DARE TO DREAM:THE STORY OF THE METALLURGY AND

MATERIALS PROGRAMME

In December 1973, Dr. G. Venkataraman came on transfer from Bhabha Atomic ResearchCentre(BARC) to the then Reactor Research Centre (RRC), to initiate research in Materials Science. TheMaterials Science Laboratory formally came into being early 1974 with only two members – with theother member on deputation to Atomic Energy Research Establishment, UK. Soon however other memberscame on transfer from BARC and Tata Institute of Fundamental Research (TIFR) to join the laboratory.In June 1974, I landed in Kalpakkam with four of my colleagues from BARC, and within two weeks, Dr.Placid Rodriguez came with three of his colleagues to take charge of the Metallurgy research. Themandate was to plan and build a metallurgy R&D programme in support of fast reactor technology,including the post-irradiation examination facility. The facilities had to be built from scratch; only sixcreep testing machines (jocularly referred to as the “dowry”) had been transferred from BARC to RRC.The then Project Director, Shri N. Sreenivasan provided all support and guidance for these two nascentactivities. He also made his expectations very clear; he would accept nothing but the best – be worldleader in your chosen area of expertise. Thus began the saga of what we see to day as the Metallurgy andMaterials Programme.

Right from its inception, the Metallurgy Programme was conceived with a holistic and far sightedapproach: it would be developed to meet all the metallurgical R&D needs identified or anticipated forfuture. I was entrusted the challenging task of planning, design and operation of the hot cell facilities,and also developing and validating testing facilities for their eventual deployment in the hot cells, whichhas now matured into a premier facility. A comprehensive mechanical metallurgy laboratory has beensystematically built up over the years, with extensive creep and low cycle fatigue, fracture mechanicstesting, and laboratory scale melting and fabrication facilities. These were meant to cater to the needs ofnot only our Centre, but the DAE family as whole. All relevant areas, such as corrosion metallurgy forboth water and sodium environments under the guidance of Shri J. B. Gnanamoorthy, and a comprehensivephysical metallurgy facility for structure property correlation and basic researches in phase transformation,were planned right from the inception. Thermodynamics and kinetic studies were also added a few yearslater under the leadership of Dr. O. M. Sreedharan. Planning and implementation of the Materials Sciences

TECHNICAL ARTICLESAnalysis of Grid PlateTowards Remaining LifeAssessment of FastBreeder Test Reactor

Detection and Evaluation ofSensitisation andIntergranular Corrosion inAustenitic Stainless Steelsby Eddy Current TestingMethod

Prediction of ChlorideRedistribution during LongTerm Service Life ofConcrete Structure of PFBR

Development of Cross WireType Leak Detector

Forum for Young Officers

Structural Integrity of CoreCatcher under CoreDisruptive Accident Loading

Modelling theElectrorefining Process

Conference Highlights

Recent Advances inInformation Technology -READIT-2005

Medimeet 2005 andParamedics Meet

5th Quality Circle AwarenessDay-2005

TWENTY YEARS OF FBTROPERATION

Awards & Honours

ISSN 0972-5741 Volume 66 October 2005

INDIRA GANDHI CENTRE FOR ATOMIC RESEARCHhttp://www.igcar.ernet.in/lis/nl66/igc66.pdf

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motivate and nurture their young talent,which is considered as an unique and novelexercise in DAE units. I consider thathuman resources with comprehensiveR&D facilities are the keys to deliveringmature fast reactor technology to thecountry, and indeed for any meaningfulscience and technology programme. I havewritten a precise but comprehensive articlein International Union of MaterialsResearch Society’s Newsletter on R&DProgrammes of the Materials Programmesof the Centre. This would appear inNovember 2005 issue of IUMRSNewsletter (hardcopy and websitesimultaneously). Thus, I would not repeatthese details in my current article.

Success is inevitable with such acombination of a dedicated group of R&Dresearchers, sensitive about their mandate,proud of their achievements, and alwaysaspiring for more, an enlightenedmanagement, and the symbioticinteractions. And given the ever-wideningspiral of greater success bringing in itswake both increased support and enhanceddemands, the phenomenal growth of theMetallurgy and Materials Programme inits three decades of its existence is equallyinevitable. Comprehensive expertise andcore competence have been developed invarious facets of materials science andtechnology such as modeling,manufacturing, testing and complete

MW(e) FBR. This has served a crucialpurpose – at no point of time did researchbecome “Ivory Tower research” – everyoneis sensitive to the fact that all research mustbe useful to FBR and other DAEprogrammes, and in the event of it doesnot, it must be of world class.

The result of such enlightenedmanagement, and also support in theformative years is a group of scientists andengineers with head high up in the sky butfeet firmly on the ground! They arecarrying out high quality research,contributing to DAE programmes, andmaking their mark in the national andinternational arena. They are also daringto dream – to build from strength into newareas not planned earlier. MaterialsSciences Laboratory became part of theMetallurgy Programme in 1985, when Dr.G. Venkataraman left IGCAR after anillustrious career, and Dr Placid Rodrigueztook charge of overall leadership of theMetallurgy and Materials programme. Dr.Kanwar Krishan played an important roleof an affectionate and caring Mentor forMaterials Science activities. In 1992, DrPlacid Rodriguez passed on the baton ofleading the Metallurgy and Materialsprogramme to me, when he took charge asthe Director of this Centre. I have passedon this important responsibility ofnurturing the Metallurgy and Materialsprogramme to Dr. S. L. Mannan in 2004.One must also gratefully acknowledge thepatronage (well earned, one might add!)of Shri C.V. Sundaram and successiveDirectors of this Centre.

I had realized that it is necessary toconsciously guard against complacence, apossible pitfall for any successful researchgroup with national and internationalrecognition, and also enhancecollaboration with competent national andinternational groups with matchinginterests and programmes. I have recentlywritten extensively, in the earlier issue ofIGC Newsletter on the IGCAR-Research-Academia linkage. I have also placedenhanced emphasis on mentoring youngprofessionals, and giving challengingassignments to the mature scientists andengineers. We have recently carried out inour Centre, a detailed mentoring exercisefor young engineers and scientists, to

Programme on the other hand wasspearheaded by Dr. G. Venkataraman,focusing and building expertise in a fewselect areas: nuclear techniques, defect andradiation damage studies, light scatteringand X-rays, and high pressure physics,backed by a theory group. Within a fewyears, researches in low temperaturephysics started with setting up cryogenicfacilities. Strengths of these twoprogrammes gradually increased, with afew transfers from BARC and TIFR, freshinputs from the BARC Training School,and direct selections to the programmes.

There were some common traitsbetween Dr. G. Venkataraman and Dr. P.Rodriguez in their approaches to sciencemanagement – lead from the front, throwchallenges to bright young minds, darethem to dream, and provide every supportfor them to expand their horizons. In thisregard, both bore the unmistakable signsof DAE legacy. Doing one’s Ph.D.working on the departmental projects

became (and continues to be) quitecommonplace in the programmes. Today,Metallurgy and Materials Group has 82Ph.D degree holders, of which more than75% have acquired their PhD degrees fromthe premiere academic Institutes like IITs,IISc, BHU etc, and two even from theUniversity of Saarland, Germany, in thismanner. There was one more, and in manyways a unique, reason for the rapidmaturing of these two programmes. Thisis the continuous interactions with theteams engaged in building the FBTR, andsince the mid eighties, also designing andthen developing technologies for the 500

Today, Metallurgy andMaterials Group has 82Ph.D degree holders, ofwhich more than 75%

have acquired their PhDdegrees from the

premiere academicInstitutes like IITs, IISc,BHU etc, and two evenfrom the University ofSaarland, Germany, in

this manner.

characterization of structural materials.Also considerable experience has beengained in design, construction andmaintenance of hot cells and in-cellequipment in the process of building up astate-of-the-art post-irradiationexamination facility, with equipment such

Success is inevitablewith such a combinationof a dedicated group of

R&D researchers,sensitive about their

mandate, proud of theirachievements, and

always aspiring for more,an enlightened

management, and thesymbiotic interactions.

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present and future FBR and reprocessingplant applications, development of variousadvanced electron-microscopy techniques,development of hard coatings and boridingtechniques for FBR and reprocessingapplications, future radiation detectormaterials, and modeling for structuralsystematics. The facilities include acomprehensive optical and electron-optical laboratory with an analyticaltransmission electron microscope and ahigh resolution transmission electronmicroscope, X-ray diffraction, chemicaland plasma vapour deposition, laserablation, and magnetron sputtering. Thecorrosion studies for fast reactor, powerplant and reprocessing plant applicationsinclude stress corrosion and corrosionfatigue, generalized and localizedcorrosion, high temperature oxidation, bio-fouling, basic studies in surface sciences,surface modification techniques forimproved corrosion resistance, andcorrosion monitoring. Apart from twodynamic liquid sodium loops andcorrosion fatigue machines, allconventional characterization facilities arealso added. Necessity dictated creation, inthe nineties, of a small, dedicated teamdevoted to tackle innovative design andengineering problems like capsules for in-reactor experiments including in-reactorcreep testing, study and modeling ofthermal cycles and residual stresses inwelding, precision machining and weldingof small size components, and generationof precision calibration standards for NDTequipment.

