Text

(VCSNS) Unit 1- Sixth 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)
	ML16061A005
Person / Time
Site:	Summer
Issue date:	02/26/2016
From:	Lippard G; SCANA Corp, South Carolina Electric & Gas Co
To:	; Office of Nuclear Reactor Regulation
References
	CR-12-01078, EA-12-049, RC-16-0004
	Download: ML16061A005 (33)
	v • d • e

George A. Lippard Vice President, Nuclear Operations

_____________(803) 345-4810 A SCANA COMPANY February 26, 2016 RC-l16-00 04 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555-0001

Dear Sir / Madam:

Subject:

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 SIXTH 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 Order to 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-2012-01, 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 MLI2229A1 74

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 External Events (Order Number EA-12-04 9),

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 Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated February 28, 2013, ADAMS Accession Number ML13063A150 On March 12, 2012, the Nuclear Regulatory Commission issued Order EA-12-049 (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

-1 V. C. Summer Nuclear Station *.RO. Box 88. I enkinsville, SC, 29065.* F (803) 941-9776

Document Control Desk RC-1 6-0004 CR-i12-01078 Page 2 of 2 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 (Reference 2) and an Overall Integrated Plan (OIP) pursuant to Section IV, Condition C.1. Reference 2 endorses industry guidance document NEI 12-06, Revision 0 (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 OIP. Reference 3 provides direction regarding the content of the status reports.

The purpose of this letter is to provide the sixth 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.

Executed on G /ge."p PF/GAL/wm Enclosure Virgil C. Summer Nuclear Station (VCSNS) Unit 1-Sixth 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) c:

K. B. Marsh S. A. Williams (w/attachments)

S. A. Byrne M.O0. Valentin (w/attachments)

J. B. Archie NRC Resident Inspector N. S. Cams K. M. Sutton J. H. Hamilton NSRC J. W. Williams RTS (CR-12-01 078)

W. M. Cherry File (815.07)

C. Haney (w/attachments)

PRSF (RC-16-0004)

Document Control Desk Enclosure RC-16-0004 CR-I12-01078 Page 1 of 31 VIRGIL C. SUMMER NUCLEAR STATION UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 ENCLOSURE SIXTH 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-16-0004 CR-i12-01078 Page 2 of 31 I

Introduction South Carolina Electric & Gas Company (SCE&G) developed an Overall Integrated Plan (OIP)

(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 (Reference 2 in Section 8). Subsequently, SCE&G provided the first, second, third, fourth and fifth six-month status reports (References 3, 4, 5, 6, and 7 in Section 8, respectively). This report, the sixth 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 August 16, 2015, and February 15, 2016, hereafter referred to as the "update period."

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

Submit 6-month update Walk-Throughs or Demonstrations Unit 1 Implementation Outage Storage Implementation 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 table has been modified during this update period to reflect the addition of an alternate Emergency Feedwater (EFW) modification and changes to the full implementation schedule requirement (see Section 5 for more information). The dates are planning dates subject to change as design and implementation details are developed.

Milestone completion Activity St~atus, Complretio 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 Complete

Document Control Desk Enclosure RC-16-0004 CR-i12-01078 Page 3 of 31 Miestone /

Cornpletion AcivtyStatUs Completion Date D

!or atel FLEX Strategy Evaluation Aug 2013 Complete Walk-Throughs or Aug 2015 Complete Oct 2015 Demonstrations Perform Staffing Analysis Jul 2014 Complete Jul 2015 Modifications:

Modifications Evaluation Dec 2013 Complete Unit 1 Design EngineeringJa205Cmlt EvaluationJa215Cmlt Unit 1 Implementation Outage Nov 2015 Complete Dec 2015 Alternate EFW Modification Jul 2016 In Progress Jul 2016 Storage:

Design Storage Building Jul 2014 Complete Mar 2015 Storage Implementation Jul 2015 Complete Sep 2015 FLEX Equipment:

Complete with exception Procure On-Site Equipment Oct 2014 of the Alternate EFW Jul 2016 Strategy Develop Strategies with RRC Nov 2014 Complete Install Off-Site Delivery Station Au203Cmlt (if Necessary)Au203Cmlt Procedures:

PWROG issues NSSS-specific Ma203Cmlt guidelinesMa203Cmlt Complete with exception Create Site-Specific FSPs Feb 2014 of the Alternate EFW Jul 2016 Strategy Creae MantennceComplete with exception Crae anenneOct 2014 of the Alternate EFW Jul 2016 Procedures Strategy Training:

Develop Training Plan Jan 2015 Complete Mar 2015

Document Control Desk Enclosure RC-16-0004 CR-I12-01078 Page 4 of 31

!Revise M ileston opein Atvt ttsCmlto Complete with exception Training Complete Jul 2015 of the Alternate EFW Jul 2016 Strategy Complete with exception Unit I FLEX Implementation Nov 2015 of the Alternate EFW Jul 2016 Modification Submit Completion Report Jan 2016 Not Started Sep 2016 4

Changes to Compliance Method No changes to the compliance method as documented in the Overall Integrated Plan (Reference 1) or to the changes that were submitted in References 3, 4, 5, 6, or 7 of this status report were made during this update period.

5 Need for RelieflRelaxation and Basis for the RelieflRelaxation In a letter to the NRC, VCSNS Unit I requested a schedule relaxation of the requirement for full implementation of Order EA-12-049 (Reference 8 in Section 8). The NRC responded to the request, relaxing the requirement of the order for full implementation for VCSNS Unit 1 until July 3 1st, 2016 (Reference 9 in Section 8).

6 Open Items The responses to NRC Interim Staff Evaluation (ISE) open and confirmatory items identified in Reference 10 are provided below. All items with the exception of item Cl 3.2.1.2.A were considered closed, as documented in the NRC's audit report (Reference 11). Item Cl 3.2.1.2.A is considered complete pending NRC closure.

IS

....... Item I tem De scrip...

ion....

Response.........

0I ELAP Analysis The Pressurized Water Reactor Owner's Group 3.2.1.1.A Computer Code -

(PWROG) produced PWROG-1 4064-P which covers the Confirm the application of the NOTRUMP computer code to the identification of the extended loss of alternating current (AC) power (ELAP) codes utilized for event. The full details of the concerns are covered in that ELAP analysis and document and not repeated here. With the installation of the adequacy of the the N9000 seals these issues are simply addressed by technical basis to determining the mass loss from the reactor coolant support the system (RCS) prior to the start of makeup. If the mass conclusion that the loss is lower than the amount that would lead to the onset codes are sufficient to of reflux cooling, then NOTRUMP application is predict whether the appropriate.

Document Control Desk Enclosure RC-1 6-00 04 CR-i12-01078 Page 5 of 31 ISE: Item

],,*::*tem Descriptio jepos intended mitigating strategies would adequately cool the reactor core. If the codes and methods were previously approved by NRC, provide the references to the safety evaluations (SEs) approving the codes and methods, and address compliance with the restrictions and conditions imposed in the SEs on the use of the codes and methods.

Additionally, confirm the specific analyses used to demonstrate adequate core cooling for VCSNS.

