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Written by Richard Howes, OCH Magazine
With 85 cranes and over 750 hoists on site, the crane guys at North America’s largest nuclear power site have their work cut out.
Pete Richards, multi-trade team leader, crane crew, and Fred Wolsey, system engineer, cranes and hoists, are responsible for the safe operation and upkeep of all the lifting equipment at Bruce Power, Canada’s first private nuclear generating company and the source of more than 20% of Ontario’s electricity. The facility is located approximately 250km northwest of Toronto.
On a day in mid-May this year, Bruce Power’s Unit 5 was in a ‘shutdown’ state for regular maintenance. The unit which usually generates about 890 megawatts of electrical power had the focus of numerous workgroups. Replacing the energy supplied by such a unit is of substantial value to the company and its stakeholders.
The crane crew, which consists of a team of six electrical and eight mechanical technicians, was working elsewhere on site at the spent fuel bay at the Bruce ‘A’ station where a newly installed Canadian Overhead Handling Inc. 100 ton crane, with 80ft span, was being inspected.
This crane has a technical positioning system which allows movement of the load (highly radioactive spent fuel) only within confined coordinates. The spent fuel is encased in a shielding flask which protects the workers and environment from any external dose. It weighs close to the full capacity of the 100 ton crane.
Having completed work at the spent fuel bay, the crew found themselves in transit to the ‘B’ station, where a crane in the reactor vault had ceased to function in one direction during the ‘shutdown’ phase. The cranes at Unit 4 of the ‘B’ station have been in operation since commissioning almost 30 years ago. In the hot, highly radioactive environment, insulating material and plastics deteriorate at a higher rate than in conventional systems.
The electrical technicians of the crane crew have acquired experience and skills to enable them to expeditiously locate the “gremlins,” as the crane guys put it, which in this case invaded the control circuits of the vault crane. With this problem solved, detailed work reports and system weaknesses identified, the crew returned to the day’s original activities.
Having regular inspections by qualified and knowledgeable staff has ensured safe operation of these cranes over many years. It has become apparent, however, that in order to maximize efficiency and minimize downtime and radiation dose exposure to the crane crews, the cranes in each of the Bruce Power ‘B’ plant units will need to be replaced. Planning is now underway to begin replacement of the first unit’s cranes in the Spring 2009.
The commitment to replace the eight vault cranes (two cranes per unit), with 10.5 ton capacity Yale units with 60ft spans, has been accepted by the crane crew who will help design, build, install and commission the cranes. Ultimately, the crew will have intimate knowledge of the working of the new cranes which will help provide safe, reliable operation, crucial to the activities associated with shutdown maintenance.
The crane maintenance program at Bruce Power is recognized as an Industry Best Practice by the Electric Power Research Institute (EPRI).