LAUSR

Abstract The effect of dissolved hydrogen (DH) on the general corrosion behavior and oxide films of Alloy 690TT is investigated in simulated primary water at 330 °C. With increasing DH, the structure of oxide film significantly changed and the corrosion rate decreased. At DH = 5 cm 3 /kg H 2 O, the oxide layer was thick, and consisted of outer Ni oxide layer and inner Cr 2 O 3 layer. Under the conditions of DH = 35 and 100 cm 3 /kg H 2 O, the oxide films grew thinner and composed of outer polyhedral spinel oxide particles such as NiCr 2 O 4 or NiCrFeO 4 and an intermediate metallic Ni-rich layer, with inner Cr 2 O 3 layer. The general corrosion rate significantly decreased by about 72% as DH concentration increased from 5 to 35 cm 3 /kg H 2 O. In the range of 35–65 cm 3 /kg H 2 O, the corrosion rate slightly decreased with increasing DH concentration. However, no further changes were observed in the range of 65–100 cm 3 /kg H 2 O.