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

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Table 5. The effect of neutron irradiation on the tensile test results of 15Kh3MFA steel (T = 20°C) (Alekseenko et al. 1977).

Mazel et al. (1978) studied the increase of the hydrogen content of 12X2M ĭ A steel in simulated PWR water. The hydrogen content of the welds of the initial state was 0.3-0.7 cm 3 H/100 g Fe. In the reactor water at 325°C, the hydrogen content increased to the average value of 1.29-1.33 cm 3 H/100 g Fe, but local maximum contents reached as high as 5.25 cm 3 H/100 g Fe. With the cathodic hydrogen charging, the hydrogen content that was obtained was 7.5 cm 3 H/100 g Fe. Figure 31 shows the effect of the high hydrogen content on the impact test results with the base material and weld material of 15Cr2NiMoVA steel. Figures 32-34 display the results of the fracture mechanical tests of different weld metals (Table 6) (bending test specimen 15 x 15 x 150 mm, which has a sharp notch, r n = 40 µm) as a function of hydrogen content, strain rate and temperature. When the temperature rises, the potential for hydrogen embrittlement decreases and at a reactor operation temperature of 325°C, it is very low. The weld metal of the pressure vessel steel of VVER-440 reactor is more susceptible to hydrogen embrittlement than that of VVER-1000 steel (Figure 35). This is due to the greater amount of impurities in steel (Sb, Sn, Zn and Pb), which increase the hydrogen embrittlement tendency and the role of the intergranular cracking.