Safety analysis of a Super LWR with double tube water rods

A Super LWR with double tube water rods core had been designed for simplifying the upper core structure. Coolant flows upward in the fuel channels. Water inventory in the upper dome of the reactor pressure vessel was available for core cooling for the previous two-path core design, but not for the present one. Safety analysis was conducted to evaluate the safety performance of the present core design. Events of abnormal transients, accidents, and ATWS were included in the analysis. It is clarified that the water inventory in the double tube water rods can work as the coolant source in the event of total loss of feed water flow. The results of safety analysis show that the safety criteria are satisfied for all selected events.