Properties of zirconium alloys and their applications in light water reactors (LWRs) - Materials' Ageing and Degradation in Light Water Reactors - page 90

(a) (b)

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4.6 (a) VVER-440 operating FA; (b) VVER-1000 FA (Cox et al. , 2006).

that lead to reactivity losses, most of the FA components within the core
are made of low cross section Zr alloys. These Zr-Sn based alloys are heat
treated to reach optimum mechanical and corrosion resistance properties.
Spring materials need to be made of materials with low stress relaxation
rates, such as Inconel X-750 or Inconel 718. These Ni base alloys are gen-
erally heat treated to reach an optimum precipitation hardening. Table 4.2
presents an overview of alloys used in LWR and their typical compositions.
Table 4.3 provides data for different Zr alloys used by different fuel
vendors (Cox et al ., 2006). It is noteworthy that there are so many differ-
ent Zr-alloys for PWR applications. Originally, Zircaloy-4 (Zr-4) was used
in PWRs, but increased corrosion rates at extended burnups resulted in the