Critical nuclear reactor shuts down for 35-year life extension as power demand surges

Unit 5 at the Bruce nuclear generating station has been taken offline to begin a comprehensive core rebuild. Technicians safely disconnected the reactor on 1 November, launching its scheduled Major Component Replacement (MCR) outage.

The shutdown marks the official midway point of Bruce Power’s privately financed Life-Extension Program. The multi-billion-dollar project aims to modernize Units 3 through 8 by 2033.

The overhaul will add 30 to 35 years to the operational life of the units. Inside the reactor vault, crews face an intensive mechanical undertaking. Workers must strip out and replace 480 calandria tubes alongside an equal number of pressurized fuel channels.

Teams will also fit 960 feeder tubes and hoist massive new steam generators into place. Once reassembled, the renewed reactor will provide low-carbon baseload electricity alongside a steady supply of cancer-fighting medical isotopes for the international healthcare sector.

To meet rising demand for electricity

The start of work on Unit 5 arrives at a pivotal moment for Canada’s most populous province. Officials project that electricity demand across Ontario will surge by 90 percent by 2050, driven by rapid industrial expansion and widespread electrification.

Project teams are entering Unit 5 with strong momentum after the neighboring Unit 4 outage. In October 2026, engineers on Unit 4 completed the installation of all 480 calandria tubes nearly a month ahead of schedule, setting a site record by outpacing the previous refit by 25 days. Technicians have now moved on to installing the fuel channels.

That pace reflects lessons gathered from earlier phases of the multi-billion-dollar program. Unit 3 returned to commercial service this past June, finishing more than seven months ahead of schedule after teams successfully deployed specialized robotics on the reactor face for the first time.

The early restart provided vital capacity during peak summer demand and delivered roughly $150 million back to Ontario ratepayers through the Independent Electricity System Operator. Unit 6, the first reactor upgraded under the initiative, also wrapped up ahead of schedule and under budget in 2023, returning $52 million to consumers.

Long-term outage schedule

“Extending the life of this critical asset will deliver reliable, affordable electricity, while strengthening Ontario’s position as a global energy superpower that can refurbish nuclear plants on time and on budget,” said Stephen Lecce, Ontario Minister of Energy and Mines. Lecce highlighted that 95 percent of Bruce Power’s spending stays within Canada.

Eric Chassard, Bruce Power’s President and Chief Executive Officer, noted that performance has improved with every successive reactor refit as methods become more refined.

To meet long-term supply targets, Bruce Power will run overlapping reactor outages continuously for the next seven years. Unit 7 will shut down for its upgrade in 2028, with Unit 8 following in 2030. Provincial planners are also evaluating a second major overhaul for Units 1 and 2, which originally returned to service in 2012.

“This work is securing a reliable supply of clean electricity for decades to come and reinforcing our region’s role as a leader in Ontario’s nuclear success story,” concluded Lisa Thompson, MPP for Huron-Bruce.

Source: https://interestingengineering.com/energy/critical-nuclear-reactor-shuts-down