Modelling of Fuel Bundle Deformation Under High-Temperature Transient Conditions

Abstract

CANDU fuel bundle deforms during operation and under postulated AOO and DBA conditions. Bundle deformations under high-temperature (HT) transient conditions are complex and require many new models to be developed, implemented and tested. Candu Energy has developed a computer program prototype to simulate bundle deformations under AOO and DBA conditions. Some examples of new models include those for dealing with transient conditions, HT thermal loads, inter-element contacts at locations other than spacer pads and bearing pads (i.e., sheath-sheath contacts and sheath-pressure tube (PT) contacts), effects of pre-transient conditions (bundle deformations from normal operation prior to AOOs or DBAs), HT sheath creep, and HT material property changes.

This paper describes an overview of Candu Energy’s experience in developing a proprietary computer program, HT version of BOW code (called “BOW-HT” thereafter in this paper) to model fuel bundle deformation under HT transient conditions.