' • ( / ' -

Atomic of Canada LimJIect

PROGRESS

CHEMISTRY M B

October 1 to

OSM1S1ON

3Î, 1989

.P'R-CMa-11

CKalk• - . ^ • •

' ". ' V

m<0AÈCU352Î

PR-CM a- 1 1

ATOMIC ENF.RGY OF CANADA LIMITED

Chalk River Nuclear Laboratories

PROGRESS REPORT

O c t o b e r 1, 1 «•-><-» - D e t t m l j i M - M ,

( . : I I I - : M I S T R v A N D M A I ' K H I A I . S D I V I S I O N

( " b a l k H i v r r , ( ) n t a r ., •.

T h e 1 r e s u l t s a n d i o i u l u s i n n s t^ i \- » • : i h e r ' 1 a r r t i n t •. l a :- s U U ' : ! ' T

r e s t r i c t f d i n a n y H a y , h o w e v e r , s u m r n l t h f i : i l ' > r m a l U M I I S n f a

p r e l i m i n a r y n a t u r e . R e a d e r s i n t e r e s t e d i n U S H I ^ t h « • i n t u r n i d i i i m n i t h

o w n r e s e a r c h a r e i n v i t e d t o i d t i s u l l H i t h t h e i o n t r i h u t o r s t o r f u r t h e r

d e t a i l s . C o p i e s o f t h e A K ( U . p a p e r s a n d r e p o r t s r e f e r r e d t o m t h i s

r e p o r t m a y b o o b t a i n e d b y w r i t i n g l < - t h e S i i e n t i f w D m u n i i ' i i i D i s t r i l m i

O f f i c e , C h a l k R i v e r N u c l e a r I , a l > o r a t o r t e ^ .

\ !

(ii) PR-CMa-11

PROGRESS REPORT

October 1, 1969 - December 31, 1969

CHEMISTRY AND MATERIALS DIVISION

Acting Research Director

Assistant Director

Secretary

Dr. L. G. Elliott

Dr. T.A. Eastwood

Mrs. A. E. Goodale

Contents

TOPICAL REVIEW

1. SOLID STATE SCIENCE BRANCH

2. GENERAL CHEMISTRY BRANCH

3. PHYSICAL CHEMISTRY BRANCH

4. MATERIALS SCIENCE BRANCH

5. McMASTER UNIVERSITY

6. UNIVERSITY OF OTTAWA

7. UNIVERSITY OF WESTERN ONTARIO

T .

F .

w.

D.

B .

H.

C.

A. Eastwood

Brown

H. Stevens

R. Smith

Cox

G. Thode

, Rov

Page

(iii)

1

Z5

55

69

94

96

97

(iii) F R - C M a - l l

CHEMISTRY AND MATERIALS DIVISION

TOPICAL REVIEW

by

T. A. Eas twood

Ana ly t i c a l Science at_CRNL

Almos t al l e x p e r i m e n t a l s c i e n t i s t s and e n g i n e e r s at CRNL need

to know, at one s tage o r ano the r , m o r e about the m a t e r i a l s with which they

a r e w o r k i n g than they can obtain by me thods immedia te ly avai lable to them.

Under t he se c i r c u m s t a n c e s they usual ly ca l l on m e m b e r s of the General

C h e m i s t r y Branch for d i r e c t help or a d v i c e . C o n s e q u e n t s this Branch

r e c e i v e s a l a rge n u m b e r of r e q u e s t s for both qual i ta t ive and quanti tat ive

a n a l y s e s of a wide v a r i e t y of subs t ances ranging from o r g a n i c chemica l s

to m e t a l l i c a l loys . By the na tu re of the o r ig in of the r e q u e s t s it is s e ldom

that e s t a b l i s h e d m e t h o d s can be used and some r e s e a r c h or development

m u s t u s u a l l y be done to ach ieve the d e s i r e d ends . Before sur h s teps a r e

taken the r e q u i r e m e n t s a r e thoroughly d i s c u s s e d with the o r ig ina to r of

the r e q u e s t to e s t a b l i s h exact ly what in needed as well as to a s c e r t a i n

how p r e s s i n g the need i s . The g e n e r a l approach to the p rob l em is then

s e l e c t e d so as to make the most efficient u se of our r e s o u r c e s . Very

f requen t ly the choice is one of the newer methods of a n a l y s i s , based on

phys i ca l p r i n c i p l e s , that a r c rep lac ing o lde r ''wel - c h e m i c a l " p r o c e d u r e s .

To e n s u r e ana ly t i ca l r e s u l t s c o m m e n s u r a t e with '.he advanced

n a t u r e of the p r o g r a m s or ig ina t ing the ana ly t ica l r e q u i r e m e n t s , the

a n a l y t i c a l scir-ntists have the addit ional r e spons ib i l i ty of doing basi i

r e s e a r c h in their s p e c i a l t y . In this way they move forward with advan c K

in s c i e n c e and technology and a r e thus placed in a posit ion to par t ic ipa te

ef fec t ive ly in the n u c l e a r power p r o g r a m .

Our r e s e a r c h has cent red on m a s s spec t r o m e : ry , alomii

a b s o r p t i o n s p e c t r o m o t r y , nuc lea r t echn iques and the au tomat ion ol these

m e t h o d s , s ince not a l l a r e a s of m o d e r n ana ly t ica l sc i ence can be covered

with the m o d e s t effort a v a i l a b l e . In the past year some of the advarues

m a d e in these fields have been used in the heavy wate r and r e a l t o r fuels

p r o g r a m s in AECL and e l s e w h e r e in the Canadian nuc lea r indus t ry . T h e s e

a r c d e s c r i b e d in m o r e de ta i l below.

(iv) PR-CMa-11

ai Heavy Water Program

Methods for the accurate determination of the hydrogen contentof the heavy water used in reactors have received continuing attention formany years. With the increased emphasis on heavy water productionmethods, those studies have been broadened to include the determination ofihe deuterium content of natural v/aters and other potential deuteriumsources. Those methods have also found use in the hydrological studiesmade in the Biology and Health Physics Division at CRNL and mention ofthe absolute determination of the deuterium content of international naturalwater standards was made in the Topical Review for PR-CMa-5 (April-June, ll)h8, unpublished).

In addition to samples with approximately the natural abundanceof deuterium there are many samples arising from other parts of then search and development program. These samples cover a wide rangeof H-D ratios and usually demand the highest accuracy attainable. Amass spectrometer which measures the ratio of the mass (Ha) to mass 3(HD) currents when operating on a hydrogen gas feed has been found to bevery useful for such work. Hydrogen streams can be analyzed rapidly butthe analysis of other substances is more time-consuming because carefulsampling, followed by pre-treatment to form hydrogen from the substanceis required before mass analysis. Water, for example, is converted tohydrogen by reaction with hot uranium prior to analysis. To increase theefficiency of operation of the mass spectrometer for water analysis anautomated system for sampling has been devised. The key component inthis system is a glass capillary probe so designed that each water sampleis taken in a way that allows lor vapourisation, conversion to hydrogenand delivery of the hydrogen to the mass spectrometer at ihc proper flowrate, while at the same maintaining the H-D ratio characteristic of the bulksample. This capillary probe is a new device for taking water samplesfor H- D analysis and is being patented. A sample changer and recordercomplete the automatic system for routine analysis.

A production heavy water plant needs, for control, H-D ratiomeasurements on process streams. The precision demanded is lowerthan that needed for the research programs, but on the other hand, theequipment should be more rugged and simpler if possible. In cooperationwith the Canadian General Electric Co. , infra-red methods have beendeveloped and recently a time-of-flight mass spectrometer, automated ir.the manner described above, has been assessed for plant control use. Itis very probable that both the infra-red and mass spectrometer methodswill be used at the Port Hawkesbury and Bruce heavy water plants.

(v) PR-CM a-11

In addition to those- methods for isotopic ratio measurement H ,

applied r e s e a r c h programs on heavy water have brought with them

requi rements for the analysis of new mate r i a l s and important among these-

a re ammonia, amines and a var ie ty of other nitrogen compounds. The

special fea tures required in most of these analvs is have been worked out

from the es tabl ished chemist ry of the compounds involved,

b) Fuel Development P r o g r a m

The fuel development program makes major demands on

analytical sc ience . Each new fuel or sheathing mater ia l ra ises new

requi rements for analysis . Solutions are usual ly found quickly by calling

on past exper ience but one that has received special attention in the past

year is related to the measuremen t and control of hydrogen -containing

chemicals in UOS fuel. Decomposition of hydrogenous mater ia l s during

the i r radia t ion of the fuel yields hydrogen which may then attack the

zirconium alloy fuel sheath and cause hydriding. Excessive hydriding

leads to sheath fa i lure . The investigation, made in cooperation with the

Canadian Westinghouse Co. , Canadian General E lec t r ic Co. , and the

Fuel Engineering Branch, involved the determinat ion of hydrogen in

various chemica l forms •••- molecular hydrogen, water and hydrocarbons -«•

in experimental and production fuel e lements . Methods of extract ion were

as ses sed and methods of ana lys i s , using gas chromatography and m a s s

spec t romet ry were establ ished.

A final example of the application of advanced methods to

analytical p rob lems concerns a nuclear method. The advantages of

neutron act ivat ion analysis a re widely appreciated by now. Less w.dely

used are methods involving nuclear reactions induced by charged par t ic les .

The application of Rutherford scat ter ing of helium ions to the analysis of

surface contamination was d iscussed in the Topical Review for PR-CMa-7

(October - December , 1968, unpublished). F u r t h e r research on charged

par t ic le r eac t ions for a variety of analytical purposes suggested an

application to the determinat ion of fluorine on fuel element sheaths-.

This developed into an interest ing study which has just recently been

completed.

Most manufacturers of zirconium fuel sheaths treat their

product with a cleaning solution containing fluorine compounds, which is

followed by water washing in finishing opera t ions . The lluorinc contamina-

tion remaining on the surface after washing is low but fluorine is a

cor ros ive e lement and an its concent rat ion on finishi-d sheathing is a

mat te r of concern to fuel eng inee r s , A nuclear im-thod lor nu-asti r ing

(vi) PR-CMa-11

the fluorine, based on the l 9F(p, ay)1 *O reaction induced by low energyprotons from the 2 MeV Van de Graaff Accelerator, yas studied. Theconcentration was estaimated by comparing the number of v-rays emittedfrom the test samples with the number emitted from standards.

It was found that Zircaloy tubing from the manufacturer had auniform low concentration of fluorine over the interior surface. Afterthe welding and brazing operations the fluorine levels were much lower inthe heated regions. Depth profiles for the fluorine in the heated zoneswere investigated by varying the proton energy above the sharp resonancein the reaction cross-section at 1,38 MeV. These showed no fluorinebelow the superficial deposit and suggest that the surface fluorine evaporatesduring heating and does not diffuse into the body of the metal. It is there-fore unlikely that serious fluorine concentrations are established bydiffusion during fuel element fabrication.

These have been examples of the application of advancedtechniques, not always developed for the needs of the moment, to diverserequirements. The experience gained from them and other similarinvestigations shows that it is only by pursuing a vigorous research anddevelopment, program in analytical science that expertise is generated todeal with the requirements arising from Canada's nuclear program.

1 - PR-CMa-J]

1. REPORT OF SOLID STATE SCIENCE BRANCH

by

F. Brown

Page

1.1 STAFF i

1.2 ION PENETRATION 41.2.1 Characteristic X-Ray Generation by 4

Channeled ions1.2.2 Thin Film and Alkali Halide Channeling 41.2.3 2 MeV Van de Graaff Operation 4

1.3 ELECTRON MICROSCOPY 51.3.1 Observation of Lattice Images in Irradiated r)

and Deformed Metals1.3.2 Electron Displacement Damage in Cobalt in 5

a High Voltage Microscope1.3.3 Dislocations in Germanium b1.3..4 Multi-Beam Lattice Images 71.3.5 Lattice Image Contrast 7

1.4 RADIATION DAMAGE AND DEFORMATION 71.4.1 Lattice Disorder in Ion-Implanted Silicon 71.4.2 Electrical Studies of Irradiated p-type *

Silicon1=4.3 Infrared Studies of Neutron Irradiated 9

Silicon1.4.4 infrared Absorption Studies of Electron 10

Irradiated Gallium Arsenide1.4.5 Low Temperature Recovery of Deformed Metals 11

1.5 RADIOACTIVATION ANALYSIS 11

1.5 .1 Surface Analysis by Nuclear React ions- 11Flour ine on Fuel Sheaths and S t a i n l e s s Steel

1.5.2 Neutron Activation Analysis of Lead-Bismuth 12Alloy

1.5.3 Neutron Activation Analysis of Meteorites 13

- 2 - PR-CMa-11

1.6 NUCLEAR CHEMISTRY I 3

1.6.1 Heavy Ion R e a c t i o n s 131.6.2 Fast Neutron Cross Sections 141.6.3 Thermal Neutron Capture Cross Sections 161.6.4 Mass Separator 161.6.5 Lifetime Measurements in 3 Cl 181.6.6 Lifetime Measurements in 4 3Sc 181.6.7 The (p,d) and (p , t ) Reaction in v s ' 7 4 G e 191.6.8 Two Body Fract ional Parentage Coeff icients 19

in the Nilsson Model

1.7 COMPUTATIONS 191.7.1 The Surface Ejection Problem in Sputtering 191.7.2 A Preliminary Study of DeChanneling Processes 191.7.3 Free Radical Losses in Radiolysis by T*7::ll 19

Diffusion and Recombination1.7.4 Concentration of Heavy Water by Distillation 20

of Natural Water in the Region of theCritical Point

1.8 SUPERCONDUCTIVITY 211.8.1 High Temperature Superconductors 21

1.9 REPORTS, PUBLICATIONS AND LECTURES 211.9.1 Reports 2 11.9.2 Publications 2 11 9.3 Lectures and Conferences 22

- 3 -PR-CMa-1

SOLID STATE SCIENCE BRANCH

1.1 STAFF

G.C.L.J.J.A.

Branch Head

Secretary-

BailCheng1

Davies3

M. Hollis3

L.M.D.P.W.D.D.A.I.V.J.R.D.C.M.L.K.V.

HoweJacksonMackintoshMarsdenMitchellParsonsSantrySwansonVa idyanathan"

J.L. Whitton

F. Brown

Mrs. J. McCorry

G.K. Bellavance (Tg)C.W.K. Hoe Ike (P.t)D. Lantexgne (Tq )J. Lori (Tg)H.H. Plattner (Rt)A.F. Quenneville !Tg)M.H, Rainville (Rt)G.A. Sims (Rt)C. Sitter (Tg)D.A.S. Walker (Tg)R.D. Werner (Tg)O.M. Westcott (Rt)

Stores, Services

D. Dixon (Rt)B. McGilvray (Rt)H.A. Timmins6 (Rt)

K.W. Dunlop (LSS)M.D. Frivalt (LA)L. Graveline (LA)W.M. Hartwick (LAIW.J. Sullivan (LA1

1 Resigned December 15, 1969On leave of absence: University of Aarhus , Denmark

3 NRC Postdoctoral Fellow4 Graduate student attached from University of Waterloo5 Returned from Educational Leave November 24th, 1969.8 Resigned December 15, 1969.

- 4 - PR-CMa-11

1.2 ION PENETRATION

1 2.1 Characteristic X-Ray Generation by Channeled IonsL M. Howe and I.V. Mitchell

A continuous flow, argon filled, proportional counterand a Si(Li) X-ray spectrometer have been adopted forthese experiments. Together they give access to the X-rayspectrum from about 1 to 100 keV. At present they haveresolutions (FWHM), respectively, of 1.3 keV at 6,4 keV and1.0 keV at 14.4 keV.

Preliminary experiments show that X-ray generationby proton or a-particle bombardment can be used toinvestigate the lattice location of copper atoms inzirconium single crystals (Cu presumed to be interstitial).Further work is in progress.

1.2.2 Thin Film and Alkali Halide ChannelingM. Hollis

These programs have been outlined in PR-CMa-10,Section 1.2.3. The design of an ultra high vacuum (UHV)scattering chamber and beam line has been completed and atwo circle UHV goniometer is in the final stages of design.The construction of a detector translation stage for thetransmission channeling experiments is almost completed.This will allow the detector to be moved, inside thescattering chamber, to any position in a 4-inch square withan accuracy of ± 0.003".

The experiments on channeling of helium ions in heatedalkali halide crystals have been limited to an uppertemperature of 200°C because the heat from the targetassembly increases the noise in the detector and thus spoilsthe resolution. Improved heat shielding is being installed.

1.2.3 2 MeV Van de Graaff OperationG.A. Sims

Some technical problems have been the cause of the down-time during the last three months. Two overload relays wereinstalled in the high voltage terminal. Repairs had to bemade to the belt charge power supply and a faulty transformer

5 " PR-CMa-li

was replaced in the vacuuir. control cabinet. However, noneof the failures were of a serious nature.

The operating schedule for the past three months i.ssummarized below.-

Month Operating time Days lost due(hours ) to failures

September 128 3October 152 4November 117 3£

1,3 ELECTRON MICROSCOPY

1.3.1 Observation of Lattice Images in Irradiated and DeformedMetalsL.M. Howfe and M. Rainville

During the last three months modifications to thelaboratory were completed, the Siemens Elmiskop 1 electronmicroscope was transferred to a new position and the newSiemens Elmiskop 101 electron microscope was installed.Several trial runs aimed at obtaining lattice images havebeen performed to date and these indicate that the newfeatures on the Elmiskop 101, such as the electro-magneticstigmators and the electro-magnetic deflection system, workextremely well. Using the n -w electro;, microscope somevery good photographs have been obtained of lattice imagesof (111) planes in aluminum (d = 2.34 À» in the vicinityof isolated end-on dislocations. One attempt at obtainingsimilar data in copper yielded lattice images of (111) planes(d = 2.09 Â) which were visible on the negatives but thesewere not suitable fcr subsequent enlargement. This latterexperiment will now be repeated witn improved conditions.A comparison of dislocation widths in aluminum and copperis of interest since these two metals are believed to haveappreciably different stacking fault energies. experimentPare also planned on irradiated copper and aluminum crystalsas previously discussed (see FR-CMa-10 Section 1.3.11.

1.3.2 Electron Displacement Damage in Cobalt in a High VoltageElectron MicroscopeL,M. Howe

Experiments were previously performed on the high

- 6 - PR-CMa-11

voltage electron microscope at Cambridge in which thedisplacement threshold energy was determined by graduallyincreasing the voltage in the electron microscope untilvisible radiation damage in the form of small dislocationloops was obtained (see PR-CMa-8 Section 3.4.3). A detailedanalysis of the experimental data has now been performedregarding the behaviour of the dislocation loops during theirradiation. It was found that the density of loops reacheda saturation value of ~ 1015 cm & within the first fewminutes of bombardment. This is consistent v-'ith a simplemodel m which migrating interstitial atoms are either (a)annihilated by comb ining with vacancies and by going tovarious sinks, or (b ) , initially form a stable di-interstitialnucleus which subsequently grows to form a dislocation loop.This model also predicts that the area of the loop shouldincrease as c3'3 where t is the irradiation time. It was foundthat the experimental data were consistent with a t' dependence.

J.3.3 Dislocations in GermaniumJ.R. Parsons, M. Rainville and C.W.K. Hoelke

The work on 2-beain crystal lattice images obtainedfrom GP [1] zones in Al-4% Cu and from neutron irradiatedgermanium (PR-CMa-10, Section 1.3.2) has been extended, inparticular by a further analysis of the images obtained fordefects in germanium. To determine more exactly the characterof thi.se dislocations we have used the two images shown inthe Topical Review of PR-CMa-10 ar.d wp have calculated trioexpected number, N, of extra planes terminating m the image.This can be expressed by the equation

N = hu + kv -t- lw (1)

where (hkl)- are the indices of the resolved planes and r uvw1

the dislocation's Burgers vectors. The resolved plane? are(11.1) and the Burgers vectors are of the type 1/2 <1JJ>.Experimentally we observe that N = 1 in both cases and fromequation (1), together with the observed displacements of theimaged lattice planes, we conclude that the dislocation viewedend on (fig. 1, page VI, PR-CMa-10) was a 60° dislocationwhile the inclined dislocation (fig. 2, same reference) was apure screw dislocation. These results have been included ina paper submitted for publication in Phil. Mag.

PR-CMa-Ll

1.3.4 Multi-Beam lattice ImagesJ.R. Parsons and CW.K. Hoelke

The new Elmiskop 101 has many features which, fromour experience with the Elmiskop 1, will greatly assistin obtaining our aim of atomic resolution. Initiallywe are using polycrystalline gold specimens and willwork towards using axial illumination four beam imagesto resolve the (002), (022), (052) and (020) planes. Sofar we have tested the machine using our earlier techniqueof tilted illumination two beam images. Very good qualityimages have been obtained showing resolution of the (200)planes (2.04 Â). Axial illumination runs are now inprogress using objective lens defocus to compensate forspherical aberration. Charged phase plates, presently beingprepared, will be tested on the Elmiskop 1 and, if successful,will be used on the Elmiskop .101 to obtain in-focus axialillumination images.

1-3.5 lattice Image ContrastJ,R. Parsons, C H , Hoelke and M. Rainville

To nullify the undesirable effects of sphericalaberration a series of photographs of the area of intersstis taken with a small focal increment difference between eachphotograph. To optimize the phase contrast in the latticeimags the focal increments must effectively bracket theoptimum value. That is, the focal distance between phasecontrast maxima of the same sign is equal to 2a /\ so thatthe focal steps used must be less than a2/X. This factnecessitates a calibration of the Eimiskop 101's objectivelens current controls to determine what current changecorresponds to the desired change in focal length. Thiscalibration is being done.

