Numerical Studies of Flow and Heat Transfer Around Fuel-Element Bearing Pads

Abstract

Fuel-bundle appendages such as bearing pads, inter-element spacers and end-plates, affect the thermalhydraulic performance of a typical CANDU fuel channel by increasing its pressure drop and enhancing fuel-to-coolant heat transfer. To quantitatively account for these effects in subchannel or system codes. adequate characterization of individual appendage contributions to these effects is required. In view of the difficulties and costs of experimental characterization we are using the tools of Computational Fluid Dynamics(CFD) to estimate the important parameters from simulations alone. In this paper we report the results of numerical studies of flow and heat transfer around the Bruce-type bearing pad in an annulus-flow configuration. Both the pressure-drop and heat-transfer characteristics were generated for the actual bearing pad geometry, using the TASCflow software package. This paper discusses issues in applying the modern CFD tool effectively, and indicates the implications of the findings for the modelling of CANDU bearing pads in the ASSERT subchannel code.