CNL-14-033, Second Six-Month Status Report and Revised Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses Re Requirements for Mitigation Strategies for Beyond-Design-Basis External Events

Second Six-Month Status Report and Revised Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses Re Requirements for Mitigation Strategies for Beyond-Design-Basis External Events

ML14064A295
Person / Time
Site:	Sequoyah
Issue date:	03/05/2014
From:	James Shea Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML14064A293	List: CNL-14-033, Second Six-Month Status Report and Revised Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses Re Requirements for Mitigation Strategies for Beyond-Design-Basis External Events
References
CNL-14-033, EA-12-049
Download: ML14064A295 (85)

Text

L44 140228 007 Enclosure 1 Attachment 3 is to be withheld from public disclosure under 10 CFR 2.390.

When separated from this submittal, this letter is decontrolled.

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-14-033 February 28, 2014 10 CFR 2.202 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Units 1 and 2 Facility Operating License Nos. DPR-77 and DPR-78 NRC Docket Nos. 50-327 and 50-328

Subject:

Second Six-Month Status Report and Revised Overall Integrated Plan in Response to the 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) for Sequoyah Nuclear Plant

References:

1. Letter from TVA to NRC, Tennessee Valley Authority (TVA) - Overall Integrated Plan in Response to the 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) for Seqoyah Nuclear Plant, dated February 28, 2013 (ML13063A183)

2. Letter from TVA to NRC, 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-12-049) for Sequoyah Nuclear Plant, dated August 28, 2013 (ML13247A286)

On February 28, 2013, the Tennessee Valley Authority (TVA) submitted an Overall Integrated Plan (OIP) in response to the March 12, 2012, Commission Order modifying licenses with regards to requirements for mitigation strategies for beyond-design-basis external events, Order number EA-12-049, for the Sequoyah Nuclear Plant (SQN), Units 1 and 2 (Reference 1). On August 28, 2013, TVA provided the first six-month status report to the OIP (Reference 2).

Enclosure 1 Attachment 3 is to be withheld from public disclosure under 10 CFR 2.390.

When separated from this submittal, this letter is decontrolled.

U.S. Nuclear Regulatory Commission Page 2 February 28, 2014 The OIP submitted in Reference 1 employed a strategy using reactor coolant pump (RCP) low leakage seals. TVA has revised its strategy to u~e the existing conventional RCP seals.

Therefore, this change in RCP seals requires a revision to the OIP submitted by Reference 1. These changes primarily affect Attachment 1A, "Sequence of Events Timeline, " and required a revision to the reactor coolant inventory calculation supporting this strategy.

These changes were presented and discussed with the Nuclear Regulatory Commission (NRC) through the mitigation strategies audit process.

The purpose of this letter is to provide a revision to the OIP submitted by Reference 1.

Specifically, Enclosure 1 of this letter provides the revised OIP and it replaces the Reference 1 OIP in its entirety. This revision includes the revised RCP seal strategy and supporting changes previously discussed . This OIP employs submersible intermediate and high pressure mitigation strategy (FLEX) pumps located on elevations 669 and 714 of the auxiliary building rather than FLEX pumps located on the auxiliary building roof.

This letter also provides the second six-month status report. In addition to the changes described previously, the Open Items table in the Enclosure has been updated. The milestone target completion dates have also been updated as shown in Attachment 2 of the Enclosure.

It is noted TVA is currently evaluating potential changes to the capacity and storage locations of the current 3 MW FLEX diesels as well as use of the current auxiliary feedwater supply tank. Any changes to the Sequoyah Nuclear Plant mitigation strategies resulting from this review will be provided to the NRC in the third six-month status report.

The conceptual sketches provided in Attachment 3 to the Enclosure are considered to contain information concerning physical protection not otherwise designated as Safeguards Information and are designated "Security Sensitive Information" as defined in 10 CFR 2.390(d)(1). Accordingly, TVA requests that Attachment 3 to the Enclosure be withheld from public disclosure.

There are no new regulatory commitments in this letter. If you have any questions regarding this report, please contact Kevin Casey at (423) 751 -8523.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 28th day of February 2014.

tfully,

~

. Shea Enclosure cc: See Page 3

U.S. Nuclear Regulatory Commission Page 3 February 28, 2014

Enclosure:

Sequoyah Nuclear Plant, Units 1 and 2, FLEX Overall Integrated Plan, Revision 1 cc (Enclosure):

NRR Director - NRC Headquarters NRO Director - NRC Headquarters NRC Regional Administrator - Region II NRR Project Manager - Sequoyah Nuclear Plant NRC Senior Resident Inspector - Sequoyah Nuclear Plant NRR Mitigation Strategies Director - NRC Mitigation Strategies Directorate

ENCLOSURE 1 SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 FLEX OVERALL INTEGRATED PLAN REVISION 1

TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 FLEX OVERALL INTEGRATED PLAN Revision 1 E-1

General Integrated Plan Elements Sequoyah Units 1 and 2 Determine Applicable Extreme External Hazard Ref: NEI 12-06 Section 4.0 -9.0 JLD-ISG-2012-01 Section 1.0 The Sequoyah site has been evaluated and the following applicable hazards have been identified:

• Seismic events

• External flooding

• Severe storms with high winds

• Snow, ice, and extreme cold

• Extreme heat The Sequoyah site has been reviewed against Nuclear Energy Institute (NEI) guidance document NEI 12-06 (Reference 2) and determined that the hazards Flexible and Diverse Coping Mitigation Strategies (FLEX) equipment should be protected from include seismic; external flooding; severe storms with high winds; snow, ice and extreme cold; and extreme high temperatures. Sequoyah has determined the functional threats from each of these hazards and identified FLEX equipment that may be affected. The FLEX storage locations will provide the protection required from these hazards.

Sequoyah is also developing procedures and processes to further address plant strategies for responding to these various hazards.

Seismic:

Per NEI 12-06 (Reference 2), seismic hazards must be considered for all nuclear sites. As a result, the credited FLEX equipment will be assessed based on the current Sequoyah seismic licensing basis to ensure that the equipment remains accessible and available after a beyond-design-basis external event (BDBEE) and that the FLEX equipment does not become a target or source of a seismic interaction from other systems, structures or components. From Reference 4, Section 2.5.2.4, safe shutdown earthquake (SSE) requirements of 0.18 g horizontal and 0.12 g vertical maximum ground accelerations. For an operating basis earthquake (OBE), the maximum horizontal and vertical ground accelerations are 0.09g and 0.06 g, respectively. The FLEX strategies developed for Sequoyah will include documentation ensuring that any storage locations and deployment routes meet the FLEX seismic criteria.

Liquefaction The liquefaction potential of all FLEX deployment routes will be addressed in a future assessment (Open item OI-2)

The types of events evaluated to determine the worst potential flood included (1) probable maximum storm on the total watershed and critical sub-water sheds including seasonal variations and potential consequent dam failures and (2) dam failures in a postulated SSE or OBE with guide specified concurrent flood conditions.

Those safety-related facilities, systems, and equipment located in the containment structure are protected from flooding (Reference 4, Section 2.4.2.2). Only the Reactor Building, Diesel Generator Building (DGB), and Essential Raw Cooling Water Intake Station will remain dry during the flood (Reference 4, Section 2.4A.2.1). Plant cooling requirements, with the exception of the fire protection system which must supply water to the steam generators, will be met by the ERCW system E-2

(Reference 4, Section 2.4A.2.1). All equipment required to maintain the plant safely during the flood is either designed to operate submerged, is located above the maximum flood level, or is otherwise protected (Reference 4, Section 2.4A.2.1).

Specific analysis of Tennessee River flood levels resulting from ocean front surges and tsunamis is not required because of the inland location of the plant (Reference 4, Section 2.4.2.2). Snow melt and ice jam considerations are also unnecessary because of the temperate zone location of the plant (Reference 4, Section 2.4.2.2). Flood waves from landslides into upstream reservoirs required no specific analysis, in part because of the absence of major elevation relief in nearby upstream reservoirs and because the prevailing thin soils offer small slide volume potential compared to the available detention space in reservoirs (Reference 4, Section 2.4.2.2). Seiches pose no flood threats because of the size and configuration of the lake and the elevation difference between normal lake level and plant grade (Reference 4, Section 2.4.5).

Per Reference 4, Section 2.4.2.2, the maximum plant site flood level from any cause is Elevation 719.6 ft. This information has been superseded by Reference 5. The maximum plant site flood level from any cause is elevation 722.0 ft. (still reservoir). This elevation would result from the probable maximum storm. Coincident wind wave activity results in wind waves of up to 4.2 ft. (crest to trough). Run up on the 4:1 slopes approaching the Diesel Generator Building reaches elevation 723.2 ft. Wind wave run up on critical vertical external, unprotected walls including the Emergency Raw Cooling Water (ERCW) Intake Pumping Station, Auxiliary, Control and Shield Buildings is 726.2 ft.

(Reference 5).

In summary, all equipment required to maintain the plant safety during all flooding events including the design basis flood (DBF) is either designed to operate submerged, is located above the maximum flood level, or is otherwise protected. Accordingly, FLEX strategies will be developed for consideration of external flooding hazards. In addition, Sequoyah is also developing procedures and strategies for delivery of offsite FLEX equipment during Phase 3 which considers regional impacts from flooding.

High Wind:

Figures 7-1 and 7-2 from Reference 2 were used for this assessment.

Sequoyah is susceptible to hurricanes as the plant site is within the contour lines shown in Figure 7-1 of Reference 2.

It was determined the Sequoyah site has the potential to experience damaging winds caused by a tornado exceeding 130 mph. Figure 7-2 of Reference 2 indicates a maximum wind speed of 200 mph for Region 1 plants, including Sequoyah. Therefore, high-wind hazards are applicable to the Sequoyah site.

In summary, based on available local data and Figures 7-1 and 7-2 of Reference 2, Sequoyah is susceptible to severe storms with high winds so the hazard is screened in.

Snow, Ice, and Extreme Cold Per the FLEX guidance all sites should consider the temperature ranges and weather conditions for their site in storing and deploying their FLEX equipment. That is, the equipment procured should be suitable for use in the anticipated range of conditions for the site, consistent with normal design practices.

Applicability of snow and extreme cold:

The Sequoyah site is located approximately 7.5 miles northeast of Chattanooga in Hamilton County, Tennessee, on a peninsula on the western shore of Chickamauga Lake at Tennessee River mile 484.4 (Reference 4, Section 1.1). The site is approximately 14 miles west-northwest of Cleveland, Tennessee and approximately 31 miles south-southwest of Watts Bar Nuclear Plant (Reference 4, Section 2.1.1). The approximate site location is given below (Reference 4, Table 2.1.1-1):

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LATITUDE (degrees/minutes): 35°14' N LONGITUDE (degrees/minutes): 85°5' W From Reference 4, Table 2.3.2-16, the mean temperatures in Chattanooga, Tennessee have been in the low 40sF in the winter. The extreme minima temperature recorded was -10°F in the winter (Reference 4, Table 2.3.2-16).

Reference 2 states plants above the 35th parallel should provide the capability to address the hindrances caused by extreme snow and cold. The Sequoyah site is above the 35th parallel; therefore, the FLEX strategies must consider the hindrances caused by extreme snowfall with snow removal equipment, as well as the challenges that extreme cold temperature may present.

Applicability of ice storms:

The Sequoyah site is not a Level 1 or 2 region as defined by Figure 8-2 of Reference 2; therefore, the FLEX strategies must consider the hindrances caused by ice storms.

In summary, based on the available local data and Figures 8-1 and 8-2 of Reference 2, the Sequoyah site does experience significant amounts of snow, ice, and extreme cold temperatures; therefore, the hazard is screened in.

Extreme Heat:

Per Reference 2, all sites must address high temperatures. Virtually every state in the lower 48 contiguous United States has experienced temperatures in excess of 110F. Many states have experienced temperatures in excess of 120F. Sites that should address high temperatures should consider the impacts of these conditions on the FLEX equipment and its deployment. From Reference 4, Table 2.3.2-16, mean temperatures in Chattanooga, Tennessee can reach the upper 80sF in the summer. Extreme maxima temperature recorded was 106°F in the summer (Reference 4, Table 2.3.2-16).

Therefore, for selection of FLEX equipment the Sequoyah site will consider the site maximum expected temperatures in their specification, storage, and deployment requirements, including ensuring adequate ventilation or supplementary cooling, if required.

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Key Site assumptions to Provide key assumptions associated with implementation of FLEX implement NEI 12-06 Strategies:

strategies.

Assumptions are consistent with those detailed in NEI 12-06, Ref: NEI 12-06 Section 3.2.1 Section 3.2.1. Analysis has been performed consistent with the recommendations contained within the Executive Summary of the Pressurized Water Reactor Owners Group (PWROG) Core Cooling Position Paper (Reference 13) and assumptions from that document are incorporated in the plant specific analytical bases.

NEI 12-06 Assumptions The initial plant conditions are assumed to be the following:

• Prior to the event the reactor has been operating at 100 percent rated thermal power for at least 100 days or has just been shut down from such a power history as required by plant procedures in advance of the impending event.

• At the time of the postulated event, the reactor and supporting systems are within normal operating ranges for pressure, temperature, and water level for the appropriate plant condition. All plant equipment is either normally operating or available from the standby state as described in the plant design and licensing basis.

The following initial conditions are to be applied:

• No specific initiating event is used. The initial condition is assumed to be a loss of offsite power (LOOP) at a plant site resulting from an external event that affects the off-site power system either throughout the grid or at the plant with no prospect for recovery of off-site power for an extended period. The LOOP is assumed to affect all units at a plant site.

• All installed sources of emergency on-site ac power and station blackout (SBO) Alternate ac power sources are assumed to be not available and not imminently recoverable.

• Cooling and makeup water inventories contained in systems or structures with designs that are robust with respect to seismic events, floods, and high winds, and associated missiles are available.

• Normal access to the ultimate heat sink (UHS) is lost, but the water inventory in the UHS remains available and robust piping connecting the UHS to plant systems remains intact. The motive force for UHS flow, i.e., pumps, is assumed to be lost with no prospect for recovery.

• Fuel for FLEX equipment stored in structures with designs which are robust with respect to seismic events, floods and high winds and associated missiles, remains available.