1.4 RADIATION DAMAGE

1.4.1 Lattice Disorder in Icn-Implanted SiliconD.A, Marsden

It has been shown (PR-CMa~10) that when iodine ionsof up to 150 keV energy are implanted in silicon singlecrystals at room temperature the lattice disorder introducedincreases linearly with implanting energy. It is proposedto extend the implanting energy to higher values andeventually arrive at an estimate of the contribution of

8 - PR-CMa-11

electronic stopping to the slowing down of heavy ions. Theenergies required exceed the implanting energies availableon the Isotope Separator. Beams of some heavy ions atenergies up to several MeV could be made available on the15° arm of the 2 MeV Van de Graaff. However, in order toknow the dose, in ions/cma, the beam must be uniform overa reasonably large and well defined area, say 0.5 cm . Toachieve this on the Van de Graaff a beam sweeping system isrequired. A suitable system, described by Walker (D.A.S-Walker,Nucl.Inst. and Meth. J0_, 123 (1969)), has been built and isready for testing.

In determining lattice disorder,from the backscatteringyield of a 1 MeV He+ beam, the area of the damage peak isvery sensitive to the way in which the background is estimated.This background is a result of the dechanneling that theincident beam undergoes because of the disordering of thecrystal lattice(in the surface oxide and in the damaged regionitself. Bjzigh (Can.J.Phys. , 46., 653 (1967)) has shown thatthe background can be reduced and thus the sensitivity of thetechnique increased by using the double alignment technique.In this technique the analyzing beam is incident on thecrystal along a major low index direction and the detector isaligned with another major low index direction.

In order to develop this technique further we have usedcellulose nitrate film patterns of backscattered 1 MeV He+

particles to determine the required geometry of a tungsten<111> oriented crystal. A detector is then positioned behindthe film at the <110> axis. With the film removed, the beamis brought in along the <111> direction and the minimum yieldin this direction then measured on the aligned detector. Areduction of -* 300 in the yield in the doubly aligneddirection over the yield in a random direction was obtained.This reduction is to be compared with a reduction of ~ 60in the singly aligned case for 1 MeV He+ and the <111>direction in tungsten and is sufficient to show that thetechnique is promising. However the calculated estimate forthe reduction in the doubly aligned case is 'u 4000, suggestingthat further improvement is possible if the detector can bealigned more a--.:urately. An improved mechanical arrangementis being constructed.

' n " PR-CMa-11

1.4,2 Electrical Studies of Irradiated p-type SiliconL.J. Cheng and J. Lori

An isochronal annealing experiment, from 80°K to2 00°K, on two p-type silicon samples (one cut from a1000 n-cm B-doped crystal with 5 x 1017 oxygen atom/cm3

and the other cut from a 53 0 w-cm B-doped crystal with^ 10iS oxygen atoms/cm3) was performed after the sampleshad been irradiated with 3 x 1014 1.2 MeV electrons/cm3

at 15°K. The sharp 1"5°K annealing stage appeared in bothsamples. An analysis of the present data and the data reportedin PR-CMa-10 indicates that this stage, observed in highresistivity samples (> 500 fi-cm) only, cannot be attributedto the migration of neutral vacancy. Also the recovery stagein the temperature range from 160 - 200°K observed in p-typesilicon is very complicated and depends on the concentrationof the electrically active dopant in the crystal. G.D. Watkins(private communication) has some experimental evidence fromEPR studies that the production rate of the isolated vacancyin B-doped silicon decreases with decreasing dopant concentra-tion in the range about ~ 101B B atom/cma. All these factsstrongly indicate that the isolated vacancy as observed byWatkins in low resistivity silicon (~ 1 Q-cm) (J.Phys.Soc.(Japan) _18_, Suppl.II, 25(1963)) is not one of dominant defectscaused by Co-60 gamma rays or 1.2 MeV electrons in highresistivity p-type silicon.

1,4=3 Infrared Studies of Neutron irradiated SiliconL.J.Cheng and J. Lori

The production rates of the 1.8 M- absorption band andthe near edge absorption in Si by fission neutrons in thetemperature range from 145 to 300°C were studied. The resultsindicate that the annealing behaviour of the divacancy and thedefects causing the near edge absorptio-n during irradiationin this temperature range is the same as that after anirradiation at 50°C. This result differs from the result ofPicraux et al. in a study of the temperature dependence oflattice disorder caused in Si by 40 keV Sb ions (Applied PhysicsLetters, 1±, 17 (1969) indicating some difference betweentwo kinds of damage. This may be due to differences in doserates, in fluences, in the spacial distribution of defects,and in relative concentrations of different kinds of defects.The difference in dose rates and fluences should be emphasized

- 10 - PR-CMa-11

strongly, because the production rate and the totalnumber of damage regions in our case are, respectively,about 3 and 4 orders of magnitude smaller than those inPicraux's case.

1.4.4 Infrared Absorption Studies in Electron Irradiated GalliumArsenideK.V. Vaidyanathan

Several samples of GaAs were irradiated with 1.5 MeVelectrons at room temperature. The samples received afairly large dose (approximately 10i(' electrons/cma ) .Infrared studies were carried out on the samples both atroom temperature and at liquid nitrogen temperature. Theresults are as follows.

The room temperature spectrum failed to show anystructure. The fundamental absorption edge almostdisappeared. It was found that transmission increasedmonotonically with wavelength. These results seem to agreevery well with those obtained by Aukerman et al. (Appl.Phys.34. 3590, (1963)) .

The spectrum at liquid nitrogen temperature howevershowed a rathei. broad but well defined peak at 1.25 p..The peak was found to grow in intensity with e^ctron dose.After establishing that the peak was really due to damagecreated, annealing studies on these samples were carriedout.

The isochronal annealing studies were carried out invacuum and the annealing period was 30 minutes at intervalsof 20°C. Preliminary results seem to indicate that thereis no recovery until 140°C. The defects completely annealout between 3 00° and 35O°C. There appeared to be twoannealing stages, one at about 160°C and the other between300°C and 350°C. These results seem to disagree with thoseof Aukerman whose results indicate that the recovery iscomplete at 220°C.

More isochronal anneais are being carried out. It isalso planned to study the isothermal annealing behaviourof these defects with an aim of obtaining an activationenergy for the process.

" ] ] " PR-CMa-11

1.4.5 Low Temperature Recovery of Deformed MetalsM.L. Swanson and A.F. Quenneville

Further experiments on the low temperature recoveryof deformed Cd and Zr have been performed, in order toverify and extend previous results. A Cd sample, whichhad been annealed at 200 GC to obtain a large grain size,was deformed at 4°K and its isochronal recovery up to75°K was measured by residual electrical resistivitymeasurements. The sample was then deformed again andthe second isochronal recovery spectrum was measured.As in previous samples (PR-CM-49), the second recoveryspectrum differed considerably from the first. Below10°K, the second recovery was less than the first, butfrom 10-20°K and from 25 - 30°K, it was much greater.These results show clearly that the defect distributionis greatly affected by the previous history of the sample.A Materials Research Corporation Zr sample (containing ~0.07 at.% 0) was deformed at 4°K and annealed up to 280°C.The total recovery was 125%; this result suggests that theredistribution of impurity atoms (likely either 0 or H ) ,is aided by point defects produced by the deformation. Adetailed examination of the higher temperature recoverycould yield the activation energy for vacancy migration inZr.

1.5 RADIOACTIVATION ANALYSIS

1.. 5 .1 Surface Analysis by Nuclear Reactions-Fluorine on FuelSheaths and Stainless Steel

W.D. Mackintosh

Another way has been found to prepare comparativestandards for this analysis. Suitable metal specimensare anodically oxidized in NH4F solutions containing aknown proportion of F-18. The total F deposited in theoxide layer can thus be determined by conventional countingtechniques. The method has two advantages over the vapourdeposition method previously described. (a'i The depositis more uniform from one point to another, (b) It iseasier to prepare a series of standards with a wider rangein concentration. Plots of Y yields vs concentration werelinear over the range of 0.5 to 3 vig/cm3 with if. a precisionof 5%.

" 1 2 • PR-CMa-11

It has been found possible to determine the fluorinecontamination in the area surrounding a defect whichdeveloped in a fuel sheath at 8000 MWd/tonne. Theactivities due to the irradiation in the reactor emittedY's of much lower energy than those for the 19F(p,(XY)lS0reaction used for the analysis- Some loss of accuracywas experienced due to the higher dead time loss of thecounting system.. A surface deposit of only 0.1 |a,g/cmwas found. It is unlikely that fluorine contaminationcontributed to the production of this defect.

A corroded spot on a stainless steel bolt which hadfailed in service on a loop coolant-water pump showed asurface deposit of 3 M.g/cm3 , This is considered to beevidence that a fluorinated hydrocarbon lubricant hadbeen used during assembly of the pump.

1.5.2 Neutron Activation Analysis of Lead-Bismuth AlloysW.D. Mackintosh and H.H, Plattner

The following analysis were performed on Pb-Bialloys and components from the FC-2 loop for the EngineeringResearch Branch (PR-CMa-6)

Pb-Mg mixture with Zr added

6 samples for Zr., all < -1 ppm.

Nb deposit on wall of pipe from FC-2 loop

4 samples for Nb, 28-44 p,g/cms

Solidified contents of FC-2 Pump No.2

Sr, 992 ppm

Nb, 80 ppm

UaSi Experiment

Top of trepanned slug for U, 1-54%.

1 1/2" from top surface for U, 122 ppm.

- 13 - PR-CMa-11

1.5.3 Neutron Activation Analysis of MeteoritesW.D. Mackintosh and H«H. Plattner

A great deal of the knowledge of the cosmic abundancesof the elements is derived from neutron activation analysisof meteorites. The method has two advantages (a) sensi-tivity (b) the ability to virtually guarantee freedom fromterrestial contamination by scraping off the outer surfaceafter irradiation. The exceptionally high neutron fluxesavailable in NRU and NRX make it attractive to do someof this work at CRNL. Two samples have been obtainedthrough the courtesy of Dr. P. Millman of NRC, One isBenton, a Canadian find, the other Allende which was seento fall in Mexico in February, 1968.

A series of preliminary experiments has been initiatedusing common rocks as samples to investigate the possibili-ties in both direct analysis by irradiation followed byY ray spectroscopy and in irradiation followed by radio-chemical separations into groups of elements before counting

A piece of granite rock was irradiated for 90 hrs andallowed to decay for 1 week before counting to reduce thehigh level of activity due to 15-h 2"Na. The y-spectrashowed that Ta, Se, Fe, Hf, Eu, Zr, Co, and Th are presentin sufficient quantity to be determined directly using ahigh resolution Li-Ge detector.

Separation methods are being tried for Au, Ag, Pd, Ir,and Os.

A method for determining which minerals contain U hasalso been tried. A piece of granite was cut and ground downto a thin transparent wafer. It was irradiated for a fewminutes in contact with a cellulose nitrate film. Thiswas subsequently etched to reveal the fission producttracks. The tracks showed areas of higher U concentrationand these areas could be identified with particular crystalswithin the granite matrix.

1.6 NUCLEAR CHEMISTRY1.6.1 Heavy Ion Reactions

D.C. Santry and R.D. Werner

Processing of data from studies of the 0 + Crreaction (see PR-CMa-9, 1.4.1) is nearing completion.

- 14 - PR-CMa-11

Gamma spectra obtained from on-line measurements andfrom decay of reaction, products resulting from de-excitation of the compound nucleus 5 eGe, have beenprocessed to obtain photopeak energies and areas. Thetargets bombarded consisted of thin layers of evaporated53Cr(50 to 250 ^g/cma) on thick backings of Au or W(960 and 690 mg/cma). Since the l D0 beam was stoppedin the backing material, on-line measurements of thecharacteristic gamma rays due to coulomb excitationof Au or W were used to determine precisely the integrated1'0 flux for a bombardment. Similar analysis of coulombexcitation of B3Cr was used to determine the thicknessof Cr actually bombarded for the activation measurements.This additional information on coulomb excitation ofCr, W and Au in the energy region 35 to 57 MeV is alsobeing processed.

One interesting feature which is now evident is thatalthough the coulomb barrier for the 1 60 + BaCr reactionis v> 37 MeV, bombardments carried out at 35 MeV haveoroduced 9.5 hour s 6Ga, one of the products of de-excitationof S 9Ge.

1.6.2 Fast Neutron Cross SectionsD.C. Santry and J.P. Butler

In processing data from measurements of the 6'!Zn!n,p)-'Cu reaction, it was possible te extract crosssection values for two associated reactions which occurwhen natural zinc is irradiated with fast neutrons.

•j8Zn(n,a)r' BNi Q = 0.83 MeV"'0Zn(n,2n)e9mZn Q = - 9.29 MeV

The 2 .. 56 hour c5Ni act ivi ty was measured by beta countingwhile the 13.9 hour = 9mZn act ivi ty was aetermined by gammaray spectrometry. Preliminary excitation curves are shownin Figure 1.6.2.1. Upon completion of analysis, crosssection values for these reactions will be included with thepublication of the s 4 Zn (n ,p)c''Cu data.

Samples of sulphur, magnesium, aluminum and zinc wereirradiated in the E3 transformer rod position of the NRXreactor. A description of the irradiation faci l i ty wasgiven by Boyd et a l . AECL 2203, January, 1965. Effective

- 15 -PR-CMa-]1

cross section values determined for the present K3reactor spectrum are l i s t ed in Table 1.6.2.1 along withvalues measured by BoJdeman (J .Nuc .Energy, JJ3_, 417 (19<">4))also, values obtained by integrating our excitation curvesover a f iss ion neutron spectrum are given. Apparentlythe transformer rod no longer produces a pure fissionspectrum. i t was hoped tha t these measurements woulds e t t l e the discrepancy between the value measured byBoldeman for the S4Zn(n,p) reaction and our calculatedvalue (see PR-CMa-7, 1.4.1).

Table 1.6.2.1Effective Cross Section Values for a Reactor Spectrum

Reaction Cross Section (mbj

Measured in E3 Measured- Calculated-Boldeman Santry & Butler

3 2 S ( n ,a 4Mg(nS 7 A l ( ns 4 Z n ( n

p ) 3 a P, p ) a 4 N a, a ) 2 4 N a, p ) 6 4 C u

6 3 . 61.140 . 5 7 0

3 3 . 9 9

10

6 0. 3 1. 6 027

6310

44

.6

. 3 8

. 6 3

.2

normalized to calculated value

Excitation Curve for 7 °Zn (n ,2n )r' 9mZn and 6 BZn ( n ,g '"' 6NiReactions.

10 II I I I I 14 IS ••

•tUT«OH INIItfV IHlVI

F i q u r e 1 . 6 . 2 . 1

- 16 - pR-CMa-11

1.6,3 Thermal Neutron Capture Cross Sections

D.C. Santry and R.D. Werner

The mass separator was used to implant known amounts(50.000 M coulombs, 3.1 x 10 1" ions) of lalSb and l 2 3Sbinto Al foils which were then irradiated along with Au-Al

' flux monitors in a thermal neutron position in the NRX

reactor. The data from radioactivity measurements of theirradiated material have been processed to obtain capturecross section values for 1 3 1Sb and l 2 3Sb. Repeatedmeasurements, however gave inconsistent results which wereabout a factor of 5 to 6 below cross section values givenin Neutron Cross Sections (BNL 325). Variations in theratio of l :? ' Sb to I a 3Sb collected suggested that Sb wasbeing lost from the foils during ion implantation.Confirmation of the loss was obtained by varying theamount of 1 3 1Sb implanted, as measured with a Faraday cup,and using activation analysis to determine the relativeamount of Sb collected. The results are given inTable 1.6.3.1.

Table 1.6.3.1Ion Implanted 40 KV 1 a'Sb into Al Foils

Faraday cup measurements\x coulombs ions

Activity measurementsrelative activity relative

activity/coulomb

5,01010,00525.01050,042

3613

.1 X

.2 x,5 5x.1 X

101'"10l"io:7

1017

57.2

74.46144.3

145.1

11752

.42

.44

.77

.89

1.6.4

The loss of Sb by sputtering renders this technique forsample preparation unsatisfactory for cross sectiondeterminations. Decreasing the implanted dose to a valuewhere sputtering losses are negligible, yields too littlematerial for accurate activation measurements. However,it may be that the technique can ba used for other systemsie. other implanted species and/or other target materials.

Mass SeparatorD.C. Santry

Thin Target Implantation

A request from the Nuclear Phys-ics Branch to produce

- 17 - Pk-CMa-:

thin targets of deuterium for nuclear read ion studieswith the Tandem accelerator, has initiated a s_udy of Unnfoil bombardments with the mass separator. The choice oftarget material was nickel since it can be obtained asvery thin foils with good tensile strength (Marion andYoung. Nuclear Reaction Analysis. North Holland Pub.Co.1968 p.116). Based on a calculated projected range for40 KV D a

+ ions in nickel as ~ 264 hg/cma, foils of thickness

445 M-g/cm2 (5000 A) were used. A 50 p> amp beam of D?+ wasswept over a target area of 0.25 cms . All foils broke withlesc than 101 ions implanted. The implants were repeatedusing 890 ng/cm3 nickel foils; they also broke. Although itmay be possible to implant deuterium successfully atgreatly reduced beam currents, the bombardment timerequired to introduce suitable quantities of deuteriumwould be prohibitively long (50 ^ amp for two hoursimplants 7 p,g of deuterium). Attempts will be made toproduce the targets by adsorption of deuterium into anevaporated layer of titanium on the nickel foils.

The results of these implantations indicate that icn.implantation studies on tho mechanism of sputtering usingtransmission measurements will be difficult. The thin foilsrequired for such measurements will not withstand the largebeam currents necessary to observe sputtering.

Retention of Ion Implanted Sb.

The loss of Sb from Al foils during ion implantation(see section 1.6.3 above) was examined further to see ifit was possible to correct for or overcome this difficulty.Measurements were performed in which collective foils wereplaced in a Faraday cup foi bombardment. ThLS provideda precise measurement of a swept beam which was depositedevenly over a 1 cm x 1 cm area. A prebombardment withi22Sb introduced radioactivity into foils in tracerquantities. The foils were removed and the amount Dfactivity was determined by gamma counting. The foils werereplaced in the Faraday cup, carefully aligned andbombarded with a swept beam of stable *s"Sb over thepreviously implanted area. A remeasure of the gammaactivity after the bombardment gave values for retentionof the radioactive tracer as a function of integrated dose.The results are shown jn Table 1.6.4.1.

- 18 - PR-CMa-11

Table 1.6.4.1

40 KV-Sb implantation Into Al

Retention of tracer implant (%)

9866.141.726.1

Retention values for a given integrated dose in aluminumwere observed to depend on the so urce of the foil whichis presumably related to the oxide thickness on the surface;also the retention depends markedly on the eveness of theimplant. Retention values for other target foils were alsodetermined as shown in Table 1.6.4.2.

Table 1.6.4.2

Dose i

35

(ions/cm

10lr

x 10 l e

x 1016

10 1 7

Foil

T iS iA lWTaAu

Dose

5 x 101 6

M

II

1 1

I t

2 x 10 i6

40 KV-Sb Implantation

Retention of tracerimplant %

83.362.541.731.827.636.1

Calculated ProjectedRanqe (p,q/cma)

7 . 16 . 05 . 7

15.415.416.1

It is proposed to examine whether the loss of antimonyis due only to sputtering of the target material orwhether diffusion of the antimony to the surface plays asignificant role as was the case for inert gas implantedinto plastics (see PR-CMa-7, 1.4.2).

1-6.5 Lifetime measurements in 3 7C1G.C. Ball; F. Ingebretsen, A.J. Ferguson and B. Ader(Nuclear Physics Branch). See PR-P-83.

1.6.6 Lifetime measurements in 4 3ScG.C. Ball; J.S. Forster and F. Ingebretsen (NuclearPhysics Branch) , and C F . Monahan (Queens University) .See PR-P-84.

1PR-CMa-11

1 .6 .7 The (p,d) and (p,t) Reactions on ' " GeG.C. Ball, T.H. Hsu and B. Hird(Universlty of Ottawa).See PR-P-84

1.6.8 Two Body Fractional Parentage Coefficients in the NilssonModelR.Y. Cusson(Theoretical Physics) and G.C. Ball. SeePR-P-84.

1.7 COMPUTATIONS

1.7.1 The Surface Ejection Problem in SputteringD.P. Jackson

The computations described in the previous progressreport have been done both with a force balancing technique,which proved to be difficult and also by a potentialminimization process. Both agreed for specified cases andit now appears that some of the phenomena previously attributedto a faulty model may in fact be real. However, preciseagreement with the results given by Cotterill and Doyama forCu, Au and Al (Cotterill, R.M.J and Doyama, M. pp.1-78 in"Lattice Defects and Their Interactions" (ed. R.R. Hasiguti)- 1967)) has not yet been achieved.

1.7.2 A Preliminary Study of Dechanr.el i ng ProcessesD.P. Jackson and K.B. Winterbon(Theoretical Physics Branch)

This project is still in a very preliminary stage.Although it is intended to proceed with it, certain reassess-ments were required in view of the results presented at therecent Sussex Conference. It is not clear whether a simplediffusion model will be useful in view of the ratherextensive computer simulations of dechanneling reported.This matter is still under discussion.

1.7.3 Free Radical Losses in Radiolysis by Wall Diffusion andRecombinat ionsD.P.Jackson and D.A. Armstrong(University of Calgary)

A computar program which can be used for threegeometries (Sphere, cylinder and flat plate) and twoboundary conditions has been written and checked. It wasfound that for large values of the equation parameter

• 2 0 " PR-CMa-11

even a great many terms in the series failed to produceadequate results. Hence it is now necessary to use acombination of the series solutions for most values ofinterest and a step-by-step integration routine for highvalues. In effect the task is to mate cwo programs whichare working to produce tables that cover the completedesired range of values. This is now in hand.

