Hydrogen Absorption Mechanism of Zirconium Alloys Based on
Transcript of Hydrogen Absorption Mechanism of Zirconium Alloys Based on
16th ASTM Zr Symposium, Chengdu, May 9-13, 2010 1
K. Une*1, K. Sakamoto1, M. Aomi1, J. Matsunaga1 , Y. Etoh1
I. Takagi2, S. Miyamura2, T. Kobayashi2, K. Ito3
1 Nippon Nuclear Fuel Development Co., Ltd.2 Kyoto University, Dept. Nuclear Eng.3 Global Nuclear Fuel Japan Co., Ltd.
Hydrogen Absorption Mechanismof Zirconium Alloys
Based on Characterization of Oxide Layer
16th ASTM Zr Symposium, Chengdu, May 9-13, 2010 2
●● SampleSample
●● Corrosion testCorrosion test- Steam at 400 °C- 1M LiOH aqueous solution at 290-350 °C
●● Characterization of oxide layerCharacterization of oxide layer- Microcrack(SEM/BSE)- Microstructure (TEM/STEM)- Alloy element precipitation/dissolution (SIMS mapping/EPMA)- Crystal structure/stress state (Raman spectroscopy)- In-situ hydrogen diffusivity (NRA)- Alloy element chemical state (XANES)
Alloy Sn Fe Cr NiZry-2 1.36 0.18 0.11 0.07GNF-Ziron 1.46 0.26 0.10 0.05VB 0.5 0.5 1.0 -
wt%
Experimental
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10
100
1000
0.1 1.0 10.0 100.0t (d)
Hyd
roge
n (p
pm)
Zry-2GNF-ZironVB
m=1
1 10 10010
100
1000
1 10 100 1000t (d)
Hyd
roge
n (p
pm)
Zry-2GNF-ZironVB
m=1/2
Hydrogen Absorption Ratein Out-of-pile Corrosion Tests
Hydrogen absorption rate- LiOH water test (linear law) >> Steam test (paraboric law)- Zry-2 > Ziron > VB
Steam test (400Steam test (400 °°CC )) LiOH test (290LiOH test (290 °°CC ))
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0
20
40
60
80
100
0 5 10 15t (d)
Hyd
roge
n pi
ckup
frac
tion
(%)
Zry-2GNF-ZironVB
0
20
40
60
80
100
0 20 40 60 80 100 120t (d)
Hyd
roge
n pi
ckup
frac
tion
(%) Zry-2
GNF-ZironVB
Zry-2>GNF-Ziron>VB
Hydrogen Pickup Fractionin Out-of-pile Corrosion Tests
Steam test (400Steam test (400 °°CC )) LiOH test (290LiOH test (290 °°CC ))
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Cross Sectional BSE Images of Oxide LayersZry-2 GNF-Ziron VB
1 mm
3 mm
1 mm 1 mm
1 mm 1 mm 1 mm
3 mm 3 mm
(a) (b) (c)
(d) (e) (f)
(g) (h) (i)
Steam oxideSteam oxide(Pre(Pre--transition)transition)
Steam oxideSteam oxide(Post(Post--transition)transition)
LiOH waterLiOH wateroxideoxide
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ZryZry--2 (1.62 (1.6 mmm)m) VB (1.1VB (1.1 mmm)m)
Cross Sectional TEM Imagesof LiOH-water Oxide at Metal/Oxide Interface
Oxide
Metal
Degraded grain boundaries
50 nm
(a) Oxide
Metal
Degraded grain boundaries
50 nm
(b)
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-12
-10
-8
-6
-4
-2
0
0.0001 0.001 0.01 0.1 1
LiOH濃度 (mol/l)Log
[X]
(mol
/l)
[OH-]
[H+]
[HZrO3-]
[Li+]
FT-IR Results and Thermodynamicsof ZrO2-LiOH-H2O System
Ion concentration in solution at 290Ion concentration in solution at 290 °°CC
LiOH concentration (mol/l)
Higher HZrO3- concentration
at higher LiOH solution(ZrO2 + OH- = HZrO3
-)
O-H bonds detected only in LiOH oxide
0.00
0.05
0.10
0.15
0.20
0.25
5001000150020002500300035004000
Wavenumber (cm-1)
Reflection (-)
H2O Oxide
LiOH Oxide
Zr-O
Zr-O
CO2
OH
