ONTARIO-The Ontario government says the Darlington Unit 4 nuclear reactor is now complete and will be returning to service four months ahead of schedule.
Officials say the overall refurbishment project also came in $150 million under budget. Originally expected to return to power in August 2026, the unit has received approval from the Canadian Nuclear Safety Commission to enter the initial power testing, which is expected to begin on February 12, and will be at full power shortly after. Refurbishment and continued operations over the next 30 years at Darlington is expected to generate up to $90 billion in economic benefits for Ontario, support approximately 14,200 jobs and produce enough clean electricity to power 3.5 million homes.
“Ontario is proving to the world that we can deliver major nuclear energy projects on-time and on-budget,” said Stephen Lecce, Minister of Energy and Mines. “Last year we returned another refurbished unit at Darlington four months ahead of schedule, and today we’ve done it again. Completing the full Darlington refurbishment on-time and under-budget is a made-in-Canada win for our economy, generating $90 billion in economic benefits and supporting 14,200 good-paying jobs. In a world of uncertainty, our government is doubling down on Canadian nuclear technology and workers, with 96 per cent of investment benefiting Ontario’s supply chain. It is a tremendous industrial advantage that Canada is among only six nations that own civilian nuclear technology, yet we stand alone as number one in building, operating, and refurbishing projects on-time and on-budget.”
The Darlington refurbishment project involved the complete overhaul of all four nuclear reactor units, extending the station’s operating life to at least 2055. With all four units refurbished and ready to be brought back online, this marks the completion of the world’s largest refurbishment project to-date, with the Darlington Nuclear Generating Station ready to deliver more than 3,500 megawatts (MW) of clean, reliable, emission-free electricity — enough to power 3.5 million homes — for at least 30 more years.
Over 6,000 Ontario workers were involved in the refurbishmment including skilled tradespeople, support services workers and project managers. Refurbishment work included replacing thousands of fuel channels, feeder tubes, calandria tubes, and end fittings, as well as rehabilitating other critical components. The project also included system improvements and plant upgrades to meet current regulatory requirements. During the construction phase, the project contributed an estimated $14.9 billion to Ontario’s GDP, with 96 per cent of project spending retained in the province. For every dollar invested, Ontario’s GDP increased by an average of $1.30 according to officials.
Ontario is home to the first grid-scale small modular reactor (SMR) under construction in the G7, as well as three nuclear generating stations.
“Bringing the Darlington refurbishment in ahead of schedule and under budget will clearly demonstrate our team’s ability to deliver large and complex nuclear projects,” said Nicolle Butcher, President and CEO, Ontario Power Generation. “The skills we developed and lessons we learned during this project are invaluable as we proceed with refurbishing Pickering Nuclear Generating Station, continue construction on the G7’s first Small Modular Reactor at the Darlington New Nuclear Project, and study the potential for up to 10,000 MW of new nuclear at Wesleyville.”
Nuclear power currently provides about 50 per cent of Ontario’s electricity supply and has positioned Ontario as one of the cleanest electricity grids in the world.
