Fuel Cladding Embrittlement:

Corrosion of zircaloy in water results in the release of hydrogen. A portion of the hydrogen released, ranging from about 5 percent to 20 percent, diffuses by the oxide layer and into the metal. That causes embrittlement of the base metal which could lead to cladding failure. The zirconium alloy zircaloy-2 that has been used widely as a fuel-rod cladding is subject to hydrogen embrittlement, especially in the vicinity of surface defects. The alloy zircaloy-4 is, however, less susceptible to embrittlement. As with metals in common, irradiation decreases the ductility and raise the embrittlement of the zircaloys and zirconium. A magnitude of the radiation effect depends upon the neutron spectrum, fluence, temperature, and microstructure (or texture) of the material. Variant fabrication processes yield products along with different textures; thus, the radiation embrittlement of zircaloy is dependent on its fabrication history.

Irradiation at high temperatures could lead to brittle fracture of stainless steels used as cladding in quick liquid metal breeder reactors.