en.Wedoany.com Reported - Ontario Power Generation (OPG) is building Canada's first new nuclear unit in over 30 years at the Darlington Nuclear Generating Station, utilizing GE Vernova Hitachi Nuclear Energy's (GVH) BWRX-300 small modular reactor. OPG Chief Project Officer Subo Sinnathamby stated on May 8 that since receiving the final investment decision a year ago, project progress has been rapid, with a construction license obtained and the new reactor's base mat installed.
Located on the north shore of Lake Ontario, about 45 miles east of Toronto, Darlington currently operates four 878 MWe pressurized heavy water reactors. OPG plans to add four BWRX-300 modules, which will be Canada's first non-PHWR power reactors. Sinnathamby, who has 25 years of experience in nuclear operations and projects at OPG, previously led the major refurbishment of the Darlington CANDU reactors, a project completed under budget and ahead of schedule. The Darlington New Nuclear Project (DNNP) she now oversees serves as a significant test case for both Canada and the United States.
Sean Sexstone, Executive Vice President of Advanced Nuclear Energy at GVH, stated that the company is working closely with OPG and suppliers to deliver the BWRX-300 at Darlington and other proposed sites. Having worked on projects like Vogtle, he noted that "it's been a long time since new nuclear was built," and demand is currently strong.
The refurbishment project laid the foundation for new construction. The C$12.8 billion Darlington refurbishment completed all four units within a decade, which Sinnathamby described as "an extraordinary experience." Key success factors included processes and tools, a "one team" culture with suppliers, construction training mockups, and pre-procurement of major components. Full-scale mockups played a crucial role in the first unit, enabling a "rinse and repeat" approach for subsequent units.
Regarding the supply chain, Sexstone noted that the "X" in BWRX-300 represents the 10th generation, with GE having built 67 boiling water reactors and Hitachi possessing extensive ABWR construction experience. Key suppliers for DNNP include Aecon Kiewit Nuclear Partners (a joint venture of Aecon and Kiewit), AtkinsRéalis, BWXT Canada, and Velan Valves, with over 100 companies in Ontario involved in the supply chain. Approximately 80% of the supply chain is located in Ontario, though components like turbines need to be sourced externally. Fuel for the BWRX-300 will be manufactured by GVH's Global Nuclear Fuel, with uranium sourced from Canada's Cameco mines and enrichment to be conducted in the United States or Europe. GVH plans to invest approximately C$70 million to establish a BWRX-300 Engineering Service Center near the Darlington site.
The "one team" approach OPG established for the refurbishment project will be reused for DNNP. Leveraging the skilled workforce developed through the refurbishment, some personnel have already transitioned to the SMR project. The Canadian Nuclear Association's 2026 conference noted that the project creates 19,000 direct and indirect jobs in Ontario, with the DNNP site workforce peaking at approximately 2,000 people.
In terms of cost and schedule, OPG, through lessons learned, achieved a one-year reduction in construction duration and significant cost savings for the last unit of the refurbishment project compared to the first. The DNNP project envelope is C$20.9 billion, with C$7.7 billion already released for common systems and the first unit, including approximately C$1.6 billion for common systems (cooling water intake, administration building, etc.) and C$6.1 billion for the first unit. Costs for subsequent units are expected to decrease from approximately C$5 billion to around C$4 billion for the last unit.
On April 22, the base mat, weighing approximately 2.1 million pounds and measuring 37 meters in diameter, was successfully lifted and placed into the reactor shaft. The base mat uses a composite diaphragm steel plate material, not traditional reinforced concrete. Sexstone noted that the assembly of the base mat provides clear lessons for subsequent modular work. GVH already has teams working ahead on units 2 through 4, reviewing lessons learned and optimizing schedule and costs.
Next steps on site include constructing the turbine building and building the modules for the first floor of the reactor building. The first floor alone will consist of over 200 modules, with the reactor building totaling approximately 1,200 modules. The next major milestone is expected to be the completion of the first floor by the end of 2026. OPG faces two additional regulatory hold points, involving the installation of the reactor pressure vessel and non-fuel commissioning. OPG has submitted an operating license application, aiming to complete construction by the end of this decade and achieve grid connection by the end of 2030.
Regarding future BWRX-300 deployments, Sexstone stated that the primary focus remains on Darlington. Saskatchewan's SaskPower has also announced its intention to build. In the United States, nuclear projects are attracting attention; in Poland, GVH is partnering with Orlen Synthos Green Energy; and in Sweden, GVH has been shortlisted for Vattenfall's small modular reactor project. Sexstone believes that achieving gigawatt-scale solutions through configurations of four or five SMRs will be more economical in the long term.
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