Supercritical Water Reactors

Clay Jones
March 25, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017


Fig. 1: Supercritical Water Cooled Reactor. [2] (Courtesy of the DOE.)

As part of the Generation IV initiative, the International Forum chose six proposed nuclear reactor designs to pursue research on. One of these proposed solutions was the design of the Supercritical water cooled reactor. SCWR reactors are very similar to light water reactors, see Fig. 1. "The light water reactor is a type of thermal- neutron reactor that utilizes normal water as opposed to heavy water, a form of water that contains a larger amount of the hydrogen isotope deuterium." [1] The difference between these reactors is that SCWRs perform with much higher pressure and temperature than the light water reactors. This seemingly small difference actually increases the high thermal efficiency from an advanced light water reactor's efficiency of 35% to about a 45% efficiency. [2] Along with the LWRs, SCWRs use similar technology to the super-critical coal-fired boiler with the goal of producing cheap electricity. [2]

Major Components

As the current US design stands, the SCWR will operate with an inlet temperature of about 280°C and an inlet density of about 760 kg/m3. [2] This inlet flow runs between the core barrel and the reactor pressure vessel, two components that I will discuss in this section. The outlet coolant is supposed to decrease its density to about 90 kg/m3 and increase its temperature to roughly 500°C, see Fig. 2. [2] This outlet coolant is what provides the turbine with power to operate.

Fig. 2: The SCWR reactor pressure vessel. [2] (Courtesy of the DOE.)


In this design, there are multiple benefits in terms of cost and efficiency making it a highly sought after goal for the Generation IV International Forum and a clear upgrade from the current light water reactors. Unfortunately, there are still many technological challenges that we must overcome to make this design a reality. Key elements have yet to be developed and tested under realistic conditions, designs for parts have yet to be made, and regulation issues have yet to be resolved, but all in all there is solid progress being made to develop the first supercritical water cooled reactor.

© Clay Jones. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] B. Zarubin, "Introduction To Light Water Reactors," Physics 241, Stanford University, Winter 2015.

[2] J. Buongiorno and P. E. MacDonald, "Supercritical-Water-Cooled Reactor (SCWR)," Idaho National Engineering and Environmental Laboratory, INEEL/EXT-03-01210, September 2003.

[3] M. Greger, "Forging," Technical University of Ostrava, 2014.