Darlington New Nuclear — BWRX-300 Unit 1

Current state

Notes

First grid-scale SMR construction in the West; the FOAK cost/schedule ⁠benchmark for the entire BWRX-300 order book (Poland, TVA, SK). Delivery model is an OPG/GEH/AtkinsRealis/Aecon alliance rather than a single EPC — epc field left null pending a canonical designation.

Milestone log

• 2025-04-04 — CNSC licence to construct granted; OPG/Ontario approved ~C$20.9bn for four units (source)
• 2026-06-24 — OPG applied to CNSC for 20-year operating licence — would be first operating SMR in a G7 country (source)
• 2026-07-01 — Unit 1 reactor building shaft excavation past 80%; reactor pressure vessel in manufacturing (source)
• 2026-03-25 — Correction: OPG submitted the Licence to Operate application on 2026-03-25 per the CNSC timeline (the 2026-06-24 entry above carried a reporting date) (source)
• 2026-03-30 — CNSC cleared Regulatory Hold Point-1 (reactor building foundation); civil construction of the reactor building authorized (source)
• 2026-08-01 — Summer 2026 progress (OPG roundup; exact date N/A): reactor-building basemat placed, first two diaphragm-plate shaft rings installed, ~4,000 m3 forebay concrete, TBM main drive installed ahead of fall tunnelling (source)

The milestone log is append-only: corrections are recorded as new entries, never rewrites. Full history via /api/v1/changes.

NNN coverage

Sources

1. https://www.gevernova.com/nuclear/carbon-free-power/bwrx-300-small-modular-reactor/bwrx-300-darlington-ontario
2. https://www.opg.com/
3. https://www.opg.com/projects-services/projects/nuclear/smr/darlington-smr/
4. https://www.cnsc-ccsn.gc.ca/eng/reactors/new-reactor-power-plant-projects/new-reactor-power-plant-facilities/darlington-new-nuclear-project/