BHABHA ATOMIC RESEARCH CENTRE

,. ',p"imenta] ,et.pp to me.,Ple "ltioal ,,"entof,"peloondpc"n, wlm,.

2. Splph" He,aflporide (SF) Reactol.

3. Prototype of electrolyse, plant (front ~ew)

4. VI,ion 'y"em fol flact"e "peliments.

-'"Government of India

BHABHA ATOMIC RESEARCH CENTRE

BARC Founder's Day Special Issue

October 2000Issue No. 201

Homi JehangirBhabha (1909-1966)

7/ :Jribu/e /0 //ie 90under &

7/rchi/ec/ of gncha 's 7//omic

0nery-y :JJroyramme

Homi J.Bhabha was born to Jehangir H.BhabhaandMeherenon October30, 1909.He studied at the Cathedral and JohnConnon High School, the Elphinstone

Collegeand theRoyal Institute of Sciencein Mumbai. He was brilliant instudiesandwon manyprizes. At theageofeighteen,his parentssenthim toCambridge,where he passed the Mechanical Science Tripos and theMathematicsTripos, both in first class. After pursuing researchfor afewyearsunder theguidanceof eminentscientistslike Neils Bohr,Rutherford,WolfangPauli and Enrico Fermi, Bhabhareturned to India. He becameaSpecialReaderin TheoreticalPhysicsat the Indian Institute of Science,Bangalore.

On the recommendationof the Nobel laureateDr C.V. Raman, he waselectedas a Fellow of the Royal Society (FRS) in 1941. Many honoursfollowed and he was conferredthe degreeof Doctor of Scienceby manyIndian andforeign universities.

In 1945, BhabhafoundedtheTataInstitute ofFundamentalResearch(TIFR)in Mumbai with a grant from Sir Dorab Tata Trust. Later on August 10,1948, the Atomic Energy Commissionwasset up by the GovernmentofIndia with Bhabhaas its Chairman. In 1954, the Departmentof AtomicEnergy (DAE) wascreatedto developfacilities neededfor theatomicenergyprogramme.

With the full backing of the then Prime Minister Jawaharlal Nehru, Bhabhastarted building the nuclear energy establishment, and various buildingsand facilities started coming up at Atomic Energy Establishment, Trombay(AEET). Soon the research reactors Apsara, Zerlina and CIRUS were

inaugurated. On January 12, 1967, AEET was re-named as Bhabha AtomicResearch Centre in memory of Homi Bhabha.

The seed sown by Bhabha for the atomic energy programme has grown and

developed into a gigantic tree, comprising nuclear power stations, heavywater plants, radiopharmaceutical laboratories, etc., spread all over India, tocater to the diverse needs of the country in the areas of power production,agriculture, medicine and industry.

In the beginning of this new millennium, the Department of Atomic Energyaspires to fulfil the dream of the Indian masses to become self-reliantandself-sufficient in power production, and to provide supporting facilities inthe agriculture and health sectors.

On this day, the birth anniversary of Homi Bhabha, the staff of BhabhaAtomic Research Centre and other units of DAE, remember with gratitude

the founder of this great establishment. The nation owes a great debt to

Bhabha for leading its people into an era of modern technology and makingthe nation at par with the developed nations in the field of nuclear energydevelopment.

Bhabha's birthday is observed as the Founder's Day in BARC every year.

This special issue of BARC Newsletter is being brought out on this occasionas a homage to this distinguished Son of India.

This volume could not have been brought out in time without the cooperativeefforts of Mr T.e. Balan and Mr PAS. Warriyar of Library & InformationServices Division, BARe.

~--(Dr Vijai Kumar)

Head, Library & Information Services DivisionBhabhaAtomic Research Centre

BARC NEWSLETTER October 2000, No. 201

(Founder's Day Special Issue)

CONTENTS..........................................................................................................

CHIEF EDITOR

O,V;j,i Kum"

Towards ulrimate controlof atomic and molecular

processes by lasers 1B.N. JagatapHorni Bhabha Science & TechnologyAward for the year 1998

Biomedical applications oflasers 13P.K. GuptaHorni Bhabha Science & TechnologyAward for the year 1998

Scaling of the steady stare andstability behaviour ofsingle-phase natural circulationsystems 27P.K. VijayanBARC Technical Excellence Award forthe year 1998

Bioreactor technology forlarge scale cultivation ofplant cell suspension culturesand production ofbioactivecompounds 41D.P. FulzeleBARC Technical Excellence Award forthe year 1998

-;;,;"", t

MANAGING EDITOR

T.e. B,I,"

COMPUTER GRAPHICS & LAVOUT

P.A.S.Wm;y"

Gas detectOrs for heavy ionexperimental nudear physicsresearch ~ " 47D. C. Eiswas and R.K. Choudhury"S.N. Seshadri Memorial InstrumentationAward", 1997

Simulation and experimentalverificarion of hyper fine spectrumofU-233 57

EN Jagatap et al.Best Paper Award in the AnnualConference of Indian Nuclear Society(INSAC-2000), 2000

Electron beam welding ofcopper to AISI-304SS 63TK. Saha et al.KCP Award 2000 at the International

Welding Conference -IWC'99, 1999

Phosphorus determination byderivative neutron activation

analysis 72Y.M Scindia et alBest Paper Award at the 1/1'NationalConference of Indian Council ofChemists, 1999

Determination of H, content inzircaloy using hot vacuumextraction -quadrupole massspectrometry (HVE-QMS) 78Y.s. Sayi et al.Best Paper Award at the SeventhNational Symposium on MassSpectrometry, 1996

Uptake of metal ions byextraction chromatOgraphyusing DMDBTDMA as rhestationary phase 81S. Sriram et alBest Paper Award at Nuclear &Radiochemistry Symposium, 1999

Preparation and thermal studies on

Pu(MoO), and Na'pO (MoO), ... 85N.D. Dahale et alSecond Best Paper Award at theTHERMANS 2000 Symposium

A study of solid state reactionbetWeen strontium carbonate andrutbenium dioxide 89R.K. Mishra et .1.Second Best Paper Award at theTHERMANS-2000 Symposium

Mass spectral studies for thedetermination and speciation ofarsenic by Gas Chromatography-Mass Spectrometry (GC-MS) 95S.K. Aggarwal et.1.Second Best Paper Prize In ISMASSymposium on Mass Spectrometry, 1999

Isotope ratio measurements forplutonium in isotopic referencematerials by Thermal IonisationMass Spectrometry (TIMS) usingtotal evaporation technique 98SK. Aggarwal et al.Second Best Paper Prize In ISMASSymposium on MassSpectrometry, 1999

Vacuum decomposition patternof ferrous ammonium sulphate-a quadrupole mass speCtrometricstudy 103Y. Sesha Sayi et aI.Second Best Paper Prize In ISMASSymposium on Mass Spectrometry, 1999

X-ray and thermal studies on

TI-Pu-Mo-O system 106N.D. Dahale et .1.

Third Best Paper Award at the NationalSymposium and Conference on SolidState Chemistry and Allied Areas(ISCAS 99), 1999

Normalized dZ/dT waveform

for easy assessment of periphetalblood flow 108

Jagruli Chheda et .1.Consolation (UG) Prize in.1he Symposiumon Biomedical Engineering andNuclear Medicine (SBME-NM2000)

TOWARDS ULTIMATE CONTROL OFATOMIC AND MOLECULAR PROCESSES

BY LASERS

B.N.JagatapLaser & Plasma Technology Division

Bhabha Atomic Research Centre

SPECTROSCOPY HAS SHOWN

am"ing re,ilience and freshness ever since

rhe dcvelopmem of quantum mechanics at

the beginning of the 20th century. In the last

two decades, thanks to the developmem of l"m,

wc havc seen the return of 'peCtrO>copy ro it>

former position of scientific prominence. In

many respem thc 1980s c'cpresemed a period in

which thc 'pcCtrO>COPY with I"m undetwent

the difficult transition from being a purely

academic subject ro a discipline with imponam

technological and comme<cial applications. This

comemporary outlook of spectroscopy form, the

b"is of our work, both experimemal as well a,theorerical.

In rhe recent years, our work in laset> and

'pectroscopy focu;;cs on rhe use of lasm tocontrol and railor aromic and molecular

processes. Thi, work encompasses three

imponam i;;ues in the comemporary physic,.

Fimly, it addrme> the problem of isotope

selective excitation and ionisation, which have'

imponam ramifications in the nuclear fuel cycle,

specifically in rhe thorium urili5Onon programme

of the depanmem [1-9J. The systems we

investigate in this domain ate I"er clean-up of

U-233 and denaturing of zirconium. In the

language of control theory the isotope specific

excitationlioni5Otion using lasm is a "pa;;ive"

comrol since it i, realised by the use of inserinsic

isotope shifts exhibited by the atomie systems. In

our work, we also seek "active" comrol wherein

we devi,e strategies to change the atomic and

molecular response in a fundamemal manner to

control excitation, ionisation and di;;ociarion

[10-15J. This forms the second importam

componem of our work. Involved in this workare the ide" on coherem comrol which are

expected to form the basis of the new generation

of lam ptoce;;ing of marerials. The third

componem of our work is to use laset> to conrrol

the external degree, of freedom such" positionsand velocities of atoms to obtain cooled and

trapped atoms for experiment> on the

foundations of physics [16-21J. The fascinatingaspect of this enrire endevour is that while at the

fundamenrallevel it unravels new and important

aspem of laser-atom and laser-molecule

imeractions, at the applied level it finds an

importance in the configuration and realisation

of laser selective proce;;es for high valuematerials.

Laser Clean-Up of U-233

The Indian nuclear power programme, in the

long term, is based on energy from fi;;ion of U-233. The fi;;ile U-233 is bred from fertile

thorium of whieh our counrry has large

deposites. In Indian nuclear fuel cycle (INFC).

Th-232 will be converted to U-233 in advaneed

I 1 I-

heavy water reactors, lit breedet teactors and in

the futuristk acceletatot dtiven subcriticai

reactors. Ptoduction ofU-233 is accompanied by

the unavoidable fOtmation of small quantities of

U-232. The majot cost of U-233 fuel is in the

requirement of remote handling fot fuel

fabtkation, ttanspottation and fuelling

operation, due to the hard y-emitting daughtet

produCtS of U-232. The economk gains of U-

233 fuel will be boosted if U-232 impurity is

temoved Ot btOught down to permissible level by

employing a laser isotope sepatation (LIS)

process. Such a ptocess is referred to as "U-233

Clean-Up" process in INFC [1,4].

It must be emphasised here that the development

of this process, from physics to technology, has

to be done fot the first time and independendy

in India, since no other countty is as much

depe.ndent on thorium utilisation as India.

Needless to say that the entire development has

to be done withour the benefit of published

literature, data Ot repott. This ptesents a ttuely a

238U

-10 -8 -6 -4 -2

Fig.l. Sp"".a 'fIV-235, V-238) I"'i'"immcal] and IV-232, V-2]3) (,imu/""d] ft" rypicalfim "'p ".amirion.

challenging area of work and also provides the

satisfaction of doing everything fot the first time.

The heart of the clean-up process is selective

resonant three step photOionisation by tunable

lasers. At the physics level, the process amounts

to selective excitation and photoionisation of the

impurity isotope, U-232, and subsequent

removal of the ions by applying electtosratk field

[3-6]. Building of the requisite separation physics

fot the Clean-up process, therefore, requires

firstly a large amount of atOmic data which has

to be generated in house using various

spectroscopic techniques. To ensure high

selectivity and large photoionisation effciency we

need data on iwtope shifrs (IS), hyperfine

structure (HFS) of U-233 due to non-zero

nucleat spin, level lifetimes, absotption and

photoionisation cross-sections etc. Furthermore

to configure a process which minimises isotOpic

scrambling during the collection of ions, one

needs to know various collision ctoss-sections

involving atoms and ions; the information of

which is also provided by spectroscopy.

0,003

232U

0.002£.c.E0.001. 233U

0,000

-8

I 2 r-

Our effo", have been (0 genmte this crucial

data base using a "riety of theoretical and

experimental techniques [6-8J. Our theorericalwork resulted in ,ti"e first ever data base for (V-

232, V-233) system. An example of these efforts

we shDw in Fig. I simulated spectra of (V-235,

V-23S) and (V-232, V-233) systems for a typical

first step-reamition. Note here rhat the V-233

h", a broad hyperfine strucrure and that the odd-

even staggering of V-233 remlrs in a small

isotope shift (V-232, V-233). It is also clear from

Fig.! that the separation task in the clean-up

process is a demanding one, since overlapping of

spectra of V-232 and V-233 will be more as a

rule than an exception. Somewhat berter

situation is presented in Fig.2, which shows

simulated spectrum for another first step

transition exhibiting an adequatc spectral

separation. An cxremive simulation work has

helped us to identifY the transition sequences

such", this (cf. Fig.2) which form the

foundations of the Clean-up pm"ss.

0.003

i:i 0.002

.~0E 0.001

0.000

-4 -3

Fig.2.233,

"amhi,n 'f U-232 and U-

On the experimental side, conventional high

resolution spectroscopic techniques together with

l",er spectroscopic techniques involving one or

several lasers, operating under pulsed and

continuous modes, have ro be implemented for

generating this data b",e for the clean-up process

[7,SJ. High resolution spectroscopy of

radioactive isotopes requires quite a different

approach from the conventional spectroscopy.

Only a few experiments would be possible with

radiaoactive elements and to get the same

amount of reliable data, new techniques have (0

be devised. New high resolution spectroscopic

sources developed during the course of our work

are shown in Fig. 3.

Sp""""pi, wurc" dane/'p,dJ" high'n 'P""""PY ""fed" th, ruan-up

p"g"mm,. Thcscwurc" w"k with milli "mi"'pam quantiti"'f iw"p" 'f int""'. T,p'H,lhw cath,d, di"h"g' wurc" fa' ,missi"

andIdm 'P"""""- B,"'m..A"mi,wurc, fa' ""Iuti" flu"""n"

'P""""Py.

These sources work with milligram to microgram

quantities of samples thereby avoiding the

I 3 I-

pcoble= connected wirh radiaoaCtive nature

(eg. U-232) of imerest. In Fig.4. we show high

resolution spectrum ofU-238. U-235 and U-233

cecorded on a recording Fabry Perot Optical

Spectrometer. Capabiliry such as this has been

achieved rhrough innovative approaches backed

by rhe expertise developed over rhe years. This

work has also thrown newer possibilities on high

cesolution spewoscopy of higher actinides and

highly radioactive materials. The confidence 'in

our approach is provided by close matching of

the simulated and c:xperimemal atomic data; an

example of which is presemed explicitely in OUt

award winning paper (7J included in thisvolume.

The spemoseopie data provides only the initialconditions for laser-acom imeractions. The

selectivity and Stripping efficiency ate determined

by the kinetics of laser-atom imeractions [5.6].

High selectivity is required in rhe clean-up

process on tWO accountS; fi"tly to minimise the

loss of the fissile isotope and secondly to

minimise the photOn cost. High accessibility is

of rhe sample or the rarity of rhe isotopes

important for recovery of rhe LIS process and

thereby minimising the number of stages

required to obtained desired purity of the

processed material. We have done detailed

invesrigations of photoioni"tion physics to

obtain rhe regions of operating parametetS such

as laser and vapout characteristics. Various issues

studied hee< ate second step seleCtivity.

Boltzmann inaccessibility. spectral accessibility.Ctitetion for selection of transitions etc. These

resultS give rhe first cut analysis of the physics of

the sepat..tion task involved in rhe clean-up

process. In Fig. 5. we show the results of one

such study. where rhe selectivity and accessibility

is investigated as a funCtion of laser bandwidrh

and axial temperature of the vapour. The

operating conditions of the process are decided

by the trade off between selectivity and

accessibility. Our work on the selectivity physics

provides guidelines. clarifies issues related ro

selectivity. rhroughput and recovery in rhe

U-233 clean-up process.

Fig.!. High molution 'p""um of 5915 AO"""ition in u"nium ;"'op" "",rkd in que lab"",ry.Exp"imtn" w,h '" th;, p",irk dato ,n i""p' ,hi!" and hyp'ifin, ',,""um "qui"d fi' th, <kon-upp"!7amm,.

I 4 I-

" ,h,Ima..,J,b, ,u,n-,p pm"".

Anothec example of our wack on "passive"

control is "denaturing" of zirconium which is

intimately connected with INFC [9J. The

thermal teactots utilising thoeium fuel cycle use

comidetable tonnage of zirconium in the fixed

in-coee components as well as in the fuel

cladding. Zicconium has five isotopes and the

neurmn absorption cmss-section of 0.186 b is

mainly contribured by Zt-91 which has anabundance of I ] .2%. If the concenccation of this

isotope in zicconium is reduced to 3%. the

absorption cmsHecdon will reduce to 0.088 b.Use of such "denatuted" zirconium fur the

pcessuce tubes, "landtia and cladding would

allow greater design flexibility and extended fuel

cycles foe nuclea; teacto", both AHWR.; " wellas PHWRs.

Since the denaturing of zirconium involves

removal of the middle isotope, the proposed

method is LIS in aromic vapour. This method is

pacciculacly attractive in view of the development

of LIS process foe U-233 cbn-up. Of course

new spemoscopic and innovative phoeo-

ionisation "hemes need ro be adapted. This need

stems hom the fact that the isotope shifts in the

spectcum of zirconium is in the range of 100-200

MHz. This, along with the broad hypecfine

mucture ofZt-91 (nuclear spin 1=5/2),cesults in

the oveclap of the spemum of Zt-91 with the

spema of the even isotop", The absence of

spemal separation, thecefoce, makes selective

photoionisation of Zt-91 difficult. It is, howevec,

possible ro inttoduce isoropic selectivity by

invoking altemate photoionisation physics

namely, "leetive phoroioni"tion by lasec

polatisation induced population trapping. We

have developed extensive simulation procedures

which can be used fur identifYing the optimal

ccamition "quences and Ia"t polarisatio", foe

selective photoionisation of Zt-91. Our work

points out to the special featuces of this

separation t"k and provides the cequiced physics

base foe the process of denaturing of zicconium.

Coherent Control

Molecular Processes

of &Atomic

LIS is based on the concept of "passive" control

since the isotope selectivity in photoionisation is

achieved due to inminsic atomic ptopmies such

as i'"tope shifts. When the phoeoceacdng sYStem

is enecgetically degeneme, conttolling the

outcome of the atomic/molecular process

cequites a mote fundamental approKh. One

such approach is "cohecent control" which is

based on the intetfecence between optical

transitions. This phenomenon ati"s when

atomic/molecular system is driven cohetencly

thmugh two competing path-ways which exhibit

intecfeecnec analogous to a double slit

cxpniment in opti". This intederence in tom

can be controlled by pacametecs of the dtiving

fields enabling cantco! of exciradon, ionisation

and dissociation of atomic/molecular sYStems.

This methodology pcovides intereSting soluriom

in many arw of chemical physics ranging fcom

J 5 \-

is

><E-<:::5~-<~0~p...

0.10

0.12 / ......\ p-

\

\

\'

"\

\

\

\\

0.08

0.06

2.0

Fig. ~ Cah",nt mntml al tb, papulatiam in th, hyb,id <tat" Iff.. Tap' Om- "' twa- ph"an mitati,. mmp"iti,. "t up

"ing 1&" al fr'qum'Y tO2 and it; "mnd ha~,.i, to Ba"am, Th, papulatiam al tb, hybrid <taw P. '" a /Un"i,. al

th, "latiatph"" 0= °1 - 2°2 alth, twa puhd I&m ~citing n-} ta n-2 "amitian afth, hydmgm .tam. F,,4tai"

",Riff}l}.

I 6 I-

lasers without population invwion to contwl of

chemical ,eac,ions [IOJ.

An interesting example of the cohe,ent conttol is

provided by om theoretical wo,k on the

pwduction of dipolar hydrogen atom 2s-2p

",onance hyb,id, '¥" =CI2s):l:12p))/J'i,

through the use of competitive one- and tWo-

photon transitions fwm the gwund state [Ill.

Note hm thar the hyb,id stares are ene,getically

nea, degen"'te and a usual excitation processwill be nonselective in the sense that it will

populare both these states equally. By pwviding

tWo competing paths, we can contwl the

excitation to a specific hyb,id state. In Fig. 6, weshow this contwl scenario as a function of the

phase diffmnce betWeen the lasw inducing the

one- and tWo- photon transitions. Here. complete

contwl ove, the pwduction of specific hyb,id

state is achieved by changing ,elarive phase oftWo monochwmatic lase, beams which alters the

degtee of demuctive intde,ence betWeen tWo

paths of excitation. This aspect of controlling

ttansitions without changing the radiation

intensity is interesting from both basic and

applied point of view. In molecula, systems, wehave shown ,hat similar control can be

established by competition betWeen tWo-photon

optical excitation parhways [12].

To study mch intticate contwl phenomenon, we

require the stare of the at[ theotetical models and

experiments. am investigations on spectroscopy

and dynamics of femtosecond, tWo colour,

pump-probe experiments involving simultaneous

and sequential tWo-photon excitation illumate

how theoty and experiments go hand in hand

[13]. One of the consequences of om theoty is to

ptedict cos40 dependence of the excited state

fluotescence for a-NPO molecule in

contradistinction to cos20 dependence in azulene

:~90 180 270 360

relative polarIzatIon angle e

molecule. He,e 0 is the angle betWeen the

polarisation vectors of pump and ptobe lasw.

Further, this dependence can be contwlled by

contwlling the laser intensities. These theoretical

predictions were verified in totality in a series of

J 7 I-

conttolled expeeiment,. In Fig.?, we ,how these

cxpecimental and theo"tical "sui". Thi, work is

of imporrance aho in the m"wrement of dipolemoments of molecular s"tes and femro"cond

actinomeery.

Development of very sophi"icated theomical

methods is a prNequisite for much of the

contempo"ry spectroKopic teswch. An

example of this i, our theomical wack in the areaof intcnse field I",,-arom inte"ctions [14,15].

The rapid developments in the la"r technology

have now made it possible to rdise very high

intensity (>1012 Wlcm2) ult" shorr pulsed laser

wmces. Such unpreccdented intensiri" are at the

origin of a considerable intece" in studying the

t"ponse of an atom m a molecule ro intemelaser fields which include above threshold

ionization, high harmonic gene"tion, multiple

ionization and ",bilization in aromic systems.

Inteme field laser-arom interaction is inherendy

non-perrmbative ,inee the atom expeeience a

lase. elemic field which is comparable ro mmore than the Coulomb field of the aromic

elemon. Undemanding of the nonlinw

mpome of atom to ,ueh fields, therefote,

requir" an explicit non-perturbative time-

dependent approach. What we look here is the

"direct" sol urian of the cime dependent

Shrodingee equation with timc dependent

sinnsoidal potential; a daunting task even for a

simple" aromic system wch " one clwron arom

and a challenging pmblem in compurational

physics.

We have developed a mcrhodology based on split

operaror fa" Foucier "ansfOrm (SOFFT)

technique and implimented it sucessfully on

Anupam parallel computing machine, which can

be u"d conveniendy for "udying inten" field

phenomena in hydrogen-like aroms and diaromicmolecule>. Such theoretical studies serve" a

di,'ect test fm compacison between experiments

and rheory. In Fig.S we show the probabiliry of

ioni>ation of hydrogen atom by a 10 fs puhe of

1012 Wlcm2 intensiry. Such calculations are

possible to be done only in a few labomories in

the wodd. We have u"d this computacional

scheme to "udy the problem, of pha"

dependent excitation, ionizarion and harmonic

genmtion. Th"e provide many intersting

control phenomenon hetherto unknown in low

intensity regime.

1.00

0.95

pg

0.90

0.85-1000 -500 500 1000

Time (atomic Units)

Laser Cooling of Atoms

So far we have seen the role of lasee in

controlling the intemal degrees of freedom. Laser

cooling is an area which looks to conttol and

manipulare the extemal deg"es of freedom, the

posicions and velocities, of atoms using

electromagnetic fields [16-18]. L"t two decades

have seen an enotmous progre" in development

of techniques to cool and trap neutral atom, and

ions. These techniques have made it po"ible to

J 8 I-

",ch emirdy new regime, of low tempe"'me

mch a; nano kelvin and co perform uhra high

p"cision experimems co test the elcmentary law,

of natme. The technique; of laser cooling and

te'pping have matured to a poim dBt they are

finding 'ppli"tions in orher "'" of science, eg.

high "solution ;pectroscopy, mermlogy,

nonlinear optie;, collision phy;ie;, condemed

matecr phy;ics etc. Acomic cooling techniqucs

have been med co cool dilute albli vopours to

sub-micm kelvin tcmpmtures co "hieve Bo;e-

Einstein condem"ion; a phenomenon which

had eluded physicim for over seventy y'"'s. Very

recemly, the atom loser, coheeent beam of

massive bosom, h" become, reality [18].

Indi, h" remained isobted fmm all these

excitemems foc , long time. BARC has "ken up

lead in thi, field ,nd planned an extemive

pmg"mme on laser cooling and t"pping of

acoms and ions in the IX FYP. Thi, pmgr'mme

aims at serring up , facility foc b"r cooling ,nd

te'pping of atoms and perform, v"iery of

expeeiment> at the foundations of physics. We

are developing tliis prognmme with 10,,1

experri" ,nd local technology. In rliat regard

BARC, with it's inhcr'em multidisciplinary

character, is an ide,l pbce where mch ,n "riviry

can flomi;h. In the IX FYP, the objectives of the

programme are two fold; ultra-high re;olurion

spectroscopy foc fundamcn,,1 phY'ics

"peeimcnts and expeeimems leading ro Bose-

Einsrein condensation. We expcct co get

involved, in due course, io atom optics whichrefers to , fresh oudook in which acomic be,m,

are thought of ,nd m'nipulated like photons in

light b"m; ond , collection of techniqoes for

doing mch manipulations.

Developmem ofl"ee cooling techniques, namely

votious type; of tnps, is cemnl co ,II these

pmgnmmes. One of the most efficiem reaps for

neuteal atoms is the magneto-optical reap

(MOT) which is based on the scanering force in

an inhomogenous m'gnetic field [16J. MOT

pmvides an eleg,nt way of obtaining large

sample of cold and trapped acoms. It has a

compmtively largc reap depth and is cap,ble of

achieving densitie; " high" 1012 acoms/cc at a

tempe"'mc down co a few micm Kelvin. We

h,ve sucee;shdly developed ,nd installed, MOT

in BARC for cooling of Cs acoms. This h" been

m,de po;;ible through, nomber of

development> in the areas such" ;pheriea!

quadrupole magnetic field, nit" high vacuum

upti,,] ch,mber, saturated ,bsorption

specuo;copy using diode I""" wavelength

locking of diode I"", and optie;. Some of theseissue; have been tackled for the first time in this

country.

An example nf these efforts is shown in Fig. 9

where we ;how locking of the diode I"er

w,velength about 10 MHz on the red side of the

cnoling transition of Cs. In Fig.IO, we show a

view of the magneto-optical trap ins"lIed as a

port of the la;" cooling facility in BARe. This

tr'ap is , major workhorse in our planned

experiments on the cold. ,nd tr'pped ",oms.

J 9 I--

Fig.! O. A ,i,w 'f ,h, magn"'-'pi,d 'mp J"igncd and dml,pcd in BARe

These experimems also include vecific"iom of a

numbee of aspects of lasee-arom interaction such

as non-clossical effects, quamum jumps and

phoron st"i"ics [19-21J. We have also begun

work on the nm genecation of teaps, i.e. "Clover

leaf' teaps required for tighter and losslessconfinemmt of neuml aroms as in the

experimems for obtaining Bose condensates [17].

Conclusions

The comrol of aroms, molecules and the

processes involving them is a central issue in the

comempocary spectroscopy. The classical

perception of spectroscopy is to "udy the way

the quamum systems behave, that is to

understand the aromiclmolecular processes; the

outcome of which always decided by the laws of

probability and stati"ics. In the new scenario of

"ultimate" control, we think in terms of setting

the cules of the game, pre-determining the

winner and modiIYing the spectroscopic

pcopcctics in such a way that the winner is always

rhe chosen one. The impacr of rhis "ncw wave"

in spectroscopy hos been so overwhelming rhat it

now encompasses a wide spewum of areos from

very basic ro very applied. This has also a

tremendous impact on many technologies

including nuclear technology, as shown by our

work on U-233 clean-up. The progcammes

undectaken by us hold promise for many suchaceas of intere" to our research centre.

Acknowledgement

The author thanks Dr. SK Sikka, DirectorSS&SG and Dr. N. Venkatramani, HeadL&PTD for their keen intere" in this work and

I 10 I--

continued encomagement. Many helpful

discu"ions with Dc. AP. Roy, fo,metiy Head,

Spectroscopy Division a'e geatefully

acknowledged. Thanks ace due to the colleagu",

and collabmatocs, M, LM. Gantayet, Dc. SA

Ahmad, D, KG. Manoha" Dc. A Venugopalan,

Ms AP. Ma,athe, Shci. S. Peadhan,

D, S.V. Lawande and Prof W.J. Meath.

References

(1) Kakodlm, BARC News Leue" No.182,Ma,'ch 1999.

(2) R. Chidambacam, XI Prof. Beahm Peakssh

Memocial Leerme, Indian Institute of

Metals, Bangato,e, August, 1995.

(3) B.N. Jagacap, LM. Gantayec and U.K.

Chauecjee, Proceedings of INSAT.97

(Kouayam, 1997), p.4.

(4) B.N. Jagatap, ISRAP Bull. 10,23 (1999).

(5) LM. Gantayec, B.N. Jagatap, KG.

Manoha, and K.c. Sahoo, Pmccedings of

INSAC.2000, 'Tower Imm Therium..

Statu;, Stra"gi" and Dimtions", (BARC,

2000), p.123.

(6) B.N. Jagatap, Pmceedings ofINSAc.2000,

"Power from Therium.. Status, Stra"gi" and

Dimtions", (BARC, 2000), p.241.

(7) B.N. Jagatap, LM. Gantayet, SA Ahmad,

A. Venugopalan, A. Ramonu)am, A.P.

Mawhe and B.K Ankush, Proceedings of

INSAc.2000, "Power frern Therium..

Statu;, Stra"gi" and Dimtions ", (BARC,

2000), p.235.

(8) AP. Mawhe, S. Peadhan, A Venugopalan,

KG. Manoh" and B.N. Jagatap,

Proceedings of INSAC.2000, "Power from

.Therium.. Status, Stra"gi" and Directions",

(BARC, 2000), p.238.

(9) B.N. Jagatap and LM. Gantayet,

Proceedings of INSAc.2000, "Power from

Thorium.. Status, Stra"gi" and Directions",

(BARC, 2000), p.243

(10) B.N. Jagatap, ISRAP Bull. 8, 2 (1997).

(11) B.N. Jagatap and W.J. Meath, J. Chern.Phys. 113, 1501 (2000).

(12) B.N. Jagatap and W.J. Meath, Chern. Phys.

Len. 258, 193 (1996).

(13) B.N. Jagatap, W.J. Meath, D. TiulebachHelmtich and R.P. Steec, J. Chern. Phys.+103, 121 (1995).

(14) B.N. Jagatap in "Sp"tro"op1' Perspecti""and Frontiers", ed. A.P. Roy, (NaMa,

1997),p.l06.

(15) B.N. Jagatap, in "Nonlinear opti,'s and Lam

Sp"troSt'opy", Ed. S.c. Abbi and S.A

Ahmad, (Naro,", 2000) p.I34.

(16) .N. Jagatap, KG. Manohat, S.G. Nakhate,A.P. Mawhe and S.A Ahmad, Cmc. So.

76,207 (1999).

(17) See fm example, B.N. Jagatap, A.P.

Mawhe, K.G. Manoha" R.c. Sethi and

S.A Ahm,d, in "Current Trends in Atomic

and Mol"ular Physics", Ed. KK Sad,

(Kluwe,.Plenum, NY, 2000) p.299.

(18) See fa, example, K.G. Manohac and B.N.

Jagatap, CUtS. Sc. 76,1420 (1999).

(19) S.V. Lawandeand B.N. Jagacap,Phys.Rev.A39, 683 (1989); Phys. Leu. A126, 335(1988).

Jill--

(20) B.N. Jagatap and S.V. Lawande,Phys. Rev.A44, 6030 (1991); Opt. Camm. 82, 17(1991).

