ML21007A340

(Vcsns), Unit 1 - License Amendment Request LAR-20-176 Update of Analytical Method to the Core Operating Limits Report with the Full Spectrum Loss of Coolant Accident Approach - Response to Request for Additional Info

ML21007A340
Person / Time
Site:	Summer
Issue date:	01/07/2021
From:	Mark D. Sartain Dominion Energy South Carolina
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML21007A339	List: ML21007A340
References
20-431
Download: ML21007A340 (12)

Text

PROPRIETARY INFORMATION-WITHHOLD UNDER 10 CFR 2.390 Dominion Energy South Carolina, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 Dominion Dominion Energy.com Energy January 7, 2021 Attn: Document Control Desk Serial No.: 20-431 U. S. Nuclear Regulatory Commission NRAMG: RO Washington, DC 20555-0001 Docket No.: 50-395 License No.: NPF-12 DOMINION ENERGY SOUTH CAROLINA, INC. {DESC)

VIRGIL C. SUMMER NUCLEAR STATION {VCSNS) UNIT 1 LICENSE AMENDMENT REQUEST LAR-20-176 "UPDATE OF ANALYTICAL METHOD TO THE CORE OPERATING LIMITS REPORT WITH THE FULL SPECTRUM LOSS OF COOLANT ACCIDENT APPROACH" RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION {RAI)

By letter dated June 4, 2020 (Agencywide Documents Access and Management System Package Accession No. ML20156A303), Dominion Energy South Carolina, Inc. (DESC),

submitted a license amendment request to revise Technical Specifications (TS) Section 6.9.1.11, "Core Operating Limits Report," for Virgil C. Summer Nuclear Station (VCSNS),

Unit 1. VCSNS is proposing to replace currently approved methods with the full spectrum loss of coolant accident analysis (FSLOCA) approach.

In an email dated December 7, 2020 from Mr. Vaughn Thomas, the VCSNS NRC Project Manager, to Mr. Yan Gao of Dominion Energy, the Nuclear Regulatory Commission (NRC) staff requested additional information to facilitate their review of the subject LAR.

The NRC's request for additional information (RAI) and DESC's responses are provided in the Enclosures to this letter. contains information proprietary to Westinghouse Electric Company, LLC

("Westinghouse"), and is supported by an Affidavit (Enclosure 3) signed by Westinghouse, the owner of the information. The Affidavit sets forth the basis on which the information may be withheld from public disclosure by the NRC and addresses with specificity the considerations listed in paragraph (b)(4) of Section 2.390 of the NRC's regulations.

Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10 CFR Section 2.390 of the NRC's regulations.

Correspondence with respect to the copyright or proprietary aspects of the information provided in the enclosures to this letter or the supporting Westinghouse Affidavit should reference CAW-20-5122 (Enclosure 3) and should be addressed to Zachary S. Harper, Manager, Licensing Engineering, Westinghouse Electric Company, 1000 Westinghouse Drive, Suite 165, Cranberry Township, Pennsylvania 16066. The non-proprietary version of the RAI responses is provided in Enclosure 2.

Enclosure 1 contains information that is being withheld from public disclosure under 1 O CFR 2.390. U pon se paration from Enclosure 1, this pga e is decontrolled.

Serial No.20-431 Docket No. 50-395 Page 2 of 3 Should you have any questions, please contact Mr. Yan Gao at (804) 273-2768.

Respectfully, Mark D. Sartain Vice President - Nuclear Engineering & Fleet Support COMMONWEAL TH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mr. Mark D. Sartain, who is Vice President - Nuclear Engineering and Fleet Support, of Dominion Energy South Carolina, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this 7+h. day of J:iuav-1 ,2021.

My Commission Expires: 1-i.! 31/J.if .

CRAIG D SLY Notary Public Notary Public Commonwealth of Virginia Reg.# 7518653 My Commission Expires December 31, 2 one

Enclosure:

Response to NRC Request for Additional Information (Proprietary) : Response to NRC Request for Additional Information (Non-Proprietary) : Westinghouse Affidavit for Withholding Proprietary Information

Serial No.20-431 Docket No. 50-395 Page 3 of 3 cc: U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, GA 30303-1257 Mr. Vaughn Thomas NRC Project Manager U.S. Nuclear Regulatory Commission Mail Stop 04 F-12 One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector V. C. Summer Nuclear Station Ms. Anuradha Nair-Gimmi Bureau of Environmental Health Services South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, SC 29201 Mr. G. J. Lindamood Santee Cooper - Nuclear Coordinator V. C. Summer Nuclear Station

Serial No.20-431 Docket No. 50-395 Enclosure 2 Response to NRC Request for Additional Information (Non-Proprietary)

Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. (DESC)

Serial No.20-431 Docket No. 50-395 Enclosure 2 - RAI Response: Page 1 of 4 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION UPDATE OF ANALYTICAL METHOD TO THE CORE OPERATING LIMITS REPORT WITH THE FULL SPECTRUM LOSS OF COOLANT ACCIDENT APPROACH DOMINION ENERGY SOUTH CAROLINA, INC. (DESC)

