WAPD-TM-1320 DOE RESEARCH AND

DEVELOPMENT REPORT

LOW STRAIN DIAMETER EXPANSION OF INTERNALLY PRESSURIZED ZIRCALOY-4 TUBING AT HIGH TEMPERATURES (LWBR Development Program)

MARCH 1978

CONTRACT EY-76-C- 1 1-00 14

BETTIS ATOMIC POWER LABQRATORY WEST MIFFLIN, PENNSYLVANIA

Operated for the U. S. Department of Energy by

WESTINGHOUSE ELECTRIC CORPORATION

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

DISCLAIMER

Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

wAPD-TM-1320

Spec ia l Externa l D i s t r i b u t i o n

LOW STRALN DIAMETER EXPANSION OF INTERNALLY PRESSURIZED ZIRCALOY-4 TUBING AT HIGH TEMPERATURES

(LWBR Development ~ r o g r h )

L ; S. White and C . C . Busby

March 1978

Contract EY-76-C-11-0014

P r in t ed i n t h e United. S t a t e s . o f America Avai lable from t h e

National Technical Information Serv ice U. S. Department of Commerce

5285 Por t - Royal Road . Spr ing f i e ld , V i rg in i a 22151

NOTICE

sponsored by the United States Government. Neither the United States nor the United Stater Department ol. Energy, nor any of their employees, nor any of their ronlnaclunr. .ubcu##traclun. or rhelr employees, mkr~ any warranty, express or implied, or auumcs any legal liability or responsibility for the accuraey.complcteneu or ua fdncs l of any information, apparatus, product or Procen disclosed, or represents that its use would not

NOTE

This document i s an i n t e r i m memorandum prepared p r imar i ly f o r i n t e r n a l r e f e r - ence and dpes not r e p r e s e n t ' a f i n a l expression o f t h e opinion of Westinghouse. When t h i s memorandum i s d i s t r i b u t e d e x t e r n a l l y , it i s wi th t h e express under- s tapding t h a t Westinghouse makes no r e p r e s e n t a t i o n a s t o completeness, accuracy, or u s a b i l i t y ' o f information cont,ain~tcf t,herei n .

BETTIS ATOMIC POWER LABORATORY WEST MIFFLIN, PENNSYLVANIA

Operated f o r t h e U. S. Department o f Energy by WESTINGHOUSE ELECTRIC'CORPORATION

This repor t w a s prepared a s an account of work sponsored by t h e United S t a t e s Government. Neither t h e Uni ted .S ta tes ,nor t h e United S t a t e s Department p f Energy, nor any of t h e i r employees, nor any of t h e i r contrac tors , subcon- t r a c t o r s , o r t h e i r employees, make any warranty, express o r implied, o r assumes any l e g a l l i a b i l i t y o r r e s p o n s i b i l i t y f o r t h e accuracy, completeness o r usefulness of any information, apparatus, product .or process disclosed, o r represents t h a t i t s use would not in f r inge p r iva te ly owned r i g h t s .

TABLE OF CONTENTS

I. INTRODUCTION

11. TEST DESCRIPTION

111. PREVIOUSLY REPORTED EQUILIBRIUM ISOTHERMAL DATA

I V . NEW TEST RESULTS

A. Simulated LOCA Trans ien ts B. E f f e c t of Test Procedures C . . Single-Test Specimen Test Data

V I . ADDITIONAL TESTING AT 1 5 6 2 ' ~ ( 8 5 0 ' ~ )

V I I . SUMMARY

REFERENCES

Table

LIST OF TABLES

T i t l e

I L i s t o f Single-Test High Temperature Tes t Data I1 I n i t i a l p red ic t ion Model Proper ty F i t Constants ,111 Resul t s of Addi t iona l Tes t s a t 85o0C I V ~ i n a l P red ic t ion Model Property FTt 'Constants

LIST OF FIGURES

Figure T i t l e

d Schematic of Test Apparatus Comparison of Isothermal Pred. ic t ions t o Measured Data LOCA Temperature Trans ien t Sinlulatkons E f f e c t of Test procedure Upon S t r a i n Accumulation ( 1 6 0 0 ' ~ . - 750 p s i Hoop S t r e s s ) 'Ef fec t o f Test Procedure Upon S t r a i n Accumulation ( 1 8 0 0 ~ ~ - 500 p s i Hoop.St ress ) E f f e c t of Test Procedure Upon S t r a i n Accumulation ( 2 0 0 0 ~ ~ - 500 p s i Hoop s t r e s s ) Comparison of Steady-State S t r a i n Rate S t r a i n Rate Sens . i t i v i ty Var ia t ion With Temperature Comparison of I n t e r c e p t Hoop S t r a i n i n t h e a + B and B Regions Comparison of Predic ted and Measured S t r a i n Comparison of P red ic t ions t o t h e Reference (11) Data

Page - 1'

2 .

Page -

iii

LIST OF FIGURES ( ~ o n t )

F igure T i t l e

1 2 Comparison of P r e d i c t i o n s t o t h e Reference (11) Data 1 3 Comparison of P r e d i c t i o n s t o t h e Reference (11) Data 14 Comparison o f P red ic t ed and Measured Diametral S t r a i n 15 Schematic o f Tes t Apparatus 1 6 Typica l Tes t Temperature His tory 1 7 Comparison of ~ e s t ' ~ a t a and P red ic t ion Models

Page

Tests of closed-end, internally pressurized, Zircaloy-4 tubing specimens were utilized to develop low strain creep characteristics as a function of time at temperatures in the range of 1475'~ ,to 2000°F ( 8 0 2 ~ ~ to 1 0 9 3 ~ ~ ) and hoop stresses .in the range of 250 to 2500 psi for use in loss-of-coolant accident (LOCA) analyses. The strain rate above the start of the alpha to beta phase transformation reg?on,' approximately' 1 4 9 0 ~ ~ (810°c), was found to be sensitive to the test procedure (stress-temperature history). This is believed to result from variations in the metal- lurgical structure. ,A prediction mode1,is pre- sented whic'h provides a conservative upper bound to %he low strain test data provided in this report and reported in the literature.

LOW STRAIN DIAMETER EXPANSION OF INTERNALLY PRESSURIZED ZIRCALOY-4 TUBING AT HIGH TEMPERATURES

( LWBR Development Program)

L. S. White and. C, C. Busby

I. INTRODUCTION

During a postulated loss-of-coolant accident (LOCA) for a pressurized water

reactor (PWR), the sudden system depressurization and attendant loss of coolant

flow imposes, .on the fuel elements, high cladding temperatures which exist simul-

taneously with a rod internal gas pressure higher than that of the external sys-

tem pressure. As a result, large diameter expansion, and possible bursting are

of concern. This report presents the results of testing the response of

Zircaloy-4 tubing to the LOCA hoop stress-temperature environment. An analysis

model is also presented which may be used in assessing fuel element low strain

plastic diameter expansion during a LOCA. This testing is a continuation of the

testing reported in.Reference (1) and was accomplished as part of the Light Water

Breeder Reactor (LWBR) fuel element development effort.

