The long-awaited return to service of the refurbished unit 2 of the Bruce A nuclear power plant in Ontario, Canada, has been delayed due to damage in an electrical generator on the non-nuclear side of the plant.
Plant operator Bruce Power received permission from the Canadian Nuclear Safety Commission in mid-March to restart Bruce A unit 2 following the completion of refurbishment work on the 750 MWe Candu, which has been idle for almost 20 years. However, during recent preparations to synchronize the unit to the electrical grid, an unspecified incident occurred which caused "some damage" to the electrical generator on the non-nuclear side of Bruce's operations. The generator had been replaced as part of the refurbishment project by Siemens Canada. Bruce Power noted that the electrical protection system "worked as designed and the approach to connect to the grid was stopped."
|The turbine hall of Bruce A unit 2 (Image: Bruce Power)
Following initial inspections, Bruce Power said, "It is clear repairs will need to be made to this electrical generator." The company said that Siemens Canada would help assess the situation and then complete the repairs "as soon as possible." Bruce Power noted, "Although the unit 2 reactor is ready to operate, the repair to this non-nuclear system will have an impact on when unit 2 will be able to deliver electricity to the grid." It added, "This delay will not have an impact on Ontario's electricity system reliability due in part to the strong performance of Bruce Power's operating fleet, nor is it expected to materially change the cost of the restart project."
TransCanada Corporation, which owns 49% of Bruce A and 32% of Bruce B, said that the incident "will likely mean unit 2 will not be synchronized to the Ontario electrical grid as previously stated in the second quarter of 2012."
However, Mike Burke, vice president of Bruce A operations, commented: "While this is clearly seen as a setback, with this repair isolated to one non-nuclear system on unit 2, we can continue to advance the unit 1 work program." Unit 1 is expected to resume commercial operations during the third quarter of 2012.
The company noted that other activities at the Bruce A plant are proceeding as planned. Unit 3 is expected to be restarted "within days" following a C$300 million ($293 million) modernization program which began in November 2011. That program will extend the operating life of the unit by ten years. Meanwhile, in its latest operating cycle, Bruce A unit 4 has been operating continuously for almost 500 days.
Units 1 and 2 at the four-unit Bruce A plant started up in 1977, but unit 2 was shut down in 1995 because a steam generator suffered corrosion after a lead shielding blanket used during maintenance was mistakenly left inside. In the late 1990s then-owner Ontario Hydro decided to lay up all four units at the plant to concentrate resources on other reactors in its fleet, and unit 1 was taken out of service in December 1997 with units 3 and 4 following in 1998. The four units at sister power station Bruce B continued to operate. Bruce Power took over the operations of both Bruce plants from Ontario Hydro in 2001 and restarted units 3 and 4 by early 2004. Bruce A units 3 and 4 are likely to undergo refurbishments once units 1 and 2 are back in operation.
The decision to refurbish the units followed a 2005 agreement by Bruce Power and the government of Ontario to refurbish the two 750 MWe Candu reactors as a faster option than building new ones in the face of impending power shortages.
Candu reactors are designed to undergo refurbishment after approximately 25 years of operation, requiring a major outage but allowing reactor life to be extended by up to 30 years.
Researched and written
by World Nuclear News