(21) Q.V. Lawande; B.N. Jagatap and S.V.Lawande, Phys. Rev. A42, 4343 (1990).

the Department

important mmp'ime1itofdl'l'work pertains to

change the atomir;"altdifnolecular respolEe in afundflJrtbltalmanner to control

excitation, ionisation,9'1ddissociation. The thirdco'frJponerzt of our work is to

use lasers to control external degrees ~f.freedofn' sitch as positions and

velocities of "toms to obtain cooled ilnd trilpped"il,tofns for experiments on the

foundiltioilS of physics.

Dr B.N. Jagatap is the r~cipient of th~ Horni Bhabha Science,& Technology Award jartheyear 1998.

D, B.N Jagatap gtaduatdftMn the 211' batch 'fBARC TtainingS,'hMland abt11ined hit Ph.D

(Ph}'i,,) ftnm Univmity of Mumbai in 1988. He hat been atto"attd with the 1nlt,d""plinary

Cmt" ft' Chemitnl Phyti", Univmity af W"lttn Onta",. Canada. at Po" Doctotal hllaw

(1993-94) and VititingS"mti" (1999 and 2000-2001).

. . .

I 12 I-

BIOMEDICAL APPLICATIONS OF LASERS

P.K. GuptaBiomedical Applications Section, Centre for Advanced Technology

Indore, 452 013, India

Ab,"ract

The ose of la,ser,s jar medical diagnosLe, and jar therapy initialed by photo-excitalian <if nalUral

chromophures or exogenous photosensilisen, i,s ceceiring con,sidaable current altenlioo

Development' in these arca,e are expeclcd to hare profoand ilifluence on Ihe quality of health care,

Therejare, an aclivity in Ihe", areas wo,s' ,"arled al CAT in 1992-93, The initial efforts have been

to explore the use nfla",r indocedj/oarescence ,spectroscopy jar cancer diagnosis, ond ineesligate

the photo-hiological effect, of laser imldiatioll un lis'ing orgollisms, The article prorides an

oeereiew of the work can'ied oot at CAT in both the,ve areas, Some ~flhe new aclivities taken up at

CAT on devclopme'" of Icchniqoes for oplical imaging and loser micromanipulation of

micrn,snlpic obfects are aleu briefly dLecns,sed

Introduction

DUE TO THEIR SEVERAL

peoperties arc finding

applicatiom in medicine' The

use of lams in surgery, which started within a

ym of the invention of law, is now well

e"ablished, Lams have made pos,siblc minimally

invasive ulrn-peecise surgery with reduced

patient rnuma and hospirali,",ion time. The use

of lasers for medical diagnosis is also arrracting

considerable imcre>[ and signifIcant

advancements ace being made'" This wurk is

motivated by the fact that the onset and rhe

peogression of a disease are uften accompanied by

biochemicallmmphological changes, which can

be sensitively moniroted by laser spectroscopic

techniques, These rcchniqnes can therefore lead

to disease diagnosis at an early stage befme the

disease becomes difficult to manage, The other

important advantages offered by laser

spectroscopic techniques are their poremial fur

in-situ, near real time diagnosis and the use of

non-ionizing radiation which makes them

parTicularly suited fm mass screening and

r'epeated use withour any adv",e effcm,

Another area of growing interest is the use of

Ia>ers for non-surgical rherapeuric applications's

It exploits light induced activation of naturally

occurring or administered photosemitiser" A

good example is the fast developing

photodynamic therapy of cancer'" where

photo"citation of a rumor' localized drug leadsto selective demuction of tumor with mioimal

effect on healthy tissue, There are also

indications that selective photuexcirarion of

native chromophorc in rhe tissue may lead to

therapeuric effem, Clinical repons available inlitetature" as well as mults from Choithram

Hospital and Reswch Centct (CHRCt"',Indore have shown that inadiariun with lasers or

other narrow bandwidrh light sources can lead to

several thcrapeuric effects like accelerated wound

I 13 I--

healing, "eatmem of pulmona'}' nrhe«ulmis and

tcearmem of paio of various etiologies, The

mechanisms for these thetapeuric effeCtS arc nOt

vc'}' well undmtood. The dinid pmemial of

this cather simple and inexpeosive thmpeutic

modality is motivating considerable work in this

diteetion and sobstamial pmgcess is beingmade",

Realizing the profoond influence opri,,1

diagnosis and photntherapy can have on the

qoali'}' of health eare, work in these arca> w"initiared ar CAT in 1992-93. Several Stodies have

been made to investigate the photO-biologic-,1

effem of Iasec icradiation on liviog ocgaoisn1'

and to explore the me of laver induced

tlooreseence speCtroscopy fot cancer diagnosis,

Following stodies on sampb reswed at surgery

or binpsy from patietm wirh cancer of difTeretlt

arga",. systems suirable foc clinical use have been

develnped at CAT. One unit has been i",ralled

at a cancer screeuing center for screening patients

with neopl"m of urerine eervix. The other unit

h" been used to Cat'}' OUI a pilot study on 25

patients wirh histopatbologically confirmed

canw of oral eaviry and eocouraging multsobrained.

Work has also been initiated ,It CAT in some

oth" promising areas, One of these is the

developmem of teehni,]ues for optical in"ging

through turbid media. Thesc have rhe porential

ro pmvide sob-millimeter resolotion imaging

withom rhe need for ionizing radiation and

associated risks". The orher aetivi'}' taken op is

devdopment ofbser trap and mierobeam vcr up,

These set ops "'c finding widesp<ead applie",ionsin biomedicine for non-comaet

mieromanipolation of microscopic objem and

are expecred ro have an impact far beyond than

just being a new physic!1 tool for biological'esearch'".

In this article we first provide an owvi"w of thework cartied out at CAT on the use of laser

induced fluorcscence spwroscopy for canca

diagnosis. The r<-sults of the Sltldics carried out

to investig"te photo-hiologi,,1 effects of laser

i,mdiation on living ""ganisms '" pr"sented

n<xl. This is followed by a brief discussion of

some of tbe new acriviries taken up at CAT.

Laser Induced Fluorescence (LIF)

Spectroscopy for Diagnosis of Cancer

!.IF has heen us"d for diagnosing cancer in tWO

ways, One approach involves sYStemic

administration of" dntg like haemaotOporpby,in

deriv,nive (HpD) which is selectively mained by

rhe rumoL When photoexcited with light of

appropliare wavelength, the dntg localized in thetumor tloores<:es. This fluores<:cn<:e is used fot

detection and imaging of the tumoL

Pboroex"irotion a"o leads ro populating thc

triplet swe via intersystem cr",sing. The

molecule in exdted rripla Stare can dire"tly teact

with biomolecules 01 lead ro generation of singlet

oxygen, which is roxie tu the hoSt ti"ue. The

resulting de","etioo of the host tisslle is

exploited fa, phorody,,"mic thmpy of tumoL

hom the poiot of view of nse in diagnosis this

approach has cwo drawback" a po"ible dack

tOxicity of the drug and th" possibility of drug

induced photOsensitization. For example a major

,hawback with the lIse of HpD has been dntg-

induced photosmsitizarion of the skin

necessitating the patient to avoid light for a few

week>. Thae is therefore intereSt in devdoping

tumo,' mackm whm the tr'iplet State is mpldly

quenched and thcceby phorosensitizarion is

avoided. The Other approach, the one that h"

received mote attention in recent years, does not

use any <'Xogenou.s tumor markers. InStead it

exploitS fOt diagnosis the subtle ehangcs in thc

'peen-urn as well as the decay time of

fluoI",eenee from native tissuc> as it rransfolms

from normal to the malignant state. The studies

cartied Out over the laSt few years have shown

I 14 I--

considenble pwmi;e af this appmach fa.

diagnosis of .hc canee. of va.ious mgans like

m"ioc cmix, csoplugus, lung, b,'east, and onl

covity"

In-virm <t"die; at CA T

A schen",ic of the expccimental mangcmcmused at CAT for in-vino m,dies on

aotofluorescence spemoscupy of human ti»ucs is

shown in fig, 1. It mes a home-buih pulsed Nt

I"" the output of which is coupled to an opti,,1

fibet (core diamcte. 400~m) via dichmic minm

tI", ,'cflew Nt lase. rodi"ion (3370m) and

transmits Inogcc wavckogth fluoecsccncc ompur.

The powet of the lasre pube is manitated by a

beam splinre-phorodiode combioation, Thc

fluoecscence fcom .he tissue, kept io contact with

the fibre, is collected by thc "me fibre and

imaged 00 the emeance slit uf a scanning

monochmmatoL The wavelengtb-dispmcd light

" tbc exit slit of the monochmmatm is detected

by a phatomultiplire tube detector. A

micmpmce»o.-bascd spem developed at CAT

is being ",cd fm on-line acquisition of Nt lase.

powe. and fluoeesccncc specteal data, Pm

excitation/emission spectwscopic studics at othee

wavelengths a commercial spcwofluarometet

(SPEX, Flumolog II) w" used, In the following,

we bticfly summ"i" the eesuhs of the "udiescmied out at CAT on autofluoeescence fmm

tissues fmm diffeccnt otgans,

Fig 1 Sth"""," diag",m "fthe expaimem,,! rd-up ftr au"1Iu""""" ,p"""""py "ftisru",

I IS I--

PATIENTFig.2. &a""pl"'fl"h, in"g.,."djlua",«n«in"miryfl'N, /&"""i"d 'po'" afpai"dcan«"'maud",",,1 a,,1Un""i",ftam 12.parim""kmd","udam.P"im' numb"1" 4badcau",afal",lm (A);5" 8hadca"",afbuoalm"a" (BM)aud9" 12badcan",af"ng.u,(T).

Cancer of oral cavil]

Oral cane« is one of the most common cancers

in India and several other Sourh Asian counrries.

Laser induced fluorescence technique is

particularly wdl suited for early detection of oral

cancers due to the easy accessibility of this organ.

Studies on 337 nm excited autofluorescence

spectra from oral tissues (alveolus. buccal mucosa

and the tongue tissue samples obtained from

patients with the cancer of oral cavity) revealed

significant differences in the total. specrrally

integrated fluorescence intensity <L. I,(A) ;360 ,;

As 600 nm) &om cancerous and normal oral

tissue sites. In Fig. 2 we show a plot for the

spectrally integrated fluorescence intensity for

paired cancerous and adjoining normal tissue

sites of 12 patients (4 alveolus. 4 buccal mucosa

and 4 tongue) selected at random &om the

patienrs investigated. The considerably higher

values of L. I,(A) for normal tissue sites is

apparent. The mean value of L. I,(A) from

normal tissue sites was larger by a factor of 2

compared to that &om cancerous tissue sites. At

the other excitation wavelengths (A. : 300 nm

and 460 nm). no significant difference in

fluorescence yidd betWeen cancerous and normaloral tissue sites was observed.

With 337 nm excitation use ofLI,(A) alone as a

discrimination parameter provided exedlentdiscrimination betWeen cancerous and normal

oral tissue sites. The scatter plots for the values

L.I.(A) from all cancerous and the normal

tissue sites of the oral cavity arc shown in

Fig. 3. The sensitivity and specificity values for

I 16 t---

Ftc

0 '"

ORAL:'c'Fig.3. S",," plo,ft' ,bt 'p"",/ly imwa"d fI~mtm" in"mi,i" Jivm tan"rom IORAL-q and ~,,"a' IORAL-N)';", nf,}" nml ,auiry

"" ,ht ",,' >amp/',iu in""iga,,d. Th, b", ,how mtan "',, I "andad ,",iaNnn.

FI

(a.

u.)

2 4

1600

1400

11

0 ~ 00 Iii I::i:

I . I .I .

i +~. i ~ ~ t t t8 -9

PATIENT NUMBER

Fig. 4. &m" plotft, tht 'P«"aI/y in"f7a"dfl."""'mtt imtmiry nfpaim! ,"'urow and adjoining nanna/Im..t tinut>ampktJivm'"parim..

117 r-

dimiminating cancerous from notmal oral

rissues were -90% 0= the sample size

invesrigated". Use of a stepwise mulri-varia«

linear regression (MVLR) analysis with ten input

pmmetetS led to only a muginal improvement

in the discriminarion «suits". It is pertinent to

nore rhat having a discrimination parameter

based only on L,I,().) h", the advantage of a

much simpler experimental =gemcnt, since

no spectral resolution is required. It can however

be used as a good discrimination parameter only

whcn the diflerence in intensity values for

malignant and normal sites is much more than

rhe variations possible due to the various

cxperimental factOrs. Applicability to in-vivo

studics therefore needs to be investigated. The

UF based approach is expected to lead to an

early diagnosis and may allow detection of pre-

malignant alterations for which ptesently nodlective non-in=ive method exists.

Breast cancer

Autofluorescence spectroscopy of bre"'t tissue

with N, laser excitation sbowed thar rhe

cancerous tissue was considerably more

fluorescent comp=d to the normal and the

benign tumor tissue""'. A scatret plot for the

integrated fluorescence intensity from paired

cancerous sires and adjoining normal breast

tissue sires from 10 patients is shown in Fig. 4.

The ratio of the mean fluorescence intensity for

cancerous sites to that from normal and bcnign

tumor sites were .2.82 and 3.23 respectively in

the study involving 63 patients, 28 with ductalcarcinoma and 35 with fibroadenoma". With

300 nm and 488 nm excitation the canccrous

sites were more fluorescent rhan the normal.

However, no statistically significant diffetence

was observed in the fluorescence intensity of

cancerous and benign tumor sites. Therefore,while cancerous tissue could be discriminatcd

from normal with good sensitivity and

specificity, the discrimination results were poor

for discriminating cancerous from benign tumortissue. With 337 nm excitation, the use of

fluorescence intensity as a discrimination

parameter could howevcr, discriminate cancerous

tissue from, both normal and benign tumor

rissue, with sensitivity and specificity values of>99% ".

Excitation-emission spectroscopy" and time-resolved m=utements. carried. out on breast

tissue autofluorescence have revealed a significant

variation in the concentration of fluorophores in

malignant, benign tumor and normal tissue

types. Some of rhe predictions of the

spectroscopic analysis have been confirmed bybiochemical estimation". This variation in the

concentration of the fluorophores explained whythe discrimination resultS obtained with 337 nm

excitation we" much better compared to thatobtained with the use of orber excitation

wavelengrhs by other researchers".

Although b,,"'t cancer is not a superficial

disease, the UF based diagnosis of brmt canCer

can be conveniendy done during needlc biopsy.

This is of interest because X-ray mammography,

the best available means of detecting br=t

cancer at present, has two important drawbacks.

First it leads to a vety large number of false

positives, i.e., a vety large ptOportion (60-90%)

of mammograpbically abnormal detection turn

out to be benign upon invasive br=t biopsy,

leading to avoidable trauma and psychological

Stress to patients n. Secondly, frequent exposure

to ionizing x-ray tadiation during mammography

has potential hazards, howsoever remote. Laser

screeuing can be used without the adverse effects

",sociated with the use of ionizing radiation.

Furtbet, the tesultS of the in-vitro studies suggest

that the UF technique may offer much imptoved

specificity.

J 18 I--

Uterine cancer

The N, laset excited, autofluo<cscence spectta

fmm uwine tissue also showed significantdifferences between notmal and cancemus tissue.

The diffecences in the spectra we" quantified

using a stepwise MVLR analysis. Thedisccimination scote based on a 4 vatiable

MVLR analysis could disctiminate cancewus

sites fwm notmal with sensitivity and specificity

values of gteater than 85% in genetal and up to100% when the cancewus site showed red

fluorescence characteristic of endogenous

porphyrins".

Reasom for the spectra! differences

An understanding of the factors tesponsible for

the significant differences between rhe

autofluorestence spectra of cancewus, benign

tumoc and normal tissue sites is deady vety

important. This may nor only help in

oprimization of the diagnostic system but may

also pmvide valuable biochemical infmmarion on

the tissue. Comprehension of the spectral

differences requites that the fluowphores present

in the different tissue types ace identified and

their telative concentrations estimated.

The tesulrs of exciwion/ emission""',

synchwnous luminescences"'" and time-tesolvedstudies'" cattied out at CAT on breast and oral

cavity tissues suggest a significant vaciation in the

concentwion of the fluowphmes in the different

tissue types. In particular, the studies reveal that

while concentration of NADH is higher in

malignant breast tissues compaced to benigntumm and normal breast tissues", the "verse is

ttue for tissues fwm oral cavity where NADH

concentwion is higher in nmmal oral rissues".

These results have also been confirmed by

emymatic measurements of NADH

concentration in malignant and normal tissues

fwm breast and oral cavity". The differences in

fluowphore concentration inferrcd fwm

spectroscopic studies qualitatively explain the

observed spectral differences in the

autofluorescence spectra of the oral and breasttissues.

F;g.5. A "b,m";, vf,h, p""'yp' LIF ba;d 'pOemdmi,pdat C4Tjb, ;n-v;vvtNdi" vn can",d;agn"".

I 19 I--

In-vivo studies

A schematic of the UF based system developed

at CAT for in-vivo elinical studies is shown in

Fig. 5. It consists of a sealed-off N, laser (7 ns,

100 I'}, 10 Hz), an optical fiber probe, and a

gareable iotensified CCO detector. The

diagnostic probe, developed in-house is a fIber

bundle, whieh has tWOlegs; one contains a single

quartz tibet (NA 0.22, core diame<er 400l'm)

and the other contains six quartz fIbers (NA

0.22, core diamete< 400l'm). The central fiber

delivers excitation light to the tissue surface and

the six surrounding fibers colleCt tissne

fluorescence from the surface area directly

illuminated by the excitation light. The light

coming from the distal ends of the six collection

fIbers is imaged at the entrance slit of a

polychromator coupled to the intensifIed CCD.The fiber bundle is enclosed in an 55 tube (9

mm outer diameter). The tip of the probe is

shielded by a quartz optical flat (2 mm thick).

This is to provide a fixed distance betWeen the

tissue and the fibers for improved fluor=ence

collection and to protect contamination of the

fiber tips wirh body fluids. A photograph of the

a.=mbled unit is shown in Fig. 6.

One unit has been installed at a cancer screening

center at Indore and is being used to record

aurofluorescence spectra of different regions from

uterine cervix of patienrs screened for neoplasmof uterine cervix. The orher unit at CAT has

been used to car')' out a pilot stUdy on 25

patients with histopathologically confirmed

squamous cell carcinoma of oral caviryD. The

Fig. 6. Aph"r'Wnph "frhr LIFb""dry",m 4wkp,da<CATftrcnnmdingna<;'.

---

I 20 I--

discrimination algorithm developed could

differentiare rhe squamous cell carciuoma of rhe

oral caviry from normal "Iuamo", ti"ue wirh a

semiriviry and specificiry, towards cancer, of

86% and 63%, respectively, The resultS are

shown in Fig. 7. The reason for rhe relatively

lower specificiry values appears ro be rhe fact rhat

most of rhe parienes who panicipated in rhis

study were at an advanced stage of malignancies.

Some of rhe visually uninvolved sires assumed to

be nmmal may therefo« nOt be truly normal.

This follows because the normal appearing

ni/iII!!:!,:s=,QeQ.,...=

'C2'"£

region surrounding rhe cancero", rurnm may

have biochemical changes due to rhe field.effect

of rhe malignancy. Indeed, when rhe

discriminarion analysis was carried our on rhe

basis of the spectra averaged over all cancerous

sites and the spectra averaged over all normal

sites from a patient, a sensiriviry and specificirytowards cancer of 100% were obrained. The

remarkably good results obrained on sire

averaged spectra suggests rhar a few of rhe

normal sires had signarures very different from

the orher sites of the group.

1.0-1" ,i'~- .;. ~ :. . .. .~1?~.It :.~.

.1Ii'?" .'". J:. ,.. . ..... ........"

Site number

'..

(J0'0o~ 0

'1: 0

i'~i80~

0 ~o~:0 f!.{{p ~"8

..

0 0

0'J},t

. 0

I

F;g.7. Th, p"'"i,, p"babiliri" 'Ib,ing ""'ifi,d", 'q..m,m ,,1/ wdnoma (SCC)I" ,h, ,iou, ,i", in""iga,,d.

I 21 I--

Ii".I. III. .

0

O 0 00

g80

0

0

Studies on Photobioactivation

The u,e of light for non-,urgical rherapeutic

appli"",io", exploits photochemical reactions

initiated by pboto-excitation of natural

chromophores or exogenous drugs localized in

the tissue. Some well-known example.. of the

tberapeuuc use of light" are its use in

the teeatment of psoriasis, neonatal jaundice, skin

tuberculo,is, photodynamic therapy of cancer,

etc. Several ",;carchers have also reported mat

inadiation wirh narrow bandwidth light Oaser)

can have profound effect on cellular cultures and

animal models' and can alw lead to rherapeutic

effects in humans'."', like, accelerated wound

hcaling, treatment of pain nf different origins,

etc.. Although the usage of lasm for non-,urgical

laser therapeutic applicatinns is gtowing it has

not yet become an established clinical modality"

because the mechanisms for many of rhe photo-

thetapeutic effem ace not vety well undersrood.

The clinical porential of mi, tatber simple and

inexpensive therapeutic modality is motivatingconsiderable work in this direction and

substantial progtess is being made". It is

perrinent to note rhat for these phoro-therapeuric

applications any conventional light source

generating the appropriate wavelength and with

the desired paramerers (en«gy, pulse durationetc.) can be used. However, rhe berrer control on

laser light characreristics ofren makC1i

phototherapy more convenient with rhe use oflasers.

At CAT ,everal studies have been canied out to

investigate the effect of laser radiarion on cellularculrures and animal models. Our studies" on rhe

effecr of N, laser irradiation on the skin of

animal models (albino rabbirs and mice) showed

that N, laser inadiation at cerrain doses can lead

to a proliferation of cells in rhe active epidermal

layer of me rabbit/mice skin. Such proliferation

of cells can comribute to fuster healing of me

wounds reponed in several clinical studies.

Furmer, me fact mat an inhibition of cell

proliferation was observed at higher dose

highlights the importance of a carefrd study of

me parametric dependence in order ro elicit me

dC1iired clinical response. Since macrophages play

an important role in rhe process of wound

healing, effi:cr of light on macrophagC1i bas also

been studied and stimularion of macrophagC1i

observed following He-Ne laser inadiation".

The studi", on narrow bandwidm lighr <fTem on

E-coli baCterial ')'stems canied Out at CAT have

provided two inreresting remlrs. First, ir has beenobserved" that He-Ne laser irradiation can

stimulate respiratory electron transfer process

through change in redox stace of mpirarory

components. Since me production of ATP, the

source of cellular energy, i, linked to eleCtrontransfer such stimulation can lead to enhanced

metabolism. Experiments canied our wing

different inhibirors for me respiratory chain

components ,uggesr that the primacy

phororecepror ar He-Ne las« wavelength is

cytochrome d. Secondly, it has been observed"'"

thar He-Ne laser (632.8nm) pee-irradiation

induces protection rowards uve irradiation in

several Ecoli strains. The magnitude of

protection was found to depend on He-Ne laser

imensity, exposute rime and the period of

incubation between He-Ne laser exposure aud

subsequem uve inadiation. The results also

suggest involvement of singler oxygen in the He-

Ne laser induced protecrion. Recent experiments

with E-Co/i strain KY706/pPL-I 'uggesr mat rhe

induced protection is due to He-Ne laser

irradiacion induced induction of ph, gene and

acrivarion of 50S repair.

SrudiC1i carried our on red blood cell lysate"

showed that N, laser inadiation induces

oxidarion of hemoproreins. Mechanistic studies

and experiments wim deoxygenaced ted blood

cell lysate rule out involvecnem of any reacrive

oxygen species and suggests mat rhe proms is

122 I-

photOchemical and not intrinsic photosensitiw

induced photodynamic «action.. A singl~ cell gel

electwphmesis '" up was also developed and

med to investig"e UVA induced DNA damage

in mice pedton,,1 macwphages"'.

Studies on photodynamic effect of

photnsensidsm on cellulae cultutes and animal

have also been initiated" CAT. Studies wece

c",ied out on the photodynamic inactindon of

Bacillus ,"brill, cells by He-Ne la"e itradi"ion in

p«sence of methylene blue (MB) and toludine

blne (TB). Results show th" outside: the cell

both MB and TB lead to photodynamic

genemion of singlet oxygen causing a dec«ase in

cell memb"ne fludity. Howevet, whereas TBeenuins outside ehe cell and does nm lead to

genecation of feee "dicals, in MB mediated

photodynamk action, supewxide cadica!

generated int"cellulacly is the majoe contributm

to the cell damage". Investig"ions have also been

c",ied out photodynamic effect of MC540 and

AlA on cell lines of epithelial neoplasm and on

AlA induced accumulation of pwtopotphydn

(Pp) intumm and skin of fibwsaccoma beating

mice. Effect of glucose p«-treatment and

feactionated delivery of AlA on Pp accumulaeion

in tumoe and tumoe to skin mio of Pp was

investigated. A pilot study on photodynamic

thecapy of animal tumms has also been weied

our'". This was a collaboeative wack with a gwup

" RMC to chatacteei" a photosensitisee dcug

p"ented jointly by Radiation Medicine Centre

(RMC), Mnmbai, and liT, Mnmbai.

Development of Techniques for Optical

Imaging

Optical imaging has the pmential w pwvide sub-

millimme eesolution imaging without the need

foe ionizing "di"ion and associated eisks. The

fundamental pwblem with optical imaging is

th" in contrast w Hays optical photons ace

StCongly scattered in tissue, which leads to a

bluccing of ehe image. Sevecal appwaches can be

used to pick out the useful image beating light

fwm the backgwund-scatteeed light" One

appwach is w exploit the fact that the scattered

light emerges fwm ehe dssue in all di«ctions and

also takes longer time to emerge as compa«d w

the component of light which does not undergo

any scattering oe is peedominantly foewatd

scattered. Therefo«, using sp"ial filtecs and by

use of ultta-shott «mpmal gates (of picosecond I

sub-pico"cond duration) image beating

components can be filte«d out. Though ehe

'patial «solution achievable in these techniques

is vel)' high (few tens of micwns), these can not

be used fm imaging thwugh laege dssue

thickness since the amount of image beaeing

lighe hils off exponentially with the inc«ase in

the thickness of the scatteeing medium. One

appwach to add«ss this pwblem is to ',electively

amplifY the image beacing light using non-lineae

optical eechniques. Experiments on optical

imaging through eutbid media have been c",ied

our ar CAT using a Streak Cameca with tempoca!

«wlution of - 10 ps and also by urilizingstimulated Raman scattering (SRS) appwach foe

rime garing. A sparial «solution of -300 ~m has

been obsecved in rhe present set-up.

Development of Laser Optical Trap-

Microbeam Ser Up

Development of laser trap and micwbeam set up

has also been taken up ar CAT becau" it is

finding widespread applications in biomedicine

for non-contact micwmanipularion of

micwscopic objects". Laser micwbeam is

essentially a pulsed lasee beam coupled to a

micwscope. The lacge intensities (of up to 10"

W/cm' with UV lasec micwbeam) generated at

rhe focal point of the large numerical apetture

micwscope objecrive can be used to Cut,

perforate m fuse micwscopic objects with sub-

micwmetee accuracy. As these intensities arise

123 I-

only ac the focal point. it is possible to work

within the depth of a transpacent object without

opening it. Optical tWeeze, or laser optical trap

uses the light of a CW infrared laser for transpOt(

of microscopic objecrs. Here. the gradient forces

arising due to the lacge gradient of light intensity

in rhe focussed laser beam and the resulting

gradient in the light pressure and the electric

field ace used to trap microscopic objecrs at the

focal point of the laset beam. Unlike mechanical

microtools. the optical trap is gentle and

absolurely stetile and can be used to capture,

move and position single cells or subcellular

panicles without direct contact or significant

damage. A laset trap set up has recently been

made operarional ar CAT and used to trap

poiystyrene microsphetes and motile bacteria

"'""damo"", and E-Coh).

Conclusions

There exist considerable current interest in the

development oflaser-based techniques for in-,itu.

near teal time diagnosis. Sevetal studies havebeen carried our at CAT on laser induced

fluorescence of tissues resected at surgety or

biopsy from pacients suffering from cancer of

oral cavity. breast or uterus. These studies have

provided very encouraging resulrs ondiscrimination of cancerous tissue sites from

benign tUmor tissue Ot normal tissue sites. N,

laser based systems have been developed for

clinical studies and ace being used for in-vivo

studies on the diagnosis of cancer of oral cavity

and urerine cervix. A pilot study on 25 patienrs

wirh histopathologically confirmed squamous

cell carcinoma of oral cavity has been completed

and satisfactory discrimination results obtained.

Photobioactivation using endogenous and

exogenous chromophores also holds considerable

promise for a variety of therapeutic applications.

However, realizations of this potential requirescareful studies on the effects of narrow

bandwidth light on celiular cultUres and animal

models so that the mechanisms tesponsible for

the various photo-therapeutic effecrs are betterunderstood. Several studies in this direction have

also been carried out ac CAT.

Acknowledgments

The author will like to thank his colleagues at

Biomedical Applications Section and Laser

Applications and Electronics Division, CAT whohave contributed to the wack described in the

paper. It is also a pleasure to thank Dr. D. D.

Bhawalka<. Ditectot. CAT for his suppott and

encouragement.

References

1. See for example (i) Wolbacsht, M. L, ed.."Laserapplicationsin medicineand biology",Vol. ]-5, Plenum Press, New York, 1971,

1974.1977.1989 and 199]; (il) Caro. R C.

and Choy. D. S. J.. (Guest eds.) Optics andPhotonics News. Special issueon Optics andLight in Medicine, Oct. 92, pp. 9.44 and(iil) Gupta, P. K.. in "Medical Physics forHuman Health Cace". (eds. Bhamagat. P.K..Pradhan. A S., and Reddy. A. R). ScientifiePublishers,Jodhpur, 1997, pp. 143-161 andreferencestherein.

2. Servick-Muraca,E.. and Benaron, D., (eds.).

"OSA Trends in Optics and Photonics onBiomedical Optical Spectroscopy andDiagnostics", Optical Society of America.Washington, D.C.. Vol. 3. 1996.

3. Wagnieres,G. A, Srar, W. M.. and Wilson,B. C.. Photochem. PhotobioI. 1998. 68.603-632.

4. Special Section: BiomedicalApplications ofLasers,CurroSci.. 1999,77,885-941.

I 24 I--

5. Karu, T I., "Phorobiology oflow-power laser

rherapy", Harwood Aeademic Publishers,

London, 1989.

6. Ohshirao, T, and Calderhead, R. G., "Low

level laser therapy a prKrical inrroducrion",

John Wiley and Sons, Chichester, 1988;

Ohshirao, T, "Low reacrive level laser

therapy: pracrical applicarions", John Wileyand Sam, Chichester, 1991.

7. Hender,"n, B. W., and Dougherty, T J.,

(eds.), "Phorodynamic Therapy Basic

Principles and Applicarions", Ma<eel Dekker,

NewYork,1992.

8. Baxrer, G. D., "Therapeuric lasers, Theoty

and PraCtice", Chmchill Livingsrone,

Edinbmgh,1994.

9. Yamamoto, H., Okunaka, T, Furukawa, K,

Hiyoshi, T, Konaka, c., and Kato, H.,

Cun. Sci., 1999,77,894-903.

10. Bhagwanani, N. S., Laser News, 1995,6(3),

8-12, and 6(4), 6-8.

11. Gupra, P. K., and Bhawalkar, D. D., Cmf.Sci., 1999,77,925-933.

12.Karu, T I., J. Phorochem. Phorobiol. B:BioI., 1999,49,1-17.

13. Rudolph, W., and Kempe, M., J. Mod.

Optics, 1997,44,1617-1642.

14. Greulich, K. 0., "Micromanipulation bylight in biology and medicine", BirkhauserVerlag, Berlin, 1999.

15. Majumder, S. K., Gupta, P. K and Uppal,A.,LasersLifeSci,1999,8,211-227.

16. Majumder, S. K., Gupra, P. K and Uppal,A, in "Oprical Diagnosrics of BiologicalFluids III", (ed. Prienhev, A V.), Proc. Soc.

Phoro-Opf. 1nstrum. Eng., 1998, 3252, pp.158-168.

17. Majumder, S. K, Uppal, A., and Gupra, P.K., in "Trends in Optics and PhotonicsVolume on Biomedical Speetroscopyand

Diagnosis" Eds. Benavon, D., and Sevick-Muraca, E., Oprical Societyof America,Vol.3,1996, pp. 142-146.

18. Gupta, P.K., Majumder, S. K., and Uppal,A."LasersSurg.Med., 1997,21, 417-422.

19. Majumder, S. K, Gupta, P. K, Jain, B., and

Uppal, A, Lasers Life Sci, 1999, 8, 249-264.

