Modelling Transient Two-Dimensional Nonlinear Temperatures in Nuclear Fuel Using the Feat Code

Abstract

A capability to model transient two-dimensional heat conduction has been added to the FEAT code, and is described in this paper. Results from the test cases show excellent agreement between FEAT calculations and corresponding analytical solutions. An illustrative example discusses the transient temperature in the pellet during a hypothetical loss-of-coolant accident in a CANDU® 9 reactor. Two-dimensional calculations are performed to account for the effects of end-flux peaking and heat transfer through the endcaps. The case studies have shown that the net effect is to increase the peak pellet temperature by about 176 °C compared to the one- dimensional situation of no end-flux peaking and no axial heat transfer through the endcap. Nevertheless, the peak pellet temperature of 2154 °C is well below 2840 °C, the melting point of UO₂.