The influence some anions and the oxygen dissolved in the medium have uponzircaloy-4 and Zr-2,5% Nb alloys oxidation and hydration

The primary heat transport medium-heavy water in CANDU reactors - is kept a lkaline (at approximately pH 10.5, using LiOH) in order to control the tran sport of corrosion products from the structural materials. in some situatio ns, the primary heat transport medium can be Contaminated by ions of Cl-, F - and dissolved oxygen. To this purpose there,were performed corrosion tests, at high temperature a nd pressure, id aqueous solutions of NaF NaCl and LiOH at pH=10.5, with oxy gen addition in the. range of concentration between 0.1 divided by 10000 pp m, to establish the ions Cl-, F- and dissolved oxygen effect rind their max imum permissible values. The electrochemical measurements through cyclic po larization were performed in the presence of Cl- and F- ions The conclusion referring to the oxidation and hydriding behaviour of zircal oy-4 and Zr-2.5%Nb samples were obtained through gravimetric determinations , electrochemical measurements (cyclic polarization and impedance spectrosc opy) and visual and metallographic examinations of tested samples, in The p resence of each contaminant.