PWROG-14027-P provides the guidance to determine the onset of reflux cooling. For a three-loop plant with standard Westinghouse seals the time is 9.2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . With the N9000 seals, the seal leakoff (referred to as Controlled Bleed Off (CBO)) is substantially less than that used in the calculation. PWROG-14027 provides the methodology for accounting for low leakage seals. It is simply a mass balance. The total mass loss from the onset of ELAP until makeup is provided must be less than the allowable mass loss. For a three loop plant from PWROG-1 4027:

Total Mass =412000 lb Onset of Reflux Mass = 272000 lb Allowable Mass Loss = 140000 lb Assuming the N9000 CBO is constant at 2.5 gpm per pump and 1 gpm unidentified leakage, the volumetric coolant loss is 8.5 gpm. As RCS pressure decreases, both CBO and unidentified leakage should decrease.

Holding them constant is conservative. The mass flow rate is determined based on the density of water in the RCS cold legs. Note that the higher the density, the higher the mass loss. The following data from letter CGSV-15-0001 is used; 0 to 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months s:

Steam Generator Pressure = 1176 psig +

1% accumulation Tsat = 567° F 4 to 26 hour3.009259e-4 days 0.00722 hours 4.298942e-5 weeks 9.893e-6 months s: RCS temperature = 409°F (conservative to assume instant cooldown) 26 hour3.009259e-4 days 0.00722 hours 4.298942e-5 weeks 9.893e-6 months s:

Makeup is started for boration Mass Total Start Finish Temp Flow Mass (hour)

(hour)

(deg F)

(lb/mmn)

(Ib) 0 4

567 50.91 12217 4

26 409 60.56 79944 92162 Since a total mass loss of 92162 lbs is substantially below the 140000 lb limit, reflux cooling is not predicted to occur.

Therefore, the use of NOTRUMP is acceptable for the

Document Control Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 6 of 31 ISE Item Item Description

Response

VCSNS Unit 1 ELAP response.

01 Sequence of Events The Sequence of Events (SOE) has been revised to 3.2.1.6.A (SOE) -Complete the reflect strategy changes involving alternate emergency unresolved issues and feedwater (EFW) suction. The SOE includes a one hour future actions needed time critical action for alignment of alternate EFW suction to finalize the to the turbine driven emergency feedwater (TDEFW) sequence of events pump (CR-i14-05730-012). The basis for time sensitive for time constraint actions is documented in TR00080-006, "FLEX Time validation.

Constraint Basis."

CI In regards to FLEX coping strategies were developed to ensure at least 3.1.1.2.B protection of one connection point for the FLEX equipment will be connection access located within or attached to seismically robust structures.

points, confirm There is at least one seismically qualified suction source whether at least one and one discharge location accessible within seismically connection point for robust structures for each Phase 2 and Phase 3 coping the FLEX equipment strategy. These are seismically designed/analyzed and will only require are qualified as either Safety-Related or Quality-Related.

access through seismically robust structures accordance with the guidance of consideration 2 of NEI 12-06, Section 5.3.2.

Cl Confirm the analysis Multiple strategies are available to re-energize station 3.1.1.3.A for critical actions to batteries or station battery chargers from FLEX perform until alternate equipment. These strategies are directed from a Flex indications can be Support Procedure (FSP), FSP-5.0, "Initial Assessment connected and FLEX Equipment Staging," which ensures all vital (measured), how to instrumentation remains available from engineered safety control critical feature (ESF) inverters. Even in the event that these equipment without strategies are not successful immediately after control power, and the deployment, direct current (DC) load shedding is development of a performed per FSP-4.0, "ELAP DC Bus Load Shed reference source to Management," to conserve remaining station battery life obtain necessary for an additional 11 hours1.273148e-4 days 0.00306 hours 1.818783e-5 weeks 4.1855e-6 months (15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months total).

instrument readings.

FSP-4.0 provides instruction for performing DC load shedding to conserve battery life. Critical indications and control are not stripped during DC load shedding.

Document Control Desk Enclosure RC-16-0004 CR-12-01 078 Page 7 of 31 ISE lterm1 Item Description

Response

Indication of the following parameters will remain until the station batteries are completely exhausted: Steam Generator (SC) level, SG pressure, RCS wide range pressure, EFW flow, RCS Thot and Tcold wide range, reactor vessel level indication system (RVLIS),

condensate storage tank (CST) level, reactor building pressure, boric acid tank (BAT) level, refueling water storage tank (RWST) level, spent fuel pool (SEP) level.

Remote operation of TDEFW flow control valves and SG power operated relief valves (PORVs) remains available following DC load stripping as well, in the event that air is available.

F.SP-7.0, "Loss of Vital Instrumentation or Control Power,"

provides guidance for establishing alternate indication and control upon loss of DC power but is only expected to be necessary if power cannot be restored to station batteries within 15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months . FSP-7.0 contains direction to establish local control of EFW and SG PORVs for maintenance of core cooling strategies; however this would have already been established within 2-4 hours to facilitate plant cooldown if air is not available. VCSNS Unit 1 has a hydraulically controlled governor for the TDEFW pump, no local operator action is required to sustain operation upon loss of DC. FSP-7.0 also provides guidance to obtain alternate indication of critical parameters via instrument cabinets, penetrations or the transmitter itself. FSP-7.1, "Establishing Local Indication of Emergency Feed Flow,"

provides an additional method of obtaining alternate indication of EFW flow.

I-

-~

CI 3.1.3.1.A Confirm the analysis for local historical tornado data (width and path axis) has been taken into account with regard building locations.

VCSNS Unit 1 uses Option C as defined by Nuclear Energy Institute (NEI) 12-06, Section 7.3.1, for protection of FLEX equipment from wind hazards. The FLEX Storage Building (FSB) and the Emergency Response Building (ERB) are buildings constructed to ASCE 7-10 and are designed to withstand design basis hurricane winds. The buildings are not designed for the site design basis tornado wind loads or for the site design basis tornado generated missiles. The axis of orientation between the two primary storage structures is near the SW-to-NE axis, which is stated in NEI 12-06 Section 7.3.1 as generally the typical path of tornados in the US.

However, this arrangement is deemed acceptable for the following reasons:

Document Control Desk Enclosure RC-1 6-0004 CR-i12-010O78 Page 8 of 31 ISE Item Item Description

Response

-1 1

1) The location of the ERB is a compromise of proximity to Unit 1 and future Units 2 and 3. Staff and equipment located in this building are planned to respond to incidents at all units in the future.

2) The location of the FSB is optimal to minimize the distance between the FLEX equipment storage location and the FLEX equipment deployment locations and to avoid transporting equipment over potentially downed high voltage power lines. The FSB location in relatively close proximity to the power block and credited water sources minimizes the debris clearing and transit times for deployment of FLEX equipment. The location also minimizes the number of security barriers that are encountered during equipment deployment.

3) FLEX Guidance Inquiry Form (FAQ) 201 3-01 states that 1200 feet should be considered as the minimum separation distance for which further analysis is not required to justify diversity for sites located in Region 1 and Region 2 as shown in Figure 7-2 of NEI 12-06 (VCSNS is located in Region 1). The distance between the FSB and ERB is approximately 2400 ft, well in excess of the required distance.

4) The significant distance (~1 150 feet) between the FSB and the Diesel Generator (DG) Building and between the ERB and the DG Building (~-2400 feet) is sufficient to provide reasonable assurance that a tornado will not impact all locations of the DG Building, the ERB, and the FSB (See VCSNS Unit 1 drawing E-036-001, Revision 77, for Layout).

