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Company fined after worker injured while removing bore plug on rotor


A worker suffered critical injuries while performing maintenance on a generator at a Tiverton Ontario power plant.

On February 1, 2016, Bruce Power Inc. commenced maintenance work on a rotor. A hole was drilled in the plant’s No. 8 Generator in order to remove a bore plug on the rotor. As workers were drilling the first hole, flames emanated from the drilled hole and injured a worker.

A Ministry of Labour investigation found that the flames resulted from the release of hydrogen from pressurized containment inside the rotor core. The generator uses hydrogen gas as a cooling medium and a mixture of hydrogen and air was created as the compressed hydrogen escaped through the freshly-drilled hole. The mixture of hydrogen and air was within the flammable range for hydrogen and came into contact with mulitiple ignition sources capable of igniting the mixture, such as the motor of the drill or a work light. This resulted in the flames that emanated from the drilled hole.

GE, the manufacturer of the generator, had prepared and made available a technical information letter which discussed the potential hazards associated with trapped hydrogen gas. It had recommended that the rotor core be tested and purged of hydrogen, not pressurized before plug removal, and the removal of potential sources of ignition.

This  information was not known to the team involved in the work, including  the injured worker, and its recommended method was not followed.

The court found on December 6, 2017 that Bruce Power Inc. failed as an employer to acquaint a worker with any hazard in the work and in the handling, storage, use, disposal and transport of any article, device, equipment or a biological, chemical or physical agent at a workplace located at 177 Tie Road, Tiverton, Ont., contrary to section 25(2)(d) of the Occupational Health and Safety Act.

The company was fined $110,000 by Justice of the Peace Michael A. Cuthbertson in Owen Sound court; Crown Counsel Daniel Kleiman.

Source: Ontarion Ministry of Labour