ML24087A226

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License Amendment Request - Inverter Allowed Outage Time Extension Response to Request for Additional Information
ML24087A226
Person / Time
Site: Summer 
Issue date: 03/26/2024
From: James Holloway
Dominion Energy South Carolina
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
24-122
Download: ML24087A226 (1)
v • d • e


Text

Dominion Energy South Carolina. Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 Dominion Energy.com Attn: Document Control Desk March 26, 2024 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 DOMINION ENERGY SOUTH CAROLINA (DESC)

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1

~

....@ ? Dominion tJ? Energy Serial No.:

NRAMG:

Docket No.:

License No.:

24-122 RO 50-395 NPF-12 LICENSE AMENDMENT REQUEST - INVERTER ALLOWED OUTAGE TIME (AOT)

EXTENSION RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION {RAil By letter dated November 9, 2023 (Agencywide Document Access and Management System Package Accession No. ML239317A224), as supplemented by letter dated November 28, 2023 (ADAMS Accession No. ML23332A194), Dominion Energy South Carolina Inc. (DESC) submitted a request to modify TS 3.8.3.1 to increase the completion time associated with the 120-Volt A.C. Vital Susses In an email dated March 7, 2024, from Ed Miller, NRC Senior Project Manager, to Yan Gao of Dominion Energy, the Nuclear Regulatory Commission (NRC) staff requested additional information (RAI) to facilitate their review of the subject LAR. The NRC's RAI and the DESC responses are provided in Attachment 1 to this letter.

Should you have any questions, please contact Yan Gao at (804) 273-2768.

Respectfully, Ja~JfP--;

Vice President - Nuclear Engineering and 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 James E.

Holloway, 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 on 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 ~,-H,_ day of March

, 2024.

My Commission Expires: IZ f 31 {z 'f RAIG D SLY Notary Public onwealth of Virginia eg. #_ 7518653

Commitments made in this letter:

None.

Attachment:

1. Response to NRC Request for Additional Information cc:

U.S. Nuclear Regulatory Commission, Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. G. Edward Miller NRC Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. Zach M. Turner NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 0-08 B01A 11555 Rockville Pike Rockville, Maryland 20852-2738 NRC Senior Resident Inspector V.C. Summer Nuclear Station Mr. Nathan Gauthier Section Manager Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, SC 29201 Mr. G. J. Lindamood Santee Cooper - Nuclear Coordinator 1 Riverwood Drive Moncks Corner, SC 29461 Serial No.24-122 Docket No. 50-395 Page 2 of 2 Serial No.24-122 Docket No. 50-395 Response to NRC Request for Additional Information Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. (DESC)

TABLE OF CONTENTS Serial No.24-122 Docket No. 50-395 : Page 1 of 6

1.0 BACKGROUND

............................................................................................................... 2 2.0 NRC RAls and Responses.............................................................................................. 2

3.0 REFERENCES

................................................................................................................ 6

Serial No.24-122 Docket Nos. 50-395 : Page 2 of 6 LICENSE AMENDMENT REQUEST - INVERTER ALLOWED OUTAGE TIME (ACT)

EXTENSION - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI)

1.0 BACKGROUND

By letter dated June 9, 2023 (Agencywide Document Access and Management System Package Accession No. ML239317A224), [3.1] as supplemented by letter dated November 28, 2023 (ADAMS Accession No. ML23332A194), Dominion Energy South Carolina Inc. (DESC) submitted a request to modify TS 3.8.3.1 to increase the completion time associated with the 120-Volt A.C. Vital Busses In an email dated March 7, 2024, from Ed Miller, NRC Senior Project Manager, to Yan Gao of Dominion Energy, the Nuclear Regulatory Commission (NRC) staff requested for additional information (RAI) to facilitate their review of the subject LAR. The NRC's RAI and the DESC responses are provided in Attachment 1 to this letter.

2.0 NRC RAls and Responses

==

Description:==

"The NRG staff reviewed the proposed changes to TS 3.8.3. 1. "Onsite Power Distribution

- Operating." and noticed the proposed formatting of requirements appears inconsistent with the Summer TSs. Please provide iustification for or resolve the following items:

a.

