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Environmentally-Assisted Degradation of Structural ... · PDF file Environmentally-Assisted Degradation of Structural Materials in Water Cooled Nuclear Reactors – An Introduction

Apr 03, 2020

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  • E N V I R O N M E N T A L L Y - A S S I S T E D D E G R A D A T I O N O F S T R U C T U R A L M A T E R I A L S I N W A T E R C O O L E D N U C L E A R R E A C T O R S – A N I N T R O D U C T I O N

    © August 2015

    Advanced Nuclear Technology International

    Analysvägen 5, SE-435 33 Mölnlycke

    Sweden

    [email protected]

    www.antinternational.com

    Environmentally-Assisted Degradation of Structural Materials in Water Cooled

    Nuclear Reactors – An Introduction

    Authors

    F. Peter Ford Rexford, New York, USA

    Peter M. Scott Noisy Le Roi, France

    Pierre Combrade Le Bessat, France

    Claude Amzallag Saint-Etienne, France

  • E N V I R O N M E N T A L L Y - A S S I S T E D D E G R A D A T I O N O F S T R U C T U R A L M A T E R I A L S I N W A T E R C O O L E D N U C L E A R R E A C T O R S – A N I N T R O D U C T I O N

    Copyright © Advanced Nuclear Technology International Europe AB, ANT International, 2015.

    I(V)

    Disclaimer

    The information presented in this report has been compiled and analysed by

    Advanced Nuclear Technology International Europe AB (ANT International®)

    and its subcontractors. ANT International has exercised due diligence in this work,

    but does not warrant the accuracy or completeness of the information.

    ANT International does not assume any responsibility for any consequences

    as a result of the use of the information for any party, except a warranty

    for reasonable technical skill, which is limited to the amount paid for this report.

  • E N V I R O N M E N T A L L Y - A S S I S T E D D E G R A D A T I O N O F S T R U C T U R A L M A T E R I A L S I N W A T E R C O O L E D N U C L E A R R E A C T O R S – A N I N T R O D U C T I O N

    Copyright © Advanced Nuclear Technology International Europe AB, ANT International, 2015.

    II(V)

    Contents

    1 General introduction (Peter Ford) 1-1

    1.1 Definition of the problem 1-2 1.2 Organization of report 1-5

    2 LWR designs and initial material choices (Peter Scott) 2-1

    3 Basic principles of physical metallurgy (Peter Ford) 3-1

    3.1 Carbon and low-alloy steels 3-1 3.1.1 Introduction and applications 3-1 3.1.2 The phases and their effect on mechanical properties 3-4

    3.2 Stainless steels 3-15 3.2.1 Introduction and the “Schaeffler diagram” 3-15 3.2.2 Austenitic stainless steels 3-16 3.2.3 Duplex stainless steels 3-21 3.2.4 Cast stainless steels (CASS) 3-23 3.2.5 High strength stainless steels 3-24 3.2.6 Ferritic stainless steels 3-27

    3.3 Nickel-base alloys 3-28 3.3.1 Introduction 3-28 3.3.2 Ductile, wrought nickel-base alloys 600 and 690 3-28 3.3.3 High-strength nickel-base alloys 3-32

    3.4 Embrittlement issues 3-44 3.4.1 The effect of microstructure on the fracture resistance of stainless steels 3-45 3.4.2 Weldability 3-49

    4 Basics of aqueous corrosion of metals (Pierre Combrade) 4-1

    4.1 Introduction 4-1 4.2 Different forms of corrosion 4-2

    4.2.1 General corrosion 4-3 4.2.2 Selective corrosion 4-3 4.2.3 Galvanic corrosion 4-3 4.2.4 Localised corrosion 4-3 4.2.5 Environmentally assisted cracking (EAC) 4-4 4.2.6 Erosion corrosion 4-5 4.2.7 Cavitation corrosion 4-5 4.2.8 Microbially induced corrosion (MIC) 4-5

    4.3 Main factors affecting corrosion 4-6 4.3.1 Environmental parameters 4-6 4.3.2 Material parameters 4-9 4.3.3 Other influencing parameters 4-12

    4.4 Basics of electrochemistry 4-12 4.4.1 Water and dissolved ions 4-12 4.4.2 Metal/solution interfaces – electrode potential 4-14 4.4.3 Mass and charge transfer through metal/solution interface 4-16 4.4.4 Thermodynamics of corrosion reactions 4-17 4.4.5 Kinetics of corrosion reactions 4-22

    4.5 Aqueous corrosion 4-27 4.5.1 Active corrosion 4-30 4.5.2 Passivity 4-31 4.5.3 Galvanic coupling 4-34

    4.6 Localised corrosion 4-39 4.6.1 Intergranular corrosion 4-40 4.6.2 Localised corrosion by chlorides: pitting and crevice corrosion 4-41

    4.7 Microbially induced corrosion (MIC) 4-50

  • E N V I R O N M E N T A L L Y - A S S I S T E D D E G R A D A T I O N O F S T R U C T U R A L M A T E R I A L S I N W A T E R C O O L E D N U C L E A R R E A C T O R S – A N I N T R O D U C T I O N

    Copyright © Advanced Nuclear Technology International Europe AB, ANT International, 2015.

