Bruce Power has started its scheduled Unit 5 Major Component Replacement (MCR) outage.
“We’re essentially rebuilding the entire reactor aside from the concrete structure,” says Maggie Tieman, director of community and external affairs at Bruce Power.
Bruce Power has already renewed Units 6 and 3, which are operating with strong performance, while Unit 4 is setting records in its MCR outage.
This represents the second half of the company’s privately backed MCR project, which will see Units 3 to 8 renewed to provide clean, reliable energy for Ontario’s people, businesses and hospitals for decades to come, while also ensuring a dependable source of cancer-fighting medical isotopes for the global health-care community.
Bruce Power’s first MCR outage in Unit 6 was completed ahead of schedule and under budget in 2023, with $52 million delivered back to Ontario ratepayers. Since then, the renewed Unit 6 has shown excellent performance in powering the province.
Unit 3 was brought back online in June – more than seven months ahead of schedule – returning approximately $150 million to Ontario ratepayers through the Independent Electricity System Operator (IESO).
Unit 4’s MCR outage began in 2025 and is tracking ahead of the timeline set by Unit 3, which was the first to employ innovative robotics on a nuclear reactor.
“We are taking lessons from each MCR; we have developed some innovations to make sure that we’re continuing to complete the refurbishments in the best interest of the repair,” says Tieman. “Unit 3 was the first instance where we used robotics and automation, which has really improved our performance unit over unit.”
Bruce Power and its partners have leveraged lessons from each MCR and developed state-of-the-art technology to better their performance in each successive outage, bringing reliable units back online and passing savings on to ratepayers.
With the start of the Unit 5 project on Nov. 1, overlapping MCR outages will continue at the Bruce site until 2033. Unit 7’s MCR is scheduled to begin in 2028, with Unit 8 scheduled for 2030. Ontario is also evaluating a second MCR for Units 1 and 2, which were refurbished and returned to service in 2012 after being laid up in the late 1990s.