AtkinsRéalis Selected to Support Major Substation Expansion for Darlington SMR Integration
AtkinsRéalis Group Inc. (TSX: ATRL), a global engineering and nuclear services leader, has been awarded a significant multi-year Owner’s Engineer mandate by Hydro One Networks Inc. (Hydro One) for the expansion of the Bowmanville Switching Station in Ontario. The expansion, located directly across from Ontario Power Generation’s (OPG) Darlington Nuclear Generating Station, is a critical component in enabling the grid connection of four planned Small Modular Reactors (SMRs) at the Darlington New Nuclear Project site.
Hydro One, headquartered in Ontario and employing nearly 10,000 people, is responsible for the province’s electricity transmission and distribution infrastructure. This collaboration underscores Hydro One’s central role in building the next generation of clean energy capacity to support Ontario’s growing population and increased electrification initiatives.
Strengthening Ontario’s Electricity Infrastructure
The Bowmanville Switching Station expansion is designed to accommodate the significant new power output expected from OPG’s forthcoming fleet of SMRs. These reactors represent one of Canada’s most prominent clean energy developments and are part of a broader national strategy to address increasing electricity demand while progressing toward climate goals.
SMRs at the Darlington site will be among the first grid-scale deployments of the technology in Canada. The new capacity is expected to play a critical role in decarbonizing Ontario’s energy mix and ensuring reliable, steady baseload power supply for decades.
Ian L. Edwards, President and CEO of AtkinsRéalis, emphasized the company’s longstanding involvement in major global energy infrastructure projects. “Delivering nation-building energy projects in Canada and around the world has been a hallmark of our work in the Power & Renewables sector for decades,” he stated. “This substation project is a vital connection between the Darlington New Nuclear Project and electricity consumers across southern Ontario, including the Greater Toronto Area.”
Supporting Growing Regional Power Demand
Southern Ontario is experiencing continual growth in population and industrial activity, which has driven demand for additional electricity resources. Key electrification projects—particularly transit modernization initiatives such as GO Transit electrification and the new Ontario Line—are expected to add approximately 100 megawatts of new demand to Toronto’s power requirements. These projects are aligned with provincial goals to reduce emissions from transportation and improve urban mobility.
As demand escalates, additional transmission and distribution infrastructure is required to ensure system stability and avoid bottlenecks. The expansion of the Bowmanville Switching Station will play a pivotal role in alleviating current congestion along regional transmission corridors, improving power flow efficiency, and enabling the integration of new clean energy generation.
Scope of Work and Technical Enhancements
AtkinsRéalis’ Power & Renewables specialists will deliver a range of engineering and project and program management services to support the expansion. Central to the project is the construction of a new 500 kV switchyard adjacent to the existing station. This addition is anticipated to double the site’s capacity and expand its footprint by roughly 30 to 40 acres.
Beyond the switchyard, the project will include the installation of new breakers, disconnect switches, and associated electrical equipment required to safely and reliably manage high-voltage power transmission. A new multi-purpose operations building will also be developed to house control systems, telecommunications infrastructure, protection equipment, and auxiliary support systems. New line entrance structures will facilitate the interconnection of high-voltage transmission lines, enabling efficient evacuation of power generated by the SMRs into the broader Hydro One grid.
The expansion is scheduled for completion before all four SMRs are brought online, ensuring the surrounding grid infrastructure is capable of receiving and distributing the additional power as soon as it becomes available.
Continuing a Legacy of Power Infrastructure Delivery
Stéphanie Vaillancourt, President, Canada, AtkinsRéalis, highlighted the strategic significance of this project within the province’s broader energy goals. “Transmission and distribution infrastructure is one of the backbones of Ontario’s significant electricity build-out program and requires sustained expansion,” she said. “This mandate reflects our differentiated end-to-end capabilities and continues to strengthen our long-standing relationship with Hydro One.”
AtkinsRéalis has a wide-ranging portfolio of major power and renewable energy work underway in Canada. Current notable initiatives include:
- Serving as Owner’s Engineer for the Champlain Hudson Power Express Project, a 545-kilometer buried transmission line capable of delivering 1,250 MW of clean hydroelectric power from Quebec to New York City.
- Providing engineering and design support for TES Canada’s Projet Mauricie, one of the largest green hydrogen facilities in Canada, expected to produce up to 70,000 tonnes of clean hydrogen annually.
- Project and construction management for the refurbishment of Rio Tinto’s Isle-Maligne hydropower plant in Alma, Quebec, helping to modernize and extend the life of critical renewable generation assets.
Internationally, the company is also involved in major transmission work such as the Saudi-Egypt Interconnection Project—a first-of-its-kind 3,000 MW, 1,300 km transmission line that will support power sharing across regions and benefit over 20 million people.
The Bowmanville Switching Station expansion is a strategically important infrastructure project that supports the integration of new nuclear generation capacity into Ontario’s power system. AtkinsRéalis’ role as Owner’s Engineer reflects both its deep expertise in power system engineering and its longstanding commitment to delivering essential clean energy infrastructure. The project will help strengthen grid reliability, support electrification, and contribute to building a more resilient and sustainable energy future for Ontario.
