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Recent progresses in characterization of oxide films and deposits on reactor materials at Studsvik
Jiaxin Chen, Sr. Specialist (Studsvik) and Adjunct Prof. (Chalmers Univ. Tech.)
International Light Water Reactors Material Reliability Conference and Exhibition, August 1-4, Chicago, USA
Studsvik facilities for fuel and materials examinations
Materials Technology Department
2
Materials Degradation & CIPS
Coolant
Material integrity
Radiationfield
Corrosion chemistry
K+
Li+
Zn2+Pt
DH
CIPS (AOA)
[B]
ECP
3
1. Introduction
2. Analytical techniques - examples
2.1 Trace cobalt conc profile w/ WDS using TEM-lamella
2.2 Thin film porosity w/ EELS/TEM
2.3 Derivation of metal thinning rate w/ combined techniques
2.4 Phase identification of suspended particulates in reactor coolant
2.5 Instant draining at high temperature and high pressure
3. Summary
Outline
4
• Studsvik simulation loops (BWR/PWR)
• Effects of [Fe]/[Ni]/[Zn], T, flow, ECP (BWR) and pH, T, shutdown chemistry (PWR)
• FIB/FEG-SEM
• Topography of oxide films and deposits, TEM-lamella liftout
• WDS analysis of trace cobalt and concentration profiles in oxide film using TEM-lamellas
• FEG-TEM
• Microstructural characterization of oxide films
• Determination of the inner oxide layer porosity with EELS
• APT, XRD, Raman, etc.
Radiation Field Examinations
Analytical Techniques
TEM BFSEM SE
5
Chen et al. (2009) 14th EnvDeg
Loop for BWR coolant simulation
Metal substrate
Inner oxide layer
Outer oxide layer
Metal substrate
Inner oxide layer
Outer oxide layer
0 5 10 15 20 25
0.00
0.02
0.04
0.06
0.08
0.10
0.12
Appare
nt concentr
ation [C
o], w
t%
Spectrum
MetalOxide layer
~1.25 mm
Pt
Probe current 137 nA
2.1 Determination of [Co] in Oxide Films (SS316L)
Exposures:BWR (NWC)280C1147 h (total)647 h w/ 0.1 ppb [Co]
Analytical Techniques: WDS+TEM-lamella
6
MirrorImage
Step\ Interacted volume is approx Φ40 nm
7
http://dx.doi.org/10.1590/S1516-14392003000200010
Maria Auxiliadora das Neves NogueiraI
This study
Outer oxide layer Inneroxide layer
Questions
wat
er
Analytical Techniques: EELS/TEM
2.2 Determination of Thin Film Porosity
HAADF
8
~70
nm
9
Dimension: 0.59x0.59 micronPixel size: 0.011x0.011 micron
Metal
Oxide
Corroded Alloy 182
[Chen, et al. NPC2016 Paper 116]
Analytical Techniques: EELS/TEM
• Oxide film growth vs. Metal thinning– Derivation of a simple equation
• Application of combined analyticaltechniques
• Oxide film thickness measurement by infrared ellipsometry
• Porosity measurement by EELS/SEM image analysis
• Phase analysis by electrondiffraction/TEM and XRD
2.3 Corrosion Kinetics Examination
Analytical Techniques for Metal Thinning Rate
TEM BF
10
Gustafsson, et al. (2013) 16th EnvDegChen, et al. NPC2014
oxide weight
0 3 6 90
2
4
6
Con
sum
ed
meta
l (m
m)
Time (week)
A82FeLow
A82FeHigh
A182
A52M
A152
A600
0 3 6 90
2
4
6
8
10
Ox
ide f
ilm
th
ick
ness
(m
m)
Time (week)
A82FeLow
A82FeHigh
A182
A52M
A152
A600BWR, NWC
Metal Thinning and Oxide Film Growth
Corrosion of Nickel-base Alloys in BWR (NWC)
11
Chen, et al. (2015) 17th EnvDeg
12
X = 1.25022√t.
Corrosion Kinetics
Alloy 182 in BWR (NWC)High flow velocity
[Chen, et al. NPC2016 Paper 116]
Parabolic law
How do we identify ”nickel” among various phases?
