Investigation of conjugate heat transfer phenomena in advanced fast reactors

In this work conjugate heat transfer associated with flow of sodium in the annulus under decay heat removal mode of advanced fast reactors has been studied. The coupled governing equations of momentum and energy are solved numerically and analytically. TEACH code with SIMPLE algorithm has been used for the internal forced flow and wall regions. For turbulent flow, k-ε model is employed. Integral method is used for natural convection. Results are presented for the two-dimensional temperature field in the fluids and the solid for both laminar and turbulent flows. It is shown that a substantial amount of energy exchange between the hot or cold pool and the sodium flowing in the annulus occurs via the liner. As a result convective boundary layers form along the liner. The convective motion leads to a stratified flow along the redan. The fluid stratified in the hot pool can under certain conditions drain down the radial blanket or be entrained by fluid exiting the core. The heat transfer across the liner also increases the average temperature of the sodium flowing in the annulus and thereby reduces the hydrostatic head available for driving the fluid through the core.