Supercritical water reactor

The supercritical water reactor (SCWR) is a concept Generation IV reactor, designed as a light water reactor (LWR) that operates at supercritical pressure (i.e. greater than 22.1 megapascals [3,210 psi]). The term critical in this context refers to the critical point of water, and should not be confused with the concept of criticality of the nuclear reactor.

The water heated in the reactor core becomes a supercritical fluid above the critical temperature of 374 °C (705 °F), transitioning from a fluid more resembling liquid water to a fluid more resembling saturated steam (which can be used in a steam turbine), without going through the distinct phase transition of boiling.

The supercritical water reactor combines the established technologies of the supercritical steam generator (typically used to generate electricity from fossil fuels) with the boiling water reactor (BWR), to achieve a design that is simpler and more efficient than a BWR, by operating at a higher pressure. As with a BWR, the turbine and reactor pressure vessel are in the same coolant loop, in contrast to a pressurized water reactor (PWR).

The development of SCWR systems is considered a promising advancement for nuclear power plants because of its high thermal efficiency (~45 % vs. ~33 % for current LWRs) and simpler design. As of 2012 the concept was being investigated by 32 organizations in 13 countries.