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 1.0 NRC REQUEST FOR ADDITIONAL INFORMATION (RAI) [2.41 Regulatory Basis The regulatory bases for the following LOCA related requests for additional information (RAls) are the requirements contained in 10 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Reactors," insofar as they establish the requirements and acceptance criteria for emergency core cooling system (ECCS) design, and for the evaluation models (EMs) used to evaluate ECCS performance during a hypothetical LOCA. Specific considerations include 10 CFR 50.46(a)(1 )(i) requires the use of an acceptable EM to evaluate ECCS performance under the conditions of a hypothetical LOCA, and 10 CFR 50.46(a)(1 )(ii) allows for the development of an EM that conforms to the required and acceptable features specified in Appendix K to 10 CFR 50. 10 CFR 50.46(a)(1)(i) also requires ECCS cooling performance to be calculated for a number of postulated LOCAs of different sizes, locations, and other properties sufficient to provide assurance that the *most severe hypothetical LOCAs are calculated.

Acceptance criteria set forth in paragraph (b) of 10 CFR 50.46, and the results of the ECCS evaluation must show that the acceptance criteria are met. Among others, these include requirements related to peak cladding temperature (PCT), maximum cladding oxidation, and maximum hydrogen generation.

Background

The licensee planned to transition from the current statistically based Best Estimate Large Break LOCA and deterministically based Small Break LOCA methods to a state-of-the-art, unified, and approved Full Spectrum LOCA approach (Reference 2). The proposed change will involve a change of VCSNS current Technical Specification 6.9.1.11, "Core Operating Limits Report," analytical methods Item (c). The proposed change in analysis methods also will fulfill the South Carolina Electric and Gas (now Dominion Energy South Carolina) commitment to address fuel pellet thermal conductivity degradation (TCD) as described in Nuclear Regulatory Commission Information Notice 2011-21, by replacing the previous PAD3.4 and PAD4.0 fuel thermal performance codes with the updated and approved PADS cod~ in the LOCA analyses.

The aforementioned Full Spectrum LOCA approach was adopted by Westinghouse to complete an analysis with the FULL SPECTRUM' loss-of-coolant accident (FSLOCA ')

evaluation model (EM) for VCSNS. This LAR requests approval to apply the Westinghouse FSLOCA EM.

Serial No.20-431 Docket No. 50-395 Enclosure 2 - RAI Response: Page 2 of 4 RAl-1; Axial Power Difference VCSNS TS LCO 3.2.1 requires the axial power difference (APO) be maintained within the allowed operational space specified in COLR as based on the Relaxed Axial Offset Control (RAOC) or within the target band specified in the COLR about the target flux difference during base load operation. Based on WCAP-16996, Figure 25.2-13, the staff has a concern that the axial power distributions created in FSLOCA EM library for VCSNS analysis may not sufficiently reflect the VCSNS reactor design. The licensee is requested to provide assurance that the axial power distributions created in FSLOCA EM library for VCSNS analysis are consistent with, or bound, those allowed by VCSNS TS LCO 3.2.1.

RAl-2; Operator Action No operator actions are described in the transient descriptions or sequences of events.

The licensee is requested to confirm that all assumed accident mitigation features occur automatically or discuss any operator actions that may be taken during the time spans as considered in the analyses.

1.1 DESCNCSNS Response RAl-1 Response The library of axial power distributions used in the VCSNS analysis with the FULL SPECTRUM' loss-of-coolant accident (FSLOCA ') evaluation model (EM) was generated using the methodology described in Section 25.2.1.4 of WCAP-16996-P-A, Revision 1 [2 .1]. [

]a,c Per Item 1.0e in Table 1 of the License Amendment Request Technical Evaluation (Attachment 4 to Agencywide Documents Access and Management System (ADAMS)

Accession No. ML20156A303 [2.2]), the VCSNS FSLOCA EM analysis supports an AFD band of -12% to +10% at 100% power. (Note that the FSLOCA EM analysis supports a wider AFD band than the most recent COLR, which allows an AFD band of -8% to 8% at 100% power per Figure 3 of ADAMS Accession No. ML20147A596 [2.3].) [

p,c Therefore, the power distributions created in FSLOCA EM library for VCSNS analysis are consistent with, or bound, those allowed by VCSNS TS LCO 3.2.1.

Serial No.20-431 Docket No. 50-395 Enclosure 2 - RAI Response: Page 3 of 4 a,c Figuni 1: [

RAl-2 Response The VCSNS FSLOCA analysis does not directly credit any operator actions. Safety system actuation occurs automatically due to the reactor trip and engineered safety feature actuation systems. In addition, the analysis does not require any new operator

Serial No.20-431 Docket No. 50-395 Enclosure 2 - RAI Response: Page 4 of 4 actions or the modification of existing operator actions in order to satisfy the applicable acceptance criteria of 10 CFR 50.46.

