OPG Says Canada’s First Small Modular Reactor Will Miss 2030 Target, Launches Cost Review

Ontario Power Generation (OPG) has confirmed that the first of four small modular reactors (SMRs) planned for its Darlington site will not meet the October 2030 commercial operation date the utility had previously disclosed, as the provincially owned company launches a full review of the project’s cost and schedule.

The disclosure came in OPG’s 2026 third-quarter financial results. The utility said it has identified risks affecting the budget and timeline of Unit 1 of the Darlington New Nuclear Project (DNNP) and is carrying out what it calls a “comprehensive assessment” of the unit’s cost and schedule. That review is expected to be substantially complete by mid-2027, OPG said, meaning Ontario’s government and ratepayers face at least several more months without a firm new completion date.

A Second Slip for Canada’s First SMR Build

The Darlington project is the first commercial deployment anywhere of GE Vernova Hitachi Nuclear Energy’s BWRX-300 small modular reactor design, and construction of Unit 1 began in 2022, making it the first SMR under construction in a G7 country. The site plan calls for four 300 MWe units in total, to be built in sequence rather than simultaneously.

October 2030 was already a later date than OPG’s original planning basis. A 2024 project charter had targeted construction completion by the end of 2028 and commercial availability by the end of 2029, according to OPG filings. The October 2030 date reviewed in the latest results therefore represented one slip already; OPG’s Q3 statement confirms that even that revised date is no longer achievable.

Despite the setback, OPG maintains that the BWRX-300 programme “remains central” to Ontario’s long-term electricity plan, according to the company’s own characterisation of the project in its results commentary, as reported by NucNet. The remaining three Darlington units are still expected to follow in the mid-2030s, though their individual schedules will depend on what the Unit 1 review finds.

What the Cost and Schedule Review Covers

OPG has not yet published a revised cost figure for Unit 1. The utility’s most recent public baseline, a 2025 Release Quality Estimate, put the total cost of the four-unit DNNP — including interest during construction, cost escalation and contingency — at approximately C$20.9 billion. Within that figure, Unit 1 alone was estimated at roughly C$6.1 billion, with a further C$1.6 billion allocated to systems and services shared across all four units.

Those numbers were already treated as a live estimate rather than a fixed contract price: OPG’s regulatory filings describe the Unit 1 figure as a Class 3 estimate, a mid-range accuracy category typically used before a project’s engineering is fully defined. The comprehensive assessment now under way is expected to produce a more advanced estimate, along with a new schedule, once OPG and its contractors have worked through the specific risks identified during construction.

Why the Delay Matters Beyond Darlington

The outcome of OPG’s review carries weight well past the Darlington site. The BWRX-300 is also the reference design behind Synthos Green Energy’s planned six-unit project at Poland’s Pątnów site and the UK fleet that SGE and OPG’s Origin Nuclear venture are preparing to operate, among other prospective deployments that have pointed to Darlington as a proof point for cost and schedule on a “first-of-a-kind” SMR. A material cost or schedule revision at Darlington is likely to be scrutinised by developers and regulators weighing BWRX-300 projects elsewhere.

It also lands at a moment when Ontario’s own electricity planners have been citing rising demand — from electrification, data centres and industrial growth — as the rationale for adding new nuclear generation rather than relying solely on the refurbishment of existing CANDU units at Darlington and Bruce. A later in-service date for Unit 1 would push back when that incremental capacity becomes available to the grid, though OPG has given no indication that the project itself is at risk of cancellation.

Sources

• Ontario Power Generation, “OPG Reports 2026 Third Quarter Financial Results,” news release, November 2026 — for the disclosure that Unit 1 will not meet its October 2030 target and that a comprehensive cost and schedule assessment is under way.
• NucNet, “OPG Begins ‘Comprehensive Assessment’ As Canada SMR Project Faces Delays And Budget Overruns,” 12 November 2026 — for OPG’s characterisation of the BWRX-300 programme’s role in Ontario’s energy plan.
• World Nuclear News, “Canada’s first SMR project: How is CAD20.9 billion cost calculated?” — for the baseline cost breakdown of the four-unit Darlington New Nuclear Project.

Illustrative image. Photo: Nuclear Regulatory Commission, Public domain, via Wikimedia Commons — source