundaries. XFEM was developed for discontinuities, such as cracks, and used local enrichments. XFEM can be used with both structured and unstructured meshes. Structured meshes are used when properties of a unit cell of the material is important. Unstructured meshes, on the other hand, tend to be widely used for analysis of engineering structures and components since it is often desirable to conform the mesh to the external boundaries of the components.

The foundation of these methods in the partition of unity concept for enriching finite elements or mesh-free approximations. The method employ standard finite element (FEM) or mesh-free shape function and at the singularities enrichment functions are used. It should be pointed out that the shape functions for the standard approximation and the enrichment need not be the same functions. Problem related to material sciences, such as cracks in structures, cohesive crack, dislocations, grain boundaries can be treated very well with XFEM

.

7.3 Seismic Fragility Analysis of Nuclear Power Plant Structures (Contact person: Dr. H.S. Kushwaha)

Basic parameters for seismic design of structures and equipment intrinsically include various uncertainties. In particular, the randomness of seismic events does not allow the analysis to estimate reasonable structural seismic response by a deterministic method. The seismic probabilistic risk assessment (SPRA) is a tool to evaluate the actual safety considering the variability and the regulatory requirement for Nuclear Power Plants under construction as well as in operation. In the course of SPRA, seismic fragility analysis is the most significant and essential phase especially for structural or mechanical engineers.

A practical method for evaluating seismic fragility analysis shall be developed. It must be considered site-dependent response spectra. The response spectrum characteristic of earthquake motions shall be considered in evaluating seismic analysis of power plants components and system. This is highly important for the purpose of seismic PSA.

7.4 Low Cycle Multiaxial Fatigue Failure Under out-of Phase Loading (Contact person: Dr. H.S. Kushwaha)

The Engineering components in service are frequently subjected to the multiaxial cyclic loading, which can result in failure due to the fatigue damage. In general, the multiaxial fatigue life can be predicted by Von Mises equivalent stress or strain criterion. However, under out-of-phase or non-proportional loading, the principal areas of stress and strain rotate during cyclic loading, causing additional cyclic hardening or the material, which results in more fatigue damage. Some multiaxial fatigue models have been proposed for the prediction of multiaxial fatigue life. At present critical plane approach is widely used for the multiaxial fatigue life prediction, but it is required to determine the maximum damage plane and the stress or strain on the plane. This approach has been widely accepted to predict the multiaxial fatigue life. However, some damage parameters in these approaches usually include the weight constants that tend to increase as fatigue life increases. Sometimes it may be difficult to correlate the data for a wide variety of materials.

Hysteris loops under non-proportional loading showed that the stress and strain cannot reach their maximum value at the same time. The characteristics of cyclic plasticity have a lot of differences between proportional and non-proportional loadings. The dispersal degree of fatigue cracks under proportional loading is smaller than that of non-proportional loading. Critical plane approaches are based on the search of a material plane where a combination of stress quantities attains its maximum. Another approach considers measures associated with history of the stress tensor itself, instead of its manifestation upon each material plane. However, the major criticism upon this model was related to the non-uniqueness of the measure of the shear stress amplitude for some classes of stress paths. However, the fatigue life predicted by current approaches under multiaxial loading need to be reviewed and a better model may be developed to give realistic fatigue life.

7.5 Performance Based Seismic Design of Nuclear Power Plants (Contact person: Dr. H.S. Kushwaha)

From last two decades, there is a clear trend towards “performance-based” seismic design. It can be thought of as an explicit design for multiple limit state or performance levels. Analysing structures for various levels of earthquake intensity and checking some local and/or global criteria for each level has been a popular academic exercise for the last couple of decades, but the crucial development that occurred relatively recently was the recognition of the necessity for such procedures by a number of practicing engineers influential in code drafting. It was realized that while structures built in industrialized countries aware of the seismic risk are, in general, adequately safe, the cost of damage built in these structures by earthquakes as well as the indirect cost resulting from business interruption, need for relocation, etc. can be difficult to tolerate. This points to the need to address the problem of designing a structure for multiple performance levels (limit state) i.e. performance based design. Furthermore, the need to explicitly include displacement (or rift) as a seismic design parameter, rather than as a final verification of a structure already designed for a certain force level is increasingly being recognized.

The selection of the type of analysis to be used within the framework of a PBD procedure is also a topical issue, and inelastic analysis is gaining popularity during the last few years, a reason for this being that appropriate analytical tools are now available for performing both types of inelastic analysis , i.e. (“pushover”) and dynamic (time-history). Proposed design methods using inelastic analysis mainly involved dynamic time history analysis of “equivalent” single-degree-of-freedom (SDOF) systems and pushover or limit analysis of the entire structure, an idea originally suggested by Saiidi and Sozen (1981) and subsequently integrated into design methods for regular buildings, such as the N2 method. The idea of using inelastic time-history analysis for design purposes was also explored, but the suggested methods were of an interactive nature, i.e. a preliminary design was improved by successive time-history analysis that identified the weaknesses in that design. This is not necessarily a major handicap but, for practical design purposes, a procedure to judiciously obtain the initial design of the structure is clearly needed.

 

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