High temperature test data previously reported have generally established

only the stresses and strains associated with burst or fracture, for example,

~eferences (2) through (5). The tests described in this report, which are a

continuation of those reported in Reference (I), were initiated to obtain the

stress sensitivity at relatively low strain (less than 5 percent diametral

expansion) over the temperature range from 1475O~ to 2000°F (802'~ to 1093'~).

The low s t r a i n information i s of i n t e r e s t i n r eac to r design t o determine t h e

e f f e c t of c l ad expansion on coolant channel dimensions and p o t e n t i a l flow con-

s t r i c t i o n . For t h e t e s t specimens used i n these t e s t s , t h e a lpha t o b e t a phase

t ransformat ion region ranges from approximately 1 4 9 0 ' ~ (810°C) t o approximately

1770°F ( 9 6 5 O ~ ) . Test procedures were va r i ed t o assess t h e r e l a t i v e e f f e c t s of

t h i s phase t ransformat ion on t h e p l a s t i c s t r a i n and s t r a i n - r a t e sens i t iv i ty . .

11. TEST DESCRIPTION

The specimens used i n t h i s t e s t were 13 inches long, 0 .31 inch OD

x 0.26 inch I D cut from. 68 percent tube reduced and r e c r y s t a l l i z e d (5-6 hours

a t 1225OF) zircaloy-4 tubing. One end was sea led with a welded Zircaloy-4 plug

and t h e o the r end was connected t o t h e pressur iz ing system with a Swagelok

f i t t i n g . The specimens were cut from tubing with measured maximum w a l l th ickness

e c c e n t r i c i t y ( u l t r a s o n i c measurements) between 0.0004 inch and 0.0006 inch. The

average w a l l th ickness of each specimen was ca lcu la ted from t h e dens i ty

(6.54 gm/cc) , t h e specimen length measured t o 0.001 inch, and t h e average outs ide

diameter based on micrometer measurements (0.0001 inch) f o r two diametral posi-

. t i o n s a t f i v e pos i t ions along t h e length. This average wall th ickness was used

i n t h e fol lowing th in-wal l formula t o obtain t h e required i n t e r n a l pressure f o r

t h e des i red hoop s t r e s s :

where .

a = hoop s t r e s s i n p s i 8 P = i n t e r n a l gas pressure i n p s i

D = mean diameter i n inches

t = average wall th ickness i n inches.

The specimens were heated by placing them i n a 1 1/4-inch Vycor chamber

loca ted a t t h e a x i s of a dual e l l i p t i c a l - r e f l e c t o r , quartz-lamp furnace as shown

i n Figure 1. A s i l icon-contro l led a-c power c o n t r o l l e r with thermocouple feed-

'back provided a closed-loop system t o maintain accura te ly t h e des i red temperature.

Inves t iga t ion showed t h a t t h e maximum tempdrature, uniform within +5OF, was

obtained a t a d is tance of 3 1 /2 t o 5 1/2 inches from t h e welded end of the\ sample.

The d a t a repor ted here in a r e based upon measurements a t t h e 4 1/2-inch locat ion .

Temperatures were recorded by t h r e e Chromel-Alumel thermocouples, two i n t e r n a l

and one ex te rna l . The beads of t h e inner thermocouples were exposed through

windows cut i n a ceramic insu la t ion which projected through t h e Swagelok

connection of t h e apparatus and t o w i th in 1 1 4 inch of t h e welded end p lug . How-

ever , thermocoi~ple head contac t w i th t h e specimen was avoided t o preclude r e a c t i o n

wi th t h e Zi rca loy . The su r f ace thermocouple was i n contac t wi th t h e specimen,

bu t r e a c t i o n w a s prevented by enclo'sing t h e bead i n 0.002-inch tantalum f o i l .

The o u t s i d e and one of t h e inne r thermocouples were loca t ed a t t h e 4.112-inch

"hot spot . " The second inner thermocouple was loca t ed 7 inches from t h e welded

end where t h e temperature was 50-60 '~ lower.

Oxidation of t h e specimens was e s s e n t i a l l y e l imina ted by evacuat ing t h e

Vycor chamber and t h e specimen t o F . 5 1 ~ pressure p r i o r t o hea t ing , maintaining a

dynamic vacuum i n t h e Vycor chamber throughout t h e t e s t , and us ing i n e r t argon

gas t o p r e s s u r i z e t h e specimens. The e f f ec t , o f temperature on t h e specimen g a s

p re s su re w a s effectively.neutralized, and t h e r e f o r e cons tan t hoop s t r e s s could

be maintained during t h e t e s t , by t h e r e l a t i v e l y l a r g e volume r a t i o (approxi- '

mately 2 0 : l ) o f t h e system e x t e r n a l p ip ing t o t h e specimen.

Two dual-pen s t r i p c h a r t r eco rde r s were u t i l i z e d t o monitor specimen pres-

su re and t h e specimen sur face and i n s i d e temperatures throughout t h e t e s t .

I1 I . PREVIOUSLY REPORTED EQUILIBRIUM ISOTHERMAL DATA

The o b j e c t i v e of t h e i n i t i a l phase of t e s t i n g descr ibed i n Reference (1)

was t o o b t a i n i 'sothermal d a t a , unaf fec ted by phase t ransformat ions ( equ i l i b r ium

s t r u c t u r e ) which could be used t o formulate a low-s t ra in , high-temperature c r eep

model. The specimens were slowly heated t o t h e ' t e s t temperature while evacuated.

P r i o r t o p r e s s u r i z a t i o n , approximately two t o seven m i n u t e s . a t t h e t e s t tempera-

t u r e was allowed f o r temperature and s t r u c t u r e e q u i l i b r a t i o n . Each specimen

a f t e r b e i n g ' s t r e s s e d f o r a p re se l ec t ed t ime per iod was depressur ized and c o o l e d .

t o room temperature f o r diameter measurements. The specimen was then r e t e s t e d

f o r a d d i t i o n a l t ime per iods (same s t r e s s and temperature) u n t i l a s t eady- s t a t e

r a t e was observed o r i n s t a b i l i t y occurred. Ind iv idua l t e s t t imes , depending on

t h e s t r e s s , temperature, and whether o r no t t r a n s i e n t o r s teady-s ta te behavior

was expected, were a s sho r t a s 3 seconds and a s long a s 1 5 minutes.

These t e s t d a t a a r e r epo r t ed i n Reference (1). Also presented i n Refer-

ence (1) i s an . i so the rma l p r e d i c t i o n model which w a s formulated t o g ive a con-

s e r v a t i v e upper bound t o t h e t e s t d a t a as shown i n Figure 2 . These d a t a and

model were then used as a base f o r i n v e s t i g a t i n g t h e e f f e c t s of nonequilibrium

s t ruc ' tu re on t h e s t r a i n r a t e .

