Postirradiation examination results for the irradiation effects scoping test 1

A zircaloy-clad UO2 fuel rod was operated above its critical heat flux within the in-pile test loop of the Power Burst Facility and later examined in the hot cells. The results of the postirradiation examinations are presented. A Zr-UO2 reaction at the fuel-cladding interface embrittled nearly as much of the cladding wall thickness as the Zr-water reaction on the exterior. Data on both the internal and external reactions and the cladding and fuel microstructures are presented. Cladding embrittlement and rod failure are compared with several rod fragmentation criteria, and conclusions concerning fuel rod failure propagation in a power reactor system are made