NPP Life Management_vs02

Contents

Contents............................................................................................................................................................... iv

1. Introduction: Doel 3 and Tihange 2 – Hydrogen Flakes and Related Problems ........................................2

1.1. Findings ................................................................................................................................................2

1.2. Causes of the Cracks ............................................................................................................................5

1.3. Amount and Sizes of the Cracks ...........................................................................................................7

2. Hydrogen in Steel .........................................................................................................................................8

2.1. General.................................................................................................................................................8

2.2. Atomic and Molecular Hydrogen .........................................................................................................8

2.3. Water Chemistry, Corrosion Effects and Hydrogen .............................................................................9

3. Hydrogen Source Term: Not Insignificant .................................................................................................12

3.1. General...............................................................................................................................................12

3.2. Corrosion-generated Hydrogen, Equilibrium Pressures and Rates of Formation..............................12

3.3. Other Hydrogen Sources and Hydrogen Traps ..................................................................................16

3.4. Significant Quantities at a Microscopic Level.....................................................................................17

4. Hydrogen Sinks and Accumulation ............................................................................................................20

4.1. General: Hydrogen Concentrations and Trapping .............................................................................20

4.2. Hydrogen Retention in the Flakes......................................................................................................22

4.3. Potential Effects on Material Properties: Mechanical Aspects, HIC, Delayed Cracking or Other Phenomena.....................................................................................................................................................25

5. Final Discussion and Conclusions .............................................................................................................28

6. References ..................................................................................................................................................30