Microstructure and hydrides in the near rolled-joint regions of ex-service CANDU pressure tube

Li, W.; Hanlon, Sean; Bickel, G. A.; Buyers, A.G.; Walters, Lori; Long, Fei

doi:10.1016/j.jnucmat.2020.152316

Cited by 6 publications

(1 citation statement)

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“…During cooling, the remaining <a> and <c> dislocations can act as heterogeneous nucleation sites for hydride, probably causing the precipitation–memory effect ( Figure 4 d) [ 42 , 59 ]. The precipitation–memory effect is also present in Zr-2.5Nb alloys [ 60 , 61 , 62 ]. After annealing at 350 °C, hydrides cross multiple phase interfaces and grain boundaries (GBs) and nucleate at unvarying sites.…”

Section: Hydride Nucleation and Growth Behaviorsmentioning

confidence: 99%

Mechanisms of Hydride Nucleation, Growth, Reorientation, and Embrittlement in Zirconium: A Review

Jia

Han

2023

Materials

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Zirconium (Zr) hydrides threaten the reliability of fuel assembly and have repeatedly induced failures in cladding tubes and pressure vessels. Thus, they attract a broad range of research interests. For example, delayed hydride cracking induced a severe fracture and failure in a Zircaloy-2 pressure tube in 1983, causing the emergency shutdown of the Pickering nuclear reactor. Hydride has high hardness and very low toughness, and it tends to aggregate toward cooler or tensile regions, which initiates localized hydride precipitation and results in delayed hydride cracking. Notably, hydride reorientation under tensile stress substantially decreases the fracture toughness and increases the ductile-to-brittle transition temperature of Zr alloys, which reduces the safety of the long-term storage of spent nuclear fuel. Therefore, improving our knowledge of Zr hydrides is useful for effectively controlling hydride embrittlement in fuel assembly. The aim of this review is to reorganize the mechanisms of hydride nucleation and growth behaviors, hydride reorientation under external stress, and hydride-induced embrittlement. We revisit important examples of progress of research in this field and emphasize the key future aspects of research on Zr hydrides.

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