Instrumentation and Control Enhancements in EC6 Reactor Design

The Enhanced CANDU 6® (EC6®) is a nuclear reactor based on the proven CANDU 6 reactor that uses natural uranium and heavy water as a coolant and as a moderator. The EC6 has many enhancements to improve production and to meet next generation reactor standards. A modern distributed control system is used coupled with a new plant display system to facilitate the operation of the EC6. Computerization of safety systems is extended to include neutronic trip parameters and the Emergency Core Cooling (ECC) system. Computerized systems allow for thorough verification during their development, minimizing the installation, commissioning and maintenance times. Testing of these safety systems is also computer assisted to reduce the time required for testing and reduce the possibility of spurious trips. Enhanced safety system monitoring and equipment monitoring systems are used for early detection of faults or deterioration of equipment. This can in turn allow more targeted maintenance activities and improved safety. Critical safety parameter monitoring is also included in the design. Fission chambers are used instead of ion chambers for measuring neutron power. Fission chambers can extend the bottom of the power measurement range by three decades, allowing outages and restart of the reactor to be performed without the installation of startup instrumentation. Instrumentation is included to cater for Beyond Design Basis Accidents (BDBA). Additional battery banks are also included in the design to cater for Station Black-Out (SBO) and extended SBO. Connection provisions for mobile power generators have also been included in the design. The safety systems are controlled by modern equipment qualified to international standards for safety systems. The instrumentation required for these systems is also assessed for the severe conditions to which they might be exposed. Lessons learned from Fukushima on protection from external events are included in the design.