A continuous action step that directs operators to trip the Reactor Coolant Pumps (RCP) following a Small Break LOCA within 5 minutes of meeting a trip criterion is included in VCSNS Emergency Operating Procedures (EOPs). Additional information regarding the modeling of RCP operation within the methodological requirements of FSLOCA is contained on page B-983 of the Appendices of WCAP 16996-P-A, Revision 1 [2.1].

2.0 REFERENCES

2.1 WCAP-16996-P-A, Revision 1, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology),"

November 2016 2.2 ADAMS Accession No. ML20156A303, "Dominion Energy South Carolina (DESC),

Virgil C. Summer Nuclear Station (VCSNS) Unit 1 License Amendment Request, Update of Analytical Method to The Core Operating Limits Report with The FULL SPECTRUM Loss of Coolant Accident Approach," June 2020 2.3 ADAMS Accession No. ML20147A596, "Dominion Energy South Carolina, Inc.,

Virgil C. Summer Nuclear Station Unit 1, Core Operating Limits Report (COLR) for Cycle 26," May 2020 2.4 ADAMS Accession # ML20342A382, Request for Additional Information 2.5 Email from Mr. Vaughn Thomas (NRG) to Mr. Yan Gao (DESC) dated December 7, 2020, "Final RAI for Summer FS LOCA LAR"

Serial No.20-431 Docket No. 50-395 Enclosure 3 Westinghouse Affidavit for Withholding Proprietary Information Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. (DESC)

Serial No.20-431 Docket No. 50-395 Enclosure 3: Page 1 of 3 AFFIDAVIT (CAW-20-5122)

COMMONWEALTH OF PENNSYLVANIA:

COUNTY OF BUTLER:

(1) I, Zachary S_ Harper. have been specifically delegated and authorized to apply for withholding and execute this Affidavit on behalf of\"\lestingbouse Electric Company LLC 0.V estinghonse).

(2) I am requesting the proprietary portion,:; of CGE-20-27-P be withheld from public disclosure under 10 CFR 2-390.

(3) I have personal knowledge of the criteria and procedures utilized by Westinghouse in designating information as a trade secret, privileged, or as confidential commercial or financial information.

(4) Purniant to 10 CFR 2390, the following is .famished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld_

(i) The information sought to be withheld from public disclosure is owned and has been held in confidence by Vlestinghouse and is not customarily disclosed to the public.

(ii) The information sought to he withheld is being transmitted to the Commission in confidence and, to Westinghouse's knowledge, is not available in public sources.

(iii) Westinghouse notes that a showing of substantial harm is no longer an applicable criterion for analyzing whether a document should be withheld from public disclosure_ Nevertheless, public disclosure of this proprietary information is likely to cause substa11tial harm to the competitive position of\Vestinghouse because it would enhance the ability of competitors to provide similar technical evaluation justifications and licensing defense services for commercial power :reactors without commensurate expenses_ Also, public disclosure of1he information would enable

Serial No.20-431 Docket No. 50-395 Enclosure 3: Page 2 of 3 others to use the information to meet NRC requirements for licensing documentation without purchasing the right to use the information.

(5) \Vestinghouse has policies in place to identify proprietary information. Under that system, 111.fonnation is held in confidence if it falls i11 one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage, as follows:

(a) The information reveals the distinguishing aspects of a process (or component, strncture, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from \Vestinghouse constitutes a competitive economic advantage over other companies.

(b) It consists of supporting data, including test data, relative to a process (or component, strncture, tool, method, etc.), the application of which data secures a competitive economic advantage (e.g .. by optimization or improved marketability).

(c) Its use by a competitor would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing a similar product.

(d) It reveals cost or price information, production capacities,, budget levels, or commet"cial strategies of Westinghouse, its customers or suppliers.

(e) It reveals aspects of past, present, or foture \Vestinghouse or customer funded development plans and programs of potential commercial value to

\Vestinghouse.

(f) It contains patentable ideas, for which patent protection may be desirable.

Serial No.20-431 Docket No. 50-395 Enclosure 3: Page 3 of 3 (6) 111c attached docu1mmts are bracketed and marked to indicate the bases for withholding. The justification for withholding is indicated in both versions by 1mmns of lowcr~ca..1e letters (a) thwugh (fJ kx:ated us a superscript immediately foUowing the bracket'i cncfosing each item or infhrrnation being identified as proprfotacy or in the m.urgin opposite such information. 'lnt-sc lowcr--casc letters refcr te) tlw types of information Westinghouse customarily holds in confidence identified in s..-ctfons (S)(a) through (0 or this Affidavit, I declare that the avcrmcnts of fact set forth in this Affidavit are true and correct to the best tlfmy knowledge, infrnmation, and belief.

I declare under penalty of perjury that the foregoing is true and correct.

Licensing l~ttgineering