    III(V)

    4.8 Stress corrosion cracking – general phenomenology 4-54 4.8.1 Introduction 4-54 4.8.2 General phenomenology of SCC 4-55 4.8.3 Overview of processes and mechanisms involved in stress corrosion cracking 4-64 4.8.4 Summary 4-69

    5 Low temperature EAC in LWRs (Pierre Combrade) 5-1

    5.1 Low temperature SCC of stainless steels in LWRs 5-1 5.1.1 Low temperature SCC in primary and auxiliary circuits 5-1 5.1.2 External SCC 5-4

    5.2 SCC of stainless steels in chloride environments 5-5 5.2.1 Effect of environment (potential, pH and temperature) 5-5 5.2.2 Effect of stress 5-10 5.2.3 Atmospheric corrosion of SSs in marine environments 5-11

    5.3 IGSCC of sensitised stainless steels by reactive sulphur species 5-13 5.4 Summary and recommendations 5-14

    6 Water chemistry in light water reactors (Pierre Combrade) 6-1

    6.1 Water radiolysis 6-1 6.2 PWR primary water chemistry 6-3 6.3 PWR secondary water chemistry 6-8 6.4 BWR secondary water chemistry 6-11

    7 Oxidation and cation release of stainless alloys in light water reactors (Pierre Combrade) 7-1

    7.1 Oxidation in high temperature water 7-1 7.2 Surface oxide films 7-1

    7.2.1 Nature of oxides formed in high temperature water 7-1 7.2.2 Oxide layers formed in “low potential” conditions 7-1 7.2.3 Oxide layers formed in “high potential” conditions 7-4

    7.3 Oxidation and cation release rates in PWR primary water 7-5 7.3.1 Oxidation rates 7-5 7.3.2 Cation release of nickel base alloys in PWR primary water 7-6 7.3.3 Parametric effects 7-8 7.3.4 Role of hot functional tests (HFT) 7-10

    8 Flow accelerated corrosion & boric acid corrosion (Peter Scott) 8-1

    8.1 Flow accelerated corrosion (FAC) 8-1 8.1.1 Phenomenology and mechanism of FAC 8-2 8.1.2 Managing FAC 8-5

    8.2 Boric acid corrosion 8-7 8.2.1 Operating experience 8-7 8.2.2 BAC mechanisms 8-10 8.2.3 Corrective actions 8-14

    9 Environmentally assisted cracking in boiling water reactors (Peter Ford) 9-1

    9.1 Introduction 9-1 9.2 Chronology of environmentally-assisted crack growth events 9-2 9.3 Stainless steels 9-4

    9.3.1 Operating experience 9-4 9.3.2 The slip-oxidation mechanism of EAC propagation 9-9 9.3.3 Observed and theoretical parametric dependencies for EAC of unirradiated

    stainless steels in BWRs 9-15 9.3.4 Observed and theoretical parametric dependencies for EAC of irradiated

    stainless steels in BWRs 9-36 9.4 EAC of ductile nickel-base alloys in BWRs 9-45

    9.4.1 Operating experience 9-46

  • E N V I R O N M E N T A L L Y - A S S I S T E D D E G R A D A T I O N O F S T R U C T U R A L M A T E R I A L S I N W A T E R C O O L E D N U C L E A R R E A C T O R S – A N I N T R O D U C T I O N

    Copyright © Advanced Nuclear Technology International Europe AB, ANT International, 2015.

    IV(V)

    9.4.2 Observed and theoretical parametric dependencies for ductile Ni-base alloys in BWRs 9-54

    9.4.3 Summary 9-64 9.5 EAC of high-strength nickel-base alloys in BWRs 9-64

    9.5.1 Operating experience 9-65 9.5.2 Observed and theoretical parametric dependencies for high-strength Ni-base

    alloys in BWRs 9-65 9.6 EAC of carbon and low-alloy steels in BWRs 9-70

    9.6.1 Introduction and operating experience 9-70 9.6.2 Observed and theoretical parametric dependencies for carbon and low-alloy

    steels in BWRs at temperatures >150°C 9-74

    10 EAC in PWRs 10-1

    10.1 Unirradiated austenitic stainless steels (Peter Scott) 10-1 10.1.1 Operating experience 10-1 10.1.2 Laboratory tests 10-4

    10.2 Irradiation effects on stainless steels (Peter Scott) 10-10 10.2.1 Neutron irradiation damage in austenitic stainless steels 10-11 10.2.2 Test reactor and hot laboratory studies of IASCC 10-20 10.2.3 Operating experience 10-27

    10.3 Nickel alloys – primary side (Peter Scott) 10-30 10.3.1 PWSCC of alloy 600 and weld metals 10-32 10.3.2 PWSCC resistance of Alloy 690 and weld metals 10-52

    10.4 Low temperature crack propagation (LTCP) (Peter Scott) 10-60 10.5 Medium and high strength alloys (Peter Scott) 10-64

    10.5.1 Medium strength stainless steels 10-64 10.5.2 High strength nickel-base alloys 10-66 10.5.3 High strength low alloy steels 10-68

    10.6 PWSCC Mechanisms (Pierre Combrade) 10-69 10.6.1 Preamble 10-69 10.6.2 Oxidation of nickel-base alloys in PWR primary water 10-71 10.6.3 Possible mechanisms of PWSCC 10-76

    10.7 Stress corrosion cracking of cold worked stainless alloys (Pierre Combrade) 10-80 10.8 Carbon & low alloy steels (Peter Scott) 10-82 10.9 Steam generator tubing – secondary side (Pierre Combrade) 10-85

    10.9.1 Degradation modes of SG tubes on the secondary side of SGs 10-85 10.9.2 Operating experience of alloy 600 SG tubes 10-92 10.9.3 IGA/IGSCC of SG tubes 10-94 10.9.4 IGA-IGSCC of alloy 600 in the absence of lead 10-98 10.9.5 IGA-IGSCC in the presence of lead 10-102 10.9.6 Comparison of tube materials versus IGA/IGSCC 10-104 10.9.7 Mitigation of secondary side corrosion of SG tubes 10-108

    11 Fatigu

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