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The province takes advantage of a trained workforce from a C$12.8 billion nuclear reform, over 100 local suppliers, and existing infrastructure in Darlington to reduce risks associated with a technology that Canada intends to replicate in other regions.
Ontario has begun construction on one of the West’s most ambitious nuclear ventures: four small modular BWRX-300 reactors, each with a capacity of about 300 MW, at the Darlington complex in Canada. The first unit is slated to physically advance in 2025 and is expected to start operations in 2030, with the estimated total cost for the complete set reaching C$20.9 billion, according to a report by Reuters published on August 27, 2026.
The project aims to do more than just add new generation capacity.
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The province wants to leverage an active supply chain, experienced workers, and existing nuclear infrastructure to mitigate time and cost risks.
Additionally, Canada plans to significantly expand electricity generation in the coming decades.
Thus, Darlington serves as a sort of commercial-scale test for a technology that other provinces are closely monitoring.
First BWRX-300 Under Construction in Darlington
Ontario Power Generation (OPG) started construction in May 2025 on the first of the four units planned for the Darlington New Nuclear Project.
The selected reactor is the BWRX-300, developed by GE Hitachi Nuclear Energy.
Each unit will have a capacity of approximately 300 MW.
Therefore, when all four are operational, the complex should contribute about 1,200 MW of new nuclear capacity.
OPG states that this power will be sufficient to supply electricity equivalent to the consumption of approximately 1.2 million homes.
Thus, the project is not merely an experimental facility.
It is designed to operate directly within the electrical grid.
First Unit Expected to Begin Operations by the End of 2030
The timeline places the first unit in service by the end of 2030.
If achieved, the reactor could become one of the first commercial large-scale SMRs to generate electricity in the Western world.
However, the date still depends on project execution, licensing, and commissioning.
Therefore, 2030 represents the current estimate, not a guaranteed date.
The next three units are expected to progress thereafter.
OPG aims to have them operational by the mid-2030s, subject to necessary approvals.
Four Reactors Will Cost Approximately C$20.9 Billion
Cost is one of the most closely monitored aspects of the project.
OPG estimates the total budget for the four units at C$20.9 billion.
The first unit is expected to carry the largest share of risk.
According to the operator, the first SMR has an estimated cost of C$6.1 billion, while systems and services shared among the four units add approximately C$1.6 billion.
Thus, the budget associated with the first phase reaches C$7.7 billion.
Subsequently, the company expects to reduce costs for the following units.
This strategy relies on repeating the same design multiple times.
The more the supply chain learns, the less need there tends to be for alterations, rework, and additional mobilization.
First Unit Concentrates the Largest Risk of the Program
This strategy also creates a vulnerability.
Analyst Zoé Sumont from Wood Mackenzie warned Reuters that the first unit concentrates the risk of a pioneering project.
Moreover, the program’s economy relies on a decrease in costs for subsequent units.
According to her, no SMR has yet fully demonstrated this reduction in a comparable commercial sequence.
Therefore, the program bets on the so-called repetition effect.
The first unit costs more.
Then, the team repeats the same design.
As a result, engineers and suppliers learn where to save time and reduce expenses.
However, if the first project suffers significant delays or design changes, part of that advantage may disappear.
Ontario uses C$12.8 billion refurbishment as training for SMRs
The province believes it is better prepared than other markets because it has just completed a massive nuclear refurbishment.
For nearly a decade, OPG modernized the four existing CANDU reactors in Darlington.
The project had a budget of C$12.8 billion.
Additionally, it extended the operational life of the facility by approximately 30 years.
The work was completed in the first quarter of 2026.
And there is one particularly important detail: the refurbishment finished four months ahead of the original schedule and about C$150 million under budget.
This track record now serves as a case for the new program.
Refurbishment workers retained to build new reactors
Large nuclear projects rely on specialized professionals.
During the Darlington refurbishment, Ontario maintained a trained workforce for years in complex nuclear activities.
Now, some of these workers are moving to the new project.
According to information provided by OPG to Reuters, many professionals who worked on modernizing the CANDU units remained available for the BWRX-300.