Steam oxide
LiOH oxide
FTFT--IR spectra in oxide layerIR spectra in oxide layer
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Zry-2 (1.4 mm) VB (1.4 mm)
Cross Sectional TEM Images of Pre-transitionSteam Oxide at Metal/Oxide Interface
酸化膜
金属部
Oxide
Metal 200 nm
Precipitate
(a)
m/t-ZrO2
hcp-Zr
sub-oxideSub-oxide
A
B
C
A
B
C
酸化膜
金属部
Oxide
Metal 200 nm
Precipitate
(b)
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STEM/EDS Images of Pre-transition Steam Oxide
Sub-oxide layer
Sub-oxide layer
(a) (b) (c)
(d) (e) (f)
STEM Fe Cr
ZryZry--22
VBVB
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187
188
189
190
191
192
193
0.0 0.5 1.0 1.5 2.0Distance from M/O boundary (mm)
Wav
enum
ber (
cm-1
)
Zry-2GNF-ZironVBPowder sample
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.5 1.0 1.5 2.0Distance from M/O boundary (mm)
Tetra
gona
lZrO
2 fra
ctio
n
Zry-2GNF-ZironVB
Tetragonal ZrO2 Fraction and Raman Shiftin Steam Corroded Oxides
Tetragonal ZrO2 fraction near M/O boundaryVB > Ziron » Zry-2
Tetragonal ZrOTetragonal ZrO22 fractionfraction Raman shift of monoclinic ZrORaman shift of monoclinic ZrO22 peakpeak
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-2.0
-1.6
-1.2
-0.8
-0.4
0.0
0.0 0.5 1.0 1.5 2.0Distance from M/O boundary (mm)
Stre
ss (G
Pa)
Zry-2GNF-ZironVB
Compressive Stress in Steam Corroded Oxides
Compressive stress distributionCompressive stress distribution
Pressure dependencePressure dependenceof monoclinic ZrOof monoclinic ZrO22 peakpeak
J. Godlewski, et al., ASTM STP 1354, 2000, pp.877-900
Gruneisen coeff.Gruneisen coeff.2.5 cm2.5 cm--11/GPa/GPa
Compressive stress in inside oxide layerVB > Ziron > Zry-2
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Nuclear Reaction Analysis for DeuteriumDistribution in Oxide Layer
NRA: D(3He,p)4He
T/C
Deuteriumplasma
3He+ (1.7MeV)p
Zr alloy specimen
D2 gas
Oxide layer
SSD
W heater(Max. 400℃)
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0
5E+20
1E+21
1.5E+21
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0
Distance from oxide surface (mm)
Deu
teriu
m c
onc.
(cm
-3)
Zry-2GNF-ZironVB
Oxide layer(Zry-2)
(Ziron)(VB)
LiOD-water oxide (290°°C xC x 40h)) D2O-steam oxide (400 °C x 15d)
0
1E+20
2E+20
3E+20
4E+20
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0Distance from oxide surface (mm)
Deu
teriu
m c
onc.
(cm
-3)
Zry-2GNF-ZironVB
Non-protectivelayer
Barrier layer1at%
Deuterium Profiles in LiOD-waterand D2O-steam Oxides
・Double layer structureOutside: non-protective layer (0.8 mm)Inside: barrier layer (0.8-0.9 mm)
・Barrier layer widthAlmost no difference among the alloys
・Almost flat deuterium profile⇒Rate-controlling step: M/O boundary reaction
・Deuterium concentration in oxide layerZry-2 > Ziron > VB
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0
2E+20
4E+20
6E+20
8E+20
1E+21
-0.5 0.0 0.5 1.0 1.5 2.0Distance from oxide surface (mm)
Deu
teriu
m c
onc.
(cm
-3)
5700s11700s22500s26100s
Barrier layerNon-protectivelayer
0
2E+20
4E+20
6E+20
8E+20
1E+21
-0.5 0.0 0.5 1.0 1.5 2.0Distance from oxide surface (mm)
Deu
teriu
m c
onc.