Materials Science Research inIGCAR has earned respect for its solidityand also balanced emphasis onexperiments and theory. The emphasis onindigenous development of research gradeinstruments and experimental set ups ledto several ‘firsts’: a He-Ne laser for aRaman scattering setup, a positron life timesetup which was followed by an angularcorrelation apparatus, Tandem Van deGraaf accelerator, diamond anvil cell forhigh pressure X-ray research, high tonnagepress for studying pressure induced phasetransitions and amorphisation, X-rayspectrometer, an internal friction setup,several liquid nitrogen and heliumcryostats for low temperature physics

Research Centres. The mechanicalproperties assessment laboratories nowhouse a battery of creep testing units,facilities for low cycle fatigue, creep-fatigue interaction and thermo-mechanicalfatigue testing, instrumented drop weightand impact testing units for dynamicfracture studies, and facilities for quasi-static fracture mechanics and fatigue crackgrowth studies at ambient and elevatedtemperatures. The early researches ondynamics of plastic deformationparticularly dynamic strain ageing,mechanistic and predictive aspects ofcreep, low cycle fatigue and creep-fatigueinteractions, and dynamic fracture studiesbrought international recognition. Theinternational popularity of the series offour International Conferences on “Creep,Fatigue and Creep-Fatigue Interaction”hosted so far at a regular interval of fouryears is a testimony to the recognition ofour strength in this field. Today the scopeof research has multiplied manifold,encompassing detailed evaluation of theproperties relevant to FBR technologyparticularly the 500 MW(e) FBR, theirdependence on microstructure, researchesinto fracture and damage mechanics forcurrent and future applications, andnumerical modeling and simulations forcorrelation and extrapolation. Studies inmetal forming and tribology includedevelopment of critical materials, near netshape forming, studies on thermo-mechanical processing, modeling andsimulation for material processing andmicrostructure evolution, and fretting andwear studies for FBR applications. Sincethe nineties, a dedicated group is involvedin the problems of science and technologyof welding and hardfacing for FBR andfuel reprocessing applications. Its scopeof research includes weldability studies,indigenous development of specializedwelding consumables, technologydevelopment for dissimilar metal welding,hardfacing and surfacing, in-situ and off-site repair welding of power plantcomponents, development of ActivatedTIG welding, and intelligent welding.Facilities are being added to tribology andwelding laboratories to meet theseincreasing demands. Physical metallurgyresearch includes comprehensivecharacterization of materials for the

as visual examination, dimensionalmeasurements, eddy current testing, X-radiography, neutron radiography, bothprototype and miniature mechanicaltesting, radiochemical methods etc. Arecent achievement of this facility is theexamination of carbide fuel from FBTRthat has seen a burn up of 100 GWd/t. Bythe late seventies, it was strongly felt thatan advanced expertise base needs to be setup to cater to the ever increasing, and oftenchallenging, existing and anticipated NDErequirements of the DAE family. It wouldadopt and adapt and improve uponconventional techniques, and harness theemerging “esoteric” NDE methods forpractical applications. Commissioning ofthe Kamini reactor for neutron radiographywas only part of the story. Today, theMetallurgy and Materials Programme canjustifiably boast of a world-class schoolfor R&D in NDE research. Its field ofresearch includes conventional techniques,and also advanced techniques like acousticemission, X-ray diffraction, magnetic/acoustic Barkhausen noise, infraredthermography, ultrasonic and eddy currentimaging, residual stress measurements;development of various NDE probes,transducer and instruments for variouscritical applications, and evendevelopment of ferro-fluid based sensorfor magnetic flux leakage measurement.Matching R&D facilities have been set up,making it one of the best such laboratoryanywhere in the world. The range ofapplications is equally impressive: instructural integrity assessment and lifeextension, in-service-inspection (ISI) ofcomponents for heavy water plants;nuclear reactors and fuel cycle facilities;defect and microstructuralcharacterisation; in-situ structuraltransition and defect detection in supportof in-service inspection and intelligentmaterial processing and welding; advancedsignal analysis and development ofknowledge-based decision supportsystems; mathematical modeling/simulation; and image analysis.

The same catalysts can be identifiedfor the spectacular growth andcontributions of the other metallurgicalresearch laboratories. The R&D facilitiesare recognized as amongst the mostcomprehensive amongst other similar

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the area of SQUID technology is that weare collaborating with National Instituteof Mental Health and Neuro Sciences(NIMHANS), Bangalore, in a DST-sponsored project, for setting up of aSQUID based magneto encephalography(MEG) system for non-invasive studies ofhuman brain.

Under the prevailing internationalembargo scenario, building up of thefacilities and expertise has beenchallenging to the utmost. A popular adagesays: “When the going gets tough, thetough get going”. This has always beenthe culture in DAE, and the Metallurgy andMaterials Group is no exception. Oneexample from the early eighties is thesuccessful development of equipment ofhigh reliability for post-irradiationexamination. There are many, many moreexamples of such successes throughout theyears. Comprehensive self reliance,particularly in the critical sectors, hasalways been one of the key guidingprinciples. The successful indigenous

study the same system, backed by rigoroustheoretical studies has led this laboratorybeing internationally recognized as aleader in many areas of research. Theresearch on positron annihilation threwnew light on the early stages of point defectclustering, helium bubbles in metals andalloys and phase transitions in Al alloys.Outstanding research in the area of lightscattering in colloidal systems has lead tothe discovery of phase separation basedon the ionic impurity concentration,opening up a vast area of research. Thehigh pressure research in lanthanide andactinide based alloys and other AB2 typeintermetallics like LaAl2, UAl2 and ThAl2

attracted worldwide attention. The field ofhigh temperature superconductivityspawned a host of research into materialsand properties of YBCO and relatedcompounds. Pioneering work on dopedsuperconductors, and the natural extensionto Fullerenes ensured that this laboratorystayed at the forefront of low temperaturebasic research. Studies with the variableenergy positron beam system for defectstudies at different depths ranging from afew nanometers to microns has thrown newlights on the phenomenon of irradiationembrittlement of steels and metal-semiconductor junctions. SIMS is beingused for many critical studies includingcarbon and nitrogen profiles in austeniticstainless steels, phenomenon ofimplantation, and diffusion in thin films.Researches in theoretical physics havebeen equally outstanding. For example,application of novel techniques likefluctuations and non-linear theories gavenew insights into defect and theirinteractions. The theory of “defectordering” was initiated using the principlesof fluctuations and bifurcation. Anexciting new area of study undertaken isthe application of Monte Carlo techniquesfor porous media. The expertise developedin experimental physics has proven to becrucial in the success in manydevelopments in areas of technical physics:SQUID - based technology for basicresearch and NDT, image plate scanner forfilmless radiography, and development ofMicro-Electro-Mechanical Sensor(MEMS) - based ultrasonic transducers fora NDT applications. A recognition of theformidable strength and achievements in

studies. In the early years, Dr. K. P.Gopinathan had played a key role in theindigenous nuclear spectroscopydevelopmental activities. This aspect ofself-reliance has been a guiding factor inthe subsequent phenomenal growth of allthe facilities. For example, the particleirradiation facility that started with aneutron generator today houses 1.7 MVTandetron Accelerator, various facilitiesfor ion implantation, Rutherford BackScattering (RBS), Channeling, ParticleInduced X-ray Emission (PIXE), and HallEffect measurements. Some of the otherunique and world-class facilities are: anindigenously developed variable energypositron beam system, a very sophisticatedX-ray diffractometer with low and hightemperature attachments, novel materialssynthesis under megabar pressures andhigh temperatures etc. Subsequently,thermal desorption on alloys andcompounds was another new area ofresearch which catapulted the research intothe area of sputtering and surface science.A Secondary Ion Mass Spectrometer(SIMS) was installed to look at depthresolved compositions in metals and alloysat sensitivities in the ppb level. In courseof time, important activities have beenadded to the materials science researchprogram. In the mid-eighties, it wasdecided to considerably expand the scopeof research on superconducting materials,to encompass both basic research in theemerging exciting field of hightemperature superconductivity, andsuperconducting quantum interferencedevice (SQUID) based sensordevelopment. This necessitatedcomprehensive expansion in the facilities,including fabrication facilities for micro-fabrication for feature sizes down to 1micron, and for thin film based SQUIDfabrication, and laboratory for devicecharacterization and utilization. Dr. T.S. Radhakrishnan had caringly nurturedthese SQUID application activities, as wellas provided leadership for materialsscience programme. Subsequently, Dr. B.Viswanathan took over the mantle ofMaterials Science activities and jump-started the accelerator-based radiationdamage programme on reactor alloys.

