Bruce A and B: Request pursuant to Subsection 12(2) of the General Nuclear Safety and Control Regulations: Issues Relating to Measurement of Hydrogen Equivalent Concentration in Pressure Tubes

Directorate of Power Reactor Regulation

July 13, 2021

Mr. Maury Burton
Chief Regulatory Officer
Bruce Power Inc.
P.O. Box 1540, B10-4W
177 Tie Road
Tiverton, Ontario N0G 2T0

Subject: Bruce A and B: Request pursuant to Subsection 12(2) of the General Nuclear Safety and Control Regulations: Issues Relating to Measurement of Hydrogen Equivalent Concentration in Pressure Tubes

Dear Mr. Burton:

This letter is a formal request pursuant to subsection 12(2) of the General Nuclear Safety and Control Regulations. Based on information, in relation to recent analysis of pressure tube sampling, reported to the Canadian Nuclear Safety Commission (CNSC) by Bruce Power [1, 2], it appears that the currently used models may under-predict the maximum hydrogen equivalent concentration in pressure tubes of CANDU reactors.

In accordance with Licence Condition G.1 of PROL 18.01/2028 and Section G.1 of LCH-PR-18.01/2028-R002, licensed activities shall be conducted in accordance with the licensing basis. In addition, “for unapproved operation that is not in accordance with the licensing basis, the licensee shall take action as soon as practicable to return to a state consistent with the licensing basis, taking into account the risk significance of the situation.”

CNSC staff have made recent requests to Bruce Power in relation to the specific reports [3, 4].

Further to these requests, and pursuant to my authority as a person authorized by the Commission for the purposes of subsection 12(2) of the General Nuclear Safety and Control Regulations, I request that Bruce Power conduct analysis and review regarding pressure tube fitness for service, and make a report to the Commission, no later than July 30, 2021, in respect of the following actions:

1. Analyze the impact of this information on the demonstration of pressure tube fitness for service;
2. Conduct necessary tests and analysis to verify that operation of all reactors at Bruce Power remains within their licensing basis;
3. Inform CNSC of any other measures taken in response to this information; and
4. Assess the impact of this information on the plan for Unit 3 restart post-A2131 outage.

In addition, I request that Bruce Power complete the following tests and analyses in the longer term (within 6 months of receipt of this letter), and make a report to the Commission:

5. Analysis of the hydrogen uptake model validity, reflecting new information.

Please note that, in accordance with subsection 12(2) of the General Nuclear Safety and Control Regulations, Bruce Power is required to file a report with the Commission by July 19, 2021 that contains the following information:

1. confirmation that the request will or will not be carried out or will be carried out in part;
2. any action that Bruce Power has taken to carry out the request or any part of it;
3. any reasons why the request or any part of it will not be carried out;
4. any proposed alternative means to achieve the objectives of the request; and
5. any proposed alternative period within which Bruce Power proposes to carry out the request.

If you have any questions regarding this matter, please contact Agnes Robert at 613-266-1531 or at agnes.robert@cnsc-ccsn.gc.ca.

A similar letter has been sent to all CANDU reactor licensees that are subject to the requirements of the Nuclear Safety and Control Act.

Yours truly,

Alex Viktorov, Ph.D.
Director General
Directorate of Power Reactor Regulation

c.c.:      R. Jammal, P. Elder, M. Rinker, L. Sigouin, V. Tavasoli, Bruce Site Office (CNSC)
C. Mudrick, J. Scongack, G. Newman (Bruce Power)

References:

1. Bruce Power Email, J. Thompson to L. Sigouin, “REGDOC-3.1.1 B-2021-98077 DR”, July 5, 2021.
2. Bruce Power Email, J. Thompson to L. Sigouin, “REGDOC-3.1.1 B-2021-93819”, July 8, 2021.
3. CNSC Letter, L. Sigouin to M. Burton, “Bruce A and B: CNSC Review of REGDOC-3.1.1 Event Report B-2021-98077 DR on Pressure Tube Surveillance Hydrogen Equivalent Concentration Measurements on Unit Shutdown for Major Component Replacement – New Action Item 2021-07-23406”, July 8, 2021.
4. CNSC Letter, L. Sigouin to M. Burton, “Bruce A: CNSC Review of REGDOC-3.1.1 Event Report B-2021-93819 on A2131 Outage Scrape Campaign Hydrogen Equivalent Concentration Measurements – New Action Item 2021-07-23424”, July 9, 2021.