Ontario Power Generation (OPG) said the four-unit CAD12.8 billion (USD9.4 billion) Darlington Refurbishment Project - which extends the plant's operation by another 30 years - had been completed CAD150 million under budget and four months early.
Unit 4 was taken offline in July 2023 for refurbishment, which was completed in 968 days, the quickest of the four units. OPG says about 8000 lessons have been learned from the refurbishment project.
Nicolle Butcher, OPG’s President and CEO, said: "Through this project, we have demonstrated to the world that complex nuclear projects can be completed successfully, ahead of schedule and under budget. Our experience on this refurbishment, and the thousands of lessons we have learned, will serve as our foundation as we advance the future of nuclear. Darlington’s refurbishment has given us the confidence, the tools, and the skills to forge ahead."
Candu units are pressurised heavy water reactors designed to operate for 30 years before refurbishment. Refurbishment is a major undertaking: it includes the replacement of key reactor components such as steam generators, pressure tubes, calandria tubes and feeder tubes, and involves removing all the reactor's fuel and heavy water and isolating it from the rest of the power station before it is dismantled. Thousands of components are inspected before the plant is rebuilt and is ready for another 30 years of operation.
Unit 2 was the first to be refurbished and returned to service in June 2020; unit 3 returned to service in July 2023; and unit 1 returned to service in November 2024.
Financial results
Meanwhile OPG reported its financial results for 2025 on 12 March, saying that net income attributable to the shareholder (it is owned by the Ontario government) was CAD1.5 billion, up CAD521 million on 2024.
It said: "The increase was primarily attributable to higher earnings from the Regulated - Nuclear Generation business segment, reflecting lower operating, maintenance and administration expenses, mainly due to fewer planned cyclical outage activities and the cessation of commercial operation of Unit 1 and Unit 4 of the Pickering GS in the fourth quarter of 2024 as planned, and higher revenue as a result of higher nuclear electricity generation."
Future plans
A major refurbishment project of Pickering units 5-8 got the go-ahead from the provincial government in November and OPG said the four units will be removed from service at the end of the third quarter this year.
It says that following defuelling, the refurbishment project will begin in January 2027 with unit 5 expected to return to service in 2031, and all four back by 2034. The approved budget to refurbish the four units is CAD26.8 billion (USD19.1 billion), "including interest, cost escalation, and contingency".
The Pickering generating station (Image: OPG)
Pickering units 5-8 - known as Pickering B - began operations in the mid-1980s and had been scheduled to end electricity production last year, but in 2022 the provincial government directed OPG to keep them in operation until 2026 and to reassess the feasibility of refurbishing the units. The government gave OPG the go-ahead to begin the initiation phase of the refurbishment project in January 2024, and one year later, it gave its permission for the start of the project definition phase.
According to a study by the Conference Board of Canada, the mega-project - which will enable the plant to continue in operation for up to 38 more years - will increase Ontario's GDP by CAD38.2 billion in 2024 dollars over the project's lifespan, including CAD17 billion during the refurbishment phase, and increase Canada's national GDP by CAD41.6 billion over its lifespan.
Butcher said: "We have the talent and experience, honed during the Darlington Refurbishment and ready to transition to this project, to deliver Pickering Refurbishment within budget and make it as successful as Darlington's."
Pickering units 1 and 4 - the four units making up Pickering A - ceased commercial operations in 2024.
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