ML21007A323

License Amendment Request LAR-20-142 Request for Technical Specification Change Technical Specification 3.6.4, Containment Isolation Valves Response to Request for Additional Information (RAI)

ML21007A323
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
References
20-430
Download: ML21007A323 (10)

Text

Dominion Energy South Carolina, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 Dominion DominionEnergy.com Energy January 7, 2021 Attn: Document Control Desk Serial No.: 20-430 U.S. Nuclear Regulatory Commission NRA/VG: 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-20-142 REQUEST FOR TECHNICAL SPECIFICATION CHANGE TECHNICAL SPECIFICATION 3.6.4, "CONTAINMENT ISOLATION VALVES" RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI)

By letter dated April 30, 2020 (Agencywide Documents Access and Management System Accession No. ML20121A185), Dominion Energy South Carolina, Inc., (DESC) submitted a license amendment request (LAA) to modify Technical Specifications related to the containment isolation valves for Virgil C. Summer. Nuclear Station (VCSNS), Unit No. 1.

Specifically, the LAA requested a revision to the action statements associated with Technical Specification (TS) Limiting Condition for Operation (LCO) 3.6.4, ucontainment Isolation Valves," to replace the term "valve" with the term "barrier to encompass all components providing the containment isolation function and specify that actions to address an inoperable containment isolation valve apply to the affected penetration flow path only, rather than all flow paths associated with the penetration.

In an email dated December 7, 2020 from Mr. Vaughn Thomas, the VCSNS NRC Project Manager, to Mr. Yan Gao of Dominion Energy, the NRC staff requested additional information to facilitate their review of the subject LAA. The NRC's request for additional information (RAI) and the DESC's response are provided in the Enclosure to this letter.

Serial No.20-430 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 COMMONWEALTH 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-rh day of J:'t:M\U.D.~i ,2021.

My Commission Expires: 1l{ 31 / ;J. <f CRAIG D SLY Notary Public Commonwealth of Virginia Reg.#7518653 q My Commission Expires December 31, 2tr_

Commitments contained in this letter: None

Enclosure:

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, 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

Serial No.20-430 Docket No. 50-395 Page 3 of 3 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.20-430 Docket No. 50-395 Enclosure Response to NRC Request for Additional Information Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Dominion Energy South Carolina, Inc. (DESC)

Serial No.20-430 Docket No. 50-395 Enclosure - RAI Response: Page 1 of 6 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR TECHNICAL SPECIFICATION CHANGE TECHNICAL SPECIFICATION 3.6.4, "CONTAINMENT ISOLATION VALVES" DOMINION ENERGY SOUTH CAROLINA, Inc. (DESC)

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 1.0 NRC REQUEST FOR ADDITIONAL INFORMATION (RAI) [6.21

Background

By letter dated April 30, 2020 (Agencywide Documents Access and Management System Accession No. ML20121A185), Dominion Energy South Carolina, Inc., (Dominion) submitted a license amendment request to modify Technical Specifications related to the containment isolation valves for Virgil C. Summer Nuclear Station (VCSNS), Unit No. 1.

Specifically, the licensee proposed to revise the action statements associated with Technical Specification (TS) Limiting Condition for Operation (LCO) 3.6.4, "Containment Isolation Valves," to replace the term "valve" with the term "barrier" to encompass all components providing the containment isolation function and specify that actions to address an inoperable containment isolation valve apply to the affected penetration flow path only rather than all flow paths associated with the penetration.

Title 10, "Energy," of the Code of Federal Regulations (10 CFR), Section 50.36(b) states, in part: "The technical specifications will be derived from the analyses and evaluation included in the safety analysis report, and amendments thereto, submitted pursuant to 10 CFR 50.34." As stated in 10 CFR 50.34, "Contents of Applications; Technical Information," the General Design Criteria (GDC) of Appendix A to 10 CFR Part 50 establishes minimum requirements for the principal design criteria for water-cooled nuclear power plants similar in design to plants for which construction permits have previously been issued by the Commission. Pursuant to 10 CFR 50.34, the facility safety analysis report includes a description of the relation of the design bases to the principal design criteria.

Section 6.2.4 of the VCSNS UFSAR addresses conformance with the General Design Criteria (GDC) of Appendix A to 10 CFR Part 50 related to containment isolation as follows:

The design of isolation barriers for lines penetrating the Reactor Building follows the requirements of General Design Criteria 54 through 57 of 10CFR50, Appendix A.

Guidance for staff review of TSs is contained in NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition,"

Section 16.0, "Technical Specifications." The Nuclear Regulatory Commission (NRC) staff has prepared standard technical specifications (STS) for each of the light-water reactor nuclear steam supply systems and associated balance-of-plant equipment systems. The guidance specifies that the staff review whether content and format of proposed TS are consistent with the applicable STS. Where TS provisions depart from

Serial No.20-430 Docket No. 50-395 Enclosure - RAI Response: Page 2 of 6 the reference TSs, the staff determines whether proposed differences are justified by uniqueness in plant design or other considerations. The applicable current STS for VCSNS are contained in NUREG-1431, "Standard Technical Specifications -

Westinghouse Plants," Revision 4.0.