Application of a variety ofexperimental and theoretical techniques to

The most hearteningaspect of the programme

is that technologicalopportunities have led to

“science”, i.e., basicunderstanding, as

reflected in numeroushigh quality research

publications in reputedjournals and important

conference proceedings,earning prestige for theindividuals scientists as

well as the researchgroups, which are now

internationallyrecognized.

development, in collaboration withindustry, of austenitic SS 316L(N),modified grade 9Cr-1Mo (P91), andASTM A48 P2 steel plates, and also thewelding consumables for the SS 316L(N)and P91 grades, with properties matchingor excelling those for the internationallyavailable products, are recent examples ofthis approach. Most of the research

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Since many of thefacilities available are

rare, if not unique in thiscountry, we have beenwelcoming and indeed

encouraging theirutilization by scientists

both within DAE andoutside DAE, particularlythe student community.

This has alsoconsiderably

strengthened theinteractions with otherreputed institutions.

programmes in metallurgy were undertakento meet immediate and specificrequirements for the 500 MW(e) FBR andthe fuel reprocessing technologies. In turn,as the pioneers envisaged, thecontributions from this Group have beenoutstanding from its very inception. Overthe years, the contributions cover everyfacet involving metallurgy and materials:materials selections, indigenousdevelopment of special materials,development of melting and fabricationroutes, characterization of creep, fatigue,fracture, corrosion, and tribological andfretting properties, life prediction andextrapolation, welding and hard-facing forthe FBR components, development ofspecialized techniques for pre-service andin-service inspections, robotics andautomation, the examination of fuel pinsirradiated in FBTR, and computationalmodeling. The most heartening aspect ofthe programme is that technologicalopportunities have led to “science”, i.e.,basic understanding, as reflected innumerous high quality researchpublications in reputed journals andimportant conference proceedings, earningprestige for the individuals scientists aswell as the research groups, which are nowinternationally recognized.

The rapidly growing expertise ofthese programmes have been recognized,and sought after, by the entire DAE familysince the very early days. An example fromthe early eighties is the instrumentedimpact testing of irradiated Charpyspecimens of ASTM 203 Grade D steel(the initial RAPP end shield material); thiswas carried out in the fracture laboratoryof IGCAR, the first time such test has beencarried out in the entire DAE family.Indeed, from the very inception,Metallurgy and Materials Group has beenmaking available its expertise to variousunits of DAE like Nuclear PowerCorporation, Heavy Water Board, NuclearFuels Complex etc. in various areas likeintegrity assessment and NDE, lifeassessment and rejuvenation, failureanalysis, welding metallurgy and in-siturepair welding, and specialized testing andconsultation. The recent in-reactor creeptesting of Zircaloy carried out in FBTR isone more link in the same chain. Theexpertise of the NDE group has found its

use in such diverse and critical areas likeNDE based damage and fitness-for-purpose evaluations and life extension ofengines, aircrafts and helicopters of thenational defence sector, and of rocketmotor casing, satellite tanks etc. for thenational space program, archeo-metallurgyand national heritage preservation, andeven in small scale industries. Theexpertise of other research groups are being

and international, has come to young andnot so young scientists and engineers inthe Group in good measure. What howeverI wish to specially mention is the honours,in the form of DAE Meritorious ServiceAwards, to many of the supportingtechnical staff: S/Shri T.M. MohamedKoya, K. Jayakumar, C. Balan, S. FrancisRajan, N. Chellam Thevar, (Smt.) M.Radhika, A. Vincent Paul Raj, and M.Kuppusamy. This is an indication of theR&D environment prevailing in the group.It also underscores a factor often ignored:the supporting technical staff has to benurtured to play a key role for anyambitious R&D programme to succeed.

If one has to identify the one factorthat is responsible for the glorious successof the Metallurgy and MaterialsProgramme in thirty one years of existence,it is the ability to harmoniously synthesizethe twin roles of operating in the “researchmode” and the “mission mode”. This hasinculcated a tremendous sense of

If one has to identify theone factor that is

responsible for theglorious success of theMetallurgy and MaterialsProgramme in thirty oneyears of existence, it is

the ability toharmoniously synthesize

the twin roles ofoperating in the

“research mode” and the“mission mode”.

responsibility to IGCAR, DAE and thenation without curbing scientificaspirations in any way, promoted teamwork, and led to R&D that is both relevantand excellent. This is also the reason forthe youthfulness of the Group: it is nowthirty one years young, and I have nodoubt that as long as the members of thisGroup do not lose sight of this basic fact,and dare to dream, it will continue to beyoung for many more decades to come.

Baldev Raj(Director)

sought from time to time by NationalThermal Power Corporation, thepetrochemical sector etc. in critical issues.As I have recently described in these pages,the various laboratories in the Group havebeen actively participating in manyimportant collaborative efforts with severalleading academic and research institutesin India as well as in France, Germany andthe United States under variousprogrammes sponsored by IGCAR, DAE,Board of Research on Nuclear Sciences(BRNS), Department of Science andTechnology (DST), and variousinternational bi-lateral collaborations.Since many of the facilities available arerare, if not unique in this country, we havebeen welcoming and indeed encouragingtheir utilization by scientists both withinDAE and outside DAE, particularly thestudent community. This has alsoconsiderably strengthened the interactionswith other reputed institutions.

It is quite natural that with suchstrength and reputations, recognition in theform of honours and awards, both national

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void swelling and irradiation creep wasdetermined by finite element analysis usingsoftware CAST3M, issued by CEA,France.

If the GP had been free at theperiphery, it would have deformed freely

Analysis of Grid Plate towardsremaining Life Assessment ofFast Breeder Test Reactor

The SP carries the entireload of SA while GPprovides guide to maintainthe verticality of the SA.The mechanical load actingon the GP is negligible.However, the GP sees highneutron irradiation in thehybrid core configurationto the order of 1.72x1021

n/cm2/y, compared to theflux of 2.69x1020 n/cm2/yfor SP. Thus GP is critical w.r.t neutronirradiation, and is analysed for variousfailure modes viz. loss of ductility,accumulated inelastic strain due toconstraints of free expansion and overalldeformation of plate, which in turn affectsthe verticality of the SA, the frictional forceat the button and handling operation dueto excessive tip displacement. The loss ofductility has been derived from theliterature depending upon the accumulatedfluence and the plate deformation due to

Fast Breeder Test Reactor (FBTR) isoperating with 28 Mark I fuelsubassemblies, 13 Mark II fuelsubassemblies and 1 PFBR fuelsubassembly (FSA). As a long-termmeasure, it is now proposed to use a hybridcore (26 Mark I subassemblies in thecentral core surrounded by 52 MOXsubassemblies). The actual doseexperienced by the grid plate so far isequivalent to the dose that would havebeen experienced with hybrid fuelledreactor, operating at 30.7 MWt over aperiod of 0.5 Effective Full Power Year(EFPY). A detailed analysis has beencarried out to assess the remaining life ofgrid plate.

In the reactor assembly (Fig.1), thegrid plate structure does the importantfunction of supporting and guiding thesubassemblies (SA) and also the entry ofsodium in to the core. This structureconsists of support plate (SP) and guideplate (GP), joined by an intermediate shell.The material of construction is SS 316.

under irradiation swelling. The end stiffnessprovided by the intermediate shell at theouter periphery, results in bending of GP.The free bending is restricted by thepresence of control rod support sleeves,which is clear from the deformed shape(Fig.2). In this process, the sleevedevelops a tensile load of 9710 N. Themaximum vertical displacement of the GPis 1 mm. The inner portion of GP deformsdownwards while the outer portiondeforms upwards. This leads to

Fig.1: Reactor assembly

Fig.2: Deformed shape of GP after 20 EFPY

Fig.3: Von-Mises stress distribution without consideringrelaxation during 20 EFPY

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compacting of the inner sub assemblies andflowering of the outer sub assemblies.

The neutron irradiation causes a lossof ductility in stainless steels. The designlimit of 10% total elongation at the end oflife is considered, to safe guard againstbrittle fracture. Accordingly the acceptabledose is 2.0x1022 no / cm2. The fluence ofthe GP is 1.717x1021 no/cm2 per year, andthe corresponding safe period is 11.5EFPY.

For the structural material, havingdose rate <5 dpa, the cumulative strainlimit is 1.0%. In the hybrid core, theneutron dose seen by the clad for the targetburnup of 150,000 MW d/t is 76 dpa. Forthe clad material, the thermal creep strainand plastic strain limits during steady stateand transient operation should be 0.2 and0.3%, respectively. Since the GP dose ratefalls below the dose rate of clad materialand above 5 dpa, the allowable strain limithas been interpolated as a function of timebased on the accumulated dpa. The

Fig.4: Accumulated strain variation

Fig.5: Deformed shape of a typical SA(After 20 years)

accumulated strain in the GP at any pointof time shall not exceed this allowablelimit.

The Von-Mises stress distribution inthe guide plate at the end of 20 yearswithout any creep relaxation is shown inFig.3. It is used for computing theaccumulated strain as a function of time.The allowable strain limit and theaccumulated strain as a function of timehave been plotted in Fig.4. Based on thisthe safe operation is arrived as 48 EFPY.

The tip displacement of control rodSA is obtained by separate analysis (Fig.5).The allowable life is 18.5 EFPYcorresponding to 0.84 mm tipdisplacement (allowable slope of 5x10-4).Total allowable misalignment for core SAis 6 mm from the fuel handlingconsideration. A value of 1 mm isapportioned to account for the tipdisplacement of SA due to the swelling ofguide plate and the correspondingallowable life is 22 EFPY.

