investigation modeling degradation zr-based ......b. steps of the project 18th symp. zr in nuclear...
TRANSCRIPT
INVESTIGATION AND MODELING OF THE
DEGRADATION OF ZR-BASED FUEL
CLADDINGS DURING CORROSION IN STEAM
AND AIR-STEAM MIXTURES AT HIGH
TEMPERATURES
FLORIAN HAURAIS, [email protected]
ÉMILIE BEUZET,
MARTIN STEINBRÜCK,
ÉRIC SIMONI,
ANTOINE AMBARD,
MOHAMED TORKHANI
18TH SYMPOSIUM ON THE ZIRCONIUM IN THE NUCLEAR INDUSTRY
15-19 / 05 / 2016
OUTLINE
1. INTRODUCTION
2. EXPERIMENTAL PROTOCOL AND MATRIX
3. RESULTS FROM CORROSION TESTS
4. RESULTS FROM POROSIMETRIES
5. ANALYSIS AND MODELING
6. CONCLUSIONS AND PERSPECTIVES
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1. INTRODUCTION
A. FRAMEWORK
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PhD thesis in the research project of EDF R&D about SA in PWR: MAGESTIC
Reference simulation code for overall SA sequences: MAAP
Oxidation model of Zr-based claddings: mass gain correlations
Good prediction of reaction kinetics (C-U in steam, NUREG in air)
Quid in case of gas mixtures?
No information about the cladding mechanical degradation
Quid in case of oxide cracking or air ingress or core reflooding?
Enhancement of the H2 release during reflooding for some QUENCH tests:
H2 releases (g) during QUENCH-16 Before reflood During reflood
From Zr-based claddings (by metallography) 9 81
From the shroud and rods (by metallography) 4 43
From all (by mass spectrometry) 16 128
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1. INTRODUCTION
B. STEPS OF THE PROJECT
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1
• Study the behavior (reaction, degradation) of Zr-based claddings in
SA conditions (high T°, steam, air-steam, water reflooding)
2
• Define / perform / analyze experimental tests on Zr-based claddings
in SA conditions (at KIT through a partnership with EDF)
3
• Improve the cladding corrosion model in MAAP by considering its
mechanical degradation, to better predict the H2 production
• Validate these improvements against semi-integral experiments (e.g.
QUENCH tests) and overall scenarios (e.g. TMI-2)
OUTLINE
1. INTRODUCTION
2. EXPERIMENTAL PROTOCOL AND MATRIX
3. RESULTS FROM CORROSION TESTS
4. RESULTS FROM POROSIMETRIES
5. ANALYSIS AND MODELING
6. CONCLUSIONS AND PERSPECTIVES
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2. EXPERIMENTAL PROTOCOL AND MATRIX
A. PHENOMENOLOGY
Under pure steam In air-steam mixtures
< 1300 K > 1300 K < 1300 K > 1300 K
Reaction
kinetics
Parabolic-cubic
’Breakaway’
Linear
Parabolic
Parabolic
’Breakaway’
Linear-accelerated
Parabolic-linear
Degradation
mechanisms
Stress relieving
Cracking X
Stress relieving +
Nitriding process
Massive cracking
Nitriding process
Cracking
Zirconia layers Porous Dense Highly porous Porous
This open porosity: Represents the degradation state of samples
Can be measured by experimental methods
Tests at KIT-IAM: 1) Corrosion experiments plus 2) Porosimetry measurements
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1) Isothermal corrosion tests with two online measurements:
Mass gain of the sample by using a thermo-balance
Chemical composition of the outlet gas by using a mass spectrometer
2) Porosimetry by Hg intrusion with a twofold PASCAL apparatus:
PASCAL 140: up to 350 kPa ( pores down to 4 µm)
PASCAL 440: up to 400 MPa ( pores down to 4 nm)
Determination of sample volume, density and porosity (vol%)
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2. EXPERIMENTAL PROTOCOL AND MATRIX
B. PROTOCOL
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1 Zirconium alloy: ZIRLOTM cladding samples: 1cm-long open cylinders
2 corrosive atmospheres: Pure steam
50-50mol% air-steam mixture
8 constant temperatures (K):
1100, 1150, 1200, 1250, 1300, 1350, 1450, 1500
2 or 3 specific durations:
3 in case of ‘breakaway’ 1 in the parabolic kinetics
1 right after the ‘breakaway’
1 a longer time after it
2 otherwise 1 around 5 wt%