IV. NEW TEST RESULTS

A. Simulated LOCA Transients

After completing the isothermal testing reported in Reference (1) , testing of specimens subjected to representative LOCA high temperature histories was ini-

tiated. The intent of this testing was to investigate the adequacy of the iso-

thermal prediction model in predicting strain during a temperature transient.

The specimens were pressurized at normal PWR operating clad temperatures and

heated as shown in Figure 3. The diametral strain was measured after the speci-

mens were depressurized and cooled to room temperature and compared to the pre-

dicted strain, which was obtained by using the Refe.rence (1) isothermal prediction

model. This comparison, shown in Figure 3, shows the Reference (1) model conser-

vatively predicted the measured strain only for that transient which stayed

entirely within the alpha region, i.e., temperatures less than 1 4 9 0 ~ ~ (810~~).

The two higher peak temperature transients which entered the alpha + beta and beta regions are underpredicted. Thus, it was concluded that the equilibrium

test data could not be used to conservatively predict strain d~iring a LOCA tran-

sie11.t that experienced temperatures higher than the alpha transition temperature.

B. Effect of Test Procedures

The disagreement between the predictions based upon the Reference (1.) model

and the plastic strain obtained from the simulated LOCA temperature transien%s

led to additional testing at faster initial heatup rates and an investigation of

the e.ffect of the equilibration hold . time . at test temperature prior to pressuri-

zation. A datatrak programmer was used to control the furnace voltage to enable

accurate repeatability of temperature transients. Figures 4 through 6 show the effect of varying the test procedure upon the measured diametral strain. The

Reference (I) isothermal test samples were heated slowly to the test temperature

(usually taking 15-20 minutes from room temperature to test temperature) and then

give11 an equilibration time of 2 t.0 '( minutes prior to pressurization. It was

found that this equilibration time prior to pressurization has a ma.rk.crd effect

on the strain rate at 1600~~ to 1800~~ ($71'~ to 982O~) isothermal test tempera-"

tures. At 1 6 0 0 ~ ~ (871°c) the strain rate is reduced slightly for the zero time

delay specimens. At 1800'~ (982OC), however, the trend is reversed and decreased

equilibration time results in increased strain rates. Equilibration tjme at

2000°F (1093~~) shows essentially no effect on the strain rate for the two

"multi-testt' specimens. Figures 5 and 6 also show the difference between a "multi-test" specimen which was subjected to numerous heating, pressurization,

depressurizat ion, and cooling cycles and "single-test" specimens which experi-

enced only one cycle. A small nearly constant s t r a i n increment i s observed a t

1 8 0 0 ' ~ ( 9 8 2 ' ~ ) ~ but a t 2000 '~ ( 1 0 9 3 ' ~ ) ~ a s ign i f i can t increase i n t h e s t r a i n - r a t e

was observed.

The va r ia t ions i n s t r a in - ra te and amount of accumulated p l a s t i c s t r a i n

observed'for t h e d i f f e r e n t experimental procedures i s pos tula ted t o be due,

primari ly, to . t h e f a c t t h a t m y t h e s t r a in - ra te ~ e n s i t i v i t y , * i s highly dependent

on t h e s t r a h - r a t e range, temperature and/or t h e p a r t i c u l a r crys ta l lographic

phase or combination of phases present i n t h e mater ia l during t h e t e s t . Depend-

ing on t h e experimental procedure, both t h e type and t h e r e l a t i v e amount of

crystal lographic ' phases can vary even a t t h e same t e s t temperature. ~ u r i n ~ t h e

i n i t i a l heating i n t h e "multi-test" procedure, primary o r equi-axed alpha t r a n s -

forms . t o $ which, upon rapid cooling, retransfqrms t o t h e ac icu la r alpha s t ruc-

tu re , a ' . Therefore, t h e s t ruc tu re of t h e "multi-test" specimen during heat ing

f o r subsequent . tes ts . . would be unlike t h a t present i n t h e i n i t i a l run of t h a t

specimen o r i n t h e "single-test" specimen, and t h i s d i s s i m i l a r i t y might possibly

contr ibute t o d i f ferences i n transformation rat .es and/or s t r a i n accumulation.

I n general , s train-r .ate s e n s i t i v i t y increases with decreasing s t ra in - ra te and/or.

increasing temperature, reaches a maximum i n t h e alpha plus be ta phase f i e l d ;

and then decreases again a s t h e s t ruc tu re becomes predominantly be ta Zircaloy,

Reference. ( 6 ) . The s t ra in - ra te s e n s i t i v i t y normally observed f o r alpha Zircaloy

i s about 0.2 o r l e s s . ~ o w & e r , it increases sharply i n t h e alpha plus be ta region

and can a t t a i n a maximum value of un i ty , Reference ( 6 ) . The w l u e of 'm i s a r e l a -

t i v e meas.ure of t h e amount of p l a s t i c s t r a i n which can be t o l e r a t e d p r i o r t o t h e

onset of unstable flow and the re fo re high values of m a r e consis tent with

extremely l a r g e . p l a s t i c extentions. A mater ia l i s considered t o exhibi t super-

p l a s t i c behavior i f t h e s t r a in - ra te s e n s i t i v i t y i s about 0 .3 o r higher. A s s t a t e d

i n Reference ( 7 ) ; the maxim~lm superp las t i c i ty has' beep found near the ' center of

t h e two-phase region, i . e . , when t h e phases a r e p resen t i n 'nearly equal propor-

t i o n s . Under equilibrium condit ions, the percentages of alpha and beta Zircaloy

w i l l be t h e -same...at about 1 6 . 5 0 ~ ~ ' (89goc),. Therefore, i n t e s t s performed a t ' tem-

. pera tures where t h e a phase would s t a r t t o transform t o t h e $ phase, i . e . , above

approximately 1 4 9 0 ' ~ ( 8 1 0 ' ~ ) ~ t h e time a t temperature p r i o r t o load appl ica t ion

would have an e f f e c t on t h e r e s u l t i n g s t ra in - ra te and amount of p l a s t i c s t r a i n

ac&mulated.. A t . temperatures below 1 6 5 0 ' ~ ( 8 9 9 ' ~ ) ~ e .g. , 1600.'~ (871°c), a long

*m = A(3.og n ) / f i ( l n g 6 ) at, constant temperature and p l a s t i c s t r a i n where a = t r u e ' ~ t r e ~ ~ and i = t r u e s t r a in - ra te .

e q u i l i b r a t i o n period, as opposed t o a shor ter or zero equ i l ib ra t ion time, would

r e s u l t i n t h e most near ly equil ibrium composition and t h e transformation of t h e

maximum amount of a t o B cons i s t en t with t h e t e s t temperature. This composition

would more c l o s e l y approach t h a t (50 perc.ent each of a and 6 ) a t which maximum

superplast ic ' i ty i s observed and the re fo re more s t r a i n would be expected f o r a

long e q u i l i b r a t i o n time specimen than for shor te r or 'no-delay specimens which

would conta in l e s s of t h e B and more of t h e a phases. Conversely, f o r tempera-

t u r e s above 1 6 5 0 ~ ~ ( 8 9 9 O ~ ) , e . g . , 1800°F ( 9 8 2 O ~ ) , a long equ i l ib ra t ion would

al low t h e specimen t o transform almost e n t i r e l y t o t h e B phase, whereas a no-delay

specimen would be s t r e s s e d while transformation i s occurring. More s t r a i n , t.here-

f o r e , would be developed i n t h e no-delay specimen.