The LAR does not propose to add the term "OPERABLE" to the description of LCO 3.8.3.1, while the proposed change introduces "OPERABLE" and "inoperable" in the associated action statements.

b.

The proposed change to TS 3.8.3.1 action c would introduce the terms "INOPERABLE" and "OPERABLE" to the requirements under LCO 3.8.3.1.

The use of terms with a/I-capital letters typically indicates they are defined in TS 1. 0, "Definitions." However, "INOPERABLE" is not found in TS 1. 0.

c.

The proposed change to TS 3. 8. 3. 1 action c would describe the condition where the LCO is not met as "With one of A. C. Vital Bus Inverters #5901. 5902, 5903, or 5904 INOPERABLE... " However. these inverters are not explicitly listed in LCO 3.8.3.1: the A.G. vital busses are described as energized from "an associated inverter." (Additionally, the revised clean TS page provided in the LAR does not match the changes in the proposed TS markup page.)."

Response

DESC agrees with the RAI, items a, b, and c. Proposed changes to the LAR are provided as follows:

Note: RAI texts are italic and underlined

Changes to the LAR cover letter:

Serial No.24-122 Docket No. 50-395 : Page 3 of 6 Delete "simplify the TS Action C statement and" in the 2nd paragraph.

Delete "Attachment 4 provides the proposed TS Bases change." in the 3rd paragraph.

Delete "Attachment 4", "Proposed TS Bases Change", on page 2 of 3.

Changes to section 1.0, "

SUMMARY

DESCRIPTION", of LAR Attachment 1 Delete "simplify the existing Action C wording and" in the 1st paragraph on page 2 of

29.

Changes to section 2.3, "Reason for the Proposed Change", of LAR Delete "The nomenclature of this TS reflects the original plant design where each Vital A.C. Buss utilized a manually interlocked bypass breaker as part of the distribution panel that allowed either the Alternate A.C. power source OR the associated two (2) input inverters to energize the panel. Current plant design, which was changed in 1991 via VCSNS design modification (MRF21432), has a single input to each Vital A.C. Bus via the three source Inverter (UPS) output. As such, updating the TS wording to match the plant design more closely, and the treatment of Vital A.C. Bus energization issues as related to the OPERABIL TY of the inverter will allow more clarity and flexibility for plant personnel when utilizing TS LCO 3.8.3.1 Action statements." in the 1st paragraph on page 8 of 29.

Changes to section 2.4, "Description of the Proposed Change", of LAR Delete "and the associated TS Bases." in the 1st paragraph on page 11 of 29.

Under the title "Proposed TS LCO 3.8.3.1, Action C will state:", all the current paragraphs (on pages 11 of 29 and 12 of 29) will be deleted and replaced with: (The only change to the current TS 3.8.3.1 is to change "24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />" to "7 days.")

c.

With one of A. C. vital Busses #5901. 5902. 5903. or 5904 either not energized from its associated inverter. or with the inverter not connected to its associated D. C. Bus re-energize the A. C. vital Bus from its associated inverter connected to its associated D. C. Bus within 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Changes to Attachment 2, "CURRENT VCSNS TS PAGE MARK-UP" The new mark-up is provided below:

ELECTRICAL POWER SYSTEMS 3/4.8.3 ONSITE POWER DISTRIBUT,jQN OPERATING LIMITING CONDITION FOR OPERATION Serial No.24-122 Docket No. 50-395 : Page 4 of 6 3.8.3.1 The following electrical busses shall be energized in the specified manner with tie breakers open between redundant busses:

a.

Train A A.C. Emergency Susses consisting ot

1.

7200 volt Emergency Susses # 1DA and 1EA.

2.

480 volt Emergency Busses # 1 DA 1, 1 DA2 and 1 EA 1.

b.

Train B A.C. Emergency Susses consisting ot

1.

7200 volt Emergency Busses # 1 DB and 1 EB.

2.

480 volt Emergency Busses # 1081, 1DB2, and 1EB1.

c.

120 volt A.G. Vital Busses # 5902 and 5901 energiZed from an associated inverter connected to D.C. Bus# 1HA*.

d.

120 volt A.G. Vital Busses # 5904 and 5903 energized from an associated inverter connected to D.C. Bus# 1 HB*.

e.

