Bruce B planned Vacuum Building Outage begins in close collaboration and co-ordination with system operator, Hydro One

With all four of Bruce B’s operating units removed from service, the generating station’s planned Vacuum Building Outage (VBO) began on April 24 in close collaboration and co-ordination with the Independent Electricity System Operator (IESO) and Hydro One.

The VBO represents an investment of $190 million over less than three weeks to ensure maintenance and inspection work can be carried out safely and successfully by Bruce Power, its partners and skilled tradespeople.

Vacuum buildings are unique to multi-unit CANDU generating stations and are part of their robust safety systems, providing an additional protective barrier to the release of radioactivity to the environment. All four operating units must be shut down approximately once every decade to allow for inspections and maintenance to the vacuum building, the culmination of extensive planning, resourcing and co-ordination.

“Bringing all of the station’s operating units off-line at once is a large undertaking and our team has been planning for years to ensure it is completed safely,” said Adrian London, Vice-President, Bruce B. “The Vacuum Building Outage removes about 15 per cent of the capacity available to the Independent Electricity System Operator grid, so the people of Ontario are counting on us to bring our units back online successfully to continue to provide clean, reliable power.”

Bruce Power works closely with the IESO to ensure the timing of these outages can be accommodated to meet the needs of the province’s electricity grid. VBOs are scheduled during periods of the year when demand is expected to be low – usually the spring or fall. This allows Bruce Power to make sure its units will be operational for the summer peak period, providing about 30 per cent of Ontario’s electricity with zero carbon emissions at a time when reliable energy is needed most.

Prior to being taken off-line April 18 for a planned outage, Unit 7 marked its historical record run of 646 consecutive days operation, which is the eight-unit Bruce site’s second longest after Unit 1’s post-refurbishment run of 694 days in 2020.

About Bruce Power

Bruce Power is an electricity company based in Bruce County, Saugeen Ojibway Nation Territory, Ontario. We are powered by our people. Our 4,200 employees are the foundation of our accomplishments and are proud of the role they play in safely delivering clean, reliable nuclear power to families and businesses across the province and cancer-fighting medical isotopes around the world. Bruce Power has worked hard to build strong roots in Ontario and is committed to protecting the environment and supporting the communities in which we live. Formed in 2001, Bruce Power is a Canadian-owned partnership of TC Energy, OMERS, the Power Workers’ Union and The Society of United Professionals. Learn more at and follow us on Facebook, Twitter, LinkedIn, Instagram, TikTok and YouTube.