20. Jain, B., Majumder, S. K, Gupta, P. K,

Lasers Life Sci., 1998,8,163-173.

21. Uppal, A, Majumder, S. K, and Gupta, P.

K, Proc. Narional Laser Sympos., 1998, !IT

Kanpm, pp. 219-220.

22. Katz, A, Alfano, R. R., in Serviek-Muraca,

E., and Benaron, D., (eds.), "OSA Trends in

Oprics and Photonics on Biomedical Oprical

Spectroscopy and Diagnosrics", Optical

Society of America, Washington, D.c.,

1996, Vol. 3. pp. 132-133, and referencestherein.

23. Maranro, G., Scientific American, 1996,275,113.

24. Majumder, S. K, Uppal, A, and Gupta,P.K, Cun. Sci., 1996,70,833-836.

25. Majumder, S. K., and Gupta, P. K., in"Optical Diagnosrics of Biological FluidsIII", (ed. Priezzhev,A V.), Proc. Soc.Phoro-

Opt. Instrum. Eng., 1998, 3252, pp. 169-178.

26. Majumder, S. K., and Gupta, P. K, LasersLifeSci., 2000, 9, 143-152

27. Majumder, S. K., Mohanty, S. K, Ghosh,N., Gupta, P. K, Jain, D. K, and Khan, F.,Cun. Sci., (in press).

I 25 /--

28. Regan, J. D., and Parcish, J. A., (eds.), "The

science of photomedicine", Plenum P<ess,

NewYork,1982.

29. Basford, J. R., Lasers Surg. Med., 1995, 16,

331-342.

30. Agnihotri, S., Sachdeo, S., Sharma, A.,Kemi, Y., and Gupta, P. K., LasersLifeSci,1997,7,227-235.

31. Bansal, H., Dubey, A., and Gupta, P. K.,

Proc. National Laser Sympos., !IT K,npur,

1998, pp. 227-228.

32. Dubey, A., Gupta, P. K, and Bhatti, S.,LasersLifeSci, 1997, 7,173-180.

33. Kohli, R., Gupta, P. K, and Dubey, A., in"Biologiceffecrsof light 1995", (eds.Holick,M. F. and Jung, E.G.), Walter de Groyterand Co. Berlin, 1996, pp., 243-245.

34. Kohli, R., Gupta, P. K, and Dubey, A ,Radiation Research,2000,153,181-185.

35. Murali Krishna, c., Bose,B., and Gupta, P.K, Radiation Research,2000, 153,411-415.

36. Bock, c., Dubey, A., Greulich, K 0., and

Gupta, P. K, Mutation Research,1999, 439,171-181.

37. Dubey, A., Bansal, H., and Gupta, P. K,Indian J Biochem. & Biophysics,2000, 37,245-250.

38. Murogesan, S., Gupta, P. K, Sharma, M.,Dube, A., Noronha, O. P. D., Samuel, A.

M., Sherry, S. J., Srivastava, S., Khare, R.,

Bharnagor, R., and Parhak, S., Presented atXV A>ia Pacific Cancer Conference, 12-15December, 1999, Cancer Institute, Chennai.

Abaut the auth"..

(MSr., Lurk",w Uni"mity, 1973) i"iucd the mtwhile La", Sreti", BARC, in

,ating thwugh the BARC haining Seh"l. Hi, ""a"h intem", while at BARC,

included n,,-line., aptiealfrequency ,,""minn, CO, I.,m and CO, /a", pumped malew/a, g"

Imm. Dr. Gupta war at H"int Watt Uni",ri'y, UK frum N"emb" 1979 to N"emb" 1981

" a Camm"wealth Schola"hip Awa,d and late' nn a pnttdnttocal ftllawrhip dueing 1988-89

He ubtained hir Ph.D. "'pre fram H"int Watt Univmity in 1981 ft' hit w"k nn 4fttient mid-

infra"d genreati" by optical pumping mnlreul., garer and ",n-line., aptieal mixing.

Dr. Gupta m"ed tn Cen"eftcAdvanrrd (CAT), Indu", in Ma"h 1990. At CAT,

he initiated w"k nn CO, I.", pumpedfir,-infra"d larm and an biamedieal applieati"r aJlmm. He pmently hradr the

Biumedical Applieati'" Seai", at CA T, D,. Gupta h., raclie"eaintd the 1988 NS Satyamucthy Mem"ia/ awaed of

the Indian PhyrirrA",tiatinn fir, hit "m,ibutia", un mid-infra"d "hennt "U"".

. . .

I 26 I--

SCALING OF THE STEADY STATE ANDSTABILITY BEHAVIOUR OFSINGLE-PHASE NATURALCIRCULATION SYSTEMS

P.K. Vijayan

Reactor Engineering DivisionBhabha Atomic Research Centre

Abstract

Scaling methods for both the steady state and stability behaviour of single-pha" natural

circulation systems have been pmented For single-phase systems, simulation of the steady state

flow can be achieved by preservingjust one nondimensional parameter. Simulation of the stobility

behaviour requim geometric .similarity in addition to the similarity of the physical parameters

appearing in the governing equations. The scaling laws proposed have been tested with

experimental data on single-phwe natural circulation.

Introduction

NATURAL CIRCULATION IS

being inm"ingly employed in m,ny

innovative designs of nucleac ceactot

cooling systems. The basic ,dvanrage of natural

citculation systems is the enhanced Bfety due to

its passive nature. One of the basic tequitements,

which arise prior to the incorporation of such

systems in nuclear reactors, is the assessment of

theit petfotmance. Generally, in the nucleat field

the assessment is carried out by nlidated

compute< codes. Code validation is m",lly donewith data obtained from scaled test faciliti". The

topic of the present paper is the scaling laws used

for constructing such scaled facilities fat

simulating single-phase natural circuladon. Such

a scaled facility in nuclear parlance is also known

as an integral test facility (ITF).

Scaling laws make possible the comparison of the

performance of different natural circulation

systems and to extrapolate the data fmm small

scale to pmtotype systems. Scaling laws fm

nuclear reactot systems are arrived at using the

goveming consecvotion equ,dons. Pioneering

work in the field of scaling laws for nuclear

rcocmr systems bY< been ""ied out by

Nahavandi et a!. (1979), Zube< (1980) and

Heisler (1982). The scaling law pmposed by

Zuber is also known as the power-to-volume

scaling philosophy and is widely used for the

construction of scaled test facilities simulating

nucleat teactot systems. Power m volume scaling

c,n be applied to both forced and natural

circulation systems. However, the power-to-

volume scaling philosophy has cenain inherent

dismrtions (especially in downsized

components), which can suppeess cenain natueal

circulation specific phenomena like the

instability (Nayak et a!. (1998)). Hence it is

necessary m examine the scaling laws which ace

specific to natural circulation. In the present

I 27 I--

papee, ehe eeponed ,ealing hw, foe ,ingle-phase

nameal eieeuhdon loop' ace ceviewed wieh

e"peet to theie u,e foe pcedicting the "eady "ate

and mbility behaviom. Then "",ling pcocedm"

foe ,ingle and two-phase 'y""'" ace pe"emed

and te"ed agaimt the available data on the "eady

"atc and "ability petfotmance of nameal

cieculation loop,. Thi, execci" has ,hown that

the "eady "ate behaviom of ,ingle-phase loop'

can be ,imulated by a ,Ingle dimemionb,

paeamecec. The ,imulation of the "ability

behavioue cequice, ,imulation of at I"'t thcee

dimemionle" paramet'" in addition to

geometcic "aling. Foe the "ability behaviom,

,caling of the chaeacteei"ic equation (obtained

by the lineae mbility analy,i, method) appea" to

be the appcopciate method foe achieving

,imilarity.

Review of Scaling Laws

Sevec.aI ,caling law, have alceady been pcopo"d

foe the d"ign of ,ealed loop' ,imulating nameal

ciccuhtion phenomenon (Zubec (1980), Hei,1ec

(1982) and j,hii-Kataoka (1984)). All the theee

,ealing law, ace decived fcom the goveming

diffecential equadom. One of the pcoblem,

a"ociated wieh the" ,caling law, i, thae the

numbec of ,imiladty gcoup' ace too many and

they do not pcovide "eady mte oe "ability

,olutiom in teem, of the pcopo,ed ,imiladty

geoup'. Thecefoce, twing of the" "aling law,

with the available expecimemal data i, eathee

difficuh wiehout ehe u" of 'y"em cod". Thi,

ad", due to ehe face that moce than one ,caling

paeametee i, a function of the flow rate, which

fot a natutal citculation loop i, not known

apeioei. To oveccome this pcoblem, Vijayan et aI.

(1992) pcopo,ed a "aling pcocedme by which

the "eady "ate flow eate can be obtained as a

function of jmt one ,imilaeity gcoup. Thi,

pcocedme has been extended cecendy to

nonuniform diameter loop' (Vijayan (1999), ,ee

aho "ction 3). They have aho obtained the

"ability ,olution in teems of the ,imilaeity

gcoup',

Proposed Scaling Laws for Single-PhaseNatural Circulation

~OTTJ It COOLER L:~i

\--~""8. -

l"',8. ""s.

"

~ :.~ ~!

F;g. 1. 5th",",,;, 4 non-uni/i= diam"" naMa1c;mdatiun IMp

Comidec a ,imple nonunifoem diametec naemal

cicculaeion loop" ,hown in Fig. 1 with ahoeizomal heat 'omce at the bottom and a

hoeizontal heat ,ink at the top. The heat ,ink i,

maintained by pcoviding cooling watet to the

secondary ,ide of the coolee at a 'pecified inlet

tempmmce ofT,. In thi, analy,i" the "condaty

side tempmtme is a"umed to cemain comtanr.The heat flux at the heat 'outce i, maintained

comtant. Aswming the loop to be filled with an

I 28 I--

incomp,""ible fluid of constant pmpetties

except density (Bou"inesq appmximation wheco

density is assumed m vaty as p,p,[I-~(T-T)])

with negligible heat lo"es, axial conduction and

viscous heating effects, the governing differential

equarions can be written as

aw =0.as

(1)

dW W' N (fL )I

r-=gp,pfTdz--L: -+K ,.dt 2p, i.1 D i Ai..(2)

where r=LL/A,. It is also po"ible ro absorb rhe

local pre"ure 10" coefficient, K, into an

equivalent lengrh, Le, such thac 1(, . ~Le/D,.

With this cottection, the momentum equation

can be written a"

dW W' N

(

fL)

r-=gp,pfTdz--L: 4dt 2p, i.1 DA i

Similarly, the energy equation for the different

sections of the loop is given."

aT W aT qhPh-+--=-at P,Ah as Ahp,Cp

Heater

..(4a)

'!I.+~'!I.=_UP,(T-TJat p,A, as A,p,Cp

Cooler

..(4b)

'!I.+~'!I.=oat p,Apas

Pipe

..(4c)

The above equations can be non-dimensionalised

using the following sub"itutions.

WiV=-;

W"e- T-T, ;

- (~Th)"s-3-. 2-3-.

- H' - H'

z=-'-.a=.:iandd =~t,' 'A, 'D,

(5)

where t" A, and D, are respectively the

referencevaluesof time, flow rate and hydraulicdiameter defined as

v,p,.t=-,, W"

A =..! i;AL =~, L, '.i " L,and

I ND, =-L:D,L,L, ,.i

...(6)

..(3)

It is easy to see that the reference time is nothing

bur the loop circulation time. D, and A, are

respectively the length average hydraulic

diameter and flow area of the loop and the total

circulation length, L"LL,. In case of negligible

local pressure losses, L(L",), becomes equal to the

total circulation length, L, of the loop. The non-

dimensional equations can be expressed as;

r diV = Grm~edZ _!:L. 0)' i (fl'ff )dz Re;, D, 2 i-I da2 i

..(7)

~.j.~~=~az ah as Vh

heater. ..(8a)

~+~~=-StP,L, eaz a, as A,

cooler. ..(8b)

~+~~=oaz ap as

pipes (8c)

where y=Ll/a" I, '!,/L" (l"),,(L,,),IL,,

Gr,"-D.'p,'~g~T/~', and St,Nu/Re.Pr.Assuming fully developed forced flowcorrelations are valid, the friction facror, ~can be

expressed as

I 29 I--

P pW-b

J,~Ref~Re:,(d/a)f'

where p=64 and b=1 for laminar flow and

"mming Bl",im coHelation to be valid fo<

turbulent flow p and bare re'pectively 0.316 and

0.25. In a non-unifomi diameter loop, it i,

pm,ible that >ame pipe ,ectiom are in turbulentflow (Re>4000) and ,orne in laminar flow

(Re<2000) and "ill othm in Hamition flow

(2000<Re<4000). Howevet, if we a"ume the

entir; length of the loop to be under either

laminar or turbulent flow condition>, then

equation (7) can be expre"ed a,

..(9)"eady "ate ,olutiom, the integral in equation

(12) can be calculated a, qOdZ = l,for the loop

,hown in Fig. 1. Hence, the "eady "ate flow rate

can be expre"ed a,

Re,,=[~~:]~ =c(~:J (14)

where C=(2/p)' and r = 1I(3-b). Thu" knowing

rhe value of p and b the comtan" C and r in

equation (14) can be wimated. For laminar flow

(where p=64, and b=1) equation (14) can bercwrirrcn a,

rdw=Grmfedz--'-'-~f. [~ J= Grm fedz-pNc;W'"

dT Re:. D, 2Re:, ,,' d"'aH, Re;, 2Re:,

whete Nc; i, a geometric parameter defined

N L, ..[f.( I'ff )" ,.=[)L.., d '" H ., ,,' a ,

Steady ,tate mlution

The governing equation> for the "eady >tate

condition ate obrained by dropping the time

dependcnt tenm. Aha, by definition OJ (the non.

dimen>ional flow me) i, unity at "eady >tate.

Therefore, the "eady "ate momentum and

energy equatiom can be written a"

Gr~ qOdZ = pN,;Re" 2 Re"

J.~~~ for hearer; J.~~-StP,Lteah dS Vh a, dS A,

for cooler and J.~ = 0 fo<pipe, . ..(13)ap dS

The "eady "ate ,olution> for the temperature ofthe variom 'egment' of the loop can be obtainedfrom Eq. (13) (,ee Vijayan (1999». U,ing these

..(10)

.(11)

Re"" = 0.1768[Grm]"'.N"

..(15)

Similarly, ",uming Bla"im friction factor

coHelation (p=0.316 and b=0.25) to be valid for

turbulent flow we can obtain the following

equation

Re".,=1.96[~:'J3M.(16)

..(12)

In the tramition region, one can expecr a

continuou' change in the exponent of equation

(14) from 0.5 to 0.364 " well" for the con"ant

from 0.1768 to 1.96. It may be noted that both

equatiom (15) and (16) are rhe exact ,olution> of

equation (12) ",uming the >ame friction factor

coHelation to be applicable to the entire loop.

For clo,ed loop" often rhe >ame friction factor

co<relarion may not be applicable for the entire

loop even if rhe loop i, fully laminar 0< fully

turbulent. An example i, a fully laminar loop

with part of the loop having rectangular cro"

,ection and remaining part having circular cro"

>cction. Hence, one h" to keep in mind the

I 30 I--

assumptions made in deriving the relationship

(14) while applying it.

The relationship expressed by Eq. (14) is derived

for a rectangular loop with both the heater and

cooler having the horizontal otientation. Forother orientations also, it can he easily shown

that the same relationship holds good if the loop

height in the definition of the Gr. is replacedwith the centre-line elevation difference between

the cooler and the heater, !;z (see Vijayan et a!.

(2000». The same is true for other loop

geometries like the figure-of-eight loop used in

Pressurised Heavy Water Reactors (PHWRs).

For the figure-of-eight loop, the heater power

used in the Gr. is the total power of both

heaters. The equarions are also applicable for

identical parallel-channel or parallel-loops

systems if the parallel channels/loops are replaced

by an equivalent parh having the same hydraulicdiameter and rotal flow area.

Stability behaviour

Equation (14) has shown that simulation of the

steady state behaviour is possible by simulating

Gr.lN, for any natural circulation loop. The

transient and stability behaviour, however, are

described by equations (8) and (10). Substituting

the steady state solution, the transient

momentum equation can be rewritten as

y ~~ ~ (9&1Z-m2-b)(p12)6 {GrF /NP J(17)

From equations (17) and (8), it is obvious that

the transient and stability behaviours are

governed by the physical paramerers Gr., St and

the geometric parameters of N" y, V/V., P,l./A,

and the area ratio a;. To reduce the number of

independent parameters, it is customaty to

combine St and Pel, / A, into a single

dimensionlessparameter called Sr. Similarly,Gr.and N, can be combined as Gr.""'/N,"'" so rhatthe transient and stability behaviour can be

expressedas

(Grbl/3-bl V

Jm(r)=/ ~/(3-bl,Stm,...J..,yanda, (18)

No Vb

Further reducrion in the number of independent

parameters is possible for special cases. For

example, with a uniform diameter loop,

(V,/Vh)=(L,/Lhh aFI, y=1 and No =L,/D

so that

(Grbl(3-bl l.

Joo(,)=f ( mY/(3-bl,Stmand J.. (19)l.,/D l.h

In addition ro l./l" other length scales also affect

the stability behaviour. This can be established

by carrying out a linear stability analysis. In this

method, the loop flow rate and temperature are

perturbed as

oo~oo,,+;;;eem and8=8,,+6Ee" (20)

where E is a small quantiry, m and Ii are the

amplitudes of the flow and tempmture

disturbances respectively, and n is the growth

rate of the perturbations. Substituting Eq. (20)

in equations (10) and (17), and using the

continuity of temperature perturbation in

various segments as the boundaty condition, the

characteristic equation for the stability behaviour

can be derived. The characreristic equarion for a

uniform diameter loop with horizontal heat

source and sink can be expressed as Y(n)=O

(Vijayan and Ausrregesilo (1994», where

Y(n)=n (p12)3I(3-b)(Grm)bI(3-b)(DIL,)3/(3-b)hl/(n,Stm)+2-b}

(21)

I 31 I--

where ljI(n,Stm) = ~{1-exP(-nH/L,)}exp(-nS,H/L,) (8h::8,)andnH 0)

(Bh::B')=iL{exp(-nLh IL,)-I} +(exp{-n(S,-S, -Sh)H IL,}-I) B+Cw ~ D

B =...!:Lexp(-nS,H/L,){I-exp(nLhIL,)}; C = (ehl)"Stm[1-exp{-nL, IL,)]nLh n

and D = exp{StmL,/L,}-exp(-n) where

S,=L/H and S, =s/H. 5" 5, and 5, are the

dimensionless disrances from the origin (i.e. 5=0

in Fig. I) in anti-dockwise direcrion. It is

ohvious from equation (21) rhar, apart from the

paramerers lisred in (19), the ratios ofthe lengrhs

are also required to be preserved to simulate the

srability behaviour.

Testing of Scaling Laws

The scaling laws presented in secrion 3 are reseed

againsr experimenral dara for borh sready srate

and srability behaviour.

Steady state behaviour

The sready state scaling laws were tesred with

data obtained from simple low pressure and high

pressure loops. The data induded both in-house

experimenral data and those compiled fromliterature.

In-house data

For tesring of the scaling laws, experimenrs were

carried out in three uniform diameter rectangular

loops with horizonral heater and horizonral

coolet (Viiaran et al. (1992». These loops (see

Fig. 2) had the same length (both total and

componenr lengths) and height bur differenr

inrernal diameters. These experiments helped to

esrablish the adequacy of Gr,/N, as the scaling

parameter fat the sready srate flow as the data

from the three loops could be expressed in the

,,"". t'i=c"':::L'i

L-;+ ~"'rom

I

'

><EATER

"""'. t_--=~Cl- "'::~},

I',:~'",

Fig.2 Unifb~ diom"" /",p, with difJiant """",,1dioMm and idinti,,! kngth, {oii dim..,i,n; in 'mY

10'

10' 10" 10"1.' QrmD/~ 1.'

Fig.3 SaMY ;taa jWw in unifb~ diom"" /"01'

fotm ofEq, (14) with the same value ofC and r(see Fig. 3). Suhsequently, experiments wereconducred ro srudy the effect of the orienrationof the heater and rhe cooler as differenr types ofnudear reactors have different orienrarions

of the heat source (core)and the heat sink (sream

J 32 t--

generator). For =ple, PHWRs havehoriwnral core and verrieal Steam generarors,PWRs have verrieal core and vertical Steam

generarors and WERs have verrieal core andhoriwnral Steamgenerarors. In view of this. thehearer and cooler orienrarions Studied included

the horiwnral hearer horiwnral cooler (HHHC),horizontal heater vertieal cooler (HHVC),Vertieal heatet horizonral cooler (VHHC)and verrieal heater vertieal cooler (VHVC).

Further derails of the experimental loop (seeFigA) and dara generated can he obtained from

'Bade (2000) and Vijayan er al. (2000). The

Steady Stare dara colleered for different

orienearions of the hearer and cooler are plotted

without and with consideration of loeal pressure

losses in Figs. 5a and b respecrively. The

experimenral dara is observed to he very dose tothe thenrerieal correlations for all orienrarions of

the heater and cooler confirming the validiry of

the correlations (15) and (16). Considering the

loeal pressure loss,,", improves the agreement with

the thenrerieal correlarions (see Fig. 5b).

Expansion tank

301<

73>Heote<

300

,107--

+'

m

----

-

"40Heat..-

Fig.4. Exprimmtallo'ptMudyth"ffi,"j'rimtati..,jth,he",".",.ndh""ink (aildim,mi,minmm)

"u

133 r

1C(,0' "'.IN. 10'

,." ,."

Fig.5. Eff",of"'",",nd",o"'o"m.."o",..",Rdy""'jIow

Subsequent to this, experimentS were carried our

in the high pressure nonuniform diameter figure-

of -eight loop FlSBE (Facility for the Integral

System Behaviour ExpetimentS, see Fig.G), whichsimulares rhe Narcra Atomic Power Station.

F;g. 6. Seh,maNe dia8mm afF/SSE

Steady State dara from FISBE are compared with

the present correlation in Fig. 7, which shows

good agreement. It may be noted thar for these

'" ..'" "'""",,'" .. .".

Fig.7. Comp."'i.. orFISBEdAta with th, th,"'ti"l"",fati..

testS the loop was an all pipe loop with a tubular

heater $Ccnon, a single V-tube Steam geeerator

and pumps replaced by pipe sections. Since rhe

I 34,-r-

SG used only one V-tube, more than 95% of the

loop hydraulie resistance was dne ro rbis.Alrhough rhe loop had several elbows, bends,Tees and orher fittings, rhese wen: mainlyconcentrated in rhe large diameter pipe sections.Hence the contribution of rhe local pressurelosses ro rhe roral hydraulic resistance became

negligible giving good agreement wirh rheturbulenr flowcorrelation.

Comparison with literature data

Several experimenrs on single-phase natural

circulation loops an: reponed in rhe lin:rature.

The loops studied can be categotised .. Unifonn

Diameter Loops (UDLs) and Nonunifonn

Diameter Loops (NDLs).

Uniform Diameter Loop, (UDLs)

The UDLs expetimentally srudied include borh

closed-loop and open-loop rhermosyphons.

Considering rhe shape of the loop, the closed

loops can be furrher classified into rectangul",

toroidal and figure-of-eight loops. Holman-

Boggs (1960), Huang-Zelaya (1988), Misale et

al. (1991), Bernier-Baliga (1992), Vijaran er al.

(1992), Ho e< al. (1997) and Nishihara (1997)

obrained experimental narural circularion data in

UDLs of rectangular shape. Uniform diaroeter

open-loops were invesrigared by Bau.Torrance

(1981, 1981a) and Haware er al. (1983).

Fig. 8 shows a compatison of the dara with rhetheoreticalcorrelationsfor laminar and turbulenr

flow for uniform diameter loops. The

experimental data reported by Misale et al.(1991), Bernier-Baliga (1992) and Ho et al.(1997) an: well predicted by rhe rheon:ticalconelation. Mosr of rhese data pain" an: fromlamin" flow region where rhe total local losscoefficientis negligiblecompared to LiD due rothe large value of the fricdon factor. For rherange 2xl0' <Gr.D/L,<3xlO' significanrdeviation

is observed be<ween rhe data and rhe correlation.

Beyond Gr.D/L, of 3x10', rhe agreement isfound ro be better.

,0' ,0' ,," ,," ,,' '0' ,.. '0'Gr.DIl,

Fig. 8. Study na" """",d "",,!.tUm flow in UDLs without

"""""'ng woo Wsses

For all the sready Slate data reponed in Fig. 8, it

is assumed that ~l,..=l. Bur for all practical

configurations ofloops, locallosscs are present so

rhat ~I..,>l. Hence, rhe observed deviations wirh

rhe rheoretical condation may be antibuted

pardy to rhe unaccounted local pressure losses in

these loops. To srudy irs effect, rhe local pressureloss coefficients due to elbows, bends, Tees,

orifices, etc. given in Streeter and Wylie (1983)

were used. The resulrs are shown in Fig. 9. Theturbulent flow data is now closer to rhe

rheore<ical cortelation indicating rhe significance

of the local pressure losses at high Reynolds

numbers where the friction factor is very low.

The laminar region data is practically unaffected.

The data for the transition region

2xlO' <Gr./NG<3xlO' is now closer to rherheomical correlation, but rhe deviation is srill

significant. This is the region where the

correlation is not applicable.. the loop is neither

fully laminar nor fUlly turbulent. Insread rhe

I 35 I--

loop is partly in the laminat tegion and pattly in

eithet ttanSition Ot tud",lent regions.

,~

l.'

".~"/1~.rf'~I""'~IO'IO"IO'IO'IO'IO'1

i, ll~1

F;g.9. S"ady"'" ",,"ml ,;",lat;,. J"'w ;n UDw withjqcaljq"N

Nonuniform Diamet" Loop' (NDLs)

Most pracrieal applications of natural circulation

employ non-uniform diameter loops. Common

examples", the nucbr reactor loop, solar watet

heater, etc. Most test facilities simulating nuclear

reactOr loops also use non-unifotm diameter

loops. Depending on the opera,;ng pressrne, the

non-uniform diametet loops can he catego,;sed

as High pressure loops and Low pressure loops.

Most studies "e conducted in the high-pressure

test facilities simulating nuclcat «actOt loops.

Typical examples ate the SEMISCALE, LOBI,

PKL, BETHSY, ROSA, RD-14, FISBE, etC.

Some studies, howcvCt, are carried out in low-

p«ssute facili,;es. Examples are the experiments

carried out by Zvirin et al. (1981), Jeuck et al.

(1981), Hallinan-Viskanta (1986), Vijayan

(1988) and John et at. (1991). Most of the

available expetimental da.. in a "",ble form (i.e.

full geomettieal details ate known) ate ftOm the

low-pressure test facilities. High-pressure test

data in a usable form was available only from

FlSBE. The data from NOLI are plotted in

Fig. 10, which shows reasonable agreement withmeoterieal correlation in the laminar and the

turbulent flow «gions. Significant deviation is

obsetYed fot the intermediate values of Gr.ING

where the flow is neither fully laminar nor fullyturbulent. Similar ttend was obsetYedinthe case

ofVDLI. Interestingly, the parallel channel da..

of John et at. (1991) and parallel loop data of

Jeuck C( at. (1981) are also found to he in

reasonable agreement with the theoreticalcorrelarion.~

,~I

,<I.

-~--......_----,... ,-.... ......................-...:=::=:;..-10"'" '" '" '" '" ~ ~

.......

F;g.lO.S"ad,"""J"'w;nNDww;th,.",mUknngiNaljq"N

..'

Stability behaviour

Experimental data on stability behaviour are few.

Even with the available data, it is often not

possible to accumely estimate the p...metetS

(see Eq. 21) affecting the stability behaviouL

This is often caused by the fact that the heat

transfCt coefficient V used in the St. is flow

dependent, which makes it difficult to estimate it

accumely. Due to this, the predicted stability

hehayjom is compared fot different loops to test

the validity of the scaling laws used. Figs, lla

and b show the predicted stability maps fot

laminar and trnbulent flow tespectively fm

different loops having the same length scale

mios, but with different diametetS. As expected,

the CUtVCSfot all the loops mCtgt giyjng a single

cutVe fot the stability behaviout. A predictionwas also made fot the different orientations

of the heater and cooler for the loop shown in

I 36 I--

-cIo6nmeMI nm

- d<!3.2nm0 I 0'

iI~...

..-.

.. t2 ...s.

s.(b) Turbulent flow.

(8) Laminar flow.

Fig. 11. S"bility map [0, wap"f diif,"nt diam"',

800

2 4 6 8S\"

10 12 14 16

1000

-' 600SJ<~\2. 400

200

00

Fig, /2. Effect of heat" and coo/" o,ientalio", on the "ability map

I 37 J---

Fig. 4. The results are given in Fig. 12. As

expected the results are found to be different for

the diffetent orientations, as the length scales are

different even though the total circulacion length

and diameter are the same. This emphasizes the

fact that simulation of the Stability behaviour

requires preservation of the length scales in

addition to the physical parametets of St., Gr.

and NG. This is because the feedback effects are a

Sttong function of the residena: rime, whieh

depends on the length scale.

Conclusions

Scaling laws for single-phase natural circulation

systems have been presented. For single-phase

systems, the Steady State behaviour can be

simulated by preserving Gr.lNG same in the

model and prototype. For the stability behaviour,

scaling of the characteristic equation (obtained

by the linear Stability analysis method) appears to

be the appropriate method for achieving

similarity. This requires simulation of at least

three dimensionless parameters in addition to

geometric scaling for single-phase loops.

Simulation of the stability behaviour of uniform

diameter loops requires preservacion of the

length scales in the model and prototype in

addition to the similarity parameters appearing

in the nondimensional governing equations.

Nomenclature

A - flow area, m'

- dimensionless flow area, NA,

-constant in equacion (9)

-specificheat,J/kgK

- hydraulic diameter, m

- dimensionless hydraulic diameter

- Darcy-Weisbaeh friction facror

-gravitational acceleracion, mls'

- modified Grashofnumber,

D:p,'~gdThl'

b

CpDdf

gGr.

HkKILN

NG

-loophcigbt, m

- thermal conductivity, W/mK

- local pressure loss coefficient

- dimensionless length, UL,

-length, m

- total number of pipe segments

-dimensionless parameter defined

by Eq. (11)- Nusselt number, UD/k

- constant in Eq. (9)

- perimeter, m

Nu

pp

Pr - Prandcl number, Cp"'k

-heat flux, W/m'

- total heat input rate, W

- Reynolds number, DW/Aj.1

- co-ordinate around the loop, m- dimensionless co-ordinate around the

loop, slL,- modified Stanton number

qQRe

St.-time,s

T - temperature, K

"'T, - referena: temperature differena: in Gr.

defined as (QH/A,j.1Cp)U 0 heat transfercoefficient,W/m'K

V, -total loop volume, m'W 0 massflow rate, kgIs

, elevation, m

Z -dimensionless elevarion (z/H) or (zI"'z)

t.z - a:nrre line elevation differena: betWeen

cooler and heater, m .

Greek Symbols

~j.1ep,

- thermal expansion coefficient, K'

- dynamic viscosity. Ns/m'

0 dimensionless temperature

-referena: density, kgIm'

-dimensionless time

-dimensionless mass flow rateco

J38r-

Subscripts

d- cooler

- cold leg- equivalenr- effective- heater

effhhi - hot leg

- ith segment- pipe- reference value

- secondary

References

I. Bade, M.H" Development of generaJised

correlac;on for steady state behaviour of

single-phase natural circulation loops and

investigations on the suppression of

instability using helica1 wire inserrs, M.E.

Thesis, Shivaji Universiry, Sangli,

Maharashrra, India.

2. Bau, H.H. and Torrance, KE, Int. J. HeatMass Transfer 24 (1981) 597-609.

3. Bernier, M.A. and Baliga,B.R, Int. J. HeatMassTransfer 35 (1992) 2969-2982.

4. Cteveling,H.F. De Paz,J.Y. Baladiand R.J.Schoenhals, J. Fluid Mech. 67 (1975) 65-84.

5. Hallinan, KP. and Viskanta, R. HeatTransfer from a rod bundle under natural

circulationconditions, NUREG/CR-4556.

Haware, S.K Grover, RB. and Venkat Raj,V. HMT-D2-83, Proc. VIIth National Heatand Mass Transfer Conference, Indian

Institute of Technology, Kharagpur, India,1983.