1.7.4 Concentration of Heavy Water by Distillation of NaturalWater in the Region of the Critical PointD.P. Jackson

The hypothetical critical point for HDO is lower thanthat for H; 0 by 2°C and this suggests that the twowater species might be separated by a distillation processoperating between the critical points. The current stateof knowledge about water in this regime has been reviewedbut it was found that experimental information about suchthings as separation factors, fugacities and Henry's Lawconstants is lacking. Furthermore, the estimation ofthese quantities in the region near the critical points withthe accuracy needed for the present purpose appears to bebeyond contemporary theoretical understanding. It wastherefore concluded that a critical assessment of theproposal could not be made from our present state ofknowledge.

General feasibility arguments can be given whichsuggest that the method is unlikely to be economicallyattractive. The most significant of these has to do withthe flow velocities through a bubble plate column, thetype of equipment most likely to be used for the distilla-tion. The small density differences between phases in thecritical region would make it difficult to operate atreasonable column throughputs. To counterbalance this,a large separation factor, a, would be required. It isknown that a decreases with increasing temperature as thecritical region is approached. This trend would have toreverse, and by a large amount, in the critical region tomake the method economically attractive.

• 21 " PR~CMa-ll

1.8 SUPERCONDUCTIVITY

1.8.1 High Temperature SuperconductorsM.L. Swanson and A.F. Quenneville

The method of preparing dielectric-metal-dielectricsandwiches by anodization (PR-CMa-10) was shown to befeasible in the case of Ta. An electropolished bulk Tasample was anodized to an oxide thickness of 1200 Â, a7 50 A film of Ta was sputtered into the surface byNorthern Electric Co., and an anodized layer of 425 A(corresponding to removal of 17 0 Â of metal) was formedon this film. No lifting of the sputtered film wasobserved, but some breaks through to the underlying oxiduoccurred, and it was not possible to anodize further.The superconducting critical temperature of the Ta was notappreciably altered by this treatment.

In order to examine the possibility of forming small,uniformly dispersed dielectric particles in a bulk metal(PR-CMa-10) , samples of Zr + 5 at%H were quenched from"* 700°C to 4°K in a liquid He-cooled vessel. Even thisrapid quenching technique was insufficient to retain anappreciable amount of H in solution. Thus it appears thatthis method will not produce sufficiently small hydrideprecipitates in Zr-H.

«1.9 REPORTS, PUBLICATIONS AND LECTURES

1.9.1 Reports

Defects in Quenched Zirconium- M.L. Swanson, G.R. Pisrcy, G.V. Kidson and A.F. Quenneville.

AECL-3428.

Electron Equipment Manual for the Experimental Facilitiesof the 2 MeV Van de Graaff - Revision 8 August, 1969.- D.A.S. Walker, CI-234 (.'P.Cij ".IPUM ished report).

1.9.2 Publications

Temperature Dependence of Production Rate of Divacancyand Near Edge Absorption in Si by Fission Neutrons.- L.J. Cheng and J. Lori, Appl.Phys. Letters.

- 22 - PR-CMa-11

Defects in Quenched Zirconium- M.L. Swanson, G.R. Piercy, G.V. Kidson and A.F. QuennevilleJ. Nucl. Mat. (letter to the editor).

The asMg(p,t)a4Mg Reaction at 20 MeV.- R. Fournier, J. Kroon and B. Hird,G.C.Ball, F.Ingebretsenand R.W. Ollerhead. Proceedings of the Int.Conf. onProperties of Nuclear States, Montreal, 1969.

Photoconductivity in P-Type Silicon irradiated with 1.2 MeVElectrons at 15°K.

- P. Vajda and L.J. Cheng, Physical Review.

1.9.3 Lectures and Conferences

Channeling Studies of Phosphorus and Boron Implantationsin Silicon.

- I.V. Mitchell and D.A. Marsden, The ElectrochemicalSociety, Detroit, U.S.A. October 5-10, 1969.

Channeling as a Tool in Ion implantation Studies in Silicon.- I.V- Mitchell, New Directions and Techniques in Semi-conductor Research, Fall Symposium, Ontario/Quebec SectionElectrochemical Society, Northern Electric Co. Ottawa,Ontario, November 7, 1969.

Stage I Recovery of Deformed Metals.- M.L. Swanson, University of Waterloo, November 13, 1969.

In-Situ Radiation Damage Experiments in Electron Microscopes- L.M. Howe, McMaster University, Hamilton, Ont. November17, 1969.

Photoconductivity in Irradiated p-Type Si.- L.J. Cheng, Dept. of Nuclear Science, RensselaerPolytechnic Institute, Troy, U.S.A. November 20, 1969.

Theoretical Studies of Surface Ejection.- D.P. Jackson, Second Annual Canadian Seminar on Surfaces.Ottawa, Ontario, November 24-2 5. 1969.

- 23 - PR-CMa-11

Investigations of Flourine Deposits on Zircaloy Surfacesby Proton Activation.- W.D. Mackintosh, American Nuclear Society (November Meeting)San Francisco, U.S.A. November, 1969.

Charged Partical Activation Analysis.- W.D. Mackintosh, American Nuclear Society, (NovemberMeeting) San Francisco, U.S.A. November, 1969.

Recent Chalk River Experiments on Defects in Solids : Stage IRecovery of Deformed Metals.- M.L. Swanson, Max-Planck-Institut fur Metallforschung,Stuttgart, December 3, 1969.

_ 2 4 . PR-CM.a-11

- 25 -

PR-CMa-11

2. REPORT OF GENERAL CHEMISTRY•BRANCH

by

W.H. Stevens

2.1 STAFF

2.2 ANALYTICAL CHEMISTRY 282.2.1 Emission Spectrography 282.2.2 X-Ray Fluorescence Spectrometry 282.2.3 Atomic Absorption Spectrometry 292.2.4 Gas Analysis 3!2.2.5 See CRNL-160-7 312.2.6 General Analyses 322.2.7 Service Analyses 32

2.3 FUEL ANALYSIS 342.3.1 Molybdenum as a Burnup Monitor 342.3.2 Half Life of 23"U 36

2.4 RADIOACTIVITY MEASUREMENTS 362.4.1 Adsorption of Tellurium - Laboratory Studies 362.4.2 Counting Room 42

2.5 HEAVY WATER ANALYSIS 422.5.1 Natural D/H R 42

2.6 ELECTROCHEMICAL H/D SEPARATION 452.6.1 Elsctroche.nical H/D Separation 45

2.7 SPARK SOURCE MASS SPECTROMETRY 472.7.1 Trace Analyses of Lithium - Drifte< Gernanium 47

Seni-Conductors2.7.2 Determination of Impurities in p-Type Silicon 47

Detectors2.7.3 Environmental Sample Analysis 482.7.4 Lie.Mid Metal Coolant Analysis 482.7.5 Standardization and Calibration of SSM1 492.7.6 GEC/AEI 702 Mass Spectrometer 50

2.8 MASS SPECTROMETRY . 512.8.1 NRU Thoria-Urania Flux Peaking Rods 512.8.2 2200 m/s Cross Sections of Fissile Nuclides 522.8.3 Separation of Lithium Isotopes 522.8.4 Burnup Measurements 5<f

2.9 REPORTS, PAPERS AND PUBLICATIONS 542.9.1 Conference Papers 54

Branch Head

Secr3tary

ANALYTICAL CHEMISTRY

P. ',','• Ashley.:.P. Mis] anG. I'.otov

- 26 -

GENERAL CHEMISTRY BRAuCH

2 . 1 STAFF

W.H. Stevens

PR-CMa-11

'Mrs,. Jutta Spanier2Mrs. Doreen Childerhose

FUEL ANALYSIS

i.W. Durham

RADIOACTIVITY MEASUREMENTS

tt.C. Hawk ingsW.J. Edwards

HEAVY WATER .ANALYSIS

W.H. Stevens

ELECTROCHEMISTRY

W.H. Stevens>!. Hammerli

SPARK SOURCE MASS SPECTROMETRY

j^H. CrockerL.w". Wrav

A.S. DennvanP.S. HardyG.R. MatteauMrs. E.D. BellavanceT. BruceS. ElchukJ.H, MunchG.J. JarboM. Corri\-".'iu

L.P.V. CcrriveauF.C. MillerF.W. MolsonL. Junop

J. BaternanMiss D. TennantMrs. E.P. GarveyMrs. D.E. Murray

(Tg)(Tg)(Tg)(RT)(Tg)(Tg)(RT)(•V)

(LA)

(Tg)(RT)(RT)(LA)

(RT)(RT)(RT)(RT)

W.M. Thurston

W.J. Olmstead

(Tg)

(RT

MASS SPECTROMETRY

M. Lounsbury

LABORATORY SERVICES

D. Poirier (LA)

W. CherrinJ.A. Schrunjr

PR-CMa-11

(Tg)(FT)

!Mrs. Jutta Spanier terminated November 28, 19692Mrs. Doreen Childerhose transferred from Staff Development andWelfare Branch - December 1, 1969

Tg - TechnologistRT - Research TechnicianLA - Laboratory Attendant

- 28 - PR-CMa-11

2.2 ANALYTICAL CHEMISTRY

2.2.1 Emission Spectrography- G. Zotov, J. Munch

(1) Aztec Nebulizer components have been fitted into apolyethylene block provided with a hollow Ta metal electrodeholder to make a single unit, as outlined previously(PR-CMa-10). The relative position of the glass bafflewas set as recommended by an Aztec representative; thisis not necessarily at optimum location and some modificationsmay have to be made. With the present set-up the signalstrength is 90% of that obtainable with our Perkin-Elmerassembly.

Further testing of counter electrodes of differentshapes and grades of graphite (porous, soft and pyrolytic)has been done with this equipment. The tests confirm thatflat-ended electrodes of medium graphite give the strongestoutput signals and are very reproducible.

As corrosion of the spark stand components and springclips in the nebulizer was occuring from attack by theaerosol and vapour from the acid solution, a new upperelectrode assembly was constructed which can be connectedto a water pump to draw off the corrosive vapours moreefficiently.

(2) Preparation of Standards

(a) Dried Residue TypeSpectra of Pd and Pt were prepared covering the

range of 6.25 to 100 ug/ml, and of U covering the rangeof 0.4 to 8.0 ug metal on the electrodes.

(b) Carrier Distillation TypeSpectra of 32 impurities in MgO covering the

range of 0.2 to 200 ppm have been prepared.

2.2.2 ••:•'••;; -:^rescence Spectrometry- R. •.. Ashley, G~. Jar bo *~

Determination of Si in U3Si

The possibility of determining silicon in U3Si by."•ray fluorescence directly has been examined briefly.The following instrumental conditions were used:

Primary X-ray source - W targetPower settings - 50 KV

50 naAnalyzing crystal - PET

" - Prj-CMa-ll

Counter - ProportionalCounter voltage - 15 7 5 VPHA - Base line - 0.25

Window - 1.0Attenuation - 4X-ray path - vacuum

The silicon K2 line at 26 =•• 108.96° was measured and theuranium M3 line at 116.22° used as an internal standard.Counting time was 400 sec. Net counts (line-background)were about 175 c/s for 3.5% Si. Reproducibility andsensitivity were only fair, but it is felt improvementscan be made.

2.2.3 Atomic Absorption Spectrometry

- J.P*. Mislan, S. Elchuk, G.R. Matteau

(1) Non-Flame Methods of Atomic Vapour Production

I - Graphite Filament Resistance FurnaceThe evaluation of the graphite filament resistance

furnace for automated trace metal analysis is continuing.Development has been directed to the following:

(a) Oxidation Rate of Graphite Components

The most serious practical limitation of thetechnique is a short operational life of filamentcomponents. Even though filaments are relatively easyto prepare and replace, re-standardization is a timeconsuming task. Filaments are prepared fron two formsof graphite -(1) cloth (pyrolyz- :1 textile) which serves to dispersesolvent drops during deposition (pre-evaporation) and(2) low density pyrolytic graphite tape which providesheat via rer.istance heating tor the deposition step(-1200OC) and a much higher temperature (2200°C) foratomic vapour production. Disintegration of the clot'.by oxidation results in pc •• pr-' • - . : :>>r sampledeposition while erosion of the pyrolytic qraphitetape results in a termination of resistance heatinq.

In the absence of sample deposition, thefilament consistmq of two strips of pyrolytic araphitctape (30 mm x 6 mm x 0.25 mm) with the cloth (6 nn x f. nm)sandwiched between, fails after approximately 800thermal cycles at 2100°C and 10-20 cycles at 2400^0.The limit of filament life under these conditions appearsto be imposed by oxygen in the vicinity of the tape,resulting from either the purqe aas or an inefficientsweep of atmospher- oxygen by the purqe qas (900 nl/mn.)

" 30 " PR-CMa-11

It is also possible that temperatures developed withinthe layers of the pyrolytic graphite are higher th .-,the external temperature indicated by the opticalpyrometer.

When aqueous sample (0.7 mis delivered in1.4 mins) is added during the sample deposition cycle,the filament fails after approximately 40 samplingcycles. Tape life is extended to 150 cycles with 50%(by volume) CH3OH-H2O as solvent and 400 cycles with85% CH3OH-15^ H2O.

When sample aliquots are reduced by a factorof 10 (i.e. to 0.06 ml of 50% volume CH3OH-H7.O) with asmall bore quartz capillary, tape life was found toexceed 1100 sampling cycles. This observation appearsto indicate that under these conditions carbon isdeposited by pyrolysis of solvent to partially compensatefor carbon lost through oxidation, other workers haveobserved deposition of pyrolytic graphite on introductionof ethyl alcohol aerosols into hot graphite tubes.This appears to be a practical means of prolongingthe effective life of the filament without increasing thecomplexity of the entire apparatus.

(b) Range of Application

A survey is presently being made to determinethe limitations of this technique with regard toindividual metals. Problems that may be encounteredinclude loss of volatile metals (e.g. Hg) during thedeposition stage, and failure to produce atomic vapourfrom salts of refractory metals. The difficultyencountered with gadolinium analysis, thought to be dueto refractory carbide formation, has already beenmentioned (PR-CMa-10).

II - Micro-Tube Furnace

The feasibility of automated sample depositionand atomic vapour production on a sequential batch basishas already been demonstrated with a macro tube furnace(20 mm long - 0.5 mm wall thickness - 6 mm internaldiameter).

The tube furnace was developed as a potentialalterne ti-.e *:o t' r -r41.?<-nnt --•—-, with the followinganticipated advantages:

(a) greater analytical precision - lower probability^r mechanical loss of sample in the depositionstep.

- 3 1 •

P"-. CMa-ll

(b) easier alignment of analyzing light from hollowcathode lamp.

(c) longer life - the tube furnace is prepared fromhigh density graphite which has a higher resistanceto oxidation.

The tube furnace requires approximately 2.5times as much power as the filament source to attainthe same temperature, however.

(2) Determination of Potassium

A brief study of the best conditions for deter-mination of potassium by atomic absorntion has beenstarted. This arose because different results werebeing obtained on the same solution when differentdilutions were made. The followinq points are beingexamined:

(a) sensitivity in different zones of the flame,(b) comparison of results using the resonance lines

7665A and 76998.

Preliminary results indicate that the optimumposition for the beam to pass through the flame is nomore than 3 mm above the blue cone. The 7665/? resonanceline is the more sensitive but the 7699A line gives aclearer signal. Sufficient data have not yet beenobtained on statistical variation to determine if theeffects mentioned fall within the expected limits oferror or not.

2.2.4 Gas Analysis- R.W. Ashley, T. Longhurst

(1) Total Hydrogen in Graphite

Difficulties in the form of hiqh and variableblanks have been encountered in the method involvingcomplete oxiuation of hydrogen in the sample followedby gas chromatographic determination of the H.-.O formod.?n alternate method has been adooted which uses vacuumextraction at 1000°C of all gases in the sample. Theextracted gases are passed over hot uranium turninns(800-900°C) to reduce H ?0 and hydrocarbons to H. , thencollected in a calibrated volume, and the compositionfinally determined by mass spectrometer. This methodhas produced much lower and more consistent blanks.

2 .2 .5 See CRNL-160-7

- 32 -

PR-CMa-11

2.2.6 General Analyses- R.W. Ashley, P. Hardy

(1) Determination of Aluminium using the SpecificFluoride Ion Electrode"

Modifications have been made to the method reportedby Jaselskis and Bandemer (Anal. Chem. (1969) , 4JL, No.6,855) for the determination of micro amounts of aluminiumusing a fluoride ion electrode.

In the procedure developed, aluminium is titratedwith standard NaF solution in a system buffered to pH3.8 with acetic acid-sodium acetate. Down to 10 yg Alcan be determined with a precision of about ±2%.Normally only 10 ug Çe+3 can be tolerated in thisdetermination. However, the addition of 2.0 ml 4%thioglycollic acid and 0.4 ml 2M sodium acetate permitsthe determination of aluminium in the presence of 500ugFe + 3 with only a 2% positive error. The presence of500ug Cr+3 causes about a 4% positive error in theapparent concentration of aluminium at the 50 vr level.Other interfering elements are Zr and Be.

2.2.7 Service Analyses

Received From

Applied MaterialsResearch

ChemicalEngineering

Type of Sample mctal No.of

Zr alloysZr creepspecimensZr alloysTitaniumMonelSolderGentillycondenser tubeZr-Mo alloy

Decrudding soins.Crud soins.Swipes from DouglasPoint end fittingsU3SiLoop waterGraphite bearings

Samples

10

124431

12

3 426

21

163

Type of AnalysesDone

Identification(X-ray)

F, general spectrog.H2, D2, O2, SnH,-CoPb, Sn, Cl

Cr, Ni, General spectrogMo

General spectrog.Fe, Ni, Cu, Cr

Li, qenera.l spectrog.O2SOMGeneral impurities(X-ray & emissionspectrog . )

- 33 -PP.-CMa-ll

Received From Type of Sample Total Nr.. Type of Analysesof Samples Done

FuelEngineering

FuelMaterials

MetallurgicalEngineering

EngineeringResearch

GeneralChemistry

MaterialsScience

Mech. Equip.Development

ReactorLoops

R. & I.S.

UO

Zr alloysFuel elements

U-Al alloy

U3SiGraphite

Deposit onalumina tubeUranium soins.Oxidized U3Si

ZirconiumZr-4ScaleSteel

Pb-Bi alloy & U3SiHeater sectionfrom Pb~Bi loop

Pb-Mg alloy

Lead

Niobium

St. Lawrence Riverwater(Gentilly)

Metal deposits onpaperThO2

Mg soins.Na soins.

Zr alloy

U-l decontam.soins.

Swipes

1

87102

1

64

161

4111

3

6

6

2

4

2

761028

1

10

35

Fe, Ni, F, O/U andgeneral spectrog.H2, D2

Filling gas, totalH2 in fuel pellets,O 2 / H2, N 2, C insheathU

Nj, general spectrog.Evolved gases,total H2

General spectrog.USi

H2

General spectrog.ClTi

Si, U

Mg, Fe, Cu, Ni,Sn, Sb, Cr, O3,Pb/Bi ratioPb, Mg, Fe, Ni,Cu, Sn, SbO 2, As, Cu, Fe,Mq, Sb, Sn, ZnN2

Cl, NO3, SO,

Au, Pt, Pd, CrGeneral spectrog.MgNa

Identification(X-ray)

Fe, Ni, Cr, Co

Be

- 34 - PR-CRa-11

Received From Type of Sample Total No. Type of Analysisof Samples Done

NeutronPhysics

NuclearPhysics

AcceleratorPhysics

Proton BeamEngineering

E.I. & P.

Power Projects

OntarioHydro

HematiteBaTiO 3

TitaniumTitanium

Alumina ring

Cutting fluid

Scale from Kempair dryer

Water additiveDeposit on coolingside of Gentillypump heat exchangerSludge from base ofcooling tower

Sludge from NPDsteam drum

21

71

1

1

1

1

1

1

2

General spectrog.General spectrog.

D2General spectrog.

Identification ofStain (X-ray)

s

General qual.(X-ray)

Identification ofdeposits

Ni, Fe, Cr, Cu,Zn, Pb, Mn, Sn,General X-ray

Total number of samples = 491

Type of Analysis

SpectrographicX-ray FluorescenceAtomic AbsorptionGas AnalysisOther

Number of Analyses

10077524151176

2.. 3 FUEL ANALYSIS

2.3.1 Molybdenum as a Burnup Monitor- R.w. Durham

The controlled potential coulometric analyses oftotal stable molybdenum fission products from an irradiatedTh°i/3535U f u e l w e r e r e P ° r t e d i n PR-CMa-10. The r- - _rsof u and 2 3 3u fissions per gran of fuel have now beencalculated from the uranium chemical analysis and the

~ 3 5 - PR-CMa-11

isotopic ratios of the uranium atoms provided by theMass Spectrometry group. These values for numbers offissions of each kind have been converted to total Moproduced from the 95, 97, 98 and 100 chains. Molybdenumyields for 2 i 5U and 2 3 3 U obtained by W.J. Malck et al(IN-1277) by isotope dilution mass spectrometry wereused in the calculations and these yields carry mostweight in the assessment of fission yields by W.H. Walkerquoted in PR-CMa-10. The analytical results are given infable 2.3.1.1.

