Chemical reactions of Zircaloy-4 and zirconium with (i) dicaesium telluride, Cs 2Te, (ii) caesium tellurite, Cs 2TeO 3, and (iii) tellurium, under different oxygen potentials

• Published in: Journal of nuclear materials Vol. 223; no. 3; pp. 277 - 285
• Main Authors: Pulham, R.J., Richards, M.W., Kennard, D.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1995
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/0022-3115(95)00010-0

Although Zircaloy-4 and Zr foil are inert to solid Cs 2Te at 948 K, reaction occurred when O 2 was admitted from buffers in sealed systems over 168 h. The products consisted of a zirconium telluride (or caesium zirconium telluride) sandwiched between the foil and an outer layer of ZrO 2, thus hindering the release of Te. The depth of corrosion of the foil increased with an increase in oxygen potential. Similar experiments with caesium tellurite, Cs 2TeO 3(s), with and without buffers, caused more extensive corrosion although Zircaloy-4 was more resistant than Zr; the tellurite was reduced to Cs 2Te and Zr was oxidised to ZrO 2. Zircaloy-4 and Zr reacted with liquid Te to form a surface layer of ZrTe plus unidentified phases that seemed to be neither Zr 3Te nor Zr 5Te 4, but Zircaloy-4 was more resistant again than Zr. When oxygen was introduced from buffers, the ZrTe was then converted to ZrO 2. There was some evidence that tellurium in the form of ZrTe was sandwiched again between ZrO 2 and the substrate foil. Increasing the oxygen potential from −914 to −307 kJ mol −1 O 2 increased the depth of corrosion and the extent of ZrO 2 formation.