CI 3.1.3.2.A Confirm why NE! 12-06, Section 7.3.2, considerations 1 and 2 are not applicable to VCSNS.

Considerations 1 and 2 are applicable to VCSNS.

Consideration 1: VCSNS Unit 1 Operations Administrative Procedure (OAP)-i109.1, "Guidelines for Severe Weather,"

Step 6.3.c, provides thresholds to be used during threat of impending hurricane winds to commence plant shutdown to HOT STANDBY (Mode 3) in accordance with controlling site operations procedures. OAR-i109.1, Enclosure A, "Hurricane Action Timeline" provides a listing of actions to be taken prior to projected hurricane impact. Emergency Preparedness Procedure (EPP)-015, "Natural Emergency," Attachment Ill, is entered as required by OAP-1 09.1. EPP-015 directs the implementation of specific actions to prepare for hurricane

Document Control Desk Enclosure RC-1 6-0004 CR-I12-010O78 Page 9 of 31 ISE Itelm Item Description

Response

impact such as filling fuel oil tanks, securing potential missile hazards, additional staffing, etc. The site has no intentions of pre-connecting the FLEX equipment.

The FLEX equipment is stored in designated protected locations during postulated Extended Loss of AC Power/Loss of Ultimate Heat Sink initiating external events. The FLEX OIP timelines assume the equipment is stored in designated locations at the commencement of event.

Consideration 2: The ultimate heat sink (UHS) at VCSNS Unit 1 is contained within the Service Water Pond (SW Pond). The SW Pond is an enclosed body of water which is well separated from tree lines and is isolated from significant amounts of debris which could be postulated to result in blockage of normal SW paths. The SW Pond is protected from storm surge of bordering Monticello Reservoir by earthen dams and natural features. The plant and proposed access to the SW Pond is protected from storm surge by the West Embankment of the SW Pond. Debris equipment will be available on-site to ensure access to the SW Pond following high wind event. The FLEX UHS pump is a submersible pump which can be deployed to multiple locations of the SW Pond or the Monticello Reservoir.

CI 3.2.1.1.B Confirm that any use of the NOTRUMP code for the ELAP analysis of Westinghouse plants is limited to the flow conditions before reflux condensation initiates. This includes specifying an acceptable definition for reflux condensation cooling.

The NOTRUMP code results are applied selectively in recognition that Flowserve N-9000 low leakage, shutdown seals are used at VCSNS Unit 1. Their use greatly extends the core cooling coping time.

Primary makeup will be made available well in advance of the point at which reflux cooling will begin to ensure adequate boron mixing within the RCS. For ELAP simulations with NOTRUMP, VCSNS Unit 1 utilized the PWROG definition (PWOG-14064-P, Revision 0) for the onset of reflux cooling which is "when the one hour centered moving average (CMA) of the flow quality at the top of the SG U-tube bend exceeds 0.1 in any one loop."

Use of this SG quality plateau time as a surrogate for reflux cooling is conservative.

Cl Confirm the The Flowserve N-9000 seal is designed to meet/exceed 3.2.1.2.A acceptability of the the requirement of the Westinghouse reactor coolant use of the non-pump (RCP) seal. The American Society of Mechanical Westinghouse RCP Engineers Code and performance requirements of the

Document Control Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 10 of 31 ISE Item J Item Description JResponse seals in the Westinghouse RCPs and provide acceptable test results or other justification for adequate 0-ring performance under high-temperature conditions expected during an ELAP. The RCP seal leakage rate as a function of pressure for use in the plant specific ELAP analysis should be demonstrated to be valid via the results of acceptable testing.

N-9000 Seals are specified in DSP-667, "Reactor Coolant Pump Seal ASME III Class 1," and SP-1 003, "Reactor Coolant Pump Seal Assembly." These two specifications were developed based on the applicable sections of Westinghouse Specifications 677188 Revision 4 and 679103 Revision 5. The N-9000 seal meets/exceeds the pressure, temperature and seismic requirements of the Westinghouse seal. The seal leakage of the N-9000 seal is within the operating range of the RCP requirement as described in SOP-101 Enclosure B. The N-9000 seal has been installed in other nuclear power plants (North Anna and Surry) that use the same model of Westinghouse RCP and there have been no incompatibility issues reported. Therefore, using the N-9000 seal in the Westinghouse RCP is considered acceptable.

Flowserve's White Paper (ML15222A357) on the response of the N-Seal RCP seal package to an ELAP, Revision A, documented the seal flow rates during plant specific ELAP scenarios. The seal flow rate during ELAP depends on the degradation of the 0-rings which are made of ethylene propylene elastomers. The white paper determined that, under the VCSNS Unit 1 plant specific ELAP condition, the first elastomer failure may occur after 133.2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . According to the white paper, the seal leakage is 2.5 gpm per pump before the elastomer failure and is 4.2 gpm per pump (i.e. additional 1.7 gpm per pump) after the first elastomer failure. In the worst case scenario with significant failure in all the seal stages, the total seal leakage will be no more than 6.73 gpm per pump. These RCP seal leakage rates, with 1 gpm unidentified leakage, are much less than the 60 gpm of the makeup which will be available in 26 hours3.009259e-4 days 0.00722 hours 4.298942e-5 weeks 9.893e-6 months after the event. In other words, if the 0-ring fails after the makeup is available; the RCS leakage rates will remain well within the makeup capacity. Therefore, it is confirmed that the 0-ring performance is acceptable for the expected ELAP conditions.

The RCP seal leakage rate affects the RCS inventory in ELAP analysis. In TR00080-006, "FLEX Timeline Constraints Basis," 2.5 gpm of RCP seal leakage per pump is used to calculate the time to reflux cooling (39.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months ) and time to core uncover (80.7 hours8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months ). This 2.5 gpm leakage rate is consistent with the result of the white parer which determines that the N-9000 RCP seal J

P

Document Control Desk Enclosure RC-1 6-0004 CR-12-01 078 Page 11 of 31 iSE Item Item Description

Response

leakage for VCSNS Unit 1 is 2.5 gpm per pump before the potential first elastomer failure at 133.2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . The N-9000 Seal is equipped with Abeyance seal. Once actuated by a high velocity leakage, the Abeyance seal will close the gap between the seal and the shaft sleeve and stop leakage from the top seal to containment. If all the three seal stages fail due to temperature degradation of the 0-rings (which is not expected before the RCS make up is available), the seal leakage from the top seal can increase up to 4.23 gpm with another 2.5 gpm of CBO. After actuation of the Abeyance seal, the flow out of the RCP is limited to the CBO flow. In the event of ELAP, the RCS will be cooled and depressurized to approximately 350°F well before the potential first elastomer failure. Depressurization of RCS reduces the pressure differential across the seal stages and in turn reduces the OBO flow to less than 2.5 gpm. Therefore, using the 2.5 gpm seal leakage rate in the ELAP analysis is conservative.