1 around 15 wt%
2 corrosion tests per condition to assess the reproducibility of porosimetries
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2. EXPERIMENTAL PROTOCOL AND MATRIX
C. TEST MATRIX
18th Symp. Zr in Nuclear Industry - 15-19 / 05 / 2016
OUTLINE
1. INTRODUCTION
2. EXPERIMENTAL PROTOCOL AND MATRIX
3. RESULTS FROM CORROSION TESTS
4. RESULTS FROM POROSIMETRIES
5. ANALYSIS AND MODELING
6. CONCLUSIONS AND PERSPECTIVES
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3. RESULTS FROM CORROSION TESTS
A. ZIRLOTM CLADDINGS UNDER STEAM
Consequences: Material alteration + H2(g) production + Heat generation
1100, 1150, 1300, 1350, 1450, 1500 K : Dense ZrO2, parabolic oxidation (n ~ 2.2)
1200 and 1250 K : Cracked ZrO2, oxidation parab.-cub. (n ~ 2.6) linear (n ~ 1.3)
)(.2)()(.2)( 22
.600
2
1
gHsZrOgOHsZr molkJH
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SMG = fct (T) * t 1/n
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3. RESULTS FROM CORROSION TESTS
B. ZIRLOTM CLADDINGS IN AIR-STEAM MIX
In addition to steam consequences: Material alteration + Heat generation
1350, 1450, 1500 K : Cracked zirconia layers, linear oxidation (n ~ 1.1)
Below 1350 K : Cracked zirconia layers, oxidation parab. (n ~ 2.3) linear (n ~ 0.8)
)()()( 2
.1100
2
1
sZrOgOsZr molkJ
)()()(1.370
221 sZrNgNsZr molkJ
)()()()( 221
2
.730
2
1
gNsZrOgOsZrN molkJ
1350 K 1350 K
Pure steam
50-50mol% air-steam mix
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1150 K 1150 K
OUTLINE
1. INTRODUCTION
2. EXPERIMENTAL PROTOCOL AND MATRIX
3. RESULTS FROM CORROSION TESTS
4. RESULTS FROM POROSIMETRIES
5. ANALYSIS AND MODELING
6. CONCLUSIONS AND PERSPECTIVES
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Air-steam mix: Significant porosity (> 4 vol%) for all T°
Pure steam: Significant porosity (> 4 vol%) at 1200 and 1250 K, with ‘breakaway’
Negligible porosity (< 2 vol%) at other T°, without ‘breakaway’
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4. RESULTS FROM POROSIMETRIES
A. INFLUENCE OF OXIDIZING CONDITIONS
The variability of porosity
results is due to:
- Measurement uncertainties
(~1 vol% absolutely)
- Variability of corrosion tests,
especially in case of ‘breakaway’
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‘breakaway’
no ‘breakaway’
Pure steam: porosity higher after (~ 5 vol%) than before (~ 2 vol%) the ‘breakaway’
Air-steam mix: porosity increases (> +2 vol%) during the ‘breakaway’
especially at 1250 K: +7 vol%
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4. RESULTS FROM POROSIMETRIES
B. IMPACT OF ‘BREAKAWAY’ (1/2)
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AFTER ‘breakaway’
BEFORE ‘breakaway’
BEFORE: pores > 4 μm = only a few macrocracks (~ 2 mm3/g)
AFTER: pores > 4 μm = macrocracks (~ 2 mm3/g, formed before ‘breakaway’)
+ pores < 4 μm = microcracks (~ 7 mm3/g, formed during ‘breakaway’)
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4. RESULTS FROM POROSIMETRIES
B. IMPACT OF ‘BREAKAWAY’ (2/2)
air-steam - 1200 K
BEFORE ‘breakaway’
air-steam - 1200 K
AFTER ‘breakaway’
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Higher porosity after ‘breakaway’ than before and in air-steam than in pure steam
Porosity evolution similar at 1200 and 1250 K
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4. RESULTS FROM POROSIMETRIES
C. EVOLUTION OVER TIME
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AFTER
‘breakaway’
BEFORE
‘breakaway’
OUTLINE
1. INTRODUCTION
2. EXPERIMENTAL PROTOCOL AND MATRIX
3. RESULTS FROM CORROSION TESTS
4. RESULTS FROM POROSIMETRIES
5. ANALYSIS AND MODELING
6. CONCLUSIONS AND PERSPECTIVES
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5. ANALYSIS AND MODELING
A. POROSITY INCREASE RATES (1/2)
Under pure steam:
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Only the 2 temperatures with ‘breakaway’ and significant porosity data, 1200 and 1250 K,
will be considered as inducing porosity.
