ML24033A059

Response to Request for Additional Information License Amendment Request to Exclude the Dynamic Effects of Specific Postulated Pipe Ruptures from the Design and Licensing Basis Based on Leak-Before-Break Methodology

ML24033A059
Person / Time
Site:	Robinson
Issue date:	02/02/2024
From:	Basta L Duke Energy Progress
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RA 24-0005
Download: ML24033A059 (6)

Text

Laura A Basta

(_~ DUKE H B Robinson Steam Electric Plant Unit 2

'(; ENERGY<< Site Vice President

Duke Energy 3581 West Entrance Road Hartsvute, SC 29550 O: 843 951 1701 Lau ra.Basta@duke -energy com

10 CFR 50.4 Serial: RA 24-0005 February 2, 2024

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

H. B. Robinson Steam Electric Plant, Unit Number. 2 Docket Number 50-261 I Renewed License Number. DPR-23

SUBJECT:

Duke Energy Progress, LLC (Duke Energy)

Response to Request for Additional Information License Amendment Request to Exclude the Dynamic Effects of Specific Postulated Pipe Ruptures from the Design and Licensing Basis Based on Leak-Before-Break Methodology

REFERENCES:

1. Duke Energy Letter (RA-22-0290) dated August 30, 2023, License Amendment Request to Exclude the Dynamic Effects of Specific Postulated Pipe Ruptures from the Design and Licensing Basis Based on Leak-Before-Break Methodology (ADAMS Accession Number ML23242A086) 2. NRC Memorandum dated January 2, 2024, Request for Additional Information Regarding Duke's August 20, 2023, License Amendment Request for Robinson, Unit 2 (EPID L-2023-LLA-0122) (ADAMS Accession Number ML24002A738)

In Reference 1, Duke Energy Progress, LLC (Duke Energy) submitted a license amendment request for H. B. Robinson Steam Electric Plant, Unit Number 2 (RNP) to permit the application of leak-before-break (LBB) methodology to auxiliary piping systems attached to the Reactor Coolant System to eliminate the dynamic effects of postulated pipe ruptures. By email dated January 2, 2024 (Reference 2), Mr. Luke Haeg (RNP NRC Project Manager) provided a Request for Additional Information (RAI) to support the NRC staffs technical review of Reference 1. Attachment 1 to this submittal provides the response to the RAI.

Duke Energy has determined that the information provided in this submittal does not alter the conclusions reached in the 10 CFR 50.92 no significant hazards determination previously submitted. In addition, the information provided in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.

U.S. Nuclear Regulatory Commission RA 24-0005 Page 2

No new regulatory commitments are established by this submittal. Should you have any questions concerning this submittal, please contact Paul Guill at 980-373-5873 or by email at paul.guill@duke-energy.com.

I declare under penalty of perjury that the foregoing is true and correct. Executed on February 2, 2024.

Sincerely,

Laura A. Basta Site Vice President

Attachment:

Response to Request for Additional Information

cc: (with Attachment)

L. Dudes, Regional Administrator USNRC Region II J. Zeiler, NRC Senior Resident Inspector L. Haeg, NRR Project Manager A. Wilson, Attorney General (SC)

R. S. Mack, Assistant Bureau Chief, Bureau of Environmental Health Services (SC)

L. Garner, Manager, Radioact ive and Infectious Waste Management Section (SC )

U.S. Nuclear Regulatory Commission RA 24-0005 Page 3

bee: (with Attachment)

Kevin Ellis Ryan Treadway Tracey LeRoy Rounette Nader Greg Robison Laura Basta Phillip Mason Mark Hubbard David Pitsley Samuel Shicks File: (Corporate)

Electronic Licensing Library (ELL)

ATTACHMENT

Response to Request for Additional Information License Amendment Request to Exclude the Dynamic Effects of Specific Postulated Pipe Ruptures from the Design and Licensing Basis Based on Leak-Before-Break Methodology REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO ELIMINATE THE DYNAMIC EFFECTS OF POSTULATED PIPE RUPTURES TO AUXILIARY PIPING SYSTEMS ATTACHED TO THE REACTOR COOLANT SYSTEM FROM THE ROBINSON DESIGN ANO LICENSING BASIS USING LEAK-BEFORE-BREAK METHODOLOGY EPIO L-2023-LLA-0122 DUKE ENERGY PROGRESS, LLC H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261

INTRODUCTION By letter dated August 30, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23242A086), Duke Energy Progress, LLC (Duke Energy, the licensee), submitted a license amendment request (LAR) for H. B. Robinson Steam Electric Plant, Unit No. 2 (Robinson). The proposed amendment would eliminate the dynamic effects of postulated pipe ruptures to auxiliary piping systems attached to the Reactor Coolant System (RCS) from the Robinson design and licensing basis using Leak-Before-Break (LBB) methodology.

REGULATORY BASIS Title 1 0 of the Code of Federal Regulations ( 10 CFR) Part 50, Appendix A, General Design Criterion (GDC) 4, "Environmental and dynamic effects design bases," following the guidance of NUREG- 0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition", Section 3.6.3, "Leak-Before-Break Evaluation Procedures".

As noted in GDC 4, dynamic effects associated with postulated pipe ruptures in nuclear power units may be excluded from the design basis when analyses reviewed and approved by the Commission demonstrate the probability of fluid system piping rupture is extremely low under conditions consistent with the design basis for the piping.

RAl-1 For the LBS analysis that was performed for the Pressurizer Surge Line, the Residual Heat Removal Lines (RHR), and Accumulator Lines, clarify whether the flow momentum loss due to crack path turning (turning loss) is considered in the calculation of the leakage flaw size. If so, describe the total number of turns and turning angle for each leakage flaw discussed in the submittal and their technical basis. If it is not considered, explain why turning losses do not need to be considered. In addition, describe the crack surface roughness used in the leakage flaw size calculation and its technical basis.

RAl-1 Response For the LBS analysis that was performed for the Pressurizer Surge Line, the Residual Heat Removal Lines (RHR), and Accumulator Lines, no flow momentum loss due to crack path turning (turning loss) is considered in the calculation of the leakage flaw size. The leak rate calculations are performed considering a fatigue crack condition (with surface roughness based on Westinghouse data).

Westinghouse developed crack relative roughness values which have been previously accepted by the NRC. WCAP-9558 Revision 2 (Proprietary), "Mechanistic Fracture Evaluation of Reactor Coolant Pipe Containing a Postulated Circumferential Through-wall Crack" dated May 1981, documented the crack surface roughness that was used for the fracture mechanics LBB leak rate calculations. Since 1981 Westinghouse has applied this crack surface roughness value for all similar LBS applications. The fatigue crack surface roughness of "Y" micro-inches (Westinghouse proprietary information) is used for the leak rate calculation by Westinghouse.

WCAP-9558 Revision 2 (Proprietary) substantiated the approach and basis for the specified crack surface roughness. Westinghouse concludes that this fatigue crack surface roughness value is sufficiently conservative. Since 1981 Westinghouse has applied this crack relative roughness value and no additional path turning (turning loss) is considered for the fatigue crack surface for all LBS applications leak rate calculations.

The Westinghouse-developed methodology used in previous LBS applications, considering the surface roughness, has been independently verified by the Staff and subsequently accepted by the NRC (ADAMS Accession Number ML21175A185).

RAl-2 When the leakage and critical flaw lengths are expressed as the multiplication of the pipe radius and the angle of the flaw, clarify which radius of the pipe (e.g., inner, mean, or outer radius) is used in the calculation of the flaw lengths.

RAl-2 Response The leakage and critical flaw lengths are expressed as the multiplication of the pipe mean radius.