Recent progresses in characterization of oxide films and ...€¦ · Radiation Field Examinations Analytical Techniques SEM SE TEM BF 5 Chen et al. (2009) 14th EnvDeg Loop for BWR

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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

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Materials Degradation & CIPS

Coolant

Material integrity

Radiationfield

Corrosion chemistry

K+

Li+

Zn2+Pt

DH

CIPS (AOA)

[B]

ECP

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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

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• 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

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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

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MirrorImage

Step\ Interacted volume is approx Φ40 nm

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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

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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)

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Chen, et al. (2015) 17th EnvDeg

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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

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Fe

Ni Cr

1

(Ni, NiOOH, Ni5O(OH)9,

NiO, Ni(OH)2)

4

(Fe3O4, Fe2O3, FeOOH)

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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

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(I)

(II)

Confirmation of B in Ni2FeBO5

Determination of Phase Compositions of Fuel CRUD

Analytical Techniques: TEM

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Chen, et al. (2012) NPC

Chen, et al. (2014) NPC

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[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

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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.

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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

In cooperation with

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