Pickering Nuclear Generating Station B Refurbishment

Ontario Power Generation is rebuilding the middle of four CANDU reactors that have run on the Lake Ontario shoreline since the 1970s. The Ontario government approved the Pickering B refurbishment in January 2025 with a CA$26.8 billion budget, which makes it one of the largest single construction commitments in Canadian history. Units 5, 6, 7 and 8 are in scope, roughly 2,000 MW of baseload capacity.

The work is a full mid-life overhaul: retube, feeder replacement and boiler replacement, all of it inside existing containment. That’s the constraint that defines the job. Nothing can be enlarged, most of it happens in a radiological environment, and the sequence has to be proven before the first tool goes in.

Project Scope

Four reactor units. CA$4.1 billion for the definition phase, with CA$6.2 billion committed to date against the CA$26.8 billion total. Aecon and AtkinsRealis hold a CA$2.1 billion definition-phase joint venture covering engineering, long-lead procurement and construction planning.

The Pickering B units shut down in the third quarter of 2026 to hand the station over to the project. Refurbishment construction is scheduled to start in early 2027, with all four units back in service by the mid-2030s and about 30 additional years of operating life. The Canadian Nuclear Safety Commission regulates the work. Execution-phase construction contracts haven’t been awarded.

Why It Matters

OPG is running the Darlington playbook, where refurbishment finished early and under budget, and the definition phase is where that outcome gets bought. Spending CA$4.1 billion on engineering and planning before construction starts looks expensive until you compare it against the industry’s record on nuclear projects that went to site with an incomplete design.

For the North American nuclear supply chain, four units on a defined schedule is the kind of repeat work that keeps specialist crews and fabricators employed between new-build programs.

Project Team & Details