Redesigning the CANFLEX Fuel Bundle to Support CANDU Fuel Development

Abstract

To maintain and improve CANDU's competitive position, the CANFLEX fuel bundle was developed to provide versatility with respect to operational and fuel-cycle options. The 43-element bundle design includes critical heat flux buttons and two element diameters. In an effort to simplify bundle fabrication, it has been redesigned without buttons. In the absence of buttons, geometry modifications including varying the number of planes and height of the bearing pads were made to improve bundle mechanical performance by reducing bundle deformation and maintain bundle thermalhydraulic performance by reducing coolant bypass flow. A three-dimensional finite element model of each design iteration was developed using ANSYS. The models predict the overall geometric deformation of the bundle in response to a given thermal/mechanical load. The analysis indicated that the redesigned bundle with increased number of planes and height of the bearing pads exhibits improved thermal/mechanical behavior than the 43-element bundle.