• Permanent plant equipment that is contained in structures with designs that are robust with respect to seismic events, floods, and high winds, and associated missiles, are available.

• Other equipment, such as portable ac power sources, portable back up dc power supplies, spare batteries, and equipment for 50.54(hh)(2), may be used provided it is reasonably protected from the applicable external hazards per Sections 5 through 9 and Section 11.3 of NEI 12-06 and has predetermined hookup strategies with appropriate procedures/guidance and the equipment is stored in a relative close vicinity of the site.

• Installed electrical distribution system, including inverters and battery chargers, remain available provided they are protected consistent with current station design.

• No additional events or failures are assumed to occur immediately prior to or during the event, including security events.

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• Reliance on the fire protection system ring header as a water source is acceptable only if the header meets the criteria to be considered robust with respect to seismic events, floods, and high winds, and associated missiles.

The following additional boundary conditions are applied for the reactor transient:

• Following the loss of all ac power, the reactor automatically trips and all rods are inserted.

• The main steam system valves (such as main steam isolation valves, turbine stops, atmospheric dumps, etc.), necessary to maintain decay heat removal functions operate as designed.

• Safety/Relief Valves (S/RVs) or Power Operated Relief Valves (PORVs) initially operate in a normal manner if conditions in the reactor coolant system (RCS) so require. Normal valve reseating is also assumed.

• No independent failures, other than those causing the extended loss of all alternating current (ac) power (ELAP) / loss of the ultimate heat sink (LUHS) event, are assumed to occur in the course of the transient.

Sources of expected pressurized water reactor (PWR) reactor coolant inventory loss include:

• Normal system leakage

• Losses from letdown unless automatically isolated or until isolation is procedurally directed

• Losses due to reactor coolant pump (RCP) seal leakage (rate is dependent on the RCP seal design)

The initial spent fuel pool (SFP) conditions are:

• All boundaries of the SFP are intact, including the liner, gates, transfer canals, etc.

• Although sloshing may occur during a seismic event, the initial loss of SFP inventory does not preclude access to the refueling deck around the pool.

• SFP cooling system is intact, including attached piping.

• SFP heat load assumes the maximum design basis heat load for the site.

Containment Isolation Valves:

• It is assumed that the containment isolation actions delineated in current SBO coping capabilities is sufficient.

Assumptions Specific to Sequoyah Site A1. The Auxiliary Feedwater Supply Tank (AFWST) and associated piping are seismically qualified or hardened against missiles and tornados. Sequoyahs AFWST will be qualified to be robust with respect to high winds and seismic events.

A2. Sequoyah Unit 1 is a mirror image of Unit 2, with only minor differences existing between plants. For this reason, any sections or sketches which are only shown for a single unit would be directly analogous to the other unit.

A3. The design hardened connections added for the purpose of FLEX are protected against external events or are established at multiple and diverse locations.

A4. Flood and seismic re-evaluations pursuant to the Title 10 of the Code of Federal Regulations (10 CFR) 50.54(f) letter of March 12, 2012 are not completed and therefore not assumed in this submittal. As the re-evaluations are completed, appropriate issues will be entered into the corrective action program.

A5. To support time sensitive FLEX actions, it is assumed adequate staffing levels will be E-6

available. Required staffing levels will be determined consistent with guidance contained in NEI 12-06 for each of the site specific FLEX strategies. Assumed available staffing levels will be determined consistent with NEI 12-01, as described below:

A. Post event time: 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> - No site access. This duration reflects the time necessary to clear roadway obstructions, use different travel routes, mobilize alternate transportation capabilities (e.g., private resource providers or public sector support), etc.

B. Post event time: 6 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> - Limited site access. Individuals may access the site by walking, personal vehicle or via alternate transportation capabilities (e.g., private resource providers or public sector support).

C. Post event time: 24+ hours - Improved site access. Site access is restored to a near-normal status and/or augmented transportation resources are available to deliver equipment, supplies and large numbers of personnel.

Staffing levels will be assessed to confirm this assumption, or adjustments will be made to plant staffing or FLEX design to meet this requirement.

A6. Sequoyah will design one new storage location to protect portable FLEX equipment against all five external hazards. This location is referred to in this document as the FLEX equipment storage building (FESB). If equipment will be stored in another location for a particular function, it is noted in the section for that function.

A7. Considerations for exceptions to the site security plan or other license/site specific requirements will be included in the FLEX support guidelines.

A8. Instrumentation on FLEX equipment will be used to confirm continual performance.

A9. This plan defines strategies capable of mitigating a simultaneous loss of all alternating current (ac) power and loss of normal access to the ultimate heat sink resulting from a beyond-design-basis event by providing adequate capability to maintain or restore core cooling, containment, and SFP cooling capabilities at all units on a site. Though specific strategies are being developed, due to the inability to anticipate all possible scenarios, the strategies are also diverse and flexible to encompass a wide range of possible conditions. These pre-planned strategies developed to protect the public health and safety will be incorporated into the site emergency operating procedures in accordance with established EOP change processes, and their impact to the design basis capabilities of the unit evaluated under 10 CFR 50.59. The plant Technical Specifications contain the limiting conditions for normal unit operations to ensure that design safety features are available to respond to a design basis accident and direct the required actions to be taken when the limiting conditions are not met. The result of the beyond-design-basis event may place the plant in a condition where it cannot comply with certain Technical Specifications and/or with its Security Plan, and as such, may warrant invocation of 10 CFR 50.54(x) and/or 10 CFR 73.55(p) (Reference 12).

Extent to which the guidance, Include a description of any alternatives to the guidance, and JLD-ISG-2012-01 and NEI 12- provide a milestone schedule of planned action.

06, are being followed.

Identify any deviations to JLD-ISG-2012-01 and NEI 12-06.

Ref: JLD-ISG-2012-01 Ref: NEI 12-06 Section 13.1 Sequoyah Nuclear plans to fully comply with the guidance in JLD-ISG-2012-01 (Reference 3) and NEI 12-06 (Reference 2) in implementing FLEX strategies for the Sequoyah site.

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Provide a sequence of events Strategies that have a time constraint to be successful should be and identify any time identified with a technical basis and a justification provided that constraint required for the time can reasonably be met (for example, a walkthrough of success including the technical deployment).

basis for the time constraint.

Describe in detail in this section the technical basis for the time Ref: NEI 12-06 Section 3.2.1.7 constraint identified on the sequence of events timeline Attachment JLD-ISG-2012-01 Section 2.1 1A See attached sequence of events timeline (Attachment 1A).

Technical Basis Support information, see attached NSSS Significant Reference Analysis Reconciliation Table (Attachment 1B)

The sequence of events and any associated times constraints are identified below for Sequoyah Reactor Core Cooling and Heat Removal (steam generators available) strategies for FLEX Phases 1 through Phase 3. See attached sequence of events timeline (Attachment 1A) and the technical basis support information in Attachment 1B for a summary of this information.

Discussion of action items identified in Attachment 1A table: (Non-Flood Event)

1. Declare ELAP - ELAP entry conditions can be verified by control room staff and it is validated that emergency diesel generators are not available. This step is time sensitive and needs to occur within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> following the start of the event to provide operators with guidance to perform ELAP actions.

2. Complete Extended Load Shed for any Vital Battery within 90 minutes (1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) following the start of the event.

3. Align and place in service the 225 kva 480vAC Diesel Generators (480v FLEX Generators). This provides charging current to the 125v DC Vital Batteries and ensures 125v DC Vital Battery power (control) and through the Vital Inverters 120v AC Vital Instrument Power (instrument indication).

4. Debris Removal (Access) - The earliest need for debris removal access paths is to support alignment of the Low Pressure FLEX Pumps to the essential raw cooling water (ERCW) headers at the Intake Pumping Station (IPS). This process will be initiated in order to support FLEX equipment deployment depending on the resources available.

5. Initiate Damage Assessment - Sequoyah will develop a post event damage assessment procedure.

The damage assessment will evaluate and document the condition of plant systems, structures and components (SSCs) after an ELAP event. The assessment will be consistent with the guidelines contained in supplement 5 of Reference 16.

6. Stage and align the Low Pressure (LP) FLEX pumps (Dominator and Triton) - staged and aligned to take suction from the intake channel with discharge routed to the Essential Raw Cooling Water (ERCW) FLEX connections inside the Intake Pumping Station (IPS).

7. Initiate RCS depressurization and cooldown to commence as soon as possible due to RCP seal failure probability. At rated pressure a potential leakage rate of 21 gpm per RCP following the event is possible. An RCS cooldown rate of 75-100 °F per hour should be sustained until stabilized at ~ 300 PSIA Steam Generator (SG) Pressure. Maintain RCS pressure greater than 250 psig to avoid Cold Leg Accumulator (CLA) nitrogen injection into the RCS. The CLAs are maintained at a boron concentration of 2500 - 2700 ppm. Cooldown and depressurization should be stabilized within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

8. Complete 3 MWe FLEX Diesel Generators (6.9KV FLEX Generators), 6.9KV Shutdown Boards and emergency feeder breakers and 480v Shutdown Board alignment. This is to ensure switching at the EDG building and shutdown board rooms are complete, potential board loading is reduced E-8

and interlocks are cleared to allow the emergency feeder breaker to be used to safely power the 6.9KV Shutdown Boards from the 6.9KV FLEX DG.

9. Energize the 6.9KV Shutdown Boards with the 6.9KV FLEX DGs. Place the following components in service and restore pressurizer level: Component Cooling Water Pumps and Safety Injection Pumps (SIPs), as required to recover and maintain RCS Pressurizer level. The SIPs take suction for the RWST which maintains a boron concentration of between 2500 and 2700 ppm.

10. Place the following equipment in service, if required: Verify 6.9KV FLEX DG loading between starts. Auxiliary Air Compressors, Motor Driven Auxiliary Feedwater Pumps and/or Spent Fuel Pool (SFP) Cooling Pump.

11. Stage and align the High Pressure (HP) FLEX pumps (AB el. 669). The primary suction alignment is from the Refueling Water Storage Tanks RWST) which maintains a boron concentration of 2500-2700 ppm). The secondary suction alignment is from the Boric Acid Tank (BAT) which maintains a boron concentration of ~ 6900 ppm. Complete 480v AC power connections for these pumps.

Note: While the TDAFWP is not anticipated to fail, steam generator makeup can be provided by the MDAFWPs, if required, as soon as the 6.9KV FLEX DGs are in service. The IP FLEX pumps will be staged and aligned as soon as feasible (within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />).

12. Stage and align the Intermediate Pressure (IP) FLEX Pumps at the AFWST as backup for SG makeup (backup to the TDAFWPs and MDAFWPs). Suction is aligned from the AFWST and discharge can be routed to FLEX connections upstream of the TDAFWP Level Control Valves (LCVs) (primary) or MDAFWP LCVs (alternate). These are diesel driven pumps.

13. Deploy hoses and spray nozzles to the SFP area as a contingency within 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />. Hoses can be routed to supply makeup from FLEX connections on the refuel floor or from the elevation below the refuel floor. This is the need time based on the most limiting SFP time when boil off occurs (Reference 23).

14. Alternate fuel supply will need to be established within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. This accounts for the 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in which the FLEX equipment fuel supply depletes and the deployment time.

Note: If the Condensate Storage Tanks (CSTs) survive the event they will supply additional water reserve per unit to the Auxiliary Feedwater Pumps.

15. The AFWST will be depleted in 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, makeup options will need to be evaluated and directed.

Potential sources of clean water makeup are the Demineralized Water Storage Tank (DWST), U1 and U2 Primary Water Storage Tanks (PWST). If the AFWST is depleted the operating auxiliary feedwater pumps suction will be realigned to the ERCW headers to extend core cooling. The low pressure FLEX pumps have been aligned to the ERCW headers to provide a raw water input prior to the AFWST depleting. Available raw water in the ERCW headers (without LP FLEX pumps supply) will deplete in 18.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. (Reference 24).

16. Acceptable control room lighting will be available for long term support. This is not a time constraint as control room lighting is available via batteries, and portable lighting will be available if required.

17. The Vital Battery Room and Shutdown Board Room heating, ventilation, and air conditioning (HVAC) study determined that ventilation is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the ELAP event; at which point it can be monitored periodically, if needed (Reference 14).

18. The Main Control Room HVAC study determined that ventilation is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into ELAP event; at which point it can be monitored periodically if needed (Reference 14).

19. The TDAFWP room HVAC study determined that ventilation is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into E-9

ELAP event; at which point it can be monitored periodically if needed (Reference 14).

20. Venting of the SFP area will need to be evaluated within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> based on the SFP time when boil off occurs (Reference 23).

21. A time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is assumed for alignment of a mobile water purification system to provide clean water to refill the AFWST. However, cooling water via the ERCW headers is available to be provided indefinitely.

22. Large fuel truck service will need to be established within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This is based on the depletion of on-site supplies and supplying larger equipment.

Discussion of action items identified in Attachment 1A table: (Flood Event)

Note: An ELAP could occur at anytime during flood preparation or a flood event therefore FLEX equipment and strategies must be staged and ready for implementation if required.

Note: The scenario described below assumes an ELAP event occurs post initial flood warning received from TVAs River System Operations and prior to a Stage 1 warning notification.

This provides a 27 hour3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> period before flood waters reach grade elevation. This flood preparation time period allows for initial use of the same strategy as a non-flood event for Steps 1-9 for stabilizing the plant and staging FLEX equipment for flood mitigation strategy.

1. Declare ELAP - ELAP entry conditions can be verified by control room staff and it is validated that emergency diesel generators are not available. This step is time sensitive and needs to occur within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> following the start of the event to provide operators with guidance to perform ELAP actions.

2. Perform Extended Load Shed for any Vital Battery within 90 minutes (1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) following the start of the event. This ensures 8-hour coping time for the 125v DC Vital Batteries.

3. Align and place in service the 225 kva 480vAC Diesel Generators (480v FLEX Generators). This provides charging current to the 125v DC Vital Batteries and ensures 125v DC Vital Battery power (control) and through the Vital Inverters 120v AC Vital Instrument Power (instrument indication).

