Project Details
Location
Darlington, Ontario, Canada
Capacity
1,200 MW-electric
COD
Expected COD: 2030
About This Project
Executive Overview
The Darlington Small Modular Reactor project is the first grid-scale SMR deployment in the G7, being constructed by Ontario Power Generation (OPG) at its Darlington Nuclear site in Clarington, Ontario. The project will deploy four GE Hitachi BWRX-300 reactors, each producing 300 MWe, for a total output of 1,200 MW — enough to power approximately 1.2 million homes. OPG received a Licence to Construct from the Canadian Nuclear Safety Commission in April 2025, and a $450 million execution contract was awarded to Candu Energy (an AtkinsRéalis company) in June 2025, with the alliance team including GE Hitachi Nuclear Energy and Aecon Kiewit Nuclear Partners. Unit 1 is targeted for completion by 2030, with the remaining three units expected online between 2034 and 2036. Total project cost for all four units is estimated at $20.9 billion (2024 dollars), with the first unit and shared infrastructure approved at $7.7 billion.
How It Works & Differentiation
The BWRX-300 is a water-cooled, natural circulation boiling water reactor that is approximately 10% the size and complexity of a conventional BWR, achieved through a simplified design that eliminates large-bore recirculation piping and reduces the number of safety systems by relying on passive cooling. GE Hitachi targets a capital cost reduction of up to 60% per MW compared to traditional large nuclear plants, with a construction timeline of 24–36 months per unit. The reactor pressure vessel is being manufactured by BWX Technologies, and fuel will be supplied by a consortium including Cameco (Canada), Urenco USA, Orano (France), and Global Nuclear Fuel-Americas. Darlington is the only site in Canada licensed for new nuclear construction with a completed Environmental Assessment, giving the project a regulatory advantage over any potential competitor sites.
Commercialization & Traction
BWXT Canada has been awarded contracts exceeding C$1 billion for components across both the Darlington SMR and Pickering life-extension projects, creating more than 350 jobs in Cambridge, Ontario and demonstrating the depth of the Canadian nuclear supply chain. The Canada Growth Fund has committed up to $2 billion in equity, and the Building Ontario Fund up to $1 billion, providing public financing alongside OPG's own funds, cash flow, and debt. Cost overrun risk is shared between OPG and the construction alliance partners (GE Hitachi, AtkinsRéalis, Aecon), providing commercial alignment on delivery. The Affordable Energy Act passed by Ontario prioritises nuclear for future electricity demand increases, providing legislative backing for the project's revenue model.
Scalability & Strategic Context
The Darlington fleet approach — four units at one site — is designed to deliver progressive cost reductions, with each successive unit benefiting from first-of-a-kind learning on shared infrastructure. OPG projects that four SMRs will contribute $35.1 billion to Ontario's GDP and sustain 3,700 jobs annually over a 65-year operating lifetime. Ontario has additionally announced plans for up to 4,800 MW of new nuclear at Bruce Nuclear Generating Station and up to 10,000 MW at a proposed Wesleyville site, with Darlington serving as the technical and regulatory template for both. Four Canadian provinces — Ontario, New Brunswick, Saskatchewan, and Alberta — have signed an MOU to advance SMR deployment, positioning Darlington as the reference project for a potential national programme.
Project Timeline
OPG marks new milestones in construction of G7’s first Small Modular Reactor
Further Reading
OPG marks new milestones in construction of G7’s first Small Modular Reactor
Ontario Power Generation (OPG) has achieved new milestones in constructing the G7’s first commercial small modular reactor (SMR) at Darlington, including securing major financing and advancing key construction phases to deliver 300 megawatts of low-carbon power for Ontario by 2030.
Contract awarded for first SMR at Darlington
Ontario Power Generation has awarded a $450 million contract to Candu Energy, an AtkinsRéalis company, to build the first of four planned small modular reactors (SMRs) at the Darlington New Nuclear Project in Ontario, marking the first new nuclear construction in the province in over 30 years and targeting completion by 2030.
GE Vernova and Hitachi Energy’s BWRX-300 Small Modular Reactor Approved for Construction in Ontario by OPG
GE Vernova Hitachi’s BWRX-300 small modular reactor has been approved for construction by the Province of Ontario and Ontario Power Generation, marking the start of the first SMR build in the Western world at OPG's Darlington site.
Canada Approves First Grid-Scale SMR Construction at Darlington
Canada has approved the construction of its first grid-scale small modular reactor (SMR), a 300-MW GE-Hitachi BWRX-300, at Ontario Power Generation’s Darlington site, marking a historic milestone for nuclear energy development in the country.
GE Vernova, Hitachi, and Ontario Power Generation to Build First Small Modular Reactor in the Western World in Canada
GE Vernova Hitachi and Ontario Power Generation have received approval to build the first small modular reactor (SMR) in the Western world at the Darlington nuclear site in Ontario, Canada, marking a major milestone for nuclear innovation and clean energy deployment.
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BWXT Canada awarded major contracts for 2 OPG plants
BWXT Canada has been awarded contracts worth over C$1 billion by Ontario Power Generation to support the Pickering nuclear plant's life extension and manufacture components for the Darlington small modular reactor project, creating 350 new jobs in Ontario.
OPG approved to build first SMR at Darlington nuclear project
The article reports that Ontario Power Generation (OPG) has received approval from the Canadian Nuclear Safety Commission to build the first small modular reactor (SMR), a GE Hitachi BWRX-300, at the Darlington Nuclear site in Ontario, marking a significant step for new nuclear development in Canada.
Ontario Leads the G7 by Building First Small Modular Reactor
The article announces that Ontario is leading the G7 by building the first small modular reactor, marking a significant step in clean energy innovation.
Ontario’s Darlington SMR project to cost nearly $21 billion, significantly higher than previous estimates
Ontario's Darlington small modular reactor (SMR) project is now estimated to cost nearly $21 billion, significantly higher than expected, raising concerns about the economic viability and broader adoption of SMRs.
BWRX-300 Small Modular Reactor at Darlington, Ontario
The page describes Ontario Power Generation's commitment to build four GE Vernova BWRX-300 small modular reactors at the Darlington Nuclear Generating Station, making it the first site in North America to deploy these advanced, carbon-free nuclear units to meet growing electricity demand.
Darlington New Nuclear Project
The Darlington New Nuclear Project is a partnership to build North America’s first grid-scale Small Modular Reactor (SMR), the GE Hitachi BWRX-300, at the Darlington site in Ontario, providing up to 300 megawatts of electricity and supporting sustainability and net-zero goals.
Darlington Small Modular Reactor (SMR) Project
The Darlington SMR project is Ontario Power Generation’s initiative to build and operate up to four grid-scale small modular reactors at the Darlington nuclear site, making it the first commercial SMR project in the G7 and a key step toward providing clean, reliable, carbon-free electricity to support Ontario’s growing energy needs and climate goals.