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

ABSTRACT

This study provides a summary of the conjoint action of hydrogen and irradiation embrittlement in reactor pressure vessel steels and their weldments. The embrittling effect of hydrogen is significant with hydrogen contents of more than 2 ppm in both unirradiated and irradiated pressure vessel steel. The effect of water is pronounced while the impurity content of steel and the hydrogen embrittlement manifest itself as intergranular cracking in particular due to the segregation of phosphorus. This conjoint action is a possible cause for the anomalous fracture behaviour of the pressure vessel steel specimens in the surveillance tests. The stainless steel cladding of the reactor pressure vessel is generally regarded as preventing the hydrogen embrittlement problems affecting pressure vessel steel. If the cladding is broken, the corrosion reactions locally generate elevated hydrogen contents in the pressure vessel steel, which may cause the crack initiation and growth.