4. Verify 125v DC Vital Chargers energized and supplying required load to the 125v DC Vital Batteries.

5. Debris Removal (Access) - The earliest need for debris removal access paths is to support alignment of the Low Pressure FLEX Pumps to the essential raw cooling water (ERCW) headers at the Intake Pumping Station (IPS). This process will be initiated in order to support FLEX equipment deployment depending on the resources available.

6. Damage Assessment - Sequoyah will develop a post event damage assessment procedure. The damage assessment will evaluate and document the condition of plant systems, structures and components (SSCs) after an ELAP event. The assessment will be consistent with the guidelines contained in supplement 5 of Reference 16.

7. Stage and align the Low Pressure (LP) FLEX pumps (Dominator and Triton) - staged and aligned to take suction from the intake channel with discharge routed to the Essential Raw Cooling Water (ERCW) FLEX connections inside the Intake Pumping Station (IPS).

8. Initiate RCS depressurization and cooldown to commence as soon as possible due to RCP seal failure probability. At rated pressure a potential leakage rate of 21 gpm per RCP following the event is possible. An RCS cooldown rate of 75-100 °F per hour should be sustained until stabilized at ~ 300 PSIA Steam Generator (SG) Pressure. Maintain RCS pressure greater than 250 psig to avoid Cold Leg Accumulator (CLA) nitrogen injection into the RCS. The CLAs are maintained at a boron concentration of 2500 - 2700 ppm. Cooldown and depressurization should be stabilized within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

E-10

9. Align the 3MWe FLEX Diesel Generators (6.9KV FLEX Generators), 6.9KV Shutdown Boards and 480v Shutdown Boards for FLEX DG operation. This is to ensure switching at the EDG building and shutdown board rooms are complete, potential board loading is reduced and interlocks are cleared to allow the emergency feeder breaker to be used to safely power the 6.9KV Shutdown Boards from the 6.9KV FLEX DG.

10. Energize the 6.9KV Shutdown Boards with the 6.9KV FLEX DGs. Place the following components in service and restore pressurizer level: Component Cooling Water Pumps and Safety Injection Pumps (SIPs), as required to recover and maintain RCS Pressurizer level. The SIPs take suction for the RWST which maintains a boron concentration of between 2500 and 2700 ppm.

Note: While the TDAFWP is not anticipated to fail, a secondary source of steam generator makeup can be provided by the MDAFWPs, if required, as soon as the 6.9KV FLEX DGs are in service. The IP FLEX pumps will be staged and aligned as soon as feasible (within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />).

11. Place the following equipment in service, if required: Verify 6.9KV FLEX DG loading between starts. Auxiliary Air Compressors, Motor Driven Auxiliary Feedwater Pumps and/or Spent Fuel Pool (SFP) Cooling Pump.

Note: The above design Basis components will be removed from service and protection transitioned to the FLEX strategies prior to flood waters reaching plant grade.

Note: The Auxiliary Feedwater Supply Tank (AFWST) will not be available as a water source once flood water reaches plant grade.

12. Stage and align the second set of Low Pressure (LP) FLEX pumps to take suction from CCW cold water return channel with discharge routed to the ERCW FLEX connections at the old AERCW pumping station. Hoses will remain isolated and pumps out of service until required.

13. Deploy hoses and spray nozzles as a contingency for SFP makeup within 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />. Hoses can be routed to supply makeup from an AB el. 734 ERCW - CCS Spool Piece FLEX connection (next to the CCS Surge Tanks) to the SFP area or from an AB el. 714 FLEX connection to the demineralized water makeup header FLEX connection on AB el. 714. This is based on the time when boil off decreases the water level to 10 feet above the SFP racks, determined in analyses contained in Reference 23.

14. Stage and align the High Pressure (HP) FLEX Pumps (AB el. 669) with suction hoses routed from the RWST FLEX connections on AB el. 669 and discharge hoses routed to the Safety Injection Pump Discharge Header FLEX connection (B Train (primary) or A Train (secondary))

(AB el. 669). Complete 480v power supply connections for these pumps.

15. Stage and align the Intermediate Pressure (IP) FLEX Pumps (AB el. 714) with suction hoses routed from the AB el. 714 ERCW FLEX connections and discharge hoses routed to FLEX connections upstream of the TDAFWP Level Control Valves (LCVs) (primary) (EMSVV el. 706) or MDAFWP LCVs (alternate) (AB el. 714). Complete 480v power supply connections for these pumps.

16. Alternate fuel supply will need to be established within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. This accounts for the 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in which the FLEX equipment fuel supply depletes and the deployment time.

Note: If the Condensate Storage Tanks (CSTs) survive the event they will supply an additional reserve of water per unit to the Auxiliary Feedwater Pumps.

17. The AFWST will be depleted in 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, makeup options will need to be evaluated and directed.

Potential sources of clean water makeup are the Demineralized Water Storage Tank (DWST), U1 and U2 Primary Water Storage Tanks (PWST). If the AFWST is depleted the operating Auxiliary Feedwater System pumps suction will be realigned to the ERCW headers to extend core cooling.

Low Pressure FLEX pumps will be aligned to the ERCW headers to provide a raw water input E-11

prior to the AFWST depleting. Available raw water in the ERCW headers (without LP FLEX pumps supply) would deplete in 18.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. (Reference 24).

18. Acceptable control room lighting will be available for long term support. This is not a time constraint as control room lighting is available via batteries, and portable lighting will be available, if required.

19. The Vital Battery Room and Shutdown Board Room heating, ventilation, and air conditioning (HVAC) study determined that ventilation is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the ELAP event; at which point it can be monitored periodically, if needed (Reference 14).

20. The Main Control Room HVAC study determined that ventilation is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into ELAP event; at which point it can be monitored periodically if needed (Reference 14).

21. The TDAFWP room HVAC study determined that ventilation is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into ELAP event; at which point it can be monitored periodically if needed (Reference 14).

22. Venting of the SFP area will need to be evaluated within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> based on the SFP time when boil off occurs (Reference 23).

23. A time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is assumed for alignment of a mobile water purification system to provide clean water to refill the AFWST. However, cooling water via the ERCW headers is available to be provided indefinitely.

24. A time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is assumed for alignment of mobile boration unit(s) from the Regional Response Center (RRC). This is based on analysis timeline values.

25. Large fuel truck service will need to be established within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This is based on the depletion of on-site supplies and supplying larger equipment.

To confirm the times given above, Sequoyah will prepare procedures for each task, perform time study walkthroughs for each of the tasks under simulated ELAP conditions and account for administrative procedures that may be required to perform the task. In addition, an evaluation on the impact of FLEX response actions on design basis flood mode preparations will be performed. This evaluation will include the potential for extended preparation time for FLEX. (Open Item OI 13)

E-12

Identify how strategies will be Describe how the strategies will be deployed in all modes.

deployed in all modes Ref: NEI 12-06 section 13.1.6 Deployment of FLEX equipment is described for each FLEX function in the subsequent sections below and covers all operating modes. The broad-spectrum deployment strategies do not change for the different operating modes. The deployment strategies from the storage areas to the staging areas are identical and include debris removal, equipment transport, fuel transport, and power sources and requirements. RCS makeup connections are provided for the higher flow rates required during core cooling with SGs unavailable. Each of these strategies and the associated connection points are described in detail in the subsequent sections. The electrical coping strategies are the same for all modes. Figure A3-21 shows a visual representation of the deployment strategy.

Provide a milestone schedule.

This schedule should include:

• Modifications timeline o Phase 1 Modifications o Phase 2 Modifications o Phase 3 Modifications

• Procedure guidance development complete o Strategies o Maintenance

• Storage plan (reasonable protection)

• Staffing analysis completion

• FLEX equipment acquisition timeline

• Training completion for the strategies

• Regional Response Centers operational Ref: NEI 12-06 Section 13.1 The dates specifically required by the order are obligated or committed dates. Other dates are planned dates subject to change. Updates will be provided in the periodic (six month) status reports.

See attached milestone schedule Attachment 2.

E-13

Identify how the programmatic controls will be met.

Ref: NEI 12-06 Section 11 JLD-ISG-2012-01 Section 6.0 Equipment associated with these strategies will be procured as commercial equipment with design, storage, maintenance, testing, and configuration control in accordance with NEI 12-06 Rev. 0 Section 11.

The unavailability of equipment and applicable connections that directly performs a FLEX mitigation strategy will be managed using plant equipment control guidelines developed in accordance with NEI 12-06 Rev. 0 Section 11.5.

Programs and controls will be established to assure personnel proficiency in the mitigation of beyond-design-basis events is developed and maintained in accordance with NEI 12-06 Rev. 0 Section 11.6.

The FLEX strategies and basis will be maintained in an overall program document. Existing plant configuration control procedures will be modified to ensure that changes to the plant design, physical plant layout, roads, buildings, and miscellaneous structures will not adversely impact the approved FLEX strategies in accordance with NEI 12-06 Rev. 0 Section 11.8.

Procedure Guidance Sequoyah is a participant in the PWROG project PA-PSC-0965 and will implement the FLEX Support Guidelines (FSGs) in a timeline to support the implementation of FLEX by December 2015.

The PWROG has generated these guidelines to assist utilities with the development of site-specific procedures to cope with an ELAP in a manner compliant with the requirements of Reference NEI 12-06.

The proposed implementation strategy aligns with the procedure hierarchy described in NEI 12-06 in that actions that maneuver the plant are contained within the typical controlling procedure, and the Flex Support Instructions (FSIs) are implemented as necessary to maintain the key safety functions of Core Cooling, Spent Fuel Cooling, and Containment in parallel with the controlling procedure actions. The overall approach is symptom-based, meaning that the controlling procedure actions and FSIs are implemented based upon actual plant conditions.

Sequoyah will continue participation in PA-PSC-0965 and will update plant procedures upon the completion of the PWROG program. It is anticipated that the following FSGs will be incorporated into existing plant procedures in order to develop the FSG interface:

• Alternate Auxiliary Feedwater (AFW) Suction Source

• Alternate Low Pressure Feedwater

• ELAP Direct Current (DC) Load Shed/Management

• Initial Assessment and FLEX Equipment Staging

• Alternate CST Makeup

• Loss of DC Power

• Alternate RCS Boration

• Long Term RCS Inventory and Temperature Control

• Passive RCS Injection Isolation

• Alternate SFP Makeup and Cooling

• Alternate Containment Cooling

• Transition from FLEX Equipment Maintenance and Testing The FLEX mitigation equipment will be initially tested (or other reasonable means used) to verify E-14

performance conforms to the limiting FLEX requirements. It is expected the testing will include the equipment and the assembled sub-systems to meet the planned FLEX performance. Additionally, Sequoyah will implement the maintenance and testing template upon issuance by the Electric Power Research Institute (EPRI). The template will be developed to meet the FLEX guidelines established in Section 11.5 of Reference 2.

Staffing The FLEX strategies documented in the event sequence analysis assume:

• On-site staff are at administrative minimum shift staffing levels,

• No independent, concurrent events, and

• All personnel on-site are available to support site response Sequoyah will have to address staffing considerations in accordance with Reference 2 to fully implement FLEX at the site.

Configuration Control Per NEI 12-06 and the Interim Staff Guidance (ISG), the FLEX strategies must be maintained to ensure future plant changes do not adversely impact the FLEX strategies.

Therefore, Sequoyah will maintain the FLEX strategies and basis in an overall program document and will modify existing plant configuration control procedures to ensure changes to the plant design, physical plant layout, roads, buildings, and miscellaneous structures will not adversely impact the approved FLEX strategies.

Describe training plan Training plans will be developed for plant groups such as the emergency response organization (ERO), Fire, Security, Emergency Preparedness (EP), Operations, Engineering, and Maintenance. The training plan development will be done in accordance with Sequoyah procedures using the Systematic Approach to Training, and will be implemented to ensure that the required Sequoyah staff is trained prior to implementation of FLEX.

Describe Regional The nuclear industry will establish two RRCs to support utilities during Response Center plan beyond design basis events. Each RRC will hold five sets of equipment, four sets of which will be able to be fully deployed when requested, the fifth set will have equipment in a maintenance cycle. Equipment will be moved from an RRC to a local Assemble Area, established by the Strategic Alliance for FLEX Emergency Response (SAFER) team and TVA. Communications will be established between Sequoyah and the SAFER team and required equipment moved to the site as needed. First arriving equipment, as established during development of Sequoyahs playbook, will be delivered to the site within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from the initial request.

TVA has established an agreement with the SAFER team in accordance with the requirements of Section 12 of Reference 2.

Sequoyah has determined Phase 3 equipment staging locations.

Notes:

1. Maintenance and testing, configuration control, training, and regional response center plans are currently being developed.

E-15

Maintain Core Cooling & Heat Removal Determine Baseline coping capability with installed coping 1 modifications not including FLEX modifications, utilizing methods described in Table 3-2 of NEI 12-06:

• AFW/EFW

• Depressurize SG for Makeup with Portable Injection Source

• Sustained Source of Water Reference 3: JLD-ISG-2012-01 Sections 2 and 3 PWR Installed Equipment Phase 1 Core Cooling with SGs Available The coping strategy is to remove heat from the RCS by providing cooling water to the four SGs. The plant is assumed to be operating at full power at the start of the event. An SBO occurs to start the scenario and all ac power is assumed to be lost. The TDAFWP will start as designed and provide cooling through the SGs. Initial alignment of the TDAFWP suction is to the AFWST. The AFWST will provide approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> of inventory to the suction of the TDAFWPs for each unit before the AFWST is depleted. If the CSTs survive the event an additional 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> per unit of cooling water would be available.

When the AFWST is depleted, suction flow to the TDAFWP can be provided by standing water in the ERCW headers for an additional 18.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> as summarized in Reference 24.

Core Cooling with SGs Not Available Reactor core cooling and heat removal with SGs not available is provided during Phase 1 by heating up and boiling of the RCS coolant inventory. The lowest allowed level in the RCS, when SGs are not available to provide core cooling, is not more than one foot below the vessel flange during the removal of the reactor vessel head.

RCS inventory during Phase 1 may be maintained by gravity feed from the RWST at each unit. The ability of the RWST at each unit to provide a gravity feed to the RCS is limited by the RWST fluid height, line losses through the gravity feed path, and pressure within the RCS.

