In January, Ontario Energy Minister Stephen Lecce told a room full of business and energy officials that communities across the province have been “petitioning us for a small modular reactor.”
The emerging nuclear technology is exactly what it sounds like: essentially a smaller nuclear reactor, often referred to as an SMR, that can produce enough electricity for up to 300,000 homes. And it’s all anyone in Ontario’s energy space can talk about. It’s poised to be a major facet of the province and country’s plan to become an “energy superpower.”
There’s a simple case for expanding Ontario’s already robust nuclear fleet. We desperately need more clean, reliable, around-the-clock electricity supply to satisfy our thirst for artificial intelligence, electric cars and all the things we’ll be plugging in over the coming decades.
The province is betting nuclear energy will satisfy the bulk of our power demand, and so is Canada. The two levels of government have promised billions of dollars toward the country’s (and North America’s) first small modular reactor power plant. The project is under construction at the Darlington Nuclear Generating Station in Bowmanville, Ont., just over an hour’s drive east of Toronto, and led by the Crown corporation Ontario Power Generation. The plan is to build four of these reactors at Darlington over the next decade.
The catch: we’ve never built a small modular reactor before.
Both Russia and China have operational small modular reactors, while Argentina has a pilot under construction. But Ontario would be first in the G7 to build one.
That doesn’t seem to have fazed the government — provincial or federal. Prime Minister Mark Carney has referred the Darlington New Nuclear project to his Major Projects Office for consideration to be fast-tracked. That means federal officials could support the financial and licensing needs of all four small modular reactors.
Here’s everything you need to know about Ontario’s pursuit of small modular reactors, or SMRs.
What are small modular reactors, or SMRs?
They’re like traditional nuclear reactors, but, well, smaller in both the amount of power they produce and their physical size. An SMR and its components can range from the size of a shipping container to a football field.
But they produce power in the same way, splitting radioactive uranium atoms into smaller elements. This process releases heat that is used to turn water into steam, which drives a turbine, producing electricity.
That similarity is one of the reasons Ontario Power Generation is confident in its plan to build a first-of-its-kind reactor at Darlington, with contractor GE Vernova Hitachi — the small modular reactor is a scaled-down version of an existing nuclear reactor model (the tenth generation of it, in fact), Subo Sinnathamby, Ontario Power Generation’s chief projects officer, told The Narwhal.
While the physics are largely the same, small modular reactors are easier to build than a traditional reactor. “They’re almost like Legos: pre-made bits that come out of the factory and are put together on site,” Kirk Atkinson, associate professor and associate industrial research chair in Ontario Tech University’s department of energy and nuclear engineering, said.
Atkinson, who is also director of the university’s Centre for Small Modular Reactors, says this kind of simplification allows small modular reactors to be produced at reduced costs and much more quickly than full-scale nuclear.
But while traditional nuclear reactors use uranium, a fuel Canada is the world’s second-largest producer and exporter of, small modular reactors require enriched uranium, which Atkinson likened to concentrated orange juice. Canada doesn’t have any of it in-house, and that’s a hurdle Ontario is trying to get over quickly. More on that below.
How much power does an SMR produce and for whom?
A single small modular reactor at Darlington will produce 300 megawatts of electricity, which is enough to power 300,000 homes.
The lower capacity and size means they make sense in places with smaller populations, everywhere from rural, remote Ontario to Saskatchewan, helping them move away from diesel generators. They can also be used to provide independent or backup power for industrial facilities, mines or data centres, assuming regulation permits this.
Unlike small modular reactors in remote communities or independent uses, Darlington’s reactors will be tied into Ontario’s power grid.
What is Ontario Power Generation?
The provincial Crown corporation, often known as OPG, has built and currently operates a significant portion of the nuclear generators in the province.
Atkinson said it is “the only entity in Canada that is large enough and wealthy enough and skilled enough to take a project like a small modular reactor and be the proving ground of a nation, be a proving ground of the western world.”
For more than a decade, Ontario Power Generation has had an empty site near its Darlington nuclear facility licensed for new nuclear builds. That site is now being used to build the first of four small modular reactors, technically known as the GE Hitachi Boiling Water Reactor X-300 (or the BWRX-300). The full-scale nuclear version of this reactor is in use in the United States.
“We had a leg up on other nations because we already had a site suitable for this,” Atkinson said. “[Ontario Power Generation] was ahead of the times.”
How much will it cost Ontario taxpayers to build the first SMR?
Absolute bucketloads.
Initial forecasts suggest the first small modular reactor may cost $6.1 billion, plus another $1.6 billion for systems around it that will service all four once complete.
In total, Ontario Power Generation anticipates the four reactors at Darlington to cost $20.9 billion.
The federal government’s arm’s-length investment vehicle, the Canada Growth Fund, has given the first leg of the project $2 billion, while the province is putting forward $1 billion through its Building Ontario Fund.
Both governments say these investments will be worth it because Ontario’s small modular reactors will create 18,000 jobs during construction and 3,700 jobs during operation. They also predict the project will contribute $38.5 billion to Canada’s gross domestic product through its construction and continued operation over 65 years.
While it looks like the cost of the Darlington project will be borne by taxpayers, the province has noted it is “exploring potential financial instruments that would benefit ratepayers, and in parallel, [Ontario Power Generation] continues to explore other optimal financing arrangements.”