C. Single-Test Specimen Test Data

Based upon t h e preceding discuss ion, it was concluded t h a t predic t ions of

t h e d iametra l s t r a i n during a pos tula ted LOCA would be conservative a t tempera-

t u r e s below 1 6 0 0 ~ ~ (871 '~ ) when using t h e Reference (1) clad expansion model.

A t temperatures above 1 6 0 0 ~ ~ (871°c), however, t h e Reference (1) model would

underpredict t h e s t r a i n . Therefore, .addi t ional t e s t i n g was performed.to define

t h e s t r e s s - s t r a i n behavior a t t h e higher temperatures. Measurements (were

obtained on s ing le - t es t specimens which were pressurized a t room temperature,

ramped a t lG°F/sec (g°C/sec) t o t h e t e s t temperature, held a t t h e isothermal

t e s t temperature f o r a predetermined time i n t e r v a l , depressurized and' cooled t h

room temperature fo r measuring. Only one t e s t point per specimen was obtained

so each t e s t may be viewed a s a control led LOCA t r a n s i e n t up t o t h e point of t h e

evacuation and cooldown. The da ta obtained i n t h i s manner a r e shown i n Table I .

Figure 7 compares t h e s ing le - t es t specimen steady-state r a t e s with those

repor ted i n Reference (11 . . The increased s t r a i n - r a t e s e n s i t i v i t y at 1800°F

(982%) i s c l e a r l y evident . Figure 8 shows t h a t t h e s t r a i n - r a t e sensi . taivi ty

versus temperature v a r i a t i o n obtained i n t h i s phase of t e s t i n g compares favorably

with t h a t repor ted i n Reference (8) . .

The specimens used i n t h i s t e s t i n g were taken from r e c r y s t a l l i z e d annealed

(RXA) tubing. A t normal operat ing temperature i n pressurized water r eac to r s '

(below 700°F (371°c)) , t h e s t r e s s - r e l i e f annealed (SU) tubing has higher i n i t i a l

s t r eng th and increased res i s t ance t o thermal creep. However, a t high temperatures

(above 1 4 0 0 ' ~ (7606c) ) , t h e SRA mater ia l tends t o recrystallize i n j u s t a few

seconds, as evidenced by t h e metallographic examinations reported i n Reference ( 9 ) . Also, Reference (10) ind ica tes no s ign i f i can t d i f ference i n s t r a i n r a t e s f o r RXA

and SRA specimens f o r isothermal t e s t temperatures i n t h e high temperature alpha

range, 1472OF ( 8 0 0 ' ~ ) . For f u r t h e r v e r i f i c a t i o n i n t h e a + B and B regions ,

t h r e e specimens of 70-percent C.Wi ( f i n a l reduction) and S R A . ( ~ ~ O ~ F / ~ hours) .' tube-reduced tubing were t e s t e d during t h e current inves t iga t ion . Per t inent

da ta f o r these specimens which were pressur ized a t room temperature, heated a t

approximately 7-ll°F/sec (4-Goc/sec) . and he ld a t t h e isothermal te . s t tempera-

t u r e f o r a se lec ted time i n t e r v a l a r e shown i n Table I and Figure 10.

During t h e i n i t i a l blowdown phase of t h e LOCA t r a n s i e n t , t h e predic ted

.cladding temperature sometimes experi'ences a r e l a t i v e l y high temperature "spike. It

A t t h i s 'time i n t h e LOCA t r a n s i e n t , t h e system pressure i s s t i l l higher than t h e

f i e i rod i n t e r n a l gas pressure and the re fo re no diametral expansion w i l l occur.

This temperature excursion above t h e alpha-beta t r a n s i t i o n temperature, however,

could a l t e r subsequent phase transformations and m a t e r i a l s t r eng th , thus af f e c t -

ing t h e s t r a i n r a t e . Therefore, inves t iga t ion of poss ib le temperature-spike

e f f e c t s was undertaken.

.The specimens of Reference ( 9 ) were subjected t o peak temperatures of

1770°F ( 9 6 6 ' ~ ) and 1 4 9 0 ~ ~ . (810'~) p r i o r t o being t e s t e d a t 1 4 7 5 ~ ~ ( 802Oc.) and

1400°F ( 7 6 0 ~ ~ ) . No d i sce rn ib le d i f ferences i n s t r a i n accumulation 'are evident

i n conipariilg these d a t a t o t h e t e s t da ta of References (1) and ( 2 ) which d i d

not include any pre-test temperature t r a n s i e n t . Two spiked samples were t e s t e d

i n t h e a + B and B regions during t h e current t e s t program. These specimens

were heated, uns t ressed , t o peak temperatures of 1850°F ( 1 0 1 0 ~ ~ ) -and 1720°F

( 9 3 8 ' ~ ) and l a t e r t e s t e d a t temperatures of 1800°F (982Oc) and 1 6 0 0 ' ~ (871°C).

The time of t h e simulated temperatkre spike above t h e transformation temperature .

was approximately 15-20 seconds. Table I shows t h e t e s t condit ions f o r t h e two

temperature-spike specimens; t h e r e s u l t i n g p l a s t i c d iametra l s t r a i n s are p l o t t e d

. in Figure 10. A s shown,'the two specimens a re wel l predic ted by the. ana lys i s

model.

V. LOW-STRAIN CLAD EXPANSION MODEL

A c lad expansion model has been formulated f o r use i n p red ic t ing t h e low-

s t r a i n c lad expansion which may occur during a pos tu la ted LOCA t r a n s i e n t . The

d.iamet,ra.l s t r a i n i.s given by:

where

~ ( t ) = t o t a l p l a s t i c hoop s t r a i n a t time t -

( E = maximum in te rcep t s t r a i n i n t h e time i n t e rva l from 0 t o t

i = steady-state s t r a i n r a t e . ss

The in te rcep t s t r a i n i n the 'above equation , is t h e s t r a i n obtained by extrapo-

l a t i n g t h e steady-state r a t e back t o time zero and includes any instantaneous

loading s t r a i n and the primary o r t r ans ien t s t r a i n . Figure 9 shows in tercept

s t r a i n i n t h e a + 6 and 8 regions obtained from'the current t e s t i n g and t he

o r i g i n a l Reference (1) isothermal t e s t s . A s i s t yp i ca l a t these temperatures,

a ' large amount of data s c a t t e r i s observed. For temperatures of 1 6 0 0 ' ~ (871 '~)

and below, t h e expression used i n Reference ( l) , E = A U ~ , gives an adequate f i t

t o t h e t e s t data. A t t h e higher temperatures, an expression of t he form

E = C exp (DO) i s used t o give a conservative estimate zt t h e low.er s.l;resu l eve l s .

