Numerical investigations of the effect of operation conditions on the heat transfer of the supercritical water in the Canadian SCWR fuel bundle.

The safety of the nuclear reactor depends on the heat transfer of the supercritical water in the fuel bundle. Investigations of effects of operating conditions on the heat transfer of the nuclear reactor are still lacking. In this study, the effects of the operating pressure, inlet temperature, heat flux, and mass flux on the heat transfer of upward supercritical water flow in the 64-element fuel bundle were studied numerically. The criteria of the onset of buoyancy effect on the heat transfer deterioration in circular tubes were also used to evaluate the buoyancy effect on the heat transfer in the fuel bundle. The results show that the wall temperature generally increases with the increase in the inlet temperature, heat flux, or the decrease in the mass flux. The buoyancy-affected zone mainly exists at the pseudocritical temperature region and it will disappear when the mass flux is above a certain value. [Display omitted] • The heat transfer of the supercritical water in the fuel bundle at different operation conditions was investigated. • Criteria of the onset of buoyancy effect on the heat transfer deterioration were evaluated. • The buoyancy-affected zone mainly exists at the region where the bulk temperature is close to the pseudocritical temperature. [ABSTRACT FROM AUTHOR]