Observations of Dilation and Bowing in Experimental Breeder Reactor II Ducts and Cladding

Irradiation-induced creep and swelling of stain-less-steel Experimental Breeder Reactor II (EBR-II) components have been the subjects of intense surveillance programs during the operation of the EBR-II. Dilation, length change, and bow due to creep and swelling of stainless-steel ducts have all been of concern during the operation of the EBR-II, but in no instance have significant reliability or safety problems arisen due to these phenomena. Driver-fuel elements of two different designs have been irradiated to cladding breach. It was demonstrated that metal driver fuel is capable of high burnup when designed for interconnected porosity prior to fuel-cladding contact. Cladding breaches were found either adjacent to the fuel column or in the fuel-restrainer dimpler. The breach mode was intergranular cracking at both locations.