Modeling of three-dimensional steady state non-linear heat transfer in CANDU nuclear fuel Original Research Article

Modeling and analysis of three-dimensional steady-state heat transfer in a CANDU6 nuclear fuel rod are presented in this paper. A special three-dimensional finite element, developed through combining the nine-node two-dimensional isoparametric finite element and the Fourier series, is employed to model the temperature distribution in the pellets and the sheath. To achieve high accuracy and a high convergence rate, the temperature-dependent thermal conductivity matrices of UO2 and Zircaloy are allowed to vary with spatial coordinates in the same manner as temperature within a finite element. The non-linear algebraic equations of nodal temperatures are formulated using the Galerkin method and solved using the iteration approach. A computer code, fuel3d, which contains the finite element modeling and solution schemes described in this paper, was developed for heat transfer analysis of nuclear fuel rods. Numerical simulation results obtained using fuel3d have shown excellent agreement with other independent solutions.