Kinetic study of reaction between zirconium and iodine

Abstract

Stress corrosion cracking (SCC) of zircaloy cladding is generally believed to be the major failure mode of current nuclear fuel in light water reactors. Iodine, an abundant fission product, has been identified to possibly cause zircaloy to become susceptible to SCC. An understanding of the kinetics of the reaction between zirconium and iodine is an essential part of the complex iodine induced SCC mechanism. The kinetics of reaction between zirconium and iodine are investigated by TGS-2 thermogravimetry system at the temperature range of 300~350°C. Results show that the activation energy, pre-exponential factor and reaction order of molecular iodine are 43.8 kJ/mole, 3.1 mg/cm 2 -min and 1.06, respectively. A study of the effect of surface texture on the kinetics is also performed by using the different cold rolled specimens whose textures are examined by an X-ray diffraction method. Cold rolling will shift the basal pole to the rolling direction and only influence slightly the pre-exponential factor. The results on zircaloy-4 also indicate that it exhibits better corrosion resistance in the iodine vapor as compared to zirconium. m m w o xmftmm TGS-2 mmm^^mmmmits.m^m±m (&$%m) m fe'ffeRSI^^ Sffiifii^^»JH 43.8 kJ/mole, 3.1 mg/cm 2 /min R 1.06 °j DX#ffifSg^E±«t«S4»^b • ft * [ 0001 ] £«lfiil«tl!3l5fiitft«ffi Downloaded by [Cornell University Library] at 04: