OPG Celebrates the Early Completion of Darlington Unit 3

September 15, 2023

The second of four OPG refurbished reactors now re-connected to Ontario’s electricity grid

Ontario Power Generation (OPG) has achieved a major milestone by successfully connecting Darlington Nuclear Generating Station’s Unit 3 to Ontario’s electricity grid, 169 days ahead of schedule. This world-class project performance demonstrates OPG’s expertise and commitment to completing the station’s four-unit refurbishment safely, with quality and on budget, by the end of 2026.

Unit 3 is now the second Darlington unit to undergo complete refurbishment and is operating at 100 percent capacity, providing clean, reliable energy for Ontarians during these peak summer months. The early return of Unit 3 will produce an extra 3 terawatt-hours of energy, enough to power 350,000 homes for an entire year. It will also reduce up to 1 megatonne of greenhouse gas emissions, or the equivalent of taking 300,000 cars off the road for an entire year.

Unit 2 was completed in early June 2020. Thanks to the quality of refurbishment work, in the three years since its return to service, Unit 2 has experienced a record 529-day continuous run. This is industry-leading performance for a CANDU reactor post-refurbishment. Overall generation was also 10 plus percent better than target.

Unit 1 refurbishment, expected to be completed mid-2025, is approximately 60 percent complete and is currently in the reassembly phase. Unit 4, the last of Darlington’s four reactors, will come offline shortly to begin its refurbishment.

Once complete, a refurbished Darlington Nuclear Generating Station will provide more than 30 years of carbon-free power. The Refurbishment project, together with the station’s extended operation, will generate approximately $90 billion in economic benefits for Ontario and create an average of 14,200 jobs annually across the province.

Quick Facts


“Through this project, OPG is demonstrating that with detailed planning and preparation, large nuclear projects can be completed not only on-time, but ahead of time and with great quality,” said Ken Hartwick, OPG’s President and CEO. “This would not be possible without the performance, expertise, and commitment from our refurbishment project team, project partners, industry experts, energy professionals, and skilled tradespeople.”

Ken Hartwick, OPG’s President and CEO

“The successful refurbishment of Darlington’s Unit 3 ahead of schedule and on-budget will help power the next major international investment in Ontario, the new homes we are building, and industries as they grow and electrify,” said Todd Smith, Minister of Energy. “It’s also proof that this province can deliver the major energy projects we have planned to Power Ontario’s Growth on-time and on-budget, including building a total of four Small Modular Reactors at Darlington, and beginning pre-development work to site Canada’s first large-scale nuclear build in over three decades.”

Todd Smith, Minister of Energy


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