SiC/SiC composite behavior in LWR conditions and under high temperature steam environment

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HAL Id: cea-02509729

https://hal-cea.archives-ouvertes.fr/cea-02509729

Submitted on 17 Mar 2020

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C. Lorrette, C. Sauder, P. Billaud, C. Hossepied, G. Loupias, J. Braun, A.

Michaux, E. Torres, F. Rebillat, J. Bischoff, et al.

To cite this version:

C. Lorrette, C. Sauder, P. Billaud, C. Hossepied, G. Loupias, et al.. SiC/SiC composite behavior in LWR conditions and under high temperature steam environment. TOP FUEL Reactor Fuel Perfor-mance 2015, Sep 2015, Zurich, Switzerland. �cea-02509729�

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13-17 SEPTEMBRE 2015

TOP FUEL Reactor Fuel Performance |Zurich, Switzerland

HIGH TEMPERATURE STEAM ENVIRONMENT

C. LORRETTE*, C. SAUDER, P. BILLAUD, C. HOSSEPIED, G. LOUPIAS, J. BRAUN, A. MICHAUX

E. TORRES, F. REBILLAT

LCTS, UMR CNRS-UB1-SPS-CEA, F-33600 Pessac, France CEA, DEN, DMN, F-91191 Gif-sur-Yvette, France

*christophe.lorrette@cea.fr

J. BISCHOFF AREVA NP, F-69456 Lyon, France

A. AMBARD

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A Decade of R&D activity at CEA has been dedicated to the development of

SiC/SiC composites for GFR fuel cladding application: 2005-2015

Focus on metal/ceramic hybrid cladding: a solution to leak-tighness

P a te n t W O 2 0 1 3 /0 1 7 6 2 1 A 1

The potential benefits in terms of application temperature and dimensional

stability make this concept have a very high potential for EATF

Inner and outer SiC/SiC layers

Middle thin (50-100µm) metallic liner

Selected on various criteria – current reference is Ta (GFR) –

CEA « S

ANDWICH

»

CLADDING DESIGN

Transposition to LWR is under investigation with the current manufacturing process

Objectives for current research (French Nuclear Institute)

Assess the SiC resistance to corrosion/interaction with coolant in normal operating conditions Define the overall performance under high temperature steam

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EXPERIMENTAL

First oxidation tests in CEA autoclaves – Static and closed system

Representative LWR nominal conditions (360°C / 180 bar) up to 3500 h – 5 months 2 compositions of water

vs

Distilled water LWR water composition

1000 ppm H3BO3+ 2 ppm LiOH

pure

Materials examinated

T

UBULAR

S

I

C/S

I

C

COMPOSITES

(

WITHOUT LINER

)

Nuclear grade materials (from CEA)

Hi-Nicalon S fibers + CVI-SiC matrix

Multilayered 2D architectures (filament winding, braiding with 45°angle) Pyrocarbon interphase between fibers and matrix

Thickness 1 mm, ∅10 mm, L 75 mm

As-received and intentionally pre-damaged SiC/SiC at different level (0.05 to 0.5 % σσσσR)

Acess to PyC interphase allowed to oxidizing species

H

IGH PURITY

CVD-S

I

C

Monolithic rod samples

For understanding and comparison to CVI-SiC matrix

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-40 -20 0 20 40 60 S p e ci m e n w e ig h t ch a n g e ( m g /c m 2)

No visible effect of water chemistry Similar results between DW and LWR water

Greater weight loss for pre-damaged materials in comparison to undamaged

But not be quantifiable exactly due to uncertinity on exchange surface Water infiltrates through the larger crack openings and oxidizes the SiC materials from inside and not just on the surface

CORROSION RATE IS INCREASING

Surface crack openings

WEIGHT CHANGE

(LWR

RESULTS PRESENTED

)

Zr4

CVD-SiC

SiC/SiC composites

0.05% 0.15% 0.30% 0.50% Undamaged

Exchange surface area calculated by TOMO-X for composites

After 5 months of testing

Confirmation of weight loss for SiC-based samples in comparaison to weight gain for Zr

Zr4 SiC samples ~ 3-4 µm ZrO₂ growth Recession Thickness < 0.5 µm Pre-damaged

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KINETICS AND SURFACE ROUGHNESS