TABLE 2.3.1.1

Fuel Z 3 5U fissions 2 3 3 U fissions Mo concn.Element per g. fuel per g. fuel mq/g fuel

predicted found

THE 99 16.25 x 10 ! B 10.27 X 10'8 1.008±.020 0.889^.008

The coulometric results are based on duplicate analysesof four samples of fuel and although they show goodprecision are about 12% lower than expected from theuranium isotopic change results.

The results of similar analyses of an outer elementfrom the same flux peaking rod reported in PR-CMa-10showed a similar discrepancy. It is unlikely that thefission yields could be high by this amount, but on theother hand the coulometric Mo analysis has been thoroughlytested with standard Mo solutions. It is possible thatMo has diffused out of the fuel, but unlikely as the heatrating, /Ad6, would have been less than 25 watts/cm.

The development of a colorimetric method for Mo inthe 10 H- range using phenylflurone has continued. Abuffer hci~ been sought which will hold the pH at 2.0 toovercome the large swings in absorbancy caused by slightpH changes. The main difficulty is to obtain bufferingaction in acetone solution at such a low"pH, but somecontrol has been obtained using 0.1 M glycine - 0.17 M NaCl- 0.1N HCl in 50% acetone-water solution. The curves ofabsorbancy versus quantity of Mo in 50 ml using 5 cm cellsstill show a random variation in slope of about 5% inthe range 2 - 10 pg Mo. So far the work is being done todiscover the reason for this. Reduction of the Mo(VI) toMo(V) with hydroxylamine before color development had noeffect on the absorbancy. Thus it appears valency changesare not a problem.

- 36 - PR-CMa-11

2.3.2 Half Life of 23"U- R.W. Durham, M. Lounsbi-r- and B.C.M.N. Euratom

A joint program to determine the half life of 231tUhas been started. Uniform sources of uranyl acetate havebeen prepared at B.C.M.N. by electrospraying using NBSstandard reference material U-930 as a source of ! 3"u.The sources have been a-counted at B.C.M.N. in a low-geometry chamber and will be dissolved here and spikedwith known quantities of 2 3 BU for analysis by massspectrometric isotope dilution.

The sources are being u~counted before dissolutionand good agreement with the B.C.M.N. results has beenobtained. The low-geometry counting system has beenmodified in order to obtain better counting statistics.In the past only one integral number has been availableof the number of counts occuring during the long timeperiod (>16 hrs.) necessary to obtain good statisticalcounting. A readout system developed by W.D. Howell,E.C. & I. Branch, is now being used which provides areadout every hour on punched tape via a teletype. Aprogram for the G-20 written by T.T. Tan, Mathematics& Computation Branch, provides a fit to the data, standarddeviation of the mean and a plot. Preliminary operationof the system showed a gradual decrease in counting ratewith time which was found to be due to a gradual leakin the Ward chamber. This effect could not be detectedin an integral count.

Another low-geometry counter has been built usinga large (400 mm2) silicon PN junction type detector.The geometry of this counter is almost identical withthat of the Ward chamber, but because it is evacuatedduring counting there is no possibility of energy loss bycollision of a-particles with gas atoms. The geometryhas been determined by precision measurement of apertureand source distance, but the disintegration rate of astandard 2 U 1Am source is about 1% lower when measuredwith this counter as compared to a Ward chamber. Thereason for this discrepancy is being investigated.

2.4 RADIOACTIVITY MEASUREMENTS

2'4.1 Adsorption of Tellurium - Laboratory Studies- W.J. Edwards ~'

Recent work on the adsorption of tellurium byhydrous nickel oxides has been directed towards theconstruction of chemical and mathematical models forthe adsorption process, and fitting these to experimentaladsorption data. These data, summarized previously in

- 37 - PR-CMa-11

PR-CMa-10 Sec. 2.4.3 for a Ni(OH)2 substrate have beenextended to higher pH values and are shown in Figure2.4.1.1. It is seen from Figure 2.4.1.1 that the telluriumadsorption ratio (Te on substrate/Te in solution) dropsrapidly with increasing pH to pH=4.5, then remainsindependent of the solution acidity until pH=9.5 afterwhich the ratio again falls rapidly.

Attemps to fit a secondary, or counter-ion, exchangemodel to the observed data have not been successful. Inthis model the prior adsorption of a proton, or alterna-tively the removal of an 0H~ group from the surface by aproton, is assumed to occur first to provide a positivelycharged site for the adsorption of the anion of the acidused to control the pH. Exchange between this anion andtellurium anions provides the mechanism of telluriumadsorption. This model can be fitted at either end ofthe adsorption ration curve where adsorption is fallingrapidly with pH but fails to predict the existence of along pH-independent central region. This limitation occursbecause the extent of ion exchange is a linear function ofthe number of charged sites which decreases logarithmicallywith pH.

Althouc*-- neither the secondary ion exchange norprimary ior xchange models, which predict adsorptionproportional to the extent of positive charge developedon the substrate by loss of surface 0H~ groups, have beensuccessful, the adsorption of tellurium anions does suggestthe existence of positive charge on the substrate particles.Accordingly a search has been made for evidence of theexistence of such a surface charge. The method employedhas been the potentiometric titration of a suspensionof Ni (OH)2 by dilute nitric acid. This titration wascarried out using very pure water (pH 6.8-7.0) in quartzvessels in a CO2-free atmosphere. The results are shownin Figure 2.4.1.2, where the acid consumed is plottedagainst the pH of the solution. The acid consumed wasdetermined from comparison with a similar titration of apure water blank. The difference in pH between thesuspension and blank for a given amount of added acidis the acid consumed, after making allowance for thedifferent degrees of ionization of the water itself atthe pH levels.

It can be seen that there is a distinct break in thetitration curve centred at about pH 4.5. This may beinterpreted in terms of surface charge by assuming thatthe surface of the Ni(OH); substrate particle consists of(OH~) groups, some of which dissociate giving 0H~ insolution and leaving a slightly charged particle. As acidis added the 0H~ groups in solution are consumed and theionization equilibrium shifts to produce more free OH" groups,further charging

! 0 0SORPTION OF Te by Ni(OH)2 TiTRATION of Ni (OH)2 SUSPENSION WITH 0.0IN HNO3

lO.Omg Ni(OH)z

SUSPENDED in 25.0 ml.SOLUTION

100

5.5 65 75PH of SUSPENSION

30.01 mg Ni (0H!? in ZSLOIHI. H20

Figure 2 . 4 . 1 . 2

5 6 - 7

PH of SOLUTION10

PR-CMa-11

the solid particle. Eventually the particular charge issufficiently high to prtvent further loss of surface OH~and the addition of more acid simply lowers the solutionpH. According to Figure 2.2.1.2 this would representthe situation at about pH 5. Continuing the additionof acid results in a falling pH and an increasing concen-tration of the acid anion (in this case NO3~) in thesolution. When the concentration of the anion of theacid becomes sufficiently high the N 0 3 ~ groups begin tocombine with the "vr.rged surface groups and sequester them.This requires a fairly high concentration of nitratepresumably because of the great solubility of nitrate salts.

As the positive surface sites are sequestered theresulting drop in particle charge again permits theionization of 0H~ groups. Accordingly the consumptionof acid again rises with fallinq pH.

Thus, the titration curve can be interpreted asevidence of the production of a surface charqe up to alimiting level, but the rapid drop of the curve abovepH 5 suggests that adsorption of tellurium ions cannotbe a linear function of the number of charged sites.These """^nsiderations suggest the following model for theadsorption process.

A portion of nickel hydroxide substrate having asurface 0H~ group is written as "S-OH" where "S" representsthe weight of Nj (OH) -. associated with one no le of surface0H~ groups. The ionization of the substrate as a weakbase is then given by equation (1) with the symbol .S +

representing an equivalent weight of charged sites onthe substrate surface.

We now assume that the anion to be adsorbed is theanion of a very weak acid and write its lonization asequation (2). The adsorption reaction itself is thenrepresented by equation (3) with the additionalassumption that the surface adsorption product, S-A, isalmost ''insoluble", i.e. very slightly ionized.

The three reactions are summed to obtain the overallequation for the adsorption reactions, equation (4), andits corresponding equilibrium constant, K e«.

(1) S-OH t S+ + OH"(2) H-A ï A~ + H +(3) S + + A~ % S-A

4) S-OH + HA \ n-A + 11,0

- 40 - PR-CMa-11

Note that although adsorption proceeds via the surfacecharge, S+, it is independent of its extent. Thedegree of dissociation in equation (1) may affect therate of adsorption however.

It is instructive to enquire as to what theexpected shape of the adsorption curve will be under agiven set of experimental conditions. The conditionsare chosen such that the total concentration of theanion to be adsorbed is much less than the ultimatecapacity of the substrate i.e. ([HA] + [A]) ^<[SOH].

Consider a pH range such that [S+j <-• [SOHJ, whichis probably true down to about pH 5. In this range,because [HA] has been defined as small the [SOHJ willtherefore be substantially constant and from Keq we

see that the ratio 1 — must remain constant with pH.I HA j

This is essentially what is observed over a large pHrange for the adsorption of tellurium anions onNi(OH)2. On the other hand, although HA has beenassumed to be a weak acid, its concentrationwill drop at high pH. The rario [SA]/[HA] must alsofall to maintain Keq. In strongly acid solutionhowever [HA] will be constant but the equilibriumof equation (1) will shift to the right so that thecondition [SOH] << [S+] is no longer true and [SOH]will begin to decrease significantly.

By itself, this decrease will bring about a dropin the absorption ratio. However, in order to lowerthe pH a new anion, that of the pH controlling acid,must be introduced into the system. The disappearanceof the "S-OH" groups corresponds to an increase inthe adsorption of this anion, together with thelimited increase in the surface ionization discussedearlier. A new equilibrium corresponding to (4)is then possible with the [SOHJ term replaced by theadsorption product of the pH controlling acid.Whether the adsorption ratio [S-A]/[HA] will rise orfall in the region of low pH, then, will depend onthe relative stability of the "S-OH" group comparedto that of the anion of the pH controlling acid.In the present experiments nitric acid has beenused for pH control and the curve for the adsorptionratio rises in acid solution for a nickel hydroxidesubstrate (Figure 2.4.1.1).

4 1PP-CMn-1]

Note that the hypothesis that the acid, HA, nuptbe very weak is not a criterion for the adsorption ofA", but is a necessary requirement if the adsorptionratio, [SA]/[HA] vs pH curve is to have a lonq pllindependent portion. If the anion A~ forms a strongacid, which is completely ionized at all pH valuesunder consideration, adsorption can still take place.Under these conditions the expression for Keq wouldcontain an [OH] term. The adsorption ratio wouldthen be expected to drop exponentially with increasingpH.

The extent of adsorption i.e. the magnitude ofKeq should be a function of the relative stability ofthe SOH and SA surface groups and probably approximatelyequivalent to the solubility ratio of the pure anionsalt and the hydroxide. This process involving thesurface precipitation of a weak acid by an "insoluble1

weak base is somewhat analogous to the theory ofbuffered solutions. It accounts for all the phenomenaobserved to date and in principle can predict theadsorption ratio of an anion from published values ofdissociation and other pertinent constants where suchdata exist.

The model postulated above makes a number ofpredictions which are capable of experimental test.Among these are:

fl) The value of Keq should be simply related to therelative solubility of Ni(OH), and the nickelsalt of the anion to be adsorbed.

(2) The pH at which the adsorption ratio beams tofall should be a simple function of thedissociation value of the acid " H V .

(3) The pH at which the adsorption ratio begins toincrease will be lower, the .smaller the dissociât.]constant of the substrate.

Work is continuing on the mathematical andexperimental tests of this model.

- 42 - PR-CMa-11

2.4.2 Counting Room

This quarter has seen a very marked increase in down-time due to failures in our PDP-8. This is attributed toelimination of preventive maintenance and greatly increaseddelays in answering service calls. A direct consequencehas been that, in an effort to maintain continuity ofservice a great deal of the group's effort has beenutilized in fault diagnostic procedures to facilitateservicing.

A total of 510 samples were received in the period.These were analyzed as follows:

Decay curves beta 13gross beta 169

Nal(Tl) gamna spectra 237

Distribution of Beta Analyses

X-l X-2 X-3 X-5 X-6 U-l

DecayGross

Loop

258

251

128

72

Distribution of Gamma Analyses

X-l X-4 X-5 X-6 X-7 U-l

18 84 20 60 19 47

NRU NRXLoops,General

95 71

Douglas Misc.Point

18

U-2

128

U-2

22

Spec.Anal.

95

NPD

23

TeSorption

154

2.5 HEAVY WATER ANALYSIS

2.5.1 Natural D/H Range- W.M. Thurston

(a) Analytical Developments

(1) Steam Probe - The liquid to Vapour samplingconcept referred to in PR-CMa-10 makes use of theLeidenfrost effect which permits the formation of astable steam blanket under the end of a hemisphericalmetal tip immersed in water. The stable film-boilingthat exists if the metal is above the critical temperature(where the liquid no longer wets the metal) produces aliquid to vapour conversion with no transfer of dissolvedsalts or particulate matter.

4 '' PR-CMa-11

A hot probe in stable operation at 30n°C is shownin Figure 2.5.1.1. The photooranh was taken looking u\>at the underside of the surf-ice. \ back drou of parallellines indicate the extent of surface distortion, about3 probe diameters or 18 mm.

Successful probes have been nade fron silver, brass,gold, and nickel and the present ain is to reduce the tipdiameter from 6 mm to 2 mm to minimize sample heating andpermit sampling of small drops of water.

A rugged and compact controller and probe assemblyhas been produced in the instrument laboratory of COE atPeterborough, and one of the assemblies is now tied intothe mass spectrometer at Port Hawkesbury.

(2) Infra Red analysis of D/H in Water - A newInfra-Red cell has been designed and built that permitsthe accurate intercomparison of sannle and referencestandard. The concept is similar to the "Flip-Fion"cell developed here m 1963. However, the sapphire cellbody is now outside the spectrometer housing for easyinspection of the sample area. The 4 mm sapphire disc onwhich the cell is built gives good heat transfer betweenthe standard and sample compartments permitting D/IIanalysis using the HDO absorntion peak at 2500 CM~1.The precision of the analysis is about r2 ppm.

(b) Heavy Water Plant Assistance

Both Items 1 and 2 above have been deveJoped for usein Heavy Water Production Plant Laboratories. The infra-red cell has been redesigned into a rugged, reliable,and interchangeable slip-in assembly, for use on theinfra-red spectrometer and will provide reliable instrument"back-up" for a D/H Mass Spectrometer.

^c^ Future Analytical Requirements '.D/H analyses)

A survey is being carried out to examine closelythe characteristics of all mass spectrometers capable '••;.analyzing water and hydrogen for deuterium content atlow D/H ratios ('10 to 500 x 10"'). CRNL has only oneinstrument capable of 0.1% precision for this analysis.As a result of recent developments in ll.Q-H, catalyticexchange m particular, day-shift usage of the ThompsonHouston THN202 Mass Spectrometer has reached saturationsooner than expected. Additional instrumentation willbe required shortly to prevent hold-ups in analyses mpresent programs.

- 44 - PR-CMa-11

Figure Z. 5. 1. 1

PR-CMa-11

Summary of D/H Mass Spectrometer Analysis

No. ofSamples

80297<642726

6354

General ChemistryGeneral ChemistryChemical EngineeringChemical EngineeringChemical OperationCanadian GeneralElectricEnvironmental ResearchMiscellaneous

Steam Probe DevelopmentH2-H2O ExchangeContactor ExperimentsExchange ExperimentsErco Experimental Cell

Heavy Water Plant FeedWater Survey

3227*0n-line automatic Hydrogen analysis

2.6 ELECTROCHEMICAL H/D SEPARATION

2.6.1 Electrochemical H/D Separation- M. Hammer 1:~ W. J . O Ins te ad

(a) Bendix MA-1 Mass Spectrometer

During this period much nas Been learned aboutoptimizing operation of the Bendix "tA-1 time-or-f lightmass spectrometer for the determination of D/H ratios.The following observations were made:

1) 1% deuterium gas standardf

D/H ratio analyses ofvaried as much as 10*. during the course of a dayin a direction such that one suspecte:! crosscontamination with a substance nf much lowerdeuterium content. This effect, was not dependenton the temperature increase within the analyzerwhen the filament current was turned on. Testc

showed this effect is a function of the number :dry hydrogen samples which have been analyzed.Once the mass spectrometer has been conditione..with dry hydrogen gas samples, such samples tr-xlucelittle or no memory effects, n.g. a^ernate analysesof a J 08 ppm and 2 0,000 ppn deutenur standard

Th l r. behaviourat natural

pprn and 2 0,000 ppnwere reproducible and accurate ( <lr*).suggests the presence of adsorbed waterdeuterium concentration inthe mass spectrometer doesovernight, there probablyHelium test ing indicated aconnecting the plug box a.-housing. Therefore, thewi l l be replaced with a gold

the analyzer. Sincenot renain conditionedv a snail leak somewhere.s r a l ] leak .-round the flange

.-^erib] ln the amiy7.p>copper aasket at this tJangt?

qasket, and the analyzerhousing will be heated externally with the ain ->freducing this conditioning ef fec t .

- 46 - PR-CMa-11

(2) On our system unsatisfactory D/H analyses of batchwater samples (introduced i-o the mass spectrometervia a heated inlet system and a uranium furnace at600°C , both designed by W.M. Thurston) are obtained.Memory effects and pump-out times were both toolarge. By using Thurston's steam probe in conjunctionwith the hot uranium furnace, however, satisfactoryD/H analyses were obtained with 143 and 253 ppmdeuterium water standards. These analyses, in contrastwith the batch samples above, showed all thecharacteristics of dry gas samples. However, theevaporation rate of the surface and sub-surfacelayers was too great for this method to be practicalfor heavy water standards with larger deuteriumcontents. We expect that a much smaller probe nowbeing investigated by W.M. Thurston will overcomethis difficulty.

(3) Argon-hydrogen isotope samples from our electrolysiscell and gas collection system could not be analyzedsuccessfully. The results obtained suggest the G.E.triode ion pump (100 1/sec nominal capacity) cannotpump this gas mixture reproducibly. For example, thebackground pressure was much higher after eachsuccessive aliquot than is normally found. Also,during the third aliquot, the mass 2 and mass 3peaks increased in a random fashion when both shouldhave been decaying at a definite rate. This problemwith argon was not unexpected.

(b) Mass Spectrometer Inlet Systems

The direct inlet system and the batch inletsystem (see PR-CMa-10) have both been leak tested success-fully.

Work on the direct inlet system is progressingbut cannot be completed without breaking the vacuum inthe mass spectrometer. Meanwhile, a protective circuitincorporating a solenoid valve and a gold leak has beenconstructed for this inlet system since the analyzerassembly is easily damaged when suddenly exposed to anatmosphere of air.

The new batch inlet system worked well duringtest electrolyses, but the resulting argon-hydrogenisotope gas mixtures could not be analyzed (see item 3above). Therefore, an argon-hydrogen separator builtaround a silver-palladium thimble was inserted into thebatch inlet system. Preliminary tests have shown thatthis separator is effective. The rate of diffusion ofthe hydrogen isotopes is compatible with both shortelectrolyses and the automatic mass spectrometer inletoperation. Further tests are necessary to determine theextent of isotope separation,if any, and the magnitude ofthe possible memory effect within the silver-palladiumthimble.

47 -PR-CMa-11

2.7 SPARK SOURCE MASS SPECTROMETRY

2.7.1 Trace Analyses of Lithium - Drifted Germanium Semi-conductors- I.H. Crocker with I.L. Fowler and Ontario ResearchFoundation

Comparison of mass spectra produced from samplescut from four different Ge(Li) crystals showed that theone with the best detector qualities was also the onewith the lowest level of trace impurities. The levelsof P, S, K, Cr, Fe and Cu were all significantly lowerin the best detector than in the other three.

2.7.2 Determination of Impurities in p-Type Silicon Detectors- I.H. Crocker with D.A. Marsden

Small slivers of Si used as particle detectorswere sparked in the mass spectrometer. Their thinnessand brittle nature prevented long exposures anddeterminations to lower than the ppm level. The maximumexposure realized was 30 nanocoulombs. Ions wererecorded over the mass range from 7 to 226. Elementsidentified were H, C, N, 0, Na, Al, Si, Cl, K and Cu.

The elements H, C, N, and O are always presentas background in the source of the mass spectrometerand their concentrations in any sample cannot beestablished at present. Na and K are disproportionatelysensitive to spark source excitation because they havevery low ionization potentials. The remaining impuritiesfound were present in the following concentrations:

Al '• 12 5 ppmCl was variable with depth, decreasing from

a surface maximum of - 1800 ppmCu - 1 ppm

Interpretation of the spectra for this sample wasmore than usually difficult because of the number ofmultiply-charged and complex ions which were formed inthe sparking process. A partial list is as follows:si+++, si++, si7+, si,+, si.+, si»+, si,+, s i + , sih+f

SiO+, SiN+, C,HSi+, CHSi,+ , CI1.+ , CH.+ , CH+, C,H.4, C ..H ,C3H,+ , C5H5+, C,H, + , CJH +, C.H.t, C . Ï U + , C.H. + , CH,+ ,CvH9+, CH.B+, CiHe

+, C5H,+ , C < H . „+, C,H,, + , and OH,. 4.

These ions were identified either by their isotopicpattern or by their exact position on the nass scale.The resolution of the mass spectrometer was adequateto resolve the mass doublets formed with the abovehydrocarbon ions.

- 48 - PR-CMa-11

..7.3 Environmental Sample Analysis- I.H. Crocker, L..W. Wray with W.F. Merritt

Samples of evaporated Perch Lake water are analyzedon the spark source mass spectrometer for tracecontaminants. A slurry of the solids residue is appliedto Ultra-carbon electrodes whose impurity backgroundhas been previously determined. A spark is drawn throughthe residue between the electrodes thereby ionizing theelements comprising the residue. This work is in itsvery early stages and no significant results are as yetavailable.

