Ontario Delivers Darlington Refurbishment Project Ahead of Schedule and Under Budget
Darlington refurbishment project finishes four months early and $150 million under budget
CLARINGTON — Ontario has completed the refurbishment of the Darlington Unit 4 nuclear reactor four months ahead of schedule and $150 million under budget, marking the conclusion of the world’s largest completed nuclear refurbishment project, the province announced Monday.
The milestone was confirmed by Stephen Lecce, Minister of Energy and Mines, who said the refurbished unit has received approval from the Canadian Nuclear Safety Commission (CNSC) to enter initial power testing beginning February 12, with full power expected shortly afterward.
Originally scheduled to return to service in August 2026, Unit 4’s early completion brings all four refurbished Darlington reactor units back online, extending the station’s operating life to at least 2055.
Powering Ontario for the Next 30 Years
With all four units refurbished, the Darlington Nuclear Generating Station will deliver more than 3,500 megawatts (MW) of clean, emission-free electricity — enough to power 3.5 million homes — for at least the next three decades.
According to the province, refurbishment and continued operations at Darlington are expected to generate up to $90 billion in economic benefits, support approximately 14,200 jobs, and provide long-term energy reliability as Ontario’s electricity demand continues to rise.
Nuclear energy currently supplies about 50 per cent of Ontario’s electricity, making it the backbone of one of the cleanest power grids in the world.
History in the making as we completed the world’s largest nuclear refurbishment, ahead of schedule and $150M under budget.
A big win for Ontario, with 96% of the Darlington refurbishment #MADEINCANADA 🇨🇦 pic.twitter.com/Rmdnc7U7KV
— Stephen Lecce (@Sflecce) February 2, 2026
Economic Impact and Ontario Workforce
The decade-long refurbishment project employed more than 6,000 Ontario workers, including skilled tradespeople, engineers, project managers, and support staff. During construction, the project contributed an estimated $14.9 billion to Ontario’s GDP, with 96 per cent of spending retained within the province.
The province said that for every dollar invested, Ontario’s GDP increased by an average of $1.30, reinforcing the role of nuclear energy as a major economic driver.
Ontario Power Generation (OPG) also documented approximately 8,000 lessons learned during the refurbishment, which will be applied to future nuclear projects, including the upcoming Pickering Nuclear Generating Station refurbishment and new nuclear development across the province.
Nuclear Energy and Ontario’s Long-Term Energy Plan
The Darlington refurbishment is a central pillar of Energy for Generations, Ontario’s first-ever integrated long-term energy plan, aimed at powering housing growth, advanced manufacturing, and expanding communities while maintaining grid reliability.
Ontario is currently home to:
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Three nuclear generating stations
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The G7’s first grid-scale Small Modular Reactor (SMR) under construction at Darlington
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One of the world’s most advanced nuclear supply chains
In September 2025, the CNSC granted OPG a 20-year operating licence for Darlington, authorizing operations until November 30, 2045, the longest nuclear operating licence issued in Canada to date.
Local and Global Significance
Provincial and municipal leaders described the project as a rare international achievement, noting that nuclear refurbishments globally often face cost overruns and delays.
The completion of Darlington Unit 4 ahead of schedule positions Ontario as a global leader in nuclear refurbishment and strengthens the province’s ability to meet growing electricity demand while maintaining clean, reliable power.
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