Corrosion assessment of nickel-based alloys for SCWR fuel cladding application

Supercritical water-cooled reactor (SCWR) is an innovative Generation IV reactor and merits further research and development with the intent of being pursued for implementation in the next 30 years. The SCWR is a high temperature and high pressure water-cooled reactor in which supercritical water (SCW) is used as the primary coolant for a direct once-through cycle to achieve noticeable advantages. For optimum thermal efficiency, the Canadian SCWR concept requires a fuel core outlet temperature of 625 °C at 25 MPa with a predicted peak temperature as high as 800 °C. As a result, material selection for the fuel cladding is one of the most challenging aspects for the realization of the SCWR. Detailed materials assessments based on public data have carried out by Canadian research groups and several nickel-based alloys, such as UNS N06625, UNS R20033 and UNS N07214 alloys, are selected for the fuel cladding. However, significant knowledge gaps exist in determining whether the alloys can be used for the fuel cladding in the SCWR. This paper introduces our most recent laboratory results on corrosion and stress corrosion cracking (SCC) of the nickel-based alloys in SCW.