2.7.4 Liquid Metal Coolant Analysis- I.H. Crocker, L.W. Wray with R.B. Turner, R.W. Ashley,

W.D. Mackintosh

Six samples of Pb-2.5% Mg alloy taken at temperaturesfrom 300°C to 535°C were examined for their impurityconcentrations. They were all run on the mass spectro-meter for a sufficiently long time to enable detection ofppm impurities. In addition, the 300°C and 535°C sampleswere run more exhaustively to see if the samples takenat the temperature extremes would display detectabledifferences in impurity concentrations at the sub-ppmlevel.

Elements detected in each sample were Al, Si, Cl,Fe, Cu, Zn and Ag, plus H, C, N and 0, the usual back-ground quartet. Table 2.7.4,1 is a record of theimpurity concentrations found in the 300°C and 535°Csamples.

TABLE 2.7.4.1

Spark

No.

12345678 '9

1011121314

Source Mass

Element

AlSiClKScMnFeNiCuZnZrAgTlBi

Spectrometer Analysis of Pb-Mg

Concentration(ppm by•l. 300OC #6.

0.31.5.10.50.50.52<0.330.7<0.14.5<0.1<0.1 -

Alloys

weight)535°C

0.26.50.20.2o.;0.91.5<0.482<0.213<0.1<0.1

- 4e» -PR-CMa-11

Some of the elements were also determined by otheranalytical techniques. The comparison with spark source?mass spectrometry results appears in Table 2.7.4.2.

TABLE 2.7.4.2

Comparison of Analytical Results from Mass Spectrometry,Neutron Activation, and Atomic Absorption

Element Other Method Impurity by Impurity byOther Method SSMS, 5 3 5°C•10 0C-C Sample and 3 0 0°c(ppm by wt.) Samples

(ppn by wt. )

Zr activation araLysis >1 -0.2Fe atomic absorption •2 2Mi " " 2 0.4Cu " " 5 3-8

Two elements, Sn and Sb, are not reported herebecause their concentrations in Pb-Mq alloy are stillin doubt. Determinations of these two elements bySSMS have been consistently lower than by otheranalytical methods and we are attempting to resolvethas discrepancy.

2.7.5 Standardization and Calibration of SSMS- I.H. Crocker and L.W. Wray

A series of measurements of a Bureau of AnalyzedStandards mild steel spectroarahpic standard ïSS-60 wastaken to assess the relative sensitI":ty factors (R.S.F.)for seven elements in an iron matrix. The results appeal'in Table 2.7.5.1.

TABLE 2.7.5.1

Relative Sensitivity Factors for SSMS*Mild Steel Spectrographic Standard 5S-6 0_

Element 3 Mn V Fe Co Cu S!> Pl>Concentration(wt.%) 0.007 0.45 0.027 MATRIX 0.020 0.047 0.018 n.nm

Relative SensitivityFactor (R.S.F.) 1.6 2.7 1.') 1.0 ^.0 1.7 l.ft 3.R

Standard DevQ(%) 30 16 II 0 15 2Î n 1 r>

*SSMS parameters: accel. V in.3 kV; rf in k";pulse rate -- 3 00 cs~ ;pulse Jenqth - 100 rr 2no . s;ion beirr clnijpur was

- 50 - PR-CMa-11

The above results compare reasonably well withothers that have appeared in the literature, keeping inmind that factors obtained on one instrument are notconsidered to be directly applicable to another. Someof the published results are compared with values thatwe have obtained in Table 2.7.5.2.

TABLE 2.7.5.2

Comparison of R.S.F.'s for Iron-based Alloys

Element RSF(CRNL) Std.DevE(%) RSFfShort & Keene*) Std.DevIl(%)1966

B

Mn

V

Fe

Co

Cu

Sb

Pb

1.6

2.7

1.9

1.0

1.0

1.7

1.8

3.8

30

16

11

-

15

21

33

19

3.1

3.0

2.1

1.0

0.74

1.6

6.4

42

17

31

18

15

44

•Short, H.G., and Deene, B.J., Talanta _13_, 297 (1966)

2.7.6 GEC/AEI 702 Mass Spectrometer- I.H. Crocker and L.W. Wray

Operation of the mass spectrometer has continued tobe satisfactory. The manufacturer has promised to installthe electrical detection accessory in January, 1970.Improvements in ion detection by photoplate are beingsought constantly, however.

One of the factors influencing the accuracy of sparksource mass spectrographic analysis is the processing ofthe spectrographic plates which must be even and consistent.A tank for the processing of these plates has been builtbased on a design by E.B. Owens (Rev. Sci. Instr. 32,1420 (1961)). It provides for mechanical agitation ofthe plates and thermostatic control of developingtemperature. Plates processed in the tank appear clea \and evenly developed. Some improvement in temperaturecontrol is necessary.

- 51 " PR-CMa-11

2.8 MASS SPECTROMETRY

2.8.1 NRU Thoria-Urania Flux Peaking Rods- M. Lounsbury

Mass spectrometric analyses of samples from NRUFlux Peaking Rods used to test the LATREP computerprogram to predict the change of reactivity of thcriumfuels with irradiation were last discussed in PR-CMa-5,Section 1.5.1. The previous work (at 46 30 MWd/Te)resulted in modifications to LATREP which gave agreementto ±1.7% on average, between the mass spectrometricmeasurements and the LATREP predictions of the isotopiccomposition of the irradiated fuel. The fuel initiallyconsisted of 98.5% ThO2/1.5% UO2 with the uraniumenriched to 93% U-235, and was assembled in li;>-elementbundles.

Further mass spectrometric analysis have now beencompleted on samples provided by the Fuel Analysis Groupfrom Pellet 99 (inner ring) and Pellet 98 (Outer ring)in the axial centre of Bundle THE. The nominalirradiations of these two pellets are 11,360 MWd/Teand 16,6 50 MWd/Te respectively end thus they providea more rigorous test of LATREP at the higher irradiations

The LATREP computations (by M.F. Duret, AppliedMathematics! are not yet completed, but the massspectrometer results are listed in Table 2.8.1.1.

TABLE 2.8.1.1

Uranium

Pellet No.

MWd/Te

At. % 233

234

235

236

238

Isotopes

0.000

0.783

93.017

0.235

5.965

42

0

•

•

•

±

, , NRU

0. 000

0.002

0.011

0.002

0.010

Flux Peaki.

99

11,360

49.39

2.990 '

34.18 •

7.943 ?

5.497 +

ng Bund

0.09

0,008

n, 08

0.020

0.014

lc THE

57.

4.

24.

8.

5.

98

16,1

14

138

58

93 2

213

50

• 0 . n f>

' 0.011

• 0.06

' 0.00e»

i 0.014

- 5'. - PR-CMa-11

2.8.2 2200 m/s Cross Sections of Fissile Nuclides~ M. Lounsbury (with R.W. Durham and G.C. Hanna)

Some small changes have been made in the resultsof the Bismuth Rod Experiment quoted in PR-CMa-9,Section 1.5.1 as a result of minor revisions in thevalues of Pu-241 and Pu-242 cross sections used in theinterpretation of the mass spectrometric measurements.In addition, Hanna, Westcott et al (Atomic Energy Review,in press) have completed their survey of the recommendedvalues for the 2200 m/s cross sections of fissilenuclides. In Table 2.8.2.1 the values obtained fromthe Bismuth Rod Experiment (see PR-CMa-4, Section 1.5.2)are compared with the new recommended values.

TABLE 2.8.2.1

2200

Quantity

a(233)

a(235)

a(239)

oa(239)

m/s Constants for

Reco.!iunendadValues

0.0885 ± 0.0018

0.1694 ± 0.0021

0.3659 ± 0.0039

1012.9 ± 4.1 b

Fissile Nuclides

ExperimentalValues

0.0899 ± 0.0004

0.1702 ± 0.0007

0.3601 ± 0.0021

1017.0 ± 6.4 b

g-factorUncertainty

±0.0017

±0.0020

±0.0045

±2.9 b

2.8.3 Separation of Lithium Isotopes- M. Lounsbury

Dr. S. Sourirajan, Chemistry Division, NRC, Ottawa,is attempting to separate the Li-6 and Li-7 isotopes ofnatural lithium by a reverse osmosis technique usingcellulose acetate membranes. In order to determine ifthe process is feasible, he has submitted three samplesof LiCl for mass analysis. These samples representthe starting material, the product which passed throughthe membrane, and the residue which did not.

The isotopic analysis of lithium by thermionicemission mass spectrometry is, in principle, easybecause of the low ionization potential of lithium,but in practice it contains pitfalls for the unwarybecause of possible isotopic fractionation of the sampleduring the evaporation process. With lithium thisisotope effect is particularly vexing because of the

> PP-CMa-11

large (17't,1 percentaac nriss difference between the.' t\-Misotopes. Because of this, reported values of thenatural Li - 7 - I.1-6 abundance ratio ranqe ovor severalorders of mai.init.ude, iron a mininum of 2 to a raaxi^ur:of 130.

The problem is less difficult with our triplo-filament thermionic source because one can choose arefractory material of higher molecular weight for theevaporation step, toi lowed by dissociation on a hightemperature surface. Fron this point of view, of thetwo compounds normally used in thermionic emission,the sulfate is preferable to the nitrate because,tl) its higher molecular weight reduces the possibleisctopic fractionation and (2) its higher meltingpoint reduces the possibility of evaporation from theliquid state, with resultant increased fractionatinn,and it also reduces the possibility of memory effectin the mass spectrometer fron previously evaporatedsamples. This problem can \>c serious because nf thehigh 1on.Lzat1.on efficiency of lithium.

The method of isotopic analysis adoptedwas to deposit 2 m: crocirams of lithium as the sulfateon one of the pair of v a o o n z i n q filaments ind tovaporize tn.e sample only by thermal radiation from thecentral lonizjuq f 1 lament. The ion 1. zing filamentis operated at the lowest temperature which wi11 aivesufficient ion current.

Results to date indicate that all three sampler,have approximately the samp isototur composition, andthus the rovt'fci cv-'iosis tt.'clmi'i'io, ! rori this run,does not ippoar pr^misina. In addition, all threesamples were about 1S ' depleted in Li-(i. 'Miviou.-ly,the starting material had go no through the U . N . A . K .(..'.process for the separation of 1. • - fr . Lithium compounds,as marketed by trie chorucdl industry have, for morethan a decade, l.'ten of altered isot.Of-ic compos Ï t11"1.:,to the extent that even the molecular wought and thegravimetrjc factens arc appreciably affect.ed. Asample of Baker and Adams >n lithium sulfate (lot No.N-1G8) from Chemistry Store-, sh'v.-;ea a 50* depletionof lithium-6.

Further work is required t.< - noteniri'.' the ••l.uin 1 t. IKI<>of any possible memory oft curt.1, or îsctoiui' ' 1 a .'t 1 o n t1 enm the mass s p o f :omotric an.iJvsih. inic ua^: Iv whichwas deliberately sub lerti/d to !i 4 ih. t ui'uu-r.i t uro con.i ; t 1 cui'in the ion source s)u;w"i.! .1 f'ir t !•..-.• 1 I1)' d-'1! l«'t i:<r. 1 i\ l.i-(-It has not yet bcuri I M M W I , .-. ;n.t !pl ; this va ; « i u > • t -conversion ot the; ^ o l M l f in' t hi :-.i.-ta! "P. Lh^ -• IP. •!'1 / 1 Ifilament, or to e",n >ur .11 i on ti-'.r 1 he !n:'inl (--t. stc witliloss of about 80 < oi the

- 54 - PR-CMa-11

Burnup Measurements- W. Cherrin and J.A. Schruder

Uranium mass analyses of twenty-six samples ofstarting material and irradiated fuel, and plutoniummass analyses of seven irradiated samples were determinedfor burnup calculations.

2.9 REPORTS, PAPERS AND PUBLICATIONS

2.9.1 Conference Papers

(1) Automatic Mass Spectrometric Analysis of theDeuterium Hydrogen Ratio in Natural Water -W.M. Thurston. Presented at the 16th SpectroscopySymposium in Montreal, October 20-22, 1969.

- 55 - PR-CMa- 1 i

3. REPORT OF PHYSICAL CHEMISTRY BRANCH

by

D.R. Smith

Pag c

3 .1 STAFF ^

3.2 RADIATION CHEMISTRY ,73.2.1 Pulsed Electron Radiation Chemistry v;3.2.2 Pulse Radiolysis of Liquid Systems ()-\3.2.3 Electronics for Pulse Radiolysi.s ,,K

3.3 ISOTOPE CHEMISTRY t,H3.3.1 Optical Spectrum of Amine Solutions f,K

3.4 REPORTS, PUBLICATIONS AND LECTURES f,K3.4.1 Publications <>H

PHYSICAL CHEMISTRY BRANCH

3.1 STAFF

PR-CMa-i

Branch Head

Secretary

D.R. Smith

Mrs. J. McCorry

RADIATION CHEMISTRY

A.W. BoydJ.W. FletcherW.A. SeddonC. Willis

ISOTOPE CHEMISTRY

J.P. ButlerJ. Rolston3

P.E.O.A.P.J.R.W.M.J.J.A.

Bindner(Tg)Miller(Rt)Richards(TgRobinson(RtYoung(Tg)Reid1

J.J.

Denhartog(Tg)Goodale(Tg)

Jo ined December 29 , 1969 Water loo StudentJo ined October 1, 1969.

57 ' PR-CMa-1

3.2 RADIATION CHEMISTRY

3.2.1 Pulsed Electron Radiation ChemistryA.W. Boyd and C. Willis

(a) Mechanism of the Radiolysis of Gaseous Oxygen.

A large dose rate effect has been observed in theradiolysis of gaseous oxygen (see PR-CMa-10, AECL-3477).At 1 0 3 5 - 10s'' eV g ^ s " 1 , G(0 3) = 12.8 + 0.6 and at10 l B eV g ^ s " 1 G(0 a) = 6.2 ± 0.6. As has been suggested(1,2) the difference between the G values at the twodose rates can be explained by differences in theneutralization processes.

The effect of SF 5 and c-CÀFa on the ozone yieldsat the high dose rates is shown in Figure 3 .2 .1 . .1 . Bo'hthese electron scavengers reduce the yield to G(O3) =6.3 ± 0.6 which is the same as the low dose rate valuf.

Calculations based on rate constant data for ionicreactions in oxygen have shown that the predominantreactions at the high dose rates are neutralization of02 or 04 by e~ , 03 ~ , 04 ~. Increasing the pressure, 1 o.going from iOO - 1000 Torr, favours neutralization stepsinvolving 04 type ions but since there is no decrease inyield over this range all these neutralizations must c; 1 vesimilar products. Since these reactions are 140 - JMt1 Kcdmole exothermic with respect to the formation of ' wnoxygen atoms it is probable that dissociative-neutralization reactions such as r 1 "! will occur.

O4 + + 02 ~ — 2 0 + 2 0a 1 "

- 58 -PR-CMa-Il

O

JJ

LU

NJ 1.3Ci

IB

c1 2

8

4

—

>

X

—

1

v_X

1

I

o

1

0

1

1 _

1

xP

i

! 1 1

-

—

*°0 x

1 1 1

0.5 1.0 1.5 2.0 2.5 3.0 3.5

MOLE PERCENT A D D I T I V E

Figure 3.2.1.1The Effect of Electron Scavengers on the Ozone Yield in theRadiolysis of Oxygen at 700 Torr. Dose rate 2 x 103S eV g ^

0 SF3 , x c-C4Ft

- 9 -PR-CMa-1!

In the presence of electron scavengers (SF L,c-C 4F h ithe neutralization reaction will Dresumably b e :

0 4+ + S F S " —• 20 a i- SF 5 ' 2 1

The reduction in the yield should then be2 G(e) = 2 x 3.27 = 6.5 in good agreement with theobserved A G ( 0 3 ) of 6.5 ± 0.9. This is in contrast to thelow dose rate irradiations where the yield is notaffected by electron scavengers (3). Here, then, theneutralization process does not yield oxygen atoms. Atlow dose rates, for any reasonable dose, the predominantnegative ion in the system is 0;> formed by reaction " I 1

0 2 ~ + 0 3 — 0a + 0 ? ~ r 3 1

and the neutralization seep will be of the form

0 4 + 0 3 ~ —• 2 0a + 03 r4 1

That reaction [I"1 is dissociative whereas ' 2 1 andr4 ] are not, can be explained in terms of the electronjump mechanism (4). If neutralization occurs, beforecoalescence of the ions, by electron tunneling from arelatively large distance then the neutralization processwill not be influenced by the negative ion species norcan the energy of neutralization be shared with thenegative species. Such is the case in react ion rl "* butin reactions '2 "" and 4 1 differences in geometry hcHwer-nthe negative ion and its neutral form pi^hibit suchtunneling, e.g. the equilibrium bond angle for 0.. is ]u<)n

and for 0a is U 7 ° (5) .

References

1. C. Willis, A.W. Boyd and D.A. Armstrong, Can.J.Okem.

47_, 3783 (1969) .

2. A.W. Boyd, C. Willis, R. Cyr and D.A. Armstrong.Can.J.Chem. in press (to aupear Dec. 15, 19(-[M.

3. J.T. Sears and J.W. Sutherland, J.Phys.Chrm. 72_, II'''-

(1968) .

4. F.T. Chan, J.Chem.Phys. ±9_. 2533 and 2 5-4 1) (l')i.H).

5 . R . H . L e e , F . A . C o t t o n a n d G . W i l k i n s o n , A d v a n c e s i n

I n o r g . C h e m . 2 n d E d . I n t e r s c i e n c e , N . Y . 19Cu>.

- 60 - PR-CMa-1.1

(b) Energy Balance Calculations of the Ozone Yields inGaseous Oxygen.

Because oxygen is a simple homonuclear diatomicspecies and because the energy levels of most of itsionic and excited states are known it is worthwhileto calculate the proportion of energy going intoexcitation and ionization. For any system the W value,which is the mean energy per ion pair, can be equated toE. + È + Ë , where Ë. is the average energy forl ex subex 1ionization, E the average energy for excitation and

Ê the average energy of the subexcitation electrons,subex **

Using the potential energy curves of Gilmore (6) andthe electron cross sections of Watson (7) the value of E.for oxygen has been calculated to be 17.5 ± 0.3 eV. TakingË , to be 2.5 ± 0.5 eV (8) the energy available forsubex _ *J

excitation E = W - Ë. - Ê , =10.6 ±0.8 eV. Theex l subex

average energy required for dissociative excitation bytransition to 3I and 3 E ~ states of oxygen is 9.0 ± 0.5(9). The yield o¥ 0 atomsUper 100 eV then should be2 x 10.6 ± 0.8 xG(e) = 7.5 ± 0.9

9.0 ± 0.5The total calculated ozone yield from all processes isthen G(03) , = 14.0 ± 0.9 in reasonable agreement with

calcthe observed value of G(03) = 12.8 ± 0.6.

References

6. F.R. Gilmore. J. Quant .Spec .Rad .Transfer , 5_, 369(1965)

7. C.E. Watson, V.A. Dulock Jr. R.S. Stolarski andA.E.S. Green, J. Geophys.Res. 72_, 3961(1967;.

8. K. Fueki and J.L. Magee, Disc.Farad.Soc. 36., 19 (1963)

9. E.N. Lassettre, Can.J.Chem. 47, 1733 (1969).

PK-CMa- 1 1

(c) Radiolysis of Air and Nitrogen-Oxygen Mixturi-s

The yields of ozone m ihe irradiation of air andnitrogen-oxygen mixtures, at 7 00 Torr total pressure anda dose rate of 1.2 x 10a° eV g ^ s ' 1 , are shown in Figures3,2.1.2 and 3.2.1.3. No nitrogen dioxide was observed.The solid lines in these figures are the results ofcomputer calculations using all the known ionic andneutral reactions in these mixtures and the followingprimary yields; pure oxygen G ( 0LJ ) = 3.27, G(0) = d.2,pure nitrogen G(N P

+) = 2.9 and G(N) - 6.0.

The same input data were used to calculate 0-, andN0s yields as a function of dose rate. The results ofthese calculations are shown in Figure 3.2.1.4.

The predominant ionic reaction other than neutraliza-tion is charge exchange of No with 0B . The major reaction.,of N atoms are :

N + 03 — NO + 0

N + NO — N2 + 0

N + N + Na — 2N2

N + 03 —• NO + 0s

and competition between these reactions accounts for themajor part of the dose rate and pressure behaviours.

Detailed reports of the results, mechanisms ancicalculations for both pure oxygen and . m t rogcn-oxyqi-:.mixtures have been submitted for publication.

- 62 -PR-CMa-11

f-s!O

ta

300 400 500

PRESSURE (TORR)

600 700

Figure 3.2.1.2Ozone Yields in the Radiolysis of Air as a function of Pressure

Dose Rate 1.2 x 103S eV g^s""1

0 Air, x air + 0.5 - 2.0% SFa

- calculated yields.

-bi - I'H-CMa- ! !

ooCD

1 4 - 700 TORR PRESSURE

PARTIAL PRESSURE OF OXYGEN (TORR)

Figure 3.2.1.3Ozone Yields in the Radiolysis of Nitrogen-Oxygen Mixtures at700 Torr as a function of the Partial Pressure of Oxygen.

Dose Rate 1.2 x 10at: eV g^s" 1

0 Na x N2 + 02 + 0 . 5 - 2 . 0 % SFa

- c a l cu l a t ed y i e l d s .

