Core and plant design of the power reactor cooled and moderated by supercritical light water with single tube water rods

A reactor cooled and moderated by supercritical light water with single tube water rods is designed. The plant system is a once-through direct cycle; the whole coolant which flows once through the core is fed to the turbine. This reactor is much simpler than the current light water reactors L WRs, which enhances its economy. The average outlet coolant temperature should be evaluated considering the mixing of hot and cold coolant from the fuel assemblies. To evaluate this, nuclear and thermal hydraulic analysis of the whole core is carried out considering the effect of coolant density feedback to the radial power distribution. The flow rate in the outer region is reduced by the orifice to maximize the outlet coolant temperature. The average outlet temperature is 397°C, which is only 12°C lower than that of the hottest channel since the density feedback flattens the radial power distribution. Axial and local peaking factors are also evaluated. A steam cycle including reheaters, turbines and feedwater heaters is designed for estimating the thermal efficiency. The reactor with orifices has 40.7% thermal efficiency and 1013 MW electric power. The electric power can be larger in the core without orifices and channel boxes since the channel boxes can be replaced with additional fuel rods. The decrease in the average outlet coolant temperature is only 3°C from the core with the orifices