Final calandria* tube removed from Unit 1

 

*A calandria is the reactor core of the CANDU reactor.

(continued)

Duncan Hawthorne

Milestone marks end of disassembly phase in project to restart pair of Bruce A reactors

The 480th and final calandria tube was removed from the Unit 1 reactor late Wednesday, marking the end of the disassembly phase in the massive project to restart Units 1 and 2 at the Bruce A generating station.

Using custom-designed robotic tools, crews from Atomic Energy of Canada Limited (AECL) were able to complete the calandria tube removal on Unit 1 in less than a month, roughly four times faster than in Unit 2.

"The completion of this series marks the end of the most challenging part of this project," said Duncan Hawthorne, Bruce Power's President and Chief Executive Officer. "Having done so, and with a solid team behind us, our expectation going forward is that we can now work towards the successful rebuild and return-to-service of these units."

Each unit holds 480 calandria tubes, which lie horizontally inside the reactor and contain the pressure tubes, which in turn hold the uranium fuel bundles. Radioactive after years of service, these tubes were painstakingly removed using a series of robotic tools controlled by tradespeople working outside the reactor vault in a control centre outfitted with video feeds and computers to manipulate the tools.

"Think of it like heart transplant surgery in which the doctor has to operate from a completely separate room, using custom-made instruments that he controls remotely with a camera lens to serve as his eyes," Hawthorne said. "From a pure engineering perspective, it has been an amazing process of continual learning and refinement."
To complete this phase of the restart, a specialized tool was latched onto the west face of each reactor so it could push the tubes, one at a time, while another tool pulled from the opposite end. Guided into transfer cans, which served as contamination barriers, the six-metre long tubes were then picked up by a crane-like Remote Tool Carrier and swung onto narrow pallets.

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05/03/2009 11:24 AM


To minimize the amount of radioactive waste, the tubes were then fed into a special press, which crushed and cut the tubes into small pieces about the size of a credit card. Each of these pieces were then carefully stored in custom containers and shipped across site to the Western Waste Management Facility.

"We have reached this important milestone through the combined effort and talents of Bruce Power and AECL employees," said Hugh MacDiarmid, President and Chief Executive Officer, AECL. "By applying many of the lessons learned from our work on Unit 2, we have overcome challenges and modified our tool sets to complete the calandria tube removal safely and in record time."

With the old calandria tubes now gone, retube crews are preparing the reactor vessels to accept new calandria tubes with an eye to returning both units to service in 2010.

This latest milestone comes more than a year after the 16th and final replacement steam generator was lifted into Bruce A, completing one of the other major elements in the restart project. Using a massive crane brought in from Alberta specifically for the job, crews lowered the final 100-tonne boiler into place last January, once again making CANDU history.

"There has never been another project quite like this in the Canadian nuclear industry," said John Sauger, Bruce Power's Senior Vice President, Restart Project. "We're proud to be blazing a path for others to follow and I thank everyone who has brought us this far. But our work is far from over. Our job now is to put these reactors back together, to do it safely and to deliver a first-class product."

Once restarted, Units 1 and 2 will generate 1,500 megawatts of electricity, which is nearly enough to meet the average annual demand of the cities of Ottawa and Hamilton combined.

For stories and video clips on all aspects of the project, please check out our Bruce A Restart web pages at  our youtube channel at

 http://www.youtube.com/brucepower4you


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