The basemat foundation module for Canada’s first small modular reactor (SMR) being built at Darlington, Ontario, has been set into place 35 metres below ground in the excavated reactor building shaft. Ontario in May 2025 approved Ontario Power Generation (OPG) to begin construction of the first of four GE Hitachi BWRX-300 SMRs planned for the Darlington New Nuclear Project after the Canadian Nuclear Safety Commission (CNSC) issued a construction licence. Early site preparation works were carried out from 2022 to early 2024. OPG recently applied to CNSC for a licence to operate the plant with plans for grid connection by the end of 2030.
The basemat weighs some 953 tonnes with a diameter of 37 metres and is the foundation for the integrated reactor building and containment structure. It was fabricated, welded, and assembled before being lifted into place by one of the world’s largest crawler cranes. The module features components made of Diaphragm Plate Steel Composite, an innovative modular steel-concrete material, produced by OPG and its partners, with the help of skilled trades from across Ontario.
The province and federal government are making historic investments in this project, including a CAD2bn ($1.47bn) federal investment through the Canada Growth Fund and a CAD1bn provincial investment through the Building Ontario Fund.
In addition, the Ontario government announced that the SMR supply chain has grown to include more than 100 Canadian companies. As well as more than 80 Ontario companies, including northern and rural suppliers, that have already signed agreements OPG and its partners to deliver the project, 16 new Ontario-based companies, and six companies from Quebec and Alberta have joined the supply chain.
Recently awarded contracts include Walters Group, awarded a CAD44.5m contract for structural steel; Marmon Industrial Water, awarded a CAD17.8m contract for a condensate purification package; Tractel, awarded a CAD9.9m contract for the reactor building weather enclosure; and Hooper Welding, awarded a CAD8.8m contract for sampling and collection tanks.
“Ontario just executed with great precision the first foundation of a new nuclear reactor in Ontario in over 30 years,” Ontario Minister of Energy and Mines Stephen Lecce said. “This is a major achievement as the world turns to Ontario to refurbish and build large scale nuclear on-time and on-budget.” He added that the SMR supply chain is “infusing” more than CAD500m 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% of every dollar in the Canadian supply chain.”