Therefore, t he in te rcep t s t r a i n may be calculated by:

where -

, E = in te rcep t hoop s t r a i n

u = hoop s t r e s s ( p s i )

A, B , C , D = property f i t constants (fbnction 'of temperature).

Figure 7 shows t h a t t h e steady-state s t r a i n r a t e s may be expressed by:

where .

E = steady-state hoop s t r a i n r a t e ( l / s e c ) s S

u = hoop s t r e s s ( p s i )

K , n = property f i t constants (function of temperature).

The property f i t constants a r e defined a t severa l reference temperatures.

The i n t e r cep t s t r a i n and steady-state s t r a i n r a t e i s calculated a t two reference

temperatures, and the following equation i s used t o in te rpo la te t o t he desired

temperature:

log E ( T ) - log E ( T ~ ) I/T - 1 / ~ ~

log € ( T k ) - log Z ( T ~ + ~ ) = l / T k - l / T k c l

where

T = temperature i n quest ion ( O K ) '

Tk, Tk+i = reference temperature ( O K )

l o g c ( ~ ) : = l o g of ;. o r P s:s, f o r .temperature T

l o g E ( T ~ ) = log of o r i evaluated a t temperature T s s k

l o g E (T ) = l o g 'of o r i evaluated a t temperature T k + l s s k+l '

Table I1 shows t h e se lec ted property f i ' t constants . Figures 7 and 9 show t h a t

these constants a r e se lec ted t o upper bound t h e . t e s t d a t a and thus provide a

reasonably conservative predic t ion t o t h e low-strain c l ad expansion.

C

Figure 10 compares the .p red ic ted and measured diarqetral s t r a i n from t h e

current t e s t . This f igure shows t h a t t h i s new model conservatively p r e d i c t s t h e

simulated LOCA t r a n s i e n t t e s t specimen s t r a i n s . Also, t h e SRA and temperature-

spike t e s t da ta agree we l l with t h e r e s t of t h e d a t a s e t , i nd ica t ing no major

e f f e c t s i n high temperature s t r a i n accumulatiori r e s u l t i n g from ;old work o r

pre- tes t temperature spikes.

Reference (11) presents diametral expansion d a t a obtained by p ressur i z ing

t h e t e s t specimens a t room temperature and then ramping t h e temperature a t a

r a t e df 45O~/sec ( 2 5 O ~ / s e c ) . Figures 11 through 13 show t h a t t h e predic t ion

model presented i n t h i s rep.ort adequately p r e d i c t s diametral s t r a i n s up t o a t

l e a s t 3 percent over a temperature range of 1475O~ t o 2000°F (803OC t o 1083O~) .

Figure 1 4 compares t h e model predic t ions t o isothermal t e s t d a t a of Refer-

ence (12) . Good agreement, i s obtained, with t h e exception of t h e 1562O~ ( 8 5 0 ~ C )

t e s t d a t a i n which t h e measured s t r a i n s a r e considerably highyr than t h e model

predic t ions.

V I . ADDITIONAL TESTING AT 1562O~ ( 8 5 0 ' ~ )

I n order t o resolve t h e d.i.fference hetween t h e predic t ions and t h e Refer-

ence (12) d a t a at. 1 5 6 2 ' ~ (850°c), an add i t iona l s e r i e s of t e s t s was performed.

For these t e s t s , a modified t e s t procedure was used so a s t o reproduce as

closely. a s poss ib le t h e heat ing r a t e s a t which t h e da ta repor ted i n Reference (12)

. were obtained.

The t e s t specimens used f o r t h e s e t e s t s were 6 inches long and were cut

from t h e same r e c r y s t a l l i z e d zircaloy-4 tubing u t i l i z e d f o r t h e previous. t e s t s .

One end was sealed with .a s o l i d ~ i r c a l o ~ - 4 plug by welding and t h e o ther end

was welded t o a pressur iz ing stem which was sea led following p ressur i za t ion of .

t h e specimen a t room temperature.. ..Following p ressur i za t ion with argon gas , a

. Chromel-Alumel thermocouple was .t ack-welded t o t h e specimen. React ion was pre-

vented by enclosing t h e bead i n 0.002-inch tantalum f o i l . The t.hermocoup.le

wires were i n s u l a t e d by .a 0.1-inch-diameter ceramic rod which was wired t o t h e

specimen and a l s o used t o support t h e specimen. The specimen was then placed

i n a 5/8-inch Vycor tube as shown i n Figure 15. The ceramic rod extended i n t o

a "necked" por t ion of t h e Vycor tube . Epoxy was used t o s e a l t h e tube with t h e

thermocouple wires extended t o a dual-pen s t r i p chart recorder. The Vycor tube

was f i r s t evacuated and then b a c k f i l l e d with i n e r t argon gas t o ac t a s a heat

t r a n s f e r medium. The argon pressure was such t h a t a t t h e 1562'~ ( 8 5 0 ' ~ ) t e s t

temperature, t h e pressure e x t e r n a l t o t h e specimen was one atmosphere. The

i n t e r n a l gas was i n s e r t e d a t room temperature such t h a t a t 1 5 6 2 ~ ~ ( 8 5 0 ~ ~ )

t h e d e s i r e d hoop s t r e s s was achieved, a s ;alculated by using t h e i d e a l gas law.

The e n t i r e assembly was then i n s e r t e d . i n t o a resistance-wound, 2 1/2-inch-

diameter tube f'urnac.e. The thermocouple was located 24 inches from t h e open end

i n t h e "hot' zone." Inves t iga t ion showed a uniform temperature d i s t r i b u t i o n over

+1 i.nch a t t h i s locat ion . A l l s t r a i n measurements were taken i n t h e v i c i n i t y

of t h e thermocouple a t room temperature.

The heat ing r a t e f o r t h e t e s t specimens reported i n Reference (12) was

es t imated t o have been 72 t o gO°F/sec (40 t o 50°C/see). The heat ing r a t e used

f o r t h e s i n g l e t e s t specimens discussed i n Section 1 V . C of t h i s repor t was

approximately lG°F/sec ( g O ~ / s e c ) i n t h e a-B transformation region. The l imi ta-

t i o n s of t h e resistance-wound tube furnace used f o r t h e revised t e s t procedure

r e s u l t e d i n a r e l a t i v e l y slow heatup r.ate. Figure. 16 shows a t y p i c a l tempera-

t u r e h i s t o r y f o r t h i s t e s t . In t h e a-B transformation region, t h e heat ing r a t e

i s approximately l . l ° F / s e c ( 0 . 6 O ~ / s e c ) . The specimens used i n t h e s e t e s t s were

p ressur i zed and sealed and thus were s t r e s s e d during t h e e n t i r e time while they

were being heated t o t h e t e s t temperature. The low heating r a t e r e su l t ed i n t h e

specimens being s t r e s s e d during t h e time when t h e temperature i s below t h e t e s t

temperature, but a t a temperature high enough t o r e s u l t i n measurable permanent

s t r a i n . I n order t o l i m i t t h i s a d d i t i o n a l s t r a i n accumulation, t h e 5-minute

"isothermal" t e s t time was s t a r t e d a t 1 5 4 4 ' ~ (840 '~) i n s t e a d ' o f 1 5 6 2 ' ~ ( 8 5 0 ' ~ ) .

