Cladding
Zirconium alloy tube containing fuel pellets, isolating fission products from coolant. 0.6mm thick, corrosion-resistant under neutron flux.
Prevents release of radioactive gases; must withstand 1200°C transients. Common alloys: Zircaloy-4 (Zr-1.5Sn-0.2Fe-0.1Cr). Hydriding limited to <600 ppm. Post-Fukushima, ATF cladding uses FeCrAl or SiC composites.
Why it matters now
Cladding integrity key for NRC licensing of SMRs like Hermes in 2025-2026. ATF cladding enables higher burnup for flexible power markets.
Related reactors
AP1000