Corrosion and hydriding of zirconium alloys in nuclear environments

Zircaloys are being used as fuel cladding materials in different types of reactors. Due to the present demand for extended burn up, better performance of the claddings is the need of the day. Though zircaloys are the most suitable materials for the claddings, they undergo different types of corrosion, including hydriding. Pressure tubes which are made of Zr-Nb alloy also suffer from hydriding. Further extensive investigations are required to understand the various corrosion mechanisms and also to extend the life of these in-core components by the suitable control of materials composition and structure, environment and operation. The present day problems related to the zircaloys have been discussed in this paper in the light of the experiences gained in this laboratory as well as elsewhere with some suggestions in which future investigations need to be directed. (author)