Darlington SMR Unit 1 to Miss October 2030 Date and C$7.7B Budget

Ontario Power Generation (OPG) said on Nov. 10, 2026 that the first Darlington SMR (small modular reactor) unit will not reach commercial operation by its October 2030 target or be built within its C$7.7 billion estimate, with a full cost and schedule reassessment due by mid-2027.

OPG gave the news in its third-quarter results release. It said Unit 1 of the Darlington New Nuclear Project (DNNP), a 300 MWe BWRX-300 from GE Vernova Hitachi Nuclear Energy, is "no longer expected" to meet the October 2030 commercial operation date or the budget, which includes the systems and services common to all planned SMRs. OPG attributed this to the vendor's ongoing engineering of a first-of-a-kind design, which it said affects construction execution and supply chain performance. The Globe and Mail, which first reported the story, adds that OPG's lawyer told the Ontario Energy Board in a letter the same day that the unit is no longer expected to meet the forecast in-service date. Neither source gives a new date or a revised cost.

This changes what Voltgrid reported on Nov. 10. Our earlier story on the Darlington project set out an OPG target of grid connection by the end of 2030; that target now has no replacement date. OPG's chief executive, Nicolle Butcher, said in the release that the company has "identified risks that will impact Unit 1's schedule and budget" and is working to fully assess them.

Why Darlington SMR Timing Matters for Firm Power Buyers

OPG describes Darlington as the G7's first small modular reactor, so its schedule is an early real-world test of how long and how much a BWRX-300 takes to build. For a data-center operator, a firm-power plan that depends on a 2030 SMR start now carries a schedule risk that OPG itself has not yet sized.

What OPG and GE Vernova Hitachi Said

OPG said the assessment will weigh the completion of engineering, the maturity of the design, the complexity of a first-of-a-kind build, updated market conditions including inflation and geopolitical risk, and the effect of mitigation actions. It said it intends to give further updates as material information becomes available.

GE Vernova Hitachi spokesperson Jonathan Allen told the Globe and Mail that "engineering and design maturity are important considerations" but pointed to "multiple interconnected contributions across engineering, procurement and construction," plus inflation and geopolitical risk. The two companies therefore differ in emphasis on where the problem lies.

Ontario Energy Minister Stephen Lecce said in a statement, as quoted by the Globe, that the province expects GE Vernova Hitachi and the project partners to meet their commitments, and that Ontario asked OPG to use the extra time to see how it can raise domestic contracts. The same report puts contracts to date at C$362.7 million.

OPG said the project completed assembly of the tunnel boring machine in the third quarter, with tunnelling on the condenser cooling water tunnel expected to begin in the last quarter of 2026, and finished the first turbine building pour. It also cited the 2.1-million-pound basemat, which it calls the first nuclear foundation laid in Canada in more than 30 years. The Globe reports that the reactor pressure vessel is being assembled at a BWX Technologies plant in Cambridge, Ont.

What Is Still Unconfirmed on Cost and Date

No revised in-service date and no revised cost have been published. The C$7.7 billion figure covers Unit 1 plus common systems; the C$20.9 billion budget is for all four units, and OPG has not said whether it changes. OPG expects the assessment to be substantially complete by mid-2027. The Ontario Energy Board letter is known only through the Globe report; Voltgrid has not read the letter itself.