CLARINGTON, ONT. – The Ontario government has announced a major construction milestone has been reached on the G7’s first Small Modular Reactor (SMR) at Darlington.
A 2.1-million-pound basemat module for the Unit 1 SMR was lifted and installed at the project site recently.
This precision lift was executed by one of the world’s largest crawler cranes, an LR/LE 12500-1.0 crawler crane that has up to 2,500 tons (5.5 million pounds) lifting capacity and more than 200 metres of reach.
It lowered the material within millimetre precision and represents the first foundation of a new nuclear reactor to be built in Ontario in over 30 years, explains a release.
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.
Aecon Kiewit Nuclear Partners, a partnership between Aecon and Kiewit Nuclear Canada, was awarded an alliance construction contract by Ontario Power Generation (OPG) in 2025 for the execution phase on the new nuclear project.
Being executed under an Integrated Project Delivery model, the partners will work with OPG, GE Vernova Hitachi Nuclear Energy and AtkinsRéalis.
The government previously noted the first unit will cost $6.1 billion, along with costs for systems and services common to all four SMRs of $1.6 billion. Costs are expected to decline with each unit as efficiencies are gained, similar to the Darlington Refurbishment Project, a release notes.
In addition to this latest milestone, the government is also announcing 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,” the release adds.
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.
OPG began site preparation for the first SMR in December 2022 and obtained a Licence to Construct for Unit 1 from the Canadian Nuclear Safety Commission in April 2025. OPG filed its Licence to Operate application for Unit 1 to the CNSC in March 2026.
Thus far, the province has invested $1 billion through the Building Ontario Fund for the project, and the federal government has invested $2 billion through the Canada Growth Fund.
