Bruce Power and its partners have completed the bulk of the construction phase of the major component replacement (MCR) outage at Bruce unit 6 and are transitioning to activities to bring the unit back online in the fourth quarter of 2023. Meanwhile, Ontario Power Generation (OPG) is preparing to start work on its third reactor refurbishment and is on track to complete all four by 2026.

Refurbishment work at Bruce 6 (Image: Bruce)

Unit 6 is the first of six Bruce reactors to undergo MCR as part of the company's Life-Extension Program, a long-term investment programme to update all eight Bruce reactors and secure the site's operation until 2064. The MCR of unit 6 - which includes the replacement of key reactor components such as steam generators, pressure tubes, calandria tubes and feeder tubes - began in January 2020. Units 1 and 2 have already been refurbished.

"Bruce Power and its partners have completed the bulk of the construction phase of the Unit 6 MCR outage and will transition to return-to-service activities in 2023 to bring the unit back online in the fourth quarter, providing the people, businesses and hospitals of Ontario with clean and reliable electricity for decades to come," the company said in its latest update on the project.

Refilling of the unit's moderator system, which circulates heavy water through the calandria to remove moderator heat during reactor operation, was completed on December 6, in a major milestone for the project.

In November, the reactor area bridges were reinstalled in the Unit 6 vault. The reactor area bridges carry fuelling machines to all units for fuel bundles to be installed and removed while the reactor is online, a feature unique to CANDU reactors.

The company said it is now in the final stages of preparation for the unit 3's MCR outage, which is scheduled to begin in March.

Darlington progress

OPG said work at its Darlington plant, where a similar major programme to refurbish all four of the site's Candu units, continues on time and on budget. The 10-year, CAD12.8 billion (currently about USD9.5 billion) project began in 2016 and is now past the half-way stage.

Two units - Darlington 3 and 1 - are currently undergoing refurbishment. Unit 3's refurbishment began in 2020 and is now 84% complete and moving towards fuel loading, the company said. Reassembly of the unit's core was completed in July, and static commissioning for turbine control modifications was completed in September. The Canadian Nuclear Safety Commission recently removed a regulatory "hold-point" clearing the unit for fuel reloading.

Darlington 1's refurbishment began in February 2022 and is currently 25% complete. Removal of the unit's 960 feeder tubes was completed in November, and reactor disassembly work continues, leading to removal of the bellows and endfittings which the company said is the first step in fuel channel disassembly.

Darlington 2 has already been refurbished and returned to service in June 2020. Planning is underway for unit 4's refurbishment, which is scheduled to begin in July, incorporating lessons learned from the previous refurbishments. Refurbishment of all four units remains on track for completion in 2026, the company said.

Researched and written by World Nuclear News