On May 8, the Province of Ontario, Canada, gave the green light for Ontario Power Generation to begin construction on the first of four small modular reactor units at its Darlington New Nuclear Project site. This represents the first new nuclear build in Ontario in more than three decades.
Once in service by the end of 2030, the first BWRX-300 SMR unit will be capable of generating 300 megawatts.
In total, OPG’s SMR fleet will be capable of producing 1,200 MW of electricity to help support Ontario’s electrification, while serving as a growth platform for Canada’s nuclear supply chain, OPG said.
To ensure a successful buildout, OPG will be leveraging more than 7,000 lessons learned from its Darlington Refurbishment project, which remains on track to be completed by 2026. The company will also incorporate lessons learned from the construction of the first SMR to the rest of the fleet.
The Province’s approval to proceed comes after OPG received a Licence to Construct the first SMR unit in April from the Canadian Nuclear Safety Commission.
On the ground, the project team has been busy preparing for this moment, including advancing site preparation work and procuring long-lead components.
Since Fall 2022, dozens of trucks have been relocating clean soil across the site to level out the lands intended for the future SMR units. Crews have also been installing various utilities, including fire lines, water lines, sanitary sewer lines, and network cabling. Construction on a few important buildings, including the on-site fabrication building, is also progressing well.
Meanwhile, the team continues to excavate for the Reactor Building shaft—a critical milestone—in preparation for construction of the reactor building.
To support a fleet of SMRs, the DNNP team has worked to secure several long-lead items, including the reactor pressure vessel. As the SMR’s largest component, the vessel will contain the reactor core, coolant, and support structures.
Meanwhile, the generator rotor—a key component of the turbine-generator system that converts heat from the reactor into electrical power—has been forged and is now undergoing pre-machining. It’s expected to arrive at the project site by summer 2027.
Finally, later this summer, the project’s tunnel boring machine will arrive from Germany at the new nuclear site for storage until assembly in early 2026. Once operational, the massive machine will be used to drill the condenser cooling water tunnel, which will measure 3.4 kilometers long and 6.05 meters in diameter.
