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

J. Koutsk~, K. Splichal

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(a) (b) Intergranular fracture of notched specimens, delayed fracture test: (a) crack initiation near the surface; (b) local region on the surface.

Fig. 10.

fracture; in these cases the influence of inclusions is suppressed. Failure is initiated by intercrystalline fracture on the surface which focuses either in the local area or in the coherent layer under the whole surface of the specimen (Fig. 10).

Hydrogen trapping and release

The CrMoV steel in the as-delivered state contained 0.4-0.6ppm and after irradiation 1.2-2.0ppm of hydrogen. The dependence of the hydrogen content on charging current density was characterized by two stages. In the first, the hydrogen content in irradiated and unirradiated specimens reached 2-3 ppm. In the second, the course of the hydrogen charging curve is determined by the presence and activity of trapping sides, which after irradiation are dependent on the level of radiation damage in the steel. With decreasing irradiation temperature (i.e. increasing radiation damage of the steel) the hydrogen content increases after irradiation at 290°C by approximately up to 1.5 times and at 130°C by 3-4 times, as shown by Koutsk~, e t a l . ~ The effect of traps for hydrogen embrittlement was evaluated from the course of hydrogen charging and hydrogen release in both the unirradiated specimens and those irradiated at 290°C to a fluence of 3"4 x 1023nm-2(Figs 11 and 12).