Corrosion problems in a heavy-water vessel. Experience with 2 years active operation of the A1 reactor

The heavy water reactor vessel of Al-Mg-Si aluminium alloy, in contact with deuterium oxide saturated with carbon dioxide at a temperature of 900C, also containing products of radiolysis and corrosion, was examined for corrosion after two years operation. The parts considered most exposed to corrosive conditions were sampled and so were control rods removed during repairs. For most of the time a corrosive inhibitor was added (10 months) and this reduced the degree of corrosion, which was comparitively rapid when the vessel first went into service and then declined to a practically constant state. Corrosion was greater during operation than when power was not being generated. (author)