Five specimens, with hoop s t r e s s e s ( a t t h e t e s t temperature) ranging from L

250 t o 1250 p s i , were t e s t e d using t h i s revised t e s t procedure. Table I11 pre-

s e n t s t h e r e s u l t s of t h e s e a d d i t i o n a l t e s t s . Figure 17 compares these addi-

t i o n a l t e s t d a t a with t h e Reference (12) t e s t d a t a and t h e predic t ion model

using t h e Table I1 proper ty f i t ' const;ants. Figure 17 shows t h a t t h e measured

s t r a i n s a r e less . , than those.repoSt'ed, i n Reference ( 1 2 ) , b u t a r e s u b s t a n t i a l l y

higher than t h e predict ion.

The underprediction of t h e model i s most l i k e l y due t o t h e use of t h e mult i-

test-spec'imen da ta obtained a t 1 6 0 0 ~ ~ (871°C) property constants shown i n

Table 11. he i n a b i l i t y of t.he predict ion, model based on use of t h e mul t i - tes t -

specimen d a t a t o predic t t h e single-test-specimen da ta may be due t o t h e p a r t i a l

t ransformation t o t h e B phase which occurred on heat ing during t h e i n i t i a l .run.

This phase would retransform t o a c i c u l a r a phase upon cooling t o room tempera-

ture. ' The presence of t h e a c i c u l a r a 'phase could poss ib ly a f f e c t t h e s t r a i n -

r a t e s e n s i t i v i t y when t h e specimen i s reheated t o t h e t e s t temperature f o r

subsequent t e s t i n g .

The reason f o r t h e disagreement between t h e single-test-specimen da ta a t

1 6 0 0 ~ ~ . (871°C) presented i n t h i s repor t and t h a t presented i n Reference (12) can

. not be d e f i n i t e l y determined a t t h i s time. The most probable explanation i s

t h a t t h e s t r a i n r a t e i n t h i s temperature region i s a complex function of present

and ' p r io r phase transformation a s we l l a s t h e c l a s s i c a l Gariables ' such a s tem-

pera ture , s t r e s s , and s t r a i n s t a t e . Figure 17 shows t h a t a l l of t h e io; s t r a i n

t e s t d a t a i n t h i s temperature region may be conservatively predic ted by using

t h e 1700°F ( 9 2 7 ' ~ ) property constarks of Table 11. Therefore, t h e property

constants showr' in Table I V can be used f o r conservatively p red ic t ing low s t r a i n

behavior (53%) a t temperatures between 1475OF ( 8 0 2 ~ ~ ) and 2000°F (1093 '~ ) .

V I I . SUMMARY

This repor t presents high temperature, low s t r a i n t e s t da ta f o r p r e s s w i z e d

Zircaloy-4 tubing relevant t o a pos tu la ted LOCA. The measured hoop s t r a i n s were

found t o be very sens i t ive t o t h e t e s t procedure at temperatures above t h e a-B

transformation temperature f o r Zircaloy. This s e n s i t i v i t y i s a t t r i b u t e d t o time-

dependent ma te r i a l , micro-structural t ransformation and t h e r e s u l t i n g impact on

superplast i c i t y . This s e n s i t i v i t y should be accounted f o r i n developing t e s t s

and models , for use i n predic t ing t h e response of t h e cladding t o a r ap id LOCA

t r a n s i e n t . Also presented i n t h i s repor t i s a. low s t r a i n predic t ion model which

has been shown t o give conservative predic t ions t o simulated LOCA t r a n s i e n t s and

o ther da ta s e t s obtained by' d i f f e r e n t t e s t procedures. This model i s v a l i d f o r

, pred ic t ing diametral s t r a i n s up t o a t l e a s t 3 percent over a temperature range

of 1 4 7 5 ' ~ t o . 2000°F ( 8 0 2 ~ ~ t o 1 0 9 3 ~ ~ ) .

REFERENCES

(1) C. C . Busby and L. S: White, "Some -High Temperature Mechanical Proper-

t i e s o f I n t e r n a l l y P re s su r i zed zircaloy-4 Tubing," w , A P D - T M - ~ ~ ~ ~ ,

February 1976. .

( 2 ) C. C . Busby and K. B. Marsh, "High Temperature Deformation and Burst

C h a r a c t e r i s t i c s of R e c r y s t a l l i z e d Zircaloy-4 Tubing," WAPD-TM-900,

January 1970.

( 3 ) "Performance of Z i r ca loy Clad Fuel Rods During a Simulated Loss-of-

Coolant Accident - S i n g l e Rod Tes t s ," WCAP-7379, Volume 11,

September 15 , 1969.

( 4 ) D. 0. ~ o b s o n , ' M . F. Osborne, and G. W. ~ a r k e r , "Comparison of Rupture

Data from I r r a d i a t e d Fuel Rods and Un i r r ad ia t ed Cladding," Nuc1ea.r

Tec!ulology., V~1.une 11, yp. 479-490, Aiigl~st 1971.

( 5 ) J. F. White, "Physico-Chemical S tud ie s of Clad U02 Under Reactor Acci- --

dent Condit ions ," GEW-1012, ~ a r t 11, pp. 203-252,. March 31, 1969.

( 6 ) J. J. Kearns, J. E. McCauley, and F. A. Nichols , "Effect of Alpha/Beta.

Phase Cons t i t u t ion on S u p e r p l a s t i c i t y and St rength of Zircaloy-4,"

J. Nucl. Mater. 61, 169-184, 1976.

( 7 ) R . H. .Johnson, "Supe rp la s t i c i t y , " Metals and Mate r i a l s , Volume 4 ,

No. 9 , . September 1970.

(8) D. Lee and W. A. Backofen, " S ~ p e r ~ l a s t i c i t y , i n Some Titanium and Z i r -

conium Alloys ," Trans. of AIME, Volume 239, pp. 1034-1040, J u l y 1967.

( 9 ) C. C . Busby and K . B. Marsh, "High Temperature, Time-Tlepnil~nt Tlefor-

m a t ion of I n t e r n a l l y P re s su r i zed Zircaloy-4 Tubing ," wAPD-TM-1043,

October 1974.

( 1 0 ) B. D. Clay and G. B. Redding, "The Stress-Rupture Tes t ing of Z i r ca loy

Tube at 800°c," Cen t r a l E l e c t r i c i t y Generating Board, Berkely Nuclear

Labora tor ies Report 'RD/B/N 3129, 1974.

(11) D. G . Hardy, "High Temperature Expansion and Ru_pl;ure Behavior of

Z i r ca loy Tubing," Topica l 'Meeting of Water-Reactor S a f e t y , S a l t Lake

C i ty , Utah, CONF, -730304, ppI 254-271, March 27-28, 1973.