If it is determined that gravity feed is not effective to cool the RCS and prevent fuel damage, Sequoyah will take actions to proceduralize administrative controls to pre-stage FLEX equipment prior to entering a condition where the SGs cannot provide adequate core cooling. (Open Item OI-12)

Details:

Provide a brief description Confirm that procedure/guidance exists or will be developed to support of Procedures / Strategies / implementation.

Guidelines SBO Emergency Procedure ECA-0.0 (Reference 17) currently addresses implementation of this strategy. The strategies in ECA-0.0 will be supported by the appropriate FSI for this strategy.

Identify Modifications List modifications and describe how they support coping time.

1. AFWST and connections to Unit 1 and Unit 2 Auxiliary Feedwater System. (DCN Future) - Provides 500,000 gallons of demineralized water from a seismically qualified source.

2. 8 Hour Battery Coping. (DCN Future) - Increases battery coping capability.

1 Coping modifications consist of modifications installed to increase initial coping time, i.e., generators to preserve vital instruments or increase operating time on battery powered equipment.

E-16

3. The backup instrument air/nitrogen supply to the SG Atmospheric Relief Valves (ARVs) and Auxiliary Feedwater (AFW) Level Control Valves (LCVs) will be moved to above the probable maximum flood (PMF) elevation for flood mode response. (DCN 23192)

Key Reactor Parameters 1. SG Wide Range Level or Narrow Range Level with AFW Flow indication

2. SG Pressure

3. AFWST Level RCS instrumentation that is assumed to also be available for this function:

1. Core Exit Thermocouple (CET) Temperature**

2. RCS Hot Leg (HL) Temperature (Thot) if CETs not available

3. RCS Cold Leg (CL) Temperature (Tcold)*

4. RCS Wide Range Pressure

5. Pressurizer Level

6. Reactor Vessel Level Indicating System (RVLIS) (backup to Pressurizer level) - available for up to 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> for limiting flood scenario, at which point pressurizer level is available again.

7. Neutron Flux For all instruments listed above the normal power source and the long-term power source is the 125v DC Vital Battery.

• This instrumentation is only available until flood water enters the auxiliary instrument room. The potential validating indicator for Tcold is SG pressure when natural circulation is occurring. This substitution is allowed by guidance provided in Reference 16.

• • This instrumentation is only available until flood water enters the auxiliary instrument room (Open Item OI 26 closed). The potential validating indicator for CETs is RCS HL. This substitution is allowed by guidance provided in Reference 16.

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Notes:

1. Core cooling strategies are provided for conditions where SGs are available or where SGs are not available but a sufficient RCS vent has been established to support core cooling. This assumption is per the guidance of NEI 12-06 FAQ 2012-19. Other configurations are not considered as these occur at short durations that are exempted per NEI-12-06 Table D.

E-17

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 2 Provide a general description of the coping strategies using on-site portable equipment including station modifications that are proposed to maintain core cooling. Identify methods and strategy(ies) utilized to achieve this coping time.

Core Cooling with SGs Available Transition to Phase 2 is required before the AFWST inventory and standing water in the ERCW headers is depleted at 18.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> as summarized in Reference 24.

To provide an unlimited supply of water for core cooling during Phase 2, Low Pressure (LP) FLEX Pumps will be staged at the IPS and take suction from the intake channel and discharge to 4 ERCW FLEX connections inside the IPS. They will be used to pressurize the ERCW headers which can then be used for direct supply to the TDAFWP suction, if required. Surviving, non-seismic, clean water tanks can also be used to refill the AFWST using transfer pumps.

An Intermediate Pressure (IP) FLEX pump will be provided for supplying water to the SGs for core cooling after operating conditions of the TDAFWP cannot be maintained. The IP FLEX pumps will supply water to FLEX connections upstream of the TDAFWPs or the Motor Driven Auxiliary Feedwater Pumps (MDAFWP)

Level Control valves (LCVs). The IP FLEX pumps staging location for a non-flood condition is near the AFWST which is the suction source for this condition. The IP FLEX pump staging location for a flood condition would be on AB el. 669 with suction supplied from the ERCW FLEX Connections supplied with raw water from the LP FLEX Pumps. Discharge hose routing would be the same as for a non-flood event.

The storage locations, deployment paths and staging locations for the FLEX equipment are provided in .

For non-flood conditions, Sequoyah will gradually transition to a long term core cooling strategy. This will include the use of the LP FLEX pumps on-site to provide a source of cooling water flow to the component cooling system (CCS) heat exchangers. The 6.9 KV FLEX DGs could be used to repower components such as the Auxiliary Air Compressors, MDAFWPs, CCSPs, select ventilation equipment and other components as need and load capability allows.

For the flood conditions the plant would supply water to the SGs using the IP FLEX pumps supplied from the ERCW headers.

Core Cooling with SGs Not Available For an event that occurs with a unit in core cooling with SGs not available, the transition to Phase 2 strategies will be required as inventory is lost from the RCS. Reactor core cooling and heat removal will be provided by using the IP FLEX pump to inject water into the RCS via the Safety Injection System FLEX connections.

Core cooling is maintained through heat removal from the RCS via coolant boil off. Prior to loss of gravity feed from the RWST, the intermediate pressure FLEX pump must be aligned to take suction from the RWST or another acceptable alternate coolant source and deliver the coolant to the RCS.

The connections utilized for RCS Inventory Control/Long-Term Subcriticality will also be utilized for reactor core cooling and heat removal with SGs not available (Modes 5 and 6). These connections are described in the RCS inventory control section. In addition, a flushing flow of 123 gpm at atmospheric conditions is required at 70 hours8.101852e-4 days <br />0.0194 hours <br />1.157407e-4 weeks <br />2.6635e-5 months <br /> in order to preclude the RCS fluid from the incipient boric acid precipitation point.

Details:

Provide a brief description Confirm that procedure/guidance exists or will be developed to support of Procedures / Strategies / implementation with a description of the procedure / strategy / guideline.

Guidelines Procedures and guidance to support deployment and implementation, including interfaces to EOPs, special event procedures, abnormal event E-18

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 2 procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance and Sequoyahs strategy aligns with the generic guidance and will consider the nuclear steam supply system (NSSS) specific guidance once available.

Identify modifications List modifications necessary for Phase 2

1. The backup instrument air supply lines to the SG Atmospheric Relief Valves (ARVs) and Auxiliary Feedwater (AFW) Level Control Valves (LCVs) will be moved to above the probable maximum flood (PMF) elevation for flood condition response. (DCN23192)

2. Connections will be made on the ERCW headers in the Auxiliary Building for supplying water to the CST or the intermediate pressure FLEX pump. (DCNFuture)

3. The primary connection point for SG cooling will be upstream of the SG LCVs on the TDAFWP discharge line. (DCNFuture)

4. The secondary connection point for SG cooling will be upstream of the SG LCVs in both the train A and train B MDAFWP discharge piping. A connection to both trains is needed for the secondary connection to ensure feed to all four SGs. (DCNFuture)

5. Auxiliary Feedwater Supply Tank (AFWST). (DCNFuture)

6. New connections to take suction from the AFWST are required.

(DCNFuture)

7. New connections will be made at the ERCW headers in the CCW Building for the low pressure FLEX Pumps to pressurize the ERCW headers during non-flood and flood conditions. (DCNFuture)

8. New connections will be made at the ERCW headers at the old AERCW pumping station to allow the low pressure FLEX Pumps to pressurize the ERCW headers during flood conditions. (DCNFuture)

9. New connections will be made to the Primary Water Storage Tank (PWST) and Demineralized Water Storage Tank (DWST) for transferring water to refill the AFWST. (DCNFuture)

10. FLEX connections at the Safety Injection Pumps for HP FLEX Pumps RCS makeup. (DCNFuture)

11. RWST FLEX connections for HP FLEX pump or IP FLEX Pump (mode 5 &6) suction source. (DCNFuture)

12. BAT FLEX connection for HP FLEX Pump suction supply.

(DCNFuture)

13. FLEX Equipment Storage Building (FESB). (DCNFuture)

14. 225kva DGs (480v FLEX DGS). DCNFuture

15. 3 MWe DGs (6.9KV FLEX DGs) (DCN 23197)

16. 8 Hour Battery Coping. (DCNFuture)

E-19

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 2 Key Reactor Parameters List instrumentation credited or recovered for this coping evaluation.

1. SG Wide Range Level or Narrow Range Level with AFW Flow indication

2. SG Pressure

3. AFWST Level RCS instrumentation that is assumed to also be available for this function:

1. CET Temperature**

2. RCS HL Temperature (Thot) if CETs not available

3. RCS CL Temperature (Tcold)*

4. RCS Wide Range Pressure

5. Pressurizer Level

6. RVLIS (backup to Pressurizer level) - available for up to 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> for limiting flood scenario, at which point pressurizer level is available again.

7. Neutron Flux For all instrumentation listed above the normal power source and the long-term power source is the 125v DC Vital Battery.

• This instrumentation is only available until flood water enters the auxiliary instrument room. The potential validating indicator for Tcold is SG pressure when natural circulation is occurring. This substitution is allowed by guidance provided in Reference 16.

• • This instrumentation is only available until flood water enters the auxiliary instrument room (Open item OI 26 closed). The potential validating indicator for CETs is RCS HL. This substitution is allowed by guidance provided in Reference 16.

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Storage / Protection of Equipment Describe storage / protection plan or schedule to determine storage requirements Seismic Portable equipment required to implement this FLEX strategy will be maintained in the FESB, the Auxiliary Building and Intake Pumping Station, which are designed for seismic loading in excess of the minimum requirements of American Society of Civil Engineers (ASCE) 7-10. The design of the FESB provides a minimum High Confidence of Low Probability Failure (HCLPF) of 2x SSE. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Flooding Portable equipment required to implement this FLEX strategy will be Note: if stored below current flood level, maintained in the FESB which is sited in a suitable location that is above then ensure procedures exist to move the PMF level and as such is not susceptible to flooding from any source.

equipment prior to exceeding flood level. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Severe Storms with High Portable equipment required to implement this FLEX strategy will be Winds maintained in the FESB, which is designed to meet or exceed the licensing basis high wind hazard for Sequoyah. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

E-20

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 2 Snow, Ice, and Extreme Cold The FESB will be evaluated for snow, ice and extreme cold temperature effects and heating will be provided as required to assure no adverse effects on the FLEX equipment. The FESB will have a standalone HVAC system.

The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

High Temperatures The FESB will be evaluated for high temperature effects and ventilation will be provided as required to assure no adverse effects on the FLEX equipment. The FESB will have a standalone HVAC system. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Deployment Conceptual Design The figures provided in Attachment 3 show the deployment paths from each of the storage locations to the staging locations.

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

SGs Available Primary connection modifications: All FLEX equipment connection

• A tee will be added to the points will be designed to meet or The primary connection for the TDAFWP discharge line. exceed Sequoyah design basis Intermediate Pressure (IP) FLEX

• An isolation valve will be SSE protection requirements.

pumps will be located in the steam valve room upstream of the LCVs added to the main line The primary connection is located on the TDAFWP discharge piping. upstream of connection. inside the West Valve Vaults. The

• An isolation valve will be West Valve Vault is a safety For this alignment during non- added to the new branch. related structure and is protected flood conditions, suction to the IP

• Storz cap/adapter will be from all external hazards except FLEX pump will be taken from added to new branch. flooding. For flood conditions, the AFWST or ERCW headers.

AFWST modifications: procedures will ensure that hoses During flood conditions suction are connected before flood levels will be taken from the ERCW Storz hose connections will be reach the connection.

headers. Discharge of the IP provided with the new AWST.

FLEX pump will be to the The connections to the AFWST connection points shown in ERCW modifications: and ERCW will be seismically , Figure A3-1. The For non-flood conditions, one set qualified and missile protected.

proposed hose routing for the of Low Pressure (LP) FLEX For connections required during primary connection and the pumps will be staged near the flood conditions, procedures will associated equipment staging area CCW intake pumping station. The ensure that hoses are connected can be found in Attachment 3, existing ERCW piping in the before flood levels reach the Figures A3-3 through A3-5. CCW building will be modified to connection.

ERCW connections can be found add isolation valves with hose Connections to other tanks are not in Attachment 3, Figure A3-13. connections to allow the ERCW protected since the connections are headers to be pressurized. to non-protected tanks and would For flood conditions, a second set only be available if the tank of low pressure FLEX pumps will survives the event. These be staged next to old AERCW connections are used to provide pumping station. The existing additional capability above the ERCW piping at the old AERCW minimum FLEX requirements.

pumping station will be modified E-21

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 2 to add isolation valves with hose connections to allow the ERCW headers to be pressurized.

To supply water to the suction of the IP FLEX pumps, existing ERCW headers cleanout ports in the Auxiliary Building el. 714 will be utilized. The cleanout ports will be modified to add a Storz hose connection.

Other tank modifications:

An isolation valve and Storz hose connections will be added to the PWST and DWST for use of water transfer pumps to provide clean water to refill the AWST or direct supply.

SGs Available Secondary connection All FLEX equipment connection modifications: points will be designed to meet or The secondary connection will be exceed Sequoyah design basis located in the Auxiliary Building

• Hard piping will be installed SSE protection requirements.

on el. 714 upstream of the LCVs between the high pressure fire on the MDAFWP discharge protection (HPFP) Train A The secondary connection is piping. and Train B flood conditions located inside the Auxiliary supply piping and the Building. The Auxiliary Building For this alignment, suction will be MDAFWP Train A and Train is a safety related structure and is taken from the AFWST or ERCW B piping which will replace protected from all external hazards and discharged through the IP the existing removable spool except flooding. For flood FLEX Pumps to the connection pieces. conditions, procedures will ensure points shown in Attachment 3,

• A tee will be added to this that hoses are connected before Figure A3-2. The secondary piping flood levels reach the connection.

connection point is for flood conditions. The proposed hose

• Add isolation valve to either The connections to the ERCW will routing for the secondary side of new tee. be seismically qualified and connection and the associated

• Add isolation valve on new missile protected. For connections equipment staging area can be branch. required during flood conditions, found in Attachment 3, Figures

• Storz cap/adapter will be procedures will ensure that hoses A3-3 through A3-5. added to new branch. are connected before flood levels AFWST, ERCW, and other tank reach the connection.