Because the displacements areconstrained at the button location, theresulting reaction forces produce frictionalforce of about 25 N, which is less than theallowable value 1000 N for ensuringsmooth fuel handling operation. Hence itis not governing the life.

Based on the above conservativeinvestigation, it is concluded that FBTRcan operate still for a period of 11 EFPYusing hybrid core. However, longer life ispossible by reducing the fluence throughprovision of enhanced shielding at thebottom of SA. It is also recommended tointroduce surveillance coupons atappropriate locations to determine theradiation damage.

(Reported by R.Suresh kumar,R.Srinivasan, P.Chellapandi and

S.C.Chetal, Reactor EngineeringGroup)

“… There is a need for a constant interplay between basic sciences, technology and industrialpractice if economic progress is to result from the activity undertaken. The wearing of severalhats by the same person and the mobility of personnel from one type of activity to anotherhave provided the impetus for growth in the projects of the Department of Atomic Energy… “

- Vikram A. Sarabhai

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The structural integrity of austeniticstainless steel components is affected byvarious material degradation processessuch as intergranular corrosion (IGC),stress corrosion cracking (SCC), pittingcorrosion, creep and fatigue damage. It isessential to detect and evaluate thedegradation by periodic inspections of thestructural materials and components inoperating plants either on-line or duringshutdown. Sensitisation of austeniticstainless steels (SS) is a major problemduring welding or high temperatureservice. It occurs when austenitic SS isheated or cooled slowly in the temperaturerange of 723 to 1123 K, which causesdepletion of chromium (Cr) to less than12% in the region adjacent to the grainboundary due to the precipitation of acontinuous network of Cr-rich M23C6

carbides. In molybdenum (Mo) containingaustenitic SS, these Cr-rich M23C6 carbidesalso contain Mo, thus causing a depletionof Cr+Mo in the grain boundary regionduring sensitisation. When a sensitisedstainless steel is exposed to a corrosiveenvironment, these depleted grainboundary regions dissolve, leading to ahost of corrosion problems such as IGCand intergranular SCC (IGSCC).

ASTM standardised tests (ASTMStandard A 262 Practice A to F), whichare chemical in nature, are used to evaluateIGC caused by sensitisation in austeniticSS. These tests are commonly used toqualify/accept a component duringpurchase/fabrication stage. However, non-inclusion of acceptance limits in thesestandards leaves the interpretation ofresults open to users. Besides notquantifying the degree of sensitisation(DOS), these tests are also destructive andslow – a situation that is not welcome at

plant site. To overcome these limitationsof chemical tests, an electrochemicaltechnique, known as electrochemicalpotentiokinetic reactivation (EPR)technique, was developed andstandardised by ASTM (ASTM G108) toquantify DOS. This is a quantitative, non-destructive and rapid method, which isessentially suitable for field use. The EPRtechnique provides a criterion to identifythe complete absence of sensitisation and,thus, is useful in quality control offabricated components. However, it doesnot readily provide an acceptance criteriaif a certain DOS is present in the material.Despite all efforts, EPR technique has notshown much of its early promise as a toolfor quantifying DOS. This is because of(i) its high sensitivity to the changes inchemical composition of the SS, and (ii)inconsistencies in the correlation betweenASTM Practice A262E and EPR DOSresults due to effects of aging temperature,which does not permit a threshold DOS tobe defined. These drawbacks in the EPRtechnique call for applying alternate NDTtechnique to unambiguously quantifyDOS. Eddy current testing (ECT) presentsa viable alternative due to its high sensiti-vity to changes in electrical conductivity/permeability. We describe a laboratorystudy wherein an attempt was made todetect and quantify DOS and IGC in AISItype 316 SS by the ECT technique. In thisstudy, heat treated rectangular specimensof AISI type 316 SS were subjected toASTM A262 Practices A and E tests, EPRtests and ECT tests. Optical microscopicexamination in as-polished condition afterexposure to Strauss test solution was alsocarried out to determine the depth of attackby the Strauss test solution.

Bend test, after exposure to modifiedStrauss test solution, was used as acriterion to categorise the DOS, which wasthen correlated along with themicrostructures to the values of EPRparameters and EC amplitude. Here itwould be important to mention that in theoxalic acid etch test (ASTM A262 PracticeA test), the M23C6 carbides are dissolvedon electrolytic etching, while in modifiedStrauss test solution, the chromium deletedregions are attacked and not the M23C6

carbides. In oxalic acid etch test,qualitatively three microstructures arepossible viz. ditch structure correspondingto continuous M23C6 carbide precipitation,dual structure corresponding todiscontinuous M23C6 carbide precipitationand step structure corresponding toabsence of M23C6 carbides. Based on theappearance of the bent region, the agedsamples were categorised as (a) unaffected,(b) fissured, (c) cracked, and (d) broken.Figure 1 shows the different categorieswith corresponding microstructures. It isseen that for specimens that were brokenor cracked, a ditch structure was seen;while for fissured specimens, a dualstructure was observed. Unaffectedspecimens showed two types of structureseither a step structure or a fully ditchedstructure. Aged specimens which showedditched structure remained unaffectedduring bend test since the grain boundaryCr-depletion is self-healed with time bydiffusion of Cr to the grain boundary areafrom the bulk of the austenite grains.Examination of as-polished surfacesexposed to Strauss test showed grainboundary attack to a certain depth only inthe cracked or broken specimens, as shownin Fig. 2, with the depth of attack beingmore in the latter.

Detection and Evaluation of Sensitisationand Intergranular Corrosion in Austenitic

Stainless Steels by

Eddy Current Testing Method

99999

Category based on microstructure

Fig. 1: Categorisation of DOS based onbend test after ASTM A262 Practice E test and

corresponding microstructures

1010101010

The results of EPR tests, depth ofattack and ECT corresponding to thevarious categories are detailed in Table 1.The EPR tests were carried out by thedouble loop technique because this methodautomatically compensates for changes inalloy composition and also for differencesin surface finish. The ratios of peak currentdensities during reactivation (Ir) toactivation (Ia) and reactivation charge (Qr)to activation charge (Qa) were used asassessment parameters to evaluate DOS.Table 1 shows the range of the ratios ofQr/Qa and Ir/Ia for unaffected, fissured,cracked and broken categories of DOS. Asper the standards prepared by InternationalStandards Organisation (ISO) forevaluation of IGC susceptibility by meansof double loop EPR test, values of Ir/Ia *100 > 5 show medium to strongsusceptibility to IGC. Based on this, it canbe inferred that the aged specimens thatshowed fissures or remained unaffectedafter bend tests were not sensitised. Figures3 (a) and (b), which represent the EPRcurves for the cracked and brokencategories of specimens, show that onactivation potential sweep, a shoulderanodic to the main activation peakoccurred. However, such a shoulder wasnot seen in the material that showedfissures or remained unaffected. Thecurrent density of the shoulder nearlycorresponded to the peak current density

of the reactivation peak, indicating that theshoulder occurred due to dissolution ofCr+Mo regions. Also, the peak currentdensity of the shoulder was higher in thecase of broken specimens than crackedspecimens.

Fig. 2: Micrographsshowing depth of attackcaused by the Strausstest solution in(a) specimens showingcracks, and(b) in broken specimens

The eddy current (EC) signalamplitudes from various specimens in theas-aged condition (prior to Strauss test) areshown in Fig. 4 and Table 1. It is seen thatthe overall change in the amplitude amongall the specimens was small i.e. about 0.75V with a maximum scatter of ±0.008 V.This was due to a small change inconductivity/permeability by the depletionof Cr adjacent to grain boundaries whichcaused local increase in the Ni content thatresulted in increased magneticpermeability of the material. Figure 5 andTable 1 show that the overall change inthe EC amplitude among all the Strauss-tested specimens was of the order of 8.0V, which was much higher than thatobserved for as-aged specimens. This wasbecause of the dissolution of Cr depletedregions and the consequent grain boundarygrooving that occurred during Strauss test.Grain boundary grooving causes enhancedperturbation of EC flow which, in turn,leads to increased impedance change i.e.signal amplitude. The fact that unaffectedspecimens also included those withcontinuous grain boundary carbide

Fig. 3: Doubleloop EPR curves

for type 316stainless steel

that (a) showedcracks, and (b)was broken, in

bend tests

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Fig. 4: EC responses from the as-aged condition specimens arein good agreement with the four categories of specimens

classified after bend test

Fig. 5: Comparison of EC responses from the Strauss testedspecimens with severity of the damage developed after bend

test

Table 1: Bend test, EPR, depth of attack and eddy current testing results at a glance

No. EPR Results EPR Results Depth of EC response Category of the specimenIr/Ia (%) Qr/Qa (%) attack (mm) (Volts) (after bend test)

