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Letter to Ontario Power Generation regarding Regulatory Hold Point 2 – Darlington Unit 3

Regulatory Operations Branch

Sent by email only

May 20, 2023

Mr. Richard Geofroy
Senior Vice President, Nuclear
Ontario Power Generation Inc.
1 Holt Road South, P.O. Box 4000
Bowmanville, ON L1C 3Z8

Ms. Subo Sinnathamby
Senior Vice President, Refurbishment
Ontario Power Generation Inc.
1855 Energy Drive, 3C14
Courtice, ON L1E 0E7

SUBJECT: Darlington NGS - Unit 3 Return to Service: Request for CNSC Consent to Remove the Regulatory Hold Point for Prior To Removal of Guaranteed Shutdown State

Dear Mr. Geofroy and Ms. Sinnathamby:

The purpose of this letter is to respond to Ontario Power Generation’s (OPG) submission [1], which requests removal of Regulatory Hold Point-2 (RHP-2), allowing the Guaranteed Shutdown State to be removed in the refurbished Darlington Unit 3 reactor.

Canadian Nuclear Safety Commission staff’s assessment [2] of OPG’s submission [1], as well as all supporting documentation, concluded that OPG has met all the pre-requisites established by the Commission to remove RHP-2. Therefore, as the person authorized by the Commission and pursuant to Licence Condition 15.4 of the Darlington Nuclear Generating Station Power Reactor Operating Licence 13.03/2025, I consent to remove RHP-2 and OPG may now proceed with surrendering GSS to restart the refurbished reactor at low power for testing and verification.

Yours sincerely,

Ramzi Jammal
Executive Vice-President and
Chief Regulatory Operations Officer
Regulatory Operations Branch

c.c: A. Viktorov, J. Burta, A. Mathai, M. Rickard, C. Loreti, N. Abonasara, A. Oussoren, C. Badal, C. Brown, C. Chan, Darlington Site Office


  1. OPG Letter, R. Geofroy and S. Sinnathamby to R. Jammal, “Darlington NGS Refurbishment – Unit 3 Return to Service: Request for CNSC Consent Prior to Guaranteed Shutdown State (GSS) Removal (RHP 2)”, May 16, 2023.
  2. CNSC staff document entitled: “Request by Ontario Power Generation Inc. to Remove Regulatory Hold Point for Prior to Guaranteed Shutdown State for Unit 3”, May 19, 2023.
  3. CNSC Letter, J. Burta to S. Gregoris and S. Sinnathamby, “Ontario Power Generation Protocol with the Canadian Nuclear Safety Commission for Darlington Nuclear Generating Station Unit 3 Return to Service-Revision 2”, April 5, 2023.

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