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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. (next column)
05/03/2009 11:24 AM
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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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