As-aged Strauss testedspecimen specimen

1 0.02 0.16 — 0.0 0.0 Not affected

2 0.27 0.18 — 0.012 0.12 Not affected

3 0.25 0.17 — 0.012 0.13 Not affected

4 0.24 0.18 — 0.012 0.12 Not affected

5 0.011 0.17 — 0.012 0.13 Not affected

6 0.011 0.15 — 0.012 0.12 Not affected

7 0.009 0.22 — 0.012 0.12 Not affected

8 0.29 0.04 — 0.015 0.27 Not affected

9 0.89 3.95 — 0.17 0.62 fissures

10 0.92 1.98 — 0.15 0.8 fissures

11 1.38 0.96 — 0.17 0.82 fissures

12 0.77 0.45 — 0.15 0.75 fissures

13 0.52 0.38 — 0.15 0.72 fissures

14 5.6 5.86 75.0 0.21 2.43 cracks

15 12.15 17.86 147 0.30 6.22 cracks

16 5.62 6.18 79.8 0.35 3.18 cracks

17 18.15 20.01 154 0.40 6.5 cracks

18 14.2 26.7 104 0.35 6.4 cracks

19 5.56 12.23 92.1 0.30 4.2 cracks

20 20.87 36.11 103 0.49 6.7 cracks

21 56.8 67.2 308 0.65 7.85 Broken

22 37.6 59.1 190 0.62 7.5 Broken

1212121212

to bend test. The impact of this would befelt during monitoring of the SScomponents in service by providing vitalinformation on the initiation and progressof IGC/IGSCC. Also, ECT could be usedas a reliable tool to ensure quality offabrication against sensitisation. Thiswould help fabricators and the users toguard against sensitisation, particularly inapplications where fabrication costs are

linked to DOS. However, for this to befeasible, proper optimization of EC testparameters, precise calibration andsystematic and reliable measurements areimportant pre-requisites.

(Reported by: B.P.C. Rao & H. Shaikh,Non-Destructive Evaluation Division,

Corrosion Science and TechnologyDivision, Metallurgy and Materials

Group)

precipitation but self-healed indicated thatcarbide precipitation per se had little orno role in affecting the conductivity/permeability of the steel.

A very important and potentialapplication arising from the present studyis that by knowing the EC signal amplitudefor different category specimens, thepropensity to and extent of IGC could beassessed without subjecting the specimens

Chloride concentrations, used in thepresent study at different depths in P1 andP2, were reported by BHAVINI. Thechloride level in the freshly built layersconsisting of 100 mm of PCC i.e. concretewith 30% fly ash followed by normalstructural concrete (Stage V) was 0.05 kg/m3. However, it was necessary to ascertainthat an increase, if any, in chlorideconcentration in the structural concrete dueto diffusion from the underlying layers,would be within the permissible limit evenafter 150 years.

The redistribution of chloride withinthe structure occurs essentially by adiffusion process. One-dimensionaldiffusion equations were set up withappropriate initial concentrations andboundary conditions, and solved usingNumerical methods to obtain the chlorideconcentration at the required distance andtime. The inputs required for the abovecalculation namely the initialconcentrations of chloride and diffusioncoefficients of chloride in concrete (Dc)and fly ash containing concrete (DPCC) weretaken from the BHAVINI report andliterature on similar type concreterespectively. The predicted chlorideconcentrations are shown in Fig. 2. It isseen that the chloride concentration isalways well below the allowable limit onthe surface of fly ash concrete (Fig. 2(a))and also in the entire concrete structureeven after 150 years (Fig. 2(b)).

Prediction of Chloride Redistribution inConcrete Structure of PFBR

estimated concentration profiles. Thesestudies were carried at Physical MetallurgySection in collaboration with ParticleIrradiation Facility and Theoretical StudiesSection, MSD, with inputs fromBHAVINI.

Prediction of chlorideconcentration in the concretestructure, during its servicelife:

The problem is representedschematically in Fig.1, where inundationof seawater on the concrete structure ofPour 1 (P1) and Pour 2 (P2) is illustrated.

The entry of seawater into the PFBRconstruction site at Kalpakkam, onDecember 26, 2004, during Tsunami,entailed a detailed study on the extent ofchloride ingression into the concrete thathad been laid and its consequences on thesubsequently built layers. It was necessaryto assess whether the chloride content inthe newly built concrete would be belowthe allowable limit of 0.6 kg/m3 (as per IS:456-2000), even after 150 years. Thestudies included prediction ofredistribution profiles of chloride in theconcrete structure up to 150 years and anassessment on the reliability of the

Fig. 1 Schematic Elevation View of a section of the concrete built-up

1313131313

Reliability assessment of theconcentration profiles:

The concentration profile in Fig. 2was evaluated using diffusion coefficient(D) values from literature. Hence,validation of the selection of D values andexamination of the sensitivity of theconcentration profiles to possiblevariations in D were essential. Anextensive compilation of reported D valueswas examined. The D values were foundto be in the range of 10-14 to 10-11 m2/sec,representing various types of concrete,exposure conditions, and testing methods.The concentration profiles evaluated byanalytical method, as a function of time(up to 150 years) at a distance of 100mmabove P2 using a range of D values areshown in Fig 3. It can be seen that theconcentration always remained below thepermissible level of 0.6 Kg/m3, for even a‘D’ value as high as 10-9 m2/sec, which istwo orders of magnitude higher than thehighest value reported in literature and canbe considered to represent an extremesituation.

Factors leading to high ‘D’,representing an extremescenario:

A concrete block (150mm cube) thatwas mixed using normal water but wassubsequently cured in seawater for 20 dayswas obtained from BHAVINI.Microstructural and microchemical detailswere obtained from specimen from thisblock using an Environmental ScanningElectron Microscope attached with an X-ray Energy Dispersive Analyzer.

The block exhibited a typicalmicrostructure (Fig. 4(a)) consisting of aninhomogeneous dispersion of aggregatesof different shapes and sizes, the bindingmedium of hydrated cement paste and aninterface (of ~ 2-5 m) between cementand aggregates. Micro chemical analysisof the specimen showed chloride to bepreferentially present in the cement phase.During curing, water reacts with tricalciumsilicate mineral to form the poroushardened cement paste and chloride

Fig. 2. Chloride Concentration profile in concrete as a function of (a) time at thesurface of PCC (b) depth after service life of 150 years

Fig. 3. Calculated Chloride Concentration Profiles as a function of time at surface ofPCC (100mm above P2) for different ‘D’ values

1414141414

species exist predominantly within thepores of the cement phase. Figure 4(b)shows an EDS spectrum from the cementregion of the specimen. The intensity ofChlorine-K peak at the surface of theseawater cured concrete is higher than thatof the normal water cured concrete, whilethe peak could not be detected at a depthof about 75mm in the seawater curedblock.

Chloride concentration measured byProton Induced X-ray Emission (PIXE)technique on specimen from differentdepths of the seawater cured block isshown in Figure 5. It is seen that the netintensity of chlorine at the surface of theblock and up to a distance of 35-40 mm ishigher than that at larger distances or atthe center of the 150mm block. The Dvalue obtained by fitting the abovechloride concentration profile is ~1.8 x 10-

9m2/s, which is higher than values reportedfor cured concrete ~ 10-13-10-11 m2/s.

The above experiment shows thathigh value of D was obtained in a concreteexposed to seawater during initial stagesof curing. The high rate of chloridediffusion in seawater cured concrete is dueto the undeveloped pore system in the wetconcrete, in the initial stages of hydrationof cement. This diffusion process, inprinciple could have proceededindefinitely, but for the simultaneoushydration process of cement, whichhardens the concrete introducing animpermeable, tighter pore system arrestingfurther ingress. However, in cured concretestructures such high rates of diffusion arenot expected during service. Calculatedconcentration profiles in Fig. 3 have alsoshown that the chloride concentration isbelow the allowable limit up to 150 yearsfor value of D as high as 10–9 m2/sec.

These studies lead to the conclusionthat chloride content on the surface of thePCC layer would always be below theallowable limit.

(Reported by: T.Karthikeyan, S.Sarojaand M. Vijayalakshmi, Physical

Metallurgy Section, MaterialsCharacterisation Group)

Fig. 5 Chloride profile by PIXE Analysis of specimen from different depths of theconcrete block cured in sea water (x=depth from surface).

Fig. 4 (a) Microstructure of concrete cured in seawater (b) EDS spectra for seawatercured concrete surface vs. center compared with reference cured in normal water.

1515151515

The mechanical design and thicknessof the foils were optimized based on a largenumber of tests in water. Fig. 2 shows thetest set up. The tests were carried out atambient temperature in the hydraulic loopof Fast Reactor Technology Group. Mildsteel pipe of OD 406 mm was used for setup. In this set up, all the three foils wereinstalled inside the pipe at a uniform gapof 10 mm and at 60° apart so that all thefoils had no physical contact with respectto each other. To electrically insulate eachof the foil from the pipe, two MICO sparkplugs were installed in the pipe. The MICOspark plugs were installed in the pipe withthe help of sleeves. A holder, which iswelded to the central electrode of the sparkplug, was used to hold the foil. A Perspexwindow was provided at the top of theflange to see the foils after impact of water.For testing, foils were kept at a distance of140 mm from the point of application ofhydraulic pressure. Electronic connectionswere given to the terminals of the sparkplug.

