Darlington NGS - Unit 1 Return to Service: Request for CNSC Consent to Remove Regulatory Hold Point-4, Prior To Exceeding 35 % Full Power

Regulatory Operations Branch

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

Mr. Boris Vulanovic
Senior Vice President, Refurbishment
Ontario Power Generation Inc.
1855 Energy Drive, 3C14
Courtice, ON L1E 0E7

Subject: Darlington NGS - Unit 1 Return to Service: Request for CNSC Consent to Remove Regulatory Hold Point-4, Prior To Exceeding 35 % Full Power

Dear Mr. Grace and Mr. Vulanovic:

The purpose of this letter is to respond to Ontario Power Generation’s (OPG) submission [1], which requests removal of Regulatory Hold Point-4 (RHP-4), allowing operation above 35 % full power for the refurbished Darlington Unit 1 reactor, and provides the associated Completion Assurance Document.

Canadian Nuclear Safety Commission (CNSC) 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-4. Specifically, for this RHP, CNSC staff imposed an additional requirement regarding enhanced oversight of the Return to Service (RTS) process and unit readiness to ensure that operational challenges are minimized and mitigated, resulting in a safe RTS and continued safe operation of the unit. Implementation of these additional measures was found to have been addressed to staff’s satisfaction. 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 13.04/2025, I consent to remove RHP-4 and OPG may now proceed with operation above 35 % full power for the Unit 1 reactor.

Yours sincerely,

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

c.c: A. Viktorov, A. Mathai, M. Rickard, C. Loreti, E. Delgado, A. El-Merhi, A. Oussoren, A. Josua Tanoko, C. Brown, C. Chan, C. Badal, Darlington Site Office

References:

1. OPG Letter, A. Grace and B. Vulanovic to R. Jammal, “Darlington NGS Refurbishment: Unit 1 Return to Service - Request for CNSC Consent Prior to Exceeding 35% Full Power (RHP4)”, NK38-CORR-000531-25736, November 11, 2024.
2. CNSC staff document entitled: “Request by Ontario Power Generation Inc. to Remove Regulatory Hold Point for Prior Consent Prior to Exceeding 35% Full Power (RHP4)”, Novembre 14, 2024.