CI 3.2.1.3.A Confirm the adequacy oftheANS 5.1-1979 +

2 sigma model analysis relative to the VCSNS. Specifically, specify the range within which the decay heat model is applicable for the following key parameters: (1) initial power level, (2) fuel enrichment, (3) fuel burnup, (4) effective full power operating days per fuel cycle, (5) number of fuel cycles, if hybrid fuels are used in the core, and (6) fuel characteristics (addressing whether they are based on the beginning of the cycle, middle of the cycle, or The decay heat used for the Westinghouse nuclear steam supply system (N SSS) calculations documented in WCAP-17601-P, Revision 1, and WCAP-1 7792 using the NOTRUMP code was calculated per American Nuclear Society (ANS) 5.1-1979.The following assumptions were applied to arrive at the overall normalized decay heat power:

1)

Two standard deviations of uncertainty.

2)

Three fissile isotopes of U-235, Pu-239 and U-238.

The total recoverable energy associated with one fission for each isotope is assumed to be 201.8 MeV, 210.3 MeV and 205.0 MeV, respectively.

3)

The power fractions are typical values expected for each of the three fissile isotopes through a three region burn-up with which the feed fuel U-235 enrichment is ~ 5%.

4)

Actinide contributions to the decay heat are from U-239 and Np-239. A conversion ratio of 0.65 was used to derive the production of the two actinides:

U-239 and Np-239.

5)

Fission product neutron capture is treated per the

Document Control Desk Enclosure RC-1 6-0004 CR-12-01 078 Page 12 of 31 ISE Item Item Description

Response

end of the cycle}.

ANS standard. Finite burnup that utilizes a power history of three 540 day cycles separated by two 20 day outages that bounds initial condition 3.2.1.2(1) of NEI 12-06, Section 3.2.1.2 (minimum assumption of NEI 12-06 is that the reactor has been operated at 100% power for at least 100 days prior to even initiation).

Plant specific ORIGIN2 calculations indicate that the decay heat fractions used in the WCAP NSSS calculations are conservative for VCSNS Unit 1. Plant specific thermal/hydraulic analyses will use no less than 2958 MWt which corresponds to 1.02 times the plant's licensed power level. Power level assumptions within the 3-loop WOAP analyses (i.e., 3010 MWt) are bounding for VCSNS Unit 1.

Note that outside of emergency feedwater demands, decay heat differences with regard to the ELAP transient in general are considered a second/third order effect. That is, the impact on the transient time lines should not vary significantly if differences in burn-up, core power, etc.,

exist with regard to the reference cases. This is mainly because RCS mass, injected accumulator mass and RCP seal leakage rate are the significant factors in governing the time to when reflux cooling is obtained.

Cl Confirm the key initial The generic analyses provided in WCAP-1 7602-P comply 3.2.1.4.A plant parameters and with the general criteria and assumptions outlined for use assumptions from in Section 3.2 of NEI 12-06 for development of baseline WCAP-1 7601-P used coping capabilities. A list of key initial parameters and in the forthcoming assumptions used in WCAP-1 7601-P for the three loop plant-specific generic plant analyses along with corresponding plant analyses (discussed specific values for VCSNS Unit 1 is provided on the e-in Section 3.2.1.1 of portal. Overall, the initial conditions assumed within the this report) are generic analyses are representative for VCSNS. It is consistent with the noted:

apprpriae vaues1)

The initial power level bounds that of VCSNS Unit from NEI 12-06, 1 when the normal Final Safety Analysis Report Section 3.2, justify (FSAR) Chapter 15 power level uncertainty of 2%

deviations, and is included.

validate they are appropriate for

2) The PORV capacity of VCSNS Unit 1 is simulating the ELAP substantially larger, thus ensuring the ability to transient.

achieve the cooldown rates simulated.

3) Although the liquid mass within the RCS is

Document Control Desk Enclosure RC-I16-0004 CR-I12-01078 Page 13 of 31 ISE Item Item esript.io

Response

essentially the same, the Delta-75 SGs at VCSNS Unit 1 provide for approximately 20% more liquid mass that will have a short term beneficial effect on primary to secondary heat transfer.

4) The VCSNS Unit 1 accumulator liquid volume and gas pressure bound the generic plant values (i.e.,

are higher), thus assuring their effectiveness when utilized.

As outlined in the VCSNS Unit 10QIP, the results of WCAP-1 7601-P are applied selectively in recognition that VCSNS Unit 1 uses Flowserve N-9000 low leakage, shutdown seals, which greatly extends the core cooling coping time. It is anticipated that the Flowserve N-9000 seal package will have an expected leak rate of 2.5 gpm per RCP at normal operating pressure, which is expected for a relatively short duration (between 2 and 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months after ELAP), with a long term maximum of 1 gpm per RCP, beginning at approximately 4-6 hours after ELAP.

VCSNS's plant specific analyses also complies with the general criteria and assumptions outlined for use in Section 3.2 of NEl 12-06 while accounting for the impact of planned plant modifications and plant specific FLEX response procedures.

CI Confirm plans to VCSNS Unit 1 complies with the NEI Shutdown/Refueling 3.2.1.7.A conform to the NEI Modes position paper. Compliance requires the following:

position paper 1)Consideration of the need to maintain FLEX endorsed by the NRC 1

("ShudownRefulingequipment necessary to support shutdown risk (Mhtown/Refueling processes and procedures readily available.

Modes"i(ADAMS Accession14 No.

2) Consideration of the need for deployment (or pre-NRCletteAr4 byte deployment) to support maintaining or restoring the key safety functions in the event of a loss of September 30, 2013shtonclig (ADAMS Accession No. ML13267A382))

3) Pre-deployment of FLEX equipment in locations or propose another ta ol ucl eoeiacsil sarsl straegyfor hutownof loss of decay heat removal from an ELAP and refueling modes.

eet CI Core Sub-Criticality -

VCSNS Unit I design calculation, DC00080-003, Revision 3.2.1.8.A Confirm plans to apply 3, was completed to specifically address these items.

the generic resolution Each of the three N RC clarifications in ML13276A183 has

Document Control Desk Enclosure RC-1 6-0004 CR-12-01 078 Page 14 of 31 ISE Item [Item Description jResponse for boron mixing under natural circulation conditions potentially involving two-phase flow, in accordance with the Pressurized-Water Reactor Owners Group (PWROG) position paper, dated August 15, 2013 (ADAMS Accession No. ML13235A135 (non-public for proprietary reasons)),

and subject to the conditions provided in the NRC endorsement letter dated January 8, 2014 (ADAMS Accession No. ML13276A183).

Alternatively, justify the boric acid mixing assumptions that will ensure adequate shutdown margin exists through all 3 phases of an ELAP event.

been addressed. Reactor makeup must start within 20 hours2.314815e-4 days 0.00556 hours 3.306878e-5 weeks 7.61e-6 months of a beyond-design-basis external event (BDBEE) to meet the boron mixing criteria.

Cl 3.2.1.9.A Confirm the analysis to substantiate expected flow performance for mitigation strategies in the use of pumps, hoses, pipe runs, and connection hardware to facilitate the implementation of coping strategies.

Additional review is necessary to verify adequate supporting VCSNS Unit 1 design calculations, DC00080-007 and DC00080-009, have been completed to analyze expected flow performance for FLEX mitigation strategies. The calculations confirm that the expected flows are as expected and are adequate to implement the FLEX mitigating strategies as outlined in the FLEX Integrated Plan and FSP-series procedures.

Document Control Desk Enclosure RC-1 6-0004 CR-I12-01078 Page 15 of 31 analysis has been completed to validate flows and pressures will be achieved and maintained.

CI Spent Fuel Pool Although there are several methods of delivering makeup 3.2.2.A Cooling Strategies -

to the spent fuel pool, the two FLEX UHS pump systems Confirm the unique (FX UHS pump systems) are the minimum set of FLEX storage requirements equipment required for conformance to NEI 12-06 and control of SFP guidance. A single FX UHS pump system is capable of

,FLEX equipment, delivering adequate makeup to the spent fuel pool by applicable portable, delivering flow to a permanent pipe connection to the SFP FLEX equipment cooling system discharge piping or by routing hose from performance criteria the FX UHS Pump system to the SFP operating floor.

to verify conformance Hose routed to the SFP operating floor can either be with NEI 12-06 placed in the pool or connected to a spray header for the guidance, primary and SFP spray option. The hose connection to the SFP alternate connection cooling system permanent pipe is made to seismically points for portable rated, safety related (SR) piping. The SFP cooling system pumps as part of.

connection is located inside the Auxiliary Building (AB), a Phase 2 for robust structure, near the AB roll up door on the 436 foot maintaining SFP elevation, and access to the connection does not require Cooling, and whether entry to the SFP operating floor or any non-robust the connection points buildings.

willbe poteted rom One of the FX UHS pump systems is stored in the FSB*.

extree extrnal while the other is stored in the ERB. A track vehicle with a evets uchtha at crane is stored in both buildings to facilitate deployment~of' leas on conecion the FX UHS pump system. Both the FSB and ERB are is aailaledesigned and constructed to ASCE 7-10 and are physically separated as discussed in the response to Cl 3.1.3.1.A.

CI Confirm the The evaluations, including mitigation plans, for plant 3.2.4.2.A necessary analyses to locations involved in the FLEX strategies are provided in substantiate expected TR00080-003, "FLEX Equipment Ventilation and room and area Habitability Assessment."

temperature extremes, and the effectiveness of any temperature mitigation plans in conformance with NEI 12-06, Section 3.2.2,

_________ Guideline 10,

Document Control Desk Enclosure RC-1 6-0004 CR-I12-01078 Page 16 of 31 ISE Item Item Description

,Response regardling equipment ventilation.

Cl 3.2.4.3.A Confirm analyses to address the potential for boric acid precipitation in existing equipment and lines that might result from loss of normal building heating provisions in the event of an ELAP, and, if required, develop mitigation plans to address this concern.

The VCSNS Unit 10OIP discusses two diverse sources of boric acid that can be used for injection into the RCS in Phase 2. The RWST and the BATs are the on-site sources for borated water which are available for use as part of FLEX mitigating strategies.

For the BATs, the plant technical specifications (limiting condition for operation (LCO) 3.1.2.6) require the BATs contain a solution of between 7000 ppm and 7700 ppm boron. The technical specifications also require a minimum solution temperature of 65°F be maintained, in order to prevent precipitation of the boron at lower temperatures.

The following methodology identifies the temperatures at which boric acid precipitation occurs:

Convert boron concentration to weight percent of boron:

Boron ppmBAT

= 7700 BoronppmBAT.(5.719510- 4) = 4.404 wt %

From WCAP-1 570, the following boric acid solubility limits are provided:

Solubility of H3BO3 Temperature (gram H3BO3 per 100

(°F) gram saturated solution) 2.7 32 3.14 41 3.51 50 4.17 59 4.65 68 Linear interpolating gives the following temperature associated with solubility limit for 4.4% weight boric acid:

Document Control Desk Enclosure RC-1 6-0004 CR-12-01 078 Page 17 of 31 ISE Itemf Item Description {Response x :=4.17 x2 :=4.404 x3 :=4.65 T1:=59°F T 3.-

68 °F (x2 - xl)(T-T)

T:=

(x3 - Xl)

+ T1=63.387°F For the RWST, Technical Specifications (LCO 3.1.2.6) require the RWST contain a minimum boron concentration of 2300 ppm boron and a minimum solution temperature of 40°F. The temperature at which boron precipitates in the RWST is less than freezing temperature.

FSP-8.0, "Alternate RCS Boration," guides the operators in selecting a boration water source. BAT A and BAT B are listed as preferred, while the RWST source is an alternate. The BATs are SR, seismically designed tanks located in an enclosed room that can be accessed on the AB 463 foot elevation. The BAT Room (63-06) is surrounded with concrete walls and experiences a loss of ventilation during an ELAP. Temperature in the BAT is normally 90°F (see chemical and volume control system design basis document, Table 4.23-1) and room temperature is supported by two unit heaters (XHC0032A and XHC0032B). During an ELAP tank temperature is no longer maintained by pumped recirculation, and power is lost to the area space heaters. However, significant thermal inertia exists in the system such that temperatures would not be expected to drop to 64°F before RCS boration must be completed (approximately 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months ). Additionally, the piping run from the BAT to the FLEX connection at XVA09759 is a short run that drops to the AB 436 foot elevation and is not exposed to outside air during the ELAP. For these reasons, the step in Emerqencv Operatin~q Procedure (EOP)-6.0/ECA-0.0, V

d I

V I

Document Control Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 18 of 31 ISE Item ] Item Description

Response

"Loss of All ESE AC Power," to dilute the BAT to 50% of the technical specification boron concentration is not necessary to implement RCS boration (although the step will remain in EOP-6.0).

The alternate boration source, the RWST, is located outdoors on the west side of the AB. The tank and associated piping/instrumentation is SR and robust for seismic events, but is not considered robust for the high wind hazard (see FSAR, Section 3.5.1.4). The RWST and associated outdoor piping is protected from cold weather via heat tracing. For an ELAP caused by an ice storm, heat tracing can be restored within a few hours with the use of the FLEX combustion turbine generators (CTGs). It is possible that the instrument lines may freeze before the CTGs are available, but the restoration of heat tracing would thaw the lines. The tank and associated 10 inch suction line have considerable thermal inertia and are unlikely to experience icing before the heat tracing can be reenergized.

Document Control Desk Enclosure RC-16-0004 CR-I12-01078 Page 19 of 31 ISEItm I temDescrito j.R.sponse Cl 3.2.4.4.A Complete the analyses regarding the need for additional lighting and, if required, develop mitigation plans.

Further review of the lighting provisions is necessary.

Essential lighting may be restored once an AC ESF bus becomes energized by FLEX equipment. Essential lighting is provided for access in the Turbine Building, AB, DG Building, Water Treatment Building, Intermediate Building, and Control Building.

Control Room - Appendix R lighting in the Control Room is seismically mounted, so the Appendix R lighting is adequate to light the Control Room for eight hours following the BDBEE.

The FLEX DC load shed strategy requires operators to open the breakers to the essential lighting panels (Lighting Panels DPN8014A and DPN8015B) as part of the load shedding to extend ESF battery life during the ELAP if the DC battery chargers are not re-energized by FLEX generators. The DC load stripping initiates at three hours and must be completed at four hours after the onset of the FLAP. Lighting will either be stored on the 463 foot elevation of the Control Building or delivered to the Control Building from one of the FLEX equipment storage locations. This portable lighting will illuminate the Control Room once power is available from FLEX Generators.

