Performance of CANDUs: 1971-1993

Presently there are 31 Pressurized Heavy Water Reactors, based on the CANDU design, operating throughout the world. This paper reviews the lifetime performance of these CANDUs, ranging from the oldest Pickering NGS-A, RAPS and KANUPP units which went into service in the early 1970's, the newest Darlington units of which the last one reached full power in May of this year. While some units suffered from initial technical problems and others have been affected by grid limitations, in general CANDUs have been successful in achieving high capacity factors during their early years of operation. However, the pressure tube failure of Pickering 2 in August 1983 revealed the potential for a much shorter tube life than originally expected, and the resulting need for lengthy outages at mid-life to retube the reactor. To date, the pressure tube problem, and more recent steam generator problems, have resulted in reduced capability for the Ontario Hydro 'A' units. However, it is expected that the knowledge and experience gained will reduce the future impact of these problems on other reactors in the CANDU family. (author). 3 figs, 5 tabs