Early in the summer of 2021, Canada’s nuclear safety regulator received alarming news. Inspections had revealed that two pressure tubes from different reactors at Canada’s largest nuclear power plant, the Bruce Nuclear Generating Station, had deteriorated far more quickly than expected.
This meant the station’s operator, Bruce Power, had violated the terms of its operating licence. The revelation put the Canadian Nuclear Safety Commission in a tight spot. How were its leaders to respond?
Pressure tubes are commonly described as the heart of the CANDU reactor, Canada’s homegrown nuclear reactor design. The tubes contain uranium fuel bundles and heavy water, which serves as coolant.
Each of Canada’s 19 operating CANDU reactors – including the eight at Bruce – contains several hundred pressure tubes. They deteriorate as they age, gradually increasing their propensity to fracture. So the industry has developed elaborate systems to monitor that deterioration, and mathematical models to predict when tubes will no longer be fit for service. CNSC officials have reassured outsiders that this approach is systematic and thorough.
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