The cross-wires were tested forsudden flow. Water was admitted into thetest setup by sudden opening and closingof a ball valve. This pressurized watermakes impact on these foils causing themto snap. The pressure required for snappingwas recorded. A dynamic pressuretransducer was installed to measure thepressure of water at the time of opening ofthe ball valve. Testing of foils was also

Development of Cross WireType Leak Detector

been provided on the foils to give aminimum breaking pressure. These foilshave to break when sodium and its reactionproducts passes over them.

All the three foils are insulated fromeach other and are placed in such a waythat there is no physical contact betweenthem. The resistance of the foil iscontinuously measured using theelectronics. In case of a rupture disc burst,the high pressure breaks the foils resultingin sudden jump in resistance. Theelectronics senses this change in resistancewhich gives alarm signal indicating thatsodium water reaction has taken place inthe steam generator. This type of leakdetection technique is a unique attempt forSG’s of FBR’s.

The electronics for the leak detectionsystem comprises of individual circuits foreach of the foils. The leak detector modulesare supplied with constant voltage throughthe foils. The comparator in the circuitcompares the output from each foil to thefixed set point and 2/3 logic determines thebursting of rupture disc. The developmentof CWLD involves optimizing thethickness of the foils and determinationof breaking time for snapping technique.

Double ended guillotine rupture ofSteam Generator (SG) tube resulting inlarge amount of water leaking into sodiumis a design basis event for fast breederreactors. Hydrogen generated in theprocess, sets up a pressure wave andrupture discs are provided at the entry andexit sodium headers, to relieve thepressures into a confined storage tank alongwith reaction products. The failure of therupture disc is generally detected by a sparkplug type leak detector on the downstreamwhich then initiates the other safety actionson the plant. It was desired to improve thereliability of detection of rupture discfailure by a diverse means. Towards this aCross Wire type Leak Detector (CWLD)has been developed and tested at thelaboratories of the Fast Reactor TechnologyGroup.

CWLD comprises of three numbersof stainless steel foils located in cross wirefashion placed downstream of the rupturedisc as shown in Fig.1. V grooves have

Fig 1 a CWLD foils

Fig 1 b Foils after breaking Fig.2 Test setup with electronics

1616161616

Depth of V notch : 6 mm(i.e. 3 mm of foil widthbetween two oppositeV-notches and includeangle of 60o)

Fig. 3 Breaking pressure at different trials

SS foil specification

Length of foil : 338 mm

Width of foil : 15mm

Thickness : 50 micron

carried out by varying the depth of the V-notch grooves. The depth of the grooveswere varied from 5mm to 6mm keepingthe width & thickness of the foil and V-notch angle of 60° constant. The foils hadbeen tested a number of times to check thereproducibility of the breaking pressure(Fig 3).and it was found that the foilssnapped between a pressure of 1.25 kg/cm2 (0.125 Mpa) and 2.8 kg/cm2 (0.28Mpa). It corresponds to a velocity of 2 m/s in the test set up. The minimum pressureand velocity of reaction products in PFBRis 0.37 Mpa and 2 m/s respectively.

The breaking pressure required forsnapping the foils depend on the pre-tension in the foil. A higher pre-tensionimparted to the foils while tighteningcauses the foils to snap at lower pressures.If installation of foils are not proper it canalso lead to improper breaking pressures.Due to the impact loading the foils whichare not installed properly get deflected andthe breaking pressure is found to be larger.

With these experiments, the CWLDfor PFBR steam generator has beensuccessfully tested. The specification ofthe CWLD to be employed in PFBR hasbeen finalized as follows:

FBTR20

CONFERENCE ANNOUNCEMENTS

Twenty years of FBTR Operation

FBTR went critical on 18th October 1985 and will be completing twenty years of operation on 18th October 2005. Beingthe forerunner to the second stage of our nuclear programme, it is proposed to celebrate this event in a fitting way. By thattime, the Mark-I fuel would also have crossed a record value of 150 GWd/t, the highest for any driver fuel.

To formally mark the start of the celebrations, a seminar in Tamil will be held on 18th October 2005, with participationby the employees of FBTR on the significant technical jobs executed by them. On 23rd October 2005, there will be an ‘open-house’ for the family members of FBTR employees.

This will be followed by a get-together of all unit heads of DAE, Ex-chairmen, ex-directors of IGCAR and retiredofficers / employees, who contributed to FBTR both at the project and operational stages. This is presently slated for February2006.

Subsequently, it is proposed to have a two-day technical seminar covering the operational history and system performanceof FBTR. The proceedings would be subsequently compiled and released as CD & book, to serve as a landmark exercise inknowledge management. It is also proposed to bring out a documentary film on FBTR, and a book giving the reminiscencesof retired senior officers of the department.

(Reactor Operation & Maintenance Group)

(Reported by Sudhir T.Ninawe and P.L. Valliappan,Components and Instrumentation Development Division)

1717171717

Parallel computing facility establishedat RSD using a distributed memory Linux Cluster

(Reported by N.V. Muralidharan, C.V.Srinivas &R.Venkatesan, Radiological Safety Division)

A cost-effective high performance scalable Linux cluster computing system has been successfullycommissioned at RSD for implementing a parallel real time atmospheric dispersion forecast model.The system comprises of off-the-shelf physical elements and open source software (Fig.1, Table 1). Inthe present configuration, hyper-threading is enabled in duel Xeon processors (each has 4 logicalprocessors) so that a the 8 + 1 node cluster could provide up to 36 logical processors for executingthe Distributed Memory program.

In order to estimate the cluster performance, the system speedup is tested with a MMS atmosphericmodel as well as a (transpose) benchmark program; MM5 is based on Monte Carlo algorithm andmatrix multiplication using OCTAVE Parallel programming library. Preliminary result on system speedup is shown in Fig.2.

Features of the Cluster at RSD

Debian LINUX with precompiled softwarebundles for easy installation

OS installed using single CD independentlyin all computers

Software KNOPPIX verity chosen for latestand universal hardware detection as well asscientific computing software modules

MPICH installed for message passinginterface for parallel programs

Password-less login across the nodesenabled through SSH for each user

Commercial Split AC used for thermalmanagement

System in continuous operation

1818181818

V-I curves for different modes ofelectrorefiner operation.

The thermodynamic model

The model is based on thethermodynamic equilibria that can beenvisaged between pairs of metals in thespent metal fuel and their chlorides in thesalt . For example, the equilibrium betweenuranium and plutonium will be

UCl3 (salt) +Pu(Cd) PuCl3(salt)+U(Cd)

The activity based equilibriumconstant Keq governs the distribution ofthe metals between the liquid metal phaseand the salt phase. Depending on theconcentrations of U and Pu in the initialfeed to the electrorefining cell, the liquidcadmium anode (LCA) may be (a).Unsaturated with U and Pu, (b). Saturatedwith U but unsaturated with Pu, (c).Saturated with Pu but unsaturated withU, (d). Saturated with both U and Pu. Withgradual electrotransport of the fuel materialfrom the LCA to the the LCC(liquidcadmium cathode), the latter may getsaturated with either U or Pu or with bothU and Pu. One can envisage 16 possiblecombinations of the anode and cathode.The simulation of the electrorefiner

Modelling theElectrorefining Process

solutions. Minor actinides, such as Np,Am and Cm are expected to be depositedalong with U and Pu, get recycled and thusbe transmuted in FBR’s.

Modelling the electrorefiningprocess

The importance of modeling of aprocess is three fold- firstly, to verify theexperimental conditions; secondly, to seethe behaviour of the system underconditions that may not be achievable inthe laboratory or plant and thirdly, tooptimize the parameters to get maximumpossible output from the system understudy which will be useful for scaling upthe process to industrial scale. The abilityto predict the process outcome using themodelling saves a lot of time and energy tobe spent in carrying out the process athigh temperatures of the order of 773 Kunder high purity inert atmosphererequired for handling molten salts and theactinide metals.

Several research groups havedeveloped numerical codes for the moltensalt electrorefining process. Based on thethermodynamic model of Johnson,Ackerman of ANL developed the codecalled PYRO that was written in PASCALand was based on thermodynamicequilibrium considerations. Researchgroups at CRIEPI, Japan have developedTRAIL and PALEO codes based on adiffusion model. These models work verywell at low current densities but thepredictions based on these models degradeat higher current densities, when kineticfactors become important. Recently,Ahluwalia et al. have developed the codeGPEC to determine the anode and cathodecurrent structure and the time dependent

Pyrochemical reprocessing refers tohigh temperature chemical processing ofthe spent fuel for separating the valuablefuel constituents, U and Pu, from the fissionproducts for recycling. Molten saltelectrorefining, an important pyrochemicalreprocessing method ideally suited formetallic fuels, exploits the differences inthe thermodynamic stabilities of thechlorides of fuel materials and fissionproducts for achieving the separation. Inthis process, carried out at 773 K., thespent metallic fuel is immersed in a moltenchloride electrolyte and U and Pu areselectively electrotransported to cathodeswhereas the noble fission products are leftat the anode and the rare earth fissionproducts are transferred to the electrolyte.A solid cathode is used for theelectrotransport of Uranium alone whichis useful for processing the blanket and aliquid cadmium cathode forelectrotransporting U and Pu togetherwhich is employed for processing thedriver fuel containing higher amounts ofPu.The selective deposition of U on a solidcathode is enabled by the higher Gibbsenergy of formation of its chloride thanthose of the chlorides of Pu and minoractinides. At the liquid cadmium cathode,however, the codeposition is facilitated bythe lower activity coefficient of Pu incadmium compared to that of U.

The advantage of this process is thatit uses molten salt as electrolyte that ismore compatible with highly radioactiveshort cooled FBR spent fuels than theorganic solvents (tri-butyl phosphate)used in PUREX process that wouldundergo radiolytic degradation. The criticalmass of fissile material in the salt is lessrestrictive compared to that in aqueous

Suddhasattwa Ghosh(DOB- 30.09.1980) did his

M.Sc(Chemistry) from Rani DurgavatiVishwavidyalaya, Jabalpur, MadhyaPradesh in 2003. He is from the 47th

Batch of BARC Training school andjoined IGCAR in September 2004 as

Scientific Officer (SO/C).

Forum for Young Officers

1919191919

operation with 16 possible cases has beencompleted using MATLAB. Thecomputations involve setting up ofsimultaneous algebraic non linear equationsand systems of linear equations of sparsematrices that are solved using standardtechniques available in the literature. Ourcomputations show that the rates at whichU and Pu migrate to the LCC depend ontheir respective saturation levels at theLCA and LCC. For example, the followingplot represents the conditions when boththe electrodes are unsaturated with bothU and Pu to start with and then cathodegets saturated with U after a certainpercentage of electrotransport.

When both the electrodes areunsaturated, the rates of transport of Uand Pu are equal as well as the Pu/U ratiosat both the electrodes. After about 55 %transfer Cd cathode gets saturated with U.The rate of transport for U increases, as aresult of which the Pu/U ratio at the cathodedecreases and that at the anode increases.The effect of the electromotive force at

The diffusion theory model

The model based on diffusion layertheory is a better tool for predicting thebehaviour of the electrorefining processthan the thermodynamic model. This isbecause the latter does not incorporate thevarious electrokinetic factors that mightaffect the overall electrorefiner operation.It takes into account the diffusion,electromigration, Stern Geary equation andButler Volmer kinetics at the electrodeinterfaces. It will involve setting up ofcoupled nonlinear partial differentialequations that would be converted to asystem of ordinary differential equations.Hence the model can be applied to studythe effect of various physical parameterson the performance of the electrochemicalprocess such as diffusion layer thickness,electrode geometry, diffusion current andthe applied composition. It has beenshown that the polarization curvesgenerated using these models are inagreement with the experimental results.The development of codes based on thediffusion model has been initiated in ourlaboratory.

A laboratory scale argon atmospherefacility in our laboratory is used to carryout studies on the molten saltelectrorefining process on U alloys andnow, a demonstration facility forengineering scale process studies is beingset up. The results of the computationswould be used for optimizing the designparameters of the electrorefining cell andthey will be validated with the experimentalresults.

(Suddhasattwa Ghosh and ColleaguesFuel Chemistry Division,

Chemistry Group)

the anode and cathode has also beenstudied as a function of electrotransport.The simulation studies would need to bevalidated by experiments that would becarried out at high temperature involvinghandling of active materials in argonatmosphere glove boxes.

The present model will be extendedto three-component systems with whichthe transport behaviour of the threecomponents of U-Pu-Zr alloy fuels duringelectrorefining can be studied. Irradiationof test fuel pins with metallic fuels andtheir reprocessing will form part ofdevelopment programme for metallic fuels.The plutonium concentration of the U-Pu-Zr fuel for the test fuel pins in FBTR willbe as high as 50 wt.% and there is noinformation in literature on the behaviourof such high Pu fuels. Our modelling willbe used for predicting the behaviour ofthese test fuels during reprocessing whichwill be verified during the actual processingof these pins.

“…The emphasis throughout has been on developing know-how indigenouslyand on growing people, able to tackle the tasks, which lie ahead…”

- Homi. J. Bhabha

2020202020

Structural Integrity ofCore Catcher under CoreDisruptive Accident Loading

The core catcher is basicallydesigned for accommodating the coredebris resulting from melting of 7 fuelsubassemblies in order to meet the safetycriteria. However its structural integrity isinvestigated for accommodating wholecore meltdown condition. The core catcherdesigned for PFBR consists of a 20 mmthick core catcher plate (CCP), with a flatpan of 6.4 m diameter. A heat shield plate(HSP) is provided to protect the CCPagainst thermal shocks. Support pins areprovided between HSP and CCP tomaintain the gap. At the centre, a 500 mmdiameter chimney is provided to aidnatural convection flow of sodium. Thewhole assembly is placed over a numberof tapered ribs, which are welded to thecore catcher support plate.

In the event of a core disruptiveaccident, a very high pressure will first acton the core catcher, and subsequently themolten core debris will start settling on it.For the structural integrity assessment, a40° symmetric sector (Fig. 2) along withMV and CSS shell is modeled in CAST3M, a computer code issued by CEA,France. The CC is first analysed for the

Shri Bhuwan Chandra Sati(DOB – 30/03/1978) obtainedhis B.E Degree (Mechanical

Engineering) from MJP RohilkhandUniversity, UP in 2001. He joined

IGCAR from the 45th batch of BARCTraining School as Scientific Officer

(SO/C) in September 2002.

In the 500 MWe sodium cooled pooltype fast breeder reactor (PFBR) the entireprimary circuit including core is housedinside the main vessel with a top shield.The grid plate supports the coresubassemblies (CSA), which is in turnsupported by the core support structure(CSS). The CSS is attached with the mainvessel bottom at the triple point through asupport shell. The safety of reactor isensured in many ways by followingdefense-in-depth approach. Accordingly,even though core disruptive accident(CDA) is a very low probability event, itis investigated in detail including itsconsequences. Subsequent to CDA, themethod of post-accident heat removal isalso well planned. In order to mitigate theconsequences of core melt down, the corecatcher structure is placed below CSS,which gets supports from CSS supportshell (Fig. 1). The core catcher must collectthe core debris, support them and maintainin sub-critical configuration. It mustprevent the debris settling on MV and keepthe MV temperature within acceptablelimits from creep consideration byfacilitating sufficient natural convectionmode.

transient pressure loading during CDA.The stresses for the reference geometry(Fig. 3a) are found to be high at the supportflange to CSS shell junction and supportplate knuckle to flange junction. Thestresses and deformation on the HSP arealso found to be high. To reduce thestresses, the geometry at the junction hasbeen modified. The flange support ischanged to skirt support. The support pinsbetween CCP and HSP are shifted radiallyoutward. Analysis has been carried outwith modified geometry (Fig. 3b). Thestresses (Fig. 4) for this case were found

Fig. 1 Schematic of core catcher Fig. 2 FEM mesh for the analysis

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Fig. 3 Recommended geometrical shape of core catcher

Fig. 5 Effective Temperature Vs Allowable TimeFig. 4 Von–Mises stresses on CC junction for modified geometry

debris of the whole core at hightemperature. Based on the apportionedcreep damage of 0.4 for category 4 events,the variation of effective temperature atwhich CC can be subjected to, is plottedagainst allowable time (Fig. 5). Based onthe apportioned creep damage of 0.4 for

to be within the limits of RCC MR 2002,recommended design code for PFBR.

Subsequently, the structural integritywas assessed for post-accident heatremoval phase with respect to creepdamage for the steady load of molten

category 4 events, the allowable time at1173 K is 308 days, which is well withinthe acceptable limit.

(Bhuwan Chandra Sati and Colleagues,Mechanics & Hydraulics Division,

Reactor Engineering Group)

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Techniques” commenced with two invitedtalks; the first by Dr. Jagdish Arora, ChiefLibrarian, IIT, Delhi on “ KnowledgeSharing Tools & Techniques” wherein heunderlined the importance of variousstages such as Data to Information toKnowledge to Wisdom. The sixth sessionwas on “Library the Gateway”. In this, ShriM. Somasekharan, Head, SIRD spoke on“Patrons Technology & the Library”. Heemphasized the importance oftechnological updates, Digital Library forlibrary patrons, evolution of library andthe role played by technology and thepatrons in this, benefits steps / philosophybehind Digital Library and Model Library– IGCAR.

In the valedictory function, at the endof two day conference, Shri M. Rajan,Director, Safety Group, IGCAR welcomedthe participants. The Presidential addresswas given by Dr. Baldev Raj, Director,IGCAR and Dr. G. Amarendra, IGCAR,presented the conference summary. Thevaledictory note was given by Prof. S.Narayanan, Dean, Academic Research,IIT, Madras. Shri M. Somasekharan, Head,SIRD, IGCAR proposed the vote ofthanks.

The conference in all was veryenriching, informative and covered avariety of topics in current trends ininformation technology. It broughttogether the best brains in the country foraddressing the latest trends in librarysciences viz. the era of digital libraries.