RAI 1: Maintenance of One Operable Isolation Barrier Regulatory Basis:

• In accordance with 10 CFR Part 50, Appendix A, GDC 54-Piping systems penetrating containment. Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment capabilities having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

• In accordance with 10 CFR 50.36(c)(2), limiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility, and the licensee shall shutdown the reactor or follow any remedial action permitted by the technical specifications until the condition can be met.

Discussion Condition A of STS 3.6.3 in NUREG-1431 applies when one or more penetration flow paths with one containment isolation valve (CIV) inoperable and the CIV pressure boundary intact. The associated required action specifies isolation of the affected penetration flow path.

In Section 3.0, "Technical Evaluation," of the Enclosure to the license amendment request, Dominion stated:

A change is being requested to TS 3. 6. 4 to incorporate the term penetration flow path" in place of penetration". The current TS does not differentiate between

penetration" and penetration flow path". In the event a CIV is inoperable and there are multiple CIVs in the affected penetration, the current TS can be interpreted to require isolation of all valves in the affected penetration, regardless of operability.

The proposed change clarifies the station's desire to only isolate the inoperable valve in the affected flow path that is needed to maintain containment integrity.

The proposed TS 3.6.4 action with one or more containment isolation valves inoperable includes the provision to "maintain at least one isolation barrier OPERABLE in the affected penetration(s) .... " The staff interprets the intent of this provision as ensuring that no more than one CIV is inoperable in an affected penetration flow path. However, the proposal does not necessarily limit the OPERABLE isolation barrier to the affected flow path because the phrase "affected penetration flow path" was not used in the first part of the action statement and an affected penetration may connect to multiple branch lines, each with a separate isolation barrier. Thus, the proposed provision does not clearly prohibit a temporary loss of isolation function condition for a penetration connected to multiple branch lines, which is inconsistent with the corresponding STS 3.6.3 Condition A.

Serial No.20-430 Docket No. 50-395 Enclosure - RAI Response: Page 3 of 6 Request Propose a TS 3.6.4 action statement that ensures at least one OPERABLE isolation barrier would be present in each penetration flow path affected by an inoperable CIV.

1.1 DESCNCSNS Response The proposed TS 3.6.4 action with one or more containment isolation valves inoperable includes the provision to "maintain at least one isolation barrier OPERABLE in the affected penetration(s) .... ". DESC recognizes that the proposed action statement does not necessarily limit the OPERABLE isolation barrier to the affected flow path. An affected penetration may contain multiple flow paths, each with separate isolation barriers. To clarify the intent of the proposed change, DESC proposes to replace the proposed action statement as follows:

"With one or more of the isolation valve(s) inoperable, maintain at least one isolation barrier OPERABLE in each affected penetration flow path and:"

Sections 2 and 3 provide the revised TS mark-up and clean TS pages, respectively, to accurately reflect the proposed change.

In addition, for information, Section 4 presents the associated revised TS Bases mark-up page.

Serial No.20-430 Docket No. 50-395 Enclosure - RAI Response: Page 4 of 6 2.0 REVISED TS MARK-UP PAGE COHUIMMEHT SYS'l£HS 3l~.,.4 COflTAIH,N£NT ISOLATIOH.VALYa t:'° 3;,6.4 E,4.ch contaiment 1solat1on valve snall be Of!EftABLE.*

APPtJ CA!HLITV : MODES 1, 2* 3 And 4.

ACf!ON,

"'ith one or inore of' the isolation valve(s) inoper&b1e. l'IJAintain at least one 1solation ~ OPEAA8L£ in tacn tff&eted penetration that ts ci,e<<' anc1

~, .. jbarrier I flow path Restore the ino9erable valve(s)_ to OPERABLE stat~s within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

or v/*¥lov1 path I

b. Isolate each affected penttratiOl'l ~i.th1n 4 hOurs by use of at least one deactivated aut.om&t'lt valve seei._i.in_1*,.~1 -i'A.~rt,posit1on, or

~atil ~

lsolate each affected c,enetra.tion ~itntn 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> by use of at lust one elosea ma,-,al valve or blind fla"ge* or

d. 8e 1n <<t least HOT STAHOSY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> ind in COLD SHUTDOWll within the fo11owing 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

The provisions of Spteif'lation 3.0.4 dO not apply.

SUlV{lLLAH~E REOUtlEM£NTS . I 4.6.4.l Ead\ cont&inffieTlt isolation valve shl.11 be deilOftst~ated OPERA8LE prior to returning tne va.lve to service after m&intenlt\ce. re!)l.irt or replacement work is perlofflled on the valve or its usoc:1ated actuator.

controlt or po.itel" c:iJ"CUit. bY perlorinance of a c,clif'\9 test And verH'itatton of isol*tion time.

