Fuel Testing to Simulate Darlington Channel and Fuel Damage

Abstract

The fatigue limits of the endplate-to-endcap welds of the Ontario Hydro 37 element fuel bundle were established by testing small specimens. The results indicated an effective stress concentration factor of four due to the weld geometry. Higher mean stress reduced the fatigue limit in samples which failed in one million cycles. For tests carried out at high R-ratio, a stress amplitude of 45 MPa produced failures between 10' and lo6 cycles. The fractographic features of the Darlington fuel bundle endplate cracks are consistent with the features of the low stress high cycle fatigue cracks produced in the small specimen test program.