Canadian Design and Construction Report staff writer
The governments of Ontario and Canada are investing a combined $3 billion to support construction of four small modular reactors (SMRs) at Ontario Power Generation’s (OPG) Darlington New Nuclear Project — the first of their kind in the G7 and North America’s first new nuclear build in more than 30 years.
Ontario is contributing $1 billion through the Building Ontario Fund, while the federal government is providing $2 billion through the Canada Growth Fund. The investment will help deliver 1,200 megawatts of clean, reliable electricity — enough to power 1.2 million homes — and create thousands of jobs across the province.
“Today’s investment to support the first SMRs in the G7 is a down payment on Ontario’s nuclear energy future,” said Premier Doug Ford. “We’re protecting Ontario by supporting good-paying, long-term jobs for Ontario workers and building the energy infrastructure — including both SMRs and new, large-scale nuclear — needed to make Ontario an energy superpower.”
Construction on the first SMR began in May 2025 following approval from the Canadian Nuclear Safety Commission and the Province of Ontario. Once operational in 2030, the first BWRX-300 reactor will produce 300 megawatts of power, forming the foundation of OPG’s planned SMR fleet.
Progress on site continues to ramp up. In July, the project’s massive tunnel boring machine, Harriet Brooks — named after Canada’s first female nuclear physicist — arrived at the Darlington site after months of planning and overseas transport. Each component of the 6.97-metre-wide machine is now safely stored until assembly begins in early 2026. Once operational, Harriet Brooks will bore and line a 3.4-kilometre tunnel for the plant’s condenser cooling water system, a critical part of the reactor’s operation.
Meanwhile, skilled trades from across Ontario are fabricating structural components for the reactor building. Production of diaphragm plate steel composite (DPSC) modules — including the Basemat module that forms the foundation of the reactor — is progressing at offsite facilities, with deliveries now arriving at Darlington. Once the reactor shaft excavation is complete, a heavy crane will lower the Basemat 35 metres into position.
The project’s pre-assembly building and fabrication facility are now complete and ready for use. Foundation work for the radiation waste, control, and service buildings has wrapped up, and excavation continues on the reactor shaft, forebay shaft, and condenser cooling water launch shaft. Site grading for three additional SMR units is also finished.
OPG and its partners are advancing planning and licensing for the remaining three reactors. Once all four SMRs are operational, they will contribute $38.5 billion to Canada’s GDP over 65 years, sustaining an average of 3,700 jobs annually and creating 18,000 jobs during construction. About 80 per cent of project spending will stay in Ontario, supporting more than 80 companies and injecting roughly $500 million a year into the province’s supply chain.
OPG says it is leveraging more than 7,000 lessons from its successful Darlington Refurbishment project to ensure safe, efficient construction and long-term performance for the new SMR fleet.
