Steam Turbines at Genkai-3 and -4 to Be Upgraded

On December 13, Japan’s Kyushu Electric Power Co. announced that it would replace the steam turbines at its Genkai-3 and -4 Nuclear Power Plants (PWRs, 1,180MWe each) with new turbines of advanced design and improved materials and structures. The power company has already submitted applications to Japan’s Nuclear Regulation Authority (NRA) for the approval of the new designs and work plans.

A steam generator (SG) comprises one high-pressure turbine and three low-pressure turbines. The upgrading work will be done at Unit 3 in FY27 (April 2027 to March 2028) and Unit 4 in FY28 (April 2028 to March 2029). Kyushu Electric said that the replacements would “improve reliability and generation efficiency.”

Kyushu Electric Power placed its order for the SG replacement work with Mitsubishi Heavy Industries (MHI), whose Takasago Machinery Works in Hyogo Prefecture will design, manufacture, and complete the work at the site. According to the company’s announcement steam turbines to be delivered will include 54-inch blades that the company itself has designed and developed.

As a PWR plant manufacturer, MHI has demonstrated its superior technological capabilities both domestically and internationally. Already, MHI has delivered four such units in Japan and five overseas. In January 2024, it finished the production of SGs for three units to be used by Électricité de France S.A. (EDF) in France, and will eventually supply nine SGs to that company. The processing precision needed for the part was on the order of 0.01mm.

Since entering service, Genkai-3 has operated for 30 years and Genkai-4 for 27 years. Genkai-3’s long-term facility management plan is now being examined by the NRA as a requirement for the unit to continue operation beyond 30 years, under standards for aging reactors that will fully come into effect in June 2025 as part of a new bundle of legislation known collectively as the Green Transformation (GX) Decarbonization Power Supply Bill.

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