(A) study on iodine stress corrosion cracking of zircaloy-4 tube

Abstract

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