Technical Support Center (TSC) - Currently, the TSC is located in the Control Building adjacent to the Control Room. If normal lighting in the TSC is unavailable, area-wide lighting will be deployed as described above for the 463 foot elevation of the Control Building. The primary.

TSC assembly location will eventually be in the Nuclear Operations Building. This location is equipped with a backup diesel generator. If the Nuclear Operations Building is affected by BDBEE, TSC staff can assemble in a backup TSC location on the 463 foot elevation in the Control Building.

Engineering Change Request (ECR) 51006 installed electrical connections between a power pack stored on the Control Building 463 foot elevation and the 300 kW diesel generators in the Electrical Building (EB) and Auxiliary Electrical Building (AEB). The power pack can be used to energize portable LED lights that have been procured as a part of ECR 51006. These lights can be used to illuminate the TSC.

Flashlights are part of the standard gear for operators and can be used for local operations outside of the Control Room. Additionally. Appendix R li~Qhtin~Q will be available

Document Control Desk Enclosure RC-1 6-0004 CR-I 2-01078 Page 20 of 31 ISE Item ItmDsrpion I

Response

for the initial eight hours in certain locations throughout the plant.

Debris Clearing Equipment and Other Vehicles: The Caterpillar 938K Wheel Loader is outfitted with front and rear halogen work lights for night debris removal activities.

The two Prinoth Panther T8 track vehicles are equipped with both dual rear halogen lights and work area flood lights. The Kubota vehicles stored in the ERB are also equipped with headlights and are outfitted with additional 4500 and 10,000 lumen LED lights used to assist plant personnel with FLEX activities.

Deployment and Operation of Phase 2 Equipment:. Major FLEX equipment (pumps and large generators) has self-contained lighting that is adequate for night-time staging and operation. Additionally, four lighting towers are available to assist plant personnel if necessary.

Generally, small portable lighting (e.g., flashlights, lanterns) is sufficient to make connections to plant equipment. The lighting towers provide additional assurance that adequate lighting will be available to perform FLEX related tasks.

National SAFER Response Center Equipment (Phase 3 Equipment): The Phase 3 delivery of equipment from the National SAFER Response Center (NSRC) includes three 30 foot tall light towers to support the unloading and staging of the SAFER FLEX equipment. These portable light towers provide light coverage for 5-7 acres. Each tower has four lamps powered by a 30 kW diesel generator.

Document Control Desk Enclosure RC-l16-0004 CR-I12-01 078 Page 21 of 31 ISE Item Item Description

Response

CI Communication -

The upgrades to the site communications strategies 3.2.4.4.B Confirm that upgrades identified in SCE&G Letter RC-12-0082 (ML12164A380),

to the site's dated June 8, 2012, SCE&G Letter RC-12-0083, dated communications October 30, 2012, and SCE&G Letter RC-13-0023 dated systems have been February 21, 2013, have been completed. The completion completed in of the upgrades has been documented in condition report accordance with the CR-14-0091 1 action 19.

licensee's communications Assessment and as evaluated by the NRC staff (ADAMS Accession Nos. ML12307A032 and ML13057A111).

Cl Personnel Habitability The evaluations for plant locations involved in the FLEX 3.2.4.6.A

- Elevated strategies are provided in TR00080-003, "FLEX Temperature-Equipment Ventilation and Habitability Assessment."

Complete room Habitability concerns are addressed in the referenced habitability analyses technical report.

and any modification or mitigation plan changes needed as part of the implemented Integrated Plan for conformance to NEI 12-06.

CI Electrical Power VCSNS Unit 1 design calculation, DC08260-001, has 3.2.4.8.A Sources!/Isolations been developed for sizing the FLEX generators, and Interactions -

supporting the use of two Turbine Marine 1250KVA Confirm that the (1 MW) CTGs operating in parallel at 7200VAC connected selected diesel to either/both XSW1 DA/XSWI1DB busses. These CTGs generators are will support two SR Battery Chargers (Phase 1 item), one appropriately sized.

Motor Driven Emergency Feedwater Pump (Phase 2 item) and one reactor building cooling unit (RBCU) fan (Phase

3) in slow speed.

An alternative method of providing battery charging power is through the use of the 480VAC (300kW) DGs (Calc DC08260-002) located in the EB (auto-starts on loss of normal power) and AEB (auto-starts if the EB DG fails)

_________buildings.

Within the EB there are two 200A/135VDC

Document Control Desk Enclosure RC-1 6-0004 CR-I12-01078 Page 22 of 31 ISE Item Item Description

Response

(58kVA/52kW) battery chargers with dedicated and staged separate feeds to quick connectors to DPN1HA2 and DPN1 HB2 panels in the Relay Room. The capacity of the EB/AEB DGs exceeds the load imposed by the two backup FLEX battery chargers.

A third alternative for battery charging is the use of onsite 100~kVA/80kW mobile generators. Electrical procedure EMP-100.016, "Temporary Power from 80kW BDMG to XBC1A, XBC1IB, or XBC1A/1B Swing Battery Chargers,"

directs the use of pre-built cabling and breaker boxes to supply power to two of the SR battery chargers. The procedure calls for slowly loading the battery chargers while in communication with an operator/electrician at the diesel generator to preclude overloading the generator.

The normal combined full loading of two of the station SR battery chargers is 86.6kVA (78kW) which is near the full kW load of any of the DG units, but does not exceed the capability of the 100% full rated units.

There are 120/240VAC (5kW) single phase DGs with fan units designed to provide ventilation within the Turbine Building/Control Building/Intermediate Building/AB areas.

Each DG has been endurance tested with associated cabling to supply its respective fan loads (FSP-20.1).

The Phase 3 strategy for maintaining core cooling and battery charging is a continuation of the Phase 2 method.

The 4kV and 480V NSRC generators are considered backup equipment and are not required to support the key safety functions during Phase 3 of the coping response.

The two 1MW 4kV NSRC generators are capable of supplying the Phase 2 loads documented in DC08260-001, since the losses associated with the 4kV to 7.2 kV transformer and associated cabling are considered insignificant compared to the available margin documented in DC08260-001. The sizing of the 1MW 480V NSRC generator is adequate given the excess capacity over the generators that would be replaced (1 MW compared to 300 kW and 80 kW 480V generators).

Document Control Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 23 of 3l ISE Item Item Description

Response

The table below provides the Phase 2 electrical loading and available margin.

Electrical Loads Power Power (kW)

RBCU Fan (MFN97A/B) 75 HP 56 MDEFW Pump (XPP21A/B) 600 HP 447 Battery Charger (XBC1A) 50 kVA 40 Battery Charger (XBCIB) 50 kVA 40 Total Required FLEX Loads 583 Available Margin 1417 Phase 3 Electrical Loading and Available Margin Electrical Loads Power Power (kW)

RBCU Fan (MFN97AIB) 75 HP 56 MDEFW Pump (XPP21A/B) 600 HP 447 Battery Charger (XBC 1A) 50 kVA 40 Battery Charger (XBC1 B) 50 kVA 40 Total Required FLEX Loads 583 Available Margin 1417 Cl Load Reduction to Those ESF I25VDC and Vital I20VAC loads that are 3.2.4.1 0.A Conserve DC Power -

stripped either do not change state (loss of power - fail as-Confirm which is) or the change of state is dramatically evident (power components change removed from control board alarms - no lights, power state when loads are removed from emergency DC lighting - no light, power shed and the actions removed from DG control panel - no lights/control, etc).

needed to mitigate Operations will use flashlights/headlamps (supply.

resultant hazards (for maintained in shift manager's office area) to observe example, allowing instruments and operate the limited controls which will hydrogen release remain operational as long as the ESF batteries remain from the main

>105VDC (depending on which alternative of generator, disabling DC08320-019 is selected, from 15 to 100 hours0.00116 days 0.0278 hours 1.653439e-4 weeks 3.805e-5 months ). The credited equipment other ESF equipment will be aligned per via interlocks, etc.)

