AECL Review of CANDU 6 Design in Light of the Ontario Hydro Nuclear IIPA Technical Findings

Abstract

In the spring of 1997, Ontario Hydro (OH) conducted an Independent, Integrated Performance Assessment (IIPA) to address long-standing management, process and equipment issues within the Ontario Hydro Nuclear (OHN) organization and its multi-unit CANDU stations. This review included six Safety System Functional Inspections (SSFIs)on:· Bruce A Emergency Coolant Injection System· Bruce B Service Water Systems· Darlington Compressed Air Systems· Pickering Electrical Distribution Systems· Fire Protection (Programmatic)· In-Service Environmental Qualification Program (Programmatic)Overall, the OHN inspections found that the design of the CANDU plant is robust and plant hardware (including equipment and materials), for the most part, is adequately reliable. However, the SSFIs also identified a number of deficiencies in the areas of management, control of design/engineering, operations, training, maintenance, testing and quality assurance. Atomic Energy of Canada Limited (AECL) has undertaken an in-depth review of all design-related issues to assess their applicability and impact on the current CANDU 6 design. The AECL review has determined that equipment/design and programmatic deficiencies identified at the OHN plants have been addressed in the current CANDU 6 design through an effective design feedback process and the application of modern codes and standards that were not in place during the design of the early OHN stations. Many of the design-related SSFI findings can be attributed to inadequate configuration management and the impact of unauthorized design modifications. Problems in these areas can arise at any nuclear station and prevention requires adherence to quality engineering procedures and documentation processes.