Modelling of Heat Transfer Between Two Fuel Subchannels in Supercritical Water Conditions Using Computational Fluid Dynamics

Abstract

This paper investigates the application of FLUENT in simulating a SuperCritical Water Reactor (SCWR) pressure tube type design. Computational Fluid Dynamics (CFD) can be used to study the unstable behaviour around pseudo-critical conditions along the fuel channel. In SCWRs, the coolant reaches its pseudo-critical temperature early in the reactor core and thermophysical properties undergo dramatic changes.⇥The heat-transfer mechanism along the fuel channel also changes beyond the pseudo-critical point due to the fluid acting more like a gas-like.
The subchannels between different rings in the fuel string receive different heat fluxes and as a result, different heat transfer rates. The pseudo-critical point for different subchannels may occur at different axial locations. While experiments will be required to properly understand this effect, it is important to determine the current prediction capability of CFD type codes for this phenomenon as it will assist in defining the type of validation exercises necessary for design activities.