Nuclear Energy News

Bruce Power’s Unit 4 Refurbishment Beats Schedule as Calandria Tube Installation Wraps Up

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Bruce Power said this week that its Unit 4 Major Component Replacement (MCR) project has finished installing all 480 calandria tubes in the reactor’s core, completing the step 25 days faster than the equivalent work took on Unit 3. The milestone, reported by World Nuclear News on October 15, moves the refurbishment of the 822 MWe CANDU reactor at the Bruce Nuclear Generating Station in Tiverton, Ontario, into its next stage: installation of the unit’s fuel channels.

Calandria tubes are zirconium-alloy (Zircaloy) components that form the outer part of each CANDU fuel channel; they house the pressure tubes that in turn hold the reactor’s fuel. A six-axis robotic tool, built and operated in Canada by Bruce Power together with Shoreline Power Group, ATS Automation and Calian Engineering, inserted a calandria tube insert into each tube and rolled the joint to a precise diameter to create a leak-tight seal, working from both faces of the reactor. Bruce Power attributed the faster pace to lessons carried over from Unit 3, which was the first reactor face on which this robotic system was used.

Part of a six-unit refurbishment programme

Unit 4 is the third of Bruce’s eight CANDU units to go through MCR, a refurbishment that Bruce Power says extends each reactor’s operating life by 30 to 35 years. Units 1 and 2 were refurbished previously; Unit 6 completed its MCR in 2024; and Unit 3 was declared commercially operational on June 12, 2026, seven months ahead of the schedule committed to Ontario’s Independent Electricity System Operator (IESO). Unit 4 went offline for its own MCR outage in February 2025. Units 5, 7 and 8 are still to come, with Unit 5’s outage due to begin in November 2026; Bruce Power’s Life-Extension Program is scheduled to run through all six units by 2033.

The programme, one of the largest infrastructure undertakings in Canada, carries an estimated price tag of roughly CAD 13 billion (about USD 9 billion) across the six units. Bruce Power — a consortium that includes TC Energy, OMERS and the plant’s labour unions — has said the Unit 3 MCR came in about 15% below the cost of the Unit 6 project, with shareholder equity contributions of CAD 1.1 billion; the company expects to return roughly CAD 150 million to Ontario ratepayers through the IESO as a result.

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A faster second pass at an unfamiliar technique

Robotic reactor-face tooling was new to the Bruce programme when it was first deployed on Unit 3, and the 25-day improvement on Unit 4 is Bruce Power’s clearest public evidence yet that the learning curve on that technique is paying off. A similar pattern showed up earlier in the project: in its second-quarter 2026 report, Bruce Power’s partner TC Energy said the consortium had also set a “CANDU refurbishment record” for calandria tube removal — an earlier step in the same process — finishing that stage 11 days ahead of schedule. The same filing credited the station with 98.5% availability for the quarter and no forced outage days.

Why it matters for Ontario’s grid

Ontario’s nuclear fleet, split between Bruce Power and Ontario Power Generation (OPG), supplies roughly half the province’s electricity. OPG is running a parallel refurbishment of its own station under a C$3 billion contract with Aecon to begin refurbishing its Pickering plant, part of the same province-wide push to keep existing reactors running for decades rather than build equivalent new capacity from scratch. Ontario’s Minister of Energy and Mines, Stephen Lecce, said of the Unit 4 progress that “once again, Ontario’s nuclear sector is demonstrating its world leadership,” pointing more broadly to provincial forecasts of electricity demand rising by as much as 90% by 2050 and an estimated 150,000 jobs tied to new nuclear construction in the province.

The milestone also lands in the same week Slovakia connected its newly built Mochovce 4 reactor to the grid, a reminder that new construction and decades-long refurbishment programmes are both advancing in parallel across the nuclear sector this year.

Unit 4’s MCR is not finished. The reactor still needs its 480 fuel channels installed, along with 960 feeder tubes and eight steam generators, before it can be returned to service. Bruce Power has not given a specific target date for Unit 4’s return beyond the broader 2033 completion goal for the full Life-Extension Program.