7. Heisler, M.P, Nucl. Sci. Eng. 80 (1982)347-359.

6.

8. Ho, C.J, Chiou, S.P. and Hu, c.S, Int. J.Heat Mass Transfer, Vol. 40 (1997) 3553-

3558.

9. Holman J.P and Boggs, J.H, J. HeatTransfer 82 (1960) 221-226.

10. Huang, B.J. and R Zelaya, J. Heat Transfer

110(1988)487-493.

11. Ishii,M. andKataoka,I.Nud. Eng. Des. 81

(1984) 411-425.

12. John, B. and Kannan Iyer, Proceedings of24'" National Fluid Mechanics Conference,

1991.

13. Jeuck III, p" Lennerr and Kiang, RL, Rep.EPRI-NP-2006,1981.

14. Misale, M. Tagliafico, L. and Tanda, G.

Proceedings of the fourth InternationaJSymposium on Transporr phenomena inheat and mass rransfer, Sydney, 14-19 July

(1991) p.203-21 I.

15. Nabavandi, A.N, Castellana, F.S and

Moradkhanian, E.N, Nud. Sci. Eng.72(1979) 75-83.

16. Nayak A.K, Vijayan P.K, Saba D., VenkatRaj V, Adtomi M, J. Nudear Science andTechnology, 35, 712-722,1998.

17. Nishihara, T., Proceedings of NURETH-8,

Kyoto, Sept. 30-0ct. 4. (1997) 839-847.

18. Streeter, V.L and Wylie. E.B, 1983 FluidMechanics, p.243-45. McGraw-Hill BookCompany, Singapore.

19. Vijayan, P.K. Investigations on the single-

phase thermosyphon phenomenon in afigure-of-eight loop relevant to pressurisedheavy water reactors, Ph. D. thesis, IndianInstitute of Technology. Bombay.1988.

20. Vijayan P.K. Bade. M.H. Saba. D. Sinha.R.K and Venkat Raj. V. A generaJizedcorrelation for the steadystate flowin single-

139 I-

phase natural circulation loops, BARCteport, June 2000.

21. Vijayan, P.K, Nayak, A.K, Pilkhwal, D.S,Saha, D. and Venkat Raj, V, NURETH-5,Salt LakeCity, UT, VoL!, (1992) 261-267.

22. Vijayan, P.K. and Ausrregesilo,H, NuclearEngineering and Design 152 (1994) 331-347.

23. Vijayan, P.K, Invited talk, M. Misale andF.Mayinger, (Eds.) 3-16, 1999, Proceedingsof EUROTHERM SEMINAR No. 63 on

Single and Two-Phase Natural Circulation,6-8 September 1999, Genoa, Italy.

24. Zvitin, ¥. Jeuck III P, Sullivan, c.W,Duffey, R.B, J. Heat Transfet 103,(1981)645-652.

25. Zuber, N, Ptoblems in modelling of smallbreak LOCA, Rep. NUREG-0724;-Ocrober1980.

About th.author. ...

Dr. P.K Vijayan join.d th. 2rf batCh of BARC Teaining School ofi" g>'aduatingin chemicalmginmingJiom th. Univmity ofCalieut. Dr Vijayan obtain.d his Ph.D. from 1.1 T. BombayfirhiJ work on natural circulation in a figu,,-of.ight loop "I.vant to PHWJcr. He has work.d inGRS, Munich, for a ym on th. simulation of natural circulation systems. H. has mablish.dhi"".1f as an "'pm in th. 0"0 of nuclear ",mor thmnalhydraulics. Dr Vijayan) work on singl..phas. natural circulation loops iJftoqumtly citd by rmarchm as a significant contribution. HiJeumnt rmarch intmsts includ. stability of two-ph.,. natueal circulation, staling of nuclear"actor syste"" aad "'ting up of th"malhydraulic test faciliti" "lated to th. Advan"d HeavyWater Reactor aad th. P",suriJ.d Heavy Water Reacto".

. . .I 40 I--

BIOREACTOR TECHNOLOGYFOR LARGE

SCALE CULTIVATION OF PLANT CELLSUSPENSION CULTURES AND PRODUCTION

OF BIOACTIVE COMPOUNDS

Dr. Devanand P. Fulzele

Nuclear Agricuttura and Biotechnology Division

Bhabha Atomic Research Centre

Abstract

A bioreactor with helix impellerhas beendesignedand developedat Nuclear AgricultureandBiotechnology Division capable of growing high density plant cell suspension cultures. The design

of this bioreactor has been transferred to Kabra Drugs Limited, Indore under a technology

transfer agreement. Mixing studies revealed that the helix impeller speeds of 80 rpm to 200 rpm

ensured uniform mixing of swpension cultures. Calharanthw resew cell cultures cultivated in

100 lit bioreactor with an initial 1/,5% packed cell volume to give an initial biomass to liquid

ratio 42.6 gr' fresh biomass at Kabra Drugs Limited, Indore. This resulted in production of a

biomass 32 Kgfresh weight within 16 days of cultivation, whereas natural grown plant produced

2.3 Kg/m'/year. This work addressed the destgn and development of helix impeller for 50 and 100

lit bioreactor for high density Calharanthw rosew cell swpension cultures.

MEDICINAL PlANTS ARE THE

most exclusive source of life saving

drugs for the majority of the world's

population. About 8000 herbal temedies have

been codified in the Ayurveda, which is still in

use in many areas today and large numbers of

bioactive compounds ate life saving drugs [1].

Bioactive compounds currently extracted from

plants ace used as food additives, pigments, dyes,

fine chemicals, insecticides, cosmetics and

perfumes. In view of the growing world

population, increasing anthropogenic activities

and rapidly eroding natura! ecosystems, the

natural habitats for a large number of plants are

rapidly dwindling leading to extinction many

valuable species. One alternative is to culture

plant cells in bioreactor under controUed defioed

parameters retaining the biosynthetic capacity to

synthesise bioactive compounds. A number of

plants such as Catharanthw roseu.>(vincristine,

vinblastine, ajmalicine), Taxus baecata (taxol).

Nothapodyur fodida (camptothecin), and

Artemisia annuo (anemisinin) have been

screened for ami-cancer, anri-AIDS, anti-

malacial and other useful bioactive compounds

for therapeutic use [2-4J,

India is a rich SOutce of medicinal plants.Aromatics, essential oils and bioarove

compounds bearing plant constitute an

important group of the India flora. Today, one

quarter of all ptescribed medicines used in the

I 41 I--

USA is of the plant origin [5]. Currently,

pharmacourical companies are manufacturing

most of rhese compounds by cultivation of

whole plants followed by extraction and

purification of the desired bioactive compounds.

The continuous production of the desired

bioactive compounds requires repeated collection

of plant material and consequently this leads to

the serious problem of depletion of natural

sources. Secondly, plants are not often readily

available. Mass cultivation of medicinal plant

species under natural conditions may not be

possible due to environmental, ecological, or

variable climatic conditions, length of

propagation or the noed to use agricultural land

to ptoduco the primary food crops. Quality and

quantity of the products is also effected byunforoscen environmental conditions.

F;g.I.Ma"p"pagariaaafmul<;pkrha",rol,"",af

A,trm;;;a aanua

Bioreactor

Biureactors provide nurritional and closely

conrrolled environment for optimum growth of

plant coils in which cells perform biochemical

rransformation to synthesise bioactive

compounds. Bioreacturs have sevoral advantages

for mass cultivation of plant cells. i) it gives

borrer conrrol for scale up of cell suspension

cultures under defined patameters for the

production of bioactive compounds. ii) constant

regulation of conditions at vatious stages of

bioreactor operation is possible iii) handling of

culture such as inoculation or harveSt is casy and

saves time Iv) nurrient uptake is enhanced by

submerged culture conditions which Stimulate

multiplication rate and higher yield of bioactive

compounds. v) large number of plantlers are

easily produced and can be scaled-up.

ng.2. Scak-up afCarhacauthm"'rm "u rot,""';n a20{;t"a;r

J 42 I--

Bioreactor Designed and Demonstrated

for Cell and Organ Cultures

Bell-jac biNeactors designed in Nuclear

Agriculrure and Biorechnology Division for mass

peapagation of cell and organ culmres. This

bioreactor demonsrrared rhac large-scale

cultivation of multiple shoots and planrler

cultures can result in production of plant

secondary produ", ac levels higher than rhose of

whole plants The newly designed bio;eactor

pmved that any mulriple shoor and planrler

culmres could be mass propagared under defined

controlled parameters (Fig. 1). Cell cultures of

Cathaconthus roseus were performed in a 20 lir air

lifr bioreaeror for pmduerion of aimalicine

(Fig 2).

The application of bio;eacmr system for lacge

scale cultivation of plant cells for rhe pmduerion

of valuable bioaerive compounds is an acrive

field, whose application holds great pmmise for

pharmaceurical industry. Large scale cultivation

of planr cells in biorcaeror increases rhe biomass

production much more than rhe whole plants are

gmwn in rhe field. Culmre cycles of cell

suspensions in bioreactor would be a question of

weeks and not of years as for oxample in case of

shikonin plant, which usually is not harvested

befo;e the age of five years. Successful

producrion of shikonin in bioreaeror by cell

culrures of Lithospermum erythcorhizon which

was the first commercial process using plant cell

cultures [6]. The commercial exploitarion of

bioreaeror rechnology is an alternative and

attractive area for bulk pmduerion of bioaerive

compounds for rherapeutic use.

Plant cells in liquid suspensions offer a unique

combination of physical and biological

propenies rhat must be accommodated in large

scale bioreaeror process aimed at exploiting rheir

biomass and synthesis of bioaerive compounds.

Some of the well-known drawbacks of the cell

suspension culmres in bloreacmr includes the

instabiliry of the productive cell lines, the

slowness of the cell growth and pmduerion phase

and limited knowledge abour the secondary

metabolite pathways [7]. There are indications

that sufficient oxygen supply and proper mixing

in air lift bioreaerors may not be suitable for high

densiry (2:300 ro 350 g/l fresh biomass) plant cell

suspension culmres. Secondly, the pmblem of

well-known shear sensitivity and rapid setting

characteristics of plant cell aggregates and cell

floating tendencies of the cell culmres have ro be

solved when bioreaerors for plant cell cultures ace

designed [8].

Plant cells are 10 to 100 times larger than

bacterial and fungal cells. Cultured plant cells

range fmm 20-40 ~m in diameter and from 100-

200 ~m in length and embrace vacuoles up to

95% or more of cell volume. These features have

led ro the belief that plant cells are shear

sensitive. Also, the oxygen requirement of plant

cells is low in comparison to the oxygen

requirement of micmbial cells. Such special

feamres of culmred plant cells necessitate ro

design and develop a impellet for bioreacror,

which could pmvide prope; mixing and

sufficient oxygen supply thmughout the

bioreaeror without forming dead zones and will

nor damage the cells during cultivation period.

The hydrodynamic conditions in bioreaerors are

most strongly dependent on the impeller design.

In view of this imponaor point, a helix impeller

was designed and developed fot 50 and 100 litbioreaerors and Catharanthus roseus culmres were

successfully grown at high density (Fig. 3).

Bioreaerors (50 and 100 lit capacity) were also

designed with several options to perform

continuous, semi-continuous, single and double

Stage operation modes with plant cell cultures.

J 43 I--

The geomet'}' of the helix impeller cesulred in

upward liquid pumping" the blades uponcoumer clockwise rotation. Bioreacror with helix

impeller decrea.ses the borrom and top conical

slower mixing zones generated by other types of

the impellers. Agirarion speeds ranging from 80

rpm to 200 rpm also improved mixing efficiency

of cell suspension cultures. Large scale cultivationof Catharanthu; meus cell cultures ha.s showed

rhat the bioreacror configurations with helix

impeller did not yield slower mixing zones of the

impeller" speed ranging from 80 rpm and

above. Impeller speed lower than 80 rpm

resulted in serring of cell aggcegates suspension.

The viscouj- shear-thinning behaviour of cell

cultures, whose homogenous mixing at low shear

and proper oxygenarion are problematic using

convention'! or pneumatic agitation sysrem for

biareactars [9J.

Bioreacror rechnology was rransferred to Mis.

Kabra Drugs Limited, Indore, a pharmaceutical

based company for large scale cultiv"ion of plam

cell culruces and production of bioacrive

compounds (Fig. 4). Biarcacror-grown

suspension culrures in 50 and 100 I bioceacrors

were highly homogenous in overall appearance

and compared well ra rhose with cultuced in

shake flasks. Microscopic observations revealed

that borh bioreacror and flask grown sospensions

comprised of single cells.

Cell cultuce experimems confirmed rhar rhe

biareacrors (50 and 100 I capaciry) equipped

J 44 I--

with helix impellet is suitable for growing low ro

high density cell suspensions. The most wuhed

mixing speed was observed at 140 tpm, which

was nor related to cell lysis bur to excessive

vonexing of the suspension and biomass

pwduction at highet speed.

Mass Propagation of Catharanthusroseus in 100 lit Bioreactor

Latge scale cultivation of Catharanthus roseus cell

suspension cuhures wece pdormed in 100 I

bioteactor (wotking capacity 75 I) equipped with

helix impelleL Cell suspensions wece established

in Murashige and Skoog's medium

supplemented with 2,4-dichlmophenoxy acetic

acid (9.05 ~M) and kinetin (4.65 ~M). Basal

medium was pcepated in rap watec and m"ket

SUpt ro teduce the pwduction costs of biomass

and bioactive compounds. Two week old

suspension cultmes wete used as inoculum giving

an initial biomass ro liquid tatio of 42.6 g I'

fresh biomass. The speed of the helix impellet at

140 rpm and initial dissolved oxygen (pO,) was

maintained at 30%. Cell culrures showed

uniform growth over a period of 15 days and

than reached to stationary phase. Sucrose in the

medium was completely hydrolysed within cwo

days, and the monosaccharides were consumed

thereafter by the cells. The final yield of biomass

was 32 Kg fresh weight in 16 days of cuhivationin bioceacroL It was shown thar the 100 lit

bioreacror displayed good performance in

growing high density Cathamnthus >OSfUScell

suspension cultures (Fig. 5). The higher and

more efficient upward suspension pumping

capacity at low sheat tate of the helix impellet,

ensured sufficient and more uniform mixing of

the delicate plant cell suspension and their berrer

growth performance. This resuhs demonstrated

that large scale cuhivation of plant cell cuhures

in bioreactot equipped with helix impeller is a

viable technology for phatmaceurical industries.

~~'"[

~-~~,=~~,~~: "

//"? ",c~

-', / /___fc-:::.:.:~>L~~~ ",-,

"

..,~,~,~'"

, nm."',,'"

The design of the helix impellet and its

mechanical feasibility and the mechanical sterile

seals teptesem key components of successful

biorescroL The industrial use of this type of

biorescror configuration depends on the low

sheat mixing efficiency and dissolved oxygen

(pO,) supply.

Many multinational pharmaceutical companies

have starred their production unirs in India with

a view ro produce bulk amounts of plant based

drugs. Currently, pharmaceutical companies are

using field grown plants followed by extraction

and purification process to achieve the fine

powder containing bioactive compounds. The

continuous production of ami-cancet, ami-AIDS

and othet imponam life saving drugs requires

large number of narural grown plants. Thetefore,

pharmaceutical companies ate cutting plants

from the fotest. It causes the setious problem of

depletion of narutal sources and disappeated

sevetal elite varieties of the medicinal planrs. It is

the right time ro take the opponuniry to develop

eco-ftiendly indigenous bioreacror technology

J 45 I--

for large =Ie commercial producrion ofbioactive compounds and to protect the naturalsour«,;.

Acknowledgement

I would wish to thank Dr. (Ms.) Susan Eapen.

Head. Plant Biotechnology and Secondary

Product Section, Dr. R. K. Mitra. Head. Nuclear

Agriculture and Biotechnology Division. and

Dr (Smt) A.M. Samuel. Director. Biomedical

Group. for their constant encouragement.

References

I. Haung PL, Huang HI & Lee-Huang S.(1992) Developing drugs form traditional

medicinal plantS. Chemimy and Industry.

April. 290-2932. FulzeleDP & Heble MR. (1994) Largescale

ccltivation of Catharanthus mew cell"

ProduCtion of ajmalicine in a 20-1 airliftbioreaeror. Journal of Biotechnology; 35:1-7

3. Fetr-Nero AG, DiCosmo F, Reynolds WE& Sakata K. (1992) Cell culture of Taxusas

a sourceof the antineoplasticdrug taxoIand

related taxanes. Biorrechnology; 10:1527-1575 -,- --~,

4. Fulzele DP. Heble MR & Rao PS. (1995)

ProduCtion of terpenoid from ,!rtemisia

annua L. pianrier cultures in bioreaeror.Journal of Biotechnology; 40: 139-143

5. Farnsworth NR. (1985) The role of

medicinal plants in plantS in drugdeve10pmem. In: Kroogsgard-Latsen P.

Brogger Christensen S & Koford H (cds).Natural ProductS and Drug Development

(pp 17-30) Munksgaard Copenhagen.Denmark

6. Fujita Y. Tabata M, Nishi A & YamadaY.(1982) New medium and production of

secondary compounds with the tWOstage

culture method. In: Fujiwara (ed) Proc. 5'Inri. Cong, Plant Tissue and Cell Cultures

(pp. 399-400) Maruzen Co. Tokyo7. Panda AK, Misra S, Bisotia VS & Bhojwani

SS. (1989) Plant cell reactors-A perspective.

Enzy.Microbial. Technology; I I: 386-397

8. Tanaka H. (1987) Largescale cultivationofplant cells at high density. Proc. Biochem.

August. 106-1109. Tanaka H. (1982) Oxygen transfer in brorh

of plant cells at high density. Biotchno!.

Bioeng. 24: 425-435

rn:::"D'ev;;;;;'ndP. Fulzele is the recipient of the BARC Thch;;;;;;-;;;eiknce Award

..!::r!::.!.::.rIf!!!-- - - - -- - '-~-Abouttheautbor..."

- ~~ =sF'~~'C".~-

Aft" obtaining his MSc. degreein Micwbiology from Nagpnr University. in 1982. Dr Droanand

P. Pukek joined N""kar Agriculeure and Biotechnology Divuion. BARC. in 1986. Since thm. he

hm bem working in the area of bioreactor 'Y't<m jOr large "ale cultivation of plam cel/ culeu", and

pwduchon ofbioactior compounds, [), Fukek obtained hu Ph.D. degree in 1996 from Mumbai

Univmity jOr his work on regulataory asp"" of secondary metabolism in mdidnal plant tusue

culeu"" Hu primary cantributiom are the dnign and ",",Iopmmt of bioreacton jOr organ and cel/

cultu'" jOr pwduct 'Y"th"u. Hu work als" ioclud« dnigu and ",",Iopmmt ofbioreacton at commercial kvrb.

. 0 ... 0 .

I 46 I--

GAS DETECTORS FOR HEAVYION EXPERIMENTAL NUCLEAR

PHYSICS RESEARCH

D. C. Biswas and R. K. ChoudhuryNuclear Physics Division

Bhabha Atomic Research Centre

Introduction

GAS DETECTORS HAVE PLAYED

an imponant role in nudear phy,ics

experiment> since many decades. With

the advent of high energy heavy ion

acceleratot>. there has been a growing need ro

develop differen, <ypes of gas de,ec<ors ro mee'

various experimental 'equirement>. Gas detec<ors

offer several advantages in comparison to other

types of nudear radiation derecto". such"

va"atility in construction with regard to size and

shape. variety in the mode of operation.

uniformity of detec<or thickn=. flexibility in

detec<or thickness variation by adjustment of

gas pressure. immunity to radiation damage.

good timing and pulse beighr charac<eristicsand ease of fabrication etc. Because of the above

advantages, various types of g" detec<o" are

extensivdy being used as ionisarion chambe",

proponional counters and avalanche derectors

for heavy ion reaction studies. Today. most of

the detectors used for tracking and imaging in

high energy physics experimenrs are based on gas

detec<ors. The use of gas detectors has also spread

to many different fields of applied research, such

as X-ray and heavy ion astronomy, nudear

medieine and protein ctystallography etc.

An energetic charged nuclear partide traversing

in a gas medium interact> with the aroms of the

medium in many ways. Of all possible

inreractions. the electromagneric' interac<ion is

generally many ordet> of magnitude more

probable than rhe strong or weak interacrions.

and takes place by the incoherent Coulomb

interacrions between the electromagnetic fields

of the incoming charged panide and of rhe

medium. produeing both exeitation andionization of the aroms of the medium. For

heavy ions of energies ~l MeV/u and above. the

energy loss is predominandy due to the inelasticcolli,ion of the ion with the medium electrons.

However, at lower energies elastic collisions ofrhe ion with rhe medium nudeus becomes

imponant. These interacrions leave a trail of

elemons and ions in ,he medium. which are

collected by applying suitable eleCtric field to

produce an elemic signal.

Gas Jonisadon Chamber Detectors

Gas ionisarion chambet> are largely used for

charged panide spectroscopy studies where

identification of the panide is done by

measurement of energy loss (t.E) of an ion in a

rhin transmission type detecror together with

the residual energy (E,) by anothet detector.

Such an arrangement is commonly known as a

detector telescope. The parride identificarion is

based on the <quarion for rhe rate of energy loss

[IJ.

t.E( E, + t.E)-KMZ'", (1)

I 47 /--

where, K is a consranr, M is rhe mass and Z"

is the effecrive charge of rhe ion. For energetic

light charged parricles, Z", = Z, whereas, for

heavy ions Z", less dun or equal ro Z and

depends on the energy of rhe ion. For fission

fragmenr;, rhe effecrive charge Z is expressed as

Z," = yZ. Here y is the effecrive charge panmerer

and has a complicated dependence on the

aromic number Z and energy of the fragmenr'

[2J.

In case uf heavy ions of low energy, one

requires a thin and uniform transmission rype

liE detector for carrying out parricle

idenrification. For ions of Z= 10-40, ar energies

less than 2-3 McV/u, it is dcsirable ro have very

rhin (1-4 ~m cquivalenr Si thickness) detectors.

With the correnr technology it is very

difficult to produce uniform Si detecrors in this

range of rhickncss. The much grearer uniformiry

of a thin gas transmission detector gives it an

advanragc over silicon detecrms. Diffcrenr

rypes of derceror tebcopes Imed on IIE~,-IIE"

and have been developed

and used us for measuring rhe energy,

charge and mass of charged parricles and fission

fragmenrs produced in heavy ion induced

reactions at the pelletron accdetatm, Mumbai.

Hybrid dE",-£" detector telmope

The hybrid telcscope which is developed [3J for

heavy ion experimenrs, consist> of a g"

ionisation chamber for me"uring liE and a

surface barrier detector ro mmore the

residual energy loss (E,). These derecrors are

eommonly used for idenrificarion of heavy ion

""ion products to measure their energy, chargeand mass. These derecrors are also suitable

fm fission fragmenr measuremenr providing

good separarion between projectile like

parricles and fission fragmenrs. The schematic

diagram of rhe hybdd detector rebcope

developed ar BARC, is shown in Fig. I.

'iJ '

S.B.DeItCIIII

Fig! Schematic diagmm 'fhyb,id "u,wpc

It consisrs of a gas ioni,arion chamber (10 cm

length) having a grid and a collector parallel tothe ion track and a surface bOHier detectot

(rypically 500 ~m rhickness) ar rhe end inside

the gas medium. The main body of the derectoris machined from srainless sreel marerial and

acts as carhode. The Frisch grid is conmucted

by fixing a metallic mesh (95% transmission) on

a recrangular frame made ~Ut of Cu-plated

fibre glass. The anode plate is made of one

sided Cu-plared fibre glass. The separation

between the carhode and grid is 40 mm and

grid ro anode is 10 mm. The detector works in

ionisarion region so rhar rhe pulse height is

proporrional ro primary ionisarion in rhe g"medium. A collimaror of 5 mm diameter is

mounred in fronr of the detecror and a thin

( 1-2 ~m ) polypropylene foil is placed as the

window ro allow rhe reaction producrs enrer intorhe derector. This detector has been used for

measuring fission fragmenr angular

disrribUtions [7] in heavy ion reacrions and

identification of projecrile-like fragmenrs (PLF's)

produced in heavy ion reacrions ar energies near

I 48 I--

(he Coulomh banie, [5,6]. The "E-E, plm

,hown in Fig. 2 demo""",e, the eb, ,ep"ationof va,iou, pmjwile-like fDgment' (Z=2 to 10)pmduced in "F+mTh "action at lO8MeV.

2561

~192 ,10:>~_"lF9

."<;. 8i<5128OJ<J

".

64

,"'Th,t 108M,V

01"'~~0 64 128 192

E"(Ch"",,,IN,)256

Fig.2 &-E.pl"fi"""wmPL6pmd",,dinnF/'~Th>,"cticmae]()8MeV

Multi-angle Hybrid (LJE",-E) deteCtor tele;cope

A multi-angk particle tebeupe having

common "E,,', backed by th,ee ,ilicon E

detecto" at 9' intecvab 1", been developed

and it', p,inciple of ope,ation i, >ame a' the

hyb,id detecto, telmope mentioned above.

Thi, detectoC i, 'pecifi"lIy u"ful to cany

out the angulo, distribution of fi"ion fDgment'

and heavy ioo>. U,ing this detecto',measueement> have been canied oue on fi"ion

f,agment angul" distribueioo> at nea, bani"

en"gie, [8J.

Poshion"nsitioe ionization chamber (M",-E~)tleteetor

A trapezoidal ,haped g" ionisation chamb" hasbeen developed [4] fa, heavy ion ceaetionstudies, which "n be used fo, particleidentific"ion fmm the "E-E info,mation and

the position mwueement is obtained by

dividing tbe "E anodc imo multiple "gmentsand employing ch"ge divi,ion technique. The

"E-part of the anode plate i, divided into five"gme<'" along the particle tDck and thealtem"e "gments ace connected togeth" fa,position dete,mination. With this detecto, one"n idemi£» the particle and simultaneouslymea,",e the en"gy " well "' angle of the

,eaction pmduw.

Fig. 3 &,.-E,. P"i,ian "n,iei" i,niw,i" ,hamha.

The main body of the detector as shown in

Fig.3, i, machined fwm ",inless steel material.

The detector assembly which consist, of a

cathode, a Frisch g,id and anode plate ("E path

Iength=45 mm and E=90 mm) all having

uapezoidal shape and mounted at suitable

"pararions with teflon wds and spacets, The

schematic diagcam of the detecwt ",sembly and

anode plate is shown in Fig. 4.

The "E, and "E, pulses are summed after

proper gain matching to obtain the total energy10" in the "E'section of the ionisation

chamber. The deteeror has been used in heavy

ion experiments fo, measuring fission fcagmentsin a number of heavy ion induced reactionstudies. The position in the reaction plane ismwllred by the chatge division method. The

"E anode segment is splitted into threesegments which are alternatively connected,so that the avecagedE/dx is almost equal in both

I 49 I--

-"'m.",

"'!I..-...~"'-

d"",", ""tmbly, and (b)

the 'egmem' fm the pacticles ente,ing alongthe cemeal line of the detecto', even fo, fi"ion

f,agmem, who,e 'pecific eneegy neie, mongly

along the ,ange[3]. Pacticles pa"ing at any

othee angle will lo,e eneegie, ptopoctional to

the path length, in LlE, and LlE, ,egmem,. A

po,ieion paeametee defined as x=( LlE,- LlE,)!

(LlE, + LlE,)i, ptopoctional to the panicle

po,ition and i, ,elated to the ,catteeing angle

of the pacticles in the "action pbne. The

po,ieion "wlution i, about 1.1 mm whicbteansbtes to 0.75' (FWHM) in the angle

",olution of the detectm which i, quite good

fo, studying the angula, dimibution of fi"ion

feagmenes in heaVy ion "aceions.

Fig. 5 ,how, a ,cactee plot of LlE, vs "'E, fm "'Cf

fi"ion feagmem, obtained fo, a mask having five

,lies each Imm wide and sepaeated by 5mm,

fixed infeom of the detectoe. Diffeeent band, ace

"en coctesponding to ,lit openings. Thc po,ition

'peceeum was obtained "pamcly fm the light

and heavy fi"ion feagment geoup' and i, shown

in Fig.6. In this geometry, the angula, cov""gc

of the deteceoe is 30' and the detecto, i, meful

fo, angular dimibueion studie,. In ,hi,

configueation of the anode pbtc, one can catry

out online calibmion of ,he po,ition ,ignal of

the detectm, which i, quite u"ful dueing the

expeeimems.

'I'

M;, (Chonn~1 no.)

'""'

Pig.5 JE,.JE,pl"J" "'CfJ»i'"ftagmmt> ",inga m"k withJ" ,/it>.

I 50 I--

Fig" Pai,,"" 'pwrnm fiN ligh' and hcany fmgman gmnp-

Fig] C" d"",," mmm"d imid, ,h, Hauaing ,hamba-

J 51 \--

Several experiments have been carried out using

this position sensitive ionization chamber in

combination with the hybrid detecror telescopes

mounted inside the general purpose scattering

chambers shown in Fig.7. Because of large solid

angle ( ~ 70 mSr ) coverage, this detector ismost suitable for low count coincidence

experiments and has been used for many heavy

ion induced experiments to measure the fission

fragments.

large solid angle coverage of about 50 mSr [9].

Fig.9 shows the schematic diagram of the

detecror assembly. Particle identification using

this detector is done by spliting the anode into

four regions, in which the reaction products lose

different amounts of energy depending upon

their charge and initial kinetic energy. To

measure the ma" of the reaction products, the

time of flight technique is employed making

use of the large flighrlength of about 1m from

Fig 8 La,gcA", P"iti" "",iti" la",wi" Chamba

Large Area Position Semitive lonisationChamber ( LAPSIC )

A large area position sensitive ionisation chamber

(lAPSIe) shown in Fig.S, has been developed .,

one of the experimental facilities for heavy ionreaction srudies. The main features of the

detector are wide dynamic range, good

charge and mass resolUtion, position

sensitivity borh in and out of reacrion plane and

the scatteting chamber to the enttance of the

ionisation chambo" The angular coverage in

the reaction plane is 22" and rhe position

measurement is carried out by using the delay

line method. The oUt of plane angle

information is obtained by measuring rhe drifttime of the elewons betWeen cathode and

anode. This derecror h., been used for

studying deep inelastic reactions and

I 52 I--

measmement of fission fragment energy" well

" time of flight in heavy ion induced reaerions

to ob"in the fi"ion fragment mass dimibutions.

A rypical tsE, vs tsE, plot is shown in Fig.IO

shows a clear sepmtion of fission fragments

from projectile.like fragments.

thin structure, these detectors have excellent

inh"ent discrimination for low atomic

numb" iom, ultra fast timing and very good

position resolution. The detector was tested with

fi"ion fragments and the position resolution

of 0.5 mm h" been obtained. For the target

""\1.~- r ,

~ o.-

Fig.9 Schcm"i,di,t",m'fLAPSICd""""",mbly.

Position Sensitive Mnltistep ParallelPlate Avalanche Connter

Large area position sensitive multistep avalanche

counters have been developed in collaboration

wich Saha Imtituteof Nuclear Physics, Calcutta

and used for detecting fi"ion fragments

produced in heavy ion induced reactions at

Pelletron accelerator facility, Mumbai. The

posicion information both in x and .rdirections are obtained by the delay line method.

Because of very low operating g" pressmes and

detector distance of about 15 em, the angularresolution is about 0.15'. A typical x position

spectrum obtained for fission fragmentsis shownin Fig.I I. The dips in the spectrum indicatethe positions of nylon support wires of 0.6 mmdiamet".

Ai; the angular resolution of these detectors is

excellent, two such detectors were used for

detecting the correlated fission fragments [10].

By employing the folding angle technique,

various experimentS have been carried out

to seperate the complete fusion and transfer

J 53 I--

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Fig,JOEnngy ',m i. ,h".<kk pIA'" ,howi.g "fa"";.. 'I pi,. frag""'.. from PLP;,

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Fig,IIP"i'i"'p"'~mft'"'Cfft,i"fragmm"m'aM,dby "alA.,h",."",

I 54 I-

induced fission events for srudying rhe

angular distribution of fission fragments at near

barrier and sub barrier energies.

USe of the Gas Detectors in Nuclear

Physics Experiments

All the gas detectOrs mentioned above are

extensively used in heavy ion experiments at

Pelletron accelerator faciliry. Mumbai and have

given significant boost ro gas derectOr

technology for nudear physics studies. The

importanr results obrained using rhese deteCtors

(i) M=urement of fission fragment energy.

charge and mass ro study rhe specific energy loss

behaviour of fission fragmenrs along rhe rtack[2.3J.

