Nuclear Energy
Canada Completes $9.4B Darlington Nuclear Plant Rebuild Early, on Budget

Workers involved in the $9.4B refurbishment of Ontario Power Generation's four-unit Darlington nuclear plant, 45 miles of Toronto, gained training on a reactor mockup.
Ontario Power Generation said construction has completed four months early and $110-million under budget on the decade-long, estimated $9.4-billion upgrade of the four-unit Darlington nuclear plant, 45 miles east of Toronto. Final testing is under way on its 878-MW Unit 4 reactor that is set to return to full commercial operation by month's end.
The last project marks completion of what Ontario Power Generation says is the world's largest refurbishment project.
The reactors, all 878-MW each, began commercial operation in the early 1990s—with Unit 2, the first upgraded unit returned to service in June 2020, Unit 3 in July 2023 and Unit 1 in November 2024. The Canada-based project consortium was led by Aecon Group Inc. and AtkinsRéalis, with other key partners ES Fox, Black & McDonald Ltd. and BWXT Canada. According to Ontario Power Generation, work included replacement of 1,920 fuel channels and 3,840 feeder pipes.
“Through this project, we have demonstrated to the world that complex nuclear projects can be completed successfully, ahead of schedule, and under budget." said Nicolle Butcher, Ontario Power Generation president and CEO. "Our experience on this refurbishment, and the thousands of lessons we have learned, will serve as our foundation as we advance nuclear’s future."
The upgrade extends the plant's life to 2055, said Ontario Power Generation.
Last November, Ontario's provincial government also gave the agency formal approval to begin upgrading at the Pickering nuclear station, also near Toronto, four nuclear power units totaling about 2.1 GW and expanding their capacity to about 2.2 GW.
The estimated $19.75-billion project, also awarded to Aecon-ArkinsRealis as EPC contractor set to begin work in 2027, includes replacement of all 48 steam generators, which Ontario Power Generation says is a first-of-its-kind work scope for its Candu reactor fleet. The project also includes construction of a 1.5-km deep-water intake system to secure colder cooling water, described as an infrastructure element not in the original plant design. Four other units have been closed and are set to be decommissioned.
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Ontario Power Generation also gained approvals last spring from the province and the Canadian Nuclear Safety Commission to start construction of the first of four BWRX-300 small modular nuclear reactors at Darlington, awarding a $329-million contract to AtkinsRéalis unit CANDU Energy for the first one set to operate by 2030. When completed and after gaining licenses to begin commercial operation, the 300-MWe boiling water reactors are expected to generate about 1.2 GW of power.
"In a world of uncertainty, our government is doubling down on Canadian nuclear technology and workers, with 96 percent of investment benefiting Ontario’s supply chain," said Stephen Lecce, national minister of energy and mines, "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.”
Japan's Stalled Nuclear Restart Finally Clicks
Meanwhile, on Feb. 9, Japanese nuclear experts at Tokyo Electric Power Co. (TEPCO) restarted a key unit of he world’s largest nuclear power plant—the nearly 8-GW. seven-reactor Kashiwazaka-Kariwa faciity near Tokyo—after suspending an earlier attempt due to a control rod warning. “We will continue to demonstrate our commitment to safety as our priority at the Kashiwazaki-Kariwa Nuclear Power Station through our actions and results,” TEPCO said in a statement.
Japan shut all of its nuclear plants after a March 2011 earthquake and tsunami caused some meltdown of its Fukushima Daiichi facility, also TEPCO-owned. It now is being decommissioned.
The 1.3-GW Kashiwazaka-Kariwa unit is the 15th reactor restarted as Japan aims for carbon neutrality by 2050, and to curtail use of fossil fuels—particularly imported liquefied natural gas. The plant complex now includes a 50-ft-high wall to protect against tsunamis, along with upgraded safety and emergency power systems to meet new stardards set by Japan’s Nuclear Regulation Authority.
The country's prime minister, Sanae Takaichi, who was re-elected in a landslide victory on Feb. 8, sees nuclear power as a long-term domestic energy source and economic engine for the country, aiming for it to supply 20% by 2040. She supports expedited development of next-generation reactors and fusion technology, "The stable and inexpensive supply of energy is absolutely crucial," she said. noting that "domestically-sourced energy, notably nuclear power and perovskite solar cells, will be critical."

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