ERCW connections can be found in Attachment 3, Figure A3-13. modifications: Connections to non-seismic tanks Same as primary. are not protected and would only be available if the tank survives the event. These connections are used to provide additional capability above the minimum FLEX requirements.

SGs Not Available Primary Connection Modification All FLEX equipment connection

• Install tee or weldolet, points will be designed to meet or E-22

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 2 When SGs are not available,

• Add two isolation valves exceed Sequoyah design basis suction will be taken from the

• Add a hose adapter SSE protection requirements.

RWST and discharged through the BAT Modification The primary connection at the IP FLEX pumps staged in the

• Install tees on discharge lines Safety Injection Pump (SIP) Train auxiliary building, near the of BAT A. A and BAT connection are located primary connection point.

• Add an isolation valve on the inside the Auxiliary Building. The branch. Auxiliary Building is a safety

• Add a Storz adapter with cap related structure and is protected on branch. from all external hazards except flooding. For flood conditions, RWST modifications: procedures will ensure that hoses

• Install pipe taps on RWST are connected before flood levels supply lines to the Refueling reach the connection.

Water Purification Pumps on AB el. 669. The RWST connection is located inside the AB on el. 669. For

• Add an isolation valves on connections required during flood these connection locations.

conditions, procedures will ensure

• Add a Storz adapter with cap that hoses are connected before on branch.

flood levels reach the connection.

SGs Not Available The secondary connection All FLEX equipment and modification for steam generators connection points will be designed When SGs are not available, not available is identical to the to meet or exceed Sequoyah suction will be taken from the primary, except for on Safety design basis SSE protection RWST and discharged through the Injection Pump (SIP) Train B requirements.

intermediate pressure FLEX discharge.

pumps staged near the RWST The secondary connection and connection to the secondary BAT and RWST Modification BAT connection are located inside connection point. Same as primary. the Auxiliary Building. The Auxiliary Building is a safety related structure and is protected from all external hazards except flooding. For flood conditions, procedures will ensure that hoses are connected before flood levels reach the connection.

The RWST connections are located inside the AB on el. 669.

For connections required during flood conditions, procedures will ensure that hoses are connected before flood levels reach the connection.

Notes:

1. System modifications are described in the Modifications section above and are illustrated in Attachment 3.

2. Figures A3-3 through A3-5 in Attachment 3 provide the deployment routes from the staging locations for each Intermediate Pressure (IP) FLEX pump to the pump suction source and to the primary and secondary connection points on the AFW system.

E-23

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 2

3. Core cooling strategies are provided for conditions where SGs are available or where SGs are not available but a sufficient RCS vent has been established to support core cooling. This assumption is per the guidance of NEI 12-06 FAQ 2012-19. Other configurations are not considered as these occur at short durations that are exempted per NEI-12-06 Table D.

E-24

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 3 Provide a general description of the coping strategies using phase 3 equipment including modifications that are proposed to maintain core cooling. Identify methods and strategy(ies) utilized to achieve this coping time.

Core Cooling with SGs Available For Phase 3, Sequoyah will continue the Phase 2 coping strategies with additional assistance provided from offsite equipment/resources. Backup or alternate Phase 2 FLEX equipment will be provided by the RRC as necessary. Additionally, purification of water at each unit will be supported by a mobile water purification unit from the RRC. This unit will process water from the Tennessee River or other raw water sources to remove particulate and demineralize the water. The purification unit will be self-supported. This water would then be used to refill or makeup to the AFWST.

Core Cooling with SGs Not Available Reactor core cooling with SGs not available is adequately maintained via the Phase 2 strategy; however, borated sources are limited. Phase 3 deployment of a unit capable of generating borated water from the water processed through the purification unit can further extend coping times with respect to RCS inventory management.

Sequoyah will determine where Phase 3 equipment will be staged (Open item OI-5).

Details:

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance and Sequoyah's strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Finally, Sequoyah will include in procedures notification of the RRC to arrange for delivery and deployment of off-site equipment and sufficient supplies of commodities.

Identify modifications Each of the Phase 3 strategies will utilize common connections where required as described for the Phase 2 connections to prevent any compatibility issues with the offsite equipment.

Key Reactor Parameters List instrumentation credited or recovered for this coping evaluation.

1. SG Wide Range Level or Narrow Range Level with AFW Flow indication

2. SG Pressure

3. AFWST Level RCS instrumentation that is assumed to also be available for this function:

1. CET Temperature**

2. RCS HL Temperature (Thot) if CETs not available

3. RCS CL Temperature (Tcold)*

4. RCS Wide Range Pressure

5. Pressurizer Level

6. RVLIS (backup to Pressurizer level) - available for up to 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> for limiting flood scenario, at which point pressurizer level is available again.

7. Neutron Flux E-25

Maintain Core Cooling & Heat Removal PWR Portable Equipment Phase 3 For all instruments listed above the normal power source and the long-term power source is the 125v DC Vital Battery.

• This instrumentation is only available until flood water enters the auxiliary instrument room. The potential validating indicator for Tcold is SG pressure when natural circulation is occurring. This substitution is allowed by guidance provided in Reference 16

• • .This instrumentation is only available until flood water enters the auxiliary instrument room (Open Item OI 26 closed). The potential validating indicator for CETs is RCS HL. This substitution is allowed by guidance provided in Reference 16.

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Deployment Conceptual Design Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

A mobile water purification Each of the Phase 3 strategies will All FLEX equipment and system will be the first priority utilize common connections as connection points will be designed and would enable water from the described for the Phase 2 to meet or exceed Sequoyah Tennessee River or other raw connections to prevent any design basis SSE protection water source to be purified. This compatibility issues with the requirements.

unit would process the water offsite equipment.

The system will take suction source and discharge improved directly from the Tennessee River quality water to the AFWST. This or other raw water source. The unit would be self-supported.

discharge connections will be identical to the ones used for Phase 2. The protection of those connection points is described in the section for Phase 2.

Notes:

1. Core cooling strategies are provided for conditions where Steam Generators are available or where Steam Generators are not available but a sufficient RCS vent has been established to support core cooling. This assumption is per the guidance of NEI 12-06 FAQ 2012-19. Other configurations are not considered as these occur at short durations that are exempted per NEI-12-06 Table D.

E-26

Maintain RCS Inventory Control Determine Baseline coping capability with installed coping 2 modifications not including FLEX modifications, utilizing methods described in Table 3-2 of NEI 12-06:

• RCS makeup required (standard design RCP seals)

• All Plants Provide Means to Provide Borated RCS Makeup PWR Installed Equipment Phase 1:

Provide a general description of the coping strategies using installed equipment including modifications that are proposed to maintain RCS inventory control. Identify methods (Low Leak RCP Seals and/or borated high pressure RCS makeup) and strategy(ies) utilized to achieve this coping time.

This section discusses RCS inventory control and subcriticality issues for conditions where steam generators are available. RCS inventory control and subcriticality issues for conditions where steam generators are not available are addressed in the reactor core cooling and heat removal section of this report.

Following the declaration of an ELAP, a plant cooldown will be initiated at approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of ELAP event. Natural circulation is maintained by ensuring adequate RCS inventory.

Sequoyah Unit 1 and Unit 2 have standard Westinghouse RCP seals and given an ELAP event at rated RCS pressure a potential RCP seal leakage rate of 21 gpm exists.

Utilizing WCAP-17601 methodology (Reference 7), Reference 10 summarizes the limiting plant specific scenarios for RCS inventory control, shutdown margin, and Mode 5/Mode 6 boric acid precipitation control with respect to the guidelines set forth in NEI 12-06 (Reference 2).

RCS inventory is a significant concern for the ELAP scenario due to the RCP seal design. Timely RCS cooldown and depressurization at 75 to 100°F per hour to ~ 300 PSIG SG pressure should result in an RCS pressure of ~325 PSIG and ~ 425°F Tavg. Holding RCS pressure to greater than 250 PSIG ensures no nitrogen injection into the RCS from Cold Leg Accumulators. RCS makeup is required to compensate for the RCP seal leakage and from shrinkage due to cooldown. For Phase 1 RCS makeup is provided from the Safety Injection System Cold Leg Accumulators. RCP seal leakage would be greatly reduced from the reduction in RCS pressure.

Details:

Provide a brief description Confirm that procedure/guidance exists or will be developed to support of Procedures / Strategies / implementation Guidelines Loss of all AC Power ECA-0.0 addresses all procedural guidance required for maintaining RCS inventory during Phase 1. Procedures and guidance to support implementation of a boration strategy, including interfaces to EOPs, special event procedures, abnormal event procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify Modifications List modifications

1. 8 Hour Battery Coping. (DCNFuture)

2. The backup instrument air supply to the SG Atmospheric Relief Valves 2

Coping modifications consist of modifications installed to increase initial coping time, i.e., generators to preserve vital instruments or increase operating time on battery powered equipment.

E-27

Maintain RCS Inventory Control (ARVs) and Auxiliary Feedwater (AFW) Level Control Valves (LCVs) will be moved to above the probable maximum flood (PMF) elevation for flood mode response. (DCN 23192)

3. Auxiliary Feedwater Supply Tank (AFWST). (DCNFuture)

4. New connections to take suction from the AFWST are required.

(DCNFuture)

Key Reactor Parameters List instrumentation credited for this coping evaluation.

1. CET Temperature**

2. RCS HL Temperature (Thot) if CETs not available

3. RCS CL Temperature (Tcold)*

4. RCS Wide Range Pressure

5. RCS Passive Injection Level

6. Pressurizer Level

7. RVLIS (backup to pressurizer level) - available for up to 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> for limiting flood scenario, at which point pressurizer level is available again.

8. Neutron Flux For all instruments listed above the normal power source and the long-term power source is the 125v DC Vital Battery.

• This instrumentation is only available until flood water enters the auxiliary instrument room. The potential validating indicator for Tcold is SG pressure when natural circulation is occurring. This substitution is allowed by guidance provided in Reference 16.

• • This instrumentation is only available until flood water enters the auxiliary instrument room (Open Item OI 26 closed). The potential validating indicator for CETs is RCS HL. This substitution is allowed by guidance provided in Reference 16.

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Notes: None E-28

Maintain RCS Inventory Control PWR Portable Equipment Phase 2:

Provide a general description of the coping strategies using on-site portable equipment including modifications that are proposed to maintain RCS Inventory Control. Identify methods (Low Leak RCP Seals and/or borated high pressure RCS makeup) and strategy(ies) utilized to achieve this coping time.

This section discusses RCS inventory control and subcriticality issues for conditions where SGs are available. RCS inventory control and subcriticality issues for conditions where SGs are not available are addressed in the reactor core cooling and heat removal section of this report.

Following the declaration of an ELAP, a plant cooldown will be initiated at approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of ELAP event. Natural circulation is maintained by ensuring adequate RCS inventory.

Sequoyah Unit 1 and Unit 2 have standard Westinghouse RCP seals and given an ELAP event and at rated RCS pressure a potential RCP seal leakage rate of 21 gpm exists.

Utilizing WCAP-17601 methodology (Reference 7), Reference 11 summarizes the limiting plant specific scenarios for RCS inventory control, shutdown margin, and Mode 5/Mode 6 boric acid precipitation control with respect to the guidelines set forth in NEI 12-06 (Reference 2).

RCS inventory is a significant concern for the ELAP scenario due to the RCP seal design. Timely RCS cooldown and depressurization at 75 to 100°F per hour to ~ 300 PSIG SG pressure should result in an RCS pressure of ~325 PSIG and ~ 425°F Tavg. Holding RCS pressure to greater than 250 PSIG ensures no nitrogen injection into the RCS from Cold Leg Accumulators. RCS makeup is required to compensate for the RCP seal leakage and from shrinkage due to cooldown. 6.9KV switchgear, 6.9KV and 480v Shutdown Boards are aligned and powered by the 6.9KV FLEX DGs within 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of the event. With the 6.9KV Shutdown Boards energized CCS pumps and Safety Injection Pumps are restored taking suction from the RWST (2500-27000 ppm boron) and injecting through all 4 cold legs to recover RCS pressurizer level.

RCP seal leakage would be greatly reduced from the reduction in RCS pressure. The SIP operation would be as needed to maintain pressurizer level until the HP FLEX Pump assumed the task. A HP FLEX Pump would be available at 8.5 to 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> from the event. The HP FLEX pump suction would be routed from the BAT to a Safety Injection Pump discharge header FLEX connection. At depletion of the BAT HP FLEX Pumps suction would be transferred to the RWST FLEX connection.

Sequoyah Nuclear Plant has used plant specific ELAP analyses performed with the NOTRUMP computer code to support the mitigating strategy in its Overall Integrated Plan (OIP). The use of NOTRUMP was limited to the thermal-hydraulic conditions before reflux condensation initiates. The initiation of reflux condensation cooling is defined 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.

The analyses and evaluations supporting the OIP demonstrate that the FLEX RCS make-up pump is being implemented prior to the loop flow rate decreasing below the loop flow rate corresponding to the definition of the onset of reflux cooling.

Sequoyah Nuclear Plant will abide by the position expressed by the NRC staff in the letter dated January 8, 2014 regarding the boron mixing issue for PWRs (Adams Accession No. ML13276A183). The NRC letter states that the NRC staff has reviewed the information submitted to date and concluded that use of the industry approach dated August 15, 2013, entitled Westinghouse Response to NRC Generic Request for Additional Information (RAI) on Boron Mixing in Support of the Pressurized Water Reactor Owners Group (PWROG), ML13235A135, is acceptable with clarifications listed in the letter.

FLEX bases and strategies are consistent with NRC Condition 2a: Adequate borated makeup should be provided such that the loop flow rate in two-phase natural circulation does not decrease below the loop flow rate corresponding to single phase natural circulation.

The analyses and evaluations supporting the OIP demonstrate that the FLEX RCS make-up pump is being implemented one hour prior to the loop flow rate decreasing below the loop flow rate corresponding to E-29

Maintain RCS Inventory Control PWR Portable Equipment Phase 2:

single-phase natural circulation for the assumed highest applicable leakage rate of (put plant-specific value here) gpm at normal operating pressure and temperature for the reactor coolant pump seals and unidentified reactor coolant system leakage. Therefore, the boron mixing criteria are met.

