Independent study

Will Darlington SMR Unit 1 be in commercial operation by the end of 2030?

Ontario Power Generation is building the first BWRX-300 small modular reactor at Darlington, Ontario. It is the first grid-scale SMR under construction in the G7. We worked only from 41 dated public sources. Schedule Studio built the plan, and Insights forecast it and tested six decisions. The 16-page study shows what each decision buys back and the latest date to take it.

OPG's target

End 2030

commercial operation of Unit 1

Most likely date

Aug 2032

with no intervention, as the plan stands

Time to win back

283 days

with six decisions taken in time

With all six

Nov 2031

most likely date of commercial operation

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The 16-page study (PDF)
The full plan behind the forecast (Primavera P6 XER)

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What we did

Built and forecast end to end with nPlan's products

Schedule Studio built the plan from OPG filings, regulator records and the trade press. Insights forecast it from the record of more than a million past projects. Then Insights tested each of six decisions as a separate forecast.

Built from public sources

OPG's filings with the Ontario Energy Board and its quarterly reports set the plan dates. The CNSC licence and hearing record set the regulatory steps. Vendor releases fix the reactor vessel, the modules and the tunnel.

A plan a bidder would recognise

The plan has 1,886 work items and 2,301 links in 11 packages. It runs from the licence to construct to commercial operation, with the cooling water tunnel, the switchyard and fuel load.

Three dates for every milestone

Each milestone has an early date, a most likely date and a late date. There is a 1 in 10 chance of a date outside each side. The data date is 28 October 2026.

Six decisions, each tested

Each decision is a separate forecast in Insights. For each one, the study gives the time it buys back, the latest date to decide, and how hard it is.

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What we found

Five findings from the study

283 days

can be won back with six decisions

Six decisions can win back about nine months

Left as it is, the plan reaches commercial operation most likely on 12 August 2032. The range runs from 1 March 2032 to 14 March 2033, with a 1 in 10 chance outside each side. With all six decisions, the most likely date moves to 3 November 2031. That is a projection of the plan, not a prediction of what OPG will do.

127 days

won back by early commissioning readiness

Commissioning readiness buys back the most time

Testing, fuel load and power ascension take the last two years before commercial operation. First-of-a-kind testing has the widest spread in the forecast. A ready team, tested procedures and trained operators remove much of that spread. The decision can wait until 4 June 2027.

25 Nov 2026

the first decision windows close

The first decisions are due within weeks

Secure tunnelling crews and key trades by 25 November 2026, and the forecast wins back 73 days. Bigger modules for Levels 3 to 8 must be decided by 24 November 2026. Four of the six decisions are due before 1 December 2026.

5 weeks

of spare time on the cooling water tunnel

The tunnel limits the gains on the reactor building

In the plan, the cooling water tunnel has only 36 to 38 days of spare time. So the reactor building can gain only about five weeks before the tunnel sets the date. With the tunnel secured, the reactor building decisions add more. Together, the six decisions win back more than the sum of their single gains.

6 of 9

past milestones where our date was nearer than the plan

We checked the forecast against what already happened

We made the first forecast from the investment decision of 8 May 2025. Then we checked it against nine milestones that OPG or the CNSC dated later. Our most likely date was nearer to the actual date than the plan in six cases, and equal in two. Five actual dates came after our late date. Two of those have only a quarter as their date. First-of-a-kind work needs a wider range, and the study says so.

Your programme

Run the same forecast on your own programme

We built everything on this page in a few days, working only from public information. With your own plan, the forecast and the decisions update every time you report progress. Your team sees which decisions protect the date while there is still time to take them. If you want to see it on one of your projects, talk to us.

Talk to us

nPlan produced this study without any involvement from, data from, or endorsement by Ontario Power Generation, GE Vernova Hitachi Nuclear Energy, AtkinsRéalis, Aecon, Kiewit, BWXT or the Canadian Nuclear Safety Commission. Every input is public. Dates and logic are nPlan's own estimates, not OPG's programme. Company and project names belong to their owners and identify only the subject of the study.