(12 ) K. M. Rose and E. D. Hikidle, "The Deformation of Zircaloy-2 Fuel

Cladding Under Loss-of-Coolant Accident T rans i en t s , " BNES I n t e r n a t i o n a l

Conference, London, Paper No. 83, October. 15-19, 1973.

'TABLE: I. LIST OF SINGLE-TEST H I G H TEMPERATURE TEST DATA

Specimen ue

( p s i ) Specimen

NI~~TES: 1 - Specimn p re s su r i zed a t room temperature and heated a t 1 6 O ~ / s e c t o t e s t ' temperature.

. 2 - A t i n d i c a t e s t ime t e l d at t h e - i so thermal t e s t temperature.

3 - Specimsns evacuated at t h e end of A t and cooled t o room temperature f o r measurement.

"SRA t e s t specimens ""Temperature "spike" t e s t specinens

TPBLE 11. INITIAL ?REDICTION MODEL PROPERTY FIT C(Xf3TANTS

NOTE: Values at 1475O~ and 1 6 5 0 ' ~ a r e based upon t h e equil ibr ium s t r u c t u r e isot.nermal t e s t data of Reference ( 1). Highsr t enperature values' &re based upon t h e singleit .est- specimen data presented i n t h i s report..

Temperature ( O F )

1475

1000

1700

1800

1900

2000

Intercep; S t r a i n Constants

A

2.753 x 10-I$

1.561 x 10-l~

0

0

3

3

St eady-St at e S t r a i n . Rate Constants

K

8,. 701 x

7.187 x lc.-lo

9.551 x lo-'

5.824 x lo-1o

3.757 x

2.170 x 10- l8

B

3.2660

1. 4948

1

1

1

1

n

4.9162

1.6193

1.4933

2.0306

2.9567

5.5258

C

0

0

4.653 x

6.644 x -.

6.948 x -

6.036 x

D

lo-6

lo-6

7.29 x 10 - L

7.701 x

1.008 x

1.997 x

TABLE 111. RESULTS OF ADDITIONAL TESTS AT 850°C

Specimen ~ o u p s t r e s s ( p s i ) Hoop S t r a i n ( % )

TBLE I V . FINAL PREDICTION MCIDEL PROPERTY FIT CONSTA3TS

NOTE: Values a t 1 4 7 5 ' ~ ar? baseel u p o ~ t h e equilfbr ium s t r u c t u r e isot:i?rmal slest da ta of Reference (1). Values a t 1700CF an3 h igher al-e based upon t h e s ingle- test-spezinen d a t a presented i n t h i s r e p o r t . Values a t 1530CF a r e t a k n t o b e t h e same as those a t 1700°F i n o rde r t o conservat ively p red ic t t h e Reference ( 8 ) t e s t h c a at 1 5 6 2 O ~ ( 8 5 0 ~ ~ ) .

Temperature ( O F )

1475

1503

1703

18013

1900

2000 -

I n t e r c s p t S t r a i n Constants Steady-State S t r a i n

Rate Constants

K

8.701 x

8 . 5 5 1 ~ 1 0 - ~

8 . 5 5 1 x 1 0 - ~

6 . 8 2 4 x 1 0 - ~ O ,

3.757 x

2.170 X ~ O - l8

10

Loq6

7 . 2 9 ~ 1 0 - ~

7.29 x

7 . 7 0 1 ~ 1 0 - ~

'1.008 x

1 . 9 9 7 ~ 1 0 - ~

A

2.753 x lc -lb

o

0

o

o

o

n

4.9162

1.4933

1.4933

2.0306

2.9 56'1

5.5256

3

3.265,)

1

1

1

1

-

C

O

3.653 x

5.653

6 .6b4 x

6.948 x

6.036 x

PRESSURE V A C \ U r U M P GAGE

MANnMFTFR

D SURFACE THERMOCOUPLE (OUTSIDE OF TEST SPECIMEN)

INNER THERMOCOUPLES NO. I

NO. 2

I I GASKET

SYSTEM PRESSURE I EXHAUST TRANSDUCER I

\GASKET IX) VALVE

Figure 1. Schematic of Test Apparatus

I I I I I

REFERENCE I TEST DATA AND PREDICTION MODEL

- -

C.

-

-

-

-

0 0 I 2 3 4 5 6

PREDICTED HOOP STRAIN.-%

Figure 2. Comparison of Isothermal P red ic t ions t o Measured U a t a

Figure 3.. LlOCA Temperature Transient Simulations

3 2 0 0

2 800

, 2 4 0 0

. . L L ' . 0

2 . 2 0 0 0

' a

I I I I I I 1 I

TMnx HOOP STRESS MEASURED HOOP PREDICTED HOOP-STRAIN - SPECIMEN OF - (PSI) STRAIN (9'0) USING REF I MODEL (9'0) -

9 3 - 8 , 1880 5 0 0 3.57 1.54 4 3 - 2 ,1650 500 0.46 ' 0 .39 9 3 - 2 1480 , 2 5 0 0 0.35 0.50 - -

- - 93-8

400

a -

I W I-

- . .

-

I

TIME -SECONDS

' 4 0 0 - -

0 I I 1 1 I I I 1 I

0 4 0 8 0 120 160 2 0 0 ' 2 4 0 280 ' 3 2 0 3 6 0

16OO0F u, = 750 PSI

Figure 4. Effec t 05 Test Procedure Upon S t r a i n Accumulation (lfhCf'3' - 750 p s i Hoop St ress . )

18OO0F , u, = 5 0 0 PSI

0 40 80. 120 160 200 240 280 320 T I M E AT ISOTHERMAL T E S T TEMPERATURE - SEC

4 .0

3.6

3.2

Figure 5 . . E f f e c t of Test Procedure Upon S t ra in Accumulation (1800 '~ - 500 p s i Hoop s t r e s s )

1 1 . . I 1 I I .

.SYM - ' SPECIMEN HEATUP EOUIL. TIME PRESS. DURING HEATUP MULTI-TEST

0 93 - 3 SLOW "9 MIN N 0 YES

- 0 2 0 -8 SLOW 2-1/2 MIN NO YES - 0. 4.3 - 3 IG°F/SEC 3 0 SEC I ST POINT ONLY YES

0 1 8 - 4 IG°F/SEC NONE I ST POINT ONLY YES

- A 7 7 - 3 / 4 4 - 2 IG°F/SEC NONE YES NO 3 -

-

-

-

-

- ISOTHERMAL T E S T DATA

-

-

' 4

1

2O0O0F c, = 500 PSI

7 I 1 1 I I I 1 I I I -

-

PRESS DURING MULTI- - - - SYM SPECIMEN HEATUP EQUIL. TIME HEATUP TEST a

YES IST POINT ONLY YES

A 77-8/ 18-7 IG°F/SEC NONE YES NO -

-

-

REFERENCE I - ' ISOTHERMAL T,EST DATA

0 I 1 1 1 I I I 1 1 I

0 10 20 ' 3 0 4 0 5 0 6 0 73 80 9 0 i00 110 TlME AT ISOTHERMAL TEST TEMPERATURE -SEC

F i g u r e 6 . Ef fec t oqf Test 7rocedure Upon S t r a i n A.:cunuBation ( 2 0 3 0 ~ ~ - 500 p s i Hoop s t r e s s )