(ii) The angular distribution of projectile likepartides have been studied to understand therole of projecrile struCtUre in mulrinudeonrcansfer and. rheir importance in explainingslope anomaly". which was observed in rhesingle and mulri-nudeon transfer reaCtionprobabilities for many rarger-projeCtilesysrems[5,6].

(iii) Using rhe gas deteCtors. m=urements have

been cartied our on heavy ion induced fusion-fISSion and transfer induced fission reaction

studies. for explaining rhe observed anomalous

angular anisotropies for seveta! systems ar

energies around rhe Coulomb bartier [11-12]. It

is observed rhat rhe orienration dependent

quasifission model could explain rhe observed

anomalous peaklike structure in angular

anisotropies ar dcep sub-bartier energies [13J.

The measurements on fusion-fission and

transfet induced fission reactions have also

yielded many new results. which are of

fundamental importance for an undersranding

of rhe mecbam.m of mass, energy and angular

momenrum transfer in heavy ion induced

reactions leading to fission in heavy targer nudei.

These experiments, have provided important

information to understand rhe dynamics of rhe

fission process [14-16J.

Conclusions

Various gas detecrors have been developed over

more man a decade for rheir use in experimental

nudear physics at pelletron aceelecaror. \iumbai.

Using these detectors ir is possible to IT)easure the

energy. charge, mass and position informacion

which are very useful paramerers ro identify a

heavy charged partide. Several measurementshave been canied out to understand rhe

mulrinudeon ttaDsfer processes and dynamics of

heavy ion induced fusion-fission reactions.

Developments are still in progress to improvise

rhese detectors. design and fabrieation of new

ionisation chambers as well as cathode strip

detectors. Wirh rhe experience in gas detectors in

low energy nudear physics experiments,

collabotative experiments are also being cartied

out in intermediate nudear physics experiments

at LNL. Italy and in high energy physics

experiments using PHENIX detectot at BNL.USA.

Acknowledgement

The aurhors gratefully acknowledge Dr. S. S.

Kapoot for many illuminating discussions andsuggestionson rhis work. We are rhankful to Mr.

L. M. Pant. Mr. B. V. Dinesh. Dr. B. K Nayakand Dr. A. Saxena fot their involvementsduringthe various developments of rhe various gasdetectors.

References

1. F. S. Goulding and Bernard G. Harvey,Ann. Rev. Nucl. Sci.. 25.167 (1975).

I 55 I--

2. M.N. Rao, D.c. Biswas and RK.

Choudhmy, Nuel. Inm. and Merh. B51102(1990).

3. D.c. Biswas, M.N. Rao, and R.K.

Choudhury, Nuel. Inm. and Meth. B53251(1991).

4. D.C. Biswas, V.S. Ambeku, LM. Pant.

B.V. Dinesh and RK. Choudhury. Nud.Inm.and Meth. A34055I.(1994).

5. D. C. Biswas. R K. Choudhury. B. K.

Nayak, D. M. Nadkuni, and V. S.Ramammthy,Phys. Rev. C 56 1926(1997).

6. D.c. Biswas. R.K. Choudhury. D.M.Nadkarni. and V.S. Ramamutthy, Phys.Rev. C52 2827 (1995).

7. S. Kailas.A. Navin. A. Chatte*e, P. Singh.A. Saxena.D.M. Nadkuni, D.c. Biswas.

RK. Choudhury and 5.5. Kapoor, PramanaJ. Phys 41. 339 (1993).

.8. A. Kamik, S. Kailas,A. Chatterjee. P. Singh.A. Navin. D.c. Biswas.D.M. Nadkarni. A.

Shrivastavaand 5.5. Kapoor Z. Phys. A 351195 (1995).

9. Deep indasrie collisionsof "S+uAI reacrionat 130 MeV bombarding energy, R.K.Choudhury. D.M. Nadkuni, V.S. Ambeku.B.V. Dinesh, A. Saxena,M.S. Samant. D.c.

Biswas, and LM. Pant. Pramana. Vol 44.177(1995).

10. N. Majumdar. P. Basu, M.L Chatterjee..c. Biswas.A. Saxena. V.S. Ambeku. R.K.

Choudhury and D.M. Nadkarni. NuovoCimento, 18BA,(1995)817.

11. N. Majmudar. P. Bhattacharya. D.c.BiswasJ. RK. Choudhury. D.M. Nadkarniand A. Saxena, Phys. Rev. C51. 3109(1995).

12. N. Majumdar. P. Bhattacharya. D.c.Biswas,RK. Choudhury. D.M. Nadkarniand A. Saxena. Phys. Rev. C 53 R544(1996).

13. N. Majumdar. P. Bhattacharya. D. C.Biswas, R. K. Choudhury, D. M.

Nadkarni and Alok Saxena. Phys. Rev.Lett. 77. 25 (1996).

14. A. Chatterjee, A. Novin, S. Kailas.P.Singh. D.c. Biswas.A. Karnik. and S.S.Kapoor. Phys.Rev. C52 3167 (1995).

15. D.M. Nadkarni, A. Saxena. D.c. Biswas.

R.K. Choudhury. S. S. Kapoor, N.Majmudar. and P. BhattacharyaPhys. Rev.C59 R580 (1999).

16. D. C. Biswas,R. K. Choudhury, A. Saxena.D. M. Nadkarni and V. S. Ramamurtby.Submitted ro Phys.Rev. C (2000).

= -~-- "' ""'-- "". ~ it ,the !'!J.ipf,ent of the "S. N. Seshadri Memorial /nstrumentatWiig

-- - - .. ...1Abo.,th.A"""r....

Dr. D. C. Biswasjoin,d th, 21' batch of BARC Training School in J983 after obtaining M. Sc.dwr' in Physicsfrom Calcu'ta Univ"'ity. SinCt then. h, is working in Nuel", PhysicsDivision,BAR£. in variow rxpmmental acsiviM wing ,h, P,//rtron a",lvator fari/ity. H, is involved in,he drvr!.pmm' of variow gas d"",on fOr th,ir w, in h,avy ion indu«d nuclrar p""icsrxpmm'nff. H, has mad. significant contributions in "Multinuclcon transfer and heavy ioninduCtd fidon-Jission as w,1I as sequential fission reaction studies". H, has participated in severalinlrmational coDab"a""n rxpmmmu and has mad. impvrtant conmbu",,", in ,h, fi,/4 of

sprttroscoPJoffisswnfragmmu usingiawgammadrtrctor"..p (GASP }a, LNL./taly.

. . ..0. .

I 56 I--

SIMULATION AND EXPERIMENTALVERIFICATION OF HYPERFINE

SPECTRUM OF U-233

B.N.Jagalap, L.M.Ganlayel and A.P. MaralheLaser & Plasma Technology Division

S.A. Ahmad, A.Venugopalan and B.K.AnkushSpectroscopy Division

andA. Ramanujam

Process Development Division

Bhabha Atomic Research Centre

Abstract

Knowledge of hyperfine Structure (h],) OF lines of U-233 is of paramount importance in

configuring an isotope selective multi-step photoionisotion scheme for the clean-up process. Since

the isotope shift (IS) ov(233. 232) is small (ofew tens ofmil/ikayser). the spectral overlap between

U-232 and U-233 is governed by the hfs pattern of U-233. It is imperative that the spectral

transitions to be chosen for selective photoionisation muSt have smaller his extent to ensure high

selectivity in the Clean-up process. In thi.' paper. we present our theoretical and experimental work

on the his DfU-233. In whatfollows we discuss the hfs of5915A line [0 cm.IIL, -+ 16900 cm" oK,)

ofU-233 as a case study,

Theoretical

THE HFS OF AN ATOMIC LINE IS A

resulr of splitting of energy level caused

by the intemtion of the electron with

the nudeat magnetisation and nonsphetical

chatge distribution. The patamete" governing

the splitting are hfs constants A and B that

respectively signify the magnetic dipole and

electric quadrupole interactions. For the spectral

line under study the hfs constants ace repotted in

the literature for U-235 isotope [I]. This

information along with the nudeat patamete"

[2] (see Table-I) was used to construct the

constants A and B fat U-233 isotope and obtain

the splitting patterns of the lower and excited

levels. The intensities of the hfs components

were obtained using Racah algebta. The hfs line

spectrum thus obtained was broadened using

Doppler funcrion ro represent a bigh tesolution

spectrum obtained from a soUtce at a given

temperature. In Fig. I. we give the simulated

hfsspectrum of 5915 A line of U-233. We may

note here that since 11l"",1 > 11l"",I, the hfs of

U-233 has a widet width than that of U-235.

Furthetmore. the splitting pattern in U-233 is

regulat as against inverted in case ofU-235.

Table 1 : Nuclear Data for Uranium Isotopes

I 57 I-

Experimental

Fig. I. Simdaudhypafi"upmrnm'f59ISA'fU-233

GHz

The ,imul"ed 'pecrwm pwvide, "veralguideline, to obtain the 'pecrwm experimenrally.Specifically,a r"olurion of -10'i, mfficienrror"oIve rhe hf, " ,hown in Fig. L

Such re'Dlution i, convenienrly offered by

recording Fabl)'-Pewt optical 'pecrromerer

(REFPOS). To record a high r"olurion

'pecrwm of a line of an element on REFPOS, a

hollow cathode di,charge lamp (HCDL) i, u"d

" " muree of narrow atomic line" "peci']ly of

refracrol)' elemenr,. Umal HCDL, con,i" of a

cylindric,] hollow cathode, made up of elemenr

under invwigation in a gla" enclo,ure fitred

with optical window, and appropriate anode.

Thi, d"ign, alrhough convenienr for common

elemenr" i, nor ar ,]1 ,uirable for 'pecrw,"opy of

radioacrive elemen". The amount of meral med

for making a cylindrical hollow cathode i,

generally in rhe tange of 100-200 gm. Suchamoun" are pwhibitively large for radioactive

i,orope" and give ri" ro "vere radiologic,] "fety

pwblem,. In addition, the integrity of the enrire

HCDL a"embly i, qu"tionable owing to rhe

gla" enclomre

For the 'pecrro,"opy of U-233 (U-232 @ 2

ppm), we have developed a liquid nitrogen

cooled all mer,] HCDL which incorpora","ver,] novel idw and take infO comideration

pwblem, of handling rare and radioactive

elemen" [3]. Thi, new HCDL m" -10 mg of

U-233 oxide which I"" for about 50 hou" of

operation. The HCDL i, "urdy and inrrimically

,afe. In addition, it can be convenienrly loaded

with a radioactive mareri,] ",]ed hermetically in

I 58 I--

VALVE

PORT FOR EV ACUA TION& BUFFER GAS FILLING

QUARTZSPACER

METALO-RING

GLASS SEPARATOR

U-233 COMPOUND

COPPER CUVETTE

(CATHODE)

COPPER

Fig. 2. S,h,ma,;"u,ign ,fall m"al h","w wh,dofj"ha'g' lamp}>' high "wluti,u 'p""""'py'fV-233.

an a-protected facility and transported to an

inactive area housing spectroscopic instruments

S1lisfYing all the safety requirements. In' Fig. 2,

we show schematically rhe design of this new

HCDL. This HCDL, operated with neon as rhe

buffer gas, was used as a soum of U-233 atomic

lines. Tbe gamma radiation level was

continuously monitored all along rhe

specrroscopic experiment and was found to be at

the normal background level. The high

«solurion specrmm was recorded on

indigenously builr REFPOS. Fig. 3 shows a view

of REFPOS facility which consists of a high

resolmion monochromator, Fabry Peror

assembly and phoron counting system. All these

systems are fabricated and as>embled in BARe.

I 59 I-

Fig. 3. VI<w afREFPOS Fad!;ry. [<ft' En"'""'!;"fhlgh ,,;alutlan man"h"",,t" wl<h,k""". Rlgh" FabryP",t~"mbly with ,kt"'".

FIg. 4. Hft'p"""m af5915 A af U-233 ","..d<danREFPOS

I 60 f-

In Fig. 4, we show the experimental spectrum ofthe 5915 A line of U-233 as recorded on

REFPOS. This may be compared with the

simulated spectrum of Fig.!. The separations

and relative intensities of the hfs components are

in very close agreement in these two spectra.

In conclusion, we have demonstrated

experimentally the hyperfine specrrum of a lineof U-233 and verified the simulation of same

spectrum based on the knowledge of U-235.

These methodologies are useful in generating the

requisite database for the laser clean-up process.

Acknowledgement

Authots thank Dr. A.B. Patwardhan for Icnding

his experrise in handling and loading of U-233.

The alfa protected faciliry for Icak testing and gas

filling of HCDL, provided by Radiometallurgy

Division, BARC is gratefully acknowledged.

,This paper received the

",Thorium Fuel Cycle" in

1'2000) on "Power from'Mumbai, during June 1-2,

Abvut th, auth",..

References

1. W.J. Childs, O. Poulsen, LS. Goodman;

Opt. Lett., 4, 35 (1979).

2. V.S. Shirley and COW. Lederer, Tables ofNuclear Moments, Laurence Berkeley

Laborarory(1974).

3. S.G. Nalrhare, A.P. Marathe, B.K. Ankush,

A. Vcnugopalan, B.N. Jagatap, LM.Gantayet, S.A. Ahmad, U.K. Chatterjee,A.P. Roy, Proceedings of Seminar onSpcctroscopy,Lasetsand LaserApplications,(CUST, Kochi, March 23-26, 1998) p. 47.See alsop. 77 in thc samcvolume.

4. A.P. Marathe, B.K. Ankush, A.

Venugopalan, A.B. Patwardhan, B.N.Jagatap, A. Ramanujam, LM. Gan"ycr,S.A. Ahmad, Proceedings of Symposium onSpectroscopy of Lanthanides and Acrinides(BARC,Nov. 16-19, 1999) p. 109.

award in the category

Conftrence of Indian

Status, Strategies and

Technologies fOr

ar Society (INSAC-

ns ': held at BARC,

Dr B.N. Jagatap 17aduatd jrom th, 2(/" batch vi B/lRC Training Schoo! and vbtaind hi, Ph.D

(Ph]'i,,) Imm Univ",ity vi Mumbai in 1988. H, ha.<b"n a.<"ciatd with th, 1m"d;,ciplinaryCm", fir Ch,mira! Phy,i". Univ",ity vi W"'an Ontanv. Canada, a.<Pmt Dvctvra! h!/ow(1993-94) and Vi,iting Scimt;,t (1999 and 2000-2001).

Mr LM. Gantay", a ch,mira! mginm. jvind BARC in 1972. H, wa.<awa,d,d th, Hvmi Bhabha

pnu in th, 1971-72, 15" batch vi BARC Training Srh,"1 H, ha.<w"k,j fivm th, evn"pt tvdM/opmmt vi "'a! "rhnv!vKY vi th, ;,vtvp' "parativn pra""". H;, rumnt im""", indud<

dM/opmmt vi {",a-ba.<d "paradv" pra""".

J 61 I--

M, A,awa,i Ma,ath, i,ind th, 411'batch 'fth, BARC T,aining School afl" d,ing h" p"t p-aduati,n

in Phy,i,,;rom Indian In"itu" 'fT"hn,wgy, Mumbai.. Sh, i, "'mntly w"king in th, p"i"n if'

ClMn-up and £m" Cooling 'f Atom, in £m" &-P/a,ma T"hn,wgy Divi,i,n.

D, S.A. Ahmad, ft=,,1y H,ad, Atomi, Sp""""py St"i,n, "a"d hi, "imtiji' ,an" in 1962,whm h, i,in,d BARC fr,m th, thm Atomi, En,w T,aining School. H, ha; made vtry ,igniji,ant"nmbu",m to ,meal ana; in atomi, 'p""o"opy and;, India, I,ading 'p,dal;'t in ,tud;" nw"dto nutka, 4Ji'" in atomi, 'p""a. H, ha; m", than 70 publi,ati,m, m"tly in npu"d int".ational

iouma/i. D, Ahmad, during h;, two y,a" (1982-84) "ay at CERN, Gm,va, wat inv,lved in th,inve"igatiom 'f nutka, p,op"ti" 'f mon than 100 ,hott lived ;'ot'p"/;',m",, ming "Ilin,a, fa;t

bMm W", 'pm"","py, at th, ISOLDE fitdlity. P",mtly, h, i, pu,,"ing hi, int"," in high-""Iuti,n 'p""""py 'f

wnthaniM' and a"inid". D,Ahmd i, th, P",idmtofth, Iadian S,d,ty 'f Atomi,andM,Ie",Ia, Ph]'i".

a,"niM'.

D, A. Vmug'palanioind Sp""""py Div;'i,n, BARC in 1970 aJi" p-aduati,nfr,m K"alaUniv"'ity. H,did h;,Ph.DinPh]'i"fr'm th, Univ",ity ,fMumbai in i982. H,h", ",",k,d '"vi'iting"imti" at th, ISOLDEfit'ilityat CERN,GmtVa,in 1985 and Uta,a "Ilab"ato' in th,Ji"t tim, ,n lin, m,a;unmmtof iwtop',hiji andhyp"Jin,',,"'tun of ,hott livedgoldi,otop"ming&wnan" I,ni,a",n Sp""o",pi, t"hniqu,. H, aloow"k,d", vi,i"ng"imt;'t at th, Imtitu" 'fPhY'i", Univmity of Mainz, G,=any, in 1989 - i990. Hi, Ji,1d 'f 'p"iali"ti,n ;, HighR"oluti,n Atomit Sp""""py. P",mtly h, ;, involvedin th, 'p""""py 'f IanthaniM'and

H, h", m,n than50publi,ati,"" m,"1yinin"ma",nal iouma/i.

BARC, in i990 aJi" completion ,fpo"p-aduation in

Univmity, Kolhapnt. Hi, Ji,1dof ""anh i, HighR"oluti,n Studi" 'f Sp""a of Lanthanid"and A"inid,,: Hi, ",w,h atti"', have b,mpubliohd in national and iot"national "nfinn", and iouma/i.

D, A. &manuiam b", b,m a;",ia"d with th, T"mbay Plutonium Plant ,in" i" in"p"on. Ini910, h, h", 'p"ialiud in th, np"'",ing offa;t na"" ft,/i at CEA, Ftan". A, H,ad PDD, h,

i, "'po",ibl, fit' plutonium p"""ing and P""" "n"01 analyti,al 'p"ati,", at th, T"mbay

Plant and ft' "fting up th, lab""to') 'Y"'m, in th, new p"""ing p"i"" lik, KARP, FUS, ,ft.H;, R&-D int""" intiuM PUREX and THOREX p"'", Jro,wpmmt, automa"on in Pu aad

m U p,odu" p"""ing, pattitioning and moOt') 'f min" a"iniM' and impmant fi"i,n p,odu",uad" P&T p"p-am.

. It .

I 62 I--

ELECTRON BEAM WELDING OFCOPPER TO A151-30455

B.K. ShahAtomic Fuels Division

T.K.Saha and A.K,RayLaser and Plasma Technology Division

and

K. Bhanumurthy and G. B.KaleMaterials Science Division

Bhabha Atomic Research Centre

A bslracl

Copper, when welded to Siainiess Sleel, causes hot cracking in Ihe heal affecled zone (HAZ),

The amount of copper Ihal mells and mixes with the SS in the weld pool does nol cause much

problem. However the Copper enriched HAZ on the SS side can reach a temperalure 01 which

Copper melt.s and penelrotes the grain boundaries of SS. This phenomenon may resull in grain

boundaries weakening and may cause cracking. Electron Beam (E8) Welding which is havingextremely low HAZ because afits very low heat input, can be well suitedfar IhejUsion welding

of Copper to SS. EB welding of Copper to SS was carried out for Ihe fabrication of Rotating

Anode of X-ray generator to be used in Linear Acceleralor at Cenler for Advance Technology,

Indore. A number of dummy pieces were welded inilially with different weld paramelers. Some

of the weldings thai were carried oul 01 lower weld speed showed micro-cracks. Metallography

of these specimens has traced grain boundary liquation of the Copper in SS. The authors willdi.Ku." the weld procedu'Z, the mechanical and metallographic evaluations of the welds and

some of the techniques adapled to achieve defect free EB welding of the above dissimilarmaterial

Introduction

EB WELDING 15 THE BEST

choice foe welding of di"imilatmaterials because of i" low heat

inpUt, high power densiry and preciselycontrolled beam. Moreover, EBW can

provide purest welding environment sincerhewelding is normally carried out in vacuum,

Copper ro 55 weld joint has significant rolesto play in the fields of heat t,"nsfer, power

generation and transmi"ion, cryogenics,

electrical and electronics. Rotating anode

(Fig. I), which consistS of tWo copper to 55

join" is a component of X-ray generation

equipment, being used in Linear Accelerator,

that has been developed in Center for

Advance Technology, During EB welding

trial of rhe above component, problems like

heavy spurrering, bending of rhe beam and

micro-cracks were noriced. 5purrering and

bending problem was eliminated by proper

focusing and by off-setting of rhe electron

beam, Most probable cause of the micro-

I 63 I--

cracks seems to be rhe grain boundary

liquarion of HAZ of stainless steel by liquid

copper as suggested by Savage'. Several EB

welded rest specimens were prepared at

various powers and speeds to invc>tigate

actual reasons of cracking and ro find out the

solurion of the prohlem.

Fig. I Schemati, oj "tating anode

Fig. Ib WelMdmtatingan"k

Experimental Set Up

All the weldings have been carried our by

using an EB welding machine, developed

indigenously in BARC, that is working since

last 18 yem.

Specificatiom of the machine: Specificatioo>

of the EB welder is as follow"

Capacity:

Acce/erating vo/tag"E/cctron Gun vacuum:

Chamber vacuum:

Chamber size:

6kW

150 kV

5x1O" mbar

5x10'mb"

1500 x 1000x

1000 mm'

20 --2000 mmSpad.X-Ytab/e:

Speed.rotary tab/"

per min.

0.5 -- 20 rpm

Movements of X-Y table and rotary

manipulator are programmable. Focusedbeam diammr is about O.5mm at modem"

power and about 2mm at maximum poweL

Mounting of the te;t spedmen : Rotating anode

was mounted on the rotary table of the work

chamber at an angle of 45 degree for the first

weld and then horiwntally for the second. The

tc>t specimens, that arc essenrially 3mm thick

plates, were mounted on specially d",igned

holding fixmees. CoPP" end-taps have been

provided at starting and finishing ends of the test

specimens. One millimeter thick tantalum

backing plate was used for the test coupons to

avoid excessive pencrtation. Tantalum has been

chosen because of irs good behavior as backing

plate' attributed to its high melting point, good

thermal conductiviry and non-contaminating

nature.

J 64 I--

Beam current

Table I: lnirial weld paramerers for rotating anode

Job speed

15mA

25mA

15 cnilmin.

90 en1Jmin.

Table n: Weld parameters for test coupons

Weld Parameters

BeWii¥

Cuc<ent(mA)

16 ..

2420

281418

The weld renmarion requirement for the

Rotating anode w", 3 mm. The followingweldparameters were selected to provide 3mm

penetration on copper at lowand high powers.

Table III: Tensile test result

Paramaers jOr T", Coupons: Table 11 recorded

the various weld parameters with which the

weldings of the teSt specimens were carried out.

Speed

(emlmin.).

30

100

100

120

20

100

The above test coupons were prepared fo,

Tensile teSt, Micro hardness analysis,

Micrography including SEM and for Electron

probe micro analysis (EPMA). Pre-heat p",ses at

low cuc<ent were carried out before all the

welding. PoSt-weld cosmetic passes were

provided in a few =es where sputtering or

undereut had taken place. Vacuum in electron

gun and inside the work chamber was 5xlO .,

mbar and 5x 10" mbar respectively during the

welding operation.

Results

Tensik test : From the resulrs of the tensile teSt,

given in Table-Ill, it is observed that the welds,

that were carried out at higher speeds (sample

no: 2,3 and 4) have shown higher Yield Strength.

Sample no. 3, which - welded with off-setring

the beam by less than O.5mm on copper side, has

shown loweSt UTS. In =e of sample no. 6, the

electron beam was aligned at exactly on the joint.

I 65 I--

F:iilure 0.2% YS

location (MPa)

weld fail 98

weld fail 104.60

weld fail 88

weld fail 124.90

PIM(SS) 78.90

fail

The weld pool in this case had diverted towards

55 side and rhe specimen did not have full

penetration hence its tensile strength was nortested.

Micro-hardness analysis: The micw hardness

analysis were carried our for sample no. 2, 3 and5. Two lines were selected on each welded

section, near the top bead and near the weldtoot. VPN. values were recorded at an interval of

O.lmm along this line ftom the center, until the

readings stabilized. Fifteen to tWenty readings

were taken for each side of the welds among

which the maximum and the minimum values

are recorded in Table-IV. It could be observed

fwm the table, there is no significant change in

hardness value> on 55 side. However on Cu side,

variation in sample number 3, and 5 is

significant.Whereas sample number 2, that has

been welded at higher speed did not suffer much

change in hardness.

Table II!,Temile test result

Table IV, Vickers p)Tamid test

Max. Val~e I Min.

load, 100gms. 20x

J 66 /--

Microsrructural Investigation ofthe Weld

The typical optical microgcaphs fa< the

welded specimens 3. 4 and 5 are shown

in Fig.2, 3 and 4 respectively. The optical

micrograph corresponding ro Fig. 2 shows the

presence of micro cmks originating at the Cu

HAZ and propagating into the weld pool.

There are no such kind of cracks or

micropores visible in sample no 4(Fig.3). This

interface is rather sharp and devoid of any

microcracks. However for the specimen 5. the

micrograph indieated mierocracks. A typieal

scanning elecrron micrograph for rhe

specimen 5 is shown Fig. 4. This microgriph

dearly indicated the narrow HAZ. typical of

EB welded specimens. In addition. the

micrograph also indicates microcracks

originating at HAZand propagating into the

Stainless Steel. The migration of the liquid

copper into these cracks could also be noriced.

Fig.2 Mi""",k;dM~p,Jin w,Id(oampk,w. 3.low'ff"').

I 67 /--

Fig. 3 Mi",-"rnctu" in;p"imm no. 4 (wdkda< IOOcm/min)

J 68 I--

Electron probe micro anao/sis: Both point

counting and intensiry pmfiles fot the

Fe(K-alpha), Ct(K-alpha), Ni(K-alpha) and

Cu(K-alpha), eleme"" moss the interface

have been established by EPMA. The electmn

gun of EPMA was operated 15 keY and astabilized beam current of 20nA. ZAF

software' has been used to convert the

intensity to atomic concentrarlons. A rypical

elemental distriburion cortesponding to

the specimen no. 2 is shown in Fig. 5.

.."",,-

Fig. 5 EPMA pmfiks ft. 'pcdmm "". 2

A nearly homogenous distribution of Fe, Cr,

Ni, and Cu could be seen fmm rhis pmfiles.

However the behavior of Cu-Ni binary is

quite complimentary to Fe-Cr system'. Point

coUnt analysis corresponding to rhree regions

marked (I), (2) and (3) in Fig. have been

corrected by ZAF pmcedure and these results

are listed in Table V. The weld pool

essentially consists of Cu (90 to 92

at.'Yo).There is also some dissolution of Fe

(6.5 at 'Yo)and very small quantiry OfCr. andNi. It can be seen fmm this table rhar rhe

composition ofCu and Ni goes down and the

same of the Fe and Cr goes up ar point(l) and

(3) as compared to corresponding

composition at point(2).

Discussion

Dming the welding operation, it was

observed that if the beam is aligned exactly on

the joint, a negligible amount of Cu melts

whereas mmt of the melting takes place on 55

side. From the beam pmfile, it seems the

beam might have changed its path towards

stainless steel. These phenomena may be

amibuted to the following reason" (a):Largedifference of thermal conductivities between

Cu and 55. (b):Deveiopment of magnetism in

non magnetic steel due to phase change.i.e

ferrite formation during the melting ptocess.

(c):Pmducrion of electm motive force due to

dissimilar metal welding by EB.

However in rhis case the first teason is

predominant. To eliminate the pmblem, itwas decided to shift the EB towards the Cu

side of rhe joint. Two off-setring parameters,

a)0.2mm and b)0.5mm to Imm were (both at

higher speed) chmen. Tensile test result

shows rhar the welded specimen with 0.2mm

off-setring (specimen no. 3) possesed poor

yield strength(Y5) and ultimare tensile

strength(UT5). Whereas specimens that have

been welded by off-setting the beam more

rhan 0.5mm, possesed good Y5 and UT5.

Micro hardness test (Table-IV), also revealed

that there is a large variation in hardness value

on Cu side of the weld pool for specimen

no.3, whereas for the specimens, with more

beam off set, this variation is negligible. This

fact was confitmed by the micmstructural

investigation of specimen no. 3(Fig.2), which

shows presence of smaller microcracks.

Micmstructmal investigations confirmed

I 69 I--

ab,ence of micmcraoks in 'pecimem welded

at higher weld 'peed, (JOOcm/min. or more).

Wher"", during the low 'peed weldinp,

micmcraoks appeared at HAZ and pmpagared

thmugh "ainles, "eel parent metal (Fig. 4).

Thi, fact h", been confirmed by temile te"reml" and micm hardne" examinatiom. Thi,

result could be attributed to the fact that at

highet 'peed theee may be very limited time

fot diffusion and ,egregation of ,olute

element duting the cooling cycle.

Conclusion

Autogenom wund welding ofCu to AlSI 304

SS i, fe",ible by EBW ptoW', Fabrication of

a number of rotating anode, have been catried

out with 120kV and 26mA focmed beam.

The lineat 'peed of the job w" ,elected at

100cm/min. The electrou beam w", aligned

at a di,tance of Imm fmm the joint on Cu

,ide. Low power pre-heat p"" w"' pmvided

fot every job. Pre"ure tW " well "' He-leak

detectioo te" ware catried our on all the job,

and integriry of weld join" were found to be

mi,factory.

Acknowledgement

Authors are thankful to Dr.N.Venkatramani,

Head, L"et & Pla,ma Technology Divi,ion

fot hi, con,,"nt encouragement for thi, work.

Authors are grateful to Dt.S.Banerjee,

Aswciate Ditector, Metallurgy Gtoup,

BARC, for hi, mpport.

References

I. Savage W.F, Nipple, and Fetal E,

Intergrannular atrack of "eel by molten

copper, Welding Journal, Vo1.57.1.

2. TK.Saha, A.R.Bi,w", and AK.Ray

:Effect of Backing Plate Material on SS

304EB Welding, paper pre,ented in

International conference on Vacuum

,cience and technology and SRS Vacuum

'y"em, January 30- Feb2, 1995, Centre

For Advance Technology, Indore, India.

3. Thakur AV, Kumar S.C, Raju P.T, Ray

AK, Sinha AK, Varghe,e P.M, Vijayan T

and Ro"gi V.K, Report on Partial

vacuum E.B.Welding Machine for

welding preci,e compone@.

4. R.W.Cahm, P.H","n, E.J.Kumar,

Editor, Material Science and Technology,a comrehemive treatment, Volume:2B.

5. P.B.Ma"abki, Editor, Binary alloy ph"e

diagram, 2nd edition, American Sociery

For Metal" Metal'park, Ohio, 1990.

I 70 I--

About the authors.

Mr TK Saha joined BARC in 1980. He graduated from the Institution of Engineers

(India) in mechanical engineering. Pmently he is working in Laser and Plasma

Technology Division and is engaged in electron beam welding activities. He is

responsible fOr development of welding procedure fOr some important components such as

canned motor, centrifUge, coronet, rotary anode, Ni-electrode, reflector and shut-of plate

fOr KAMINI He has 12 publications to his credit.

Dr A.K Ray graduated from lIT, Karaghpur, and obtained his MSc. Tech and Ph.D.

from lIT, Powai. He joined the 11. Batch of BARC Training SchooL Since then he is

engaged in the development of electron beam melting, welding and evaporation

equipment. He has about 25 publications to his credit.

Mr B.K Shah graduated from R.I T, jamshedpur, in metallurgy. He did M Tech. from

liT, Bombay, in Corrosion Science 6- Engineering. He is having work experience in

fabrication of nuclear JUeI and reactor components, metallurgical evaluation and failure

analysis, metallurgical characterization by NDT and corrosion study fOr alloys. He has

about 90 technical papers published in v.,ious proceedings and journa&.

Dr K Bhanumurthy did his Ph.D. in metallurgyand is having 20 years of experiencein the field of

diffusionand applicationofEPMA. He has workedin GermanyonHumboldt FoundationFellowship.