Ni
Ni (m)
NiO
NiOOH
Ni(OH)2
Ni5O(OH)9
Ni2FeBO5
NiCr2O4
(Ni,Fe,Cr)3O4
(Ni,Fe,Cr)2O3
…
Fe-Cr-Ni-H2O [Meaq]tot=10-8 MReproduced from B. Beverskog
Pourbaix diagram
”Plant data”
B. BEVERSKOG, “Oxide Stability in PWR-environments,” Studsvik Material Report, Studsvik/M-96/75, 1996-06-28.
”Nickel” in PWR Fuel CRUD and Primary Coolant
13
Fe
Ni Cr
1
(Ni, NiOOH, Ni5O(OH)9,
NiO, Ni(OH)2)
4
(Fe3O4, Fe2O3, FeOOH)
7
Cr8O21
3
NiFe2O4
26 FeCr2O4
(Ni,Cr,Fe)3O4
(Ni,Cr,Fe)2O3
Ni2FeO3
5
TEM-grid
2.4 Phase Identification of Suspended Particulates in Coolant
Capture particulates for TEM/EDS/EELS analyses
Ni2FeBO5
14
(I)
(II)
Confirmation of B in Ni2FeBO5
Determination of Phase Compositions of Fuel CRUD
Analytical Techniques: TEM
15
Chen, et al. (2012) NPC
Chen, et al. (2014) NPC
16
[S]/[Ag]
0.6
[S]/[Ag]
0.6
Ag2S in LWR coolant[Chen, et al. NPC2016 Paper 89]
Ringhals unit 4 (PWR)
Forsmark unit 2 (BWR)
Dose Rate Issue with Ag-110m
2.5 Studsvik Instant Draining Technology
New ”blowdown” pathPower off at draining
Sampling at High Temperature and High Pressure
Capturing K-, Li- and B-species in crud/oxide layers
17
Li2B4O7 grains caught in simulated fuel crud
2332.092.11
4002.372.42
2312.552.56
1322.592.592656
1161.661.64
2511.731.7
3322.052.062651
2511.741.74
2421.961.96
1124.074.152650
2332.092.12
4002.372.43
1124.084.085649
hkldrefdexpImage nr
2332.092.11
4002.372.42
2312.552.56
1322.592.592656
1161.661.64
2511.731.7
3322.052.062651
2511.741.74
2421.961.96
1124.074.152650
2332.092.12
4002.372.43
1124.084.085649
hkldrefdexpImage nrTEM BF
18Doncel, Chen et al. (2006) NPC
Summary
• Examples of applying modern analytical techniques to solve somepractical problems in LWR have been demonstrated.
• Modern micro-analytical techniques are opening up many uniqueopportunities to do much more than we had imagined.
• Combined with new sampling preparation methodologies and well-designed laboratory simulation, the new analyticaltechniques can greatly improve our current understanding aboutmaterial behavior in LWR.
19
The electron microscopy work mentioned in this presentation has been conducted in cooperationwith Mr. H. Bergqvist (formally Royal Institute of Technology), Prof. L. Belova (Royal Institute ofTechnology), Dr. F. Lindberg (KIMAB) and Mr. D. Jädernäs (Studsvik).
Technical contributions from Mr. J. Lejon (OKG), Mr. B. Bengtsson (RAB), Mr. J. Hägg (RAB), Mr. B. Forssgren (RAB), Ms. M. Tanse-Larsson (FKA), Dr. M. Olsson (FKA), Mr. C. Massimo (FKA), Ms. H. Johansson (FKA), and other colleagues from Swedish nuclear power plants are gratefullyacknowledged.
Ms. C. Obitz and Dr. P. Anderssoon (Studsvik) participated in the mentioned corrosion studies and TEM-sample preparation. Mr. P. Gillén, Mr. J. Syrjänen and other Studsvik colleagues wereinvolved in the mentioned AOA work and some test rig design and construction work.
Financial support by the Swedish Nuclear Power Utilities, Swedish Radiation Safety Authority, ENUSA and EPRI is gratefully acknowledged.
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Acknowledgements