Effects of process-generated hydrogen on RPV walls

List of Figures

1.1 Schematic representation of a PWR. . . . . . . . . . . . . . . . . . . . . 5 1.2 Schematic representation of a RPV. . . . . . . . . . . . . . . . . . . . . 7 1.3 Schematic representation of a RPV. . . . . . . . . . . . . . . . . . . . . 9 2.1 Examinated zones in 10-yearly quality control of the RPV. . . . . . . . 12 2.2 Schematic representation of an underclad defect. . . . . . . . . . . . . . 12 2.3 Stresses in a RPV wall. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.4 Machine used for UT inspection. . . . . . . . . . . . . . . . . . . . . . . 14 2.5 Distribution of the indications as function of depth in Doel 3 (2012). . . 14 2.6 Distribution of the indications as function of depth and height in Doel 3 (2012). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.7 Schematic representation of macro-segregation in a large ingot. . . . . . 16 2.8 Solubility of hydrogen in iron as a function of temperature. . . . . . . . 17 2.9 Micrograph of hydrogen flake with MnS precipitates. . . . . . . . . . . . 17 2.10 Micrograph of a hydrogen flake fracture surface. . . . . . . . . . . . . . 18 2.11 Material susceptibility to hydrogen flaking as function of hydrogen and sulphur concentration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3.1 Reaction mechanism of molecular hydrogen absorption in metallic material. 22 3.2 Octahedral and tetrahedral interstitial lattice sites in a bcc lattice. . . . 23 3.3 Temperature and pressure dependent solubility of hydrogen in iron. . . 24 3.4 Types of microstructural lattice defects acting as hydrogen traps present in a steel component. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3.5 Experimental values for the solubility constant and the diffusion coefficient of hydrogen in steel as a function of temperature. . . . . . . . 28 4.1 Typical primary water chemistry conditions in a PWR during operation. 31 4.2 Reactions due to ionizing radition in water. . . . . . . . . . . . . . . . . 34 5.1 Henry constant for hydrogen gas in light water at high temperatures in GPa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 5.2 Density of water as a function of temperature at a pressure of 150 bar. . 41 5.3 Henry constant for hydrogen gas in light water at high temperatures in mol/m 3 Pa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 iv