Canada licenses construction of its first BWRX-300 small reactor at Darlington

April 2025 — The Canadian Nuclear Safety Commission issued Ontario Power Generation a licence to construct one GE Hitachi BWRX-300 reactor at its Darlington New Nuclear Project site in Clarington, Ontario. Here's what happened, what it cost, and what went wrong.

Cost and outcome (as of March 30, 2026)

Outcome: a power reactor construction licence for one BWRX-300, valid until March 31, 2035. (CNSC release)
Conditions: 4 facility-specific licence conditions and 3 regulatory hold points. (CNSC release; CNSC project page)
Progress: the first hold point, for the reactor building foundation, was removed March 30, 2026. (CNSC project page)
Cost: not stated by the CNSC.
Status: licensed to build, not to operate. OPG applied for an operating licence in March 2026. (CNSC project page)

What the regulator decided

The Commission concluded that OPG "is qualified to construct the reactor and will do so in a way that protects the health and safety of people and the environment." It weighed submissions from a two-part public hearing, held virtually on Oct. 2, 2024 and in person in Ajax, Ontario, on Jan. 8 to 10, 13 and 14, 2025. (CNSC release)

It also concluded it had met its constitutional duty to consult and, where appropriate, accommodate Indigenous rights. The site lies within the traditional lands and waters of the Michi Saagiig Anishinaabeg, the CNSC notes. (CNSC release; CNSC project page)

The decision doesn't allow the reactor to run. Operation would need a future licensing hearing and decision, World Nuclear News reported the regulator as saying. (World Nuclear News)

The reactor and the site

OPG picked the GE Vernova Hitachi BWRX-300 for Darlington in December 2021 and applied for a construction licence in October 2022. The project allows for up to four reactors; this licence covers one. (CNSC project page)

The road was long. OPG applied for a site preparation licence in September 2006, and the environmental assessment that began in 2007 was completed in 2012 with a finding that the project wasn't likely to cause significant adverse environmental effects, World Nuclear News reported. (World Nuclear News)

Earlier in 2025, GE Hitachi said early site preparation was done and that it expected "commercial operations expected to commence by the end of 2029," according to World Nuclear News. That's the vendor's target. (World Nuclear News)

How the hold points work

OPG's commitments for each hold point must be completed and verified by CNSC staff before the Commission, or someone it authorizes, will lift the hold and let construction continue. (CNSC project page)

Update: March 2026

The CNSC verified that OPG met the commitments for the first hold point, covering installation of the reactor building foundation, and removed it on March 30, 2026. On March 25, 2026, OPG applied for a 20-year licence to operate the reactor and an associated low- and intermediate-level waste storage structure. A public hearing on that application will be announced later. (CNSC project page)

The political pitch

Ontario Energy and Mines Minister Stephen Lecce said the project "could create up to 17,000 Canadian jobs during construction" and contribute over C$15 billion to Canada's GDP. Those are government projections, not results. (World Nuclear News)

What went wrong

It took nearly two decades. From the 2006 site licence application to a 2025 construction licence. (World Nuclear News)
Not licensed to operate. Operation needs a separate licence, which OPG only applied for in March 2026. (CNSC project page)
Two hold points remain. Construction can only pass each one after CNSC verification. (CNSC project page)
What we don't know yet: the reactor's cost and who pays for it. The CNSC pages we read don't say.

Our follow-up question for Ontario Power Generation

What is the budget for the first Darlington BWRX-300, and how much of it has been spent so far?

Sources

Canadian Nuclear Safety Commission, “Commission authorizes Ontario Power Generation Inc. to construct 1 BWRX-300 reactor at the Darlington New Nuclear Project site,” April 4, 2025. canada.ca
Canadian Nuclear Safety Commission, “Darlington New Nuclear Project,” project page, accessed Oct. 29, 2026. cnsc-ccsn.gc.ca
World Nuclear News, “Canadian regulator issues SMR construction licence,” April 2025. world-nuclear-news.org

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