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 singl e tube water rods is designed. The plant system is a once-through dire ct cycle; the whole coolant which flows once through the core is fed t o the turbine. This reactor is much simpler than the current light wat er reactors LWRs, which enhances its economy. The average outlet coola nt temperature should be evaluated considering the mixing of hot and c old coolant from the fuel assemblies. To evaluate this, nuclear and th ermal hydraulic analysis of the whole core is carried out considering the effect of coolant density feedback to the radial power distributio n. The flow rate in the outer region is reduced by the orifice to maxi mize the outlet coolant temperature. The average outlet temperature is 397 degrees C, which is only 12 degrees C lower than that of the hott est channel since the density feedback flattens the radial power distr ibution. Axial and local peaking factors are also evaluated. A steam c ycle including reheaters, turbines and feedwater heaters is designed f or 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 degrees C from th e core with the orifices. (C) 1997 Elsevier Science Ltd.