NOTE: NEW SINGLE-TEST SPECIMEN DATA SHOWN WlTH CLOSED SYMBOLS - F?EE t MULTI-TE-ST SPECIMEN DATA SHOWN WITH OPEN SYMBOLS - -

-

I 6 R E F 9 DATA - -

- 9 REF 10 DATA 1475OF - ,

- - -

--9 -

- - /-

. . - -r- -

r-- 1 600° F 1 700° F

P - ' IY 7

- - -

1 900° F 20000 F -

- ---4 - - /

0 A2O0O0 F -

- / - ' 0' - d' d'dO'

-

I 1 1 1 I I I I I 1 I I 'I I l : l I I I I 2 4 6 81@ 2 4 6 . 8 1 0 - ~ 2 4 6 8 2 4

STEADY-STATE HOOP STRAIN RATE-I/SEC

Figure 7. Comparison of Steady-State S t r a i n Rate

1 1 I 1 . I I I A CURRENT TEST i( REF I -

-

REF 8 - TENSILE TEST IN INERT ATMOSPHERE - CO = 4.2 X INIINISEC -

-

-

-

-

-

- L

J I 1 I 1 I I I 0 7 50 800 850 900 950 10120 1050 1 100 1150

TEMPERATURE - O C

Figure 8. S t r a i n Fate S e n s i t i v i t y ' l a r i a t i cn with Temperature

I 1 I I I l l ] I I I I 1 1 1 1 - - - - 2000° F PREDICTION MODEL - -

- -

MODEL SHOWN FOR COMPARISON .

SYMBOL TEMP (OF) DATA SOURCE

- 2 0 0 0 NEW SINGLE-TEST DATA 1900 NEW SINGLE-TEST DATA ' ,

.O 1000 NEW SINGLE-TEST DATA A 1700 NEW SINGLE-TEST DATA - O 1600 NEW SINGLE-TEST DATA

-

% 2 0 0 0 REFERENCE ( I ) DATA 1800 - d

REFERENCE ( I ) DATA 1600 REFERENCE ( I ) DATA -

I 1 I I J.....l 1 1 I 1 I I l l

2 4 6 8 lo3 2 4 6 8 l o 4 HOOP STRESS, u8-PSI

Figure 9. Comparison o f I n t e r c e p t Hoop S t r a i n i n t h e n + R and B Regions .

I I I I I I I . .

0 1 6 0 0 ° F A 17OO0F

- 0 1 8 0 0 ° F -

0 2.000" F X LOCA T R A N S l E N T

-

-

- -

NOTE: I .. CLOSED SYMBOLS INDICATE PRE- .

T E S T TEMPERATURE SPl KE SPECEMENS -

2. FLAGGED 'SYMOLS ' INDICATE SRA TEST SPECIMENS

I I

0 I 2 3 4, 5 6 . 7 8 PRED'ICTED HOOP ST.RAIN - Yo

F i w r e 1 0 . Comparison of Predic ted and Measured S t r a i n

HEATING RATE. OF 25OC/SEC (45OF/SEC)

Figure 11. 'Comparison of P red ic t ions t o t h e Reference (11) Data

2

10'2

I I I 1 I I I I I I

u8 = 805 PSI . 08 .= 1127 PSI - .

-

- .

0 0 1

PEAK TEMPERATURE -OF

8

6

- - - - -

- - - -

- -

-

- - - - -

a -

a 4 - + - LJ . - I

- a

-

-

- -,

6 - - -

- - 4 - 0 -

- (1

-

2 - - 0.

10-1 L - . I . I 1. 1 A I I 1 I 1800 2000 2200 1600 I800 2 0 0 0

HEATING RATE OF 2 5 OC/SEC(45 OF/SEC)

Figure 12. Comparison of Predictions to the Reference (11) Data

- 2 1 I 1 1 I

PEAK TEMPERATURE -OF

l o 2 8

6

4

o\'

u8 = 1610 PSI . 0

00 = 2415 PSI

- ' 0 0

- - -

- - - -

- - - - - - -

2 - m

- rv. .

- - - - - - -

W - a -

' I 8 -- - - - -

6 - -

- -

4 - 0

- 0

- - -

2 - 0

- 0

10-1 - 1 I I I A I I I I 1 *

1600 1800 2000 1600 1800 2 0 0 0

HEATING RATE OF 25 "C/SEC (45 OF/SEC)

Figure 13. Cornpa-isan s f Pi-edict ions t o the Reference (11) Data

300 ,SEC. , ISOTHERMAL, CONSTANT-STRESS DATA OF REFERENCE (121

HOOP STRESS - PSI 0 2 0 0 4 0 0 - 600

HOOP STRESS 9 PSI

Figure 1 4 . Comparison of Predic ted and Measured Diametral S t r a i n

) . TUBE FURNACE WALL I

1 < 0.1 IN. DIA CERAMIC SUPPORT AND INSULATOR' THERMOCOUPLE WIRED TO' RECORDER '

THERMOCOUPLE 2-1/2 IN.

I 1 ; PRESSURIZING STEM (SEALED)

t 518 IN. VYCOR TUBE' SPECIMEN WIRED TO CERAMIC SUPPORT

Figure 15. Schematic of Test Apparatus

I 2 3 4 5 6 7 8 9 10 TIME- MINUTES

1 I I 1 1 I 1 1 I

- I_

5 M IN. ISOTHERMAL TEST 1 -

- START OF a -t 0 TRANSFORMATION -

-

SRECIMEN 6 2 - 9 ' - cro = 1000 PSI

- -

1 I I I I I I 1 ,

Figure 16. T y p i c a l Test Temperature Hist.ory

300 SECOND ISOTHERMAL TESTS AT 8 5 0 OC (1562OF)

I 0 2 8

6

4

2

10' 8

$ 6 2 z - 4 s I- a. a 8 2 I

loo 8

.6

4

2

10-1 0'

- I I I I - - . -

- - SYMBOL TEST ATMOSPHERE DATA SOURCE - - - 0 VACUUM REFERENCE (I2 1 - - A STEAM REFERENCE ( 12 1 - - n . . INERT-ARGON PRESENT TESTS -

- - 0'

/

- ~, - -

-

- -

PREDICTION - - /" MODEL USING '

- - - - 'A 1700°F PROPERTY

'a. FIT CONSTANTS -

. / 'A (TABLE IP) -

- 0 -

rn - - - w - -

- -

- -

- MODEL USING - TABLE Il PROPERTY -

- FIT CONSTANTS -

- -

1.- 1 1 . 500 1000 1500 2000 2 5 0 0

HOOP STRESS - PSI *U.S. GOVERNMENT PRINTING OFFICE: 1978-703-115/352

Figure 17. Comparison of Test Data and

P red ic t ion Models