Skip to Content

As more sectors of Ontario’s economy move toward electrification, there will be a growing demand for clean electricity.

That’s why OPG is exploring innovative energy options to power Ontario's future – including advancements in reliable, virtually carbon-free nuclear power, which can help meet Ontario’s changing energy needs while combating climate change.

OPG’s Darlington Nuclear station is already an important part of Ontario’s clean energy future – the station provides close to 20% of Ontario’s electricity, and the Darlington Refurbishment Project will ensure this world-class generator continues to provide reliable power for decades to come.

In parallel, as Canada’s only site licenced for new nuclear with a completed and accepted Environmental Assessment (EA), the Darlington Nuclear site offers a significant solution to secure Ontario’s clean energy future.

On Nov. 13, 2020, OPG announced we are paving the way for a clean energy future by resuming planning activities for additional new nuclear generation at the Darlington site, by siting a Small Modular Reactor (SMR).

OPG resumes planning activities for Darlington New Nuclear

Share this video:

Questions & Answers

On Nov. 13, 2020, OPG announced resumption of planning activities for Darlington New Nuclear, with the goal of hosting a Small Modular Reactor (SMR) as early as 2028.

OPG’s Darlington Nuclear station is already an important part of Ontario’s clean energy future – the station provides close to 20 per cent of Ontario’s electricity, and the Darlington Refurbishment Project will ensure this world-class generator continues to provide reliable power for decades to come.

OPG currently holds a Site Preparation Licence, granted by the Canadian Nuclear Safety Commission (CNSC). To construct and operate a new reactor, further approvals, including additional CNSC licences, would be required. These licences must be obtained through an extensive regulatory process, which would include the opportunity for public input and a public hearing.

One of OPG’s current priorities is the successful renewal of the Site Preparation Licence, which was granted in 2012 and will expire in 2022. Our application will be considered by the CNSC at a public hearing in June 2021. OPG will continue Indigenous and public outreach and communications in support of the licence renewal hearing and other project information as it becomes available.

The CNSC invites public participation in the hearing and has made available participant funding. Visit the CNSC’s website for more information on how to participate.

SMRs have both a smaller footprint and smaller energy output than conventional reactors, like the CANDU units currently operating at both Darlington and Pickering Nuclear Generating Stations. But unlike traditional reactors, SMRs are modular in that they are often factory constructed, with the ability to add modules to meet changing energy needs.

OPG’s current fleet of CANDU reactors each generate between 500 and 900 megawatts (MW). SMRs are smaller, ranging in size from about 1 MW to about 300 MW.

CANDU reactors and SMRs both use fission to create heat which is used to generate electricity.

No decision on technology has been made yet; however, OPG has begun work aimed at identifying potential options. In October, OPG announced advancement of engineering and design work with three grid-scale SMR developers: GE Hitachi, Terrestrial Energy and X-energy.

Work with the three developers continues and will help inform OPG on potential options for future deployment. While OPG is now working with the three developers, a technology partner has not been selected. OPG continues to be open to potential opportunities, including from other developers, in particular if they offer a strong business case that can meet our considerations and requirements for a future project.

As no decisions have been made on the technology to be used, a precise estimate is not yet available. Any business case decision would be made with ratepayers in mind. The project would need to show benefit from an economic perspective, support the conclusions of the completed environmental assessment, and have the potential to be used by other Canadian jurisdictions, to achieve economies of scale and support the potential export market.

A study undertaken by the Conference Board of Canada shows strong economic benefit to Ontario from construction and 60 years of operation of a single unit in the province. According to the report, direct, indirect and spin-off related employment would result in an annual average of approximately: 700 jobs during project development; 1,600 jobs during manufacturing and construction; 200 jobs during operations; and 160 jobs during decommissioning. It would have a positive impact on direct, indirect and induced Gross Domestic Product of more than $2.5 billion and result in an increase of provincial revenues of more than $870 million.

For planning purposes, OPG envisions new nuclear capacity at Darlington as early as 2028, which will provide a new source of carbon free nuclear energy for Ontario’s future projected energy demand and support potential for deployment of SMRs to other Canadian jurisdictions interested in reducing fossil fuel use.

To meet this timeline, OPG is aiming to decide on an SMR technology by the end of 2021.

OPG has operated in Durham Region for more than 50 years, and in Clarington for more than 30 years. We have earned strong community support across Durham with our safe operations, and the multi-billion dollar refurbishment of the existing units at Darlington, a project currently tracking toward completion safely, on time, and on budget. Darlington is the only site in Canada with a licence for new nuclear build and with an approved EA.

We have both the operational know-how and the project management expertise for the new nuclear project. Beyond this, deployment of SMRs in Ontario would capitalize on the existing nuclear supply chain in this province, and could enable other provinces to transition from coal; provide alternative energy options to benefit carbon intensive industries; drive national job creation and innovation; facilitate deep, economically sustainable reductions in greenhouse gas emissions; and accelerate the transition from fossil fuels to a zero emissions electrical grid in Canada.

It is possible an SMR could be operating as early as 2028.

