Refurbished Candus make headway towards restart

25 May 2023

Fuel loading has been completed at Bruce 6, keeping the project on track to resume operation later this year. Meanwhile, Canada's nuclear regulator has given the go-ahead for Ontario Power Generation (OPG) to restart Darlington 3.

Darlington 3 reactor face (Image: OPG)

Canadian Nuclear Safety Commission (CNSC) Executive Vice-President and Chief Regulatory Operations Officer Ramzi Jammal notified OPG by a letter dated 20 May that the regulator had concluded that OPG has met all its requirements for the removal of the second regulatory hold point for the project, allowing the refurbished reactor to leave the so-called guaranteed shutdown state, or GSS. "OPG may now proceed with surrendering GSS to restart the refurbished reactor at low power for testing and verification," Jammal said.

This follows the regulator's removal of the first hold point last December, allowing OPG to proceed with fuel loading at the reactor. Hold points are mandatory checkpoints where CNSC approval is required before the licensee can move on to the next stage of the process to return the unit to operation. Two further regulatory hold points remain before Darlington 3 can reach criticality and return to service.
Unit 3 is the second of four Candu reactors at the site to undergo refurbishment in a project with a 10-year execution phase, following unit 2 which returned to service in April 2020. Refurbishment of Darlington 3 began in September that year and is slated for completion in the first quarter of 2024. Refurbishment of unit 1 began in February this year, with completion expected in the second quarter of 2025, with refurbishment of Darlington 4 scheduled to begin in the third quarter of 2023.

Bruce fuel loading

Bruce Power announced that fuel loading at Bruce 6 has now been completed ahead of schedule. This follows CNSC's removal of the first regulatory hold point for that project on 10 May.

"Operations and Maintenance crews loaded 5,760 fuel bundles into the reactor core, safely completing the task ahead of schedule. Each fuel bundle contains 37 fuel rods, which are packed with Canadian-made uranium oxide pellets from Bruce Power partner Cameco. One bundle produces clean electricity that is equivalent to 400,000 kg of coal or 400,000 cubic metres of natural gas," the company said.

The unit is the first of six at the Ontario site to undergo refurbishment between 2020 and 2033. Bruce 3 became the second unit to begin the process - referred to as Major Component Replacement, or MCR - in March this year when it was taken offline for defueling.

The multi-billion dollar refurbishment projects ensure a further 30 years of operation for each Candu reactor.

Researched and written by World Nuclear News