Bruce Power Ontario Bruce 3 reactor back

NEW YORK, Nov 10 (Reuters) - Bruce Power LP's 750-megawatt Unit 3 at the Bruce nuclear power station in Ontario returned to service on Nov. 9, the company said in a release.

The unit shut by Sept. 8 for a planned inspection of the vacuum building.

The vacuum building is designed to prevent the release of radioactive material to the environment in the unlikely event of an accident.

It is a large cylindrical structure connected to the generating station by a pressure relief duct and kept at negative atmospheric pressure so any potential release of radioactive steam can be sucked into the structure.

The Canadian Nuclear Safety Commission requires inspections of the structure every 12 years.

Unit 4 remained shut by Sept. 5 for planned maintenance and will likely return in mid November.

Unit 4 last shut for maintenance from about March 26-April 27, 2008. It is on an 18-month maintenance cycle.

All of the other units remained in service.

The 6,261 MW Bruce station is located in Tiverton on the eastern shore of Lake Huron about 155 miles (250 km) northwest of Toronto. There are four 750 MW units, 1 to 4, at the A station, which entered service in 1977-1979, and three 822 MW units, 5 to 7, and one 795 MW unit, 8, at the B station, which entered service in 1984-1987.