Aging management and reliability of CANDU® steam generators and heat exchangers

The steam generators in the CANDU® and pressurized water reactor (PWR) plants are large heat exchangers that use the heat from the primary reactor coolant to make steam in the secondary side to drive steam turbine generators. The steam generators are shell-and-tube heat exchangers each with several thousands of tubes. The primary reactor coolant passes through the tubes and boils water on the outside of the tubes (secondary side) to make steam. The CANDU® design confines radioactivity from neutron activation or fission products to the primary coolant during normal operation of Calandria. CANDU® is a registered trade mark of Atomic Energy of Canada Limited. Age related degradation effects in safety related systems of CANDU® and other nuclear power plants should be managed to prevent safety margins from corrosion and eroding below the acceptable limits provided in plant design basis. In aging management and reliability of steam generators and heat exchangers just like analogous situation for Primary Heat Transport System and Feeders, an effective in-service surveillance is the essential aspect for ensuring the long-term safety and reliability of nuclear power plants (NPPs). This in-service inspection is performed in compliance with CAN-CSA-N285.4, Canadian standard for periodic inspection of CANDU® NPP components. This literature survey presents the methodology towards aging management and reliability of steam generators and heat exchangers of CANDU® Power Plants.