Bringing safety performance of older plants on par with advanced reactor designs International Conference on Safety Demonstration of Advanced Water Cooled Nuclear Power Plants Vienna, 6-9 June 2017 A. Viktorov, G. Frappier Canadian Nuclear Safety Commission

Canadian Nuclear Safety Commission Regulates safe development, production and use of nuclear energy and substances in Canada   Set regulatory requirements and assure compliance Base requirements and actions on the level of risk Make independent, objective and informed decisions Serve public interest 12/31/2018 nuclearsafety.gc.ca

Fast-paced world Nuclear industry is not immune to change Societal expectations Technology of safety Knowledge of phenomena and modeling capabilities Regulatory frameworks are different today from what they used to be thirty, twenty and even ten years ago In Canada, continuous improvement in safety practices is an accepted paradigm, a recognized strength of regulatory and operational practices 12/31/2018 nuclearsafety.gc.ca

Enabling basis for safety enhancements Fundamental attributes of the Canadian regulatory regime, namely, flexible regulatory framework, and periodic safety review process allow balanced implementation of safety enhancements 12/31/2018 nuclearsafety.gc.ca

Safety and Control Areas (SCA) framework A framework which allows more differentiated approach to evaluation of various types of facilities and activities planning and conduct of inspections and technical reviews undertaking regulatory research public reporting lending a structure to the regulatory framework   http://nuclearsafety.gc.ca/eng/acts-and-regulations/regulatory-documents/index.cfm 12/31/2018 nuclearsafety.gc.ca

CNSC Safety and Control Areas Management system Conventional health and safety Human performance management Environmental protection Operating performance Emergency management and fire protection Safety analysis Waste management Physical design Security Fitness for service Safeguards and non-proliferation Radiation protection Packaging and transport 12/31/2018 nuclearsafety.gc.ca

Development and implementation of regulatory requirements Formalizing regulatory expectations (and aligning them with the IAEA guidance) at a relatively fast pace several new or revised documents every year Ad-hoc, piece-wise implementation of new requirements is burdensome for both the regulator and licensees The preferred approach is to add the new requirements at the time of Periodic Safety Review (PSR) or relicensing in Canada, the nuclear power plants are relicensed at relatively short intervals – 5 or 10 years 12/31/2018 nuclearsafety.gc.ca

Periodic Safety Review Systematic approach for assessing design and operational practices against modern requirements identifying potential safety improvements intent is to bring facility in compliance with modern requirements Gaps are assessed to find practicable resolution may be either through design changes or modification of operation Not every gap against modern requirements may be bridged in a cost effective manner 12/31/2018 nuclearsafety.gc.ca

Nuclear Power Plants in Canada All of NPP are at least 24 years old All of them either have undertaken a Periodic Safety Review or are in the process of completing one Older units have gone through refurbishment Refurbishment involves replacement of components that have reached the end of their operational life (major components may include pressure tubes of a CANDU reactor, steam generators, etc) and overhaul or upgrade of other systems where justified 12/31/2018 nuclearsafety.gc.ca

Operating NPP in Canada Reactor MWe net First power Refurbishment Periodic Safety Review Pickering A1 515 1971 2005 PSR#2 in progress Pickering A4 1972 2003 Pickering B5 516 1982   Pickering B6 1983 Pickering B7 1984 Pickering B8 1986 Darlington 1 881 1990 Planned Completed Darlington 2 In progress Darlington 3 1992 Darlington 4 1993 12/31/2018 nuclearsafety.gc.ca

Operating NPP in Canada Reactor MWe net First power Refurbishment Periodic Safety Review Bruce A1 750 1977 2012 Completed Bruce A2 1976 Bruce A3 2004 Bruce A4 1978 Bruce B5 825 1984 Planned In progress Bruce B6 Bruce B7 1986 Bruce B8 1987 Point Lepreau 635 1982 12/31/2018 nuclearsafety.gc.ca

Operational experience Powerful impetus for safety is arising from operational experience Fukushima Daiichi accident in 2011, terrorist attacks in 2001 As a consequence of the latter, physical security transformed in a very substantial way Lessons arising from the Fukushima event external hazards multi-unit events challenges to spent fuel safety accident management 12/31/2018 nuclearsafety.gc.ca

Examples of design modifications Power supplies to key safety systems in case of accidents, including portable sources Capability to add coolant to plant primary and secondary circuits and the irradiated fuel bays Containment filtered venting system dedicated to design extension conditions Provision of passive hydrogen recombiners Modifications to improve seismic and fire coping capabilities Replacement of computerized systems with modern digital assets Post accident monitoring and sampling capabilities Modification of instrumentation with increased ranges and improved survivability Additional systems to monitor and protect environment 12/31/2018 nuclearsafety.gc.ca

Improved programmatic measures Formal requirements for management system safety culture assessment of human performance Incorporation of severe accident management guidelines and with emergency response Assessment of plant habitability and equipment survivability in BDBA conditions Assessments of robustness against physical and cyber security threats Focused research (support for in-vessel debris retention), etc.   Design and other measures have predominantly strengthened the fourth and fifth levels of defence in depth 12/31/2018 nuclearsafety.gc.ca

Safety impact of the improvements Results Probabilistic Safety Assessments, which take credit of some but not all of enhancements, indicate that Core Damage Frequency may be reduced by a factor from 1.8 to 5.7 Large Release Frequency may be reduced by a factor from 1.8 to 13   Risk reduction values depend on the nature of hazard (fire, seismic events, high wind, etc) as well as particular set of safety improvements   Most programmatic improvements cannot yet be reflected in PSA modeling Safety culture Training Improved procedural guidance 12/31/2018 nuclearsafety.gc.ca

Limits to safety improvements in older NPP There are economic and physical limits to the improvements for facilities that have a limited remaining operational life easier to make changes to procedural / administrative elements design modifications require more time and resources may be occasionally counterproductive, by introducing different vulnerabilities or complexities introduce new administrative and operational burden, which may lead to errors, in particular during the transitional period 12/31/2018 nuclearsafety.gc.ca

To summarize Canadian requirements and practices evolve in response to modern expectations Operating nuclear power plants implemented various physical and procedural enhancements Some of these enhancements are expected to be standard features in advanced nuclear power plants 12/31/2018 nuclearsafety.gc.ca

CNSC – Find out More About Us Thank you for your attention 12/31/2018 nuclearsafety.gc.ca