Application of an engineered composite patch toward crack damage mitigation on stainless steel plates

Abstract

High level nuclear spent fuel canisters have been designed and used for nuclear waste storage since the 1950’s. Stress corrosion cracking (SCC) has shown to occur under certain corrosive chemical conditions when the residual stress was not relived in a welded plate. Typical SCC would eventually cause catastrophic failure of structures. In the case of spent nuclear canisters, the radioactive materials may leak through the cracks if they penetrate the tank wall. Early detection of SCC is crucial, followed with appropriate mitigation methods. Various mitigation methods have been funded and explored for the nuclear facilities. Among them, engineered composite patch repairing technique that was originally developed and adopted for aerospace aluminum structures has been proposed as one of the solutions. The technique begins with describing the sample preparation procedures. Based on nondestructive evaluation (NDE) techniques, the bonding between the composite patch and the repaired steel plate was then thoroughly examined using ultrasonic Lamb wave modes. The results were analyzed, and our findings demonstrated that the bonded composite patch was an effective way for crack mitigation. It was observed that they reduced the wave interactions and modified the Lamb wave modes propagation. The results were also helpful in determining the differences between the fully bonded sample and the flawed bonded sample.