Dr G.B. Kale did his B.£., MSc. Tech. and Ph.D. in metallurgy. He joined the 15" Batch

of BARC Training School. He has 28 years of experience in the field of diffUsion and

application of EPMA. He has worked as a visiting scientist in Gertnany under Inda-FRG

bilateral programme.

. . .

I 71 I---

PHOSPHORUS DETERMINATION BYDERIVATIVE NEUTRON ACTIVATION

ANAL YSIS

Y. M. Scindia, A. G. C. Nair, A. V. R. Reddy and S. B. ManoharRadiochemistry Division

Bhabha Atomic Research Centre

Introduction

PHOSPHORUS IS AN IMPORTANT

element in biological, physiological andenvironmental sciences. It is one of the

few elements, which is not amenable for direct

Neutwn Activation Analysis (NAA). This

problem is circumvented using Derivative

Neutron Activation Analysis (DNAA) methnd

(Ehmann 1987). Phosphorus is stoichio-

meterically complexed with a surrogate element

having superim nucleat properties, which can be

easily assayed by NAA. The pwcedute involves

selectively complexing phosphmm with

vanadium and molybdenum in acidic medium as

molybdovanadophosphmic acid (MVPA) and

extracting the complex into methyl isobudy

ketone (MIBK). The organic phase was amlyzed

by UV-Visible spectwscopy and NAA. Studies

were carried out on the complexation and

extraction behavior of the MVPA complex in

order to carry out DNAA. This method is tested

to estimate phosphorm in Certified Reference

Materials and water samples

Experimental

All the reagents used were of AR grade. A stock

solution of phosphorus was prepared from

potassium dihyhwgen phosphate (KH2PO4)

and horn this a standard containing 0.025

mg/ml of phosphorus was prepared by dilution.

Vanadium carriers of O.OIM and molybdenum

carrier of O.IM were prepared fwm ammonium

metavanadate and ammonium molybdate 4-

hydrate respectively. Methyl Isobutyl Ketone

(MIBK) used for preconcentration of the

complex was of BDH make. All the standard

water samples were prepared using de-ionized

wateL The concentration of phosphorus ranged

fwm 0.02 to 20 ~glg. Two Certified Reference

Materials (CRMs), namely, A-13 (freezed

animal blood), V-I0 (hay sample) obtained from

IAEA were dissolved in 3 ml of conc. HNO3

and 0.5 ml of cone. HCIO,. These were made

up to 25 ml in O.IM. HNO3. Sample solutions

were rtansferred by weight basis.

Results and Discussion

In order to determine the stoichiomerry of the

MVPA complex, two sets of experiments were

carried out. In the first ser of experiments,

vanadiom concentration was kept constant (250

~g), with molybdenum in excess (2500 ~g) and

the concenrtation of phosphorus was vatied. The

emacted MVPA complex was analyzed using

UV-Visible spectrophotommL Fig. 1 shows the

variation of optical density as a function of

phosphorus concenrtation from which vanadiom

to phosphorus miD was found to be 2:1. In the

second set of experiment vanadium and

phosphorus concentrations were kept constant inthe ratio of 2:1 and the concentration of

molybdenum was vatied.

I 72 I--

v ~ 250 >'9Me> =c 20 ""9

1 2

0 50 100 150 200 250

Amount of P ("9)

300 350 400

Fig. 1. Va,iati", aJabomban" wtth ph"p!"m, wn"nt"ti,n

-.----2.5

V ~.250 "9P ~ 75 "9

Fig. 2. Vatiati,n aJab"tba"" with nwlybdenum w",entcatiM'

I 73 I--

Fig. 2 shows the vaeiation of optical density as

function of molybdenum concentmion. The

mole ratio between phosphmm, vamdium, and

molybdenum was found to he 12,10 undet theseconditions.

Neutron activated samples WeCt assayed using

high-tewlution gamma ray specttometet. The

gamma ray spectcum of the n,"tmn actinted

MVPA complex is shown in Fig. 3. It can be

seen fmm the gamma ray spectcum that the

chatactetistic gamma tays of silicon and

100

80

U)C:::J 60a

U

>ill~=~.~

40

20

00 500 1000 1500 2000 2500

CHANNEL NUMBER

3500

getmanium that ate also known to fotm

hetempoly acids with molybdenum and that aCt

ptesent in the matrix, do not intetfete in thc

analysis. The execaneous gamma ray peaks ace

due to 101Mo_lOlTc (191 keY, 307 keV) and

that of 38Cl (1642 keV)) ptesent as imputitics in

polypmpylene cube. The method was tested fot

lineat analytical tesponse by using standaed

addition method ovet a phosphocus

concentmion range of 0.02-0.20 ~g/g.

l!~~~:>

~

>ill

~0'>~

>ill

~~.,-<0

,,'-"2'

3000

Fig. 3 Gamma-my spmmm a/th, "cut"" nctiwld MVPA wmph

I 74 I--

Table 1 , Rewlr of >tandard water mnple;

FrK4. Plw'pi",w ,"""ntmti,," " 52V"""ty

In Fig. 4 "y ",;vity w", plotted a a; func,;on of

phospho,"s concenttation. The ,.elarionship

hetwccn "y ,criviry and phospho,"; content was

foond to be linear, with a conehrioncoefficient(;) of 0.998. Table I shows the r"ults

of phosphorus concentration in standard wat"

;amples analyzed. Upto 25-ml of water could be

pteconcenttated effectively ",ing 5 ml of MlBK.

The mea;mcd pho;phoru; content in the CRMs,

namely A-13 (animal hlood) and V-IO (H,y

sample) are given in Tahle 2. The mOt quoted is

the standard deviation (lIT) from ttiplicore

mea;memc<m. The percent rel,tive srondard

deviation (md) obtained by this method is 3-7

% ,nd the percenuge deviation from the

repotted "Iue is of the order of 4-8 %. Tbe

main mots are associated with the counting

I 75 I--

statistics. The absolute limit of deteCtion [LODJ

under Out experimental conditions of 15 min

irradiation,S min cooling and a neutron flux was

of rhe order 10 12 n cm-2 s -1 was calculared

using rhe Cmrie's formula (Cmrie, 19G8)J

Table 2, Results of the analysis of pbosphorusin the two IAEA Cerrified Reference Materials

(CRM)

LOD . 2.71 + 3.29 ~Cb IL" where Cb is rhe

hackground counts and L, is rhe live time. LOD

was found to be 0.07 ng in an interference free

a>odition. These values are mperior to those

teporred by Allen ",d Hahn, and Ehmann

(1987). Allen and Hahn used (he

tungstophosphoric acid complex. In this complex

tungsten is the surrogare element and rhe

aCtivated product 'v W was used to arrivc at the

phosphorus concentration. They have reporred a

detecrion limit of 4 ng and I ng respectively.These values ate much lower rhan rhe mcrhod

using rhe fast neutron reaction 3 I P(n,«)'"Al and

the limit quoted for ion selective electrode (4

Jig) and spectrophotomctry (10 Jig) Jig). OUt

value compares better with rhe reporred dara.

Conclusion

A preconcentrarion chemical procedure

accompanied by derivative neutron activation

was developed and used to estimate phosphorus.

The chmcreristi" of (he complex a<e evaluated

in rerms of rhe stoichiomerry and thc

discrepancy with the reporred literatute observedis atrributed ro different acid concentra<ion

conditions. The method can be applied over a

wide concentration range in varying matrices.

Using rhis rechnique rhe absolute limir of

detection achicved is 0.07ng. The entire

experiment including the counting of thc

samples can be completed within 3 hours. The

merhod is promising especially for water and

biological samples.

Acknowledgement

The authors a<e thankful (0 Mr R.N. Acharya for

his constructive suggestions during the progressof this work.

References

1. Currie LA Limirs for Qualirative Derection

and quantitative Derermination, Anal.Chern. (l9G8) 40: 586.

2. Ehmann WD, Young RC, Koppcnaa!OW,Jones WC, and Prasad MN. Derivarive

techniques in Acrivation Analysis,' J.Radioanal.Nucl. Chern (1987) 112: 71-87.

the Best pap":J'resented in the lit' NJ

'eldat'4't!gaonduring Dlrember 26-29, 1.

I 76 I--

Abautthe autha" ....

M, Yognh M Sdndia obtained hu M.S" in Chtmimy from Mumbai Univmity in 1998. He

joined BARC iu January 1999 0; a Juni" R"w,h Fellow und" the Mumbai Uuivmity-DAE

ftllowthip ;cheme and u pmently "",king in Rndi"hemntry Divnian. H;, meaI'Chfie"" are T"t«Ekment; Det=inatian in Envi'Onmental and BiologicalMatTice>..ing Activation Tethniqun.

D, A. G. C. Nai, joined BARC aft" go-nduatianfrom K"alo Univmity in 1969 and obtained hi,

Ph.D. from Mumbai Univmity in 1989. Hit main am" afintmtt.,e ,ndiochemicalttudm of

flliian and nen"an activatian analyt;,. During the cou"e of thm ,codi",. """al ,ndi"hemical

"pamrian p,aceduet, fi" flliian p'Odum like Mo, Xe, In. Pd, etc. wm developed. Anath" fieldwh", he hm ketn intmst i; k, "anda,dized nm"an activatian analy,i, and ,ndima",

appli,atiam. Pmently he ;, engagedin P,ampt Gamma Ray Activation Analy,n te,hnique. He hm

been an !AEA expm to the Ghana Atomi< Eneegy Cammi"ian. Ghana He hm ma'f than 70

publicatiom in int,,"atianal jaurnali and tympo,ia.

D, A. VR. Reddy abtained hi; MS,. in Chemi"ry in 1974 from S,i Venkate,wam Uni""ity,

Timpati, Andhm Peadnh. He joined Radiochem;,try Div;,ian, BARC, th'Ough the BARC TiainingSchool in 1977 and;, at pment Head. Nu&., Chemi,try Section. Hi, am" af m"I'Ch aCt nuck.,

ji;,ion. nud", ,eactiam, nude., 'pect",copy. heavy element ,hemi,try. activatian analy;;,.

nondmm"ive a;;ay method, and p"pmatian of'pecial ,ndi""i" tmgm. He hm m"e than 100

publi,atiam to hi, mdit. D, Reddy hm co-auth",d th"e book, and hm edited fi" oolumn. Since

1996. he hm been a memb" af lUPAO Camm,,"ian an "Radi"hem;,try and Nuck.,

Techniqun': He "",ked during t992-93 in the Inttitut Fu" Ketnchemie, Univmity af Mainz. G=any, on the

,hetnittry of "ama"inide element;. Du,ing 1999-2000, m a technical offi'" in International Atomi, Eneegy Agency,

Vimna, he w"k,d on Radi"h,mi"ry and Nud,., Analytical technique;,

D, S.B. Manoh., abtained hn Mmt'" degete in Chemutry fram the Univmity of Poona in 1965.

He Joined Radi"hemi,try Divuion. BARC th'Ough the BARC Tiaining School and ;, at pment

Ifead. Radio,hemi"ry Divi,ion. Ifi, mea, af ""m,h me nudea, fi"ian, nudem "action, nudm

'pm,",copy, mdi"/,,mi,.1 "pamtion" nmt"n aaicatian analy,i" nudem p"bn, ,ndi"aivity in the

envi'Onment and "'"lopment af nan-"'ttmcti" tWOy (NDA) technique;. He hm publithtd 70

"ientife papm in i""national journali and ma" than 100 in rympotia. He hm autho"d a book

"Exp"immt; in Radi"hemutry" and hm edited the Symp"ium p"",ding; NUCAR 95 and NUCAR 99. D,. Manah.,

we;; in"l"d in an IAF.A intmampmi"n n"ma"ment; ofmdionudidn in go-a;; ;ampln colle,ted afiet Chernobyl accident.

In thi, "nnmian he ."ended the IAEA comultant; metting at Cnddeach, F,ance du,ing 15-17 July, 1987 and hm

con"ibuted w p"p.,atian of technical "pon 295 titled "Mcmu"ment af ,ndwnuclide, in food and envi"nment'; lAEA

(t989). D, Manah.,;, Ph.D. guUkfa' Mumbai Univmityandfiveafh;, tt;u/ent$ have beenawo,"'d Ph.D. degete in the

""tfau, yMn. He it a memb~of many "ientific msodatia", and Pmi"'nt (ekct) of Indian Anadatian afNuckae eI"",;",

and Allied Scienti", (IANCAS).

. . -0-. .

I 77 I--

DETERMINATION OF H2CONTENT INZIRCALOY USING HOT VACUUM

EXTRACTION -QUADRUPOLE MASS

SPECTROMETRY (HVE-QMS)

V.S. Sayl, Rajendra Prasad. K.L. Ramakumar, C.S. Vadav, P.S. Shankaran,G.C. Chhapru, V. Venugopal, S.K. Aggarwal, H.C. Jain and D.D. Sood

FuelChemistryDivisionBhabhaAtomicResearchCentre

Introduction

HYDROGEN HAS VERY LOW

,olubiliry « 1 ppmw at room

remperature) in zircaloy which i,

widely used in nuclear technology.

Comequently, the presence of hydrogen

exceeding a certain 'pecificarion limir in zircaloy

components in rhermal reaeron evenrually leads

ro the formarion of zirconium hydride ultimately

remlring in hydrogen emhrittlement [1.2J.

Dererminarion of hydrogen/deuterium content

in zircaloy coolant channel, of pressurised heavywarer reacron (PHWRs) ha,. therefore. been

identified a' one of rhe crucial pOH irradiation

examinarion ta,ks for evaluating the integrity ofthe coolant channels for sustained, trouhle-free

use [3].

This papet gives rhe details of a hot vacuum

extraction technique coupled to an on-line

quadrupole mass spectromerer for the

determination of hydrogen in zircaloy ,amples.

Experimental

A high vacuum 'YHem ha, been fabricated for

hydrogen extraction and determination. In a

rypical analysis, the sample weighing abour 20

mg is raken in rhe quartz reaction rube. The

entire system is evacuared to a vacuum betrcr

than 10' mbar. The sample in the quam tube i,

heated by a resistance furnace. Degassing of the

sample is catried our at 450°C for t5 min. The

valve at the outlet end of the quam tube is closed

and the temperature is ,lowly raised at lOo/min

to a tempemute of 1O50°C and maintained for

15 min. The valve is then opened and the

evolved gase' are extraered out of rhe quartz tube

by an ejector pump for 15 min and allowed to

expand to a known volume. Pressure in the

system is measured by a Mcleod gauge. The

evolved gas composition is determined by

feeding the gases to the on-line quadrnpolc mass

spectrometer (DATAQUAD Model DXM from

Mis Anglo Scientific. UK) through a mietoleakvalve.

Prior to rhe aerual sample analysis. the expansion

volume was calibrated by analysing titanium Heel

LECO analy,ed standard with known hydrogen

concentration (28.II5.1 ppmw)

Results and Discussion

A typical mas, spectrum of rhe evolved gasesindicated the ptesence, in adelition to hydrogenion peaks (mlz. 1,2,3, and 4), of moisture

J 78 /--

Sample-weight(g)

Table 1 , Concentrarion of hydrogen in zircaIoy sample. determined by HVE-QMS

0.10$3$0.12961O.lInO0.124660.126250.135710.047750.129$6

mh) = 18), CO+N, (mh = 28), 0, (mh = 32)and CO, (mh = 44).

Pcioc ro each sample analysis, a blank spectrum

was cecorded foe all the masses of interest. The

signal intensirics at difbenr mh values were

coHecred foe the coHesponding blank

contcibution. The total intensity of hydrogen

(I(Hydwgen» is given by ![H]/2+I[H,I. If

deutecium is also pcesent, the intensities at mh =

3 O[HD]) and 4(1[0,]) are also added. Relarive

intensity of hydrogen ro the roral intensity

(I(Hydrogen)+I(H,O)+I)CO)+I(O,}+I(CO,»

was used to obtain the pania! pressure due ro

hydwgen isoropes as a fcaction of total pcessme

of the evolved gases. Table I gives the hydrogen

content in a zircaloy sample in replicate analyses

employing HVE-QMS. The same sample has

been analysed by employing inen gas fusion

(IGF) method using a commeccial hydrogen

detecminator, the cesults of which are also given

in the same Table. It is clearly seen thar the

agreement betWeen the results is good.

Conclusions

Coifc.

OfH,(ppmw)~10.6w:Jill12.0w:JM10.4£0.6

It is possible ro get isoropic information and also

the composition of evolved gas" using HVE-

QMS technique. The information on hydrogen

and deuterimn contents in zircaloy wOuld help in

the evaluation of its "health" particularly with

respect to hydrogen embrirtlement. ! ,f.'l

References

I. W.L Mudge Jr., in Zirconimn Alloys,

Ametican SocietyOf Metals, Ohio (1953) p146.

2. B. Watkins, A. Cowan, COW. Party andB.W. Pickles, in Application - Related

Phenomena in Zirconimn and its Alloys,ASTM Special Pub. 458, American Societyfor Testing and Materials, Philadelphia0968) p 141.

3. G.J. Field, J.T. Dunn and B.A.Cheadle,

Canadian Metallmgical Quarterly, 24(1985) 181 and other pape"

I 79 I-------

About th, autho"..

D, y,lku, S"ha Sayi joined BARC in

1978 aft" obtaining MS" (Phy;ical

Ch,mutryin 1972) and Ph.D. (1977)

from S,i Vmka"twa,a Uniomity. H,

i; mainlv.involo<d in ,h,mical qualityhm a"o ,a"ied out"m,

ma",ia".

D,KL.includefi' tm"pm"dum.

M, Cs. Yadoo obtained hu MSc.

nudwfU&

Ba"hH, u a

Mumbai Univmity. Hi, mam amaof im",;t u thmnodynamic; ofnudM> mamia". H, hat mac, than

180 publication; in mputed int"nationaljouma".

D, Sumh Kuma, Aggacwal. bom in1953, i, ""'mtly Head, Mm,Spmtmm,try S,mion of th, FudCh,mi,try Divi,ion, BARC H,m"io<d hu B.Sc. (Ham.) from GumNanak Dcu Univmity, Am,iua" in

1972 with two Gold M,do". H, joined th, lC" Batehof BARC Tmining School in 1972 and m"ived th,Homi Bhabha Awad. H, did hi, Ph.D. from BombayUnivmity in 1980. H, wocked at th, Univmity of

Antw"p, &Igium, on SOU"' Mm; Spmftom"ry(SSMS) fi' 6 month; 1982-83. H, had hi,Po;t-doaoml ftaining in GC-MS fi' "a",I,mm" dete,mination m ,ampl" at th,Univmity Vittinia H,alth Cmtm, USA.H, i; a of 300 ;ti,ntific publitatiom whichindud, 100 attid" publuh,d in mputed jou,"at. D,

,fed in "",al in"mational and

and in diffmnt in","ationalap"immu on TlMS and alpha

;pmtmm'tryoJPuandU H,i,a;pmiali;tinth'fi,ldof atomic mmt tp,amm,try and alpha ;pmtmm"ry andu im,m"d in oa,iom atomic mill, 'pmtmm,"ittmhniqu". Hu vth" amm of intm;t indud<dmftvth,mi;try and "Ivmt aftaaion. H, t,,-odISMAS m a S""tary du,ing 1992-1997 and u

Vi,,-Pmident (HQ) of ISMAS. H,mpm"nuth, Ex<"'tiv, Commit", of In"mational Mm,

Sp""mm",i, Confmn". H, hm vui"d "o"al

munfti" in Am"ita, Eump' and Au;tmlia at an "pmta; wdl m fi' deli",ing Imum. H, i, on, ofth, dito"

book, and i, a mognu,d Ph.D. Guid, of th,Uniomity.

Dt.H,CJain wm fitmmly, H,nd, Fud Ch,mi;tryDioi,ion, BARC Hu 'pmialuatiom at, Mm'Sp,amm,try, Alpha Spmftomttry, Rndioanalytital andNudca, Ch,mi;try. H, hm mauthUttd mUtt than 300publicatiom.

D,.D.D.Sood i, pmmtly Dim"" Divi,ion of Phytimland Ch,mical Scim"" lAEA, Vimna. H, wm fitmmlyDi,m"" Rndioch,mittry & ho"p' Gmup, BARC H,ha, mnd, pionming mntribution, " th, th,mi"") ofplutonium and vthm aainid" D,.Sood u th, authoc offlu, book, on Nudm and Radioch,mi,try.

. 0 .

I 80 /--

UPTAKE OF METAL IONS BYEXTRACTION CHROMATOGRAPHY USINGDMDBTDMA AS THE STATIONARY PHASE

S.Sriram, P.K.Mohapatra and V.K.ManchandaRadiochemistry Division

andLP.Badheka

Bio-organic Division

Bhabha Atomic Research Centre

Abstract

The aptake of U(VI), Pa(IV), Am(/II), Ea(IIl), Cs(l) ood Still) flOm nittic acid ;olation' by a no,,1 '"/taction

chcomatoglOphic ",in with dimethyldibatyltetlOd"yl-I,3-molonomide (DMDBTDMA) a; ",otionaty pha,,"

ha; been in",tigated The atda of aptake is Pa(IV»U(VI»>Am(III)-Ea(IIl»S.(II)-<:;s(/) Balch and

colamn "adie,; h~e been co..ied oal fat the wtPlion beha,io", of Nd (Am) !,am nit", acid wlotion The

aptake afNd (Am) in the ptmna afmaaa conanllOtion ofFe(IIl) ha" altO ban in""igoted

Introduction

Due to their chelating effect pemaalkyl

malonamide. like DMDBTDMA ace pwmi.ing

emamm, for a ho" of rei, terea and hexa"lent

actinide. from nireic acid medium [IJ and thu.

are u.eful for actinide partitioning fwm high

level wa;te, The main advantage; of thi. cia;. of

extractam; ace their innocuou. radiolytic and

chemical degcadarion pwdum and their ea;y

incinerability which make rhem pwmi.ing for

wa"e trearmem [2].

Extracrion chromatogcaphic "paration merhod.

combine the advamage. of both .olvem

extracrion and ion-exchange technique;

efficienrly [3]. The pce"m work deal. wirh

preparation, chacacreri;arion and we of novel

chwmatOgcaphic re.in material with

DMDBTDMA a; "atiomry pha" and

chwmo.orb -W a; the inert support.

Dimiburion behaviour of sevecal actinide. and

""ion produm wa; inve;tigated wing thi. re.in

material in batch a; well a. column .rudie., The

effect of macro concentrations of Fe(lII) on the

uptake of Am(lII) ha; aha been evaluated in

batch a; well a; column .rudie. in 4 M HNO,

medium. Column .rudie; al;o involve rhe

determination of bceakrhwugh capacity of Nd

(Am) under varying acidity condition;.

Experimental

The ligand DMDBTDMA wa; .ynrhe;ised inrhe laboratOryfollowinga reported method [4].

I 81 I--

The extraction chromatOgraphic resin w",

ptepated by equilibcating equal amount of (U

wt/wt) Chromosmb W obtained ftom John's

Manville and DMDBTDMA in acetone fm

about 24 hcs. Aftec blowing off the solvent by

passing N, gas the mate<ial was vaccum dtied co

constant weight. Radiomenic assay of "'Am,

""'"Eu, mCs and "~Sc was cmied out by

gamma counting in aNal (Tl) scintillation

detectm. >EV and "'Pu we<e estimated by alpha

scintillation counting employing tOluene based

emactive scintillatoL

The smption of the radionuclides from nitric

acid medium w"' measuced by contacting a

known amount of the tesin matecial (- 15-20mg) with a known volume of the desired acid

containing the radionacec in a theemoStated

worer bath for ! hOUL Dimiburion ratio (DM)

w", evaluated as the ratio of the activity pee gram

of the resin marerial to the acrivity per ml of the

aqueous phase. The columns wece peepaced by

packing about 500 mg of the resin matecial in a

glass column (4mm x IOmm). The flow rate wa>

adjusted co 4 to 6 drops per minute.

Results and Discussion

Fig.! shows the plot of DM with varying HNO,

concentration suggesting that the ocder of

extraction is Pu" > va," > Am" > Eu" > St" >

Cs'. Nitric acid uptake was found to be -6.0 ~

1.0% by the resin material in the range !-6M.

These observations are in confmmiry with the

solvent exnaction Studies ceponed earlier [5J.

Batch Studies for the sorption behaviour of

Am(IlI) at 4M HNO, under varying Nd loading

conditions (1.8-18.2 g/L) indicate decrease

in D,. co - 4.0 at 18.25 g/L ofNd (Table 1).

Fig. 1 Vadation olDM valu" with HNO, conan"ationjo' ,meal actinid" andpsion peaducls

J 82 I--

Table I, Am uptake from 4.0M HNO,

unde, varying Nd loading conditions

Table 2, Am uptake from 4.0M HNO,at mac,o concenttation of Fe(lII)

The p,esence of Fe(IlI) affects the ame,icium

ion ex"aceion significantly [6]. The effect of

m",o concentntion (0.5 -6 g/L) of Fe(IlI) on

Am(IlI) so'ption was investigated at 4.0M

HNO, (Table2). A significant demase in D,,"

was obsecved fwm ~48 (as pme "aw) to 1.85 in

p,esence of 6g/L of Fe(III). B,eakthwugh

capacity of the column mate,ial fm Am(IlI)

(using Img/mL Nd(lII) + "'Am tmcer) was

detctmined at various ni"ic acid concentrations

(I-6M HNO,) (Table 3). An inmasing trend in

breakthwugh capacity was found with acidity

upto 5M HNO,. ~ffect of macw amounts of

Fe(l1I) on the Nd(Am) loading was evaluated at

4M HNO, (Table 4). Column studies on the

effect of macwconcen"ation of Fe(IlI) on

Nd(Am) loading indicate decreasc in Am loadingsimilar to the batch studies. GmL of O.OIM

HNO, was sufficient to elute >95% of the

loaded Nd(Am).

Table 3, Variation ofb,eakth,ough capacity of

Nd(Am) at yatious niuic acid concenttations

Table 4, Effect of macm amounts ofFe(lII)

on Nd(Am) loading at 4M HNO,

1. c.Musikas; in the Pwceedings of the

Nuclear and Radiochemistry Symposium,

NUCAR-95,p.12.

2. Siddall T.H. III; J.lnmg and Nucl Chern.,

25,883 (1963).

3. T.Bmun and G.Ghmini (Eds) in

"Ex"action Chwmatogmphy", Vol. 2,

Elseyie" New Ymk (1975).

4. G.Thiollet and c.Musikas; Solv Ext and Ion

Exch., 7(5), 813 (1989).

5. G.R.Mahajan, D.R.Prabhu, V.K.Manchanda

and LP.Badheka; Waste Management (in

press).

6. c.Cuillerdier, c.Musikas and LNigond;

Sep. Sci. Tech., 28155 (1993).

About the autho",.

After obtaining hi; M.Sc. (Analytical Chemi,try) from Mumbai Univmity, Mr S. Sriram

joined Radiochemi,try Divi,ion, BARC in 1996mJunior Rmarch Fellow under the BARC

- Mumbai Univmity Collaboration Scheme fOr Ph.D (Chemistry). Hi; main area of

re,earch include, the ,cudie; on liquid - liquid extraction, extraction chromatography and

liquid membrane bmed "paratiom of actinides and ?,ion product, u,ing novel extractan".

Mr S. Sriram hm to hi, ctedit over 18 publicatiom in leading international jouma;, and

confiren",; 'ympo,ia.

Dr P. K Mohapatra joined the Radiochemi,try Divi,ion, BARC in 1987 after completing

hi, MSc. in Inorganic Chemi,trY from Utkal Univmity and graduatingfrom the 311' batch

of the BARC Training School. He wm awarded Ph.D. by Bombay Univmity in 1994.

Dr Mohapatra carried out Po,,-Doctoral research work at Univmity of Liege, Belgium,

under BOYSO1ST Fellow,hip, DST (1998 - 1999) and University of Mainz, Germany,

under Humboldt Fellowship (1999 - 2000) on MRI cont""t agen" and chemi,try of super

h'eavy elements, respectively. His research inte",fs include; the chemi,try of mactocyclic compounde and

separation "udies of actinides and ];"ion produ'" u,ing novel extractan". Dr. Mohapatra hm to hi; credit over

JOOpublicatiom in intemational jouma;, and confiren",.

Dr Ie K Manchanda joined the Radiochemi"ry Divi,ion, BARC in 1969 after graduating

from Delhi Univmity and from the 1L" batch of the BARC Training school. He WaJ

awarded Ph.D. by Bombay Univmity in 1975 and carried out Po,,-Doctral work at

UTEP, Texm, US.A. m Fulbright Scholar (1985-87). Hi; ",earch inte"," include

thermodynamics and kinetics of complexes of mactocyclic ligande with lanthanides and

actinides, physico-chemical "udies on actinide complexes, design and 'ynthesi, of novel

extractanfs jor actinides and chemical quality control of Pu baJedfUe;,. A recogni"d Guide in Chemi,try fOr

MSc. and Ph.D. by University of Mumbai, Dr. Manchanda currently heade the Actinide Chemi;try Section,

Radiochemistry Divi,ion. Dr. Manchanda hm over 200 publicatiom to hi; credit.

Dr LP.Badheka (Ph.D, chemi,try, Bombay Univmity, 1989) joined the Bio-organic

Divi,ion, BARC, in 1967. He carried out po" dactoral mearch at the Imtitute fOr

Pharmaceutical Biology at the Univmity of Munich (1994-95). Hi, current inte"," include

the 'ynth"" of organic ligande fOr actinide extraction.

. . .

I 84 I--

PREPARATION AND THERMAL STUDIESON

Pu(MoO 4)2AND Na2Pu (MoO 4)3

N.D.Dahale, Meera Keskar, K.D.Singh Mudher, R.Prasad and V.VenugopalFuel Chemistry Division

Bhabha Atomic Research Centre

Summary

THE SOLID STATE REACTIONS OF

Na MoO with Pu(MoO) were ca[[ied

ou: in different molar ;t~potcions at

various tempmtutes. Thermal Studies

of the oompounds have been Studied using

thermogravimetrir (TG) and differential thermal

analysis (DTA) teehniques. The produCtS formed

dUting the thermal decomposition of thc

reactantS were identified by X-ray diffraction

method. XRD data of Pu(MoO), and

Na'pu(MoO), were iudexed on o[[horhombic

and tetragonal system n,spectively. Ou heating

isothermally at 1200°C. Pu(MoO), gave PuG,

whereas Na'pu(MoO), formed a mixtUre of

PuG, and Na'puO, at 1400°c.

Introduction

Molybdenum is an important fission product

formed in large quantity in the nuclear reacrot.

Reaction of molybdeuum with other fission

productS ehanges the behaviour of the fuel.

Sodium metal is used as a ooolant in liquid metal

fast breeder teactotS (LMFBR). Uranium.

thorium and plutonium ate used as nuclear fuels.In accideutal oondition. sodium. actinides and

Mo may interaCt among themselves and form

different compounds. A sYStematic Study to

prepare and eharaCtetize some compounds iu

alkali mcral-acrinide-molybdcnum-oxygcn

syStem had been ca[[ied out by Diou [1,2].Tabuteau et.al had Studied alkali-metal-

plUtonium-molybdenum-oxygen quaternary

system by means of liquid-solid cquilibrium

diagrams and X-ray diffraction [3]. However.

thermal Studies on sodium plutonium

molybdates has not becn reportcd so fat. Earlier

we have reported X-ray diffraction aud thermalStudies on Tl-Th-Mo-O and Na-U-Mo-O

sYStems [4,SJ. In continuation of OUt earlier

work. the present work has been ca[[ied out to

stUdy the thermal behaviour of Pu(MoO.), and

Na'pu(MoO),.

Experimental

Pu(MoO), was prepated by heOting the mixtme

of PuG, and MoO, in U molat mio in

platinum boat in air, initially at SOO°C for 2hours and then further at 800°C for IS houtS.

Pu(MoO), and Na,MoO. were mixed in

different molar ratios and heated upto 600°C in

ait. TG and DTA patterns of the compounds

were recorded in platinum cups in Metrler

Thermoanalyzet at the me of 10°C/min in a

flowing stream of dty air. Preheated alumina was

J 851--

u,ed "' eefeeence macedal foe DTA

meameemem,. The peegee" of the ceaction and

pucity of the peeduct aftet each heating was

moniweed by taking X-tay diffeaction patteem

of the peeduct, on DIANO X-ray diffcactometer

u,ing CuKa cadiation (I- = 1.54178 A)

Results and Discussion

The XRD data of Pu(MoO), was indexed on

onhoehombic 'y"em with lanice paeameter> a= 9.42A. b = 10.05 A and c = 13.98 A and data

of Na,Pu(MoO), was indexed on «ttagonal'Y'tem with a = 5.18 A and c = 11.28 A.