Results on CVD-SiC samples (representative of the CVI-SiC matrix)

-25 -20 -15 -10 -5 0 0 500 1000 1500 2000 2500 3000 3500 S p e c if ic w e ig h t c h a n g e ∆∆∆∆ m /S ( m g /d m 2)

Exposure time (Hours)

Terrani et al. 2014 [PWR 330°C (Autoclave)] This work [DW 360°C (Autoclave)]

0,5 µm

Slow kinetics of SiC recession which tends to stabilize at long time in static conditions (closed system) Before

RMS : 4,32 µm

After 3500 h

RMS : 4,53 µm

AFM IMAGES

Limited effect on surface specimen (Roughness) – No passivation layer (to be confirm)

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POST-EXPOSURE MECHANICAL TENSILE BEHAVIOR

No significant degradation of the mechanical behavior after long-term exposure

0 50 100 150 200 250 0,0 0,2 0,4 0,6 0,8 1,0 S tr e s s ( M P a ) Strain (%) REFERENCE DISTILLED WATER LWR UNDAMAGED COMPOSITES

Characteristic damageable behavior with a low fiber-matrix bonding after oxidation (DW and LWR)

0 50 100 150 200 250 0 0,5 1 1,5 S tr e s s ( M P a ) Strain (%) LWR UNDAMAGED LWR 0.15% LWR 0.3%

0.79 % / 231 MPa 0.88 % / 229 MPa 0.85 % / 216 MPa

PRE-DAMAGED COMPOSITES

Pyrocarbon interphase is not significantly degraded for these oxidation conditions Slight reduction of strength (5%) for pre-dammaged samples in comparaison to the reference

Fiber-matrix load transfer remains efficient to provide ability to deform for SiC/SiC

LWR 0.15% 0.85% / 216 MPa 0.88% / 229 MPa 0.79% / 231 MPa LWR 0.30% LWR UNDAMAGED

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POST-EXPOSURE THERMAL BEHAVIOR

Measured on undamaged SiC/SiC exposed in dynamic conditions (Loop, AREVA Facility)

Tube Config.B Config. A IR Caméra Flash impulsion

∑

∞ = − + = + 1 )] ² ² ² 4 exp( ) 1 ( 2 1 [ 2 ) , ( ) , 0 ( k k _at e k ce Q t e T t T π ρ ) ² ² )² 1 2 ( exp( 4 ) , ( ) , 0 ( 0 at e k ce Q t e T t T k

∑

∞ = + − = − π ρ 0 5 10 15 20 25 30 -10 10 30 50 70 90 110 130 150 Tr a n sv e rs e t h e rm a l co n d u ct iv it y ( W .m -1.K -1)

Exposure time (days)

ρ2823 kg.m-3_{/ Cp 680 J.kg}-1_.K-1 Transverse conductivity calculated from post-exposure

diffusivity measurments at RT

No effect of oxidation on the thermal behavior after 80 days

Consistent result with the thin sample recession and the surface analysis Next measurements after 300 et 500 days – no expected change…

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Evolution of surface composition on SiC/SiC tubes before and after exposure

DISCUSSION AND MECHANISM

LWR SiC 61,1 %at SiCxOy 22,4 %at

SiO2 16,4 %at

X-ray photoelectrion spectroscopy XPS (Si-2p)

After oxidation, presence of a larger (but low) quantity of SiO₂ oxide

DW SiC 69,6 %at SiCxOy 15,2 %at SiO2 15,2 %at SiC 76,6 %at SiCxOy 17,0 %at SiO2 6,4 %at REF

_4(aq)

+ CH

_4(g)

Probable mechanisms

DISCUSSION AND MECHANISM

In both cases, material is being consumed

Need further investigation to conclude on mechanism

(see Terrani et al., ICACC 2015 and others)

Go to the next step

Assessment of performances in accidental conditions

Positive mechanical/thermal behavior of SiC/SiC in LWR conditions (Out of pile)

P

ARTIAL CONCLUSIONS

:

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| PAGE 10

CEA | 10 AVRIL 2012

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Total Water PH2O/PT PO2/PT PO2/PH2O HP A 1200 10 0.5 Air 9.5 0,05 (5) 0,19 (19) 3,8 B 1200 1 0.5 O2 0.5 0,5 (50) 0,5 (50) 1 C 1200 1 0.5 Air 0.5 0,5 (50) 0,1 (10) 0,2 D 1400 1 0.5 Air 0.5 0,5 (50) 0,1 (10) 0,2 Patm

Conditions Temperature (°C) Pressure (bar)

Gas in addition

Pressure ratio (%)

Double sided oxidation exposure for 4 to 110h

Steam and air/O2 flow (5cm/s) with various oxygen content – Total pressure between 1 to 10 bar

Extremely slower oxidation kinetics of SiC/SiC than for Zr alloys !

Confirmation of high potential of SiC/SiC for ATF

Experiments on SiC/SiC tubes and Zircaloy-4 clad segments as baseline material

-200 0 200 400 600 800 1000 0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 S p e ci fi c w e ig h t ch a n g e Δ m /S ( g .m -2)

Exposure time (hours)

before exposure 4h 110h SiC/SiC composite Zy4 Zy4 SiC/SiC composite Zy4 (literature) CONDC 1bar, 1200_°C Air/H2O (50/50)

E

XPERIMENTAL

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F

OCUS ON

S

IC

/S

I

C

0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0 0 20 40 60 80 100 120 S p e c if ic w e ig h t ch a n g e Δ m / S ( g .m -2) Time (hours) P_O2/P_H2O 0,2 3,8 0,2 1 1400°C 1200°C

But volatilization of oxide is occuring from its formation (Opila et al. 97)

Oxidation kinetics are strongly dependent on the bondary conditions

Acceleration effect with temperature (1200 vs 1400°c)

Formation of protective oxide scale (silica)

SiC fibres SiC matrix

Silica (SiO₂)

SiO_2(s)

Global behavior resulting from the competition between

simultaneous growth and volatilization of a silica oxide

SiC_(s)

∆∆∆∆m/S

t(s) t * (v = cste)

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RESIDUAL MECHANICAL TENSILE BEHAVIOR

(RT)

Integrity and geometry of specimens fully preserved after 110h exposure

Confirmation of the protective function of silica in these conditions

Pyrocarbon interphase stays efficient to deviate cracks

Retention of the characteristic « non-linear elastic damageable » behavior of CMCs

(No reduction of strain to failure / Slight decrease of tensile strength and Young modulus)

0 50 100 150 200 250 300 350 400 450 500 0 0,2 0,4 0,6 S tr e ss ( M P a ) Strain (%) As-received

Influence of atmosphere

P_O2/P_H2O 3,8 0,2 1 1200°C 0 50 100 150 200 250 300 350 400 450 500 0 0,2 0,4 0,6 St re ss ( M P a ) Strain (%) As-received

Influence of temperature

1400°C 1200°C

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Suggested oxidation process

DISCUSSION AND MECHANISM

A

FTER OXIDATION Si_xO_yH_{z (g)} CO_(g)/CH_{4 (g)} H₂O_(g) SiC fiber PyC SiC SixOyHz (g) H2O(g) SiO₂oxide

″″″″Accelerated″″″″oxidation kinetics able to locally cause fibers bonding

at pre-existing surface cracks

O_2(g)

SiC

PASSIVATION/ SELF-HEALING

1400

_°

C – 110h

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Using SiC

_f

/SiC composites as fuel cladding element for LWRs

represents

a

considerable

challenge

to

ambitious

objectives (ATF)

SiC/SiC composites is a break-through solution

which requires a long term R&D

Although many progresses have been made, many prospects have been

raised to confirm the feasibility of using SiC/SiC for LWR

Technical update (present work)

Autoclave tests results in LWR nominal operating conditions are positive in term of mechanical and thermal behavior

… but highlight a different behaviour for SiC (recession) than conventional Zr High temperature strength in steam was demonstrated (up to 1400_°C, > 100h)

On going work and some pending issues

Transposition of sandwich clad to LWR requirements (design, most suitable liner) Manufacturing of elongated and closed clad – by welding for the « sandwich » design Evaluation of neutron irradiation

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christophe.lorrette@cea.fr

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