EOP-6.0/ECA-0.0, "Loss of All ESF AC Power," and has following FSG been analyzed for state change or reconfiguration per the development.

FSPs.

Breakers/Switches that must be opened are listed in FSP-4.0, "ELAP DC Bus Load Shed Management," (DC load shed based on Alternative 4 of DC08320-019). A review of this list has not identified any items that will hamper operations during the event, result in changing position or create a safety hazard. All SR 120VAC and

Document Controi Desk Enclosure RC-1 6-0004 CR-I12-01078 Page 24 of 31 ISE Item Item Description

Response

125VDC equipment de-energized during implementation of FSP-4.0 is assumed to fail to its de-energized ESE position (i.e. PORV's fail closed, letdown fails closed, switchgear fails as-is, relays fail to de-energized state, etc.). The 125VDC-powered seal oil pump for the main generator is powered from Non-Nuclear Safety (NNS) batteries and is not impacted by FLEX Station Blackout!

Extended Loss of AC Power (SBO/ELAP) load shedding procedures (no failure of this equipment is assumed beyond the existing license actions of EOP6.0/ECA-0.0).

Support items such as radios and satellite phones have batteries that support usage for a minimum of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months with no operations action.

SR equipment that is left in service include controls for EFW valves, RVLIS, one pressurizer PORV, SG PORVs (assuming air is available), source range nuclear instruments, RCS pressure and temperature, pressurizer level, SG level and flow indicators (in and out), CST Level, SFP level and temperature.

The load shedding that is being considered (as described in FSP-4.0) only impacts the ESE 125VDC and Vital I20VAC loads. The power supply for non-essential equipment (i.e. generator hydrogen control) is not affected by FLEX SBO/ELAP load stripping in any way. The power to non-essential equipment will either be lost immediately upon entering the ELAP or once the non-essential uninterruptible power supply/batteries go below their operating threshold for voltage (102 to 104VDC in 1-2 hours). The Appendix R emergency battery lights throughout the plant will come-on and operate up to the exhaustion of their battery (approximately 8-12 hours).

Operations procedures (EOP 6.0/ECA-0.0) have always existed for the emergency release of hydrogen from the main generator and securing associated DC powered motors in the event of a loss of power to the balance of plant busses (limited battery availability). All turbine/generator X-Train DC (NNS battery XBA-1X) powered motors are secured per EOP-6.0/ECA-0.0 attachments based on meeting industry established standards such as pressure and/or machine rotation prior to shut down.

CI

{Confirm conformance In the development of the ultimate battery life design 3.2.4.10.B to the generic calculation, DC08320-019, the most conservative

Document Control Desk Enclosure RC-1 6-0004 CR-I12-010O78 Page 25 of 31

ISE Item [Item Description~

Response

approach in the NEI position paper on battery life ("Battery Life Issue" (ADAMS Accession No. ML13241A186 (position paper) and ML13241A188 (NRC endorsement letter)),

as endorsed by the NRC, or provide an acceptable alternative.

assumptions were made with respect to extended battery life, consistent with the NEI position paper. The original equipment manufacturer graph displaying Ampere-Hours per positive plate (Attachment 7 of DC08320-01 9, Revision 1) was used along with the most restrictive age and temperature penalties to determine estimated battery life based on load. Four cases are considered in the referenced calculation. The FLEX strategies and procedures are based on Case 4. Case 4 demonstrates that core parameters can be monitored/controlled with the station SR batteries as the sole power source for 15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months if the prescribed load shed is accomplished within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . Case 4 mentions assumed entry conditions (page 17 of 19) including restoration of off-site power or repair of DGs, and availability of support personnel within 15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months . These assumptions made in the calculation are not applicable to the FLEX strategies. FLEX equipment must provide charging power to the SR station batteries within 15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months to preserve battery function.

VCSNS Unit 1 confirms that the FLEX strategy station battery run-time was calculated in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 485 methodology using manufacturer discharge test data applicable to the licensee's FLEX strategy as outlined in the NEI white paper on extended battery duty cycles. The detailed licensee calculations, supporting vendor discharge test data, FLEX strategy battery load profile, and other inputs/initial conditions required by IEEE-485.

are available on the licensee's web portal for documents and calculations. The time margin between the calculated station battery run-time for the least restrictive FLEX strategy and the expected deployment time for FLEX equipment to supply the DC loads is at a minimum 15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months .

Cl Off-Site Resources-The station has made arrangements with the Strategic 3.4.A Confirm the licensee's Alliance for FLEX Emergency Response (SAFER) to arrangement for off-provide Phase 3 equipment to VCSNS Unit 1 upon site resources request. The required actions and interfaces necessary to addresses the obtain, deploy and operate these resources and guidance of equipment are described in the SAFER Response Plan Guidelines 2 through for VCSNS Unit 1, as endorsed by the NRC letter dated 10 in NEI 12-06, September 26, 2014. SAFER conforms to the guidance Section 12.2.

described in Guidelines 2 through 10 of NEI 12-06, Section 12.2. The NEI white paper titled, "National

Document Control Desk Enclosure RC-16-0004 CR-12-01 078 Page 26 of 31 Item De'scriptioni Response..

SAFER Response Centers," provides additional details specific to the requirements of this NEI.12-06 section.

The NRC audit team concluded the onsite portion of the Mitigati~ng Strategies Audit on July 17, 2015. The following table provides the FLEX related open items from the NRC Audit Report (Reference 11). These items are considered complete pending NRC closure.

.Audit Report.

Item DeScription

Response

t, *Item ISE Cl Confirm the acceptability of the The VCSNS Unit 1 response for ISE 3.2.1.2.A use of the non-Westinghouse Cl 3.2.1.2.A is provided in the table above.

RCP seals in the Westinghouse RCPs; provide justification for the RCP seal leakage rates for use in the ELAP analysis; and confirm the acceptability of 0-ring performance under high temperature conditions expected

___________during an ELAP event.

AQ 12 Provide the value of the The leak-off for each RCP seal affects the maximum leak-off for each RCP RCS inventory in ELAP analysis.

seal in gpm assumed in the Flowserve's paper, "White Paper on the ELAP analysis.

Response of the N-Seal Reactor Coolant.

Pump (RCP) Seal Package to Extended Loss of All Power (FLAP)," Revision-A, documents the bounding leakage value for each RCP seal during plant specific ELAP scenarios. For VCSNS Unit 1, according to the white paper, the bounding flow rate is 2.5 gpm per pump in the first 133.2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months before the potential elastomer failure and maximum 6.73 gpm per pump after the elastomer failure. This bounding 2.5 gpm of leakage per pump is incorporated in TR00080-006, Revision 0, to calculate the time to reflux cooling (39.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months ) and time to core uncover (80.7 hours8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months ). Note that this 2.5 gpm of leakage is the CBO flow. As cooldown and depressurization is part of the ELAP strategies, the CBO flow will decrease with the square root of the pressure differential across the seal after

Document Control Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 27 of 31

... Item. Description.

