To meet anticipated growth demand, Ontario Power Generation (OPG) committed to build the first four GE Vernova small modular reactors (SMRs) in North America.

The challenge

Licensing restrictions have limited construction of new nuclear facilities in Canada. The Darlington Nuclear Generating Station in Ontario remains the only site in the country where new construction is possible. Because the site already houses a functioning four-unit facility, space for new construction is limited.

The solution

OPG contracted with GE Vernova to build four of its BWRX-300 small modular reactors (SMRs) at the Darlington New Nuclear Project site. When constructed, each unit will deliver enough electricity to power 300,000 Toronto homes and is 10% the size and complexity of even a traditional boiling water reactor (BWR).


The Ontario supply chain has embraced the BWRX-300 project and we are encouraged by the leadership we have seen to meet manufacturing quality and schedule requirements to support this project and our integrated team.

Sean Sexstone

Executive Vice President, Advanced Nuclear, GE Vernova


On the northern shore of Lake Ontario east of Toronto, sits the Darlington Nuclear Generating Station. Sporting four Canada Deuterium Uranium (CANDU) pressurized water reactors (PWRs), Darlington is touted as the second largest such facility in Canada. It was originally constructed to meet its initial developer Ontario Hydro’s aggressive linear 7% annual electricity demand growth estimates of the 1970s for power generation.

While those original estimates have moderated somewhat in the intervening years, the facility’s current owners Ontario Power Generation (OPG) still expect to add more generating capacity to the Darlington facility because it remains the only Canadian site cleared by the Canadian Nuclear Safety Commission (CNSC) for any new construction.

OPG began efforts to expand its generating facilities in earnest in 2020 with plans to build one small modular reactor (SMR) at the site and have it operating by at least 2028. Those plans took shape with the first groundbreaking in December 2022, followed by the signing of a contract for deploying a single GE Vernova BWRX-300 SMR at Darlington in January 2023.

Because of GE Vernova’s long history working with Canada’s nuclear program—dating back to the 1950s and development of the basis for all of Canada’s nuclear fleet—in July 2023, OPG announced that it plans to build three additional BWRX-300 reactors at Darlington. When completed, Darlington will boast the first BWRX-300s in North America.

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