Zr-Nb alloys
Materials for the cladding tubes of pressurized-water reactors

This family of Zr-Nb alloys (table ) is widely used for cladding tubes and fuel assembly structural components. It offers an extremely attractive alternative to Zircaloys, particularly for Candu reactors (Z _r N _b 2.5%), but also for VVERs, RBMKs (E110) and PWRs (M5ä).

• At the end of the 1990s, PWR operators' requirements increased, particularly in terms of discharge depletion > 65 GWj/tU and extremely demanding operating conditions for the cladding tube (high Li, Zn injection, increased power, high void ratio). To achieve this, designers and manufacturers have proposed alloys...