Simulations of CANDU Fuel Bundles Under Static Mechanical Loads and Refuelling Loads Using LS-DYNA Finite Element Models

Abstract

LS DYNA is a commercial general purpose finite element code for analyzing static and dynamic response of structures. It is used by Candu Energy in the analysis of CANDU® fuel bundles subjected to static mechanical loads, and refuelling loads when the fuel bundle string is supported by Fuelling Machine side-stop separators to resist the hydraulic loads from coolant flow in the fuel channel. The analysis calculates deflections and local stresses / strains in the bundle. When modelling these conditions, the LS DYNA fuel models consider the non-linear mechanisms for the following phenomena: mechanical driving forces (gravity, hydraulic drag and friction force etc.), contact constraints on bundles at side-stops, inter element contacts through the mating spacers, fuel elements to pressure tube contact at bearing pads, endplate to endplate contacts in fuel string, and bundle misalignment in fuel string etc. This paper describes the LS-DYNA models and simulations of CANDU fuel bundles under static mechanical loads and refuelling loads.