AXIAL FUEL ROD EXPANSION MODEL IN NODAL CODE DYN3D FOR SFR APPLICATION

摘要

The nodal diffusion code DYN3D is under extension for Sodium cooled Fast Reactor (SFR) applications. As a part of the extension a new model was developed for axial thermal expansion of fuel rods. The model provides a flexible way of handling the axial fuel rod expansion, i.e., each sub-assembly and node can be treated independently. In the current paper the new model is described in details. The performance of the model is assessed on a large oxide SFR core from the OECD/NEA benchmark. The test calculations cover the open and the closed gas gap cases. The results are compared to the reference full core Serpent Monte Carlo solutions. The test results reported in the paper indicate that the proposed model can accurately account for the axial expansion effects on the full core level.