17th International Symposium on Zirconium in the Nuclear Industry

The effect of Sn on corrosion mechanisms i d d Z l ddi f PWRin advanced Zr-cladding for PWR

Philipp Frankel, J. Wei, E. Francis, S. Lyon, R.A. Cottis, M. PreussMaterials Performance Centre, The University of Manchester

N Ni S L P C R M GN. Ni, S. Lozano-Perez, C. R. M. GrovenorDepartment of Materials, University of Oxford

R. J. Comstock, L. HallstadiusWestinghouse, USA/SwedenA. Ambard, M. Blat-Yrieix

EDF FranceEDF, France

03-08 February, Hyderabad, India

Oxi

datio

n of

Zr

Allo

ysyWhat w

e know

:

Large compressive stress in oxide

gp

Zr to

 ZrO

2transformation ‐volum

e increase

Tw

ooxideph

ases:M

onoclinic,Tetragonal

Two oxide ph

ases: M

onoclinic, Tetragonal

Tetragon

al only stable at 3

60C by stress, grain size (or chem

istry)

Transformation Tet

mon

o, fu

rthe

r volume increase

Gll

Tlh

if

Gen

erally, m

ore Tetragon

al phase near interface

Recent work (M

UZIC program):

Level of transform

ation im

portant to transitio

n

Related to nano‐po

rosity in

 oxide

1A

STM

Intl,

Vol

. 8, N

o. 9

, doi

: 10:

1520

/JA

I103

246,

201

1, 6

49-6

812

Jour

nal o

f Nuc

lear

Mat

eria

ls 4

32 (2

013)

, pp.

102

-112

3ActaMateralia, 2013

The

effe

ct o

f Sn:

Del

ayed

tran

sitio

ny

ZIR

LO®

Exp

erim

enta

l Z

IRLO

®E

xper

imen

tal

allo

y

~0.

92 w

t% S

n~

0.01

wt%

Sn

0.92

wt%

Sn

Exp

osur

e at

360

C in

Wat

er (

Day

s)E

xpos

ure

at 3

60C

in W

ater

(D

ays)

Tabl

e 1:

Mea

sure

d ch

emic

al c

ompo

sitio

n of

the

mat

eria

ls.

Allo

y Al

loyi

ng E

lem

ents

Zr

Fe

[wt%

] Sn

[wt%

] N

b[w

t%]

Hyd

roge

n [w

t.ppm

] ZI

RLO

®ba

lanc

e0

090

920

9110

p(

y)

ZIR

LO

bala

nce

0.09

0.92

0.91

10

A-0.

0%Sn

ba

lanc

e 0.

1 0.

01

1.00

17

 

Syn

chro

tron

X-R

ay D

iffra

ctio

ny

y

ZIR

LO®

A0

0%S

n

Evolution of Residual stress and ph

ase fractio

n

ZIR

LO®

A-0

.0%

Sn

Ex-

situ

XR

DE

x-si

tu X

RD

Ex

situ

XR

DE

xsi

tu X

RD

Exp

osur

e at

360

C in

Wat

er (

Day

s)E

xpos

ure

at 3

60C

in W

ater

(D

ays)

p(

y)

Measure sam

ples after different len

gths of autoclave exposure

Syn

chro

tron

XR

D: P

enet

ratio

n de

pth

H

igh-

ener

gy a

nd h

igh

flux

S

uffic

ient

pen

etra

tion

to s

ampl

e en

tire

oxid

e as

oxi

de th

icke

nsp

p

Labo

rato

ry X

RD

Syn

chro

tron

XR

D

Thin

oxi

deM

tl

(~ 3

µm)

Met

al

Thic

ker o

xide

Syn

chro

tron

XR

D:

H

igh-

ener

gy a

nd h

igh

flux

S

uffic

ient

pen

etra

tion

to s

ampl

e en

tire

oxid

e as

oxi

de th

icke

nsp

p

Fast

cou

ntin

g tim

es

G

ood

sign

al, l

ow b

ackg

roun

dP

hf

ti

Pha

se fr

actio

n

Res

idua

l Stre

ss M

onoc

linic

& T

etra

gona

l pha

ses

Syn

chro

tron

XR

D R

esul

ts: E

ffect

of S

ny

Te

trago

nal P

hase

Fra

ctio

n

ZIR

LOA

-0.0

%S

n

Oxi

deO

idO

xide

Met

alM

etal

Oxi

de

Met

alM

etal

Oxi

de

The

effe

ct o

f Sn:

Res

idua

l stre

ssZ

IRLO

A-0

.0%

Sn

Mon

oclin

ic

Tet

rago

nal

The

effe

ct o

f Sn:

Res

idua

l stre

ssZ

IRLO

A-0

.0%

Sn

Mon

oclin

ic

Not

str

ess

stab

ilise

do

ses

ss

abse

d

Tet

rago

nal

Ex-

situ

syn

chro

tron

XR

DI

id

b

ZIR

LO®

Allo

y

Interesting tren

ds, but…

ZIR

LO®

Allo

y A

Ex-

situ

XR

DE

x-si

tu X

RD

Ex

situ

XR

DE

xsi

tu X

RD

Exp

osur

e at

360

C in

Wat

er (

Day

s)E

xpos

ure

at 3

60C

in W

ater

(D

ays)

p(

y)

Only few points, different sam

ples 

relatively high

 scatter

No inform

ation from

 early in

 corrosion

In-S

itu E

xper

imen

t

Sample he

ated

 in air at 5

50C during XR

D

Fast eno

ugh grow

th fo

r 12 ho

ur experim

ent

Nid

li

i?

Not ideal com

parison to ex‐situ m

easuremen

ts?

Manydata

pointsfrom

singlepo

into

nsinglesample!

Many data points from

 single po

into

n singlesample!

ZIRLO

Hihiii

llh

d

ihi

Tet

rago

nal p

hase

evo

lutio

n at

550

C

ZIRLO: H

igh initial te

tragon

al phase 

redu

ces with

 time 

tion ase fract nal pha Tetrago T

Oxi

datio

n tim

e at

550

C

Tet

rago

nal p

hase

evo

lutio

n at

550

C

Hihiii

llh

d

ihi

Lower te

tragon

al con

tent fo

r A‐0%Sn

High initial te

tragon

al phase 

redu

ces with

 time 

tion ase fract nal pha Tetrago T

Oxi

datio

n tim

e at

550

C

Tet

rago

nal p

hase

evo

lutio

n at

550

C

Plb

df

A0%

S

Plateau ob

served

 for A

‐0%Sn

tion ase fract nal pha Tetrago T

Oxi

datio

n tim

e at

550

C

Effe

ct o

f red

uced

Sn

Lower te

t. pha

seA

ihE

ib

if

360C

Agrees with

 Ex‐situ observatio

n for 3

60C

Sn

stabilises tetragon

al phase in

 engineering

 ceram

ics

Plateau with prolon

ged oxidation

Agrees with

 Ex‐situ observatio

n for 3

60C

g

Tet. phase uniform

ly distributed

, i.e. not stress stabilised

Hihiitilt

th

didl

High initial tet. p

hase, red

uces ra

pidly

Not observed previously!!!

Tilti

tibl

itTime resolutio

n no

t possible ex‐situ

Mon

oclin

ic r

esid

ual s

tres

s at

550

C

Co

nstant m

onoclinic stress for ZIRLO

Mon

oclin

ic r

esid

ual s

tres

sLower Snalloy –lower stresses that re

lax over time

Re

duced creep strength (impo

rtant b

enefit of Sn!)

pg

(p

)

Mon

oclin

ic r

esid

ual s

tres

sLower Snalloy –lower stresses that re

lax over time

Re

duced creep strength (impo

rtant b

enefit of Sn!)

pg

(p

)

Sh

arp

dro

p in

T

et F

ract

ion

Tet

. Fra

ctio

n

Ph

ase

tran

s?

Tet

rago

nal r

esid

ual s

tres

sg

ZIRLO –large compressive stress, som

e relaxatio

n

Lower te

tpeak intensity

 –larger scatter

Re

duced creep strength

Tet

rago

nal r

esid

ual s

tres

sg

A‐0%Sn

 –Lower com

pressive stress

Even

 lower te

tpeak intensity

 –Even

 larger scatter!

