Summary
On 1 May 2026, Ontario Power Generation lowered a 953-tonne steel-and-concrete
basemat module into a 35-metre shaft at the Darlington site east of Toronto —
the first physical construction step for the Western world's first grid-scale
small modular reactor (SMR). The unit is a GE Vernova Hitachi BWRX-300: ~300
MW, enough for roughly 300,000 homes, on a footprint that fits inside two
international soccer fields. Three more units are planned at the site for ~1,200
MW total (≈1.2 million homes). The significance isn't this one reactor — it's
that after a decade of SMRs being "five years away," someone finally poured
concrete on a grid-scale commercial unit. The real test is whether units #2–#4
come faster and cheaper than #1, which is the entire premise of the "modular,
factory-built" model.
Key points
- Reactor: GE Vernova Hitachi BWRX-300 — a ~300 MW boiling-water SMR, a
scaled-down derivative of proven BWR designs (de-risks the licensing vs a
brand-new reactor physics). - Milestone (1 May 2026): a crawler crane lowered the 953-tonne basemat
foundation module 35 m below grade into the excavated reactor shaft — the
first grid-scale SMR construction step in the West. - Output: ~300 MW / ~300,000 homes per unit; four units planned at
Darlington → ~1,200 MW / ~1.2 million homes. - Owner/operator: Ontario Power Generation (OPG), Darlington site, Ontario.
- Footprint: fits within ~two international soccer fields (~430 × 200 ft) —
the "small" in SMR is as much about siting flexibility as size. - Cost: first unit ~CAD 6.1 billion; full four-unit programme ~CAD 20.9
billion (~USD 15 billion, 2024 dollars). Estimated power cost ~14.9 ¢/kWh. - Timeline: repeat units targeted at 18–36 months each; grid connection
target end of 2030. - Why it matters: the modular bet is repeatability — stamp out standard
300 MW modules instead of bespoke gigawatt one-offs that run a decade late and
over budget. Unit #1 proves it can be built; units #2–#4 prove (or disprove)
the economics that the whole SMR thesis rests on. The headline cost (~15 ¢/kWh)
is not cheap, so the learning-curve question is everything.
Fact check
Not formally fact-checked. Headline figures (953 t, 35 m, 300 MW, ~300k homes,
4 units, end-2030 grid target) are internally consistent with OPG's public
Darlington SMR programme; cost figures (~CAD 6.1bn first unit / ~CAD 20.9bn
programme) are as reported by the source and worth confirming against OPG before
quoting.
| Claim | Verdict | Notes | Source |
|---|---|---|---|
| First grid-scale SMR under construction in the Western world | ⏳ Plausible | Widely reported as the first commercial grid-scale SMR build in North America / the West. | OPG / multiple outlets |
Related resources
| Type | Name | URL | Notes |
|---|---|---|---|
| 🗂️ | OPG Darlington New Nuclear Project | https://www.opg.com/projects-services/projects/nuclear/smr/ | Owner/operator project page |
| vendor | GE Vernova Hitachi BWRX-300 | https://www.gevernova.com/nuclear/carbon-free-power/bwrx-300-small-modular-reactor | Reactor design |
Full content
(click to expand)
Canada has lowered a 953-tonne steel-and-concrete foundation module into a
35-metre shaft at the Darlington site in Ontario, marking the first physical
construction step of the Western world's first grid-scale small modular reactor.
The unit is a GE Vernova Hitachi BWRX-300 (~300 MW, ~300,000 homes), operated by
Ontario Power Generation, with three further units planned (~1,200 MW total).
The first unit is budgeted at ~CAD 6.1 billion and the four-unit programme at
~CAD 20.9 billion (~USD 15 billion), with repeat units targeted at 18–36 months
each and grid connection by the end of 2030.