Categorization of Plant States for CANDU Reactors (Canadian Practice). Annex II

Requirement 20 of IAEA Safety Standards Series No. SSR-2/1 (Rev. 1) states: "A set of design extension conditions shall be derived on the basis of engineering judgement, deterministic assessments and probabilistic assessments for the purpose of further improving the safety of the nuclear power plant by enhancing the plant's capabilities to withstand, without unacceptable radiological consequences, accidents that are either more severe than design basis accidents or that involve additional failures." In Canada, significant efforts were made to account for the lessons learned from the Fukushima Daiichi accident. The Canadian nuclear industry updated its CANDU severe accident management guidelines to reflect operating experience and lessons learned from the Fukushima Daiichi accident, and the Canadian Standards Association (CSA) issued its Standard N290.16-16 on Requirements for BDBAs. The CNSC issued a number of regulatory documents providing requirements and guidance regarding BDBAs. For instance, the regulatory document REGDOC-2.5.2 on Design of Reactor Facilities: Nuclear Power Plants, published in 2014, represents to a large degree the CNSC's adoption of the principles set forth in SSR-2/1 (Rev. 1).