ZIRCALOY-4 CORROSION IN HALIDE SOLUTIONS AND AT CREVICES IN HIGH- TEMPERATURE WATER

Localized corrosion was observed in 0 to 0.004-in, crevice assemblies of Zircaloy-4 to Zircaloy-4 to Inconel exposed 84 days to 750 deg F 1500-psi steam or 680 deg F water adjusted to pH 10.5 with LiOH or NH/sub 4/OH. No accelerated corrosion was observed after 56 days exposure to 680 deg F pH 10.5 to 0.01 M solutions of LiCl, LiI, NH/sub 4/Cl, or NH/sub 4/I with or without Fe/sub 3/O/sub 4/ suspensions in the solutions. Severe attack occurred in Fe/sub 3/O/sub 4/- free 680 deg F 0.01 M LiF and NH/sub 4/F solutions. Although large quantities of Fe/sub 3/O/sub 4/ in suspension decreased attack by decreasing the fluoride concentration of the solution, thin surface deposits of Fe/sub 3/O/sub 4/ on the Zircaloy-4 surface did not appear to increase or retard attack in the 0.01 M fluoride solutions. No unusual corrosion occurred in 680 deg F 0.001 M LiF or 0.0001 M NH/sub 4/F solutions. (auth)