Heat conduction in nuclear fuel by the Kirchhoff transformation

Realistic simulations of nuclear reactors by computer codes are complex multi-physics problems, coupled through different physical feedbacks on nuclear cross sections. Within these calculations, heat conduction in fuel rods has a crucial importance, especially in thermal reactors, providing the fuel temperature necessary to reproduce the Doppler broadening effect. In this work, the Kirchhoff transformation is applied to solve the non-linear heat conduction problem in the classical fuel rod model. Comparisons with the common numerical scheme based on successive substitutions are presented in a simple case, also discussing the higher computational performances achieved by this integral transformation. Moreover, polynomial approximations are introduced to obtain further computational gain. This technique yields almost analytical fuel temperature distributions, thus ensuring high accuracy in the evaluation of the neutron reactivity from the Doppler effect of nuclear fuel. (C) 2013 Elsevier Ltd. All rights reserved.