Document History of REGDOC-2.5.4, Design of Uranium Mines and Mills: Ventilation Systems (formerly G-221)

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REGDOC-2.5.4, Design of Uranium Mines and Mills: Ventilation Systems (formerly G-221) provides guidance on addressing the requirements for submitting ventilation-related information when applying for a CNSC licence to site and construct, operate or decommission a uranium mine or mill. This regulatory document is also intended to help applicants for a uranium mine or mill licence understand their operational and maintenance obligations for ventilation systems, and to help CNSC staff evaluate the adequacy of applications for uranium mine and mill licences.

REGDOC-2.5.4 has the following updates from G-221:

  • New title
  • New cover and inside cover
  • A sentence in the Glossary pointing to REGDOC-3.6, Glossary of CNSC Terminology
  • New back page showing the CNSC regulatory document series
  • Addition of full references to the Nuclear Safety and Control Act and its regulations to section 1.3, Relevant legislation
  • Update of G-221’s section 3.2, Regulatory and licensing process, to REGDOC-2.5.4’s section 2, Environmental and licensing process:
    • References to and descriptions of the Canadian Environmental Assessment Act (CEAA) no longer apply and the section was updated to reflect the new Act (CEAA 2012)
    • CNSC point-of-contact information, as well as information on submitting a licence application, was added


March 29, 2018: Published.

Document Milestone Dates Links
Consultation October 4, 2017 to November 15, 2017

View the October 4, 2017 news release

(Draft REGDOC-2.5.4 HTML)
(Draft REGDOC-2.5.4 PDF)

Invitation to provide feedback on comments received N/A No comments received
Publication March 29, 2018 REGDOC-2.5.4

Contact information

For questions and information related to REGDOC-2.5.4, Design of Uranium Mines and Mills: Ventilation Systems (formerly G-221), please contact:

Directorate of Nuclear Cycle and Facilities Regulation

Canadian Nuclear Safety Commission
P.O. Box 1046, Station B
280 Slater Street
Ottawa, ON, Canada K1P 5S9

Telephone: 1-800-668-5284 (Canada only)
Fax: 613-995-5086

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