TOKYO, Jan 22, 2024 – (JCN Newswire via – Mitsubishi Heavy Industries, Ltd. (MHI) held a ceremony for shop manufacturing completion of three replacement steam generators for Électricité de France S.A. (EDF)’s Nuclear Power Plant in France at MHI’s Kobe facilities on the 19th. MHI has been ordered a total of 9 replacement steam generators from EDF. MHI is going to manufacture remaining 6 steam generators.

EDF selected the supplier for the replacement steam generators (for the 900 MWe pressurized water reactor (PWR) nuclear power plant) through an international bidding process, with MHI receiving the order jointly with Onet Technologies (Onet) (Note1).They are approximately 21 meters in height and 330 tons in weight and made of low-alloy steel (Note2). Each steam generator contains more than 4,500 heat transfer tubes made from TT690 alloy material (Note3). Steam generators are one of the most important components of a PWR, transferring the thermal energy generated in the reactor vessel from the primary (reactor) cooling system to the secondary (turbine) cooling system, using steam to drive the turbine. Steam generator is a large component that requires notably safety and reliability and that requires high machining accuracy in the order of 0.01mm. Therefore, manufacturing of steam generator requires quite high capability of design and manufacturing.

MHI has been working on business of nuclear equipment in nuclear power markets worldwide and has supplied a total of 31 replacement steam generators to several countries, France, Belgium and the U.S, 15 units out of 31 units were for EDF. Headquartered in Paris, EDF is one of the world’s largest electricity suppliers, operating 56 PWRs in France. Considering operation extension over 40 years along with French government policy, the company is currently replacing the existing steam generators at its PWR plants that started operations in the 1980s.

From the point of view of carbon neutrality and energy security, there has been a rise in demand for utilization of nuclear power around the world. MHI will continue to contribute to the safety and reliability of nuclear power around the world by delivering high-quality products to global nuclear markets such as France. Through the manufacture of replacement steam generators, MHI will pass on to the next generation the technological expertise accumulated as a nuclear power plant supplier.

(1) Onet is headquartered in Marseille, and provides specialized after-sales service and maintenance for nuclear power plant facilities. MHI has been collaborating with Onet since 2002.
(2) Low-alloy steel is steel with not more than 5% alloying element. Steam generators are pressure resistant vessels made with strong low-alloy steel (manganese, molybdenum, and nickel steel).
(3) TT690 is a state-of-the-art nickel, chromium, and iron alloy, specially heat-treated for enhanced corrosion resistance. It is the main material in the steam generator’s heat transfer tubes, offering superior corrosion resistance under high temperatures and pressures.

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

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