10

u 6

CD

2 h

to 2 4

DOSE RATE (eV g" ' s'1)Figure 3 .2 . !. .4 .

Cal eu Lai ci Viol du o r 0, and N03 i r, the F.ïdiolysis ofat 700 l'on a; a fonction of Dose P.ite.

IO

3

PR-CMu-1 ]

(d) F e b e t r o n

The e i g h t h t u b e (545-042) has now d e l i v e r e d 1350p u l s e s . One module f a i l e d d u r i n g t h i s p e r i o d . Thenumber of p u l s e s used was 1128 g i v i n g a g r a n d t o t a l of9448 p u l s e s . T h i s i s a s u b s t a n t i a l i n c r e a s e in thenumber of p u l s e s ove r t h e l a s t p e r i o d and i s p a r t l y duet o use of t h e F e b e t r o n by t h e Appl ied P h y s i c s D i v i s i o n .T h i s may be r e f l e c t e d in a s e r i e s of manor f a u l t s whichr e s u l t e d in o v e r one week of down t i m e .

3 . 2 . 2 P u l s e R a d i o l y s i s of L iqu id Systems

a ) Pu l se Rad ip lys1 î s of N i t r i c Oxide in Aqueous Solut ion .

A n a l y s i s of t h e d;\ta r e p o r t e d p r e v i o u s l y (W.A. SeddonPR-CMa-10, AECL-3477) i s c o n s i s t e n t w i t h t h e fo rmat ionand decay of a new t r a n s i e n t s p e c i e s , (Nr 0-c ) .

The r a t e of decay of e aq was found t o be oscudof i r s t o r d e r and t h e h a l f l i f e , t^ , i n v e r s e l y p r o p o r t i o n a lt o t h e NO c o n c e n t r a t i o n from which we d e r i v e k ( e aq + NO)= 2 . 3 ± 0.4 x 10 ' M~'s~*. T h i s v a l u e i s lower than ane a r l i e r r e p o r t e d f i g u r e , (1) of 3 .1 ± 0.2 x 101 N T ' s " 1 ,b u t i s in good agreement w i t h t h e r e l a t i v e r a t e c o n s t a n tr a t i o s ( 2 - 4 ) ; k ( e ~ a q + NU)/k(e~aq + Ny 0 ) = 2 . 5 ± 0 . 2 ,k ( e ~ a q + N 0 ) / k ( e ~ a q + NO-, ~ ) = 5.4 ± 0 . 7 , and thi.' a b s o l u t er a t e c o n s t a n t s ( 1 , 5 ) , k ( e ~ a q + Nfc0) = 8.7 ± 0 .6 x 10and k ( e " a q + NO . ~ ) = 4 . 1 ± 0 .6 x 10 ' M~"s~* , r e s p e c t i v e l y ,

The g rowth of t h e t r a n s i e n t a b s o r p t i o n (moni toreda t 380 nm) o c c u r s w i th two d i s t i n c t r a t e s . i n i t i a l l yt h e r e i s a r a p i d pseudo f u s t o r d e r i n c r e a s e , t h e LM'.L-

of which i s a b o u t seven t i m e s s l ower than t h e r a l e otdecay of e~aq o b s e r v e d ir. t h e same s o l u t i o n . Thisi n d i c a t e s t h a t N0~, p resumably produced in r1 1 , does nota b s o r b s t r o n g l y a t t h i s w a v e l e n g t h bu t i s t h e o n w i r s o rof t h e i n i t i a l a b s o r b i n g s p e c i e s . We s u g g e s t t h a i t h i ss p e c i e s i s t h e r a d i c a l a n i o n ( N-0 ; )~ formed in a s ubsrqiu'iis l o w e r r e a c t i o n 2 1 .

e~aq + NO -* N0~ ' I '

N0~ + NO -* (N? 0? ) 2

- 66 -

PR-CMa-11

ï t was found that t. for the formation of (N^Og) wasinversely proportional to NO concentration and thatk3 = 3.3 -t 0.7 x 10 9 M ^ s " 1 .

F'ollowing the initial rapid build up of absorptiona slow additional increase is observed. The rate ofthis increase is a function of NO concentration but iscomplicated by its subsequent decay which is first orderar.d markedly pH dependent. Additional ( N s 0 a ) ~ might beformed via the initial formation of HNO and subsequentpH dependent dissociative equilibria. Pro]iminarycomputer calculations (in collaboration with J.W.Fletcher)are consistent with the sequence of reactions,

H + NO — HNO r3 "•

HNO + NO — HNB 0E : 4 1

HNa 0s ^ H r + Na 0a "

r 5 "!

HNa oa + NO - » H N 3 O 3 re i

HN3O3 -• HN0a + N£0 \l 1

A complete kinetic analysis as a function of NOconcentration. pH and ionic strength is required toelucidate the mechanism in any further detail. This workawaits the installation of a pulsed 2.5 MeV Van de Graaffaccelerator early in 197 0.

References

1. S. Gordon, E.J. Hart, M.S. Matheson, J. Rabani andJ.K. Thomas, Disc.Farad Soc, 36_, 193 (1963).

2. W.A. Seddon and H.C. Sutton, Trans.Farad Soc. 59,2323 (1963).

3. T.W. Woodward and H.C. Sutton, Trans.Farad Soc. 62_,70 (1966).

4. R.j. Knight and H.C. Sutton, Trans.Farad Soc. 6_3_, 1(1967) .

5. See M. Anbar and P. Neta, Int. J. of Appl.Radiât ionand isotopes, 18_, 493 (1967). '

- ( ) I -

!M'-CM.:- ] I

b) Pulse R a d i o l y s i s of EthanolJ.W. F l e t c h e r and W.A. Seddon

This work i s a c o n t i n u a t i o n of that p re sen ted int h e previous p r o g r e s s r epor t (p .6 ] PR-CMa-10, AECL-3477).

K ine t i c s of t h e a - e t h a n o l r a d i c a l CH.. Cï'OH, andr a d i c a l anion (CH3CH0) , have been s t u d i e d . Thea b s o r p t i o n spectrum of CH3CHOH i s s i m i l a r to t h a t observedin aqueous s o l u t i o n s of ethanoJ ( 1 ) , with a r e l a t i v e l yc o n s t a n t e x t i n c t i o n c o e f f i c i e r ' , below 280 nm. TheCH3CHOH r a d i c a l was s tud ied a t a wavelength of 255 nm and(CH_.CH0)~ at 350 nm where t h e CH3CH0H r a d i c a l absorbs onlys l i g h t l y .

There i s a r a p i d e q u i l i b r i u m I 1 between the r ad i ca land r a d i c a l anion m aqueous s o l u t i o n s of e thano l (1)however e q u i l i b r i u m r l l was not observed in pure e t h a n o l .

CH3CHOH + C H 3 C H B 0 ~ ~ CH 3 CH0~ + CH:, CH;. OH I 1

T h e CH3CHOH r a d i c a l r e a c t s v e r y r a p i d l y W i t h Oil i n a q u e o u s

s o l u t i o n ( 1 ) ( e s t i m a t e d k •• 1 0 ' M ' s ~ ' \ , h o w e v e r t h e r a t e of

r e a c t i o n w i t h CH.» CHa 0 i n e t h a n o i i s s l o w ( k i 1 0 ' M ~ ' B ~ ) .

T h e b a c k r e a c t i o n i s a l s o m u c h s l o w e r t h a n i n a q u e o u s

s o l u t i o n s o f e t h a n o J w i t h t h e e s t i m a t e d r a t e c o n s t a n t i'oi

w a t e r beir.Cj 1 0 B M ~ ' s ~ ( 1 ) a s c o m p a r e d t o k - : - 2 0 M ~ ' s ~ MI

e t h a n o l . H o w e v e r , t h e r e a r c i n d i c a t i o n s t h a t t h e r e a c t i o n

o f CH.-=CH20 w i t h . h e o t h o x y r a d i c a l 2 \ i s m u c h f . i s l o r t h a n

r e a c t 1 on 1 '' .

CHjCH^O + C H a C H £ 0 ~ — CH.-. CH0 + CH,-, CH; OH J "

T h e CH3CHOH r a d i c a l d e c a y s b y b i m o i e c u l a r k i n d i .-s

w i t h a r a t e c o n s t a n t 2 k - ( 1 . 6 i 0 . 4 x 10' . •, c, a M"" ' . s " ' l

w h i c h i s c o n s i s t e n t w i t h ' T a u b ' s v a l u e (2 ) a t 2 y 7 nm. i tC 2 5 5 ^ 2'CS9-,. T h e e x t i n c t i o n c o e f f i c i e n t i s l e s s a t

2 9 7 n m . t h a n a t 2 5 5 nm. b u t t h e e x a c t a m o u n t h a s no t b o o n

d e t e r m i n e d .

R e f e r e n c e s

1 . K . D . A s m u s e t a l . B e r . B u n s e n q e s P h y s C h u m . 7 0 , 7r>(.

( 1 9 6 6 ) „

2 . I . A . T a u b a n d L..M. D o r f m a n , J . A m o r . C h e m S u e n±. 4d r - !

( 1 9 6 2 ) .

- 68 -

PR-CMa-1

••- • 3 Electronics for Pulse Radiolysis

A pulsing circuit has been built for a 1600 wattXe arc lamp to be used for pulse radiolysis studiesA simple half-wave rectification circuit charges a .05farad capacitor to 60 volts. The capacitor is dischargedthrough the arc lamp using an SCR with high di/dtcharacteristics. A. secondary pulsing circuit shuts offthe light pulse soon after it peaks. This technique notonly reduces damage to the lamp electrodes , but alsoincreases the reproducibility of the peak light lev^l.The resultant pulse has a rise time of a few microseconds ,a peak gain of 40 over the quiescent lamp intensity andis flat for 200 microseconds. An AECL report to bepublished describes the circuitry further.

3.3 ISOTOPE CHEMISTRY

3.3.1 Optical Spectrum of Amine SolutionsJ.P. Butler See CRNL-160-7 Section 3.5.5.

3.4 REPORTS, PUBLICATIONS AND LECTURES

3. 4. 1 Observation of a large dose rate effect on the ozone yield inthe radiolysis of gaseous oxygen- A. W. Boyd, C. Willis, R. Cyr and D. A. Armstrong,Can. J. Chem. _47, 4175 (1969).

Pulse Radiolysis of Nitrin Oxide in Aqueous Solution,- W.A. Seddon and M. J. Young, Can. J. Chem. 48, 393(1970),

Pulse Radiolysis of Ethanol.- J. W. Fletcher, P. J. Richards and W.A. Seddon,In press, Can, J. Chem.

Radiolysis of Cyclohexane with Perflaorocyclohexane at VeryHigh Dose Rates.- N.H. Sagert, In press, Can. J. Chem,

^ '->••» - PR-CMa-11

4. REFORT OF MATERIALS SCIENCE BRANCH

by

B. Cox

PAGE

4.1 STAFF 70

4.2 SURFACE CHEMISTRY 71

4.2.1 Stress-Corrosion of Zirconium Alloys 7]4.2.2 Electronic Control of Metal Oxidation 754.2.3 Switching and Memory Effects in Zirconia 76

Films4.2.4 Transmission Electron Diffraction . 774.2.5 Stereograptuc Projections 784.2.6 Oxidation of Zirconium in Fused Salt at 300°C 784.2.7 Scanning Electron Microscopy; Crystallographic 81

Aspects4.2.8 The Movement of ^-^Ta Tracers During the 82

Anodic Oxidation of Tantalum4.2.9 The Movement of IBlfîf Tracers During the 82

Anodic Oxidation of Tantalum4.2.10 Anodic Oxidation of Metals in Partially 84

Aqueous Electrolytes4.2.11 Least Squares Fitting Frograms 85

4.3 CERAMIC STUDIES 86

4.3.1 Colour Centres and Lattice Defects in ThO2 8b4.3.2 Equilibrium Annealing of Thoria hb4.3.3 Diffusion of Thorium in ThO2 H84.3.4 Diffusion of Thorium in MgO 884.3.5 Diffusion of Sodium in NaCl _ s<

4.4 METAL PHYSICS 'J0

4.4.1 Precipitation Hardening of Zirconium Alloys qn4.4.2 The Annealing of Irradiation Damage in "1

Zirconium Alloys4*4.3 Diffusion in a-Zr 'J14.4.4 Diffusion in Al "1

4.5 REPORTS, PUBLICATIONS AND LECTURES ''2

4.4.4.

5.5.5.

123

ReportsPublicat-i on sLectures

- 70 - PR-CMa-11

MATERIALS SCIENCE BRANCH

4.1 STAFF

Head

Secretary

B. Cox

Miss M. Millar

SURFACE CHEMISTRY

3. CoxR.A. PlocN. Ramasubr amanianJ. P.S, PringleE.M. Schulson (1)A.J. Stirling (PDF) (2)

H. J.A.B.

ArnalCampbell

D. PhillipsS.B.T.P.M. G.

ThomasTrottierWatling

(RT)(Tg)(RT)(LA)(Tg)(Tg)

CERAMIC STUDIES

B. G. ChiIdsA. D. KingP. J. Harvey

J.B. Hallett (Tg)J. Moerman (Tg)

METAL PHYSICS

G.J.C. CarpenterG.M. Hood

R. J.J. F.

SchultzWattors

(Tg)'Tg)

(1) Joined Branch October 6, 1969(2) Joined Branch November 5, 1959

(Tg) Technologist(RT) Research Technician(LA) Laboratory Attendant

(PDF) N.R.C. Post Doctoral Fellow

' 1 ~ PR-CMa-11

4. 2 SURFACE CHEMISTRY

4-2.1 Stress-Corrosion of Zirconium Alloys- B. Cox

Stress-corrosion by iodine vapour at elevated tempera-tures has be-en suggested as a possible mode of fuel failure inzirconium alloy clad reactor fuel (H.S. Rosenbaum, Electrochem.Tech., 1966, 4_, 153). Little other work on stress-cracking ofzirconium m halogenated environments has been reported, al-though cracking has been produced in methanol/HCl solutions andin other impure methanclic environments (K. Mori, A. Takamuraand T. Shimose, Corrosion, 1966, 2_2, 29).

By contrast, extensive studies have been performed ofthe stress-cracking of titanium and titanium alloys* in "non-acueous'1 environments containing halogens, halogen acids andhalide salts. Titanium is found to crack readily in methanolicsolutions of these component.;, either with or without smallamounts of added water* An halogen vapours at elevated tempera-tures; and in other non-aqueous solvents (e.g. N2O4, Fréons,CHCI3) containing traces of halogen Cracking of commerciallypure titanium, and low alloys, in these systems appears to beuniversally ir.tergran.iiar, and to be largely inhibited by wateradditions greater than about one percent. Some work is now inprogress on the stress cracking of zirconium alloys in methano-lic solutions to ascertain the closeness of the analogy betweenthe behaviour of zirconium and titanium, and to study the fracto-graphy of the cracks produced.

Specimens cf crystal-bar zirconium, Zircaloy-2, Zr-2.5wt% Nb and Zr-2- 5 wt°/ Kb - C 5 wt% Cu alloys have been exposedin the pickled cond.tion, 1rs the form of unstressed coupons,partially restrained . w,th zirconium or Zircaloy-2 wire) U-bends,and tubing (Zircaloy-2 to methanclic solutions containingiodine or hydrorhicr.c acid i-.ogether with small amounts ofwater). The Zircalcy-2 tJbmg contained cold-work in the range0-42%. The solutions used and the cracking times of the variousspecimens are listed in Table 4 2.1 1. In addition specimens

See "Proceedings ci '.he Conference on the Fundamental Aspectsof Stress Corrcs.cr Cracking", C ' ? J .urn b u :-•., l'K7, tor recentpapers and b: bl . ogr aph ,••

- 72 - PR-CMa-11

have been exposed to commercial methanol, containing 1-2% H2O,and "anhydrous" methanol («3.1% H2O). All solutions based on"anhydrous" methanol have been contained in desiccators through-out the experiments.

In the methanol/iodine solutions cracking was univer-sally intergranular. The time for complete intergranular em-brittlement of unstressed specimens was generally less thanten times longer than that for cracking of che U-bends, andtimes for both cracking and embrittlement increased with de-creasing iodine concentrations. Cracking times for the Zircaloy-2 tubing tended to increase with increasing cold work. crackingand embrittlement of the Zr-2.5 Nb alloy and the Zr-Nb-Cu alloywas much slower than that of zirconium or Zircaloy-2, and thiswas reflected in the lower rate of weight loss in methanol/iodine for these specimens than for Zircaloy-2. The crackingtime did not appear to be greatly affected by water contents ofup to 2% in the methanol/iodine solution.

In methanol/HCl solutions the initiation step appearsto be intergranular in all instances. However, the subsequentpi ogress appears to depend on the stress level in the specimen.Thus, for unstressed specimens, and tubes with little residualstress and no external applied stress, the overall fracture ispredominantly intergranular. For the Zircaloy-2 U-bends andthe wires used to restrain the U-bends the propagation wasmainly transgranular. Cracking of the Zr-Nb and Zr-Nb-Cu alloysin this instance was mainly intergranular. Cracking in methanolHC1 solutions was very dependent upon water content. Unstressedspecimens were not completely embrittled in methanol/HCl; smalllocalized cracks were formed together with (in some instances)small regions of penetration which had the appearance of blis-ters on the surface.

Only one specimen has cracked so far (6 25 hr) in the com-mercially pure methanol (containing water). The first specimenfailed in the "anhydrous" methanol at 200-240 hrs.

Sections of specimens have been examined metallographi-cally to determine the relative amounts of intergranular andtransgranular cracking. Fracture surfaces have been studied onthe Scanning Electron Microscope, and typical micrographs areshown ir Figure 4.2.1.1.

STRESS CORROSION OF ZIRCONIUM ALLOYS IN METHANOLIC SOLUTIONS

SPECIMEN

Material

Zirconium

Zircaloy-2

Zr-2j Nb

AN

Zr-2fr Nb-i Cu

AM

Form

wire

wire

annealed sheet

••

tube-annealed20% CW42% CW

880°C Q/24 hr 500°C

anneal(sheet)

860°C Q/6 hr 53O°C

anneal(sheet)

StressMethod

tensile

tensileunstressed

unstressed

U-bend

no exter-nal stress

unstressed

U-bend

ur.s tressed

U-bend

MeOH

< 1 6 » ,

2 .25,2 .3(1)

21-96(E)

3.75,5(1)

6(I)72(E)

23(1)141(E)

410(E)

245,405(1)

410(E)

405(1)

TIME TO CRACKMeOH

0.1% I 2

~120<E)

32,16(1)

-

-

-

-

MeOH0.01% I 2

234 (E)

21.260(1)

;

-

-

-

-

• IN VARIOUS SOLUTIONS (HRS)HeOH

0.001% I 2

N.B.(>1000)

23,95(1)

-

-

-

-

0. 5% HCl/3% H20

>1000 ?

- 5 0 0 ( 1 )

-500(IB^

<21(T)

_

-

-

-

-

0. 3% HCl/0.6% HO

<iem +

308(IB)

<18(T)

78(I+T)185(I+T)360(I?)+T

>600(I)

<89,132(1)

>600(rB)

•-89 (IB)

Table 4.2.1.1

Cracking i s determined as the f i r s t v is ib le cracks at 10X magnification. Letters after the timeto cracking indicate i t s nature:-

tranagranular(T), Intergranular(I) , completeembrittleroent (E), not e, ±>r i t t led (N. E. I, local-ized cracking and "blistering"IB) .

Only uhe zirconium wires res t ra ining Zr~2$ Nb and Zr-2j Nb-j Cu specimens broke.

S.B. - Times to complete fracture are not shown. For specimens in MeOH/1% '7 this occurred at• 2X the time t j crackinq. lr. lower concentration MeOH/12 solutions this factor int-retis" ienormously because crack direction rotated from transverse (to bend) to lonyitadina1 va thdecreasing îorjine concentration R'J th.it crocks did nof_ intersect .

- 74 - PR-CMa-1

(b)

(c) (d)

Figure 4.2.1.1 Intergranular and transgranular stress-corrosionfractures in Zircaloy-2, X3000

(a,b) annealed Zircaloy-2, U-bends(c,d) 42% CW tubing(a,c) intergranular fractures in MeOH/l2(b,d) transgranular fractures in MeOH/HCl

NOTE: Some ductile tearing along grain edges is evident in (c).

