MHI completes EDF replacement steam generators

22 January 2024

Mitsubishi Heavy Industries Ltd (MHI) has marked the completion at its Kobe works of three of the nine replacement steam generators ordered by the French reactor operator.

MHI marked the completion of the steam generators in a ceremony at its Kobe Shipyard & Machinery Works (Image: MHI)

Steam generators transfer the thermal energy generated in the reactor vessel of a pressurised water reactor (PWR) from the primary (reactor) cooling system to the secondary (turbine) cooling system, producing the steam to drive the electricity generation turbine.

The steam generators - each about 21 metres in height and weighing some 330 tonnes - are pressure-resistant vessels made with strong low-alloy steel (steel with not more than 5% alloying element). Each steam generator contains more than 4,500 heat transfer tubes made of TT690 - a state-of-the-art nickel, chromium, and iron alloy, specially heat-treated for enhanced corrosion resistance. High machining accuracy is required in their manufacture - in the order of 0.01 mm - MHI said.

One of the replacement steam generators manufactured by MHI for EDF (Image: MHI)

MHI has now supplied some 31 replacement steam generators for reactors in France, Belgium and the USA. Fifteen of these have been supplied to EDF, which is replacing steam generators at its PWR plants that started operations in the 1980s as part of plans to extend the plants' operating periods beyond 40 years.

MHI was selected to supply the steam generators through an international bidding process and received the order jointly with its long-term collaborator Onet Technologies of Marseilles, France.

Researched and written by World Nuclear News