The Canadian Nuclear Safety Commission (CNSC) requires that the vacuum buildings at Pickering be inspected every 10 years. This requires the shutdown of all the nuclear units linked to the vacuum building.
The timing of the inspection is coordinated with the Independent Electricity System Operator to minimize the impact on the supply of electricity in Ontario. Spring is chosen because electricity demand is lower than in the summer or winter, the company said.
During the shut down more than 1,900 additional staff will be on site to assist the 2,730 regular station personnel. In all, they will perform 40,000 tasks related to the vacuum building inspection and maintenance.
At Pickering, Units 4, 5, 6 and 7 are expected to be back in service in six to eight weeks. Units 1 and 8 will remain out of service for an extended period as part of their scheduled maintenance programs.
The company said that the vacuum building is a safety feature that is unique to Candu technology. The interior of the circular building is kept at a pressure level close to a vacuum. Ducts link it to the operating nuclear units.
According to the company, in the extremely unlikely event of an accident, the resulting steam would be drawn into the vacuum building where it would be contained and doused with water. This would prevent the release of radioactive material to the environment. Pickering A and B share one vacuum building for which both stations will be taken out of service.
In 2009 Pickering Nuclear produced 12% of the province’s electricity. OPG recently announced it would invest $300m for the continued operation of the station.
