Laying the Foundation for the G7’s first Small Modular Reactor
April 30, 2026
At the Darlington New Nuclear Project site, OPG has safely completed a monumental lift for the construction of the G7’s first SMR.
- OPG and its project partners successfully lifted a key foundation piece for the G7’s first Small Modular Reactor (SMR).
- The massive Basemat module will serve as the foundation of the reactor building.
- OPG continues to progress construction of the first SMR unit at Darlington Nuclear.
On April 22, a heavy crawler crane lifted the close to 2.1-million-pound Basemat module, which serves as the foundation of the reactor building, into the newly excavated reactor building shaft, 35 metres below ground.
With a diameter of 37 metres, the Basemat is the common foundation for the integrated reactor building and containment structure.
Once completed, OPG’s planned fleet of four BWRX-300 SMRs will produce enough low-carbon, reliable electricity to power about 1.2 million homes.
It’s the first time in Canada a foundation for a reactor building was assembled modularly – putting the “M” in SMR – as the giant component was fabricated, welded, and put together in one piece before being lifted into place.
Key to its construction were components made of Diaphragm Plate Steel Composite, an innovative and ground-breaking modular steel-concrete material. OPG and its partners, with the help of skilled trades from across Ontario, produced these modules.
With the foundation set down, the project team will now look to build up the first SMR unit – Canada’s first new nuclear build in more than 30 years.
Reaching these milestones speaks to the momentum we’re building from the way we work together.
Boris Vulanovic
Senior Vice President of SMR Execution, OPG
Milestones keep coming
Already, it’s been a busy year full of important milestones achieved for the DNNP.
The project team has completed all shaft excavation work. Two shafts will support the construction of the deep-water intake serving all four planned SMRs. The third provides the foundation for the first SMR.
Additionally, the project recently completed two warehouse facilities, providing the equivalent of one-and-a-half football fields of storage and laydown space for materials.
In late March, OPG also submitted its application for a Licence to Operate the first SMR unit to the Canadian Nuclear Safety Commission, marking a significant milestone for the project.
“Reaching these milestones speaks to the momentum we’re building from the way we work together,” said Boris Vulanovic, OPG’s Senior Vice President of SMR Execution. “Our continued focus on safety, quality and continuous improvement ensures the project is moving forward, and positions us well for the next phase of work.”
From the Ontario Government Press Release:
“Ontario is building the Western World’s first Small Modular Reactor — creating 18,000 good-paying jobs,” said Stephen Lecce, Minister of Energy and Mines. “Ontario just executed with great precision the first foundation of a new nuclear reactor in Ontario in over 30 years. This is a major achievement as the world turns to Ontario to refurbish and build large scale nuclear on-time and on-budget. For the first time, Ontario has secured over 100 Ontario-based businesses to help build the components for SMRs, infusing over $500 million into Ontario’s economy. Our government is deeply committed to building more in Canada, which is why we are proud to invest at least 80 per cent of every dollar in the Canadian supply chain.”
In addition, the government is announcing that more than 100 Canadian companies have signed onto the SMR supply chain. Building on the more than 80 northern and rural Ontario companies that have already signed agreements with Ontario Power Generation and its partners to deliver this first-of-its-kind project, sixteen new Ontario-based companies, and six companies from Quebec and Alberta have joined the supply chain to support the SMR builds. Recently awarded contracts include:
- Walters Group, based in Hamilton, has been awarded a $44.5 million contract for structural steel.
- Marmon Industrial Water, based in Toronto, has been awarded a $17.8 million contract for a condensate purification package.
- Tractel, based in Scarborough, has been awarded a $9.9 million contract for the reactor building weather enclosure.
- Hooper Welding, based in Oakville, has been awarded an $8.8 million contract for sampling and collection tanks.
The construction, operation and maintenance of the four units will add $38.5 billion to Canada’s GDP over the next 65 years. The government has worked with Ontario Power Generation to ensure that 80 per cent of project spending goes to Ontario companies and that construction and operations will protect Ontario workers and jobs by sustaining an estimated 3,800 highly-skilled, good-paying jobs for the next 65 years.
“With the foundation of the first Small Modular Reactor at the Darlington New Nuclear Project in place, we are now able to begin building up, with the project team now advancing construction on the reactor building’s structure, internal systems and components,” said Nicolle Butcher, OPG President and CEO. “This was a milestone months in the making, requiring significant attention to detail and safety, as well as the hard work of dedicated trades and project partners from across Ontario.” Within Canada, the Ontario government and OPG are collaborating with power companies in Alberta, Saskatchewan, New Brunswick, Yukon and Nova Scotia as they work towards the potential deployment of SMRs in their jurisdictions. Around the world, the government has helped secure job-creating agreements that deploy made-in-Ontario components to build SMRs for the world.
SMRs play a central role in Energy for Generations, the government’s first-ever integrated energy plan to ensure Ontario has the reliable, affordable power it needs to power new homes and drive economic growth.
Quick Facts
- In 2025, the Ontario government approved OPG’s plan to begin construction on the first of four SMRs at the Darlington nuclear site.
- During project development OPG will continue to build respectful, collaborative relationships with the communities of the Williams Treaties First Nations, while pursuing potential opportunities for their equity partnership in the project. This would be a first-of-its-kind partnership in Canada for nuclear energy generation, reflecting the government and OPG’s commitment to ensure local First Nations benefit from new projects in their territories.
- The LR/LE 12500-1.0 crawler crane has up to 2,500 tons (5.5 million pounds) lifting capacity and more than 200 metres of reach.
- Once complete, the Darlington New Nuclear Projects four SMRs will produce 1,200 megawatts (MW) of electricity, enough to power 1.2 million homes.
- The province and federal government are making historic investments in this nation-building project, including a $1 billion provincial investment through the Building Ontario Fund and a $2 billion federal investment through the Canada Growth Fund.
- OPG began site preparation for the first SMR in December 2022. Ontario announced that OPG would begin planning and licensing for three additional SMRs, for a total of four SMRs at the Darlington nuclear site in July 2023. OPG obtained a Licence to Construct (LTC) for Unit 1 from the Canadian Nuclear Safety Commission (CNSC) in April 2025. OPG filed its Licence to Operate (LTO) application for Unit 1 to the CNSC in March 2026.
