Proof of Concept Validation Results of the FAST Fuel Element Model

Abstract

The Fuel And Sheath modelling Tool (FAST) is a fuel performance code that is being developed for both normal and transient operating conditions. The FAST code includes models for heat generation and transport, thermal-expansion, elastic strain, densification, fission product swelling, pellet relocation, contact, grain growth, fission gas release, gas and coolant pressure and sheath creep. These models are coupled and solved on a two-dimensional (radial-axial) geometry of a fuel pellet and sheath. This paper outlines the results of an ongoing proof of concept validation of the code conducted as part of the development process. The validation compared model predictions against both experimental data and results obtained from the ELESTRES and ELOCA fuel performance codes. Overall, the results show excellent model performance except in cases of strong axial dependence.