Linear regressions Coefficient ~ 0.024 (vol% / (g.m-2)) between 1175 and 1275 K
T (K) 0 ↑
Steam dP/dt = 0
dP/dt =
0.024 *
dM/dt
dP/dt = 0
Air-steam dP/dt = 0.032 * dM/dt
dP/dt =
0.019 *
dM/dt
dP/dt =
0.019 *
dM/dt
dP/dt =
0.042 *
dM/dt
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dP/dt (vol%.s-1) = Coefficient * dM/dt (g.m-2s.-1)
Caption:
Darker areas: ‘breakaway’ phenomena occur
Hatched areas: zirconia cracking occur
1175 1275 1325 1400
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5. ANALYSIS AND MODELING
A. POROSITY INCREASE RATES (2/2)
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5. ANALYSIS AND MODELING
B. TRANSIENT TESTS FOR COMPARISON
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Zirconium alloy: ZIRLOTM cladding samples: 1cm-long open cylinders
Corrosive atmospheres: Pure steam and 50-50mol% air-steam mixture
Temperature range: 1100 K 1500 K
Heating rates (K.min-1): 50, 20, 10 Corrosion durations (min): 8, 20, 40
2 tests per condition to assess the reproducibility
Porosity (vol%) vs. heating rate (K.min-1)
(Triangles: simulations – Dashes: measurements)
Steam:
good qualitative agreement but negligible values (< 2 vol%)
Air-steam:
50-20 K.min-1: negligible measurements (< 2 vol%)
10 K.min-1: measurements (6 vol%) < simulations (10 vol%)
OUTLINE
1. INTRODUCTION
2. EXPERIMENTAL PROTOCOL AND MATRIX
3. RESULTS FROM CORROSION TESTS
4. RESULTS FROM POROSIMETRIES
5. ANALYSIS AND MODELING
6. CONCLUSIONS AND PERSPECTIVES
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The ‘breakaway’ process and its consequences occur:
At 1200 and 1250 K under pure steam
At 1100, 1150, 1200, 1250 and 1300 K in the air-steam mix
The porosity of oxidized ZIRLOTM cladding samples:
Is higher when ‘breakaway’ occurred (especially at 1200 and 1250 K)
Becomes significantly higher if the atmosphere contains air (O2 + N2)
Seems to be proportional to the SMG, in all conditions
These porosity values (from porosimetry by Hg intrusion) are used to:
Define and implement porosity increase rates into the MAAP code
Simulate the cladding mechanical degradation during detrimental phenomena
Improve the prediction of the H2 production, especially during core reflooding
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6. CONCLUSIONS AND PERSPECTIVES
A. CONCLUSIONS
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6. CONCLUSIONS AND PERSPECTIVES
B. PERSPECTIVES
Experimental aspects
Additional oxidation tests and porosity measurements to extend conclusions
•Other Zr alloys (Zry-4 and/or M5)
•Other air-steam mixtures
•Several gas flow rates
•Higher temperatures (up to almost 1900 K)
Modeling aspects
Consideration of the temperature variation rate
Validation against semi-integral experiments (e.g. QUENCH tests)
Validation against overall scenarios (e.g. TMI-2)
18th Symp. Zr in Nuclear Industry - 15-19 / 05 / 2016