Details:

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify modifications List modifications necessary for Phase 2

1. The backup instrument air supply to the SG Atmospheric Relief Valves (ARVs) and Auxiliary Feedwater (AFW) Level Control Valves (LCVs) will be moved to above the probable maximum flood (PMF) elevation for flood mode response. (DCN 23192)

2. FLEX connections will be made on the ERCW headers in the Auxiliary Building el. 714 for supplying water to the Intermediate Pressure FLEX pump. (DCN future)

3. The primary connection point for SG cooling will be upstream of the SG LCVs on the TDAFWP discharge line. (DCN future)

4. The secondary connection point for SG cooling will be upstream of the SG LCVs in both the train A and train B MDAFWP discharge piping.

A connection to both trains is needed for the secondary connection to ensure feed to all four SGs. (DCN future)

5. Auxiliary Feedwater Supply Tank (AFWST). (DCN future)

6. New connections to take suction from the AFWST are required. (DCN future)

7. New connections will be made at the ERCW headers in the Intake Pumping Station (IPS) for the Low Pressure FLEX Pumps to pressurize the ERCW headers during non-flood and flood conditions.

(DCN future)

8. New connections will be made at the ERCW headers at the old AERCW pumping station for the Low Pressure FLEX Pumps to pressurize the ERCW headers during flood conditions. (DCN future)

9. New FLEX connections will be made to the Primary Water Storage Tanks (PWSTs) and Demineralized Water Storage Tank to transfer water to the AFWST. (DCN future)

10. FLEX connections at the Safety Injection Pumps for HP FLEX Pumps RCS makeup. (DCN future)

11. RWST FLEX connections for HP FLEX pump or IP FLEX Pump (mode 5 &6) suction source. (DCN future)

12. BAT FLEX connection for HP FLEX Pump suction supply.(DCN E-30

Maintain RCS Inventory Control PWR Portable Equipment Phase 2:

future)

13. FLEX Equipment Storage Building (FESB). (DCN future)

14. 225kva DGs (480v FLEX DGs). (DCN future)

15. 3 MWe DGs (6.9KV FLEX DGs) (DCN 23197)

16. 8 Hour Battery Coping. (DCN future)

Key Reactor Parameters List instrumentation credited or recovered for this coping evaluation.

1. CET Temperature**

2. RCS HL Temperature (Thot) if CETs not available

3. RCS CL Temperature (Tcold)*

4. RCS wide range pressure

5. Pressurizer Level

6. RVLIS (backup to Pressurizer level) - available for up to 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> for limiting flood scenario, at which point pressurizer level is available again.

7. Neutron Flux For all instruments listed above the normal power source and the long-term power source is the 125v DC Vital Battery.

• This instrumentation is only available until flood water enters the auxiliary instrument room. The potential validating indicator for Tcold is SG pressure when natural circulation is occurring. This substitution is allowed by guidance provided in Reference 16.

• • This instrumentation is only available until flood water enters the auxiliary instrument room (Open Item OI 26 closed). The potential validating indicator for CETs is RCS HL. This substitution is allowed by guidance provided in Reference 16.

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Storage / Protection of Equipment:

Describe storage / protection plan or schedule to determine storage requirements Seismic In addition to equipment being stored in the FESB (as described in the Reactor Core Cooling and Heat Removal section) for this function, equipment will be stored in the Auxiliary Building, which is seismically qualified. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Flooding In addition to equipment being stored in the FESB (as described in the Note: if stored below current flood level, Reactor Core Cooling and Heat Removal section) for this function, then ensure procedures exist to move equipment will be stored in the Auxiliary Building. Equipment required equipment prior to exceeding flood level. for this function will be stored so that it can be deployed prior to any concerns with flooding. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Severe Storms with High In addition to equipment being stored in the FESB (as described in the Winds Reactor Core Cooling and Heat Removal section) for this function, equipment will be stored in the Auxiliary Building, which is protected E-31

Maintain RCS Inventory Control PWR Portable Equipment Phase 2:

from high winds. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Snow, Ice, and Extreme In addition to equipment being stored in the FESB (as described in the Cold Reactor Core Cooling and Heat Removal section) for this function, equipment will be stored in the Auxiliary Building, which is an environmentally controlled building and provides protection from snow, ice, and extreme cold effects. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

High Temperatures In addition to equipment being stored in the FESB (as described in the Reactor Core Cooling and Heat Removal section) for this function, equipment will be stored in the Auxiliary Building, which is an environmentally controlled building and provides protection from high temperature effects. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Deployment Conceptual Modification (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed protected to the point of use.

The primary RCS connection Primary Connection Modification All FLEX equipment and will be on the SIP Train A connection points will be designed

• Install tee or weldolet discharge line, in the SIP room. to meet or exceed Sequoyah This connection is used only

• Add two isolation valves design basis SSE protection during non-flood conditions.

• Add a hose adapter requirements.

For this alignment, suction will BAT Modification The primary connection and BAT be taken from the BATs or

• Install tees on discharge line connection are located inside the RWST and discharged through of BATs. Auxiliary Building. The Auxiliary the high pressure FLEX pumps

• Add an isolation valve on the Building is a safety related to the existing connection points branch. structure and is protected from all shown in Attachment 3, Figure

• Add a Storz adapter with cap external hazards except flooding.

A3-6. The proposed hose on branch. The RWST connection will be routing for the primary RWST modifications: seismically qualified and missile connection and the associated protected. For connections equipment can be found in

• Install pipe taps on RWST required during flood conditions, , Figures A3-9 supply lines to the Refueling procedures will ensure that hoses through A3-11. Water Purification Pumps on are connected before flood levels During Mode 5 and 6 with SGs AB el. 669. reach the connection.

unavailable, suction will be

• Add an isolation valves on taken from the RWST and these connection locations.

discharged through the

• Add a Storz adapter with cap intermediate pressure FLEX on branch.

pumps (staged near the RWST connection) to the primary connection point, Figure A3-12.

E-32

Maintain RCS Inventory Control PWR Portable Equipment Phase 2:

The secondary RCS connection The secondary connection All FLEX equipment and will be on the SIP Train B modification is identical to the connection points will be designed discharge line, in the SIP room. primary, except for on the SIP to meet or exceed Sequoyah This connection is used only Train B discharge. design basis SSE protection during non-flood conditions. requirements.

BAT and RWST Modifications:

For this alignment, suction will The secondary connection and Same as primary.

be taken from the BATs or BAT connection are located inside RWST and discharged through the Auxiliary Building. The the high pressure FLEX pumps Auxiliary Building is a safety to the connection points shown related structure and is protected in Attachment 3, Figure A3-6. from all external hazards except The proposed hose routing for flooding.

the secondary RCS FLEX The RWST connection will be connection and the associated seismically qualified and missile equipment can be found in protected. , Figure A3-9 through A3-11.

During Modes 5 and 6 with SGs unavailable, suction will be taken from the RWST and discharged through the intermediate pressure FLEX pumps staged near the RWST connection to the secondary connection point.

An additional RCS connection FMBMS Connection Modification All FLEX equipment and (for flood conditions only) will connection points will be designed

• Adapter and hose connection at be at the Flood Mode Boration to meet or exceed Sequoyah spool piece flange connection System (Auxiliary Boration design basis SSE protection to FMBMS System/Auxiliary Charging requirements.

System) spool piece flange RWST modifications:

This connection is located inside connection.

• Install pipe taps on RWST the Auxiliary Building. The Suction to the pump is provided supply lines to the Refueling Auxiliary Building is a safety from the RWST FLEX Water Purification Pumps on related structure and is protected connection with HP FLEX AB el. 669. from all external hazards except Pumps discharge is routed to the

• Add an isolation valves on flooding. The FMBMS Flood Mode Boration System these connection locations. connection is located above the (FMBMS) spool piece flange

• Add a Storz adapter with cap PMF.

connection. on branch.

Notes:

1. System modifications are described in the Modifications section above and are illustrated in Attachment 3.

2. N high pressure FLEX pumps will be stored in the Auxiliary Building and N high pressure FLEX pumps will be stored in the FESB. This satisfied N+1 NEI requirements.

3. Figures A3-9 through A3-11 in Attachment 3 provides the deployment routes from the staging locations for each HP FLEX Pump to the pump suction piping and to the primary and secondary connection points on the RCS connected systems.

E-33

Maintain RCS Inventory Control PWR Portable Equipment Phase 3:

Provide a general description of the coping strategies using phase 3 equipment including modifications that are proposed to maintain RCS Inventory Control. Identify methods (Low Leak RCP Seals and/or borated high pressure RCS makeup) and strategy(ies) utilized to achieve this coping time.

This section discusses RCS inventory control and subcriticality issues for conditions where SGs are available. RCS inventory control and subcriticality issues for conditions where SGs are not available are addressed in the reactor core cooling and heat removal section of this report.

Reactor level and sub-criticality is adequately maintained via the Phase 2 strategy; however, borated sources are limited. Phase 3 deployment of a unit capable of generating borated water from the water processed through the purification unit can further extend coping times with respect to RCS inventory management.

For Phase 3, Sequoyah will continue the Phase 2 coping strategies with additional assistance provided from offsite equipment/resources. Backup or alternate Phase 2 FLEX equipment will be provided by the RRC as necessary.

Sequoyah will determine where Phase 3 equipment will be staged (Open Item OI-5).

Details:

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyah's strategy aligns with the generic guidance and will consider the NSSS specific guidance once available. Finally, Sequoyah will include in procedures notification of the RRC to arrange for delivery and deployment of off-site equipment and sufficient supplies of commodities.

Identify modifications Each of the Phase 3 strategies will utilize common connections as described for the Phase 2 connections to prevent any compatibility issues with the offsite equipment.

Key Reactor Parameters List instrumentation credited or recovered for this coping evaluation.

1. CET Temperature**

2. RCS HL Temperature (Thot) if CETs not available

3. RCS CL Temperature (Tcold)*

4. RCS wide range pressure

5. Pressurizer Level

6. RVLIS (backup to Pressurizer level) - available for up to 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> for limiting flood scenario, at which point pressurizer level is available again.

7. Neutron Flux For all instruments listed above the normal power source and the long-term power source is the 125v DC Vital Battery.

• This instrumentation is only available until flood water enters the auxiliary instrument room. The potential validating indicator for Tcold is SG pressure when natural circulation is occurring. This substitution is allowed by guidance provided in Reference 16.

• • This instrumentation is only available until flood water enters the E-34

Maintain RCS Inventory Control PWR Portable Equipment Phase 3:

auxiliary instrument room (Open Item OI 26 closed). The potential validating indicator for CETs is RCS HL. This substitution is allowed by guidance provided in Reference 16.

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Deployment Conceptual Modification (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed protected to the point of use.

All FLEX equipment connection A mobile boration system would Each of the Phase 3 strategies will points will be designed to meet or enable borated water to be utilize common connections as exceed Sequoyah design basis produced using the non-borated described for the Phase 2 SSE protection requirements.

water sources that are available connections to prevent any at Sequoyah. This unit would compatibility issues with the The discharge connections will be combine the purified non- offsite equipment. identical to the ones used for borated water from the mobile Phase 2. The protection of those water purification system and connection points is described in boron with a mixing mechanism the section for Phase 2 for RCS to discharge a desired Inventory Control.

concentration of borated water which could be used to makeup to the BATs or RWST. This unit would be self-supported.

Notes: None E-35

Maintain Containment Determine Baseline coping capability with installed coping 3 modifications not including FLEX modifications, utilizing methods described in Table 3-2 of NEI 12-06:

• Containment Spray

• Hydrogen igniters (ice condenser containments only)

PWR Installed Equipment Phase 1:

Provide a general description of the coping strategies using installed equipment including modifications that are proposed to maintain containment. Identify methods (containment spray/Hydrogen igniter) and strategy(ies) utilized to achieve this coping time.

Sequoyah will perform a containment evaluation based on the boundary conditions described in Section 2 of NEI 12-06. Based on the results of this evaluation, required actions to ensure maintenance of containment integrity and required instrumentation function will be developed (Open Item OI-4)

There are no phase 1 actions required at this time that need to be addressed.

Details:

Provide a brief description Procedures and guidance to support implementation of this strategy, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify modifications N/A Key Containment List instrumentation credited for this coping evaluation.

Parameters

1. Containment Pressure*

2. Containment Temperature**

• For this instrumentation the normal power source and the long-term power source is the 125v DC Vital Battery.

• • This instrumentation is only available until flood water enters the technical support center (TSC) inverter or station battery rooms(Oprn Item OI-10).

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Notes: None 3

Coping modifications consist of modifications installed to increase initial coping time, i.e., generators to preserve vital instruments or increase operating time on battery powered equipment.

E-36

Maintain Containment PWR Portable Equipment Phase 2:

Provide a general description of the coping strategies using on-site portable equipment including modifications that are proposed to maintain containment. Identify methods (containment spray/hydrogen igniters) and strategy(ies) utilized to achieve this coping time.

Sequoyah will perform a containment evaluation based on the boundary conditions described in Section 2 of NEI 12-06. Based on the results of this evaluation, required actions to ensure maintenance of containment integrity and required instrumentation function will be developed (Open Item OI-4)

Additionally, the 480v FLEX DGSs discussed in the safety functions support section will provide power directly to the hydrogen igniter supply transformers.

The onsite 6.9 KV FLEX DGs are available to provide power to Containment Air Return Fans or Lower Compartment Coolers (LCCs) for containment temperature control, if required. Cooling water would be provided to the LCCs by the onsite LP FLEX pump feeding the ERCW system header.

Details:

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify modifications Power capability will be installed to the hydrogen igniter supply transformers.

Key Containment List instrumentation credited or recovered for this coping evaluation.

Parameters

1. Containment Pressure*

2. Containment Temperature**

• For this instrumentation the normal power source and the long-term power source are the 125v DC Vital Battery.

• • This instrumentation is only available until flood water enters the TSC inverter or station battery rooms (Open Item OI-10).

Storage / Protection of Equipment:

Describe storage / protection plan or schedule to determine storage requirements Seismic The 480v FLEX DGs will be pre-staged on the roof of the Auxiliary Building. A protection structure will be built around the DGs, which will be designed to the same Seismic Category I requirements as the Auxiliary Building. Seismic input for the design corresponds to the appropriate seismic accelerations at the roof of the Auxiliary Building.