Response.

depressurization. Therefore, using the bo~unding 2.5 gpm of leakage is conservative.

SE Item 16' Alternate Emergency Feedwater (EFW) Strategy - Because the Condensate Storage Tank (CST) is susceptible to damage from high winds and missiles, the licensee is developing an Alternate EFW Strategy for loss of CST. The NRC staff requests that the licensee make available for audit.the strategy for providing emergency feedwater to the steam generators in the event of a loss of the CST.

Several facets of the strategy will have to be addressed including, but not limited to, hydraulic analysis, clogging considerations for the FLEX pump, timing of actions, and pre-staging of equipment.

ECR 51003B is installing an alternative EFW suction source by establishing a new connection to the Service Water Pump discharge crosstie header, downstream of XVB031 16C, in the Service Water Pump House (SWPH) at floor elevation 425 ft.

The purpose of this system will be to deliver water from the Service Water Pond to the suction of an EFW pump via the existing piping and isolation valves provided for backup supply of Service Water (SW) to EFW. The system will provide 500 gpm at 100 foot net positive suction head to the suction of either the TDEFP or a Motor Driven Emergency Feedwater Pump. All mechanical equipment and connections are located within the Seismic Category 1 SWPH structure.

This system is also designed to be placed in service rapidly, within the time to dry out.

a Steam Generator, assuming the TDEFP must be secured at the onset of the event, due to the loss of suction. The estimated time to place the system in service is within 30 minutes from direction by the Control Room. The estimated time the Control Room will recognize the need is within 15 minutes of SBO (independent of ELAP declaration) and would be directed from EOP 6/ECA-0.0 before overall entry into FSPs is directed. Confirmation of the qualitative estimate will be documented in SCE&G Technical Report TR00080-007, "VCS Unit 1 FLEX Validation Document," 5 - Validation Plan VCS1-FLEX-24, Establish Alternate EFW Suction Source - which currently identifies the tasks, subtasks and other considerations that are critical to the validation process.

Document Controi Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 28 of 31 AuItRepor {

I..

tem Description..

Response.

This validation will take place after pump installation and prior to final system acceptance. Timing confirmation or updates, if any, and margins will be documented accordingly.

The ECR is installing a permanent 4" stub out to the SW discharge crosstie header

("C" train) to provide a discharge.

connection for the permanently installed FX Alternate EFW Suction Pumps (XPP0248A and XPP0248B) where flow can be directed into the "A" or "B" train of Service Water as necessary. The pump discharge will be connected to the Service Water discharge header via a temporary hose. A permanent 6" suction line will be installed to allow XPP0248A or B to draw suction from the C SW Pump Intake Bay.

The permanent piping, valves, and connections are seismically qualified and located within the protective structure of the SWPH. The alternate EFW Pump suction line does not provide a strainer function in this configuration. The suction is downstream of the SW intake traveling screens and no significant debris is expected. If pump clogging does occur',

the alternate (redundant) pump can be quickly connected and used as Alternate SW to EFW supply. Also, the SW is chemically treated to reduce fouling and all permanent suction piping is stainless steel.

The suction line will be connected with a hose to the 4" pump suction connection on XPP0248A or XPP0248B. The hoses will be stored with the Alternate EFW suCtion pumps.

ECR 51012 is installing the FLEX Alternate EFW Suction Source Diesel Generator Building (FDG Building) that will house two 80 kW diesel electric generators (XEG0140 and XEG0141) necessary to power the FX Alternate EFW

Document Control Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 29 of 31 Audit Report Item Description tResponse Item Suction Pumps. The new EDO Building shall be a nominal 500 square foot interior floor plan with a minimum two feet thick reinforced concrete walls and roof. The FDG Building will be located southeast of the Unit 1 Power Block, just south of the FLEX Storage Building (FSB) outside of the Unit 1 Protected Area, but within the Owner Controlled Area. The structure will be designed to meet the minimum design load requirements of the 2012 International Building Code and ASCE 7-10 as specified in NEI 12-06 for FLEX structures. This includes wind, seismic, snow, flooding, and live loads for Jenkinsville, South Carolina. The structure and all enclosed equipment will meet VC Summer design requirements for tornado missile protection.

NEI 12-06 specifies that the FLEX fluid connections for Core and SFP cooling functions are expected to have a primary and an alternate connection or delivery point. Both the primary and alternate connection points do not need to be available for all applicable hazards, but the location of the connection points should provide reasonable assurance of at least one connection being available. However, if separate strategies are employed, then the two strategies do not each need a primary and alternate connection point as long as the connection points for the two strategies are separate.

A single connection point, specific to the high winds hazard specific method of supplying TDEFW suction, is acceptable for the following reasons.

1. The connection point inside the Service Water Pump House is protected from the design basis tornado wind loads and associated

Document Control Desk Enclosure RC-1 6-0004 CR-I12-01078 Page 30 of 31 A-udi

"..iReport Ite m Descriptio ni".

........R-esponse Item..

_ r, missiles and is only credited for this hazard specific strategy.

2. The connection point on the Service Water Pump discharge header is able to feed either train of Service Water.

3. Availability of the Alternate EFW Strategy components and connections is managed in VCS-ERP-0012, "BDB Equipment Availability Monitoring." In accordance with NEI 12-06, Section 11.5, if the Alternate EFW System components or connections become unavailable such that the Alternate EFW capability (N) is not maintained, VCS personnel will initiate actions within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to restore the Alternate EFW capability (N) and implement compensatory measures within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

Supporting documents, available on the e_-

portal, include the engineering change request, updated SOE, and hydraulic calculation.

7 Potential Draft Safety Evaluation Impacts No potential impacts to the Draft Safety Evaluation have been identified.

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

1. SCE&G Letter, Virgil C. Summer, Unit 1, Overall Integrated Plan 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 Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for

Document Control Desk Enclosure RC-1 6-0004 CR-i12-01078 Page 31 of 31 Beyond-Design-Basis External Events, dated March 12, 2012, ADAMS Accession Number ML12054A735

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 (Order Number 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. 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

6.

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

7. SCE&G Letter, Virgil C. Summer, Unit 1, 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 049), dated August 24, 2015, ADAMS Accession Number ML15239A750

8.

SCE&G Letter, Request for Schedule Relaxation from NRC Order EA-12-049, "Order Modifying Licenses With Regard To Requirements For Mitigation Strategies For Beyond-Design-Basis External Events," dated August 13, 2015, ADAMS Accession Number ML15231A025

9. NRC Letter, Virgil C. Summer Nuclear Station, Unit 1 - Relaxation of the Schedule Requirements of Order EA-12-049 "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated October 4, 2015, ADAMS Accession Number ML15243A450

10. 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

11. NRC letter, Virgil C. Summer Nuclear Station, Unit 1 - Report for the Onsite Audit Regarding Implementation of Mitigating Strategies and Reliable Spent Fuel Instrumentation Related to Orders EA-12-049 and EA-12-051, dated September 16, 2015, ADAMS Accession Number ML15253A721