A conceptual design was performed of a light water moderated reactor with power output in the range of 1000 MWe, which allows passive decay heat removal (i.e., the heat path to the ultimate heat sink, ambient air, is provided by natural heat transfer mechanisms such as conduction, radiation and free convection). This eliminates the reliance on the availability of emergency pumped cooling. The design ensures that the fuel remains within safety limits even in the total absence of coolant in the primary system. The challenge met was the achievement of this passive cooling capability while simultaneously achieving a high, 1000 MWe power rating.