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Consultation on REGDOC-2.4.4, Safety Analysis for Class IB Nuclear Facilities is now closed. Thank you to everyone who submitted comments.
REGDOC-2.4.4, Safety Analysis for Class IB Nuclear Facilities sets out requirements and guidance for applicants and licensees to demonstrate the safety of a Class IB nuclear facility, including:
This document is the first version of REGDOC‑2.4.4, Safety Analysis for Class IB Nuclear Facilities.
For additional information on safety analysis for the post-closure phase of a disposal facility, see REGDOC‑2.11.1, Waste Management, Volume III: Safety Case for Disposal of Radioactive Waste.
Consultation on REGDOC-2.4.4, Safety Analysis for Class IB Nuclear Facilities is now closed. Thank you to everyone who submitted comments.
REGDOC-2.4.4, Safety Analysis for Class IB Nuclear Facilities sets out requirements and guidance for applicants and licensees to demonstrate the safety of a Class IB nuclear facility, including:
This document is the first version of REGDOC‑2.4.4, Safety Analysis for Class IB Nuclear Facilities.
For additional information on safety analysis for the post-closure phase of a disposal facility, see REGDOC‑2.11.1, Waste Management, Volume III: Safety Case for Disposal of Radioactive Waste.
This regulatory document is part of the CNSC’s safety analysis series of regulatory documents, which also covers deterministic safety analysis, probabilistic safety assessment and nuclear criticality safety. The full list of regulatory document series is included at the end of this document and can also be found on the CNSC’s website at nuclearsafety.gc.ca/eng/acts-and-regulations/regulatory-documents
Regulatory document REGDOC-2.4.4, Safety Analysis for Class IB Nuclear Facilities sets out requirements and guidance for applicants and licensees to demonstrate the safety of a Class IB nuclear facility, including:
This document is the first version of REGDOC‑2.4.4, Safety Analysis for Class IB Nuclear Facilities.
For additional information on safety analysis for the post-closure phase of a longterm radioactive waste management facility, see REGDOC‑2.11.1, Waste Management, Volume III: Safety Case for Long-Term Radioactive Waste Management.
For information on the implementation of regulatory documents and on the graded approach, see REGDOC-3.5.3, Regulatory Fundamentals.
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The words “shall” and "must" are used to express requirements to be satisfied by the licensee or licence applicant. “Should” is used to express guidance or that which is advised. “May” is used to express an option or that which is advised or permissible within the limits of this regulatory document. “Can” is used to express possibility or capability.
Nothing contained in this document is to be construed as relieving any licensee from any other pertinent requirements. It is the licensee’s responsibility to identify and comply with all applicable regulations and licence conditions.
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This regulatory document sets out requirements and guidance for applicants and licensees to demonstrate the safety of a Class IB nuclear facility, including:
This document provides requirements and guidance for safety analysis of the following Class IB nuclear facilities:
For a deep geological repository (DGR), this regulatory document applies for the operational phase, which includes the licensed activities conducted up to the closure of the repository. Some examples of licensed activities in the operational phase include:
This document is the first version of REGDOC‑2.4.4, Safety Analysis for Class IB Nuclear Facilities.
For additional information on safety analysis for the post-closure phase of a disposal facility, see REGDOC‑2.11.1, Waste Management, Volume III: Safety Case for Disposal of Radioactive Waste [1].
Note: Given the wide range of Class IB nuclear facilities, a graded approach may be proposed by the applicant or licensee in accordance with REGDOC‑3.5.3, Regulatory Fundamentals [2].
The following provisions of the Nuclear Safety and Control Act (NSCA) and the regulations made under it are relevant to this document:
Within the CNSC’s safety and control area (SCA) framework, the safety analysis SCA covers maintenance of the safety analysis that supports the overall safety case for the facility.
Safety analysis is a systematic evaluation of the potential hazards associated with the conduct of a proposed activity or facility; it considers the effectiveness of preventive measures and strategies in reducing the effects of such hazards.
A safety analysis program is designed, developed and maintained by the applicant or licensee, and is reviewed by CNSC staff. It is documented in a safety analysis report (SAR). As stated in paragraphs 5(f) and 6(c) of the Class I Nuclear Facilities Regulations:
The SAR may reference other safety analysis documentation.
A facility’s SAR forms an important part of the licensing basis for the facility. It is used to:
develop and maintain the applicant or licensee’s policies, processes and procedures for the safe conduct of the licensed activities
The applicant or licensee should address the concept of defence in depth when developing a safety analysis for a nuclear facility.