Tet

rago

nal r

esid

ual s

tres

sg

Stress canno

t be stabilising

 mechanism

With

 low Sn, only grain size stabilised

 tetragon

al present 

Not

stressstabilised

Not stress stabilised

Sum

mar

yy

O

bser

vatio

nsat

550

Cco

rrel

ates

wel

lwith

360

CO

bser

vatio

ns a

t 550

C c

orre

late

s w

ell w

ith 3

60C

S

imila

r mec

hani

sm d

espi

te d

iffer

ent e

nviro

nmen

t

R

educ

ed S

n

Low

er te

trago

nal p

hase

frac

tion

N

otst

ress

stab

ilise

d

Not

stre

ss s

tabi

lised

D

elay

ed tr

ansi

tion

with

redu

ced

Sn

R

elat

ed to

lack

of s

tress

sta

bilis

ed T

etra

gona

l

redu

ced

trans

form

atio

n

Pro

pose

d m

odel

Wha

t hap

pens

aro

und

trans

ition

?

Pre

-tra

nsiti

on:

Larg

er T

et g

rain

sLa

rger

Tet

. gra

ins,

Str

ess

stab

ilise

d

Gra

dual

tran

sfor

mat

ion

U

ncon

nect

ed N

ano

poro

sity

Wha

t hap

pens

aro

und

trans

ition

?

Pre

-tra

nsiti

on:

Larg

er T

et g

rain

sT

rans

ition

:R

apid

tran

sfor

mat

ion

Larg

er T

et. g

rain

s,S

tres

s st

abili

sed

Tra

nsfo

rmed

Rap

id tr

ansf

orm

atio

nLo

calis

edin

com

patib

ilitie

s

Lo

wer

str

ess

tr

ansf

orm

atio

n

Vo

lum

e in

crea

se

Gra

dual

tran

sfor

mat

ion

U

ncon

nect

ed N

ano

poro

sity

Wha

t hap

pens

aro

und

trans

ition

?

Pre

-tra

nsiti

on:

Larg

er T

et g

rain

sT

rans

ition

:R

apid

tran

sfor

mat

ion

Larg

er T

et. g

rain

s,S

tres

s st

abili

sed

Tra

nsfo

rmed

Rap

id tr

ansf

orm

atio

nLo

calis

edin

com

patib

ilitie

s

Lo

wer

str

ess

tr

ansf

orm

atio

n

Vo

lum

e in

crea

se

Gra

dual

tran

sfor

mat

ion

U

ncon

nect

ed N

ano

poro

sity

Rap

id tr

ansf

orm

atio

n

Inte

rcon

nect

ed p

oros

ityF

E c

ourt

esy

of P

. Pla

tt

Fur

ther

opt

ions

p

Low

er te

mpe

ratu

re o

xida

tion

S

low

er o

xida

tion

O

xida

tion

in s

team

A

pply

stea

mdu

ring

test

ing

A

pply

ste

am d

urin

g te

stin

g

H

igh

tem

ps. &

Tra

nsie

nts

~

LOC

A co

nditi

ons

Ali

dl

dd

iid

ti

App

lied

load

dur

ing

oxid

atio

n

Effe

ct o

n ox

idat

ion

rate

Ack

now

ledg

men

ts

g

MU

ZIC

par

tner

s:

ED

F, N

atio

nal N

ucle

ar L

abor

ator

y, R

olls

-Roy

ce, A

mec

and

,y,

y,

Wes

tingh

ouse

D

iam

ond

Ligh

t Sou

rce

I12

bli

I1

2 be

am li

ne

Eve

ryon

e th

at h

elpe

d on

Exp

erim

ent!

Fu

ndin

gg

Than

ks to

the

Eng

inee

ring

and

Phy

sica

l Sci

ence

Res

earc

h C

ounc

il (E

PS

RC

) and

MoD

in

the

UK

for f

undi

ng th

e re

sear

ch a

s pa

rt of

the

Mat

eria

ls fo

r Ene

rgy

call

(res

earc

h co

de:

EP

/E03

6171

/1).