Press Information

Completion of Conceptual design for Integrated Small Reactor
-- Move to business feasibility for "Social Implementation" Based on Market Needs --


・ Incorporation of primary components inside the reactor vessel for an integrated and simplified design with a high degree of safety
・ Along with power supplies, explore multipurpose use such as motive power or heat source

Tokyo, December 3, 2020 - Mitsubishi Heavy Industries, Ltd. (MHI) has completed the conceptual design for an integrated small reactor to meet a wide range of needs as a carbon-free power source for the future. The incorporation of primary components inside the reactor vessel creates an integrated and compact systems that utilizes technology and expertise with pressurized water reactors (PWRs) to deliver the high degree of safety characteristic of a small reactor.

The reactor can be used for power generation for small grids (300MW class) and for ship-mounted mobile and emergency power supplies for remote islands (30 MW class). In addition to power supplies, it can be used for multi purposes use such as motive power and heat source use.
Based on a multifaceted review and analysis of market needs for this wide range of purposes, MHI will pursue a path to "social implementation," utilizing this success to help provide solutions to real issues facing society.

To date, MHI has been involved with the design, fabrication, construction, and maintenance of 24 PWRs in Japan, working to develop technology to enhance safety, reliability, and long-termoperation, and developing a wide range of innovative nuclear power technologies including small reactors. The development of small reactors began with the reactor for the nuclear-powered ship Mutsu launched in 1969. In the 2000s, MHI began development of a small integrated module reactor (IMR), and through coolant thermal flow testing inside the reactor, and safety system heat removal tests, demonstrated the underlying technology necessary for development. Building on this development knowledge, in recent years MHI has worked to develop small reactors in collaboration with Japanese universities and research institutions with world-leading technologies.

Nuclear power generation is a carbon-free power source capable of providing a large-scale, stable power supply, and is expected to be an important source of baseload power to achieve a decarbonizedsociety. MHI Group, to continue contributing to a stable power supply, is pursuing development of next-generation PWRs with drastically improved safety, and looking ahead, in addition to small reactors is developing future types of reactors such as high-temperature gas-cooled reactors and micro reactors. Going forward, MHI will contribute to society with nuclear power technologies to meet diverse and varied needs.

About MHI Group

Mitsubishi Heavy Industries (MHI) Group is one of the world’s leading industrial groups, spanning energy, smart infrastructure, industrial machinery, aerospace and defense. MHI Group combines cutting-edge technology with deep experience to deliver innovative, integrated solutions that help to realize a carbon neutral world, improve the quality of life and ensure a safer world. For more information, please visit or follow our insights and stories on