Flooding The 480v FLEX DGs will be pre-staged on the roof of the Auxiliary Building, which is sited in a suitable location that is above the PMF and as such is not susceptible to flooding from any source.

Severe Storms with High The 480v FLEX DGs will be pre-staged on the roof of the Auxiliary Winds Building. A protection structure will be built around the DGs, which is sited in a suitable location that is protected from Nuclear Regulatory Commission (NRC) region 1 tornado, missiles, and velocities as defined in NRC Regulatory Guide 1.76 Revision 1.

E-37

Maintain Containment Snow, Ice, and Extreme Cold The 480v FLEX DGs will be pre-staged on the roof of the Auxiliary Building. A protection structure will be built around the DGs, and will be evaluated for snow, ice and extreme cold temperature effects and heating will be provided as required to assure no adverse effects on the FLEX equipment.

High Temperatures The 480v FLEX DGs will be pre-staged on the roof of the Auxiliary Building. A protection structure will be built around the DGs, and will be evaluated for high temperature effects and ventilation will be provided as required to assure no adverse effects on the FLEX equipment.

Deployment Conceptual Modification (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

The hydrogen igniters will be Diverse transfer switches will be The protection structure for the repowered by the 480v FLEX installed which directly supply the 480v FLEX DGs and the diverse DGs that will be pre-staged on the hydrogen igniter transformers. transfer switches will be designed roof of the Auxiliary Building or and installed such that each is by the 6.9KV FLEX DGs. protected from the five external Cabling will be routed from the hazards, as described in this generators to one of the diverse section.

transfer switches that will be installed.

Notes: None E-38

Maintain Containment PWR Portable Equipment Phase 3:

Provide a general description of the coping strategies using Phase 3 equipment including modifications that are proposed to maintain containment. Identify methods (containment spray/hydrogen igniters) and strategy(ies) utilized to achieve this coping time.

Sequoyah will perform a containment evaluation based on the boundary conditions described in Section 2 of NEI 12-06. Based on the results of this evaluation, required actions to ensure maintenance of containment integrity and required instrumentation function will be developed (Open Item OI-4)..

Additionally, the hydrogen igniters would continue to be repowered by the 480v FLEX DGS or 6.9KV FLEX DGs. A backup or alternate set of Phase 2 equipment will be provided by the RRC as needed.

Details:

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available. Finally, Sequoyah will include in procedures notification of the RRC to arrange for delivery and deployment of offsite equipment and sufficient supplies of commodities.

Identify modifications The same modification as Phase 2 applies for Phase 3.

Key Containment List instrumentation credited or recovered for this coping evaluation.

Parameters

1. Containment Pressure*

2. Containment Temperature**

• For this instrumentation the normal power source and the long-term power source is the 125v DC Vital Battery.

• • This instrumentation is only available until flood water enters the TSC inverter or station battery rooms. (Open ItemOI-10)

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Deployment Conceptual Modification (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

The same modification, as Phase 2 The same modification, as Phase 2 All FLEX equipment and applies for Phase 3. applies for Phase 3. connection points will be designed to meet or exceed Sequoyah design basis safe shutdown earthquake (SSE) protection requirements.

The same modification, as Phase 2 applies for Phase 3.

Notes: None E-39

Maintain Containment Maintain Spent Fuel Pool Cooling Determine Baseline coping capability with installed coping 4 modifications not including FLEX modifications, utilizing methods described in Table 3-2 of NEI 12-06:

• Makeup with Portable Injection Source PWR Installed Equipment Phase 1:

Provide a general description of the coping strategies using installed equipment including modifications that are proposed to maintain spent fuel pool cooling. Identify methods (makeup via portable injection source)and strategy(ies) utilized to achieve this coping time.

Reference 10 summarizes that there will be no volume lost from the SFP due to sloshing. Access to the SFP area as part of Phase 2 response could be challenged due to environmental conditions near the pool.

Therefore, the required action is to establish ventilation in this area and establish any equipment local to the SFP required to accomplish the coping strategies (such as the primary SFP cooling strategy discussed below). If the air environment in the SFP area requires the building to be ventilated, doors will be opened to establish air movement and venting the SFP building. For accessibility, establishing the SFP vent and any other actions required inside the fuel handling building should be completed before boil-off occurs.

Operating, pre-fuel transfer or post-fuel transfer Considering no reduction in SFP water inventory starting from nominal pool level, this results in a time when boil off decreases the water level to 10 feet above the SFP racks of approximately 29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> for an SSE seismic event with an initial bulk water temperature in the pool of 100°F. This value was calculated using the normal operating decay heat load.

Fuel in Transfer or Full Core Offload For the maximum credible heat load and an initial water temperature in the pool of 140°F, the time when boil off decreases the water level to 10 feet above the SFP racks is approximately 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> as summarized in Reference 10.

In order to keep the pool at a constant level of coolant (thus covering the top of the spent fuel), the low pressure FLEX pump will pressurize the ERCW headers to provide makeup to prevent a decrease in the level of the SFP.

Details:

Provide a brief description Procedures and guidance to support implementation of this strategy, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify modifications N/A Key SFP Parameter The implementation of this parameter will align with the requirements of by NRC Order EA 12-051.

This instrument will have initial local battery power, with the capability to be powered from the 480v FLEX DGs..

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Notes:

4 Coping modifications consist of modifications installed to increase initial coping time, i.e., generators to preserve vital instruments or increase operating time on battery powered equipment.

E-40

Maintain Spent Fuel Pool Cooling PWR Portable Equipment Phase 2:

Provide a general description of the coping strategies using on-site portable equipment including modifications that are proposed to maintain spent fuel pool cooling. Identify methods (makeup via portable injection source)and strategy(ies) utilized to achieve this coping time.

The transition to Phase 2 strategies will be as the inventory in the SFP slowly declines due to boiling. SFP cooling through makeup and spray will be provided by using a FLEX pump to inject coolant directly into the pool, into existing SFP cooling piping, or spray the coolant into the pool using portable FLEX spray nozzles.

The Spent Fuel Pool Cooling Pump(s) may be energized utilizing the 6.9 KV FLEX DGs to provide SFP cooling.

Operating, pre-fuel transfer or post-fuel transfer Considering no reduction in SFP water inventory starting from nominal pool level, this results in a time when boil off decreases the water level to 10 feet above the SFP racks of approximately 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br /> for an SSE seismic event with an initial bulk water temperature in the pool of 100°F, as summarized in Reference 10.

This value was calculated using the normal operating decay heat load.

Fuel in Transfer or Full Core Offload For the maximum credible heat load and an initial water temperature in the pool of 140°F, the time when boil off decreases the water level to 10 feet above the SFP racks is approximately 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />, as summarized in Reference 10.

To provide an unlimited supply of water for SFP makeup during Phase 2, a LP FLEX pumps will be used to pressurize the ERCW headers which can then be used for makeup to the SFP FLEX mitigation strategies.

For restoration of SFP cooling of the SFP, Sequoyah intends to repower one train of normal pool cooling equipment. This will include the use of the LP FLEX pumps on site to provide flow to the CCS heat exchanger and the onsite 6.9 KV FLEX DGs to repower both the CCS and SFP cooling pumps.

The primary SFP makeup flow method is from the ERCW header connections through a hose to a new connection added to the SFP makeup line from the Demineralized Water System (DWS). This alignment provides makeup control when the refueling floor is not accessible. The secondary SFP makeup flow method is from the ERCW header valves located on the refueling floor through hoses directly to the open SFP. Both connections can be used during both flood and non-flood conditions.

Sequoyah will provide portable monitor (fire-fighting) flow nozzle capability based on a flow of 500 gpm, which equals the FLEX requirement to provide 250 gpm of spray flow per unit to the spent fuel pool.

Details:

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify modifications List modifications

1. All modifications described for other functions to allow suction to be taken from the AFWST, RWST, or other surviving tanks will E-41

Maintain Spent Fuel Pool Cooling apply to this function.

2. The primary connection will require a new tee, with an upstream isolation valve, a branch line and quick connect capability, to be installed on the DWS piping leading to the SFP.

3. The secondary connections with Storz fittings will be installed at two ERCW supply valves on the SFP elevation to supply direct makeup or spray flow to the pool.

4. Modifications required to pressurize the ERCW headers are described under Phase 2 Maintain Core Cooling and Heat Removal Key SFP Parameter The implementation of this parameter will align with the requirements of by NRC Order EA 12-051.

This instrument will have initial local battery power, with the capability to be powered from the 480v FLEX DGs.

Storage / Protection of Equipment:

Describe storage / protection plan or schedule to determine storage requirements Seismic Portable equipment required to implement this FLEX strategy will be maintained in the FESB, which will be designed for seismic loading in excess of the minimum requirements ASCE 7-10. The design of the FESB provides a minimum HCLPF of 2x SSE. The 480v FLEX DGs. are installed on the AB roof in a protected enclosure.

Flooding Portable equipment required to implement this FLEX strategy will be maintained in the FESB, which is designed to meet or exceed the licensing basis high wind hazard for Sequoyah. The 480v FLEX DGs, are installed on the AB roof in a protected enclosure.

Severe Storms with High Portable equipment required to implement this FLEX strategy will be Winds maintained in the FESB, which is sited in a suitable location that is protected from NRC region 1 tornado, missiles, and velocities as defined in NRC Regulatory Guide 1.76 coupled with 360 mph wind speeds (Reference 4, Section 3.8.1.3). The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

Snow, Ice, and Extreme Cold The FESB will be evaluated for snow, ice and extreme cold temperature effects and heating will be provided as required to assure no adverse effects on the FLEX equipment. The FESB will have a standalone HVAC system.

The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

High Temperatures The FESB will be evaluated for high temperature effects and ventilation will be provided as required to assure no adverse effects on the FLEX equipment. The FESB will have a standalone HVAC system. The 480v FLEX DGs are installed on the AB roof in a protected enclosure.

E-42

Maintain Spent Fuel Pool Cooling Deployment Conceptual Design (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

The primary SFP connection will Primary Connection Modification All FLEX equipment and be to the DWS makeup line in the connection points will be designed

• A tee will be added to the auxiliary building. This strategy to meet or exceed Sequoyah DWS makeup line to the SFP can be implemented in non-flood design basis SSE protection conditions.

• An isolation valve will be requirements.

added to the main line FLEX hose will be routed from upstream of the connection. The connection point is on the this location, across the floor to

• An isolation valve will be exterior of the Auxiliary Building, the ERCW FLEX connections. added to the new branch. which is seismically qualified and

• Storz cap/adapter will be missile protected. Hose routing to An alternate supply involves added to the new branch. the secondary connection will be routing fire hose from either the performed before flood conditions RWST, CST, or other surviving CST, RWST, ERCW or other make the area inaccessible and a tanks to the SFP floor. This surviving tanks Modifications hose throttle valve will be strategy is for non-flood The modification for these sources provided above the PMF.

conditions.

would be the same as for the Connections to the ERCW, CST, The proposed hose routing for the primary method for this function.

RWST and other surviving tanks primary connection and the In addition, the modification to have been described in Phase 2 associated equipment can be found add a hose connection to the Reactor Core Cooling and Heat in Attachment 3, Figure A3-17. ERCW FLEX connections Removal.

The system connection points can described in the Reactor Core be found in Attachment 3, Figure Cooling and Heat Removal section A3-14. also applies to this case due to the ERCW connections can be found location of the connection point.

in Attachment 3, Figure A3-13.

The secondary method is flow Secondary Method Modification All FLEX equipment and from the ERCW headers at two connection points will be designed An adapter with hose connection locations using adapters and hose to meet or exceed Sequoyah will be installed at the ERCW connections. This strategy can be design basis SSE protection supply valve to the CCS surge implemented in non-flood requirements.

tank flood condition spool piece.

conditions.

The secondary connection is in the ERCW Modifications The proposed hose routing for the Auxiliary Building, which is secondary method and the The same modifications required seismically qualified and missile associated equipment can be found to pressurize ERCW headers are protected. The secondary in Attachment 3, Figure A3-16. described under Phase 2 Maintain connection is above the PMF.

Core Cooling and Heat Removal.

Note that SFP spray would be Protection of CST, RWST, and routed in an identical manner; CST, RWST and other surviving other surviving tanks is described however, the end of the hose tanks Modifications: under Phase 2 Maintain Core would have the spray nozzle Cooling and Heat Removal.

installed. All modifications described for E-43

Maintain Spent Fuel Pool Cooling An alternate supply to the SFP can other functions to allow suction to be provided using transfer pumps be taken from the CST, RWST, or from the RWST, CST or other other surviving tanks will apply to surviving tanks by routing hoses this function.

to the SFP elevation. This strategy is for non-flood conditions only.

ERCW connections can be found in Attachment 3, Figures A3-13.

Notes:

1. System modifications are described in the Modifications section above and are illustrated in Attachment 3.

2. Figures A3-16 and A3-17 in Attachment 3 provides the hose routes for the SFP makeup strategies.

E-44

Maintain Spent Fuel Pool Cooling PWR Portable Equipment Phase 3:

Provide a general description of the coping strategies using Phase 3 equipment including modifications that are proposed to maintain spent fuel pool cooling. Identify methods (makeup via portable injection source) and strategy(ies) utilized to achieve this coping time.

Details:

The strategies described for Phase 2 can continue as long as there is sufficient inventory available to feed the strategies. As mentioned for the Reactor Core Cooling and Heat Removal function, a mobile water purification unit will be received from the RRC to provide continued purified water to support this function.

Additionally, as mentioned for the Maintain RCS Inventory Control function, a mobile boration unit will be received from the RRC to provide continued borated coolant to support this function, if required.

Sequoyah will determine where Phase 3 equipment will be staged (Open Item OI-5).

Also, a backup or alternate set of Phase 2 equipment will be provided by the RRC as needed.

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies /

including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available. Finally, Sequoyah will include in procedures notification of the RRC to arrange for delivery and deployment of offsite equipment and sufficient supplies of commodities.

Identify modifications N/A Key SFP Parameter The implementation of this parameter will align with the requirements of by NRC Order EA 12-051.

