Bruce Power took unit 5 of the Bruce Nuclear Generating Station in Ontario off-line on November 1, 2026 to begin its Major Component Replacement outage, the rebuild that is meant to add 30 to 35 years to the reactor’s operating life. It is the fourth of the site’s eight units to go through the program, and Bruce Power plans to renew six of the eight. The company calls the outage scheduled and says the unit was shut down safely and successfully.
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The reactor is a CANDU 750B pressurized heavy water unit with a net capacity of 817 MWe that first connected to the grid on December 1, 1984, according to the World Nuclear Association’s reactor entry. Removing that much generation for a multi-year rebuild is a deliberate trade, and Ontario has now made it four times.
Steam generators, pressure tubes and feeder tubes in unit 5
As World Nuclear News reported on November 3, the work involves removing and replacing steam generators, pressure tubes, calandria tubes and feeder tubes. Those are the components that wear out first in a CANDU reactor, and replacing them is what buys the additional three decades. The company has not published a return-to-service date for unit 5 in the material available, and the announcement gives neither a duration nor a cost for this outage.
The last published comparison is unit 3. A separate World Nuclear News report said that reactor was reconnected to the grid on June 3, 2026, more than seven months ahead of a January 2027 target, after an outage that began in March 2023. The same report credited robotic tools on a reactor face, the first time a CANDU reactor had been rebuilt that way, and a record for calandria tube removal that finished 11 days early. By simple subtraction, unit 3 spent roughly three years and three months offline.
Where unit 5 sits in the six-unit renewal queue
Unit 6 went first. It entered its outage in January 2020 and returned to the grid in September 2023. Unit 3 followed and came back this year. Unit 4 began in February 2025 and, Bruce Power says, is running ahead of unit 3’s pace and setting records. Unit 5 is now in the chair, unit 7 is scheduled to start in 2028 and unit 8 in 2030. Units 1 and 2, which were refurbished and returned to service in 2012, are being evaluated by Ontario for a second round of work.
The sequencing matters for the grid because the company is carrying one unit at a time out of service while the others keep generating. Ontario’s Independent Electricity System Operator approved the unit 5 project on April 10, 2025 after verifying that Bruce Power met the terms of a Basis of Estimate to proceed. Its notice said the project was scheduled to begin in 2027 and that Bruce Power plans to renew units 3 through 8 over the next eight years, under a 2015 agreement that set up the long-term life-extension program. The shutdown in November 2026 therefore came earlier than the date in that notice.
The unit 3 return also carried a political message. Chassard said at the time that large-scale nuclear projects in Ontario can be delivered safely and efficiently, and Lecce said critics had claimed the work could not be done again. Unit 3 now stands as the evidence Bruce Power points to when it argues that later outages can come in early, and unit 4, which began in February 2025, is described by the company as running ahead of that pace.
For the grid, the arithmetic is straightforward. Bruce Power plans to renew six of the eight units, which means at any time through the early 2030s at least one reactor on the site is likely to be out for rebuild, with the 2028 start for unit 7 and the 2030 start for unit 8 extending that rolling schedule. Units 1 and 2, back in service since 2012, sit outside the current plan and are only being evaluated by Ontario for a second round.
Ontario’s stated payoff and the quotes from Chassard and Lecce
Eric Chassard, president and chief executive of Bruce Power, said the company’s performance gets better with each outage. Stephen Lecce, Ontario’s Minister of Energy and Mines, said the province’s nuclear advantage is powered by the best workers, engineers and skilled tradespeople in the world. The company puts the benefit of the Bruce program and site operations at about CAD 4 billion (USD 2.9 billion) a year in economic activity, plus 22,000 direct and indirect jobs a year.
Bruce Power’s own site describes the company as generating electricity and producing medical isotopes, and it lists the life-extension program and a separate Bruce C project as flagship initiatives. Neither the company’s home page nor the November announcement gives a project cost for unit 5, so the price of this fourth rebuild remains undisclosed.
The question that decides how the program is judged is the return date. Unit 6 took from January 2020 to September 2023, and unit 3 finished months early after a start in March 2023. A three-year outage on the unit 3 pattern would put unit 5 back on the grid around the end of 2029, though Bruce Power has not published a date. The number to watch is the outage duration the company eventually gives for the 817 MWe unit.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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