Leading small modular nuclear reactor will be late and over budget
Ontario Power Generation is building North America’s first SMR outside Toronto. The utility says it will miss the initial $7.7 billion budget and 2030 timeline.
North America’s first small modular reactor project is running into two familiar challenges for the nuclear industry: timing and cost.
Ontario Power Generation said in a Tuesday earnings release that the first BWRX-300 unit at its Darlington site will not come online by its October 2030 target and will blow past its budget of $7.7 billion Canadian ($5.4 billion U.S.). The utility didn’t share new targets — it’s working on a revised assessment of cost and schedule that it expects “to be substantially completed by mid-2027.” It is the project’s second slip: When Ontario Power announced the design in late 2021, it said the reactor could be completed as early as 2028.
The Darlington project, located east of Toronto, is the first new nuclear build in Canada in more than three decades. It’s also the first test of a small modular reactor design that is being pursued by developers in the U.S. and beyond. The Tennessee Valley Authority received a construction permit for a BWRX-300 from the Nuclear Regulatory Commission in September. Developer Blue Energy has also started the NRC application process to build a BWRX-300 in Texas.
Unlike other next-gen nuclear designs recently greenlit for construction in the U.S., GE Vernova Hitachi’s BWRX-300 uses the same light-water technology that undergirds most of the world’s existing nuclear fleet today. It’s designed to produce 300 megawatts of carbon-free electricity — a substantial amount, but far less than a conventional large-scale reactor.
Timeline and cost overruns have plagued North American nuclear projects and help explain why reactor construction has been anemic in recent decades. Just look at the latest nuclear power plants to be completed in the U.S.: Georgia Power’s Vogtle units 3 and 4, both large-scale AP-1000 reactors that came online in 2023 and 2024, took an extra seven years and $17 billion to wrap up.
Nevertheless, nuclear energy is seeing resurgent financial and policy support in North America and elsewhere as demand for electricity — especially carbon-free electricity — rises.
The Darlington project is part of that wave. In total, Ontario Power Generation plans to build four units at a cost of $20.9 billion Canadian, and federal and provincial investment funds have since committed up to $3 billion Canadian for minority stakes in the project. In the U.S., the Biden administration backed nuclear power as an anchor for an emissions-free grid, and both Trump administrations have embraced it under the banner of “energy dominance.”
Proponents of SMRs argue that smaller, repeatable designs like the BWRX will be cheaper and faster to build than large-scale reactors. The idea is that mass manufacturing and construction of these reactors will create a sort of learning-curve effect, so even if the first unit is expensive to make, the 100th unit will be far cheaper. But right now, this is only a hypothesis. Just two SMR plants are operating commercially worldwide, in Russia and China, and some in the nuclear industry argue that it’s more economical to stick with big reactors.
Given that the Darlington project is the first attempt at building a BWRX-300, some budget and timeline overruns aren’t surprising. Ontario Power Generation itself said that the update “reflects GE Vernova Hitachi (GEVH) Nuclear Energy’s ongoing engineering for its first-of-a-kind SMR, which has impacts on construction execution and supply chain performance.”
“GE Vernova Hitachi is committed to working closely with Ontario Power Generation (OPG) and our partners to deliver the Western world’s first commercial SMR,” a GE Vernova Hitachi spokesperson told Canary Media in an emailed statement. “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.”
While overruns are expected for a first-of-its-kind project, their scale matters. If costs or timelines balloon by too much, it could have a chilling effect on the other efforts to develop BWRX-300 reactors. Vogtle offers a cautionary precedent. Even though its second new reactor was 30% cheaper to build than its first, what’s remembered is the project’s enormous overall price tag.
Dan McCarthy is a senior editor at Canary Media.
