A major milestone has been reached in Durham Region as the final refurbished reactor at the Darlington Nuclear Generating Station in Clarington has officially returned to service. The achievement marks the successful completion of a massive 10-year refurbishment project that has upgraded all four reactors at the facility.
Ontario Power Generation (OPG) confirmed that Unit 4 was reconnected to the grid on March 13, 2026, after being offline since July 2023 for refurbishment. This final step completes one of the largest clean energy infrastructure projects in Canada, ensuring the Darlington site will continue producing reliable electricity for decades to come.
The refurbishment project, which began in 2016, focused on modernizing aging infrastructure and extending the life of the reactors. The completion of all four units represents a significant boost to Ontario’s energy supply, especially as demand continues to grow across the province, including in Durham Region.
Local leaders have praised the achievement, highlighting both its scale and efficiency. Clarington Mayor Adrian Foster described the project as a “remarkable accomplishment,” noting that it was completed 142 days ahead of schedule and $150 million under the original $12.8-billion budget. He also recognized the thousands of workers, engineers and technical experts who contributed to the project’s success.
The Darlington facility plays a critical role in Ontario’s electricity system, providing a stable and low-emission source of power. With all four reactors now fully operational, the plant will continue to supply energy to millions of homes and businesses across the province.
Beyond the refurbishment, the Darlington site is also set to play a key role in the future of nuclear energy in Canada. Ontario Power Generation is moving forward with plans to build small modular reactors (SMRs) at the site—an emerging technology that offers a more flexible and cost-effective approach to nuclear power generation.
The approved SMR project includes four new units, which are expected to generate a combined 1,200 megawatts of electricity, enough to power approximately 1.2 million homes. The first unit is scheduled to come online by 2030, with the remaining units expected to follow by 2035.
This development further strengthens Durham Region’s position as a key energy hub in Ontario, supporting both current electricity needs and future innovation in clean energy.
For residents in Clarington and across Durham Region, the completion of the Darlington refurbishment project represents not only a technical achievement but also a source of local pride. The project has created jobs, supported economic growth and reinforced the region’s importance in Canada’s energy landscape.