This reduces the need to form an entirely new team.
Moreover, the workers already understand the safety procedures, documentation, and quality requirements mandated by the nuclear sector.
Thus, the previous refurbishment acts as a sort of industrial school for the next generation of reactors.
More than 100 Ontario companies to supply components and services
The local supply chain has also scaled up.
Reuters reports that over 100 companies from Ontario are expected to provide equipment and services for the project.
OPG also states that a large portion of spending will remain within Canada.
In earlier planning disclosed, more than 80% of the contracts for the Darlington New Nuclear Project were to be acquired domestically, while additional parts would come from Europe and Japan.
Thus, the nuclear program is no longer merely an equipment purchase.
It generates demand for manufacturers, engineering firms, construction, maintenance, and specialized services.
This logic also appears in other large energy infrastructure projects. The recent construction of Baltica 2 required 111 foundations of up to 100 meters and about 1,900 tons, illustrating how generation projects depend on an entire industrial chain before producing the first megawatt.
Reactor Receives Pressure Vessel Manufactured in Ontario
Production has already begun within the province.
The BWXT produces the reactor’s pressure vessel at its manufacturing facility in Ontario.
This component ranks among the most critical parts of the nuclear plant.
It houses essential reactor equipment and must meet stringent safety and quality standards.
Additionally, in April 2026, workers installed a massive structural base at the site.
The piece weighed approximately 2.1 million pounds, or about 950 tons.
The scale of this component indicates that the term “small modular reactor” can be visually misleading.
Small, in this case, means smaller in comparison to large conventional reactors.
The infrastructure remains industrial and heavyweight.
Modular Base of Nearly 950 Tons Installed All at Once
OPG emphasizes that the foundation of the reactor building featured an innovation.
The team fabricated and assembled a large modular structure made of steel and concrete before lowering it entirely to the final location.
This marks the first time in Canada that such a foundation for a reactor building underwent modular assembly in this manner.
Thus, the project aims to extend the concept of modularity beyond nuclear equipment.
Rather than slowly constructing each element on-site, teams produce larger parts in a standardized way.
They then transport and install these modules.
If this strategy proves successful, it could shorten timelines for future units.
Building Within an Existing Nuclear Complex Reduces Risks
Darlington offers another significant advantage: much of the infrastructure already exists.
The site has roads.
In addition, it comes with port facilities, electrical connections, security systems, and access to water for cooling.
There is also a community accustomed to nuclear operations.
According to experts consulted by Reuters, utilizing an active nuclear site can reduce several years from the deployment schedule compared to building in a completely new area.
Thus, the choice of Darlington is not only about proximity to Toronto.
It reduces the amount of infrastructure that needs to be developed from scratch.
Electric Grid is Already Prepared for Nuclear Power Generation
Another benefit lies in the connection to the electrical system.
A new plant needs to deliver hundreds of megawatts.
This requires lines, substations, and integration with the grid.
Since Darlington already produces nuclear energy, much of this infrastructure is available.
Thus, the new SMRs leverage a site that already possesses high-capacity connections.
This advantage reduces some external construction work.
Moreover, it avoids the need to develop an entirely independent transmission corridor.
The need to reinforce networks accompanies nearly all forms of generation. In another context, PowerChina has expanded its strategy in renewables and transmission after 20 years in Brazil, illustrating how generating electricity and transporting it remain inseparable parts of the same challenge.
Repeating Four Identical Units is the Bet to Lower Costs
Ontario’s plan relies heavily on standardization.
GE Vernova Hitachi aims to apply the lessons learned from Unit 1 in the construction of the next three units.
According to the company, the repetition of identical units with a common reference design is one of the keys to reducing costs.
This is because unique designs require repeated adaptations.
In contrast, a standardized model allows for the reuse of engineering, training, tools, and procedures.
Additionally, suppliers can manufacture similar components multiple times.
Thus, the logic resembles an industrial production line.
The challenge lies in applying this repetition to a highly regulated nuclear infrastructure.
OPG has already applied for an operating license for the first unit
Construction is progressing alongside the licensing process.