TG and DTA curve' of Pu(MoO), i, shown in

Fig.1. TG curve ,howed no weighr 10" upee900'C, showing the rhermal "ability of thecompound. An endothermic DTA peak wasobserved at 950'C due ee the melting of the

compound. The end product foemedat 1200'Cw", confiemed"' roo, by weighr10" calcularionand by X-caydiffeactionmethod.

I 86 I----

Pu(MoO), and Na,MoO, mixed in eguimola<

pmponion and heated in ai, upro 600°C, leads

to the fo,mation of Na'pu(MoO), Fo,mation

of the compound can be desc,ibed by Eg. (1).

600°C

NaMoO(s)+Pu(MoO)(s)-Na:Pu(M~O),(s)" (1)

The,mogcam of Na'pu(MoO), is given in Fig.2.

TG cueve did not show any weight change upro 1000°c. The DTA cutve showed an

endothe,mic peak at 740°C due to the melting

of the compound. The X-cay difftaction panerns

of the compound befme and aftet melting we,e

identical, suggesting the congment melting of

the compound. Funhe, heating of

Na'pu(MoO), upro 1400°C led to the

fo,mation of mixture ofNaluO, and PuG,. The

decomposition of Na'pu(MoO), in ai, can be

shown by the following Eg. (2).

2 Na,Pu(MoO), (s) + 1/20, (g) -> Na,PuO, (s)

+PuO,(s)+6MoO,(g). ..(2)

The fo,mation of Na,PuO,(s) and PuO,(s) was

identified by weight loss calculation as well as

by X-cay diffcaction analysis.

The ,eaction ofPu(MoO), and Na,MoO, in 2:1mala< catio at 600°C did not fmm highe,molybdate. Howeve" the XRD panern ofpmduct was identified as mixtuce of

Na'pu(MoO), and Pu(MoO),

References

1. C. Dion and A. Noel, Bull, Soc. Chim.Fcance, (1983) 1-257.

2. C. Dion, Bull, Soc. Chilli. hance, (1981)371.

3. A. Tabuteau, M. Pages and W. F,eundlieh,Mat. Res. Bull.,7 (1972) 691.

4. N.D. Dabale, KL. Chawla and N.c.

Jayadevan, NUCAR - 95, Kalpakkam,Feb.21-24.

5. D. Dahale, Mem Keska" KD. Singh

M,\dhe" K.L. Chawla and V. Venugopal,ISAT - 98, Bangalme,Nov.24-25.

About theauthon ..

.

Aft" obtainingMSt. in Phy,italCbtmi"ryftom PoonaUnivmiry in 1979, M,. N.D.Dahaitjointd BARCin 1981.H;, maina"a of mtatth h", b"n p"Patationof n= tompounthby,.Iid,ta" "actiom and th", thatattnisationby X-rayand thttmal _both. Ht ;, aho involvedindevelopm,"tofX-rayJluamtente'ptttromttritmtthothofelemrntalanaIl'i,.Heh",pubI;,hed,""talpalm in international journa" and tymp.,ia.

Ajitt graduating in Pby<itt ftom Bombay Univmity in 1985, Mn. Mma K"kat joined Fuel

Chem;,try Div;,;.n in 1988. She obtained h" MSc. dW« in Pby<italChem;,try in january 2000.

H" field of intewt i, p"patation and thatatteri,.tion of attinide tompounth and eltmmtal analy,i,

by XRF

D, KD,Singh Mudh" joined BARC in 1971 aft" tompleting h" p.,t fl'nduation ftom 1fT Delhi in

Chem;,try and atqui,ing Ph.D. degr« ftom 1fT Mumbai. H;, main a"", of wea"h a" X-tay

diffiaclion, X-'ay fluowttnte and ThttmOthemitai in""ligatiom of actin""'. He h", pubI;,hed matt

than 100 papm in int,,""t;.na1 journ.. and tOn/",n",.

Aft" obtaining M.Sc. in Chem;,tryftom Allahabnd Univmiry (1966), M, Rajrndta P""nd joined 1ff

bat<hof BARC Ttaining School in 1967. H;,a"a ofinte"'t;, thttmodynamm ofn""'at mat"",h.

Dt. V. Vrnugopal ;, the Hend of Fuel Chem;,try Divition, BARC. He ;, ftom 14" batth of Ttaining

School He ;, a Ph.D. guide of Mumbai Univmity. Hi, main a"a of inte",t ;, thetmodynamia of

nutltat mate,ia"- He h", man than 180 publitatio", in "puttd intemationaljouma".

. . .

j 88 f--

A STUDY OF SOLID STATE REACTIONBETWEEN STRONTIUM CARBONATE AND

RUTHENIUM DIOXIDE

R. K.Mishra, J. G. Shah and R. G.YeotikarWaste Management Facilities, Tarapur

andS. R. Dharwadkar

Applied Chemistry Division

Bhabha Atomic Research Centre

Abstract

A solid state reaction between strontium carbonate and ruthenium oxide is studied employing

thermogravimetry, effluent gas analysis and XRD techniques. In addition to temperature, other

parameters such as ambient atmosphere and compaction of the reaction mixture influenced the

reaction rate. The rate of reaction was much higher in oxygen compared to that in argon. The

compaction of reaction mixture decreased the reaction rate.

Introduction

R:THENIUM (Ru) AND ALKALINE

earth elements such as strontium (Sr)

nd barium (Ba) are among the major

fission products [I]. During reprocessing of

spent fuel, these fission products fmm the majm

part of bigh level liquid radioactive waste

(HLW). These fission products are highly

radioactive and are immobilised in an inert

ma"ix. The steps commonly employed fm

management of HLW, are immobilisation of

HLW in the glass ma"ix, pouring in SS

canisters, their interim storage and ulrimate

disposal in underground repositories [2].

In general, two methods are employed fm

immobilisation of HLW in glass [3]. In the first,

the slurry containing glass fmming additives and

HL W are heared above the fusion temperature in

a fur~ace. The processes involved in the

vi"ificarion are evaporation. calcination and

fusion. The molten glass so formed. is then

poured into the SS canisters and "ansferred ro

the interim stmage. In the alternate procedure,

the waste is first calcined ro get the calcined

mass. The same and the preformed glass mixture

is heated above the fusion temperature and

poured into canisters. Some of the oxides such as

those of Ru, Te and Cs have appreciable

volariliry and therefore can vapmi,e from the

reaction mixture during vi"ification and can get

deposited on piping and other locations in rhe

plant.

The present study is aimed at "apping the

vapours of Ru from HLW during the stage of

calcination I vi"ification. It is observed thar, by

"apping the 'volarile Ru on alkaline earthcarbonate can convert Ru to alkaline earth

rurhenate, which is thermodynamically stable.

In order to understand the formarion of

rurhenare, efforts were made ro synthesize the

same. In this paper, we ptesent a case study of

I 89 I--

the solid state reaction between alkaline eanh

carbonate srCo, and the ruthenium dioxide forthe formation of SrRuO, and recommend theoptimum conditions under which suchcompounds can he preparedin pure form.

Experimental

All the chemicals used in this investigations were

of analytical grade putity. The alkaline eanh

carbo';;'tes and ruthenium oxide were procuredfrom S.D. Fine Chemicals, Mumbai and Arora

- Mathey, Calcutta, respecti~y. The

thermogravimetric analyses of 1:1 reaction

mixruce of StCO, and RuO, in flowing oxygen

and argon was carried on simultaneous TG/DTA

unit (SETARAM, Model TG-DSC-92-16)

employing the heating rate of 50C/min. A steady

flow rate of 2.5 Uhr was maintained during theTG runs.

In addition to TG, separate experiments were

performed for on-line monitoring of evolved

CO, in the reaction. In two separate

experimems, purified argon and oxygen were

passed over the reaction mixture placed in the

uniform temperature zone of furnace. The CO,

gas evolved in the reaction was swept by these

catrier gases inro the electrolytic cell comaining

the standardised solution of Ca(OH),. The

change in conductance of Ca(OH), solution as a

function of time was monitored on X-T

recorder. The experiments were performed at

series of temperarures in the range 600 to 800°c.

The samples in these experiments were employed

both in the form ofloose powder and pellet.

The reaction products obtained afrer the TG cun

and on heating the mixtures at differem

temperacures were characterised by Siemens

X-ray diffracromerer, Model D-500, employing

the Cu Ka ( J.. . 0.154 nm) radiarion. The

progress of the reaction was followed by

monitoring the relarive change in the intensity of

most intense lines of the producr and reactanr

phases in the recorded X-ray pattern.

Results

Thermogravimetric curves for 1:1 powderedmixture of srCo, and RuO, recordedin flowing

oxygen and argon ar 5°C/min are shown..inFig.I.

Fi~I TG","",ofU mi".""jS,cO,and&O, ""nkJinfWwinga'X'nandoxygm

From the mass loss in the TG, reaction between

the components of the mixture could be

expressed stoichiometrically as in equation-I.heat

S.cO,(s) + RuO, (s)--.srRuO,(s)+CO,(g)(I)

Identification of the product of the TG by XRD

and neurralisation ofCa(OH), solurion in which

CO, was absorbed, further confirmed rhe

stoichiometry of the reaction. It is imeresting to

note from Fig.I, that, the reacrion in oxygen was

iniriated at much lower temperarure and

proceeded much more rapidly. Also, the

temperature of the beginning of evolution of

CO, in both the cases was about 250°C lower.

compared to thar for the thermal decomposition

J 90 /-

of pure SrCO, under identical conditions. One

of rhe intriguing features of the TG curve for rhe

mixture recorded in acgon, is rhe intermediare

"ep, in Fig.l " around 950'c. This could

probably be, in oxygen atmosphere, rhe reaction

w"-S complered before rhe iniriarion of rhe

decomposirioo of pure SrCO, (~950'C),

whereas, in argon, rhe reacrion rate was slower

and reaction was not completed prior to rhe

decomposirion of pure SrCO,.

Fig.2 XRDp""=ofS,CO"RaO,hMdar60(/CinAr "d ai, "m.

The diff""nce in the reactivity of the mixtme

observed in TG experiment ca"ied our in

oxygen/air and argon g"-S atmospheres was also

evidenr in rhe isothermal experiment> followed

by X~ray diffraction. The XRD parterns of rhe

powdered mixrure heared in air and argon at

600'C for 5 hours (Fig. 2) was dearly different.

While the reaction in air was virrually complete

indiearing the absence of peaks of SrCO, and

RuO" rhe mixrure heated in argon showed

presence of these reactants. The reacrion of

powdered mixrure followed by rhe measurement

of evolved CO" employing rhe conductometric

apparatus described earlier, further confirmed the

observations made by TG and XRD. The plots

of fraction transformed (a) versus time

,,!culated from the conductivity data obrained "'

the reactioo temperarme of 800'C for the

reactioo mixrures heared in oxygen/air and argon

ace compared in Fig. 3.

m,i"nmm"

It can be seen rhar ar 800'C rhe ,'eaction in

acgon did nor pwceed beyond ~30%, bot was

almost complete for the mixrure heated in

oxygen/air. An addiriunal intere"ing parr of rhis

iovesrigation is the influence of compaction on

the reacrivity of the mixrure. The a versus time

plors obrained from rhe conductivity dara on the

powdered "rople and rhe pellet (compactcd at 8

rons/sq. inch) in oxygen atmosplmc of identical

weight at 800'C ace compared in Fig. 3. lr can

be seen rhat, in the case of powdered sample, rhe

reaction is complere in about 50 min., while in

case of pellet, rhe same was completed only cothe extenr of 70%. The difference in

rhe ,'eacrivity observed in rhe conductivity data

w"-Salso obvious fwm the XRD parrern of rhe

samples heat ([eared ar 700'C for the same

lengrh of time (5 homs). It was observed rhar

rhe cario of the "ronge" peak intensity of

SrRuO, to RuO, is much higher for the powder

compared to that for rhe pellered sample

(Fig. 4).

I 91 /--

F;g. 4 XRD pa""'" a[S,CO, . RuO, h",," at 71X1C i.

(A) pella fi"", and (B) pawdn finm

Discussion

The ,e>ults on rhe solid srare synrhe>is of

monrium curhenare pmenred hm "e idenrical

ro rhose fo, orh" alkaline eanh meral rurhenares.

namely, rhore of b"ium and calcium [4]. In

general, rhe >olid >rare reacrion fm rhe formarion

of rurhenares from rhe reacrion componenr> can

be expre"ed a> in equarion-2.hear

MCO,(,) + RuO,(5) -- MRuO3(5)+CO2 (g) (2)

Thermogravimerric curves rccorded borh in

oxygcn a> well a> argon, >how rhar rhe reacrion in

oxygen is quanrirarive and i> completed befote

the decomposirion remperarute of srCo,- The

teaction in argon is tdarivdy slow, bur

nev<[[heless, occmred ar remperarure much

lowet rhan rhat of the decomposinon of pure

srCo,. It wa> however nor complete below the

decompo>ition t""perarme of pme srCo,- The

lowering of temperatute of evolurion of CO, in

a mixrute rdative to rhat of SrCO,

decomposirion could readily be undemood on

rhe ba>is of the formation of SrRuO, in the

reaction. This may be due to more negative

hange in Gibbs energy fOr rhe reacrion in

equation-I, compared to rhat of rhe

decomposition of srCo" which could be

expre"cd a> in equarion -3.he"

SrCo, (s) -+ srO (5) + CO, (g) (3)

Since rhe fonnarion of SrRuO3 from SrCO3 and

RuO, is a >olid State reacrion, compaction wa>

expecred to incrwe rhe rare of reaction. Bur, ir

Wa>obrerved that, compaction decrwe> rhe rare.

This obrervation of reduced reacriviry of rhe

mixrure on compaction can be readily

underStood in terms of build up of CO2

pre"ure, in the pelleted sample. Such

ob,ervarions of compaction of >ample on

rhennal decompostion of metal carbonate> are

common and well documented [5].

Decomposition of SrCO, is suppre"ed

considerably if evolved CO, is not >wept away

from rhe sample. The >raganrion of evolved CO,

in rhe reacrion. in rhe compacted sample resulred

in rhe suppression of the forward reacrion. In

the case of powdered sample, the evolved CO,

can diffuse readily and get mixed up in theambienr environmenr.

Ie i> observed that rhe reaction rare leading to rbe

formation ofSrRuO, i>enhanced considerably in

the oxidising environmenr at all temperacures.

Thi> leads to the >peculation rhat, rhere musr be

a chemical reacrion involving oxygen a> one of

the reacranr species leading to rhe fOrmation of

ruthenate. Ir is known that, RuO, (5) reacts with

oxygen at high temperature to form RuO,(g) [6],

which is meraStable and disproponionate at low

temperarures. Ir i> possible rhar rhe merastable

RuO,{g) formed in rhe pr=nce of oxygen, reaCts

inStanraneously with SrCO, to form SrRuO,-

The reaction could be presenred in a following

sequence.Hear

Ru02 (s) + II,02 (g) -+ Ru03 {g)... (4)

I 92 I--

Heat

Ru03(g) + St C03 (s)-- StRu03 (s) + \/,

02 (g) + CO2 (g). . (5)

Thus, the ovmll ,ection is,he"

S,C03 (s) + Ru02 (s) --StRu03 (s) +

CO2 (g) . (6)

Conclusion

FtOm the obseevations made in this inve"igacion,

it can be coneluded that the "action involving

the symhesis of S,Ru03 ftOm S,C03 and

Ru02 should be cmied out on powdettd

mixtme in the p"sence of oxygen, since oxygen

oc" as a catalyst. The compound S,Ru03

fo,med is highly "able. Thc "udy indicates that,

thete is po"ibility of ((apping the Ru involacilised fo,m (Ru03, Ru04 ctc.) ftOm the

vme! off gas fwm the vitrification fumace,

employing the hea,ed column of S,C03 with the

supply of aic!oxygen. The volatilised species of

\Ru will "act with S£03 and will get converted

into a stable StRu03 compound.

References

1. G. Fdedlandet, j W Kennedy, E S Macias, j

M Millet., Nuel", and Radichemimy,

Wiley .Imet science, New Yo,k, 1981.

2. j.G. Shah" Investig"ions of glass and Glass

cetamics", Ph.D. Thesis, Univmity of

Mumhai 1996 and ,cfecences thettin.

3. Intemational Atomic Enetgy Agency,

'Techniques fm solidification of HLW,

Technical Repmt Se,ies No. 176, IAEA,

Vienna, 1977.

4. R.K. Mish,a, M.Sc. Thesis, Univmity of

Mumbai 1998.

5. P.O. Gam., "Thc;moanalyticaJ methods of

Invescig"ions", Academic p"", New Yo,k

(1963).

6. W.E. Bell and M. Tagami, j. Phys. Chem.,67 (1963)2432.

Ahouttheauthors .....

M, R.K. Mi,h,a, (MSe., Chern.)joined W"'te Managemmt Padl;,i", BARC, Tampu" in 1992.

He h", =eked in Pmduet Cham"",;,ation Labaeato,;n, in the filed ofX-eay diffraction, Scanning

Elea.-on MicrouopdEnn-gy Disp",ive X-cay ,tudm of diff"mt matNm foe immobilisatWn of high

level eaJi..utive liquid waste. His ",ea>'Chint""t inelude< ,tudy eelated to p""aeation and

pmp"ti" of <orneglatm of eelevance in nu,ka, te,hnology, mpp""ion of volatilization of

,"thmium, teUu,ium etc. du,ing vitrification pm"" of high Iml endioa"ive liquid W"'te.

P",ently, he is waeking in pm"" co_lIabacataci" ofW"'te Manag""mt P.uili"", Tarapue and

is mgaged in woek, eelated to monagem"'t of high level rndioa<tiveliquid w",te and low level rndio""'ve liquid waste.

~De J. G. Shah, (MS,.. Chern" 1981; Ph.D., Ch""i,try, 1996.. Univenity of Mumbai) joined

W",te Managemmt Pa,i/iti", BARC, Ta,apu" afi" grnduation from 25' batch of BARC Teaining

School He was eleputed to INE Karbhrahe, Gn-many, in 1988 foe ndvan,ed training in the

application of "'phisti,ated instrum=" like SEM/EDX, XRD uude< Indo-Gn-man bi-Iat"al

peogramme. He h", ,arned out pionming =ek in the "'velopment of matrix foe incoryacation of

high Irnel nuelm w",te in gla" in Indian nudeae pmgramme.

Me RG. Y,.tikae, (M.Sc., Ch",,-, M T"h. Chemical T"hnolagyfrom Nagpue UnivmiryJjoined

W"'te Management Division, BARC, aft" grnduation ftvm 20th batch of BARC Training School

Peesemly, he is Sup"inten"'nt. Labowoei". W"'te Managemmt Padli!i". Tampu,. and is

mpomible foe ,aerying out vaeious ",m,h and ","elopment a"ivitin eelated to nu,leae w"'te

manag"""'t and their pomble a.<loptation on plant uale apan ftvm noma! analytical,"!pon to

plant. His main pld of works inelatle. """lopm"'" and "'tailed ,har.uterifation of matrim for

immobi/i,ation of high level rndioa,tive liquid w"'te, intn-mediate level eadio.utive liquid w"'te

and managemmt of oth" typ" of mdioa,tive wa,te,. He hm contributed ,ignifi,antly in evaluation of themicol du,abi/ity

of w"'te produ'" inelnding """Iopm"'t of methods, effe" of various paeamet'" and ,imulation with "'pe" to int",;m

and final e/ipo<al He w'" a m=b" of Co-oedinated R"ea>'Ch Peogramme of In<emotional Atomic Enn-gy Agenry and

partidpated in India and alisaml

De S.R.Dhaewadkae eetieed", Head. High Tempemtuee & Solid State Chemi,try Section, Applied

Chemistry Divi,ion, BARC, Mumbai, in D".1998 aft" a distinguished "",iee of moee than ,heee

"',ude<. Du,;ng bis ","iee. he =eked extensively in the field of High T""p"atuee and Solid State

Ch""utry and eh=i,a! Thn-modynamia. He h", rstablished a _ng in<emotionally ,""oguized

group in thit aeea and ha< published moee than 125 pap'" in eeputed international joumab. The

main theust of the wack of hi, group had been in the field of Themodynami" of Nutlea! Mat"ia".

Aft" his emeemem, De Dhaewadkar, ha< taken up teaching =igument. Cueeently, he is an Honorary Pmjiuoe of

Physical Ch""istry in the Institute of Scicnee, M.mbai, wh", he is guiding the ,tuakn" for theie """ten and Ph.D.

"wen in ,hemistry. He is ","ently engaged in ",ea>'Ch ee/ated to the concrol of poU.tion ftvm industrial ejjIuen"

employing photo themieal eeactiom in pmenee of waly"'. Hi, Oth" aeea of "'mnt int""t is the development of method,

for immobili,ation and taft dispotal of high kvel n.elm W"'te. De Dhaewadkar ;, a mipient of the Netzs,h-ITAS

awaed for ou"tanding wock in Theemal AnaI)'is. He;' an ="iate of lUPAC and is a liji m""b" of """al natWnal

and in<emotWnaI Kicntifi' tomtier. He was Hon. Secretary of Indian Thmnal Anaiym Soeiny 0991-96) and i"

l'eetiMvt 0997-98). He isatpment the Viee Pmalentofthe Indian SodetyforSolidState Chemis" andAlliedScienm.

I

.. .I 94 I-----

MASS SPECTRAL STUDIES FOR THEDETERMINATION AND SPECIATION OF

ARSENIC BY GAS CHROMATOGRAPHY-

MASS SPECTROMETRY (GC-MS)S. K. Aggarwal

Fuel Chemistry DivisionBhabha Atomic Research Centre

and

R. Fitzgerald and D.A. Herold

VA Medical Center.113, San Diego, CA 92161 and Department of Pathology

University of California.San Diego, La Jolla, CA 92134, USA

Introduction

DETERMINATION OF ARSENIC

(As) is important from the point of

view of environmental and biological

pmposes. Some studi" oce "ported in lit,,"tme

[1-9J using diffecent deeivatising agen" for

p"pocing vohtile chela"s of As(III), As(V) and

m'ganic arsenicals vi2. mono methyl arsinic acid

(MMAA) and dimethyhrsinic acid (DMAA). In

continuation of om work [10J the development

of GC-MS methodology fot reace elements

determination in biological sampb, we

inve"igated two diffeeent derivatising agents Vi2.

N-tert-butyl dimethyl silyl-N-methyl-

trifluoroacetamide (MTBSTFA) with i% tert-

butyl dimethyl chlomsihne (TBDMSCI) and 4-

fluorophenylmagnesium bromide (4-FPMB) for

p"paring the chelates of As(III), As(V) and

organic arsenic vi2. dimethyl atsenic acid

(DMM), also known as cacodylic acid. Thesensitivities of th"e different modes of ionisation

vi2. electron ionisation (EI), positive chemical

ionisation (PCI) and negative chemical

ionisation (NCI) we" evaluated and mass

spema obtained wece compared to identify the

base peak of maximum intensity containing

information on As for achieving a high sensitivity

in quantitation.

Experimental

The GC-MS system used was a Finnigan MAT

4500 mass spectrometer based on quadtupole

mass analyser and a Finnigan AlOOS

Autosamplee. Peefluorotributylamine (PFTBA)

was used to °ptimi2e tuning for EI, PCI and

NCI. Methane was used as the "agent gas for

pC! and NCI at an ioni2er pressu" ofO.80IO.05

tort and an analysee p"ssu" of 1.4 x 10' torc.

The EI, pC! and NCI tunings we" optimized at

m/z 100 and 502; 219 and 414; and 414 and

613, "spectively. After tuning, scans wece

obtained fro;'" m/z 50 to 650 in 2 seconds. 70

eV elemons we" used in the EI, PCI and NCI

modes.

The As-chela"s weee p"pared using MTBSTFA

and 4-FPMB in independent expetimon" using

aqueous solution of As(III) as Asp, in 10%

HNO" methanolic solution of As(V) as Asp,

and methanolic solution of DMAA. Fir", the

ten-butyl dimethyl silyl (t-BDMS) deeivatives of

J 95 I--

inorganic and organic a"enicals were prepared

by rrearing As,O,. As,O, and DMAA directlywith MTBSTFA. Second, the r-BDMS

dedv"ives were prepared by first synthesi,ing rhe

pyrrolidine dirhiocarbamares of As(Ill), As(V)

and DMAA. The wluene solutions containing

tbese derivatives were evaporated to complete

dryness at 40'C under a steady srream of", gas.

The dried residues were dissolved in 200 IfL of

ethyl acetate and 50 IfL of MTBSTFA was added

and used for preparing a"enic derivatives.

The fluorophenyl derivatives of As(Ill), As(V)

and DMAA wete synthesized by first preparing

tbeir respective pyrrolidine dirhiocarbamates

followed by treating witb 8-10 drops ofGtignard

reagent (4-FPMB) [10J.

One mL of rhe metal chelate, containing 200 ro

400 ng of As, was injected into rhe GC in the

splitless mode using autosampler. A IS m x 0.32

mm i.d. cross-linked dimethylpolysiloxane (DB-

1) capillary colwnn with a 0.25 Ifm film

thickness was used in these studies. Ultra high

purity helium (99.999%) was the carrier gas.

Results and Discussion

A typical EI mass spectrum of As(FC6H4)3 isshown in Fig. 1. The fragmentation patternsobserved with EI were interpreted through acombination of PCI and EI mass spectra. It was

observed rhat rhe t-BDMS derivatives of As

eluted at lower temperature than rhe flurophenyl

derivatives and showed a simpler and deaner E!

mass spectra. From the mass spectra cecorded ondifferent arsenic chelates mentioned above, it was

observed that rhe derivatives of As(III) or As(V)

formed directly with MTBSTFA were

(C,H"Si),AsO, irrespective of As(III) or As(V)

taken initially. With DMAA, the derivatisation

resulted in the formation of (C,H"Si),AsO, with

small amountS of (C,H"Si),AsO" with each

compound showing distinct elution peak in GC-MS. When derivatisation with MTBSTFA was

performed by first preparing the pyrrolidine

dithiocarbamates of As(Ill), As(V) or DMAA,

the derivative formed was (C,H"Si),AsO,. The

4-FPMB derivatised inorganic as well as organic

arsenicals to As(FC,H.), independent of rhe

starring form of As.

Among the tbree different modes of ionisation

used, EI was found to give the highest sensitiviry

for As quantitation whereas NCI was found to be

rhe least sensitive for botb rhe derivatives of As.

For example, the relative sensitivity values forEIIPCI were found ro be 6, 12 and 2,

respectively, for direct dervarisation with

MTBSTFA, derivarisa.ion with MTBSTFA

tbrough pyrrolidine dirhiocarbarnates andderivarisation witb 4-FPMB.

I 96 /--

Conclusion

The remits obtained dearly ,how that fot the

""'y of ;" by GC-MS, detivati"tion withMTBSTFA or with 4-FPMB through

pyrrolidine dithiocatbamate, can be employed.Ditect d«ivatimion of ;" with MTBSTFA

would not be udul in teal-life "mples becau,e

thi, would demand the quantitative dissolution

of ;"(III) and ;"(V) in an otganic solvent

miscible with MTBSTFA The t-BDMS

derivatives of ;" formed with MTBSTFA do not

tequired sHation of the GC column. The final

choice of the detivatising agent would, howevet,

depend upon the quantitative and reproducible

tecovery of ;" when carricd through the entite

procedure. Since ;" is a mono-isotopic element,anothet element as a witable internal standatd or

another external standatd would be requited fot

;" quantitation by GC-MS.

References

1. W.C. Burrs, W.T. Rainey Jt., Anal. Chern.43 (197J) 538.

2. F.T. Henry, T.M. Thorpe, J. Chromatogr.166 (1978) 577.

3. E.H. Daughttey Jr., AW. Fitchett, P.Mushak, Anal. Chim. Acta 79 (1975) 199.

4. T.P. Mawhinney, J. Chromatogr. 257(1983) 37.

5. H.D. Wam, D. Cameron, Proc. of 42ndASMS Conference on M",s Spectrometry

and Allied Topics, Chicago, 1L, May 1994,p. 271 (1994).

6. D. Cameron, T.Brozovich-Fotd, H. Watts,

J. Wingh, Paper NO. WPF 163, ptesentedar 43td ASMA Conference on Mass

Spemometry and Allied Topics, Arlanta,GA, May 26-30,1995.

7. B. Beckermann, Anal. Chim. Acta 135

(1982) 77.8. S. Fukui, T. Hitayama, M. Nohara, Y.

Sakagami,Talanta 30 (1983) 89.9. J.-J. Yu, CM. Wai, Anal. Chern. 63 (1991)

842.

10. S.K. Aggarwal, M. Kinter, R.L. Fitzgerald,D.A Herold, Crit. Rev. in Clin. Lab.Sci. 31(1994)

tbe Second Best'P;;perPrize in ISMAS Symposiumqn'.9, 1999 held at IICT, Hyderabad

About the author. .

T"mbay, Mombai H,

h;, B.Se. (Horn.) fram Go,"Nanak D" Unin",iry,Amri"m, in 1972 whh two

Gald M,da", h, joinrd th, 16'

Batch of R;J.RC Training Se.hoolin 1972 and ",ri"d th, Homi

Bhabha Aw"d H, did hi> Ph.D. from Bambay Unin",iry

in 1980. H, warkrd at th, Unin",iry af Antw,'P' Br/giam,

on Spmk Sou", Mat> Spwam,try (SSMS) for 6 montht

during 1982-83. H, had hi> Part-M"aral "aining (1987-89) in GC-MS for tra" ,umm" dr,,~ination in bialogical

rampkt at th, Unin",iry of Virginia HraUh Srim'" Cm"',USA. Hri,ocoaatharaf

300 pablicatiom whi,h inr/adr 100 "ti,kt"pa"d jauma". Dr Agga~al h~ partidpa"d

""'01 in"mational and natianal ,"nft"n", and indijf"'" in"mational intmomp,,;,on ,xp"imm" on TlMSandalphatp"",mrtry ofPa and U H, it a ;p,dal;,t in th,fi,1d of atomi, matt ;p'mom"ry and alpha;p""ammy ondit in""",d in ondaUtatomi, m"'t ;p"",mrtrit ",hniqo".Hi, nth"""" ofint""t inr/odr tk"r"h,mi;try a;d ralnmt""a,,ion. H, "rord ISMAS '" a S"""ry during 1992-

Vi"-P",idr,, (HQ) of ISMAS H,Ex,roti" Commit'" of In"mational

Conftrm". H, hM oi;i"d t",ralin Am"ica, Ea"p' and AUt"alia '" an ,xp"t '"

wr/IMjordrb",ingk,tum. H,i,"",ofth"dilO"afth",book and i; a r"ogo;"d Ph.D. Goidr of th, MombaiUni,,"iry.

. . .I 97 I-

ISOTOPE RATIO MEASUREMENTS FORPLUTONIUM IN ISOTOPIC REFERENCEMATERIALS BY THERMAL IONISATIONMASS SPECTROMETRY (TIMS) USING

TOTAL EVAPORATION TECHNIQUE

S.K. AggarwalFuel Chemistry Division

Bhabha Atomic Research Centre

and

R. Fiedler and S. Deron

Safeguards Analytical Laboratory

Seibersdort, Vienna, Austria

Introduction

TOTAL EVAPORATION METHOD-

ology is expected to ei"umvent the

ubiquitous pcoblem of iwtope

fnctionation duting isotope ntia measueements

by TIMS. hutope fnetion"ion has, in fact, bem

plaguing the ovmll accuney achienble in the

deteemination of Pu and U isotope mios andeoneemmion in dissolvet solution of itndi"ed

fuel and in othee complex mattiees. Hence, it

was of imeeest to veeify expeeimenrally and

deteemine, if any, the "sidual isotope

ftaetionation factot commonly called", B-faetot

Ot K-factot. These studies wete petfOtmed on

MAT-I (Pu) mass specttometee using diffmm

iwropic "feeenee matetial, of Pu available at

SAL and obtained fcom IRMM, Belgium; NBL,USAandAEA, UK.

