Developments in single phase fuel assembly simulations

The heart of every nuclear reactor is the core where the nuclear chain reaction takes place. Heat is produced in the nuclear fuel and transported to a coolant. Most core designs consist of many fuel assemblies which in turn consist of a large number of fuel rods. In most fourth generation reactor concepts (and also in pressurized water reactors), single phase heat transfer plays an important role. For the design and safety analyses of such reactors, simulations of the heat transport within the core are essential. This paper will demonstrate the single phase CFD validation approaches that have been performed by the authors focusing mainly on liquid metal and supercritical water coolants. For turbulence modeling, RANS, URANS, and LES approaches have been applied. It will be demonstrated that CFD analyses indeed support the development of improved heat transfer correlations for application in system codes. (author)