Friday, May 1, 2026
Construction on the G7’s first Small Modular Reactor (SMR) at Ontario Power Generation’s Darlington site reached a major milestone with the installation of the 2.1-million-pound Basemat.
On April 22, a heavy crawler crane lifted the 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 complete, the Darlington New Nuclear Project’s four SMRs will produce 1,200 megawatts (MW) of electricity, enough to power 1.2 million homes.
“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,” said Stephen Lecce, Minister of Energy and Mines.
The Darlington New Nuclear Project is No. 2 on ReNew Canada’s 2026 Top100 Projects report.
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.
“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.
The OPG 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.”
Featured image: The Basemat foundation is lowered into the reactor shaft at the Darlington New Nuclear Project site. (OPG)
