In this paper, it is attempted to understand the phenomena of iodine stress corrosion cracking of Zircaloy-4 tube, based on that Zircaloy cladding failures in reactor are similar to the results of out-of-pile test iodine vapour.
The main result of this experiment is the relation between the threshold stress which can lead to iodine stress corrosion cracking of Zircaloy-4 tube and the iodine concentration. The critical stress and the critical iodine concentration also obtained.
A model which relates failure time of Zircaloy-4 tube to failure stress and iodine concentration is suggested. The model is described as follows:
$t_F = 5.5 -(3/2)Log_{10}c-4 Log_{10}σ$
where
$t_F$ : failure time, minutes
c : iodine concentration , mg/㎤
σ : stress , 10^4 psi