Inside all CANDU nuclear power reactors in Canada are several hundred fuel channels. Each one has four spacers, end fittings, a calandria tube and pressure tubes. Pressure tubes are the heart of the reactor. They are used to contain the fuel bundles and coolant During regular nuclear power plant operation, pressure tubes are exposed to high temperatures, high pressure, and intense radiation, which can cause them to deteriorate. Much like any machine, with time, parts need to be tested, serviced, and replaced. The CNSC licenses nuclear power plant operators, who are required to regularly monitor the condition of the pressure tubes, which must meet operational fitness standards. Some of the key areas to watch for in a pressure tube are subtle changes in shape, general flaws, and resistance to cracks. This is monitored through periodic testing. Engineers deliberately designed CANDU pressure tubes to withstand this operational wear and tear. Through extensive research and predictive modeling, licensees must understand the pressure tube’s ability to withstand any deterioration, and provide the CNSC with periodic inspection plans. Licensees must perform inspections and demonstrate that each pressure tube is able to continue to safely operate into the future. CNSC staff review and evaluate the data provided by the licensee to confirm that the pressure tubes meet operational standards. The CNSC, Canada’s nuclear regulator, ensures comprehensive and rigorous oversight. We will only issue a licence when we are confident that a nuclear power plant is and will remain safe to operate.