For now, the Crown corporation has asked the Ontario Energy Board to consider permitting it to nearly double the cost of nuclear power for ratepayers to help recoup the very high costs of building the small modular reactors. This follows a rule change made by the Doug Ford government allowing electricity rate increases for generating infrastructure that hasn’t been built yet. We’ll have to wait and see what the independent regulator decides.
When will the first SMR be operational?
If all goes well, 2030.
“We have a licence to construct. We don’t have a licence to operate, yet,” Sinnathamby, of Ontario Power Generation, said.
The power to grant that is in the hands of the Canadian Nuclear Safety Commission, w
hich will greenlight the technology once it’s built, only if it meets all environmental and safety standards.
It also depends on whether we manage to secure enough enriched uranium to operate them.
So where is Ontario going to get the enriched uranium needed for small modular reactors?
Maybe the U.S. Maybe France.
In its 2024 fall economic statement, the federal government, led by then-prime minister Justin Trudeau, said it intended to backstop up to $500 million in enriched nuclear fuel purchase contracts from allied countries to support small modular reactor operators.
Sinnathamby said Ontario Power Generation has “a very diverse partnership to ensure we have a strong supply of enriched fuel.” Canada has an abundance of uranium, while the United States has facilities to produce the refined form. Sinnathamby noted the American company producing that enriched uranium is a subsidiary of GE Vernova Hitachi, which is building the SMR technology, and so is very invested in the project’s success and that supply chain.
Nevertheless, in light of the U.S. trade tensions, Sinnathamby said Ontario Power Generation has also signed a deal with French company Orano to garner enriched uranium.
“We’re quite comfortable and confident around fuel security and supply,” Sinnathamby said.
Who wants Ontario’s SMRs?
If you ask Lecce … everyone?
In 2022, the governments of Ontario, Saskatchewan, New Brunswick and Alberta agreed to a joint strategic plan to collectively build and deploy small modular reactors. Ontario and Nova Scotia have made a similar agreement. Some of these provinces are “starting from scratch,” George Christidis, president and CEO of the Canadian Nuclear Association, said, which is what makes Ontario’s experience and expertise important.
In the past year, Lecce has been on a whirlwind of international trips to secure deals both to deploy small modular reactors and support them, everywhere from New York to Poland.
Ontario Power Generation has also been inundated with requests to visit Darlington to see the SMR site, Sinnathamby said, adding, “I joke that one of my execs is on full-time tour duty because of the number of visitors we have.” That has included representatives from European countries, as well as U.S. government agencies.
How does Lake Ontario, and water in general, factor into the SMRs at Darlington?
The three major nuclear sites in Ontario are all close to Great Lakes, which Atkinson said act as “very large bathtubs of water” that can be used to cool the reactors.
To that end, Sinnathamby said the small modular reactor site in Darlington will include a tunnel into Lake Ontario to bring in water for cooling, “so that wouldn’t be different from any other technology, per se.”
What will differ is the volume of water needed; that depends on the eventual size of the reactor, the number of components and how many are built.
What will we do with the waste produced by small modular reactors in Ontario?
We’re not sure, but everyone is confident there will be a plan when they’re operational.
“Nuclear waste is very securely managed and regulated in Canada,” Christidis said. “There’s a strong and proven safety standard in this industry.”
This question ultimately depends on the Nuclear Waste Management Organization, a non-profit established by Ontario Power Generation, New Brunswick Power Corporation and Hydro-Québec and empowered by the federal government to create a plan for nuclear waste management.
The organization has long been tasked with finding a site for nuclear waste produced by traditional reactors, and last year chose Ignace, Ont., as the site for a repository.
But waste produced by small modular reactors isn’t included in the plan for Ignace, and they may produce higher amounts of nuclear waste per unit of energy than traditional reactors.
Sinnathamby, who sits on the board of the waste management organization, expects robust consultation on what to do with small modular reactor waste before it is operational. “It could potentially go to Ignace,” she said, but either way, the organization is mandated to find a solution for the waste.
How do SMRs fit into Ontario’s other nuclear plans?
Ontario is currently in the midst of either refurbishing or expanding all three of its major nuclear plants, which collectively provide more than 50 per cent of the province’s electricity.
The government has also directed Ontario Power Generation to explore the possibility of building a new nuclear facility in Port Hope, Ont. If built, it would be the second nuclear facility built since 1993 — only after Darlington’s small modular reactors.
If Ontario has never built an SMR before, will it actually be built?
Many in politics and the industry vigorously believe so.
But as with all new technology emerging in the energy transition — from carbon capture to hydrogen — a lot remains to be seen.
“We’re kind of at the beginning stage of this journey,” Atkinson said. “It’s only once we’ve built some and we’ve had the chance to stand back and look at it will we be able to provide better answers.”
Christidis is resolute. “It isn’t just hype. It’s actually very real,” he said. “That’s in the sense of real projects, real jobs, real investments. It’s a success story in the making, here and internationally.”
This story is part of a series called Shockwave: Rising energy demand and the future of the Great Lakes. The Great Lakes region is in the midst of a seismic energy shakeup, from skyrocketing data centre demand and a nuclear energy boom, to expanding renewables and electrification. In 2026, the Great Lakes News Collaborative will explore how shifting supply and demand affect the region and its waters.
