A CATHENA model of the Canadian SCWR concept for safety analysis

The Supercritical Water-Cooled Reactor (SCWR) is one of six reactor concepts under development in the Generation-IV International Forum (GIF). As a member of GIF, Canada is developing a pressure-tube type SCWR, which has the potential to fulfill all major GIF goals on enhanced safety, sustainability, economics, and proliferation resistance. The Canadian SCWR concept employs light water as coolant and heavy water as moderator. High-pressure supercritical water (at 25 MPa and 625^oC) from the reactor core is directly fed into the turbines; this results in higher thermodynamic efficiency than the current fleet of nuclear reactors and also eliminates the need for steam generators. The Canadian SCWR concept is equipped with safety features that enable passive decay heat removal achieving potentially 'no-core-melt' condition under postulated accident scenarios. The system thermalhydraulics code CATHENA will be used in the safety analyses for the Canadian SCWR. Based on the current conceptual design of the Canadian SCWR, a CATHENA idealization has been developed. This model includes all 336 fuel channels with a detailed model of heat transfer in the reactor core. Also modeled are the main pumps, inlet plenum, outlet plenum, turbines, and heavy water moderator. In this paper, the CATHENA idealization of the Canadian SCWR conceptual design is described. Simulation results for steady-state normal operations are also presented for the current Canadian SCWR conceptual design. (author)