Doel 3 & Tihange 2 - Some Peer-reviewed Scientific Papers & Reports

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Table 6. Different welding methods which were used to manufacture the weld metals presented in Figures 31-34 (Mazel et al., 1983).

Testing environments play a major role in performing hydrogen embrittlement tests. Mazel et al. (1983) discovered that embrittlement is more likely in water than in air (Figure 36 and Table 7). A reason for this could be the reduction of surface energy. It is also known that in aqueous environments, A533B pressure vessel steel cracks easier than it does in air (Figure 37). In pure hydrogen gas, cracking is more likely, as shown in Figure 38. To obtain reliable measurements of the cracking of reactor pressure vessel steel, fracture toughness tests should be performed at different strain rates in simulated reactor water conditions by also simulating the effect of the temperature transients of reactors on the hydrogen content of the pressure vessel steel. To summarise the Russian studies, they have mostly focused on the delayed fracture. The significance of the microstructure for the local hydrogen content has been determined in accordance with the Czech studies. The hydrogen contents reported by Russians (higher than elsewhere) may owe to the technical measurement difficulties. Both the Russian and some of the studies of the ICG-EAC group have indicated how important it is to perform fracture toughness tests in a real environment because water, for instance, plays the major role in increasing the crack growth rate under different reactor conditions.