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Addressing Severe Accidents Through Design Extension Conditions and Severe Accident Management

Abstract of the technical presentation presented at:
The 2018 International Severe Accident Management Conference (ISAMC-2018) and
the 7th International Workshop on CANDU Safety Association for Sustainability (CANSAS-2018)
October 15–18, 2018

Prepared by:
Noreddine Mesmous
Canadian Nuclear Safety Commission


This technical presentation summarizes Canadian Nuclear Safety Commission (CNSC) requirements and guidance on design extension conditions (DEC) and severe accident management (SAM).

The presentation is based on the following CNSC regulatory documents:

  • REGDOC-2.5.2, Design of Reactor Facilities: Nuclear Power Plants, May 2014
  • REGDOC-2.3.2, Accident Management, Version 2, September 2015
  • REGDOC-2.4.1, Deterministic Safety Analysis, May 2014

CNSC REGDOC-2.5.2, Design of Reactor Facilities: Nuclear Power Plants, requires that the design be such that plant states that could lead to significant radioactive releases are practically eliminated. Practical elimination recognizes that the possibility of certain conditions or accidents is either physically impossible or judged with a high level of confidence to be extremely unlikely.

CNSC REGDOC-2.3.2, Accident Management, Version 2 sets the requirements and guidance for accident management, including severe accident management (SAM).

CNSC REGDOC-2.4.1, Deterministic Safety Analysis, requires that a safety assessment for beyond-design-basis accidents (BDBAs) be performed to demonstrate that the nuclear power plant as designed can meet the requirements for release limits established as the safety goals.

In summary, CNSC regulatory requirements ensure that the aspects and provisions applicable to DEC and SAM implementation are adequately addressed. CNSC review and evaluation of licensees’ SAM programs is an important activity for verifying compliance with the requirements.

Key words: Accident management, severe accidents, design extension conditions

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