(cm
-3)
4500s15300s29700s44100s
Barrier layerNon-protectivelayer
In-situ Deuterium Diffusion Profilesin H2O-Steam Oxide at 300 °C
VB oxide (1.4VB oxide (1.4 mm))
Diffusion coefficient in barrier oxide layerGNF-Ziron: D=3.8E-14cm2/s at 26100 sVB : D=1.7E-14cm2/s at 29700 s
GNFGNF--Ziron oxide (1.7Ziron oxide (1.7 mm))
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SIMS Mapping of Zry-2 LiOH-water Oxide
(d)
(c)
2mm
1
0.1
0.01
(b)
Metal
Oxide
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SIMS Mapping of Zry-2 Steam Oxide
2mm
Metal Oxide1
0.1
0.01
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SIMS Mapping of VB Steam Oxide
2mm
1
0.1
0.01
MetalOxide
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0
0.5
1
1.5
2
Zry-2 GNF-Ziron VB
X-ra
y in
tens
ity ra
tio
Fe Sn Cr
0
0.5
1
1.5
2
Zry-2 GNF-Ziron VBX-
ray
inte
nsity
ratio
Fe Sn Cr
LiOHLiOH--water corroded specimenwater corroded specimen Steam corroded specimenSteam corroded specimen
Fe:chemical form change from precipitates in metal to dissolved state in oxide,especially in LiOH oxide due to higher oxidative environment
Cr:almost same distribution in metal and oxideSn:almost same distribution in metal and oxide, except for VB
Relative X-ray Intensity Ratioof In-oxide to In-metal by EPMA Analysis
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0
20
40
60
80
100
0.0 0.2 0.4 0.6 0.8 1.0Relative dissolved iron (-)
Hyd
roge
n pi
ckup
frac
tion(%)
LiOH specimenSteam specimen
Hydrogen pickup fractionHydrogen pickup fractionvs. relative dissolved ironvs. relative dissolved iron
Increase VO・・
Decrease electron
Suppress H・, OHO・ diffusivity
Suppress H・, OHO・mobility
Decrease electrochemical potential
・Oxygen ion defectsFe2O3→ 2FeZr
’ + VO・・ + 3OO
[VO・・] = 1/2[FeZr
’]n=K[FeZr
’]-1/2PO2-1/4
Suppression Effect of Hydrogen Absorptionby Iron Dissolution
Ionic radii of cations (CN= 7)Zr4+: 0.78nmSn4+: 0.75nmFe3+: 0.72nmCr3+: 0.62nmNi2+: 0.69nm
Soluble
Insoluble
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Summary● Hydrogen pickup rate and fraction
- LiOH corroded (linear law) >> Steam corroded (parabolic law)- Decreased with higher iron content in alloys, especially remarkable in LiOH water test
Zry-2>GNF-Ziron>VB
● Oxide layer property- LiOH-water oxide
Degraded grain boundary network seen only in LiOH oxides, except forthin intact layer near metal/oxide boundary Increased hydrogen pickup rates
- Pre-transition steam oxideDouble layer structure of outside mainly m-ZrO2 with faster diffusivity, andinside mainly t-ZrO2 with slower diffusivity (barrier layer of 0.8-0.9 mm )Compressive stress in barrier layer: VB>GNF-Ziron>Zry-2D diffusivity: DH (VB) = 0.5´DH (GNF-Ziron)
- Alloy element behaviorFe: mainly as oxide and metallic precipitates and preferential dissolution into ZrO2Cr: mainly as oxide and metallic precipitatesNi: mainly as metallic precipitates
● Lower hydrogen absorption property in higher Fe and Cr alloys- Higher Fe dissolution into oxide matrix- Higher compressive stress in barrier oxide layer- Ni free effect
Decrease of H diffusivity
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Hydrogen Pickup Property in In-pile andOut-of-pile Conditions of BWR Fuel Cladding
Hydrogen solubility at 300 C
Hydrogen pickup of ZryHydrogen pickup of Zry--2 fuel cladding2 fuel claddingHydrogen pickup fraction inHydrogen pickup fraction in
inin--pile and outpile and out--ofof--pile conditionspile conditions
K. Ogata, et al., 2007 LWR Fuel Performance Mtg.,San Francisco, Sep.30 - Oct.3, 2007, Paper 1024.
M. Aomi, et al., Top Fuel 2009, paris, Sep.6-10, 2009,Paper 2077.
Hyd
roge
n pi
ckup
(ppm
)
Irradiation time (d)
InIn--pilepile
OutOut--ofof--pilepile
InIn--pilepile
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Ellingham Diagram of Alloy Element Oxides
100 200 300 400 500 600-1100
-1000
-900
-800
-700
-600
-500
-400
-300Delta G (Ellingham)
File:‹C
kJ/mol
Temperature
0.67 Cr2O3
2.00 FeO
0.67 Fe2O3
2.00 NbO
NbO2
0.40 Nb2O5
2.00 NiO
SnO2
ZrO2
NiO > Fe2O3 » SnO2 > Cr2O3 > > ZrO2
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Cross Sectional TEM Images ofSteam Oxide at Oxide Surface
40 nm 40 nm
Precipitate
Zry-2 (1.4 mm) VB (1.4 mm)
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Cross Sectional TEM Imagesof LiOH-water Oxide at Middle Location
20 nm
Degraded grain boundaries
(a)
20 nm
Degraded grain boundaries
(b)
ZryZry--2 (1.62 (1.6 mmm)m) VB (1.1VB (1.1 mmm)m)
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Fraction of Oxidation State of Fe, Cr and Niin Oxide Layer Evaluated from XANES Spectra