Study on fretting damage crack behavior of dimple-cladding in nuclear reactor
The fretting behavior between the cladding tube and the rigid convex in the nuclear fuel rod assembly may cause the failure of the assembly,and even threaten the safety of the reactor.This paper takes the dimple-cladding structure in the nuclear fuel rod assembly as the research object to address the crack initiation and propagation under the fretting behavior of rigid-cladding.It employs the finite element simulation method.Our results show the contact area of the cladding tube is consistently under pressure during the circular moving fretting process.The crack is controlled by shear stress in the slip regime,which initiates at the interface between cladding coating and substrate and propagates along the interface,even causing the coating delamination.While in the mix regime and partial slip regime,cracks initiate at the surface or sub-surface of the cladding and propagate to the interior of the cladding,which are controlled by both shear stress and normal stress.Our results show the shear stress is the main cause of the damage of the cladding tube,and plays a primary role in the initiation and propagation of cracks in the fretting behavior of rigid-cladding structures.
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