Assessing the Impact of the 37M Fuel Bundle Design on Fuel Safety Parameters

Abstract

To improve the critical heat flux and margin to fuel dryout in ageing CANDU® nuclear generating stations, the 37-element bundle design (“37R” fuel) has been modified by reducing the central fuel element diameter, producing the new “37M” fuel bundle. The codes FACTAR_SS, ELESTRES, ELOCA, and SOURCE have been used to compare fuel temperature, fission gas release, and sheath integrity in 37R and 37M fuel bundles in Bruce Power nuclear reactors. The assessment demonstrated that, relative to 37R fuel bundles, using 37M fuel bundles does not significantly impact the existing safety margins associated with fuel temperature, fission gas release, and sheath integrity during design basis accidents.