Subcritical crack growth of nuclear components is a current concern in operating light water nuclear reactors. Weld residual stresses (WRS) can drive stress corrosion crack growth, affect fatigue crack growth, lead to reheat cracking issues if the components are operated in the creep regime, and can affect the fracture response of components. This paper provides several examples where crack growth, driven by weld residual stress fields, has led to safety concerns in several nuclear components. This is especially true for the dissimilar metal welds that are present in most PWR reactors. Mechanical mitigation examples are also discussed which are used to reduce the WRS fields or alter them to compression which can mitigate stress corrosion cracking.
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