TL;DR
Ontario Power Generation says the first BWRX-300 reactor at Darlington, east of Toronto, will not meet its October 2030 target and will exceed its CA$7.7 billion budget. The utility has not provided replacement figures and expects a revised cost and schedule assessment by mid-2027.
Ontario Power Generation says the first BWRX-300 small modular reactor at its Darlington site will miss its October 2030 target and exceed its initial CA$7.7 billion budget. The utility has not announced a replacement completion date or cost, making the project’s revised outlook a major test for a reactor design being pursued in North America and elsewhere.
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In a Tuesday earnings release, the publicly owned Ontario utility said it is preparing an updated assessment of the project’s cost and schedule. Ontario Power Generation expects that work to be substantially completed by mid-2027. Until then, the utility has not published revised figures for either the reactor’s expected cost or when it might begin operating.
The project is at the Darlington site east of Toronto. The initial CA$7.7 billion estimate is approximately US$5.4 billion. It covers the first reactor, according to the project details reported in the announcement. The utility’s separate plan is to build four units for CA$20.9 billion; those figures describe a broader project and should not be confused with the initial budget for the first unit.
Ontario Power Generation said the schedule and cost update reflects ongoing engineering work by GE Vernova Hitachi Nuclear Energy on its first-of-a-kind reactor, with effects on construction execution and supply-chain performance. GE Vernova Hitachi said that engineering and design maturity are among several connected factors, alongside procurement, construction, inflation and geopolitical risks.
Darlington’s first SMR is delayed and over budget
Ontario Power Generation says the first BWRX-300 will miss its October 2030 target and exceed its initial budget. New cost and schedule figures are pending.
What is known
The first BWRX-300 is being built at Darlington, east of Toronto.
- The first unit will be late.
- It will exceed its initial budget.
- Ontario Power Generation is updating its cost and schedule assessment.
- A revised total cost.
- A new completion or operating date.
- The size of the overrun and delay.
Factors cited
The announcement points to connected engineering and delivery challenges.
Engineering maturity
Ongoing work on this first-of-a-kind reactor affects construction execution.
Procurement and construction
Supply-chain performance and construction are among the factors identified.
Inflation and geopolitical risks
GE Vernova Hitachi cited changing market conditions, without assigning a share of the impact.
Why other projects are watching
Darlington is the first BWRX-300 build and an early test of whether the design can be delivered predictably.
The mid-2027 assessment is expected to clarify cost and schedule.
Utilities, governments and developers can better judge the project’s delivery challenge.
Savings from building multiple units have not yet been demonstrated by an operating BWRX-300 fleet.
A Test for North American SMRs
The Darlington delay matters beyond Ontario because this is the first BWRX-300 being built and a prominent early test of whether a smaller reactor can be delivered on a predictable schedule and within a commercially workable budget. Utilities, governments and prospective project developers are watching whether the design can move from engineering plans to construction at scale.
Supporters of small modular reactors argue that repeatable designs and manufacturing in series could reduce costs and construction time as more units are built. But the claimed savings depend on a learning effect that has not yet been demonstrated by a fleet of operating BWRX-300s. A large cost or schedule increase at the first project could affect the willingness of other buyers and investors to proceed, although the extent of any effect is not known.
The project is also part of a wider effort to add electricity without direct carbon emissions as demand rises. Ontario Power Generation plans four units, and federal and provincial investment funds have committed up to CA$3 billion for minority stakes, according to the reported project details. Any change in project costs could have consequences for funding plans, but the new total has not yet been disclosed.
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How Darlington Reached This Point
Ontario Power Generation selected the BWRX-300 design in late 2021, when it said the reactor might be completed as early as 2028. The current target later became October 2030; the latest announcement says that date will not be met. The project is described as Canada’s first new nuclear build in more than three decades and the first BWRX-300 project.
The BWRX-300 is designed to produce 300 megawatts of electricity using light-water technology, the type used by most of the world’s existing nuclear fleet. The Tennessee Valley Authority received a U.S. construction permit for a BWRX-300 in September, while developer Blue Energy has begun the U.S. Nuclear Regulatory Commission application process for a proposed Texas project. Those developments show interest in the design; they do not establish that future projects will avoid the problems now reported at Darlington.
Cost and schedule overruns have affected other North American nuclear construction. Georgia Power’s Vogtle units 3 and 4, large AP-1000 reactors that entered service in 2023 and 2024, took seven years longer than planned and incurred an additional US$17 billion, according to the reported figures. Vogtle is not the same design or project, but it illustrates why investors and policymakers pay close attention to the first cost and schedule estimates for new nuclear builds.
“The update “reflects GE Vernova Hitachi (GEVH) Nuclear Energy’s ongoing engineering for its first-of-a-kind SMR, which has impacts on construction execution and supply chain performance.””
— Ontario Power Generation
Revised Cost and Schedule Pending
The size of the budget overrun and the length of the delay remain unknown. Ontario Power Generation has not released a replacement budget, a new operating target or a detailed breakdown of how much each factor has contributed. Its mid-2027 assessment is the next stated point for a fuller estimate, not a new promise that the reactor will be operating by a particular date.
The public announcement points to ongoing engineering, construction execution and supply-chain performance. GE Vernova Hitachi also cited procurement, construction, inflation and geopolitical risks. The available information does not assign a specific share of the delay or additional cost to any one of these factors, or say whether the four-unit plan’s total cost estimate will change.
It is also too early to determine how the Darlington experience will affect other proposed BWRX-300 projects. The reactor is a first-of-its-kind build, and later units could face different costs and conditions. Whether repeat construction would reduce costs remains unproven; the project’s updated figures should help clarify the scale of the challenge.
Mid-2027 Estimate Is the Next Milestone
Ontario Power Generation says it expects to substantially complete its revised cost and schedule assessment by mid-2027. That update should provide a clearer basis for judging the project’s expected total cost, construction timetable and any implications for the wider four-unit plan. The utility has not stated when it will publish final revised targets or whether interim updates are planned.
For other developers and public agencies considering the BWRX-300, the next key information will be whether Darlington’s revised estimate identifies specific engineering, procurement or construction changes and how those affect the remaining work. Until those details are released, the project’s wider implications for the design’s cost and repeatability remain uncertain.
Source: rss
Key Questions
Which reactor project is delayed?
The first GE Vernova Hitachi BWRX-300 unit at Ontario Power Generation’s Darlington site, east of Toronto, is delayed.
How much will the Darlington reactor cost?
The first unit will exceed its initial CA$7.7 billion budget, but Ontario Power Generation has not released a revised cost. The utility expects its updated assessment to be substantially complete by mid-2027.
When will the reactor begin operating?
It will not meet the October 2030 target. The utility has not provided a new operating date.
Does the delay affect all four planned reactors?
The announcement concerns the first Darlington unit. Ontario Power Generation plans four units, but it has not said whether the first unit’s delay will change the wider plan or its stated CA$20.9 billion cost for four units.
Why could the project matter to other SMR developers?
Darlington is the first BWRX-300 project, so its eventual cost and schedule may inform decisions about other proposed units. Whether repeated construction will lower costs remains unproven.
Source: canarymedia.com