4.6.4.2 t,c:n containment 1ao1at1on valve snali be dl!IIOnstrateo OPERABLE during the toUJ SIIITOOWK or AffUEL!N.G t<<lOE AT LEAST ONCE PER LS MOHtHS 8Y:

a. Vtf'1fy1ng that on

• Phase A contaimnent iso11tion test sig._l. e.ach Ptttse A isolation valve actuates to its isolation po,ition.

b. Ver1fy1ng that on a Phase B c:onuinment isolation test signal. each Phese 8 1sol1t1on valve &tuates to its isolation posttion.

c. verifying that on a Reactor Building Purge and Exhaust isolation test signal. each Purge and Exha~lt ~11,e ac:tuates to its isolation pcsition ..

• QS?Hcl fSF 1eilR clositi vifves ffll.Y be opened on ln inunnittant t>&sis under a.dlll1nistrat1ve control.

SUMMER " UNIT 1 3/4 6-17 Amenant Ko. 110

Serial No.20-430 Docket No. 50-395 Enclosure - RAI Response: Page 5 of 6 3.0 CLEAN TS PAGE CONTAINMENT SYSTEMS 3/4.6.4CONTAINMENT ISOLATION VALVES LIMITING CONDITION FOR OPERATION 3.6.4 Each containment isolation valve shall be OPERABLE. "'

APPLICABILITY: MODES 1, 2, 3 and 4.

ACTION:

With one or more of the isolation valve(s) inoperable, maintain at least one isolation barrier OPERABLE in each affected penetration flow path and:

a. Restore the inoperable valVe{s) to OPERABLE status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, or

b. Isolate each affected penetration flow path within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> by use of at least one deactivated automatic valve secured in the isolation position, or

c. Isolate each affected penetration flow path within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> by use of at least one dosed manual valve or blind flange, or

d. 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 provisions of Specification 3.0.4 do not apply.

SURVEILLANCE REQUIREMENTS 4.6.4.1 Each containment isolation valve shall be demonstrated OPERABLE prior to returning the valve to service after maintenance, repair, or replacement work is performed on the valve or its associated actuator, control, or power circuit by performance of a cycling test and verification of isolation time.

4.6.4.2 Each containment isolation valve shall be demonstrated OPERABLE during the COLD SHUTDOWN or REFUELING MODE AT LEAST ONCE PER 18 MONTHS BY:

a. Verifying that on a Phase A containment isolation test signal, each Phase A isolation valve actuates to its isolation position.

b. Verifying that on a Phase B containment isolation test signal, each Phase B isolation valve actuates to its isolation position.

c. Verifying that on a Reactor Building Purge and Exhaust isolation test signal, each Purge and Exhaust valve actuates to its isolation position.

,. Locked or sealed closed valVes may be opened on an intermittent basis under administrative control.

SUMMER - UNIT 1 3/4 6-17 Amendment No. 11 o

Serial No.20-430 Docket No. 50-395 Enclosure - RAI Response: Page 6 of 6 4.0 REVISED TS BASES MARK-UP PAGE Insert l Ctftow paths I flow path The ,nntainw,ent isolation valves form part of the containment pressure boundary and provide a me ns for fluid penetrations- not serving accident consequence limiting systems to be provided ,vith two isolation bar iers that are dosed on a containment isolation signal. These isolation barriers are either passive or active (automat :). Manual valves, de-activated automatic valves secured in their dosed position, blind flanges, and dosed systems re considered passive isolation barriers. Automatic valves designed to dose without operator action folio\\* 1g an accident are considered active isolation barriers. Two barriers in series are provided for each penetratio1 so that no single credible failure or malfunction of an active component can result in a loss of isolation or leakage that exceeds limits assumed in the safety analyses, One of these barriers may be a closed system. An inoperable valve may be used to isolate the affected penetratiot per TS 3.6.4.b/c. if the valve is in the dosed position (i.e, failed dosed or stuck dosed) and has power remove , if so equipped.

flow path 5.0 NO SIGNIFICANT HAZARDS CONSIDERATION The proposed response to the RAI has been reviewed against the "No Significant Hazards Consideration Determination Analysis" presented in the original LAR submittal

[6.1], and it has been determined that this RAI response has no impact on the conclusions of the previous "No Significant Hazards Consideration Determination Analysis."

6.0 REFERENCES

6.1 Dominion Energy South Carolina (DESC) Virgil C. Summer Nuclear Station (VCSNS) Unit 1 License Amendment Request LAR-20-142, Request for Technical Specification Change, Technical Specification 3.6.4, "Containment Isolation Valves" (ADAMS Accession No. ML20121A185) 6.2 Request for Additional Information (ADAMS Accession No. ML20259A347) 6.3 Email from Mr. Vaughn Thomas (NRC) to Mr. Yan Gao (DESC), dated December 7, 2020, "Final RAI for Summer LAR - TS 3.6.4"