No. On Dec. 1, 2019, the Provinces of Ontario, New Brunswick and Saskatchewan signed a Memorandum of Understanding (MOU) setting a framework for action on the deployment of SMRs in their respective jurisdictions. In August 2020, Alberta also signalled its intention to enter into the MOU.

Just like many other industries, nuclear technology continues to evolve and innovate. All SMR designs are evolutions of previous reactor technologies which have operated safely. These next-generation reactors have additional enhanced safety features based upon decades of world-wide reactor operating experience.

All technologies include advanced, passive safety attributes that make them even safer than the designs in operation today. Any SMR project will require licensing by the CNSC, which involves comprehensive review of the reactor design and assessment of the safety case to ensure protection for the public and environment.

Related news
Media release

OPG commits to being a net-zero company by 2040

OPG's Climate Change Plan includes ambitious goals aimed at driving efficient, economy-wide decarbonization and economic renewal.

Read more
Our stories

Planning resumes on Darlington New Nuclear to help secure Ontario’s clean energy future

OPG’s Darlington Nuclear site in Clarington could soon be home to one of the province’s first Small Modular Reactors.

Read more
Media release

OPG resumes planning activities for Darlington New Nuclear

Today OPG announced resumption of planning activities to construct a grid-size Small Modular Reactor at our Darlington site in Clarington.

Read more
Results 1-3 of 8

Chronology of Darlington New Nuclear

A chronology of Darlington New Nuclear key activities and milestones including relevant documents.

On Nov. 13, 2020, OPG was joined by Provincial government and local municipal and business leaders to announce that planning activities will resume to construct a Small Modular Reactor at OPG's Darlington site in Clarington.

The CNSC has issued a Notice of Public Hearing and Participant Funding for OPG’s application to renew the DNNP Site Preparation Licence

OPG has submitted an application to the Canadian Nuclear Safety Commission (CNSC) seeking renewal of the licence that allows OPG to undertake site preparation activities required for new nuclear generation at OPG’s Darlington site.

OPG currently holds a Site Preparation Licence for the Darlington Nuclear site, the first of a series of licences that would be required for additional nuclear generation capacity. The current 10-year licence was obtained following the completion of comprehensive environmental impact studies and an extensive public hearing conducted by a Joint Review Panel of the CNSC and the Canadian Environmental Assessment Agency in 2012.

OPG has not yet undertaken any licensed activities on the site. However, the existing licence allows OPG to carry out activities to prepare the site for future construction, for example:

  • Clearing and grubbing vegetation
  • Excavation and grading of site
  • Installing services and utilities required to service the future project facilities (e.g., domestic water, fire water, sewage, electrical, communications, natural gas)
  • Constructing support buildings

As the licence expires in 2022, renewing the licence will help maintain the option for reliable, low carbon nuclear energy to remain a key part of Ontario’s low-emission energy mix.

With the application submitted, the CNSC will determine the timing and process for review. A decision by the commission members is expected in 2021. The application and supporting documents are available here:

  • OPG issues notification to the CNSC of our intent to apply to renew the site licence that is set to expire in August 2022.
  • OPG submits a licence Mid-Term report to the CNSC, outlining the activities undertaken since the licence was granted as well as a report providing an update on the commitments made by OPG (updated April 2019) during the licencing process.
  • OPG continues to maintain the licence in accordance with the licence conditions.
  • Citing lower than planned power consumption growth combined with a strong supply situation, the Government of Ontario, through the 2013 Long-Term Energy Plan, requests that OPG defer the construction of new nuclear reactors but maintain the existing licence.
  • The CNSC issues the Licence to Prepare Site to OPG for a period of 10 years, valid from August 17, 2012 to August 17, 2022.
  • The Government of Canada issues a response accepting the recommendation of the Joint Review Panel and accepting the Environmental Assessment (EA).
  • As required by the Canadian Environmental Assessment Act (1992), an Environmental Assessment (EA) of the proposed project is conducted, including comprehensive studies undertaken by OPG and consultation with Indigenous communities, local community members and the broader public.
  • The Government of Ontario, OPG’s shareholder, directs OPG to initiate the federal approvals process for new nuclear generating units in response to recommendations from the Ontario Power Authority’s Integrated Power System Plan.
  • The Plan calls for investment in new nuclear generation capacity in order to maintain Ontario’s nuclear generating capacity at 14,000 MWe, consistent with nuclear energy’s share of the 2005 supply mix.
An aerial view of the Darlington Nuclear Generating Station.

Darlington New Nuclear documents

Accessible versions available upon request to

Canadian Nuclear Safety Commission’s licensing process for nuclear power plants

The Canadian Nuclear Safety Commission (CNSC) is mandated, under the Nuclear Safety and Control Act (NSCA), to regulate all nuclear facilities and nuclear-related activities; including the possession, use, and transport or storing of nuclear substances in Canada.

The CNSC Information Guide “Licensing Process for New Nuclear Power Plants” provides an overview of the licences required for the various phases of a nuclear power plant lifecycle, including the many opportunities for Indigenous and public participation.