Post-Irradiation Examination of Two Gentilly-2 Bundles to Investigate the Effect of Pressure Tube Diametral Creep on Fuel Performance

Abstract

Two bundles, discharged in 1997 from the Gentilly-2 Nuclear Generating Station, were selected for post-irradiation examination to investigate the effect of pressure-tube diametral creep on fuel performance. The bundles were irradiated in a pressure tube that had experienced relatively high diametral creep (maximum = 2.5%); these operated at peak outer-element linear powers of 48 and 52 kW/m to bundle-average burnups of 179 and 163 MWh/kgU, respectively.

Bundle orientation in the channel was determined fiom bearing-pad wear marks on individual elements. Residual sheath strain, fission-gas release and UO₂ grain growth were measured on elements located at the top and bottom of each bundle. All observed performance parameters were within the expected range, and there was no apparent difference between elements irradiated at the top and bottom of the bundle/channel. It is concluded that pressure-tube diametral creep had no measurable impact on the performance of these bundles.