OPG set to revise timeline and cost of first SMR unit

The company has previously acknowledged that the Darlington New Nuclear Project (DNNP) is "subject to inherent risks and uncertainties that could affect project cost and schedule".

Announcing its financial and operating results for the third quarter of 2026, Ontario Power Generation (OPG) said: "While OPG is undertaking a comprehensive assessment of the project cost and schedule, DNNP Unit 1 is no longer expected to achieve the previously disclosed commercial operation date target of October 2030 or be completed within the previously disclosed estimated cost of CAD7.7 billion (USD5.4 billion), inclusive of required systems and services that would be common to all SMRs planned as part of the project."

OPG said the delay and cost overrun "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. OPG is working with GEVH to complete outstanding engineering scope and move the project forward as quickly as possible".

It said the assessment of the project cost and schedule will be "informed by the completion of engineering scope, including construction deliverables". The assessment will also include further evaluation of engineering design maturity and completion timelines, first-of-a-kind design complexity impacts on construction and procurement assumptions, updated market conditions including inflationary and geopolitical risk, other residual risks, and the effectiveness of mitigation and recovery actions.

"We have made meaningful progress in building the G7's first small modular reactor, and critical work continues every day on site," said OPG President and CEO Nicolle Butcher. "At the same time, we have identified risks that will impact Unit 1's schedule and budget. As we continue construction, we are working to fully assess those impacts, and establish mitigation measures and a cost and schedule outlook that we can stand behind. As work progresses, we will share the information transparently."

"While engineering and design maturity are important considerations, as OPG's update recognises, there are multiple interconnected contributions across engineering, procurement and construction, as well as evolving market conditions, including inflation and geopolitical risks," GE Vernova Hitachi spokesperson Jonathan Allen was quoted as saying by The Globe and Mail.

OPG said it expects to "substantially complete" the comprehensive assessment of the projected cost and schedule by mid-2027.

Background

GE Vernova Hitachi Nuclear Energy's BWRX-300 is a 300 MWe water-cooled, natural circulation SMR with passive safety systems that leverages the design and licensing basis of GE Vernova Hitachi Nuclear Energy's US Nuclear Regulatory Commission-certified ESBWR boiling water reactor design and its existing, licensed GNF2 fuel design.

_{An illustration of how the completed BWRX-300 could look (Image: OPG)}

The Darlington New Nuclear Project will be the first new nuclear build in Ontario in more than three decades. OPG received a Licence to Construct the first of four planned BWRX-300s at Darlington from the CNSC in April 2025. The following month the Province of Ontario approved the CAD20.9 billion (USD15 billion) budget and the start of construction for the first of the proposed four SMRs at the site.

Ontario's Ministry of Energy and Mines said its approval of OPG's plan would create up to 18,000 Canadian jobs and inject CAD500 million annually into the Ontario economy, with the construction, operation and maintenance of the four units set to add CAD38.5 billion to the country's GDP over 65 years. It said the provincial government and OPG have worked together to ensure that 80% of project spending goes to companies in Ontario.

Site preparation works began in the autumn of 2022, and several long-lead items, including the reactor pressure vessel, have already been procured. The giant Basemat module, which will serve as the foundation of the reactor building, was set into place 35 metres below ground in the excavated reactor building shaft in April (see top picture).