(M. Somasekharan, SIRD)

HIGHLIGHTS OF THE CONFERENCE ON

Recent Advances in Information TechnologyREADIT-2005IGCAR, July 14-15, 2005

delivered a lucid presentation on e-learning. Shri M. Somasekharan, Head,SIRD, IGCAR proposed the vote ofthanks.

The conference encompassed sixtechnical sessions including invited andoral presentations. The themes for thesesessions were “Facets of Digital Library”,Information Management”, KnowledgeManagement”, “Knowledge SharingTechniques” and “Library the Gate Way”.The technical session on “Facets of DigitalLibrary” commenced with an infectiousand enthusiastic invited talk by Dr. S.Venkadesan, Librarian, JRD Tata Library,IISC, Bangalore, elucidating various facetsof digital library in terms of its contents,organisation, services, technology andpeople.

The topic of the second session was“Information Management”. Dr. Nargund,BARC, Mysore presented a veryinformative talk on “Web Resources forChemical Safety Information”

The third session comprised ofcommercial presentations by WileyInterscience, Libsys Corporation, AccessSciences, IOP and Springer-Verlag.

The fourth session held on theforenoon of 15th July was on “KnowledgeManagement” wherein Shri P.C. Baruaenlightened the participants on theimportance of “Human / IntellectualCapital / resources” and how digital libraryshould pave way for its betterment. Thefifth session on “Knowledge Sharing

Scientific Information ResourcesDivision (SIRD), IGCAR and MadrasLibrary Association – Kalpakkam Chapter(MALA-KC) have been conducting, forabout a decade, a series of conferences on“REcent ADvances in InformationTechnology (READIT)” and theconference for 2005 was held at IGCARduring July 14-15, 2005. The main themeof the conference was “Digital Librariesto Knowledge systems”, with sub-topicson Facets of Digital Library, InformationManagement, Knowledge Management,Knowledge Sharing Techniques andLibrary the Gateway. The conference waspreceded by a one-day tutorial on“Advanced Methods & Technologies forContent Management” and “Applicationof Open Source Solutions for DigitalLibraries” on July 13, 2005.

At the inaugural session on 14th July,Shri P. Swaminathan, Director, Electronics& Instrumentation Group, IGCARwelcomed the gathering. Dr. Baldev Raj,Director, IGCAR gave the presidentialaddress and illustrated the origins oflibrary services and its evolution in thecentre paying rich tributes to thepioneering work of Dr. G. Venkataramanin this regard. He stressed the need for“sharing and synergism of knowledge withproper coherence”. The inaugural addresswas delivered by Dr. T. Ramasami,Director, CLRI, who emphasised theimportance of digital libraries andknowledge updating. The Keynote addresswas given by Prof. S. P. Thyagarajan, Vice-Chancellor, University of Madras, who

2323232323

This year Medimeet 2005 was

conducted on 29th and 30th April 2005 at

the SRI Convention Centre at

Anupuram. This was the seventh in a

series of medical seminars conducted by

the medical fraternity of DAE hospitals

all over India. The tradition evolved

with the first Medimeet held at BARC,

Mumbai in 1993. Medimeets are unique

in that they involve interaction between

specialists of all fields. Unlike the

current trend of conferences for doctors

belonging to a single specialty,

Medimeet brings together doctors from

various fields and from our sister

concerns all over India.

To cater to this medical medley the

lectures for the conference were

carefully chosen to appeal to one and

all. Eminent professors of international

repute consented to grace the occasion.

The conference was inaugurated by

Director, Dr. Baldev Raj whose wisdom

and guidance kept up the zest and zeal

of the organizers throughout the

conference. Shri Prabhat Kumar, Project

Director, BHAVINI, Shri S. Basu,

Director, BARCF, Mr. S.

Krishnamurthy, Station Director, MAPS

and Mr. P. Swaminathan, Chairman,

HMC also graced the occasion with

their presence, support and good will.

The conference began with a guest

lecture by Dr. P.T.V. Nair, Head, Medical

MEDIMEET & PARAMEDICS MEET 2005

DAE Units, each offering a veritable

feast to the audience. There were about

80 delegates in all and the deliberations

of the conference provoked much

discussion and interaction between the

doctors.

Following the above meet, a

Paramedics Meet for the staff of DAE

hospital was conducted at SRI

Convention Centre, Anupuram on 23rd

July 2005. Shri P. Swaminathan,

Director, EIG, IGCAR and Chairman,

Hospital Management Committee

inaugurated the programme. Nursing

supervisors, nurses, nursing assistants,

lab technologists, pharmacists,

radiographers and ambulance attendants

presented papers on the occasion.

Guest lectures by Shri Ilavarasan,

Professor of Pharmacology, Dr.C.L.

Baid Metha College of Pharmacy

Chennai, on Diabetes and

Hypertension; Smt.Uma Mageswari,

Nursing Supervisor, Sri Ramachandra

Medical College on Hospital Infection

Control; Shri P.Subramanian, Sanitary

Supervisor, GSO, Kalpakkam on

Environmental Sanitation were the

other highlights of the meet that

concluded with a vote of thanks by

Smt.M. Lakshmikanthamma, Assistant

Matron, DAE Hospital.

(Dr. A. Vijaya, DAE Hospital)

n

Division, BARC, Mumbai, who spoke on

risk factors in heart disease. Following

this illuminating talk was an allied one by

Dr. Thanikachalam, Head of the

Department of Cardiology, SRMC, and the

recipient of Dr. B.C. Roy award 2004,

that gave an all pervasive insight on

unstable angina and its management. One

of the highlights of the day was the lecture

by Dr. Usha Sriram, endocrinologist par

excellence, who gave new meaning to the

term menopause with her academic

extravaganza.

Dr. Hariharan, Head of Department

of Endocrinology, KMC, Chennai also took

the participants to new realms of modern

medicine in the management of diabetes

mellitus.

On the second day, Dr. Jayanthini,

eminent professor of Psychiatry spoke

on the common but commonly ignored

problem of stress in women. Dr. J.

Balavenkatasubramaniam stalwart

anesthesiologist from Coimbatore gave a

much needed overview of management of

trauma victims.

Dr. J.S. Rajkumar, a well known

gastroernterologist from Chennai spoke on

Abdominal pain. This was followed by

another very relevant talk on consumer

protection law with reference to doctors,

by Dr. Cheran, Professor, Stanley Medical

College, Chennai. There were also several

presentations by the doctors of various

2424242424

5th Quality Circle Awareness Day-2005Quality Circle (QC) Awareness Day programme is being conducted every year at IGCAR in order to propagate

the message about the benefits that will accrue among the work force and also for the orgainisation. This year,with the formation of Apex committee for Quality Circles and introduction of Quality circles by more groups, theawareness day programme was conducted for two days on 6th and 8th September 2005. Because of therelevance of QC for every one, various professional bodies in Kalpakkam participated in arranging the programme.The programme was inaugurated by Dr. Baldev Raj, Director, IGCAR & GSO. Shri M.R.Ranganathan, Head,Marketing of SRM Technologies, Chennai delivered the keynote address on “Institutional support and motivationfor growth of QC movement”. Thirteen Quality Circles from IGCAR, schools, hospital and GSO presented the casestudies. In addition to the participants, members of the newly formed QCs and personnel from other groupsnumbering around 200 attended the programme. Professional judges from Chennai assessed the case studiespresented and also gave valuable guidance to the QC members and motivated them. The enthusiasm shown byall the participants were very gratifying and this helped personnel from other divisions come forward to formQCs.

(K. Ravishankar and V. Venugopal)Organising committee- QCAD-2005

Awards & HonoursDr. Baldev Raj has been awarded the prestigious Indian Nuclear

Soceity (INS) Award for the year 2004. He has been electedPresident of Indian Institute of Metals. He has also been elected

fellow of The Indian National Science Academy (INSA), New Delhi.He has been conferred with a honorary doctorate by Sathyabama University,Chennai for his contributions in the field of Science & Technology of Fast Reactors.

Dr. U. Kamachi Mudali, Corrosion Science & Technology Division (CSTD) wasawarded the INS Medal for the year 2004. He has been awarded the prestigiousMetallurgist of the year award for 2005 by Ministry of Steels & Mines. He has alsobeen awarded the Homi Bhabha Science & Technology Award for the year 2004.

Dr. K.G.M. Nair, Materials Science Division (MSD) has been selected for theMaterials Research Soceity of India (MRSI) Medal Lecture for the year 2006.

Dr. A.K. Arora, MSD has been awarded the Prof. Y.T. Thathachari MemorialResearch Award, Mysore for the year 2005 in the area of physical sciences.

Dr P.R.Vasudeva Rao Chairman, Editorial CommitteeMembers: Dr.G.Amarendra, Shri M.Ganapathy, Dr.K.V.G.Kutty, Dr.Mary Mohankumar, Shri G.Padma Kumar, Dr. B.Purniah,

Shri Shekar Kumar, Shri M.Somasekharan, Shri R.Srinivasan, Shri R.V. Subba Rao, Shri K.V.Suresh Kumar.Published by Scientific Information Resources Division, IGCAR, Kalpakkam - 603 102