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Use of a Graded Approach in the Regulation of Research Reactors at the Canadian Nuclear Safety Commission

Abstract of the technical presentation delivered at:
IAEA Technical Meeting on the Use of a Graded Approach in the Application of the Safety Requirements for Research Reactors
May 23–27, 2016

Prepared by:
Janusz E Kowalski and N. Mesmous
Canadian Nuclear Safety Commission


Safety assessments for research reactors need to be undertaken to evaluate compliance with safety requirements, and to determine the measures to ensure reactor safety. Considering the different types of research reactors and their associated use, safety assessments should be commensurate with the potential hazard, ensuring that the operation of each reactor leads to adequate safety and defence in depth.

The Canadian Nuclear Safety Commission (CNSC) has developed a regulatory framework for licensing small reactor facilities, including research reactors, that sets out requirements for the safety analysis and reactor design. Risk is a primary consideration in determining the grading of the application of regulatory requirements. The graded approach introduced in REGDOC-2.4.1 allows safety requirements to be implemented in such a way that the level of safety assessment is proportional to the potential hazard associated with the research reactor without adversely affecting safety. Grading may be applied to all components of a safety assessment, including safety analysis. In safety analysis, the scope of the analysis, identification of the postulated initiating events (PIEs) to be analyzed, complexity of safety analysis, analysis documentation and review and updates can be graded.

The scope of presentation will cover the following topics:

  • Canadian regulatory framework for licensing research reactors
  • the basis for a graded approach
  • specific aspects in application graded approach
  • the use of graded approach to safety assessments for research reactors (examples)

To obtain a copy of the abstract’s document, please contact us at or call 613.995.5894 or 1.800.668.5284 (in Canada). When contacting us, please provide the title and date of the abstract.

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