A FEASIBILITY STUDY ON CORE COOLING OF REDUCED-MODERATION PWR

摘要

In this study, we have performed a feasibility evaluation on thermal-hydraulic design of RM-PWR type core. The present design adopts seed assemblies and several blanket assemblies. In the blanket regions, power density is lower than that of the seed regions. Then, we set a channel box to each fuel assembly in order to adjust the flow rate in each assembly, because the possibility that the coolant boils in the seed assemblies is very high. In the feasibility evaluations for a normal operation, subchannel code COBRA-IV-I was used in combination with KfK DNB correlation for a tight lattice bundle. Based on one assembly calculation, coolant boiling was found not to be occurred, when coolant mass flow rate to the blanket assembly is reduced by around 45% of averaged value, and that to the seed fuel assembly is increased. Provided that the channel boxes only to the blanket assemblies are set up and the coolant mass flow rate to the blanket fuel assembly is reduced by 45%, it was confirmed by the whole core calculation that the boiling of the coolant is not occurred.