Water-Cooled Reactor uses supercritical water as the working fluid. This means that the fluid's temperature and pressure are above its thermodynamic critical point, the point at which the temperature and pressure of the gas and liquid phases are the same. The reactor can operate at high temperatures and pressures without a phase change between liquid and vapor occurring in the coolant, leading to increased thermal efficiency. Uranium oxide is used as fuel and passive safety features, which rely on phenomena such as natural circulation and gravity, which are present in the event of an accident. The main goal of the system is to generate efficient electricity at low cost.