A new procedure for solving steady-state and transient-state nonlinear radial conduction problems of nuclear fuel rods

Half-boundary method (HBM) is extended to solve one-dimensional radial conduction problems in nuclear fuel rods. The accuracy and efficiency of HBM are first tested by solving three one-dimensional radial conduction problems in cylindrical coordinates. They are steady-state and transient-state problems with linear and nonlinear material properties. HBM shows a comparable accuracy to the analytical solutions, and a higher accuracy than finite volume method (FVM) especially with fewer elements in the discretized model. Besides, the computation time ratio of HBM to FVM decreases as the element numbers increase, and it is only 0.16% when 1000 elements are involved. In order to further validate the practical applicability of HBM, nonlinear heat conduction problems of nuclear fuel rods (NFRs) are solved by HBM. The numerical results of NFRs are carried out both in steady-state and transient-state cases. HBM has a matched result with ANSYS. In addition, the size effect of pellet, helium gap and zircaloy cladding on the highest temperature in NFRs is also studied using HBM. The pellet dimension affects the highest temperature mostly.