CNSC amends Ontario Power Generation’s power reactor operating licence for its Darlington Nuclear Generating Station to authorize the production of Molybdenum-99

News release

November 9, 2021 – Ottawa

The Canadian Nuclear Safety Commission (CNSC) announced today that it has amended the power reactor operating licence held by Ontario Power Generation Inc. (OPG) for its Darlington Nuclear Generating Station (NGS) in the Municipality of Clarington, Ontario. This decision follows a public hearing in writing. The amended licence authorizes OPG to produce Molybdenum-99 (Mo-99) at the Darlington NGS.

In making its decision, the Commission considered written submissions from OPG, CNSC staff, and 10 intervenors. The CNSC also made participant funding available through its Participant Funding Program, and invited interventions from Indigenous groups, members of the public and stakeholders in this matter. Five requesters received participant funding to assist with their interventions.

After reviewing all submissions, the Commission concluded that OPG is qualified to carry out the Mo-99 production activities that the amended licence will authorize. It also concluded that OPG will make adequate provision for the protection of the environment, and the health and safety of persons.

The record of decision is available on request to the Commission Secretariat at The decision will also be posted in both official languages at at a later date. All submissions are available on the CNSC website.

The CNSC regulates the use of nuclear energy and materials to protect health, safety, security and the environment; to implement Canada’s international commitments on the peaceful use of nuclear energy; and to disseminate objective scientific, technical and regulatory information to the public.


  • OPG applied for a licence amendment in December 2018, updated its application in June 2020, and submitted an application addendum in February 2021.
  • In May 2021, the CNSC made funding available through the Participant Funding Program to support Indigenous peoples, members of the public and stakeholders in presenting their views to the Commission.
  • A panel of the Commission held a hearing in writing in fall 2021 (hearing submissions are available online or on request).  
  • The amended licence is valid until November 30, 2025.

Quick facts

  • This licence amendment authorizes OPG to produce Mo-99 in Unit 2 of the Darlington NGS only.

  • OPG plans to install an isotope irradiation system (IIS) in Unit 2 to produce Mo-99, contingent on the release of two regulatory hold points related to the installation and commissioning of the Mo-99 IIS.

  • In its decision, the Commission authorized the CNSC’s Executive Vice-President and Chief Regulatory Operations Officer to release the two regulatory hold points, upon verifying that OPG has taken the prerequisite steps for their release. 

Associated links


Meghan Gerrish
Media Relations
Canadian Nuclear Safety Commission
613-996-6860 or 1-800-668-5284

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