Electronic Ccntr ci of Metal Ox i d a 11 or.- B. Cox

Further studies of the potentials across oxide films onmetals oxidizing in a fused nitrate-nitrite salt bath have shownthat both aluminum :oxidizir.g at 350°C) and uranium (oxidizingat 2Q0°C) show high negative potentials on the metal. For alu-minum the peak voltage, reached within the first few minutesoxidation, was _ 0 . 7 V unetal negative) a steady decrease to _0.3V (metal negative) occurred over about 5 hours. Uranium .showutian initial potential greater than -1 V which decreased to a mon.'or less steady value of -0.50 to -0-55 V. The potential per-sisted at about this value until virtually complete oxidationof the specimen caused it to break-up,

A comparison cf the potential-time curves of anodizedniobium and tantalum specimens with those of pickled specimensoxidizing in fused salt at 35OCC has shown that the potentialsacross the anodic f.lms rose slowly over a period of about 1 hruntil they exceeded the potentials shown by the pickled speci-mens .FR-CMa-iO). For tantalum the potential of the anodizedspecimen continued to be about 0 15 V more negative than thatof the pickled specimen, whereas for niobium the two potentialswere generally within 0 05 V of each other with the curves inter-secting several times This experiment suggests that anodicoxide films on tantalum restrict the electron current betterthan thermaiiy fcrmed oxide films- Thus, the inhibit:en of thethermal oxidation of tantalum by ;.od:c oxide films observedi r. these exper m e - t s , and previously reported by Fawel \J-Electrochem. Soc , 19f'-, 113. 1204 and i T , U±. 1222) mas-result from the increased electronic resistance cf the overallelectron; r process, rathe:' than any effect en oxygen diffusionrates Lccal electrical breakdown after a certain exposuretime would then lead to locai oxidation of the type observedboth here and by Fawel

The small difference between the p-.t er.t i ai - time curvesfor anodized and pickled ricbi irr, specimens sugqor, ts that rlicanodic film in th\s instance was less effective in restrictingthe electronic rprer.t than was a' arodic TapOc, film. Thus,less inhibition if the oxidatio", by fhe anodic film would bvexoected for niobium than for tantalum This was found to bethe case, although the; e was ne^ei ' v-olcss a s iqr. i f , can * rr iuc/t l *.r.in the oxidation rare -f +he ni^b.um spoc;mcr,

PR-CMa-11

2.3 Switching and Memory Effects in Zirconia Films- N. Ramasubramanian

The DC conductivity measurements (PR-CMa-10) are beingcontinued on anodic oxide films grown on Zircaloy-2 specimens.Experiments on films 500 to 2250À thick carrying evaporatedcontacts of gold and silver and painted contacts of silver(silver paint supplied by GC Electronics and Eccobond epoxysolder supplied by Emerson and Cuming) have shown a wide vari-ation in conductivity. All the films (four different thicknesseson a dozen specimens) tested showed a high resistance (>10l4n)to start with and one or more of the following characteristics -i) switching without memory ("astable behaviour"), ii) switchingwith memory ("bistable behaviour"), iii) light emission at sel-ected spots and iv) switching to a shorted state. On a singlespecimen the characteristics i), ii) and either iii) or iv)could be observed with the same type of contact at differentlocations on the surface. If in a particular experiment astableor bistable switching behaviour was not observed then withevaporated contacts light emission iii) and with painted contactsshorting iv) occurred.

The behaviour could be predicted from the voltages in-volved. An astable or bistable switching phenomenon was observedin the range of 3 to 6 volts irrespective of the oxide filmthickness whereas light emission or shorting were observed athigher voltages, above ~60% of the forming voltage.

The following characteristics have been observed con-cerning the light emission process: a) the number of spots showsa gradual increase with voltage until about 90% of the formingvoltage is reached; above 90% light emitting spots decreaserapidly in number; b) different groups of sites are active duringanodic and cathodic polarization. Following polarization up tothe forming voltage in one direction similar light emission spotsare observed during polarization in the other direction; c) insitu experiments using the optical microscope show that an indi-vidual spot only emits light once. The process is a chain re-action, additional spots becomirj active surrounding the initialone; d) SEM and optical micrographs suggest that at the lightemission spots the counter electrode material and oxide havebeen evaporated off; and e) oscilloscope traces show a rise timeof ^5x10-7 sec and a decay time of ~.3xl0~5 s e c for the currentflow during light emission. Averaging the current over theaffected area the maximum current density is ~2.5 amp/cm2.

FR-CK^-l1

When an astable or bistable switching is observe.: theswitching time .s less thar 10~ 8 sec. The processes at thethreshold vcltage that, lead to switching occur over a period ofa mil lisect-nd. The oscilloscope traces show a gradual currentrise over -_ 3xlO~ 4 sec followed by a slower decay prior to switch-l ng

The nature of these results indicates that the :;.etnllicbridge theory proposed by Chapman (R. Chapmnn, ElectronicsLetters, ^, 24'-. l^f-9) to explain switching phenomena can beelîmirated. The process is a solid state one involving twosteps: 11 1 on.c transport at the selected sites (injection frorrt-he electrodes; rea: 1 angement or electrolysis at the interfaces'!,and 2) switrhirg, the transport of electrons by tunneling (PR-CMa-10): no tempérât aie dependence of the conductivity is foun.iin the "on" state.

Transmission Electron Diffraction- R,A. Ploc

A series of equations has been derived to treat trans-mission electron diffraction mathematically. The variables in-volved are \, the wavelength of the electrons; L, the cameralength, the orientation and length of the reciprocal latticespikes and the direction of the incident beam. The procedureis being put into the CDC 6600 computer and has produced somefirst results Given an initial orientation the computer calcu-lates and plots the theoretical pattern which can be comparedto the experimental counterpart for confirmation- A subroutinehas been added to calculate the effect of tilting of the materialabout any direction lying .r. the plane perpendicular to the elec-tron beam- The procedure, therefore, treats, three dimensionalsectioning of the reciprocal lattices thereby insuring correctelectron diffraction interpretations- The procedure also de-termines exactly such things as twin planes, epitaxy piar.es, tvvnand double diffraction reflections, the separation of multiplediffraction patterns and the establishing cf crystal structures.

The computer output is plotted, the area involved hem-:

directly related to XL Reflections in both the rotate : an;1,unrotated cases are labelled wi *-h their Miller indices ss wo 1 1as being assigned their dev.atior.s from the exact- Brn.j.j c.*n : 1 • 1 - :•(in a separate output).

- 73 - PR-CMa-11

4 . - . "> Stereographic Pro nee Lions- R.A. Ploc

A stereographic projection for monoclinic ZrC>2 has beencalculated and plotted for a standard unit cell definition andorientation (see Figure 4.2.5.1). The need has arisen, however,for a complementary stereographic projection of crystal direc-tions based on the orientation of the crystal used for determin-ing pole positions. For this reason a series of equations hasbeen derived to allow a computer output of both these quantitiesfor any crystal system given two standard (in the cardinal posi-tions of the stereogram) poles and/or directions or any threepoles and/or directions which are not located at standard posi-tions. The equations have yet to be translated into a computerprogramme.

With the possibility of obtaining a 30" plotter for theCDC 6600 computer an effort is to be made to translate the aboveprogramme's output directly into the form of a stereographicprojection. We will then have a quick and convenient method ofobtaining projections for any material and for any orientation.

4.2.6 Oxidation of Zirconium in Fused Salt at 300°C- R.A. Ploc

Oxides were grown on zirconium at 300°C in fused saltfor two days and then subjected to polarization studies (standardtest geometry and protection as reported in PR-CMa-9, section4.2.7). Three experimentally identical samples were tested.One was used for a series of I-V measurements as a function ofdecreasing temperature; the second, was used as a control forchecking the effect of polarization and thermal changes and thethird was for checking the effect of temperature changes. Theexperimental data were plotted according to the assumption thatthe anodic and ionic currents were exponentially related to theimpressed specimen voltage. The cathodic current was assumed tobe the experimentally observed quantity less the ionic contri-bution. Delays between polarization cycles were approximatelyone-half hour during which time the new bath temperature wasattained and stabilized.

Figures 4,2.6,1a, b, c and d illustrate that the anodicand cathodic electronic currents displayed a non-random behaviourwhile the ionic portions caused concern about the validity of

l'U -(.Ma- 1 1

hkl

• - • . ' • . . • » w:

- . •><' j « - - . ^ . ' • J B B t ^ r ^ ^ - ' c " • - • ^ • ' ^ ^ ' : - ' :-

. - ; " - - : - - : - - . • • • : • • : • • • • • : • • : • ' - . w i i o . • ' • . . •

hklhkl

MonodMc ZrO,0*5142 A ~b-»2«AC9-3I9A

b«to-17306 n

Figure 4.2.5.1 Stereoyraphic projection o£ the poles forvarious (hkl) fcr monoclinic ZrO_.

- 80 - PR-CMa-11

(a)

(c)

"T

I

(b)

(d)

Figure 4.2.6.1 Assuming an exponential relationship betweenanodic and ionic currents and impressed voltagea, b and c show the anodic electronic, ionic andcathodic electronic currents as a function oftemperature; d illustrates the effect of polari-zation and temperature.

PR-CMa-11

using the above procedure to determine the nature of the pro-cesses contributing to the observed current. The wavy natureof the curves in Figure 4.2.6.1c is due to inaccuracies in theability to read small currents.

In Figure 4.2.6.Id the P39-#3 and P38-#4 refer to thethird I-V measurement on P39 and the first on P38. The otherthree curves refer to the 8th I-V measurement on P39, the secondon P38 and the first on P36. Before determining these curvesthe specimen temperature was reduced to 150°C then returned to273°C. It would appear from these curves that reducing the tem-perature between polarization measurements increased the catho-dic current. Since the resultant increase in the cathodic cur-rent differed for specimens P39 and P38, the intermediate pol-arizations at constant temperature may also be affecting theoxide.

Because of the inaccurate measurements of the smallcathodic currents, no effort was made to determine whether thetemperature dependence was compatible with Schottky emission or notExperiments designed to accurately measure these currents arein progress.

4.2.7 Scanning Electron Microscopy; Crystallographic Aspects- E.M. Schulson

Orientation dependent contrast from crystalline material.s,observed in the scanning electron microscope (SEM) has been in-terpreted in terms of electron channelling effects, when the in-cident beam is close to the exact Bragg position for particularspecimen planes (see Schulson and van Essen, J. Sci. Inst., 196 9,Series 2, 2_, 247 and bibli^rnphy) . Although their origin isdifferent the patterns appear similar to the well known Kikuchipatterns and each line corresponds to a particular (hkl) Brnqgplane. The occurrence of electron channelling patterns in SEMimages offers a unique method for determining the orientation,structure, and possibly perfection of crystalline materials whileunder direct observation. Two rocking-beam techniques for gen-erating patterns from selected areas as small as lCHan in dian.'/U.-ron bulk specimens have been developed (see above reference andvan Essen, Schulson and Donaghay, Nature, 1969, in pi ess).

Electron channelling patterns reported in the litera-ture to date have been generated using either the "Stereoscan"SEM or the "Geoscan" microanalyzer. It was therefore ot SUIVH;interest, with a view to later applications, to determine

- 82 - '- ~ PR-CMa-11

whether or not patterns could be generated in a "JSM-II" SEM.

To-obtain a sufficiently high current, well-collimatedbeam to generate electron, channelling patterns, the first con-~denser iens ' (.lens' 1)" was reduced to a minimum setting, and thefinal condenser-lens (lens 2), was turned off. The beam was,scannecf tKiôugîv abolit ±2° at 2b kv by selecting ths minimummagnification'setting. CJjxder these conditions, patterns ofreasonable (juâlity were obtained from a fairly perfect, epi-taxially grown silicon single crystal. An improvement inpattern "visibility" was effected by removing the pole piecefi-oia lens 1. This operation increases the beam current forthe- same lens settings, thereby increasing the signal to noiseratio in the collecced signal and thus allowing the lower.contract channelling lines to be seen. The pattern contrastappeared greater when collecting the reflected primary elec-trons only. The angular resolution of the patterns is curren-

' , tly, "•ÏOT-* radians. Further improvements in pattern resolution"' "' are anticipated by reducing the beam divergence.

Patterns,have also been generated from zirconium singlecrystals. In this case, however, the angular resolution was

. - considerably le_ss than that for the silicon patterns, indicating,perhaps, the presence of a surface film or alternatively a lessperfect crystal* Attempts to generate patterns from thoriacrystals were not successful, due to crystal charging.

4.2.8 The Movement of _182Ta Tracers During theAnodic Oxidation of Tantalum- J. P.S. Pringle and R.E. Pawel*

Pawel_has also observed the atypical anodization reported" in PR-CMa-10, 4.2.8, and is now trying to discover the cause.

4.2.9 The Movement of l -Hf Tracers During the.Anodic Oxidation of Tantalum- J.P.S. Pringle

The.migration of.hafnium was studied using 5 keVions implanted.in approximately 900Â of anodic Ta2Os; thesamples were reanodized at 1 mA/cm2 and 25°C in various electro-lytes. Although the results have not yet been -analyzed on the

Oak" Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A.

" PR-CMa-11

computer, the following points emerge.

a) The range profiles for 5 and 40 keV 18;I-Hf were normal dis-tributions with modes of about 32 and 115Â respectively,and standard deviations of about 20 and 65À. These resultsare exactly as predicted from previous range measurements(PR-CM-44, 1,3,3), and show that the 181Hf behave normally.unlike 353 (PR-CMa-9. 1,3,5).

b) With 0.1 M H2SO4 as the electrolyte, the 181Hf s i o w i y dis-appeared from the sample during reanodization. Only halfremained at 1400À, a quarter at 1750Â and 2,5% at 2750Â,A second sample was anodized to 1400Â and sectioned; theconcentration profile of the remaining lSlfif w a s approxi-mately half a normal distribution with the mode shiftedto the surface. The standard deviation remained at about25A, Under these conditions, therefore, the 181nf migratesslowly out of the oxide and into the electrolyte.

c) On anodizing in 0« Ol^M butyric acid as the electrolyte,by contrast,; only; 3% of the: activity was lost in anodizingto ;2550l, Removal of three 11Â oxide layers successivelyreduced the activity to 23%, 2,5% and 0,3% of the originalamount; the .concentration profile is therefore much narrowert.hctn as originally implanted- A second sample was anodizedto 1400Â with no significant: loss of activity; on sectioning,half ^he activity was removed with the first 7JL of oxide,while the remainder was distributed in, much the same way asfor the specimen anodized to 1400À in 0,1 M H2SO4»

The migration of i8*Kf within the oxide is therefore thesame for both electrolytes, bur there is a marked differ-ence in behaviour at the oxide/electrclyte boundary. The ^1 8 1Hf migrates readily xnto the 0-1 M H2SO4 electrolytebut. net into 0-01 M butyric acid; i-f\ the Jatter case, it'piles up! against the oxide surface, -""•.•:'. • ;; : ."'^%.'-- "

d) To make sure that, the lBÏHfrhàd. not changed its form inpiling up against the oxide surf ace, a saispïë was anodized •'•.•;"::to 2550Â in 0,1 M bu~yrîc acid with 2% loss, and the anodi-zation was then continued in 0,1 M H2SO4. 'One quarter ofthe 18lHf was removed in the first 15Â of anodization inthe sulphuric acid and one half in the first 40Â, the.."ratethereafter decreasing- No change in properties was there-fore apparent in contrast to 35g (pR-CMa-9, 1,3.5). Thedifference in behaviour with the two electrolytes Is veryprobably related to differences in hafnium solubility. Un-fortunately, iittle information is available on the chemistryof hafnium, but it is expected to be similar to that of zir-

- 8 4 - PR-CMa-11

conium. zirconium salts of oxy-acids are extensivelyhydrolyzed in aqueous solution, with the precipitationof hydrated zirconium dioxide, but stable, soluble com-

- - - - - piexe's are formed in the presence of-excess strong acids,such-as HotzrO(304)2] 3 H2°- Ifc i s P*°P°sed. therefore,that the.lQlHf "can go into" 0.1 M, H2SO4 solution as theacid sulphate complex, but that since no similar complexis formed with butyric acid, solution does not occur. Totest this hypothesis, several other electrolytes weretried,

e) Zirconium forms complex a'ïid nitrates with nitric acid;the Hf18* behaved in 1 M UNO3 as in 0.1 M H2SO4. In 0.1 MHNO3 and 0.01 M H2SO4, however, the rate of

lfilHf loss wasmarkedly reduced, and some began to pile up against thesurface; dilution will obviously reduce the rate of com-plex formation. In 0.01 M acetic acid, 0.01 M KOH, and0.01 M KOH + 0.1 M K2SO4, where no complex formation isexpected, little or no loss of 1 8 1Hf was observed as in0.01 butyric acid; the sulphate complex is not stable inalkaline solution.

Hafnium therefore tends to migrate out of the Ta20j on"anodizing, but whether it crosses the oxide/electrolyteboundary depends on its solubility in the electrolyte.

4.2.10 Anodic Oxidation of Metals inPartially Aqueous Electrolytes- J. P.S. Pringlt and D. Phillips

The anodic oxidation of some metals such as molybdenumand vanadium is. difficult to study, because they do not anodizesatisfactorily in aqueous electrolytes. Following a privatecommunication from R. Kelly (McMaster university, Hamilton) twopartially aqueous systems have been tried. One, glacial aceticacid made 0»02 M in sodium tetraborate and 1 M in water., per-mitted molybdenum and vanadium to be anodized to 95 volts at2 mA/cm2-and 100 volts at 5 mA/cm2 respectively; reasonablyuniform interference colours were observed on both metals. Theother, ethyleneglycol saturated with ammonium pentaborate,permitted indium to be anodized to 97 volts at 5 mA/cm2; againreasonably uniform interference colours were observed. Molyb-danum and vanadium will not form interference films at all inaqueous electrolytes, while indium gives non-uniform colours.

- 85 -PR-CMa-11

lu 2.11 Least Squares Fitting Programs• - J.P.S. Pringle

Experimental data on the distribution ofimplanted"atomsin anodic Ta2C>5 have been analyzed by means of a least squaresfitting program written for the G-20 computer. The originalprogram, based on the computer library routine LSQ, wa-j foundto be inadequate, and so the program has subsequently been re-*vised several times (e.g. PR-CMa-6, 1.3.5). Re-examination ofthe latest "version showed, however, that it too was faulty. Athorough study of the whole problem vras therefore undertaken.

The object of the least squares fitting program is tofit the function

Y = F(X?C)

to the experimental X,Y points,- in such a w^y that the individualerrors in the measurements of X and Y are taken into account, andso that the following requirements are met:

i) The function F g .ves a satisfactory description of therelationship between X and Y.

ii) Best estimates for the parameters C are calculated,iii) Standard errors in these estimates are also calculated.

The original program provided no information on i), thecorrect answer to ii) and two answers to iii), though nobody seemedto know which of these was correct, incorporation of a x^-testprovided an estimate for the goodness-of-fit i), and by consider-ing the origin of the two standard errors, iii), the correcterror has been identified. A. J. Ferguson (Nuclear Physics Branch)has suggested a modification of the Newton-Raphson procedure usedin LSQ, which takes into account the errors in both X and Y.

Results using the final program are rather difficult tocheck, as the problem of making least squares fits when thereare errors in both components has scarcely been touched apart.from the special case of a straight line. However, fits madeusing th^ present program^ to a straight line example quoted inthe literature, do give the same answers as those reported, andthe results are invariant when X and Y are interchanged, as, ofcourse, they should be.

- 36 - PR-CMa-11

4.3 CERAMIC STUDIES

4.3.1 colour Centres and Lattice Defects in ThO2

- B.G. Childs and P. J. Harvey

As reported in PR-CMa-10, impurities seem to play amajor role in the band structure of .the optical absorptionspectra of unirradiated and irradiated thoria. This conclusionis based on the variability of the band areas for specimenssubjected to a given treatment and on the variation of colourintensity within a given irradiated specimen. This variabilityparallels the reported variation in the impurity concentrationfor our specimen material an*3 is not unexpected in view of theextremely high temperatures and thermal gradients involved inthe arc-fusion process.

The mean density of centres, N, within the region ofthe specimen scanned by the spectrophotometer beam can, in -principal, be calculated directly from the band area usingSmakula's expression

Nf = * § S a W (1)2e2 (n2 + 2 )

2 m a X

in this, f, is the oscillator strength—a parameter related tothe probability of the particular optical transition concerned— N , is the refractive index at the wavelength of the band andm, c and e have their normal meanings, ot^x W, the productof the absorption coefficient at the band maximum and the halfwidth of the band, is ralated to the band area A (for Gaussianbands) by

a W = 0.94 A , (2).max

Substituting in equation (1) we obtain

Nf = 3.48 x 10 1 4 A (3)

No f values are available for the ThO2 centres at present. How-ever, for other materials and centres, values ranging between0.01 and 1.0 are normal. If we assume to an order of magnitudethat f = 0.1 the maximum band areas for the specimens studiedare as follows:

" 87 " PR-CMa-11

Band (eV) 1.49 1.67 1.80 2.03 2.32 2.80 3.03 3.62 4.03 4.52

1 2 2 4 2 8 I'M'"-210 10 4 6 102 15

These values are in the same range as the impurity concentra-tions determined by analysis.

in an attempt to relate individual impurities with oneor more of the characteristic bands a new experimental proce-dure has been adopted. Thin single crystal specimens (less than25 microns thick) have been subjected successively to the fol-lowing treatments:

a) 2 hr anneal in argon at 1400°C in Ta element furnace (verylow oxygen partial pressure);

b) gamma irradiation of 106 R;c) 2 hr anneal in air at 1400°C;d) ion implantation using the Mass Separator;e) 2 hr anneal in air at 1400°C;f) 2 hr;anneal in argon at 1400°C in Ta element furnace;g) gamma irradiation of 10$ R;h) 2 hr anneal in air at 1400°C. -

After e ach tr e à tmen t the _optical absorption spec tr a were me a sur ed.In treatment d) the specimens were bombarded with 40-60 keV ionsfor sufficient time to produce a theoretical implanted impurityconcentration at least a factor of 2 greater than the highest de-termined analytically. A large amount of radiation damage isproduced by the heavy particles and the specimens are greatlydarkened immediately after bombardment. Treatment e), however,is sufficient to remove the damage and the discolouration.

,. TO date, 8 specimens have received treatments a), b) andc) : one specimen has received a), b), c) and d).having beenbombarded with aluminum and one specimen has received all 8 treat-ments (the bombarding ions being in the N 2

+ formJ7

Initial observations on the band structure of the specimensubjected to N 2

+ bombardment reveal:

1): The band areas of thr; 2.80 eV, 4.03 eV and 4.52 eV bands allincrease between treatments d) and e). No such increase isfound in the absence of treatment d) (see section 4.3.2).

2) The relative magnitude of the increases is in the order '2.80> 4.03 > 4.52.