In March 2026, OPG requested the operating license for the first unit.
The process has entered public consultation.
Meanwhile, the company plans to request construction licenses for the three additional units.
This sequence illustrates how a nuclear project advances on multiple fronts simultaneously.
Engineers are working on-site.
Manufacturers are producing components.
At the same time, regulatory teams are reviewing documentation and safety.
Therefore, simply physically completing the structure is not enough.
The reactor can only generate commercially after receiving all necessary approvals.
Canada has 19 commercial reactors in operation
Ontario is building upon an already established nuclear base.
Canada has 19 commercial reactors, according to Reuters.
Of these, 18 are located in Ontario and only one operates in New Brunswick.
Together, they represent approximately 13.6 GW of installed capacity.
The province therefore concentrates virtually the entire Canadian nuclear industry.
This experience provides an advantage for new constructions.
There are operators.
There are suppliers.
In addition, universities and technical programs are already training professionals for the sector.
For this reason, Reuters describes Ontario as the spearhead of the Canadian nuclear renaissance.
OPG controls 5.4 GW of nuclear generation
Ontario Power Generation is among the largest players in this system.
The company has approximately 5.4 GW of nuclear generation.
It operates Darlington and Pickering.
Moreover, it owns the Bruce complex, although Bruce Power operates the site through a lease.
This experience reduces the gap between constructing and operating the new SMRs.
The same company executing the project has decades of knowledge about nuclear generation.
Thus, Darlington acts as an extension of an existing operation, rather than as the entry of a completely new company into the sector.
Canadian government aims to double electrical capacity by 2050
The project gains even more relevance when viewed within the national strategy.
In June 2026, the Canadian government announced a National Electricity Strategy with the goal of doubly increasing electricity generation capacity by 2050.
Much of this increase is expected to come from sources considered clean.
Currently, about 80% of Canada’s power generation comes from these sources, according to Reuters.
However, the electrification of transportation, industry, heating, and new data centers is expected to increase demand.
Therefore, maintaining the existing power generation capacity will not be sufficient.
The government needs to add capacity.
Canada aims for 10 new large reactors by 2040
The strategy also goes beyond SMRs.
The government has set a goal to have 10 new large nuclear reactors planned, under construction, or completed by 2040.
Additionally, at least one new project outside of Ontario should be under construction by 2035.
This goal aims to expand the nuclear industry to other provinces.
Today, the concentration in Ontario represents both an industrial advantage and a geographical limitation.
If Saskatchewan, Alberta, or other regions advance, the supply chain could gain national scale.
Saskatchewan and Alberta evaluate new nuclear projects
Reuters reports that new projects are under discussion in Saskatchewan and Alberta.
Moreover, northern territories are even exploring microreactors for remote communities.
Each region has different needs.
Saskatchewan has a smaller electrical system.
Alberta has strong industrial demand.
Meanwhile, Yukon, Nunavut, and the Northwest Territories face immense distances and isolated communities.
Thus, nuclear technology can take on different formats.
Large reactors can serve provincial systems.
SMRs can integrate into smaller grids.
Microreactors, in turn, emerge as a possibility for remote locations.
Wesleyville could host a 10 GW nuclear complex
OPG is already studying an even larger project.
The company has initiated the federal impact assessment process to develop up to 10 GW of nuclear capacity in Wesleyville, near Darlington.
The site has a historical curiosity.
There, an oil plant began construction in the 1970s but never fully operated as originally planned.
Now, the area may gain a new energy function.
OPG expects to apply for a construction license in the early 2030s.
The first reactors could begin operations in the mid-2040s.
Therefore, the project is still in a much earlier stage than the SMRs in Darlington.
Ontario bets on nuclear energy to meet industry and electrification demands
The province anticipates a significant increase in electricity demand.
Electric vehicles require more energy.
Additionally, new factories and industrial processes may shift from fossil fuels to electricity.
Data centers also increase consumption.
Therefore, Ontario seeks sources capable of providing large volumes of energy over extended periods.
Nuclear energy offers firm, low-carbon generation during operation.
However, new plants require high initial investments and long regulatory processes.
