Stress corrosion cracking (SCC)

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Table of contents

Introduction
Chapter 1 State of the art
1.1 Introduction
1.2 PWR secondary circuit
1.2.1 General description
1.2.2 Recirculating steam generator
1.2.3 Thermohydraulics in PWR steam generator
1.2.3.1 Two-phase flow fundamentals
1.2.3.1.1 Two-phase flow system basic notions
1.2.3.1.2 Two-phase flow patterns
1.2.3.2 Thermohydraulics of 51B type steam generators
1.2.4 Materials used in the secondary circuit
1.2.5 PWR secondary flow chemistry
1.2.6 Corrosion phenomena in PWR secondary circuit
1.2.6.1 Stress corrosion cracking (SCC)
1.2.6.2 General corrosion and Flow accelerated corrosion (FAC)
1.2.6.3 Parameters affecting flow accelerated corrosion – TSP clogging source
1.2.6.3.1 Effects of pH and temperature – magnetite solubility
1.2.6.3.2 Effect of oxygen concentration
1.2.6.3.3 Effect of material composition
1.2.6.3.4 Effect of thermohydraulics
1.3 Properties of magnetite particle
1.3.1 Structural property
1.3.2 Magnetite surface charge
1.3.2.1 Electrical double layer (EDL)
1.3.2.2 Zeta potential
1.3.2.3 Surface characterizations of magnetite
1.4 Steam generator degradation phenomena
1.4.1 Tube fouling
1.4.2 Tube Support Plate clogging
1.4.2.1 TSP clogging consequences
1.4.2.2 TSP clogging diagnosis
1.4.2.2.1 Televisual inspections
1.4.2.2.2 Wide Range Level (WRL) monitoring in stationary regime
1.4.2.2.3 Eddy current inspection
1.4.2.3 NPP feedbacks of TSP clogging
1.4.2.4 Current countermeasures
1.5 Phenomenology of TSP clogging formation
1.5.1 Magnetite particle deposition
1.5.1.1 Previous experimental studies
1.5.1.2 Magnetite particle deposition models
1.5.1.2.1 Transport step
1.5.1.2.2 Attachment step
1.5.2 Surface precipitation
1.5.2.1 Attainment of solubility
1.5.2.2 Formation of nuclei
1.5.2.3 Growth of crystals
1.5.3 Specific TSP clogging formation mechanisms at the inlet of TSP
1.5.3.1 Vena contracta mechanism
1.5.3.2 Flashing
1.5.3.3 Results of modelling study comprising vena contracta and flashing
1.5.3.4 Electrokinetics
1.6 Conclusions of Chapter 1
Chapter 2 Experimental investigation of TSP clogging phenomenon
2.1 Introduction
2.2 Representative experiments
2.2.1 Global deposit build-up tool under representative conditions: COLENTEC facility
2.2.2 COLENTEC – 2015 experimental conditions
2.2.3 Materials used for COLENTEC test
2.2.4 Characterization results of COLENTEC-2015 samples
2.2.4.1 Optical and SEM observations
2.2.4.2 TEM investigations
2.2.4.2.1 Characterization of titanium thin section
2.2.4.2.2 Characterization of stainless steel thin section
2.3 Simulated experiments
2.3.1 Description of autoclave tests
2.3.2 Iron incorporation into stainless steel corrosion layer
2.3.3 Ti/SS galvanic corrosion effects
2.4 Conclusions of Chapter 2
Chapter 3 Specific experimental investigation of deposit build-up by electrokinetic phenomenon
3.1 Introduction and basic notions of electrokinetically induced deposit
3.2 Literature review relative to the effects of water chemistry and thermohydraulics on electrokinetic deposit build-up
3.3 Experimental system
3.4 Experimental conditions
3.5 Results
3.5.1 Morphology and characterization of the deposits
3.5.2 Deposit build-up rates
3.6 Discussions
3.6.1 Effect of flow velocity
3.6.2 Comparisons with COLENTEC results and EDF observations
3.7 Conclusions of Chapter 3
Chapter 4 Numerical investigation of TSP clogging phenomenon
4.1 Introduction
4.2 Hypotheses and input data
4.2.1 Hypotheses
4.2.2 Input data
4.3 Results
4.3.1 Phenomenon prioritization with different particle sizes
4.3.2 Phenomenon prioritization with different total iron concentrations
4.4 Discussions
4.5 Conclusions of Chapter 4
Chapter 5 Overall conclusions and perspectives
References
Appendix A Scanning Electronic Microscope
Appendix B Transmission Electronic Microscope
Appendix C Synthesis of CeO2-Fe3O4 core-shell particles