ML19217A143

Revised Response to Request for Additional Information Regarding the Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors

ML19217A143
Person / Time
Site:	Calvert Cliffs
Issue date:	08/05/2019
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML19217A143 (3)

Text

Exelon Generation 200 Exelon Way Kennett Square. PA 19348 www.exeloncorp.com 10 CFR 50.90 10 CFR 50.69 August 5, 2019 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 Docket Nos. 50-317 and 50-318 Revised Response to Request for Additional Information Regarding the Application to Adopt 1 O CFR 50.69, "Risk-Informed Categorization And Treatment of Structures, Systems, and Components for Nuclear Power Reactors," letter dated July 19, 2019

References:

1)

License Amendment Request dated November 28, 2018 titled "Application to Adopt 1 O CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors"

2)

Supplement to Application to Adopt 1 O CFR 50.69, "Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors," dated November 29, 2018

3)

Revised submittal to Application to Adopt 1 O VFR 50.69, "Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors," dated May 10, 2019

4)

E-mail from Michael Marshall, U.S. Nuclear Regulatory Commission, to Enrique Villar, Exelon, titled "[External] Calvert Cliffs Nuclear Power Plant, Units 1 And 2 - Request For Additional Information Regarding Request To Adopt 1 O CFR 50.69 Risk Informed Categorization And Treatment Of Systems, Structures, And Components (EPID L-2018-LIA-0482)," dated June 4, 2019 (ML19155A127)

5)

Response to Request for Additional Information Regarding the Application to Adopt 1 O CFR 50.69, "Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors," dated July 1, 2019

Revised Response to Request for Additional Information Regarding the Application to Adopt 1 O CFR 50.69 August 5, 2019 Page2

6)

Response to Request for Additional Information Regarding the Application to Adopt 1 O CFR 50.69, "Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors," dated July 19, 2019 By letter dated November 28, 2018 (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML18333A022), as supplemented by letters dated November 29, 2018 and May 10, 2019 (ADAMS Accession Nos. ML18337A038 and ML19130A180, respectively), Exelon Generation Company, LLC (Exelon) submitted a license amendment request (LAR) regarding Calvert Cliffs Nuclear Power Plant Units 1 and 2 (CCNPP). The proposed amendment would modify the licensing basis to allow for the implementation of the provisions of Title 10 of the Code of Federal Regulations (10 CFR)

Part 50.69, "Risk-Informed Categorization and Treatment of Structures, Systems, and Components (SSCs) for Nuclear Power Reactors."

In Reference 4, the NRC staff identified the need for additional information to complete their evaluation. The NRC's request for additional information (RAI) transmitted in Reference 4 requested 30-day responses to RAls 4, 5, 6, and 8, and 45-day responses for RAls 1, 2, 3, and 7.

By letters dated July 1, and July 19, 2019 (Reference 5 and 6), Exelon submitted its 30-day and 45-day responses.

This letter provides a revised response to RAI 3c.iv for Plant A as documented in Reference

6. Specifically, the following paragraph is deleted from the response:

"For clarification, building failures were not mapped to every SSC housed within them. Mapping building failures directly to every SSC housed within them would result in creating an overly large and detailed fault tree model that would impact the feasibility to quantify the SPRA model in a practical manner. Instead, surrogate SSC basic events were chosen to map building failures on a train or system level (e.g., basic events for 'pump fails to run' or 'CCF of pumps to run')."

Accordingly, the new response to RAI 3c.iv will read:

"Plant A did not map any building failures since none of the building failures at Plant A met the criteria for HSS."

There are no regulatory commitments contained in this letter.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 5th day of August 2019.

Revised Response to Request for Additional Information Regarding the Application to Adopt 10 CFR 50.69 August 5, 2019 Page3 If you should have any questions regarding this submittal, please contact Enrique Villar at 610-765-5736.

Respectfully, J~1. ~Jr'- &---

James Barstow Director, Licensing Exelon Generation Company, LLC cc:

Regional Administrator, NRG Region I NRG Senior Resident Inspector NRG Project Manager D. A. Tancabel, State of Maryland