Experimental

Difbent isotOpic tefetenee matetials of Pu

(IRMM-290 seties, AI, BI, CI, FI and Gl)

ptepated at IRlVIM, Belgium by mixing highly

emiehed ""l'uO, and "'PuO" and ecnified with

ovmll unecnainry of 0.01 % at bettet fot

"'1'0/"'1'0 isotope ntios weee used. In addition,

the orlm isotOpic "fetenee mateeials of I'u

avaibble ftOm IRMM, Belgium (CBNM-047A);

NBL, USA (CRM-144, NBL-128, NBS-947)

and fcom AEA, HatWelJ, UK (UKPu5) wm also

used.

Replicate mass spectcommie analyses (15 ro 25

filament loadings) wm petfonned on each of thc

isotopic "beoce matetial usmg the

Measmemem Pcoroeol (MI' 16) fot total

enpontion technique generally osed " SAL.

The pcotoeol was based on heating the ionisation

fibmem ro a tempeeatu" co([esponding ro a

signal of 275 mV fOt "'Re' ro ensuee nearly same

ionisation filament tempetatme in diffmm mass

spectcomcttie analyses. Then the sample filament

was heated slowly at pte-defined nte (50

mAlstep) ro a tempet"u" SO" ro ger the som of

the ion co([em of all the isotopes of Pu

eouesponding to about 40 mV. After achieving

this pte-set signal sttength, the heating of the

198 I-

sample filamem was cominued ar one of

rhe rhree defined heating rates (50 mNstep,

10 mA/srep or 1 mNstep) depending upon rhe

signal strengrh; and rhe ion currem inregcarion

was performed. The imegrarion of rhe ion

currem was cominued umil rhe Pu' signal

srcength fell below a pre-defined value (abour 40

mY). This usually involved rhe hearing of rhe

sample filament to a currem of abour 6.2 A

which w", also pre-defined in rhe measuremenr

Results and Discussion

prorocol and mainraining ir ar this value untilthe sample waspmtically exhausted.

The results obtained from rhe replicare m",s

sperrromercic analyses of differenr isotopic

reference materials of Pu are given in Table 1. A

number of interesting obsecvarions were made

during rhe mass spertromercic analyses", well "'

during data evaluarion.

Table 1: Comparison of the certified and exp«imentallydetermined isotope rarios in Pu reference marerials

Code(Atom Ratio)IRMM-290-Al

(242/239)lRMM-290-Fl

(242/239)IRMM-290-Gl

(242/239)lRMM-290-BI

(242/239)lRMM-290-CI

(242/239)CBNM-047-A

(244/239)NBL-CRM-144

(240/239)NBL-CRM-144

(242/239)NBL-CRM-144

(244/239)

'Measured in November 1997

"Replicate mass sperrromerric analyses perfmmed

01;;;;;;00'Her

0.97545(0.025%)0.099483(0.025%)9.87088(0.025%)0.432996(0.013%)2.14423

(0.0058%)0.772611(0.043%)15.11086(0.016%)

.. Bfactorlat~m (%)(l'cr)

,0.0051,,0.0040[25]"

0.0144f 0.0043[19]

0.0124 f 0.0042

[24]0.0046 f 0.0037

[2310.0071 IO.0036

[201HO

[16}

199 I-

In some cases, when the total number of scans

colleeted duting the measUtement we« low (say

50) compa«d to the usual nUtllbet of scans

=ging ftOm 100 to 250, the experimen<ally

measu«d isotope ratios (242/239, 244/239) we«

higher compared to the usually obtained ratio.The less number of scans are observed in a few

cases, probably due to improper setting of the

sample magazine! extraCtion lenses focus during

computer conttOlled automated mass

specuomecri< analysis. DUting the data

acquisition for UKPu5 sample, it was observed

that sufficien< Pu' signal is obtained always

without heating the sample filament. In other

isotopic «ference materials, data collection

started only after heating the sample filamen< to

appreciable «mperatu« (filament curren< of 1.5-

1.8A). This difference in the analytical

conditions could lead to different B factOt, if

any, during the analyses. A compatison of the

experimen<al data with the certified values

indicates that the B faetor determined can be

related to the origin of the certified «f",nce

material. For example, the B-faetors derermined

using the isotope ratios ""puimpu ate negative

while those derermined using "'Puimpu and

'Mpui"'Pu isotope rarios ate positive in case of

UKPu3 and UKPu5 (i.e. p«pa«d in UK). For

the «fe«nce materials NBS-947, CRM-I44 and

NBL-128 (i.e. p«pa«d in USA), the B-faetors

determined are always negative irrespective of the

iwtope ratio used. For the isotopic ref",nce

materials p"pa«d in IRMM, Belgium from

oxides, the B-faerors are very small (less than

0.02% per mass unit) but these lie in both thedi««ions.

From the experimen<aI data on "'Pu/mPu and

"'pu/mpu isotope ratios ofCRM-I44, NBL-128

and IRMM-290 series reference materials, it can

be stated that using total evaporation and the

existing isotopic «ference materials, the B-faetor

per mass unit is less than 0.02%. This is in

contrast to the studies performed at SAL using

the uranium isotopic reference materials when noB-faetar was observed. This corrobora«s the

studies published from the laboracory in

TtOmbay showing that the B-faetors for U andPu arc different and that the B-factor for Pu is

higher than that for U.

Nuclides

240/239

Table 2: Mean precision values (Pu isotope ratio measurements in reference materials)

Mean piedsion (%)"

242/239

Isotope ratio value0.240.9615.120.0150.0990.430.971.001.03H49.8621.020340.777.99

244/239

Predsion(%)~0.0140.0160.0510.0250.0130.025

0.012

0.024

0.043O.O;;!t

0.035

I 100 J--

Thece i, need to have mme more new i,otopic

rebence matetiab ofPu with cenificd "'Pu/"'Pu

as well" "'Pu/""Pu imtope catios to confitm theexistence of small but meamtable mass

di"timination effects even in total evapocation

measurements and also to teso/vc the discrepancy

of conventionally expected negative B-factot (as

obsecved in we of CRM-144, NBL-128,

IRMM-290/Al) versus pmitive B-factot ("

obsecved ftOm IRMM-290/Bl, Cl, Fl, Gl).

DOting the data evah"tion ftOm replicate mass

spccttOmwic analyses, it was obseeved, as ,hown

in Table 2, that the memal reptOducibility was

dcpendent on the mass diffmnce bctween the

iwtopes measmed exccpt foe CRM-144. These

valoes tangcd ftOm 0.010-0.020%, 0.020-0.030% and 0.040-0.045% foe "'pu/""pu,

"'Pu/""pu and ""'Pu/"'Pu isotope tatio"

respectively. This is anothet indication that

inspite of uswg the total evapotation

mcthodology, thete is ,mall ,'esidual B- factot

present fot Pu and this is affecting the

"ptOducibility of the isotope tatios as a function

of the ma,s diffmnce between the two isotopes

measured.

It was also of interest to study the influence of

staning ion cmrent ptim to integcation, on the

measmement of isotope catios. Fot this putpose,

the rebence matetials CRM 144 and IRMM

290/Al wete analysed using diffetent ion

intemities (20 to 200 x 10'" A) at the stan of the

measmement. Replicate m"s spectwmettic

analyses wm cacried OU( fm the two standatds at

font diffetent values of the staning ion intemity.

Measmements at SAL are nmmally petfotmed

with a statting cunent of 40 x 10" A. The Pu

isotope tatios detetmined ftOm the two rehence

matetials are given in Table 3. Thete is no

significant difhence in the isotope catios

measuted using vatying values of the staning ioncmtent and moreovet, thm is no cleat "end

obsecved foe the dependence of isotope tatios on

the staning ion cumnt. This ,howed that thete

is no additional bias intmduced in isotope tatio

mcasmements by the total evapotation method.

Table 3, Effect of changing sum ion cumnt parametet in data

collection pmtocol of total evapotation foe Po isotope tatio detetmination

Smn ion cumnt

20mV

40mV

'Ccnified value

'Replicate mass speen-ometic analyses

J 101 I-:-

Conclusion contribution of different species produced during

evaporation and ionisation in a surface ioni",ion

source. Th"e.srudi" will furrher mengthen the

data produced hy TIMS and will hc very useful

in improving thc precision (external) and

accuracy values to better than 0.1% in thc nextmillennium.

The above studies emphasise the need of mme

isotopic reference matecials foc plutonium to

confirm that the isotopic fraerionation effects are

completely eliminated using total evaporation

and ion current integcation methodology.

Further, it is necessary to examine the percentage

This paper was awar'fied thi Second Be;; Paper Prize}~n fiMAs Symposium on MassSpectrometry, December 7-'), 1')')') held at HCr, Hyderabad

About th, auth" ..

D,Sumh Kuma>Agga~al, born in 1953, ;,cu",ntly Head, Man Sp,,"om"'Y Swion ofth,

Fu,1 Ch,mi<t'Y Div;,ion, BARe. He ""ivd hi, B.Sc. (Hom.) fiom Gum Nanak D"

Univmiry, Am,it;ar, in 1972 with two Gold MuM,;. H, join,d th, 10> Batch of BARC

Training School in 1972 and ""ived ch, Homi Bhabha Awa,d H, did hi, Ph.D fiom

Bombay Univmiry in 1980. H, wvckd at ch, Univmiry of Antw"p, Belgium, '" Spack

Souu, M<li' Spwmm"'Y (SSMS) ft' 6 month, du,ing 1982-83. H, had hi, P"t-doctoral

"aining (1987-89) in GC-MS ft' "a" ,I,mmt; dete,mination in biological ;amp'" at th,

Univmiry of Vi'ginia Health Scim'" Cmt", USA. H, i, a coamh" of 300 "'mtijic

pub/ication; which include 100 actic", publirh,d in "puted Joumak D, Agga~al h<li

participated in "',,"I international and nadona/confi,m", and in difJmnt international int",ompariron "p,rimmtr

on TIMS and alpha np"",m,try of Pu and U. H, i, a 'puiali<t in th, fi,1d of atomic man 'p,,"om,,'Y and alpha

'pec",m,try and;, intm'ted in variom atomic m<li' 'pec",mmic technique;. Hi, oth" area, of int",rt include

"'",och,m;,try and rolvmt extraction. H, ",vd ISMAS <li a Secma'Y during 1992-1997 and i, pmmtly, Vi,,-

Pmident (HQ) of ISMAS. H, "pmmt; India in th, Executive Committe, of International M<li' Spec"om",i,

Conjicm". H, ha; v"ited "","I countrie; in America, Eump' and A"",alia a; an expect a; weU a; ft' deliv"ing

I"tum. He it on, ofth, ,ditor; ofthm book, and i, a ,ecogni,d Ph.D. Guid, ofth, Mumbai Univmiry.

. 8 .

I 102 I---

VACUUM DECOMPOSITION PATTERNOF FERROUS AMMONIUM

SULPHATE - A QUADRUPOLE MASSSPECTROMETRIC STUDY

Y. Sesha Sayi, P.S. Shankaran, C.S. Yadav. G.C. Chhapru and K.L.RamakumarFuel Chemistry ~ivision

Bhabha Atomic Research Centre

Introduction

DURING OUR AITEMPTS TO

develop an analytical technique fo, the

dete,mination of ,ulphm by vacuum

combu"ion extraction-quadrupole ma"

'pectromwy [1], p,eliminary expetimen" we'e

carried out by taking fmom ammonium ,ulphatc

as ,efereoce matetial. Measmemcnt of

compo,ition of gase' evolved by quadrupole mas,

'pectrometry ,evealed that apart from SO" gase'

N,o. NO and NO, we,e ob,erved. But no peak

due to ammonia NH, could bc detected. With a

view to undemanding the decompo,ition

behaviou, of fmom ammonium mlphate,

detailed inve"igatiom we'e cartied out. Imtead of

adapting the conventional thetmal analy,i,

tecbnique,. quadrupole ma" 'pewometry has

been employed ro monitot the product gas'"

formed. The pre,ent papet gi= a brief account of

our ob,ervatiom on the decomp",ition of ferrou,

ammonium ,ulphate under vacuum at

temperarur", 600°C to IO40°c.

Experimental

Equipment

The hot vacuum extracrion-quadrupole mas,

'pecrromerer employed for the pmenr "udies hasbeen desctibedin om paper [I]

Chemical,

Analytical gradc fmom ammonium ,ulphate

Methodology

Known amount of the ,"mple was loaded into the

quartz tube and the entire 'y"em was evacuated

ro 10' mbaL The ,"mple was then heatd at the

required tcmpcratme for 30 minutc, under 'tatic

vacuum conditiom and the gasc, released werc

extracted into a known volume. The gas pre,,",e

and the compo,ition were thcn determined by

online diffetential oil manomctcr and quadrupole

mas, 'perromete, re'pectively.

Results and Discussion

The ftagmentation pattern, of N,o, NO and

NO, ate taken from the ma" ,pectrometer',

library. Fractional abundance, of the patent

molecular peaks at mlz " 30, 44 and 46

corre'ponding to NO, N,o. and NO,

te'pectively we,e calculated from the rcfetence

'pecrra. The,e were in turn mcd to measure thc

intemitie, of the,e mas' peaks obtained in the

,"mple analy,i,. A rypical mas, 'pewa obtained i,

given in Figure 1. A 'eparate expetiment was

carried out ro record the "blank" mas, 'pectrum.The intemitie, at different mlz value, were

corrected for the blank. From the intemitie, of rhe

I 103 I--

Fig. I. M",'pmrnmoJg"""u"dji,md",kmmpmiti""JF",omAmmoniomSulph",

sacious fmgmemarion peah, total intensity of the

"spenive pacem mohula, peak is computed.

The ,elative imensici,s of ",ious nitcogen oxides

nomnlis,d with 'espen to Np we,e calculated

and given in Table 1.

Table 1 , Relative intensities of nit;agenoxides

horn the T ahle, it can be seen that NO fmmation

inmases with tempentme up to 800"C, and

above this tempentme it decomposes which is in

ageeemem with the lit"'tme data [2]. Bm at all

tempentmes Np is the peedominam species

conteary to its reponed behaviom [2]. On the

orhe, hand At 1O40"C small quantity of NO, is

observed. However, both Np and NO, ace

cxpecred to decompose at these temperarmes. No

ma>; peak due to NH, could be detected ar all

temperatures investigated. To subsramiate the

obsemtions, it is desicable to carry out funher

work to study rhe decomposition of niteates and

I I04 I---

TEMPERATURE ("C) NP,NO,' NO

600 1 , 0 , 0.8

700 I , 0 : 2.0

800 1 , 0 , 3.1

1040 1 :0.01: 0

mmonium "],, on the,e line, in vaeuum, ait and

limited oxygen supply,

Nitwgen content in the sample was ,]so

compmed fwm the concenmrion of N,o and

NO, and it was found ro be well within I 5% of

the expected value from i" sroichiomeuy.

Acknowledgement

The amho" ate thankful to DL V. Venugop,],

Head, Fuel Chemistry Division, fot his keen

ime<eH and continuous encou'"gement in thiswmk.

References

I. Y. Se,ha Sayi ct.,]., Papet no. ICT-4, ISMAS

Sympo,ium (1999).

2. H.D. Gehani and S.M. P"ekh, Modern

Inotganic Chemistry, Educational

Publishe",1970.

Ab"tth,autIMs..

Dr Ydku, S,;ha Sayi jaind BARC in 1978 aft" ablaining MSc. (Physical Chanistry in 1972) and

Ph.D (1977) flam S,i Vmkat,;wata Uniamity. H, is mainly invalv,d in chanical 'f.ality canltal vi

nucI,", JUds. He has au, cam,d aut sam, th,rmadynamic studi,; an catbide JU'"'

M, PS Shankamn cample"d past gmduatian in Phy;ical Ch,mutry from Bambay Uniamity in 1979.

He h mainly invalaed in the ch,mical quality canltal and thtmwdynamic studi" al nucleat JUe",

M, c.s. Yadavabtain,dhisMSc. inlna>ganic Chtmistryflam Bambay Uniamityin 1979. H'jaind

BARC in 1982. His h mainly invalvd in the ch,mical quality canltal and thamadynamic studi" al

nucleat JUeh.

Mr G.c. Chhapro jaintd BARC aft"paduatingin Chanistryflam Bambay Uniamity (1973). Ht is

mainly invalad in the chtmical quality canltal and thamadynamic studi,; al nucleat JUth.

D, KL. Ramakumat, ftdd al in"mt include dmlapmmt al mtthadalagi" fa' ltaCt analysis aad"patatian p"Ctdum.

. .. .

I 105I--

X-RAY AND THERMAL STUDIES ONTI-Pu-Mo-O SYSTEM

N.D.Dahale, S.K. Sali, K.L.Chawla, R.Prasad and V.VenugopalFuel Chemistry Division

Bhabha Atomic Research Centre

Abstract

The quaternary Tl-Pu-Mu-O system wa' investigated for the first time and preparation and

characterisation of new compound namely TI,Pu{MoO,j, wo., carried out. The compound wo.,

indexed on orthorhombic systems. PoO, and MoO, were mixed in i:2 molar ratio and heated in

platinum boat at 6O0"C to get PuIMoO,j,. TI,MoO, and PoIMaO,j, were mixed in i:i molarratio and heated at 500"c.

PuIMoO,j, + TI,MoO,

500"C lair)

3> TI,PuIMoO,!J

XRD pattern of T!,PulMoOo!, could be indexed on urtbnrhombic sy,tem., with cell

parameters a ~ 10.056A , b ~ 24.893 A. Compound T!,PulMoOo!,, was heated up to1200"C in Mettler Thermal Analy,er in air at the rate of iO"C\ min. Simultaneous TG,

DTA and DTG were rec",'ded TG did not show any weight change up to 700"c. The DTA

curve of this compound showed endothermic peak at 565"C due to melting of the

compound This was confirmed by physical verification of the sample, X-ray diffraction

pattern before and melting were identical indicating TI,PuIMoO,!J melts congruently. While

on controlled cooling, sharp endothermic peak at 460"C was due crystallisotion, Isothermal

heating at i200"C gave the product, which wa.' identified by XRD as PuO, .

1106 I-

Ab,ut tbe Autb",

~.

After obtaining MS" in Phy,ical Chemistry from Poona univmity in 1979. Mr

N.D.Dahale joined BARC in 1981. His main area of wea"h has been preparation of new

compounds by solid "ate teactions and their charaet"isation by X-ray and thermal methods.

He i, a&o involved in development of X-my fluotescenee speetmmetric methods of elemental

analysi,. He has published several papm in international journa& and symposia.

Dr S.KSali completed his MSc degree in Physical Chemistry from Poona University in

1981 and joined Fuel Chemistry Division in 1983. He obtained his Ph.D. degree from

Bombay Univmity in 1997 Hisfield oftesearch IS thermochemical investigation of actinides.

Mr Rajendm Prasad. joined BARC after obtaining M.Sc. in Chemistry from Allahabad

Univmity (1966). He isfrom the J(f' batch ofBARC Training School. His area of intete"

is thermodynamics of nudear materiak

Dr Ie Venugopal i, the Head of Fuel Chemistry Division. BARe. He is from 14' batch of

BARC Training S,'hool. He IS a Ph.D. guide of Mumbai Univmity. H,s main area of

intere" is thermodynamics of nudear materiak He has mote than 180 publications in

teputed international journak

-.,

. . .

I 107I'-

NORMALIZED DZIDT WAVEFORMFOR EASY ASSESSMENT OFPERIPHERAL BLOOD FLOW

Jagrul! Chheda and Nagesh ChauguleFinal Year Students, B.E. (Biomedical Engineering)

Thadomal Shahani Engineering College. Bandra (WI, Mumbai

andT,S. Ananlhakrishnan, J. Prakash Babu and G.D.Jindal

Guides from Electronics Division

Bhabha Atomic Research Centre

Abstract

A new waveform cal/ed the normalized impedance plethy.smographic waveform has heen introduced

for the easy assessment of peripheral bloodflow. This wavefurm is obtained by taking the natural

logarithm of the instantaneoa.s impedance of the body ."gment and then differentiating with fe.spect

to time. The waveform thus obtained ha.' its amplitude pmportionalto blood flaw index in the body

segment. This waveform gim an odvantage to the clinician for e",y and quick interpretation of the

data in the manner similar to that of electrocardiography.

Introduction

Impedance Plethysmog;aphy was inuoduccd by

Jan Nyboer as fur back as 1940 fot the

assessment of central and peeipheral blood flow.

He proposed parallel conducror theory for the

estimation of peripheral blood flow in a given

body segment and couelated the impedance

plethysmographic estimates with the actual flow

in in-vitro expeeiments and demonsuated high

degree of couelation (6). According to this

theory, the change in blood volume <1Z is given

by the following relationship.

<1Y='Pb xL'!Zo'x<lZ .

where Pb is the <esistivity of the blood (a-cm),

L is the length of the body segment (cm), and Zo

is the basal impedance of the body segment.

Equation I was fuuher simplified for the

estimation of peripheeal blood flow by

mbstituting Y in place of PbxL'/Zo (1.5).

<1YIV= -<1Z/Zo .. (2)

This equation was used to compute blood flow

in the limb segment pee 100 cm' of body tissue

per minute by substituting Y=lOOcm' and

measu<ed values of Zo and <1Z.

..(1)

<1Z could be measliCed by the Nyboec's back

projection method (6), Kubicek's forwacd slope

method (4) 0' ,he venous occlusion p,inciple (5).The fo,me, rwo methods suff" from d,.wback

of an wo, in fwnt pwjecrion or the extension of

forward slope. The venous occlusion principle

had the advantage of giving enhanced signal as

<1Z was integrated over a long interval of rime in

jlO8r

commt to the othee tWo method" (which

me",me t,Z foc one caediac cycle). Howevee,

venous occlusion peinciple method al,o ,u£feeed

ftOm the following dcawbach

1. Thi, method could be used to "timate the

peeiphecal blood flow only in the discol

"gmen" of the "teemitie, due to

application of a toumiquee in the ptOximal

pact of the limb. Thu, it wa, po"ible todetect the deceeased actetial blood flow in the

limb but it w", not po"ible to specifY

apptoximate anatomical location of theacteeial block.

2. Due to application of toumiquet, themethod became off line and it was not

po"ible to ""'" peeipheml blood flow inceal time and thedoce tendeeed the method

unsuitable foc monitoring.

In patients with deep vein thtOmbo,is oc patients

having oedema in the cmemities due to othee

pathological conditiom mch a, Iymphangities,

cenal fail me, congestive caediac failme, eec., the

amplitude of the signal eecoeded w", very low

and could lead to a false diagno,is of peeiphecalatmial occlmive di,we.

In view of the above, Paculkae et. al. (7) med

dZ/dt wavefoem foc the mea,ueemem of t,Z pee

catdiac cycle in ehe mannee ,imilae to that med

by Kubicek et al. 0 to "timaee the moke output.

Accoedingly, they computed blood flow in ml

pee 1000 cm' of body eisme pee caediac cycle

commonly known", Blood Flow Index (BFI)

ftOm the following eelatiomhip:

BFI~IOOOxA,xToIZo .

whece A, i, the amplitude and T, i, the dmation

of the 'ystolic wave of the dZ/dt wavefocm.

The BFI thu, obtained w", found to dem",e

significanrly at and below the 'ight of arterial

occlusion in an exteemiey. Jindal et al. (2)

employed Paculkac', method and inv"tigated

211 patient' with peeiphecal arterial occlmive

di"",,,. In addition to Blood Flow Index, they

inttOduced diffeeential pube activol time to

diffeeemiaee betWeen the nanowiog of an aneey

and an acteeial block. Compatiwn of tlieie data

with angiogeaphic ob"cvatiom cevealed the

"n,itiviey and specificity of thi, technique to be

97.5% and 98.1% e"pectively foe the diagnosis

of peeiphecal acteeial occlu,ive di"",,,.

Thi, method appeaced to be of choice foc the

non-inmive diagno,i, of peeiphecal acteeial

occlusive di,wes. Howevee the vimal impenion

of the wavefmm withom taking cognizance of

thc value of ba,,1 impedance Z, could mdead

the clinician abom the "timate of peeiphecal

blood flow. The inteepe,,"tion of data had

theeefoec to wait till the BFI is calculated and

theeefore the method did not appear ,uitable for

rhe long teem monitocing of the patient'. With

thi, in view we undectook the development of

nmmalizing the dZ/de wavefmm with e"pect to

the base impedance value '0 that the amplitude

of thi, new wavefoem is cepe"entative of the

Blood Flow Index in the body "gment. The

peinciple and method employed foe obrainingthi, new wavefmm and the eemlt, obtained wirh

thi, new wavefoem ate peesented in this papee.

Materials and Methods

.. (3)

The noemalization of the dZ/dt wavefmm ha,

been obtained by ming Impedance Cardio-mogcaph system developed at BARe. The'implified block diagcam of impedance mdio-vasogeaphi,", ,hown in Fig.1. It compels" of a

,ine wave cmeem 'omce' which- p""" umselectable ,ine wave cmeem of comtam

amplitude wieh 50Hz feequency thtOugh thebody "gmem undee inveHigation. The voltage,ignal developed along ehe cmeem path i, "med

by "nsing electcodes. Thi, ,ignal i, amplifiedfilreeed and bufbed ro obtain a voltage 'igoalZ that i, proponiona! to the inmntaneom

J 109 I-

ToPC MUx

electtical impedance of the body oegment und«

inveStigation. Thi, Z ,ignal i, uoed to obtain

~Z(t) by ",ing a diffetential amplifi« and Zo

,ignal obtained fcom pc. Z i, abo uoed to obmin

dZ/dt signal by using an electronic diffetentiatm.

The signal NdZ/dt (1/Z , dZ/dt) i, obtained by

u,ing a logatithmic amplifiet and a diffetentiatot.

The Z ,ignal i, fed to a logatithmic amplifiet to

obtain the natmal logadthm of Z (In Z). The

ompm of log amplifiet is fed to an electronicdiffetentiatot to obtain notmalired dZ/dt.

Anyone of the thtee outputs ~Z (t), dZ/dt, and

NdZ/dt i, selected by PC with the help of

multiplexer. The output of the multiplexet i,

digitized and oenr to PC fot the pcoc",ing and

display of the output waveform.

Results and Discussion

Fig.2 (a) ,how, the dZ/dt wavefotms at diffetent

locations at the lowet extremity of a nmmal

subject. As can be seen from the figure the dZ/dt

wavefmm varies ,ignificanrly from location to

location. This vatiation in ptinciple can be dueto,

Fig. I

I. Non-unifmmity in the atea of ctOss-section

in an extremity.

2. Vatiation in tissue composition ftOm

location to location in an extremity.3. Presence of an arterial occlusion in the

ptoximal part of the body oegment.

The vatiation in amplitude of dZ/dt wavefotm

due to ti>sue composition variation or artetial

occlu,ion i, proportionally teflected in value of

Blood Flow Index (BFI). Hence thi, vatiation i,

of importance to the clinician fot the Study of

petiph«al haemodynami"". But the variation in

the amplitude of dZ/dt waveform due to non-

unifotmity in area of ctOss-section of the limb is

alway' accompanied with proportional variation

in the value of the bml impedance. Becauoe of

thi, it does not cauoe any ,ignificant change in

the value of BF!. As seen ftOm Fig.2 (a) the value

of dZ/dt i, compatatively great« in the calf

region as the value of Zo is more in the calf

region while the value of dZ/dt is comparatively

les, at thigh, as the value of Z. at thigh region is

less. Thus the clinician will not be able to give

the diagno,i, juSt by looking at the g;aph,. Fig.

2(b) gives the recmding of NdZ/dt waveform

J 110 I--

Fig. 2

1 III I---

in same subject from corresponding locations. As

can be seen &om Fig.2 (b) the variation in the

amplirude of NdZldr is nearly independem of

the basal impedance value and therefore ir is clear

that the amplitude of NdZ/dr is proportional ro

BF!. Thus it directly reflecrs the haemodynamic

v..-iarions. A clinician can therefore have just a

look ar the waveforms and imerprer in a mannersimilar ro thar of ECG records.

To conclude, the amplitude of dZ/dr waveform

depends on blood flow index in the body

segment and also on the basal impedance value

of the segmem being diagnosed. Therefore the

value of the basal impedance had ro be taken imo

conside",ion while performing the diagnosis. In

conrmr ro rhis the amplitude of NxdZ/dt

waveform is independent of the basal impedance

value and is directly rclated ro the blood flow

index in the limb segmem. The clinician can

rhus give the diagnosis just by visual inspectionof the waveforms.

Acknowledgement

The authors express rheir gratitude ro DL S.K.

Kar..-ia, Head, Elecrronics Division, BARC, for

his cominous guidance and support for rhiswork. The fim tWo amho", arc thankful ro Ms.

Mita Bhowmick, Inch"ge Biomedical

Enginecring Dcpartmcnr, Thadomal Shahani

Engineering College for permi([ing ro do

implant ([aining and project work ar BARe.

References

1. Hill, W. and Mohapatea, S.N. (1977),'The current status of elemical impedancetechnique for monitoring of cardiac output

and limb blood flow.',IEE Medical

Elecrronics Monograph,5, Perer PeregrinusLtd.,UK., pp. 58-105.

2. Jindal, G.D., Nerurkar, S.N., Pednekar,

S.A., Babu, J.P., Kelkar, MD., Deshpandc,AK. and Parulkar, G.B.(l990a), 'Diagnosisof peripheral anerial occlusive disease usingimpedance plethysmography.', J.Po,tgrad.Med. ,36, pp.147-153.

3. Jindal, G.D., Pednekar, S.A., Nerutkar,

S.N., Babu, J.P., Masand, K.L., Gupta,DK, Deshmukh, H.L., and Parulkar, G.B.

(1990b), 'Diagnosis of venous disordersusing impedance plethysmography.'JPostgrad.Med.,36, pp.158-163.

4. Kubicek, W.G, Karnegis, J.N., Pa([erson,R.P., Wirsor, D.A., and Matison, RH.

(1966), 'development and evaluation of animpedance cardiac output system.', Aero,p.Md., 37, pp.1208-1212.

5. Mohapatra, S.N. (1981), 'Non-invasivecardoi-vascular monitoring by elemicalimpedance technique', Pitman Medicals,London, pp. 189-206.

6. Nyober, J. (1960), 'Regional pulse volumeand perfusion flow measurement" Elecrricalimpedance plethysmography', Arch Int.Md, 105, pp. 264-276.

7. ParulkaL G.B., Padm"hree, Bapar, D., Ege,R.V., Shagiani, K.e. and Jindal, G.D.(1981), 'A new dewical impedanceplcthysmograph, Obscrvarions in peripheralarterial occlusive discase.', J. Postgrad. Medpp.66-72.

This paper was awarded como/atio/l (UG) prize ill the Smde/lt Paper competitio/l i;;ri/lg-th,Symposium OIl Biomedical E/lgi/leerblg a/ld Nuclear Medici/le (SBME-NM 2000)

hzi,f#at BAJRC duri/lg la/wary 27-212000.

I '" I---

Ab,ut the auth", .

Me TS. Ananthakeuhnan;' a Pv" Geaduate in Ph}'i"frvm Cali,", Univmity (1975). He i, fivm

the 19th Batch 'IBARC TeainingSth,,1 and h", been w"king in EI""vni" Divi,ivn, BARc,frvm

197~ F" the I"'t fiw yea", he h", been in"lved in wftwa" develvpment fie vaeivu, imteumen" fie

Nueleae Amlaat"" Reac"', Ph}'i" Expaimen", UI"awnic Imaging and Medical Imteum,"" dad

in the teview 'I C'mputa bated '}'tem, fie nuckae p,wa pldn".

De G.D. Jindal J,ind BARC Teaining Sth,,1 in 1973 afta paHing Ms,. in Ph}'i" frvm Punjab

Univmity, Chandigaeh. He Jvined Bi,.Medicallntteumentati,n Geeup vI Eketeeni" Div;'ivn in

1974 and tinte then h", been w"king in the field vI Bi,.Medical Engineering. He ha, made

n'tew"thy "nteibuti,n in the ficld vI Elettmmyvpaphy, UI""'vnvpaphy, Gamma Ray Scintipaphy

and 1mpedante Plethy'm'paphy. He ,btained Ph.D. in Applied Biv"'!:! frvm Univ",ity vI Mumbai

in 1989 fie hit w"k ,n Vet'" Impedante Caedivpaphy. At pm'"t, he i, kading a team vlttienti",

weeking in the field vI Bivmedical Enginming at Eketeeni" Div;'ivn a~d w"king vn Vd'iability

Anal}'i', Hvltee M,nitveing, Tvp'paphit, Mapping tIthe s,ain and EI,,"ical Impedante Tvmvpaphy.

. "..." .

J 111I--