OPG says first Darlington SMR will miss 2030 date and C$7.7B estimate

The first BWRX-300 small modular reactor at Ontario Power Generation's Darlington New Nuclear Project will not reach commercial operation in October 2030 or be finished within its C$7.7 billion cost estimate, OPG said on November 10, 2026. The utility disclosed both in its third-quarter results and, the same day, told the Ontario Energy Board in an impact statement that strips the unit's forecast capital costs and output from its 2027–2031 rate application. There is no new date or number yet: OPG is running a comprehensive assessment of cost and schedule that it expects to substantially complete by mid-2027.

What OPG says went wrong

The C$7.7 billion covered Unit 1 "inclusive of required systems and services that would be common to all SMRs planned as part of the project," per OPG's release. The utility ties the slip to GE Vernova Hitachi Nuclear Energy's "ongoing engineering for its first-of-a-kind SMR, which has impacts on construction execution and supply chain performance," and says it is working with the vendor to complete the outstanding engineering scope. The assessment will weigh engineering design maturity and completion timelines, first-of-a-kind complexity, updated market conditions including inflationary and geopolitical risk, and how well mitigation and recovery actions work.

"We have identified risks that will impact Unit 1's schedule and budget," said Nicolle Butcher, OPG's president and CEO. The vendor reads the cause more broadly. GE Vernova Hitachi spokesperson Jonathan Allen told The Globe and Mail: "While engineering and design maturity are important considerations, as OPG's update recognizes, there are multiple interconnected contributions across engineering, procurement and construction, as well as evolving market conditions, including inflation and geopolitical risks."

Construction has not stopped; Butcher says "critical work continues every day on site." OPG's release lists the 2.1-million-pound basemat, assembly of the tunnel boring machine for the condenser cooling water tunnel, with tunnelling expected to start in the last quarter of 2026, and the first turbine building pour. The four-unit project carries a total budget of C$20.9 billion, the Globe reports.

The province had a week of good news first. Ontario spent November 6 and November 9 announcing Darlington supplier contracts (our roundup), and the delay and overrun landed on November 10. Minister of Energy and Mines Stephen Lecce's statement credits the project with C$362.7 million in contracts, per the Globe, and says: "Ontario has asked OPG to use this additional time to assess how it can boost domestic contracts and work to drive even more jobs and manufacturing to the country."

The rate case loses its reactor

Until November 10, Unit 1 was part of the power prices OPG and its project partnership had asked regulators to set for 2027 through 2031. OPG and that partnership, DNNP LP, which is executing the project, are before the Ontario Energy Board in case EB-2025-0297 to set those payment amounts, and the original evidence had Unit 1 entering commercial operation in October 2030. On October 23 the two told the board they needed time to assess "an evolving change" and would report no later than November 13. The answer, filed by their counsel, Charles Keizer of Torys, in a November 10 letter, is that Unit 1 is "no longer expected to achieve the forecast in-service date of October 2030, as specified in the pre-filed evidence." The impact statement adds that "an updated high confidence schedule determination for Unit 1 has not yet been concluded."

So DNNP LP has taken the reactor out of the five-year plan. Its forecast capital spending and in-service additions for 2027–2031 are removed, its proposed rate base is zero in every year, and its production forecast drops to zero, from 0.5 TWh in 2030 and 1.9 TWh in 2031. Its proposed revenue requirement over the period falls by about C$2.3 billion, from about C$2.7 billion to about C$0.4 billion. The filing now puts the typical residential customer's monthly bill increase at 1.9%, or C$2.69, a year on average over 2027–2031, down from 2.4%, or C$3.40, in the original application.

We read much of that relief as deferral rather than savings. Interest on the reactor's construction spending will still be recorded, on actual cumulative capital costs, in a variance account whose balance Ontario's regulation requires the board to let DNNP LP recover the following year, to the extent the board is satisfied the amounts are accurately recorded. If Unit 1 does enter service during 2027–2031, its actual capital-related revenue requirement goes into another account, subject to future board review. What leaves the rate case is the forecast, not the reactor's cost.

The filing also reopens a settlement. OPG and DNNP LP filed a settlement proposal on October 5, 2026, and have asked the board to return the parties to the settlement conference as soon as possible so they can propose an amendment. OPG's own nuclear revenue requirements and its hydroelectric proposals are unchanged, apart from a smaller payment-shaping deferral: OPG now proposes to push C$300 million of its 2027 nuclear revenue requirement into 2028, down from C$500 million.

What comes next

The licensing track runs separately. OPG applied in March 2026 for a 20-year licence to operate the unit, and the Canadian Nuclear Safety Commission's project page says the decision follows a public hearing that "will be announced at a later date." The commission has scheduled a webinar on the project's construction and operating licence application for December 4, 2026.

Other developers are lining up behind the same design. TVA holds a US construction permit for a BWRX-300 at Clinch River, and Studsvik has picked the reactor for a four-unit project in Sweden. Other BWRX-300s are planned in the US, the UK and Poland, among other countries, but Canada's would be the first, the Globe notes. OPG says it will provide further updates as additional material information becomes available.