Overview of CANDU reactor safety research

There is an ongoing requirement to advance our knowledge and understanding to maintain the safety of operating reactors and to develop advanced reactor designs with enhanced features. Atomic Energy of Canada Limited (AECL) has a history of strong research programs to support the design, development and licensing basis of CANDU reactors, address specific issues raised by regulators, and support advanced product development. The licensing basis for a nuclear reactor rests primarily on its safety report, which demonstrates public safety for a number of postulated design-basis accidents in the reactor. Analysis of these accidents is performed using computer codes that solve the mathematical models representing the various accident phenomena. These codes are validated against a large number of experiments representing the phenomena for improved confidence in their predictions of the reactor behaviour. AECL follows a formal methodology established by the Canadian nuclear industry in the validation of the computer codes. The codes and experiments are classified into a number of technical disciplines such as core physics, thermalhydraulics, fuel and fuel channel behaviour, moderator and containment behaviour, etc. AECL has maintained strong code development and experimental programs in these areas in cooperation with the Canadian CANDU utilities. As a result, AECL has a well-validated computer code suite to support the CANDU reactor design and analysis. Ongoing safety research is focused on obtaining a better understanding of component aging effects and phenomena involved in severe accidents beyond the design basis. Additionally, new safety concepts in support of advanced product design are under study. In this paper, will briefly describe AECL's safety research in key technical areas, computer code development and qualification, and efforts to continue to advance the CANDU design to enhance safety. (authors)