Twenty-year renewal sees Darlington become longest-licensed Canadian plant

The Canadian Nuclear Safety Commission (CNSC) said it made its decision to renew the licence for the four-unit Candu plant after considering submissions from Ontario Power Generation (OPG), CNSC staff and 79 intervenors during a two-part public hearing held earlier this year, saying it concluded that "OPG remains qualified to carry on the activities that the renewed licence will authorise".

There are no changes to OPG's licensed activities under the renewed licence, the CNSC said, although the decision includes a requirement for OPG to provide two comprehensive performance updates to the Commission on the conduct of its licensed activities, as well as a new licence condition that requires OPG to continue its engagement with Indigenous Nations and communities throughout the licence period.

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.

Three of the four units at Darlington are currently in operation, having undergone refurbishment. The fourth unit is due to return to service in 2026, completing a 10-year execution phase which OPG says has exceeded all safety, quality, schedule, and financial forecasts.

"The longest-ever licence term for a Canadian nuclear station reflects the strong performance of the Darlington station, the proficiency of our highly skilled workers, and OPG's continued commitment to safety and operational excellence," OPG President and CEO Nicolle Butcher said. "Under this licence, Darlington will continue to safely and reliably produce electricity to help meet Ontario’s energy needs for decades to come."

The plant's current licence expires on 30 November.