RC-15-0125, Fifth Six-Month Status Report in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)

Fifth Six-Month Status Report in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)

ML15239A750
Person / Time
Site:	Summer
Issue date:	08/24/2015
From:	Gatlin T SCANA Corp, South Carolina Electric & Gas Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CR-12-01078, EA-12-049, RC-15-0125
Download: ML15239A750 (32)

Text

Thomas D. Gatlin Vice President,Nuclear Operations (803) 345-4342 A scANA COMPANY August 24, 2015 RC-15-0125 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555-0001

Subject:

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS), UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 FIFTH SIX-MONTH STATUS REPORT IN RESPONSE TO MARCH 12, 2012, COMMISSION ORDER MODIFYING LICENSES WITH REGARD TO REQUIREMENTS FOR MITIGATION STRATEGIES FOR BEYOND-DESIGN-BASIS EXTERNAL EVENTS (ORDER NUMBER EA-12-049)

References:

1. Nuclear Regulatory Commission (NRC) Order Number EA-12-049, Issuance of Orderto Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, dated March 12, 2012, Agencywide Documents Access and Management System (ADAMS) Accession Number ML12054A735

2. NRC Interim Staff Guidance JLD-ISG-201 2-01, Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, Revision 0, dated August 29, 2012, ADAMS Accession Number ML12229A174

3. NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, Revision 0, dated August 2012, ADAMS Accession Number ML12242A378

4. SCE&G Letter, Virgil C. Summer Nuclear Station (VCSNS) Unit 1 Initial Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis ExternalEvents (OrderNumber EA-12-049),

dated October 17, 2012, ADAMS Accession Number ML12296A252

5. SCE&G Letter, Virgil C. Summer, Unit 1, Overall Integrated Plan as Required by March 12, 2012 Commission OrderModifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (OrderNumber EA-12-049), dated February 28, 2013, ADAMS Accession Number ML13063A150 On March 12, 2012, the Nuclear Regulatory Commission issued Order EA-12-049 (i.e., Reference 1) to South Carolina Electric & Gas Company (SCE&G). Reference 1 was immediately effective and directed SCE&G to develop, implement, and maintain guidance and R0. Box 88. Jenkinsville, Sc. 29065. F(803) 941-9776,l V.C.Summer Nuclear Station P. l] i_

Document Control Desk RC-1 5-0125 CR-I12-01078 Page 2 of 3 strategies to maintain or restore core cooling, containment, and spent fuel pool cooling capabilities in the event of a beyond-design-basis external event. Specific requirements are outlined in Attachment 2 of Reference 1.

Reference 1 required submission of an initial status report 60 days following issuance of the final interim staff guidance (i.e., Reference 2) and an Overall Integrated Plan (OIP) pursuant to Section IV, Condition C. Reference 2 endorses industry guidance document NEI 12-06, Revision 0 (i.e., Reference 3) with clarifications and exceptions identified in Reference 2.

Reference 4 provided the initial status report regarding mitigation strategies at the Virgil C.

Summer Nuclear Station (VCSNS), Unit 1. Reference 5 provided the OIP for VCSNS, Unit 1.

In addition, Reference 1 requires submission of status reports at six-month intervals following submittal of the QIP. Reference 3 provides direction regarding the content of the status reports.

The purpose of this letter is to provide the fifth six-month status report pursuant to Section IV, Condition C.2, of Reference 1, that delineates progress made in implementing the requirements of Reference 1. The enclosed report provides an update of milestone accomplishments since the last status report, including any changes to the compliance method, schedule, or need for relief and the basis, if any.

This letter contains no new regulatory commitments. If you have any questions regarding this report, please contact Bruce L. Thompson at (803) 931-5042.

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

E~ecued onThomas D. Gatlin P FITDG/ts Enclosure Virgil C. Summer Nuclear Station (VCSNS), Unit 1- Fifth Six-Month Status Report for the Implementation of Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order EA-12-049)

Document Control Desk RC- 15-O0125 CR-1 2-01078 Page 3 of 3 c: K. B. Marsh S. A. Byrne J. B. Archie N. S. Cams J. H. Hamilton J. W. Williams W. M. Cherry V. M. McCree (w/attachments)

W. M. Dean S. A. Williams (w/attachments)

M. A. Brown (w/attachments)

NRC Resident Inspector K. M. Sutton NSRC RTS (CR-01078)

File (815,.07)

PRSF (RC- 0125)

Document Control Desk Enclosure RC-1 5-0125 CR-I12-01078 Page 1 of 8 VIRGIL C. SUMMER NUCLEAR STATION, UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 ENCLOSURE FIFTH SIX-MONTH STATUS REPORT FOR THE IMPLEMENTATION OF ORDER MODIFYING LICENSES WITH REGARD TO REQUIREMENTS FOR MITIGATION STRATEGIES FOR BEYOND-DESIGN-BASIS EXTERNAL EVENTS (ORDER EA-12-049)

Document Control Desk Enclosure RC-l15-0125 CR-I12-01078 Page 2 of 8 1 Introduction South Carolina Electric & Gas Company (SCE&G) developed an Overall Integrated Plan (i.e., Reference 1 in Section 8) for Virgil C. Summer Nuclear Station (VCSNS), Unit 1, documenting the diverse and flexible strategies (FLEX), in response to Nuclear Regulatory Commission (NRC) Order EA-12-049 (i.e., Reference 2 in Section 8). Subsequently, SCE&G provided the first, second, third, and fourth six-month status reports (i.e., References 3, 4, 6, and 7 in Section 8, respectively). This report, the fifth six-month status report, provides an update of milestone accomplishments including any changes to the compliance method, schedule, or need for relief/relaxation and the basis, if any, which occurred during the period between February 17, 2015, and August 15, 2015, hereafter referred to as the "update period."

2 Milestone Accomplishments The following milestone(s) were completed during the update period:

0 Submit 6-month update Perform Staffing Analysis 0 Design Storage Building Develop Training Plan 3 Milestone Schedule Status The following provides an update to Attachment 2 of the Overall Integrated Plan. It provides the activity status of each item, and whether the expected completion date has changed. The dates are planning dates subject to change as design and implementation details are developed.

Target Revised Target Mieson Cmpeton Activity Com pletion Date SttsDate Submit 60 Day Status Report Oct 2012 Complete Submit Overall Integrated Plan Feb 2013 Complete Submit 6 Month Updates:

Update 1 Aug 2013 Complete Update 2 Feb 2014 Complete Update 3 Aug 2014 Complete Update 4 Feb 2015 Complete Update 5 Aug 2015 Complete Update 6 Feb 2016 Not Started FLEX Strategy Evaluation Aug 2013 Complete Walk-Throughs or Demonstrations Aug 2015 In Progress October 2015 Perform Staffing Analysis Jul 2014 Complete July 2015 Modifications:

Modifications Evaluation Dec 2013 Complete Unit 1 Design Engineering Evaluation Jan 2015 Complete Unit 1 Implementation Outage Nov 2015 In Progress

Document Control Desk Enclosure RC-1 5-0125 CR-i12-01078 Page 3 of 8 Target Revised Target Milestone Completion Activity Cmlto Status Datpeto Date Dt Storage:

Design Storage Building Jul 2014 Complete March 2015 Storage Implementation Jul 2015 In Progress September 2015 FLEX Equipment: ______

Procure On-Site Equipment Oct 2014 In Progress October 2015 Develop Strategies with RRC Nov 2014 Complete Install Off-Site Delivery' Station (ifAu203 Cmlt Necessary)Au203 Cmlt Procedures:

PWROG issues NSSS-specificMa203 Cmlt guidelinesMa203 Cmlt Create Site-Specific FSGs (FSPs) Feb 2014 In Progress October 2015 Create Maintenance Procedures Oct 2014 In Progress October 2015 Training:

Develop Training Plan Jan 2015 Complete March 2015 Training Complete Jul 2015 In Progress November 2015 Unit 1 FLEX Implementation Nov 2015 Not Started July 2016 Submit Completion Report Jan 2016 Not Started August 2016 4 Changes to Compliance Method The following summarizes changes that were made during this update period to the compliance method as documented in the Overall Integrated Plan (i.e., Reference 1) or to the changes that were submitted in References 3, 4, 6, or 7 of this status report. These changes do not impact VCSNS's compliance with NEI 12-06.

1. Change: The Sequence of Events (SOE) and multiple time constraints related to the SOE have been changed during this update period. Section 4 of the Overall Integrated Plan, Sequence of Events and Technical Basis, and corresponding attachment, Attachment IA, Sequence of Events Timeline, have been revised accordingly. Given that Section 4 and Attachment 1A have undergone significant changes, they are provided in their entirety within Attachment I to this update.

Justification: Section 4 and Attachment lA, of the Overall Integrated Plan, have been revised to reflect current strategies and updated information (e.g., finalized calculations, procedures, and walkthroughs).

Documentation: The SOE and the technical basis for each time constraint is being documented in VCSNS Technical Report, TR00080-006, FLEX Time Constraints Basis, (DRAFT at the time of this update).

Document Control Desk Enclosure RC-1 5-0125 CR-i12-01078 Page 4 of 8

2. Changqe: In order to maintain core cooling during Phase 2, the primary strategy is being modified to include an alternate suction source for the Emergency Feed Water (EFW) pumps in the event the minimum Condensate Storage Tank (CST) inventory is not immediately available. A FLEX Alternate EFW Suction Pump will transfer water from the Ultimate Heat Sink (UHS) to the 'C' Service Water (SW) Pump header to allow alignment to any EFW pump via the design basis SW to EFW flow path.

Justification: The CST does not meet the hazard protection requirements concerning high winds from tornados documented in NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, Revision 0. Therefore, the CST is not creditable for FLEX. This change will ensure a strategy exists to cope with all applicable beyond-design-basis external events (BDBEE).

Documentation: VCSNS Plant Modification, FLEX Feed Connections, ECR 51003B.

Note: Section 5 contains information regarding the request for schedule relaxation regarding this change.

3. Changqe: The time constraint to refill the CST, following a BDBEE, was changed to 8.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

Justification: Updates to the timeline, with respect to refilling the CST, are based on the minimum volume assumed to be available in the CST at T=0. This volume is the Technical Specification (T/S) minimum.

Documentation: The SQE and the technical basis for each time constraint is being documented in VCSNS Technical Report, TR00080-006, FLEX Time Constraints Basis, (DRAFT at the time of this update).

4. Changqe: The strategy for Reactor Coolant System (RCS) inventory and reactivity control, Phase 2, included use of the station's installed Alternate Seal Injection (ASI) pump and a portable FLEX RCS Makeup Pump (FX RCS MU PUMP). The strategy has been changed to credit two FX RCS MU PUMPS.

Justification: The additional FX RCS MU PUMP, an on-site portable diesel-driven pump, meets the requirements within NEI 12-06. The pumps will be stored in diverse locations, one in the Emergency Response Building (ERB) and one in the FLEX Storage Building (FSB). Although the ASI pump could not be credited for FLEX, if it survives the event, it will be used to provide flow to the Reactor Coolant Pump (RCP) seals.

Documentation: Flex Support Procedures reflect the availability of two FX RCS MU Pumps to support this strategy.

5. Changqe: The strategy for RCS inventory and reactivity control, Phase 3, has been modified to include a mobile boration skid. The skid will be provided by the National SAFER Response Center (NSRC).

Document Control Desk Enclosure RC-1 5-0125 CR-12-01 078 Page 5 of 8 Justification: The NSRC mobile boration skid will be available, as needed, to provide long term boration needs.

Documentation: The SAFER Response Plan includes use of the mobile boration skid.

6. Change: An offsite staging area, located at the SCANA Corporate Campus in Cayce, SC, was added to the SAFER Response Plan for VCSNS.

Justification: The interim staging area will be utilized if overland routes, from the Columbia Metropolitan Airport (CAE) to VCSNS, are not available following an event. In this case, equipment will be delivered by truck from CAE to the SCANA Corporate Campus. The equipment will then be delivered to the site by helicopter. This staging area was chosen so that the helicopter company could gain Federal Aviation Administration approval of the congested area flight plan.

Documentation: The SAFER Response Plan identifies the additional staging area.

7. Chanqe: Two methods for extending DC power availability, Phase 2, are being added to the Safety Function Support strategies. These methods will utilize B5b equipment. One method uses a portable 80kW generator and AC distribution panel to supply AC power to the input of the Station Battery Chargers. The second method uses a portable 80kW generator and a portable battery charger to supply DC power to the output of the station battery chargers. The equipment for one method will be stored in the ERB and the equipment for the other method will be stored in the FSB.

Justification: The ability to provide alternate power to the Station Batteries using B5b equipment provides defense in depth.

Documentation: A Flex Support Procedure reflects the availability of B5b equipment to support this strategy.

8. Changqe: The following figures have been revised to reflect current strategies. The updated figures are provided within Attachment 2 of this report.

Figure 4 - Conceptual Strategy for Reactor Makeup and Reactivity Control Figure 5 - Conceptual Coping Strategies for Support Functions from EB Figure 7 - Conceptual Strategy for Supplying SG Makeup Using Alternate EFW Suction Figure 8 - Conceptual FLEX Feed Hose Layout Figure 11 - FLEX Strategy Conceptual Mechanical Diagram Figure 12 - FLEX Strategy Conceptual Electrical Diagram Figure 14 - FLEX Storage and Deployment Site Plan

Document Control Desk Enclosure RC-15-0 125 CR-I12-01078 Page 6 of 8 5 Need for Relief/Relaxation and Basis for the Relief/Relaxation SCE&G expects to be in full compliance with NRC Order EA-12-049 by the end of the upcoming outage (start date of October 3, 2015) with the exception of the core cooling mitigation strategy.

The station recently determined that the CST, which was credited for providing EFW for core cooling, does not meet the hazard protection requirements regarding high winds from tornados outlined in NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, Revision 0, without physical modification to the tank or surrounding structures. VCSNS is currently pursuing an alternate emergency feedwater suction strategy to supply water to the Turbine Driven Emergency Feedwater Pump in the event the CST is rendered unavailable. The request for relaxation is based on the time required to design and implement the new alternate EFW suction modification, update FLEX procedures, and complete operations training. The request for schedule relaxation was submitted in a separate document in August 2015 (i.e.,

Reference 8 in Section 8).

6 Open Items The NRC audit team concluded the onsite portion of the Mitigating Strategies Audit on July 17 th, 2015. The following table provides a summary of FLEX related items which remained open at the time of the audit's exit meeting and the status of those items at the time of this report.

Audit Item Reference Item Description Status ISE Cl 3.2.1.2.A Confirm the acceptability of the use of the non- Pending (SE Tracker Westinghouse RCP seals in the Westinghouse RCPs; NRC endorsement Audit Item 8-A) provide justification for the RCP seal leakage rates for of white paper use in the ELAP analysis; and confirm the acceptability of 0-ring performance under high temperature conditions expected during an ELAP event.

ISE Cl 3.2.4.8.A Electrical Power Sources/Isolations and Interactions - Closed (SE Tracker Confirm that the selected diesel generators are Audit Item 20-A) appropriately sized.

AQ 12 Provide the value of the maximum leak-off for each Pending (SE Tracker RCP seal in gpm assumed in the ELAP analysis. NRC endorsement Audit Item 12-B) of white paper

Document Control Desk Enclosure RC-1 5-0125 CR-I12-01078 Page 7 of 8 Audit Item Reference Item Description Status AQ 55 The staff has concerns on the long term reliability of Information provided (SE Tracker the turbine/steam driven AFW pump during an ELAP on E-portal Audit Item 55-B, event. Specifically address the following:

part a) a. Excessive moisture in the steam supply can disrupt turbine operation. Typically steam traps remove this excessive moisture. However, the condensate return lines from these traps can be isolated or crimped during an ELAP event. Provide a discussion on how the steam traps will continue to operate during an ELAP event ifthe condensate header is isolated or can become isolated during an ELAP. If the condensate discharges to a local sump, please address long term area temperature and humidity along with the removal of the condensate before local room flooding can occur.

SE Review The licensee is requested to provide a summary Closed Item evaluation to confirm that temperature and pressures (SE Tracker within containment will not exceed the equipment Audit Item 14-E) qualification of electrical equipment including Power Operated Relief Valves that are being relied upon as part of their FLEX strategies. The licensee needs to ensure that the qualified profile of the required electrical equipment remains bounding for the entire duration of the event.

7 Potential Draft Safety Evaluation Impacts There are no potential impacts to the Draft Safety Evaluation identified at this time.

8 References The following references support the information contained within this enclosure.

1. SCE&G Letter, Virgil C. Summer, Unit 1, Overall IntegratedPlan as Required by March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA 049), dated February 28, 2013, Agencywide Documents Access and Management System (ADAMS) Accession Number ML13063A150

2. NRC Nuclear Regulatory Commission (NRC) Order Number EA-12-049, Issuance of Orderto Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, dated March 12, 2012, ADAMS Accession Number ML12054A735

Document Controi Desk Enclosure RC-15-0125 CR-12-01 078 Page 8 of 8

3. SCE&G Letter, Virgil C. Summer, Unit 1, First Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (OrderNumber EA 049), dated August 28, 2013, ADAMS Accession Number ML13242A273

4. SCE&G Letter, Virgil C. Summer, Unit 1, Second Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated February 27, 2014, ADAMS Accession Number ML14063A203

5. NRC letter, Virgil C. Summer Nuclear Station, Unit 1 - Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigation Strategies), dated February 21, 2014, ADAMS Accession Number ML14034A339

6. SCE&G Letter, Virgil C. Summer, Unit 1, Third Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA 049), dated August 28, 2014, ADAMS Accession Number ML14245A405

7. SCE&G Letter, Virgil C. Summer, Unit 1, Fourth Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA 049), dated February 27, 2015, ADAMS Accession Number ML15062A007

8. SCE&G Letter, Request for Schedule Relaxation from NRC Order EA-12-049, "Order Modifying Licenses With Regard To Requirements For Mitigation Strategies ForBeyond-Design-BasisExternal Events," dated August 13, 2015 9 Attachments

1. Revised Section 4, Sequence of Events and Technical Basis, and Attachment 1A, Sequence of Events Timeline of the Overall Integrated Plan

2. Revised Conceptual Sketches of Strategies

Document Control Desk Enclosure Attachment 1 RC- 15-0125 CR-i12-01078 Page 1 of 13 VIRGIL C. SUMMER NUCLEAR STATION, UNIT I RC-15-0030 ENCLOSURE ATTACHMENT I REVISED SECTION 4, SEQUENCE OF EVENTS AND TECHNICAL BASIS, AND ATTACHMENT IA, SEQUENCE OF EVENTS TIMELINE, OF THE OVERALL INTEGRATED PLAN

Document Control Desk Enclosure Attachment 1 RC-1 5-0125 CR-i12-01078 Page 2 of 13 Section 4: Sequence of Events and Technical Basis Provide a sequence of events Strategies that have a time constraintto be successful and identify any time constraint should be identified with a technical basis and a requiredfor success including justi~ficationprovided that the time can reasonablybe met the technical basis for the time (for example, a walkthrough of deployment).

constraint. Describe in detail in this section the technical basisfor the time constraintidentifed on the sequence of events timeline Ref: NE1 12-06 Section 3.2.1. 7 Attachment lA JLD-ISG-2012-01 Section 2.1 See attachedsequence of events timeline (Attachment JA).

Technical Basis Support information, see attachedNSSS Signi~ficantReference Analysis Deviation Table (Attachment iB)

General :

1. FLEX Response at VC Summer is governed by EOP-6.0, ECA-0.0 Loss of All ESF AC Power and FSP-5.O, InitialAssessment and FLEX Equijpment Staging. These two procedures are the controlling documents for Phase 1, 2 and 3 FLEX Response. The sequence of events is constructed based on assumed progression through these procedures.

2. WCAP-1760 1-P (Reference 7) envelops the plant for thermal hydraulic issues. This is verified per PWROG Core Cooling Position Paper Revision 0; section II (Reference 6). In order to minimize any leakage, and to lower RCS and Steam Generator feed pressures, the plant will be cooled down. Although plant cooldown is not required to be performed quickly after the event, due to the performance of low leakage Flowserve N9000 RCP seals, VCS will take prompt action to cooldown (within 2 - 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />). Cooldown is desirable for long term survivability of the RCP seals and to allow use of FLEX equipment at lower RCS and SG pressures. An analysis has been completed to determine the point at which two-phase natural circulation flow becomes less than single phase natural circulation flow, and the point at which reflux cooling will begin, since RCP seal leakage is 2.5gpm per pump. For VC Summer, using low leakage RCP seals, RCS makeup must occur by T=20 to meet this criteria.

3. Boration calculation (Reference 47) for the present core indicates that boration is not required for maintaining 260 psig in the steam generators for the first 28 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br />. Assuming 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> for mixing, boration must be complete by hour 27. Based on calculated time to reach Reflux Cooling, boration will be complete well in advance. The Boration Calculation includes a 25% margin to ensure it will bound all future core designs, and therefore not require update each cycle. Steam Generator pressure and RCS Temperature will be stabilized at these conditions to complete required boration prior to subsequent RCS cooldown to 350 degF.

4. If possible, stripping of the DC buses will be avoided by powering the battery chargers from FLEX equipment within approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. If the batteries are not charging, then stripping

Document Contra! Desk Enclosure Attachment 1 RC- 15-0125 CR-i 2-01078 Page 3 of 13 must be initiated at approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, and completed by 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after losing charging capability (Reference 8).

5. Room temperature profiles with loss of ventilation have been calculated for the Control Room (Reference 9), Relay Room (Reference 10), and the Turbine Driven Emergency Feed Pump Room (Reference 11).

6. The TDEFW pump requires no support systems (no DC power, instrument air, or additional cooling is required (it is cooled by the pumped fluid)). The TDIEFW pump operation usually requires no operator action; it starts and runs at the preset speed. The only time station procedures call for local speed control is if the flow control valves are impaired.

7. A new digital radio system will be installed in 2015, and will be tested per MTP-50856.01 to ensure adequate performance.

8. Battery room parameters, including temperature and hydrogen generation, have been evaluated per References 12 and Reference 13.

9. Condensate Storage Tank (CST) depletion times are documented in Reference 14, Reference 47, and in Technical Specification Basis.

10. Accumulator venting or isolation must be completed to perform second stage of cooldown to final long term cooling conditions.

11. Containment integrity was reviewed by Reference 15.

12. A best estimated decay heat curve was developed per Reference 16.

13. Per 10 CFR 50.63 and Regulatory Guide 1.155, VCSNS is a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping plant, with an alternate ac capability. Applicable portions of supporting analysis have been used in ELAP evaluations.

14. The FLEX breakers for XSW1DA and XSWlDB must remain racked up on their associated switchgear to maintain the seismic qualification of the breakers. To accommodate this, Class 1E equipment will be protected from faults in FLEX equipment by administrative controls which ensure the 7.2 kV breaker can only be locally controlled, that its normal position is OPEN, the Closing and Tripping Control Power Breakers are OPEN, the associated fuses removed, and portable cables are disconnected.

15. There are no non-safety related installed mechanical components or equipment that will be

• credited in FLEX strategies. Newly installed non-safety related mechanical components or equipment required for FLEX-strategy implementation will be categorized as Quality Related and will be qualified to survive ELAP events.

Discussion of time constraints identified in Attachment 1A A detailed discussion of Time Constraints is provided in VCSNS Technical Report (TR),

TR00080-006, FLEX Timeline Constraints Basis (Reference 49). The following information provides a brief summary of that evaluation:

Document Control Desk Enclosure Attachment 1 RC-1 5-0125 CR-i 2-01078 Page 4 of 13 Table Item 7 - Assess Communication Systems and Deploy Portable Comm Tower: If onsite radio communications are degraded, use of a portable radio tower will enhance communications. Communication between the Control Room Staff and field operators should be established to conduct an effective/symmetric cooldown.

Table Item 9 - Align Alternate EFW Suction Source: If the CST is damaged, an alternate suction source must be aligned to the TDEFP to maintain SG Feed for core cooling. Assuming an instantaneous loss of feed, the time to dryout the SGs is 61 minutes. Restoration of EFW flow within one hour will ensure core uncover does not occur.

Table Item 11 - Control Emergency Feed: Simulator shows that steam generators reach above normal levels, with no throttling of the EFW flow control valves, in approximately 45 minutes at Beginning of Core Life (longer at End Of Life (EOL)). Air accumulators for the EFW flow control valves are sized to allow remote closure for up to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. Coarse SG Level control can be maintained in this manner until local control is established. Control of EFW will be a high priority for the Control Room Staff if Instrument Air is not available. If air is available, remote operation of the EFW flow control valves will be maintained, even in the event that DC load shedding is required.

Table Item 12 - Strip X-Train DC Loads: EOP-6.0, directs shedding of non-essential DC loads to prolong the life of the Station Non-lE Battery, XBA1iX. Included in the loads that are shed is the Emergency Seal Oil Pump, which provides Seal Oil to the Main Generator Hydrogen Seals, to keep Hydrogen contained within the Main Generator. Controlled venting of Main Generator allows securing of the ES OP (and other DC bearing oil motors) to prolong the life of XBA1X. Without this load shedding, XBA1X will last only 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, at which point Hydrogen would be released into the Turbine Building if these actions are not completed.

Table Item 13 - Establish Relay Room Cooling: Refer to TR00080-006, FLEX Timeline ConstraintsBasis.

Table Item 14 - Declare ELAP: Time period of two (2) hours is selected conservatively to ensure that ELAP entry conditions can be verified by control room staff, and it is validated that the alternate source AC (an underground line to XTF5052 fed from either the Parr 115 kV grid or the Parr Hydro plant) is not available. This is a reasonable assumption since Parr Hydro is not continuously manned and has to be manually started by local operators. Parr Hydro response time meets requirements of NUJMARC 8700 Appendix B. ELAP entry conditions are:

I. Loss of Offsite Power II. Loss of all Emergency Diesels III. Loss of Alternate AC TV. Any doubt exists that normal 7200 VAC power can be restored within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of event Table Item 16, 17, 19 - Energize Station Batteries or Perform DC Load Shed: DC load shed must be complete within four hours in order to maintain consistency with assumptions for coping time evaluations (Reference 8). Reference 28 provides the load profiles for before, during, and after the initiating event and the load profile after load shedding is completed

Document Control Desk Enclosure Attachment 1 RC-1 5-0125 CR-i12-01078 Page 5 of 13 (calculation conservatively assumes full DC load until load shedding is complete). Assuming the completion of load shedding occurs at T=4 hours results in an estimated total battery life of 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> (i.e. 11 additional hours of life after load shedding is completed). The calculation also lists the breakers that need to be opened. Station Operators have performed timed walk downs to confirm these actions can be completed within one hour of initiation.

Table Item 18- Perform Cooldown: The anticipated characteristics of the Flowserve Ng000 seals provide flexibility in the decision making for timing of the RCS cool down and de-pressurization. The 2-4 hour timing of the cooldown was to allow additional flexibility in manpower priorities, if required, and is supported by WCAP 17601, Section 5.7.1. The plant cooldown will be prioritized after feedwater and battery charging is assured. The cooldown will commence between 2 and 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after the event and will not be purposefully delayed. The initial cooldown, directed by EOP-6.0, stops at a Steam Pressure of 260 psig, to ensure the RCS is promptly cooled. The cooldown is stopped to allow isolation of SI Accumulators (or venting) to prevent nitrogen injection into the RCS which could interrupt Natural Circulation. Local operation of SG PORVs is the credited method for performing the cooldown. However, if instrument air is available, the SG PORVs can be controlled remotely from the Control Room.

The time restraint, associated with this activity, ensures the assumptions, made in Design Calculations supporting RCS boration, CST depletion, and Reactor Building heatup, are maintained and valid.

Table items 20-27, 33-35 Establish Natural Circulation or Forced Ventilation: Procedures have been developed to address ventilation requirements in various areas of the plant to support local operator actions or equipment concerns. The strategies consist of restoring forced ventilation if AC power can be restored from a FLEX source with alternatives of establishing natural circulation and portable fans. This is necessary to ensure both Equipment Reliability and Operator Habitability in some areas. Refer to TR-00080-006, FLEX Time line Constraints Basis.

Table Items 29 & 31 - Refill the CST or Supply Low Pressure SG Feed: Numerous methods are available to reffill the CST, which is the easiest method for assuring a continued suction supply for the TDEFP, which is assumed to survive all events. CST level will last significantly longer at normal levels. If the CST empties or is otherwise unavallable, the low pressure Flex Transfer pump(s) must be placed in service. Per WCAP- 17601-P (Reference 7), steam generator dryout time will exceed two hours from the time the CST empties; this conservatism is not included in the Time Constraint. If it were, at least 10.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> would be avallable before the SG Feed Pump would be required to be placed in service. Typically the CST can be filled from onsite demineralized water or filtered water tanks or from a low pressure water source (Lake Monticello via fire service), or the Service Water Pond (ultimate heat sink) for seismic events.

Table Item 30- Isolate or Vent the SI Accumulators: This is not a Time Constraint, but more of a Progression Restralnt. The Cooldown from 409 degF to 350 degF is not time critical. The initial cooldown will enable use of FLEX strategies and minimize RCS leakage. Subsequent cooldown to the minimum SG pressure to support TDEFP operation is recommended but oniy after Boration is complete and the SI Accumulators are isolated, to prevent nitrogen injection into the RCS.

Document Control Desk Enclosure Attachment 1 RC-l15-0125 CR-12-01 078 Page 6 of 13 Table Item 32 - Refuel FLEX Equipment: Lowest Fuel Capacity of FLEX equipment is Ultimate Heat Sink (UHS) System which could be deployed for CST Fill at time T+6 and would require refueling 9.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> later. Other large FLEX Pumps have > 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> onboard capacity. Each Combustion Turbine Generator (CTG) has a fuel capacity of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> and only needs continuation of an already implemented fuel strategy. This fuel strategy is performed by a CTG operator already stationed at the CTG.

Table Item 36- Boration: Boration is required for VCSNS due to cooldown. Boration will be completed in the timeframe before hour 28 (Reference 47). The volume of borated water injected is based on maintaining shutdown margin for 350 degF in the RCS, but the Time Constraint is based on achieving 409 degF because this temperature cannot be maintained indefinitely without some form of boration (though this is a smaller volume than what is required for 350 degF). Once boration is started, it should be continued until the required concentration for 350 degF is reached. Much like the plant normally borates for cold shutdown, Xenon free concentration before entering Mode 5, the same approach is used here, prior to achieving 350 degF.

Table Item 40 - Makeup to Spent Fuel Pool: Boiling will start at 20-24 hours, with a boil off rate of approximately 2 inches per hour. See Reference 18 and 49.

Attachment lA: Sequence of Events Timeline Action Elapsed Time Time Time* Action Constraint Constraint Reference RemarkslApplicability Itm (hours) YIN (hours) 0 Event Starts N/A ......

SBO Procedure Reference EOP-6.0 is direct entry 1 0 (EOP 6.0) N -- 17poeu.

Entered17poeu.

TDEFW starts, Automatic on Blackout, 2 0.017 blowdown N - RCS temperature isolates controlled by MS Safeties.

Letdown isolates References automatically if air is 3 007 Isolate the RCS N -17 & 51 lost, otherwise this is performed from Control Room.

Document Control Desk Enclosure Attachment 1 RC-1 5-0125 CR-I 2-01078 Page 7 of 13 Attachment lA: Sequence of Events Timeline Action Elapsed Time Time Time* Action Constraint Constraint Reference Remarks/Applicability Itm (hours) YIN (hours)

Preparatory actions to

. seBs Pttsowe N- Reference identify preferred AsEss SttsofeN 17 method of re-charging Station Batteries.

Assess & Stage N - Reference Preparatory actions 5 0.5 CTGs and Fuel N17 only, not connecting to Supply plant equipment.

AssssReference Inside and outside 6 0.5 deployment N -1prtceae.

routes 1 rtce ra Assess Communication should Communication be established early to Systems, Deploy coordinate FLEX 7 0.5 Portable Y T+4 -- response (should be Communication performed before Tower if cooldown is necesarycommenced, at a necesaryminimum).

RCP seal CBO flow Isolate RCP cannot be isolated Reference 8 0.5 Seals N -- 17 (fails open). CBO flow redirected to PRT' instead of VCT.

0.5 Align Alt EFW yT+1 Reference Required only if CST is Suction 17 & 53 not available.

Isolate CST from 10 075 he Min -- Reference Conserves inventory in Condenser 17 CST.

At full TDEFP flow, SGs take approx. 45 Control Reference minutes to fill to 80%

11 0.75 Emergency Y T+1.5 17 NR. Each EFW FCV Feed &Smltrhas an air accumulator to allow closure for up to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.

Document Control Desk Enclosure Attachment 1 RC-15-0 125 CR-12-01 078 Page 8 of 13 Attachment lA: Sequence of Events Timeline Action Elapsed Time Time Time* Action Constraint Constraint Reference Remarks/Applicability Itm (hours) Y/N (hours)

Strip X Train DC Controlled vent allows Reference securing ESOP and 12 1 Lads-VenertorT+ 17 conservation of Non-Main ogeneao 1E DC Power. XBA1X HydrogenBattery life is 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

Establish Relay References Prevent loss of control 13 1 Room Cooling y T+I O1 uthauo (Natural s0&17 denstiv electrponis Circulation) sniieeetois Crew is allowed two hours to determine if References AC power can be 14 Dclae LAPY +2 17, 21, 28 recovered. By T=2 hours, decision made by SS that an ELAP exists.

15 onac NRCReference Notify NSRC to 15Cntct SR2N1-mobilize equipment for 21 VCS.

Energize Station At least one battery' Reference charging strategy must 16B Batterie yrmYT1 21, 28 be complete before EBhattery Station Batteries are Chargersexhausted.

Energize Station Batteries from At least one battery Reference charging strategy must 17 2 Station Battery y T+15 2,8 b opeebfr Chargers, StationeBatplteres aefre powered from exhausnated.s r CTGs ehutd

Document Control Desk Enclosure Attachment 1 RC-15-0125 CR-I12-01078 Page 9 of 13 Attachment lA: Sequence of Events Timeline Acin Elapsed Time Time Item Acin(hours)

Time* Action .. Constraint YIN Constraint (hours) Reference Remarks/Applicability With low leakage RCP Perform seals, immediate Cooldown Reeecs cooldown is not 18 2Y T+6 Reeecs required, but cooldown

~75degF/hr to 7 &17 will start at 2to 4

~260 psig steam hours, and be pressure accomplished within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after the event.

Required to be Perform DC load Reference completed within 4 19 3 stripping. Y T+4 21, 28 hours of event start, if station batteries are not re-energized.

Establish TDEFP Room 20 3 Cooling YT+4 Reference To maintain equipment (Ntrl49 reliability.

Circulation)

Establish EFW FCV area 21 3Cooling YT+4 Reference To maintain operator (Ntrl49 habitability.

Circulation)

Establish SG PORV Area 22 3Cooling yT+4 Reference To maintain operator (Ntrl49 habitability.

Circulation) 77 hours8.912037e-4 days <br />0.0214 hours <br />1.273148e-4 weeks <br />2.92985e-5 months <br /> after Establish Battery charging capability is Room Reference restored, H2 23 3Ventilation Y T+77 cnetaini (Forced) battery room approaches 2%.

Document Control Desk Enclosure Attachment 1 RC-15-0 125 CR-i12-01078 Page 10 of 13 Attachment 1A: Sequence of Events Timeline Action Elapsed Time Time Itm Time* Action Constraint Constraint Reference Remarks/Applicability Itm (hours) YIN (hours)

Establish Battery To maintain equipment Charger Room Reference reliability. Only 24 ColngY9+4required if CTGs used (Natural to re-energize Station Circulation) Battery Chargers.

Establish ESF To maintain equipment Switchgear Reference reliability and operator 25 3 1DA/B Room Y T+12 49habitability. Only Cooling required if CTGs used to re-energize Station (Forced) Battery Chargers.

Establish SF Pool Area Reference To maintain operator 26 3 Cooling (Natural 49T21habitability.

Circulation)

Establish AB-463 North Area 27 3 Cooling YT+14 Reference To maintain equipment 49 reliability and operator (Natural habitability.

Circulation)

Complete Assessment of plant 28 6 Walkdowns and N-- damage should be Assessment of complete by end of cooldown to prioritize plant. subsequent actions.

At T/S minimum volume, must either refill CST or go on 29 6 Perform CST yT+8.4 Reference alternate low pressure refil 14 feed by T=8.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

CST inventory should last 64+ hours if at normal level.

Document Control Desk Enclosure Attachment 1 RC-1 5-0125 CR-12-01 078 Page 11 ofl13 Attachment lA: Sequence of Events Timeline Action Elapsed Time Time Itm Time* Action Constraint Constraint Reference Rem arks/Applicability Itm(hours) .. YIN(hus Progression restraint -

30 6 Isolate or Vent N -- Rfrne cannot cooldown SI Accumulators 17 further until isolation or venting performed.

Required only if unable 31 6 Perform Low References toflOTrohe Pressure SG YT84 2 & 17 loss of emergency feed feed.

Based on UHS pump 32 ReuelFLE T+5.4 Reference needing fuel first, if in Equipment 21 service. All others FLEX pumps have >

12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> fuel capacity.

Establish Control Room 33Cooling YT+8 Reference To maintain operator 33 649 habitability.

(Natural Circulation)

Establish Control Room Reference To maintain operator 34 6Cooling Y T+12 4 aiaiiy (Forced)

EstabmColish Relay2 Reference To maintain equipment 35 RomColngYT+249 6 reliability.

(Forced)

Document Control Desk Enclosure Attachment 1 RC-1 5-0125 CR-12-01 078 Page 12 of 13 Attachment 1A: Sequence of Events Timeline Action Elapsed Time Time Itm Time* Action Constraint Constraint Reference Remarks/Applicability Itm (hours) . YIN (hours) ..

Longest boration option requires 17.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to inject.

Boration must be accomplished by T+28 36 10.5 yT+20 References hours to maintain 409.

Boration T+27 23 & 47 degF, assuming 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> for mixing. Boration must be complete by T=27 hours. Also, must be initiated by T=20 hours.

Continue methods of RCS makeup Establish Long established during boration. Time to 3 175 Term RCS T+9 References 3 175 Inventory Y +95 17, 23, 49 reflux cooling is 39.5 Control hours and time to uncover core is 80.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> if RCS makeup is not achieved.

If ASI survives, it's desirable to continue 3 175 Establish RCS N - Reference to supply RCP Seal Letdown 50 Cooling. Must establish letdown to accommodate.

Long Term Cooling conditions (minimum Depressurize SG pressure for SGs to 170 psig References continued operation of 3 175 for Long Term N -17 & 23 TDEFP) - RCS must Cooling be borated, Accumulators must be isolated.

Document Control Desk Enclosure Attachment 1 RC-1 5-0125 CR-i12-01078 Page 13 of 13 Attachment lA: Sequence of Events Timeline Action Elapsed Time Time Itm Time* Action Constraint Constraint Reference Remarks/Appl icability Itm (hours) YIN (hours)

Time to boil in SFP conservatively 40 18 Begin SF Pool y T+87 Reference estimated at 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br />.

makeup 49At 2.06 in/hr boiloff, time to L2 (l0ft above fuel) is 87 hours0.00101 days <br />0.0242 hours <br />1.438492e-4 weeks <br />3.31035e-5 months <br />.

NSRC Water Improve Water Treatment equipment 41 24+ Quality for long N -Ref 52 delivered to improve term SG Feed water quality if source is Lake or SW Pond.

RB cooling not required for > 30 days Establish RB Reference t rvn xedn 42 24+ Cooling N T+30 days 49design temp/press limits but will be established when AC power is available.

• Note - Elapsed time is an estimate only. Final disposition of the start times and margin to completion for the sequence of events will be determined after completion of Validation activities and documented in VCSNS TR00080-007, VCS FLEX Validation Document. The results will be included in the Final Implementation Plan.

Document ControJ Desk Enclosure Attachment 2 RC-1 5-0125 CR-i12-01078 Page 1 of 8 VIRGIL C. SUMMER NUCLEAR STATION, UNIT 1 RC-1 5-0125 ENCLOSURE ATTACHMENT 2 CONCEPTUAL SKETCHES OF STRATEGIES

Document Control Desk Enclosure Attachment 2 RC- 15-01 25 CR-i12-01078 Page 2 of 8 Figure 4 - Conceptual Strategy for Reactor Makeup and Reactivity Control

1) Solid lines are existing piping and SSCs

2) See Figure 11 for conceptual schematic of the diverse RCS makeup sources and pumps.

Document Control Desk Enclosure Attachment 2 RC- 15-0125 CR-i12-01078 Page 3 of 8 Figure 5 - Conceptual Coping Strategies for Support Functions from EB

-. zLElectrical Building (EB)an Auxiliary Electrical Building (AEB) are designed to NEI 12-06 standards for a protected structure and will supply power for Phases 1, 2 & 3 support functions.

AEB.%..-

0 EB

Document Control Desk Enclosure Attachment 2 RC-15-01 25 CR-I12-01078 Page 4 of 8 Figure 7 - Conceptual Strategy for Supplying SG Makeup Using Alternate EFW Suction CST IEMERGENCY FEEDWATER

'FLOW CONTROL VALVESf*" ***"-

(1B-423) r-i-i::I -'i1i---

SG

___ .__B SW B MDEFP B Suction Piump (x 2)

(swPH-425) SW POND

Document Control Desk Enclosure Attachment 2 RC- 15-01 25 CR-i12-01078 Page 5 of 8 Figure 8 - Conceptual FLEX Feed Hose Layout Pond

Document Control Desk Enclosure Attachment 2 RC-15-0125 CR-I12-01078 Page 6 of 8 Figure 11 - FLEX Strategy Conceptual Mechanical Diagram (O)l*ttl*l]*

MDEFW Pump*s nEFW PImp s)I Pump MDl IX '.O MU Irnp f'XPP25 ) MOdES14

Document Control Desk Enclosure Attachment 2 RC-15-0125 CR-i12-01078 Page 7 of 8 Figure 12 - FLEX Strategy Conceptual Electrical Diagram

Document Control Desk Enclosure Attachment 2 RC- 15-0125 CR-i12-01078 Page 8 of 8 Figure 14 - FLEX Storage and Deployment Site Plan