document: Hydrides, once precipitated in zirconium, degrade the mechanical properties of a component, leading to reductions in tensile strength, ductility and fracture toughness [35–40]. These changes can ultimately compromise the integrity of cladding during normal operating life , accident conditions and fuel storage [13]. As well as the degradation of mechanical properties, the presence of hydrides can also affect phenomena like pellet cladding mechanical interaction (PCMI); or introduce mechanisms for failure, such as delayed hydride cracking (DHC). The former mechanism is the product of thermal expansion in fuel pellets introducing stresses into the cladding, which may then lead to the formation of cracks in areas made brittle by large hydride concentrations [13]. The latter mechanism, DHC, is a sub-critical, time dependent cracking phenomenon that requires long range hydrogen diffusion for repeated local hydride growth and fracture at a hydrostatic tensile stress raiser [5,41,42]. The process occurs over an extended period of time under a continuously applied load that is below the yield stress of the material [5,41,42].
extractive_keyphrases: cladding cracking phenomenon delayed hydride cracking dhc fuel hydride hydrides hydrogen hydrostatic tensile stress raiser pcmi thermal expansion zirconium
abstractive_keyphrases: fuel pellets hydrogen diffusion local hydride growth pellet cladding mechanical interaction