Five levels of defence in depth are normally defined for nuclear facilities. Safety analysis plays a major role in demonstrating that levels 1 to 4 have been achieved. The applicability of safety analysis to these levels is as follows:
Level 1 The aim of the first level of defence is to prevent deviations from normal operation, and to prevent failures of structures, systems and components (SSCs) relied upon for safety.
Level 2 The aim of the second level of defence is to detect, intercept and control deviations from normal operation in order to prevent abnormal operational occurrences (AOOs) from escalating to accident conditions, and to return the facility to a state of normal operation.
Level 3 The aim of the third level of defence is to minimize the onsite consequences of accidents by providing inherent safety features, fail‑safe design, additional equipment and mitigating procedures. The most important objective for this level is to prevent releases of radioactive material and associated hazardous material or radiation levels that require offsite protective actions.
Level 4 The aim of the fourth level of defence is to mitigate the consequences of accidents that result from failure of the third level of defence in depth. The most important objective for this level is to ensure that the confinement function is maintained, thus ensuring that radioactive releases are kept as low as reasonably achievable.
Level 5 The aim of the fifth level of defence is to mitigate the radiological consequences and associated chemical consequences of releases or radiation levels that may result from accidents by means of adequately equipped emergency response facilities, emergency plans, and emergency procedures for onsite and offsite emergency response.
For more information on defence in depth, see:
The objectives of a safety analysis are to:
Requirements
The applicant or licensee shall maintain adequate capability to perform or procure safety analysis to:
The applicant or licensee shall establish a process to assess and update the safety analysis to ensure that the safety analysis reflects:
The applicant or licensee shall systematically review the safety analysis results to ensure they remain valid and continue to meet the safety goals, objectives and acceptance criteria.
The applicant or licensee shall develop, implement, conduct and maintain a safety analysis program for the nuclear facility.
In support of the program, the applicant or licensee shall establish one or more internal safety committees to advise management of the organization on safety issues related to the commissioning, operation and modification of the facility. The applicant or licensee shall ensure that the members of the committees include the necessary breadth of knowledge and experience to provide appropriate advice. The members shall, to the extent necessary, be independent of the operations management raising the safety matter. For more information, see IAEA SSR‑4, Safety of Nuclear Fuel Cycle Facilities [3].
A safety analysis program should include the following elements:
Requirements
Essential elements of a safety analysis program are the statements made by the applicant or licensee about the applicant or licensee’s safety, health and environmental policies [3]. The applicant or licensee shall provide these statements in the licence application as a declaration of the organization’s objectives and the public commitment of corporate management. To put these statements into effect, the applicant or licensee shall also specify and put in place organizational structures, standards and management arrangements capable of meeting the organization’s objectives and public commitments.
The applicant or licensee shall demonstrate that the safety analysis program is governed by the applicant or licensee’s management system and is consistent with the applicable requirements of CSA N286‑12, Management System Requirements for Nuclear Facilities [5].
Guidance
The CNSC accepts that the applicant or licensee’s safety analysis program may not map exactly onto the CNSC’s requirements and expectations for this area. However, the applicant or licensee should be able to demonstrate how all the requirements and expectations are addressed by various programs under the overall management system.
Requirements
The applicant or licensee shall perform a safety analysis for normal operation, and for internal and external events that deviate from normal operation and belong to a category of credible abnormal events [6].
2.2 Safety analysis objectives
3.1 Elements of a safety analysis program
4.1 Classification of events into facility states
4.2 Safety analysis assumptions
4.3 Postulated initiating events
4.3.1 Identification of postulated initiating events
4.3.2 Classification of postulated initiating events
4.4.1 Assessment of consequences
4.4.2 Assessment of likelihood
4.4.3 Examples of acceptable methods
4.5 Identification of structures, systems and components important to safety
4.6 Operational limits and conditions
5. Safety Analysis Documents and Records
5.1 Purpose and scope of safety analysis documents and records
5.2 Content of safety analysis documents and records
5.3 Documenting and recording postulated initiating events and design-basis accidents
5.4 Maintaining the safety analysis documents and records
6. Validation and Verification of Safety Analysis Tools
Appendix A: Sample Structure and Content for a Safety Analysis Report
Appendix B: Sample Parameters for Operational Limits and Conditions
Appendix C: Postulated Initiating Events