Quick answer
Small modular reactors (SMRs) are smaller nuclear units designed to be built more quickly than large stations. Ontario Power Generation is building four BWRX-300 units at Darlington; the first is planned to be in service by the end of 2030, and the four would produce 1,200 MW.1
The Darlington project
- Each BWRX-300 unit is designed to generate about 300 MW.1
- The first unit is planned to be in service by the end of 2030.1
- Together, the four units would produce 1,200 MW, pending regulatory approvals.1
Why Ontario is adding nuclear
Ontario's grid operator forecasts demand growing 65% by 2050 and new supply needs from the early 2030s.2 Nuclear supplied 48.5% of Ontario's electricity in 2025.3
Other new nuclear
OPG is also exploring the Wesleyville site in Port Hope, which its early assessments say could host up to 10,000 MW of new generation.4
Common follow-up questions
How big is an SMR compared with a large reactor?
A BWRX-300 is designed for about 300 MW; Pickering's four remaining units together provide about 2,100 MW.
When will SMRs start producing power?
The first Darlington unit is planned to be in service by the end of 2030.
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