3) The 3.62 eV band is reduced in area between treatments a)and f ) . However, no change is observed in the area of the

- 86 - ," - ' PR-CMa-ll

3.03 eV band.

Previously it was reported that the 2.80, 4.03 and4.52 eV bands are probably hol.e centres. Furthermore, a relationship has been shown to exist between the-3.62-and .2. 80 eVbands particularly in the cas3 of the Cerac specimens.

4,3-2 Equilibrium Annealing of Thoria- B.G. Childs and P. J. Harvey

2 specimens have been subjected to various treat-ments to ensure that a two hour anneal atl400°C is sufficientto establish equilibrium. Specimens have been annealed at1400°C for two hours in argon and the absorption spectra mea-sured. Subsequent anneals of up to 24 hours at 1400°C havenot altered these spectra, comparative studies on air annealedsamples have led to similar findings. One can state, therefore,that a two hour anneal in either argon or air at 1400*C is suf-ficient to establish equilibrium at that temperature. -

Further proof was obtained during experiments in which. an attempt, was being.made to produce the 2.80, 3.03 and 3.62eV bands simultaneously. Crystals were annealed in argon at1400°C for 2 hrs. They were then given anneals in air at 600°Cand 650°c for 30 minutes. This latter anneal was sufficientto remove all traces of bands characteristic of reduced speci-mens. These experiments are being repeated at lower tempera-tures for shorter time intervals to obtain information aboutthe annealing kinetics of the defect entities involved in thesebands.

4.3.3 Diffusion of Thorium in ThOg and UO2- A. D. King

This work has been suspended for the present due toan inability to obtain Gaussian diffusion, profiles, and liencediffusion coefficients which were representative of true lat-tice diffusion. Future experiments will be prepared in thelight of information obtained from diffusion studies of othernon-metallic systems, in particular of more tractable lowermelting point ionic solids (see section 4.3.5).

4.3.4 Diffusion of Thorium in MgQ- A.D. King and J. Moerman

A further diffusion run at 1575°C* for 24 hrs was carriedout using less tracer; to minimize any solubility problem. As

- 89 -PR-CMa-11

^ -Xn '^è ^revx^s xun {see PR-CMa-10, 4.3.6) approximately 90%.;••. of the activity was located in the first 0,,4[m. Between ~1

and:~4pm the linear slope of log c va x 2 corresponded to adiffusion coefficient of 11.0 x 10~14 c m 2 / s e C f Wftich is again

" some three-orders of magnitude lower than the diffusion coef-ficient for Kg at this temperature determined by Lindner andParfitt (J, chem, Phys. .23, 182, 1957).

It is perhaps of interest that Lindner and Parfitt1sdata refer to air annealed samples. Some aspects of the elec-trical conductivity measurements obtained by Mittoff (J. chem.Phys. 3a, 1261, 1959 and J. Chem. Phys. 36_, 1383, 1962) couldbe explained if there were an excess OJL anion vacancies atlow oxygen partial pressures (<10~5 atmos.) and an excess ofcation vacancies at high oxygen pressures; although this re-sult strictly depends on the presence of impurities of vari-able valence. (it should be noted that the defect structureof MgO is by no means certain.)

} - The oxygen partial pressure in the present experiments...; :/•• was not measured/ but should be <10~5 atmos. and there is the

possibility that the cation vacancy concentration could there-fore have been reduced. This could contribute to a low thoriumdiffusion rate. Solute diffusion experiments on air annealedsamples1, preferably with a soluble solute may give informationon this point.

4.3,5 Diffusion of Sodium in NaCl' • ^ i J. Moerman

Single crystals of sodium chlorideof high purity U 5ppm totar'Iiflpurities) have been prepared fôç diffusion studieswith surfaces polished as in the Work on the refractory oxides.The tracer isotope il5hr,24jja) j.s prepared by neutron irradi-ations of spectroscopically pure NaCl. Active layers of NaCl,~ 0 . l(jjn thick, hâve been evaporated from a heated tungsten fila-ment onto two specimens and diffused for 1 hour at 685 and632°C respectively. The specimens were sectioned using theautomatic polishing machine as inthe previous diffusion stu-dies of oxides, and the isotope activities determined by y-counting. Section thicknesses have been determined from thetotal weight loss after a number of sections were removed. Theresulting log c vs x2-plots were linear over almost two ordersof magnitude In concentration, giving diffusion coefficientsof 1.3 x 10~ 9 ahd 1.0 x 10~9 cm2/sec respectively. The firstof these values is in excellent agreement with published databut the second Is rather high.

- 90 - PR-CMe-11

Both profiles showed a low activity tail at deeperpenetrations Which is ; thought to be a result of short .circuit-ing diffusion as a result of the deformation introduced duringsurface preparation. This.feature-is of. interest in view ofthe main purpose in this study of NaCl which is to,investigatenon-Gaussian diffusion profiles. To this end experiments atconsiderably lower temperatures with respect to the meltingpoint Cs0.6 Tm) are of more interest,- together with investi-gations of the effects of different surface preparation, evap-oration, and sectioning techniques.

Also of interest are diffusion experiments to simulatethose on the fluorite oxides, in which the cation is the slowlydiffusing species, and crystals of calcium fluoride have beenobtained for this purpose.

4.4 METAL PHYSICS

4.4.1 Precipitation Hardening of Zirconium Alloys

a) Microhardness Measurements- G. J.C Carpenter and R. Meacher

It was noted in the previous report (PR-CMa-10,4.4.2) that the microhardness measurements from heat treatedzirconium alloys showed considerable scatter, thought to bedue to oxygen pick-up near the surface. Further measure-ments were therefore made following grinding and polishingspecimens to a much greater depth below the surface. Thehardness values obtained after this treatment showed onlythe normal scatter, and were close to those obtained inother experiments where the same alloy/heat treatment com-binations could be compared. Before conclusions can bedrawn from this work some further measurements must bemade from some of the samples selected oh the basis of thepresent results and the observations using the electronmicroscope.

b) Electron Microscopy- G. J. C. Carpenter and J. F. Matters

Thin foils prepared from the above specimens havebeen examined in the electron microscope. Results relevantto high temperature alloy development are as follows:

" 91 " PR-CMa-11

i) The precipitation of the needles reported previously(PR-CMa-7, 3.2.3) in an a-homogenized Zr-2 wt% Alalloy can be influenced by a low temperature nucle-a fci on 'tr é.a tmen t.

ii) A high density of spheroidal precipitates can beintroduced into a Zr-2 wt% Al alloy by ageing at700°C following p-quenching, although the distribu-tion is rather irregular,

iii) Precipitates have also been observed in the p-. quenched and aged Zr-3 wt% Sn-1 wt% Mo alloy. Thescale and distribution of these precipitates wasa sensitive function of temperature.

4.4.2 The Annealing of Irradiation Damage in Zirconium Alloys- G. JVC. Carpenter and J.F. Watters

The unirradiated control specimens of the zirconiumalloys used in this experiment have been examined using theoptical and electron microscopes. The (3-quenched alloys allshowed the usual martensitic structures.

A second series of specimens had been annealed forlong periods at successively lower temperatures in the a-phasein order to approach the equilibrium structure. Most of thesespecimens contained coarse intermetallic precipitates; an ex-ception was the Zr-1% Al material in which most of the alumi-num had remained in solution.

4.4. 3 Diffusion in g-Zr- G.M. Hood and R. J. Schultz

Samples of single crystal a-Zr have been prepared forstudies of the anisotropy of self diffusion* Surfaces para-llel and perpendicular to the basal plane have been preparedto within a flatness of ±0.3 microns. The diffusion experi-ments are being withheld until a very high vacuum annealingfurnace, now ander construction, is completed,.

4.4.4 Diffusion in Al- G.M. Hood and R. J. Schultz

A survey of data on solute-vacancy binding energies(Ep) in Al shows in a number of instances, incompatability withmeasured activation energies (Q) for solute diffusion in Al,when, these Q values are assessed in terms of current theoriesof impurity diffusion, Recent N.M.R.measurements on dilute

- 92 - PR-CMa-11

alloys of Al may help to provide at least a partial answerto the problem. The situation is currently being investigated.

4.5 REPORTS,

4.5.1 Reports

* TRG 1870(C/X)

4.5.2 . publications

Electrochem. Soc.J. (submitted forpublication)

J. Amer. CeramicSoc. (submittedfor publication)

* Acta Met.(accepted forpublication)

* Phil. Mag.843 (1969)

* Nature(accepted forpublication)

Phil. Mag.(accepted forpublication)

PUBLICATIONS AND LECTURES

"An Investigation of the Nucleationand Growth of Gas Bubbled in Metalsand Their Effects on Mechanical Pro-perties Using Model Systems"-G.J.C. Carpenter and R.B. Nicholson

"Forming Voltage and Plasma Pertur-bation Effects in Plasma Anodization"- N. Ramasubramanian

"Colour Centers and Point Defects inIrradiated Thoria"- B. G. -Childs* P. J. Harvey andJ.B. Hallett

"The Equilibrium Vacancy Concentra-tion in an Aluminium Copper Alloy"- A.D. King and J. Burke

"Electron Channelling Patterns FromFerromagnetic Crystals in theScanning Electron Microscope"- D.C. 'Joy, E.M. Schulson, J. P..Jakubovics and C.G. van Essen

"Electron Channelling Patterns FromSmall (lOpm) Selected Areas in theScanning Electron, Microscope"- C.G. van Essen, E.M. Schulson andR.H. Donaghay !

"The Diffusion of Iron in Aluminum"- ;G.M. Hood

* research done prior to AECL appointment

4.5.3 Lectures

" 93 ' PR-CMa-11

Thomas Graham "Solute Diffusion in a-Zr"Memorial Symp., - G.M. HoodGlasgow, Scotland, (to be published in conferenceSeptember 1969 proceedings)

American Ceramic "Colour Centers and Point DefectsSoc., Basic Science in Irradiated Thoria"Conf. ..Ottawa, -E.G. Childs, P. J. Harvey anaSeptember 28-30, 1969 J.B. Hallett

PR-CMa-ll

5, Ti:i-Monthly Progress Report of McMaster University

5.1 ; Theoretical Studies of the Fission Process : -K. S. Thind and R. H. Tomlinson

Shell corrections to the liquid-drop deformations of 'nuclei as reported by Strutinski1 can be used to determinedeformation energies of fission fragments, if the fissioningnucleus is approximated by tvo tangent spheroids at scission,then minimisation of the sum of the deformation energy andcoulomb repulsion energy leads to a suitable explanation ofthe variation of kinetic energy and excitation energy of thefragments as a function of mass3. In this model the calcu-lated coulomb repulsion energy is much larger than the

; : j observed ki.netid energy. An introduction of a distance of: ;:separation D « 0.9 fermi in reference (2) reduces this

discrepancy/ but no physical basis for this choice was given.

:-:-''.:::.;"'-->;;-.-;' :pur;-preiiminary calculations on the same model indicatesthat a separation D ^ 3.0 fermi would be a more Treasonablevalue in view of the "skin-thicknesses" of nuclei observed inelectron scattering experiments. We obtain coulomb repulsionenergies which are lower than the laboratory kinetic energiesand will be able to show that part of the observed kinetic

> ; energy comes from the fragment kinetic energy at the instantof scission. Ihis is quite different from the statisticalmodel of Fpng3 who assumed that the kinetic energy at scission

;^W<S;P^ progress to account for theW^':Sr::i^|0^pt!i^ass'S;yi:eld1;distribut;ion on the basis of the assumptiontf*i^ charge split is

™ ^ e P ^ à e n ; ^ of kinetic "energy states.

:" '::r;^ 'Sf tïutihsik;i",:" V.M. Nucl. Phys . A122 ( 1968 ) , 1-33 .

yi^z^itmmin^F. and Districh, K. Nucl. Phys. A129 (1969). 241-258.

3 : Fong, Pi Phys. Rev, 102 (1956), 434.

PR-CMa-11

5.2 • Ternary Fission Studies - G. Kugler and W.B. Clarke

In our study of ternary fission yields of \]'i3€ wehave failed to detect any evidence for the formation of thestable and long-lived argon and neon isotopes. We are nowinvestigating the formation of helium in the fission process.

He4 emission in ternary fission has been studied byseveral groups1 and it has been found to occur about once in300 binary fissions. Other light nuclei, such as H1 , H2, H3,He6 , He6 , Li, Be, and heavier fragments have also beendetected and energy and angular distributions have beenmeasured for soma of these species2. The formation of He3

has not yet been confirmed.

In our investigation we hope to measure mass-spectro-metrically the absolute frequency of formation of helium infission, the ratio He3/He4 , and possibly ranges and energiesof He'" and He* with a stacked foil technique. All earliermeasurements on light fragment emission in fission have beendone with solid-state detectors and track studies. Our firstefforts at measuring the fission-produced He in Al catcherfoils have failed due to the ftl127 (n,a) Na"'4 reactioncontributing the major portion of the He which was seen. Wehope to overcome this problem by using different stoppingmaterials and (or) irradiating our samples of u j a B in athermal column.

References :

1 Latest review on the subject given by N. Feather at theSecond Symposium on .the Physics and Chemistry of Fission,Vienna (1959).

3 Raisbeck, G.M. and Thomas, T.D. (1968) Phys. Rev. 172.» P-1272.

- 96 - PR-CMa-11

6. REPORT OF UNIVERSITY OF OTTAWA

Due to Dr. Cohway's pending absence from the University of

Ottawa, while serving as Commonwealth Visiting Professor at the

Universities of Southampton and Newcastle, the research contract was

terminated in September.

- 97 -PR-CMa-11

7. REPORT OF THE UNIVERSITY OF WESTERN ONTARIO

1.1 Stresses Generated in Oxide Films on Zr-2.5 wt% Nb- C. Roy and J. Wu

The stresses generated during oxidation of Zr-2.5% Nbat 500°C are being studied using the bending method to obtaininformation on the effects of alloying additions and the me-chanical strength of the substrate. The specimens have beenfabricated from cold worked sheet stock (AW), annealed invacuum for 24 hours at 580° and furnace cooled. Table 7.1.1summarizes the results. Curves of the average stress in theoxide as a function of film thickness showed general featuresvery similar to those found for Zircaloy-2.

The X-ray diffraction patterns of the oxide show thatthe morphology of the oxide film on Zr-2.5% Nb is qualitativelysimilar to that on Zircaloy-2, i.e. tetragonal oxide appearsearly in the oxidation process and the crystallites reorien-tate towards a comrfion 1(32~ fiber axis with increasing thickness.

7. 2 X-ray Diffraction Analyses of the Oxide Films- C. Roy and G. David

a) Study of the Peak intensities Versus Film Thickness

A comparison of the experimental relative inten-sity l / I o to the theoretical relative intensity of indivi-dual reflections as a function of film thickness has pro-vided information on changes in the crystallographiccharacter of the oxide. Figure 7.2,1 shows two modes ofvariation shown by the monoclinic 102; and tetragonal 111peaks (respectively) for zirconium specimens oxidized at500°C. While the theoretical and experimental curvescoincide well, for the 102" peak, a distinct transition^occurs simultaneously for both the (111)T and the (202)M

(not shown) peaks at a film thickness of about 3pm.

Features of the X-ray patterns which suggest thatthe appearance of the (202:)M and ( l i l ) T peaks during oxi-dation results from oxide recrystallization at the inter-face due to the high localized stresses, are:

i) The magnitude of the (2C2)M peak displacement ismuch higher than that of any of the peaks presentearlier . The stress computed from this peak dis-placement indicates a stress of about 2.85 x 105

psi in the inner ,1.5(jm layer of an oxide film 4.8pm

TABLE 7.1.1

SUMMARY OF THE RESULTS OF STRESS MEASUREMENTS DURING OXIDATION OF Zr-2.5 wtji «fa SPECIMENS

Experi-mentNO.

A #1

A #2

A #3

A #4

A #5

A #6

B #7

B #8

B #9

B #10

;B #ii

B #12

B #13

StripThickness

(nun)

0

0

0

0

0.

0.

0.

0.

0.

0.

0.

0-

1.

.28

.24

. '56

,267

.267

30

90

918

907

914

91

906

98

Time ofOxidation(hours:mins)

1:00

4:00

5:00

3:00

2:00

23:00

34:00

10:00

15:00

20:00

45:00

29:00

80:15

WeightGain

(mg/dm^)

13

21

30

18.

15.

71.

112,

35.

60.

67.

-

93.

228.

.65

.0

.75

84

8

8

3

7

0

0

25

5

Total Move-ment Due toOxidation(Divisions)

622

2086

2817

1602

1499.

8251.

1618.

872.

729.

1040.

-

1526

4670

.5

.0

.0

.0

0

0

0

0

0

0

Average Stressin the Oxide

After OxidationX 105 psi

0.573

0.874

1.17

0.967

0.688

1.495

1.85

3.24*

1.77

2.01

-

2.1

1.2

Remarks

X~ray diffraction study(reflection)

X-ray diffraction study(reflection)

X-ray diffraction study(reflection)

* glass fibre moved veryrapidly in first 5 minsup to 130 divisions

X-ray diffraction study(reflection)

Al coated side oxidized

X-ray diffraction study(reflection and trans-mission) , anriealed700°C 42 hours

RE

LATI

VE

IN

TEN

SIT

Y

IS)

I

aN

I

50 •n

RE

LATI

VE

IN

TEN

SIT

Y

o>

—

§ 50 i n

" 101 " PR-CMa-11

thick,ii) The allotropie transformation ZrC>2 (mon.) = ZrC>2

(tet. ) has been reported to occur at .500oC undera hydrostatic pressure of ~3.3 x 10^ psi. The factthat the (20Z)M and (111)T peak develop simultan-eously suggests that their occurrence is inter-related.

iii) Secondary peaks, e.g. (113)M cease to develop withthe appearance of the new orientations. Further-more, the rapid development of the latter may in-dicate a decreasing proportion of amorphous oxideat the interface. A similar sequence of eventscharacterizes the growth of the oxide on Zircaloy-2,except that it occurs much earlier in the oxidationprocess.

b) Effect of Oxidation Temperatureon the Mode of Oxide Growth

The X-ray pattern of an oxide film 15(jm thickformed on jsirconium at 800°C showed high intensity, stress-free peaks (up to the limit of the X-ray penetration).The ratios

I. , , oxide filmhkl

Zhkl Zr°2

for oxide films formed at 500°C and 800°C show that theoxide formed at 800°C possesses the same texture but amuch higher degree of crystallite orientation than thoseformed at 50û°C, It should be pointed out that importantreflections occuring in these films, e.g. 117, 302" and 222are not reported on the ASTM card No. 13'. 307.

The degree of crystallinity of each oxide formedat 500°C and 800°C has been estimated. An inverse poleficjure shows that the orientation of the crystallites wassimilar for oxides formed at both temperatures- Thedensity of poles along an equatorial section (010 zoneaxis) can be plotted for oxides formed at the two tempera-tures (Figure 7.2., 2). Assuming that the distribution ofthe poles is identical along any section of the inversepole figure containing the fiber axit, it is then possibleto integrate the density of poles over half the inversesphere of poles. Thus:

302 101

- ! 02 -

FIG. 7.2.2

102 104 001

PR-CMa-11

102I

101

I ! I I60 90°

I120°

T i l r

LONG ITUDE

• ZIRC 2 500" C

O Zr 500° C

Zr 800" C

302 10! 104 001 102 101

- 103 -

PR-CMa-11

• 90o2v. J1 p sin eae = x

where P is the density of poles, 8 the angle between thepoles and the fiber axis, and X = 1 (or 100%) for random

Values of X computed for the oxide grown undervarious conditions were: X = 1 for zirconium oxidized at800°C; 0.66 for the oxide grown on zirconium at 500°C;and 0.58 for the oxide grown on Zircaloy-2 at 500°C. Manyfactors may affect these estimates, however, it wouldappear that the oxide films formed at 500°C contain a muchlarger proportion of "amorphous" oxide than those formedat 800°C.

TABLE 7.2, 1

RATIO OF INTENSITIES OF X-RAY REFLECTIONSFOR ZrO2 POWDER AND OXIDE FILMS "IN SITU"

Reflection<lftl)H

O i l1 1 0H Ti l l002200102021211102112207022220127221202013113*1303 1 Î307*213"311123104

ReticularDistance

d Â

3.6953.6343.1612.8402.6242.5382.4982.3322.2112.1932.0211.9891.8481.8171.8021.7811.6951.6581.6511.6421.6081.5381.4951.4771.4471.321

Density of PolesZircaloy-2

Oxidized at

0.050 . 00.4 *'0.001 . 8

-7 . 50.030 . 6

——3

.••.I-'- o0 . 0 .0 . 50 . 00 . 0

2 . 4: —

0 . 11 . 42 . 7

0• : • —

5

500°C Oxidized at

0 . 10 . 00.28

io.oi2 . 2

-9

0.07] 0.35(0.2• • • • • _ .

3 . 60 . 30 . 00.350 . 00 . 0

-2 . 2

-0 . 01 . 32 . 70 . 00 . 24 . 5

-'P)Zirconium

500°C Oxidized at 800°C

0.300 . 00.4.5,.0.02;1 . 9o.o :

150 . 00 . 40 . 00 . 0

120 . 50 . 00 . 60 . 00 . 0

-2 . 30 . 00 . 02 , 43Î70 . 00 . 55 . 5

- measurement unreliable

= Khkl) for the oxide layerI(hkl) for the powder

* not reported on the ASTM card No, 13.307

A d d i t i o n a l copies of îhts documentmay be ob ta ined f rom

Scient i f ic Document O isJr ibu i ian OHiceAtomic Energy of Canada Limited

Cliolk ttiver, On ta r i o , Canada

Prictf - S 2 0 C per copy

362-70