This instrument will have initial local battery power, with the capability to be powered from the 480v FLEX DGs Deployment Conceptual Design (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

The description for the mobile The description for the mobile The description for the mobile boration unit and water boration unit and water boration unit and water purification system will be the purification system will be the purification system will be the same as was mentioned for the same as was mentioned for the same as was mentioned for the other functions. other functions. other functions.

Notes: None E-45

Safety Functions Support Determine Baseline coping capability with installed coping 5 modifications not including FLEX modifications.

PWR Installed Equipment Phase 1 Provide a general description of the coping strategies using installed equipment including station modifications that are proposed to maintain and/or support safety functions. Identify methods and strategy(ies) utilized to achieve coping times.

Sequoyah will rely on existing installed 125v DC Vital Batteries to power key instrumentation and emergency lighting. To extend run time before recharging is possible; a load-shedding procedure will be implemented with the first phase of load shed complete by 45 minutes and the extended load shed complete by 90 minutes. A battery coping calculation will be performed to demonstrate that the battery coping time is 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (OI 25).

Preliminary analysis using conservative heat loads in the Auxiliary and Control Buildings has shown that installed equipment credited for mitigation response will remain available. In addition, accessibility of these areas for required actions is acceptable.

Details:

Provide a brief description Confirm that procedure/guidance exists or will be developed to support of Procedures / Strategies / implementation.

Guidelines Procedures and guidance to support deployment and implementation, including interfaces to EOPs, special event procedures, abnormal event procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyah's strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify modifications List modifications and describe how they support coping time.

N/A Key Parameters List instrumentation credited for this coping evaluation phase.

1. DC Bus Voltage For all instruments listed above the normal power source and the long-term power source are the 125v DC Vital Battery Systems.

Notes: None 1

Coping modifications consist of modifications installed to increase initial coping time, i.e., generators to preserve vital instruments or increase operating time on battery powered equipment.

E-46

Safety Functions Support PWR Portable Equipment Phase 2 Provide a general description of the coping strategies using on-site portable equipment including station modifications that are proposed to maintain and/or support safety functions. Identify methods and strategy(ies) utilized to achieve coping times.

The primary electrical need during Phase 2 is DC power for critical instrumentation. This will be accomplished by energizing the support power system and energizing battery chargers on both A and B trains in both Units 1 and 2.

The on-site 480v FLEX DGS are pre-staged to provide power to the 125v DC Vital Battery and 120v AC Vital Instrument Power Systems. These generators will be pre-staged on the Auxiliary Building roof and will be protected from the external hazards with an adequate supply of fuel for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of operation. The 480v FLEX DGs will be connected to the battery chargers to power the DC and AC Vital Instrument Power System.

Additionally, the onsite 6.9 KV FLEX DGs are pre-staged to provide power to the existing 6.9 kv Shutdown Power System. The 6.9 KV FLEX DGs may also serve as an alternative power source for the loads supplied by the on-site 480v FLEX DGS. Further analysis will be performed to determine the required timeline for this alternate strategy (Open Item OI-24). The 6.9 KV FLEX DGs will be staged in the FESB and protected from the external hazards discussed in this document.

Details:

Provide a brief description Confirm that procedure/guidance exists or will be developed to support of Procedures / Strategies / implementation with a description of the procedure / strategy / guideline.

Guidelines Procedures and guidance to support deployment and implementation, including interfaces to EOPs, special event procedures, abnormal event procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyah's strategy aligns with the generic guidance and will consider the NSSS specific guidance once available.

Identify modifications For the 480v FLEX DGS, two fused distribution panels will be used to provide power to the supplied loads. Each fuse panel provides connections to two Vital Battery chargers and one train of hydrogen igniter transfer switches for each unit. Each fuse distribution panel will have a connection to 480v AC distribution to close Cold Leg Accumulator Isolation valves during cooldown.

Fuel for the 480v FLEX DGs will be provided by the installed DG 7-day tanks. Fuel lines will be installed between the 7-day fuel tanks mounted under the DG Building and Auxiliary Building roof to provide fuel to the 480v FLEX DGs with a fuel transfer pump.

To connect the existing 6.9 kv Shutdown Power System to the 6.9 KV FLEX DGs during FLEX operation, the connection to the existing safety-related DG circuit is opened and the circuits to the 6.9 KV FLEX DGs are closed by operating the existing interlocked transfer switches 1A-A, 1B-B, 2A-A, or 2B-B. This will be done under administrative controls, ensuring that a no-load condition exists on the load side of the transfer switches.

The permanently installed electrical connection points for the 6.9 KV FLEX E-47

Safety Functions Support PWR Portable Equipment Phase 2 DGs are from the DGs integral output connection panel through conduits within the FESB to underground conduits located on the outside of the FESB wall. One 6.9 KV FLEX DGs will be assigned to Train A on both units and the second 6.9 KV FLEX DGs will be assigned to Train B of both units.

The conduits will meet seismic Class I requirements for safety related and quality-related structures. Actual mechanical and electrical connections to the presently installed safety related DG equipment shall meet safety related requirements at the interfaces.

Refueling of the 6.9 KV FLEX DGs will be accomplished using a separate fuel transfer pump dedicated for the purpose of transferring fuel from the 7-day tanks to the 6.9 KV FLEX DGs fuel oil day tanks.

Key Parameters List instrumentation credited or recovered for this coping evaluation.

• DC Bus Voltage For the instrument listed above the normal power source and the long-term power source are the 125v DC Vital Battery.

Sequoyah will develop procedures to read this instrumentation locally, where applicable, using a portable instrument as required by Section 5.3.3 of NEI 12-06.

Storage / Protection of Equipment Describe storage / protection plan or schedule to determine storage requirements Seismic Equipment for this function will either be stored or pre-staged in the FESB, in the Auxiliary Building, Intake Pumping Station or on the Auxiliary Building roof. The protection of FLEX equipment for this hazard is addressed for each of these locations in the Reactor Core Cooling and Heat Removal and Maintain RCS Inventory Control sections.

Flooding Equipment for this function will either be stored or pre-staged in the FESB, Note: if stored below current flood level, in the Auxiliary Building, Intake Pumping Station or on the Auxiliary then ensure procedures exist to move Building roof. The protection of FLEX equipment for this hazard is equipment prior to exceeding flood level. addressed for each of these locations in the Reactor Core Cooling and Heat Removal and Maintain RCS Inventory Control sections.

Severe Storms with High Equipment for this function will either be stored or pre-staged in the FESB, Winds in the Auxiliary Building, Intake Pumping Station or on the Auxiliary Building roof. The protection of FLEX equipment for this hazard is addressed for each of these locations in the Reactor Core Cooling and Heat Removal and Maintain RCS Inventory Control sections.

Snow, Ice, and Extreme Cold Equipment for this function will either be stored or pre-staged in the FESB, in the Auxiliary Building, Intake Pumping Station or on the Auxiliary Building roof. The protection of FLEX equipment for this hazard is addressed for each of these locations in the Reactor Core Cooling and Heat Removal and Maintain RCS Inventory Control sections.

High Temperatures Equipment for this function will either be stored or pre-staged in the FESB, in the Auxiliary Building, Intake Pumping Station or on the Auxiliary Building roof. The protection of FLEX equipment for this hazard is E-48

Safety Functions Support PWR Portable Equipment Phase 2 addressed for each of these locations in the Reactor Core Cooling and Heat Removal and Maintain RCS Inventory Control sections.

Deployment Conceptual Design (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

The strategy for this function is The modifications for this function The protection structure for the described above in the Identify are described in the Identify 480v FLEX DGs will be designed Modifications section. Modifications section. and installed such that each is protected from the five external hazards, as described in this section. The fuse distribution panels for the 480v FLEX DGs will be located inside the Auxiliary Building which will provide protection from the external hazards, as described in this section.

Notes: None E-49

Safety Functions Support PWR Portable Equipment Phase 3 Provide a general description of the coping strategies using Phase 3 equipment including modifications that are proposed to maintain and/or support safety functions. Identify methods and strategy(ies) utilized to achieve coping times.

A backup or alternate set of Phase 2 equipment will be provided by the RRC, as needed. Sequoyah will determine where Phase 3 equipment will be staged (Open Item OI-5).

Details:

Provide a brief description Procedures and guidance to support deployment and implementation, of Procedures / Strategies / including interfaces to EOPs, special event procedures, abnormal event Guidelines procedures, and system operating procedures, will be developed in accordance with NEI 12-06, Rev. 0, Section 11.4. Further, the PWROG has developed generic guidance, and Sequoyahs strategy aligns with the generic guidance and will consider the NSSS specific guidance once available. Finally, Sequoyah will include notification of the RRC in plant procedures to arrange for delivery and deployment of off-site equipment and sufficient supplies of commodities.

Identify modifications N/A Key Parameters No additional instrumentation is required to support the Phase 3 safety function support.

Deployment Conceptual Design (Attachment 3 contains Conceptual Sketches)

Strategy Modifications Protection of connections Identify Strategy including how Identify modifications Identify how the connection is the equipment will be deployed to protected the point of use.

A backup or alternate set of Phase Each of the Phase 3 strategies will There are no connection points for 2 equipment will be provided by utilize common connections as this strategy. All equipment will the RRC, as needed. described for the Phase 2 be provided by offsite resources.

connections to prevent any compatibility issues with the offsite equipment.

Notes: None E-50

PWR Portable Equipment Phase 2 Use and (potential / flexibility) diverse uses Performance Criteria 6 Maintenance List portable equipment Core Containment SFP Instrumentation Accessibility Maintenance / PM requirements Two Medium Voltage Diesel X X X X X *6900 V Will follow EPRI template Generator 3 MWe DG requirements Two Low Voltage Diesel X X X X X 480v AC Will follow EPRI template Generators 225 kva requirements Three (Dominator) Low X X X 5000 gpm Will follow EPRI template Pressure FLEX Pumps 350 ft. TDH requirements (Pressurizes ERCW Diesel Driven Headers)

Three (Triton) Floating X X X 5000 gpm Will follow EPRI template Booster Pumps (Supplies 50 ft. lift requirements Low Pressure FLEX Pump) Diesel Driven Three Intermediate Pressure X 135 gpm Will follow EPRI template FLEX Pumps (Core Cooling 942 ft. total dynamic head requirements Makeup) (TDH)

Four High Pressure FLEX X 20 gpm Will follow EPRI template Pumps (RCS) 3561 ft. TDH requirements 480v AC Two Water Transfer pumps X X 500 gpm Will follow EPRI template 247 ft. TDH requirements Diesel Driven Two SFP Spray Nozzles X 250 gpm Will follow EPRI template requirements 6

Performance criteria of FLEX equipment is conservative and was determined during conceptual design as a basis for the selection of required FLEX equipment.

The criteria will be re-analyzed during the detailed design phase (OI 7).

E-51

PWR Portable Equipment Phase 2 Use and (potential / flexibility) diverse uses Performance Criteria 6 Maintenance List portable equipment Core Containment SFP Instrumentation Accessibility Maintenance / PM requirements Two Tow Vehicles X X X X Capable of on-site Will follow EPRI template transport of 14,000 Gross requirements Vehicle Weight (GVW) trailer Fuel Transfer Equipment X X X X X Will follow EPRI template 500 gallons requirements

• Two Fuel Tankers Minimum

• Two Diesel Fuel 200 gpm Transfer Pumps Diesel Driven Debris Clearing Equipment X Capable of clearing trees, Will follow EPRI template light poles, construction requirements Caterpillar Skid Steer materials and miscellaneous debris E-52

PWR Portable Equipment Phase 3 Use and (potential / flexibility) diverse uses Performance Criteria 7 Notes List portable equipment Core Containment SFP Instrumentation Accessibility Medium Voltage Diesel X X X X X *6900V Will follow EPRI template Generator Backup 3 MWe DGs requirements Low Voltage Diesel Generators X X X X X 480v AC Will follow EPRI template Backup 225 kva requirements Three (Dominator) Low X X X 5000 gpm Will follow EPRI template Pressure FLEX Pumps 350 ft. TDH requirements (Pressurizes ERCW Headers) Diesel Driven Three (Triton) Floating Booster X X X 5000 gpm Will follow EPRI template Pumps (Supplies Low Pressure 50 ft. lift requirements FLEX Pump) Diesel Driven Intermediate Pressure FLEX X X 135 gpm Will follow EPRI template Pumps (Core Cooling Backup) 942 ft. TDH requirements Pump High Pressure FLEX Pump X 20 gpm Will follow EPRI template Backup 3561 ft. TDH requirements 480v AC Water Transfer Pump Backup X X 500 gpm Will follow EPRI template 247 TDH requirements Diesel Driven 7

Performance criteria of FLEX equipment is conservative and was determined during conceptual design as a basis for the selection of required FLEX equipment. The criteria will be re-analyzed during the detailed design phase (OI 7).

E-53

PWR Portable Equipment Phase 3 Use and (potential / flexibility) diverse uses Performance Criteria 7 Notes List portable equipment Core Containment SFP Instrumentation Accessibility Fuel Transfer Equipment X X X X X Will follow EPRI template

• Two Fuel Tankers 500 gallons requirements Minimum

• Two Diesel Fuel Transfer Pumps 200 gpm Diesel Driven Mobile Boration Unit X X Open Item OI-9 Supplied by RRC Mobile Water Purification Unit X X Open Item OI-9 Supplied by RRC E-54

Phase 3 Response Equipment/Commodities Item Notes Radiation Protection Equipment

• Survey instruments

• Dosimetry

• Off-site monitoring/sampling

• Radiological counting equipment

• Radiation protection supplies

• Equipment decontamination supplies

• Respiratory protection

• Portable Meteorological (MET) Towers Commodities

• Food o Meals ready to eat (MRE) o Microwaveable Meals

• Potable water Fuel Requirements

• Diesel Fuel Heavy Equipment

• Transportation equipment o 4 wheel drive tow vehicle

• Debris clearing equipment Communications Equipment

• Satellite Phones

• Portable Radios Portable Interior Lighting

• Flashlights

• Headlamps

• Batteries Portable Exterior Lighting

• Diesel generator powered light units E-55

References

1. NRC EA-12-049, Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, March 12, 2012. [ADAMS Accession Number ML12054A735]

2. NEI 12-06, Revision 0, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, August 2012.

3. NRC JLD-ISG-2012-01, Revision 0, