Book Description
Specimens of Zircaloy-2 have been exposed at 240°C (464°F) in various locations in the primary circuit of the Halden Boiling Water Reactor (HBWR). Corrosion data have also been collected from Zircaloy-2 clad fuel elements. The radiation field caused a drastic enhancement of the attack, corrosion rates increased a hundred times, and was under normal conditions about 0.15 mg/dm2 per day for pickled, anodized, and autoclaved material. Variations in the flux level from 2 x 109 to 3 x 1012 neutrons (n)/cm2 . s (> 1 MeV) had little influence on the corrosion rate, and it is suggested that ?-irradiation or lower energy neutrons, rather than fast neutrons, can be responsible for the corrosion enhancement. When uranium was present in the water, the corrosion rate increased for pickled and for autoclaved fuel rods, while hardly any effect was observed with anodized material. A deliberate fluoride contamination on the specimens increased the corrosion rate in-pile as well as out-of-pile. By anodizing this harmful effect of fluorides could be completely counteracted.