The mPower design was announced by Babcock and Wilcox (B&W) in 2009. Responsibility for the design was transferred in July 2010 to Generation mPower, LLC, which is a partnership of Babcock & Wilcox and Bechtel. The design is a 180 MWe LWR-based integral system. The core consists of 69 traditional 17 X 17 pin array fuel assemblies with an active fuel length of 2.4 m. The fuel is conventional UO2 with an enrichment of less than 5% 235U.

An individual mPower module is intended to be completely factory fabricated using currently available components. Each module is placed within a steel containment dome and has a dedicated turbine-generator power conversion unit. An option is being developed to use air-cooled condensers, which reduces the output to 155 MWe, for use where water resources are restricted. It is also being designed to enhance load-following capabilities for connection to more dynamic grids.

A scaled plant simulator has been constructed and is being used to demonstrate the safety performance of the mPower design. This facility was completed in September 2011 and underwent start-up commissioning in early 2012.

Originally, the reference mPower plant contained four 125 MWe reactor modules to yield a plant size of 500 MWe. In 2011, a number of design changes were made to increase the power rating of each module to 180 MWe and the reference plant became a twin unit with total capacity of 360 MWe. The Tennessee Valley Authority has announced its intent to pursue the construction of up to four mPower modules at the Clinch River site in Oak Ridge, Tennessee. Key parameters and a representative graphic for the mPower design are given in Figure 2.10. [8]

Figure 2.10 mPower (United States) — Generation mPower (B&W/Bechtel).