This trade-off between construction cost and continuous generation is central to the strategy.
While some regions are betting on renewables paired with batteries — such as the African plant that combines 233 MWp of solar with 526 MWh of storage to provide continuous power to a large copper complex — Ontario is looking to combine its renewable system with a long-term nuclear expansion.
Four SMRs can support about 1.2 million homes
The final capacity helps to understand the scale.
Four units of 300 MW represent approximately 1,200 MW.
According to OPG, the system will produce electricity equivalent to the consumption of about 1.2 million homes.
The first unit alone corresponds to approximately 300,000 homes, based on the company’s same reference.
These equivalencies serve only to dimension the production.
This does not mean the reactors will exclusively supply a fixed group of homes.
The power will enter the provincial grid.
Then, the system will distribute electricity among residential, commercial, and industrial consumers.
Program could generate tens of billions in economic activity
OPG also presents economic projections.
According to a study cited by the company, the construction and operation of the four units could add approximately C$ 38.5 billion to Canada’s GDP over 65 years.
Additionally, the project could sustain an average of about 3,700 annual jobs during that period.
During the construction phase, the impact would be much larger.
The cited estimate reaches 18,000 jobs per year over five years, considering both direct and indirect effects.
However, these numbers are economic projections, not permanent positions already created.
Therefore, they need to be treated as estimates.
Minister projects C$ 800 billion with set of nuclear projects
Reuters also cites a much larger projection from the provincial government.
Ontario’s Minister of Energy and Mines, Stephen Lecce, stated that the planned nuclear projects could add C$ 800 billion to the Canadian economy over their lifetime.
This amount does not correspond to the budget of the four SMRs.
It also does not represent revenue already generated.
It is an estimate of the economic impact of the planned set of nuclear investments.
The distinction is crucial.
The budget for the four SMR project remains approximately C$ 20.9 billion.
Darlington refurbishment became a key argument for the new bet
The previous project explains much of the province’s confidence.
The refurbishment of the four CANDUs required millions of work hours.
Additionally, teams replaced approximately 1,920 fuel channels, according to OPG data.
Even with the pandemic midway through the execution, the company completed the program below the original budget.
Thus, the government uses this performance as proof that the local supply chain can execute large nuclear projects.
However, refurbishing existing reactors and building a completely new model are different challenges.
Thus, the first BWRX-300 unit will continue to function as a crucial test.
New reactor still needs to prove cost at commercial scale
This is the central point of economic caution.
The BWRX-300 promises standardization.
Moreover, it uses a smaller, simplified design compared to large conventional reactors.
However, the market still needs to verify the actual cost of building an entire fleet.
If the first unit consumes significantly more capital than expected, the economics of subsequent units may change.
Similarly, delays could increase financial costs.
Therefore, analysts are closely monitoring each step at Darlington.
The project not only needs to function technically.
It must also demonstrate that repetition can reduce cost and time.
Ontario seeks to turn a pioneering project into a nuclear production line
The strategy can be summarized in a sequence.
First, Ontario refurbished four large CANDU reactors for C$ 12.8 billion.
In this process, it kept workers and suppliers active.
Then, it began construction of the first 300 MW BWRX-300.
Now, it plans to replicate the same design three more times.
If everything proceeds as planned, the total will reach 1.2 GW and cost approximately C$ 20.9 billion.
The first unit is expected to begin generating electricity in 2030.
In the meantime, Canada is preparing a much larger strategy, aimed at doubling electrical capacity by 2050 and planning, constructing, or operating 10 new large reactors by 2040.
Thus, Darlington has ceased to be just another generation project.
It has become a kind of industrial laboratory.
If the first unit meets costs and timelines, Ontario could demonstrate that a mature nuclear supply chain, a pre-licensed site, and the repetition of identical modules can transform small reactors into an almost mass-produced infrastructure.
However, if delays and budget overruns occur, the experience will also show why constructing the first example of a new technology remains the riskiest step.
Do you believe that 300 MW small modular reactors can make nuclear construction more predictable and affordable, or does the cost of C$ 20.9 billion for four units still place the technology far from mass production?