120 volt A.C. Vital Bus #5907 energized.

f.

120 volt A.C. Vital Bus #5908 energized.

g.

125 volt D.C. Bus 1HA energized from Battery Bank #1A.

h.

125 volt D.C. Bus 1HB energized from Battery Bank #1 B.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTION:

a.

With one of the required trains of A.C. Emergency busses not fully energized, re-energize the division within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

b.

With one A.C. Vital Bus not energized, re-energize the A.C. Vital Bus within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

c.

With one of A.C. Vital Busses #5901, 5902, 5903, or 5904 either not energized from its associated inverter, or with the inverter not connected to its associated D.C. Bus

~

nergize the A.C. Vital Bus from its associated inverter connected to its associated D.C. Bus within 24 hgyr:s 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

  • The inverters may be disconnected from their D.C. Bus for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as necessary for the purpose of performing an equalizing charge on their associated battery bank provided (1) their vital busses are energized, and (2) the vitaJ busses associated with the other battery bank are energized from their associated inverters and connected to their associated D.C. Bus.

SUMMER - UNIT 1 3/4 8-13

Serial No.24-122 Docket No. 50-395 : Page 5 of 6 Changes to Attachment 3, " REVISED (CLEAN) VCSNS TS PAGE" The new clean page is provided below:

ELECTRICAL POWER SYSTEMS 3/4.8.3 ONSITE POWER DISTRIBUTION OPERATING LIMITING CONDITION FOR OPERATION 3.8.3.1 The following electrical busses shall be energized in the specified manner with tie breakers open between redundant busses:

a.

Train A A.C. Emergency Busses consisting of:

1.

7200 volt Emergency Busses # 1 DA and 1 EA.

2.

480 volt Emergency Busses # 10A1, 1DA2 and 1EA1.

b.

Train B A.C. Emergency Busses consisting of:

1.

7200 volt Emergency Buss es # 1 DB and 1 EB.

2.

480 volt Emergency Susses # 1 DB 1, 1082, and 1 EB1.

c.

120 volt A.C. Vital Susses# 5902 and 5901 energized from an associated inverter connected to D.C. Bus # 1HN.

d.

120 volt AC. Vital Busses # 5904 and 5903 energized from an associated inverter connected to D.C. Bus# 1 HB*.

e.

120 volt AC. Vital Bus #5907 energized.

f.

120 volt A.C. Vital Bus #5908 energized.

g_

125 volt D.C. Bus 1HA energiZed from Battery Bank #1A.

h.

125 volt D.C. Bus 1HB energized from Battery Bank #18.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTION:

a.

With one of the required trains of A.C. Emergency busses not fully energized, re-energiZe the division within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUIDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

b.

With one AC. Vital Bus not energized, re-energiz.e the A.C. Vital Bus within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

c.

With one of A.C. Vital Susses #5901, 5902, 5903, or 5904 either not energized from its associated inverter, or with the inverter not connected to its associated D.C. Bus re-energize the A.C. Vital Bus from its associated inverter connected to its associated D.C. Bus within 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

  • The inverters may be disconnected from their D.C. Bus for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as necessary for the purpose of performing an equalizing charge on their associated battery bank provided (1) their vital busses are energized, and (2) the vital busses associated with the other battery bank are energized from their associated inverters and connected to their associated D.C. Bus.

SUMMER - UNIT 1 3/4 8-13

Serial No.24-122 Docket No. 50-395 : Page 6 of 6 Changes to Attachment 4, "PROPOSED TS BASES CHANGE" Delete Attachment 4.

3.0 REFERENCES

3.1 ADAMS Accession No. ML239317A224, "Dominion Energy South Carolina (DESC)

Virgil C. Summer Nuclear Station (VCSNS) Unit 1 License Amendment Request -

Inverter Allowed Outage Time (AOT) Extension," November 9, 2023 3.2 ADAMS Accession No. ML23332A194, "Dominion Energy South Carolina (DESC)

Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Correction of Typographical Error in License Amendment Request - Inverter Allowed Outage Time (AOT) Extension,"

November 28, 2023 3.3 Email from Ed Miller (NRG) to Yan Gao (Dominion Energy) regarding RAI for VCSNS inverter LAR, March 7, 2024

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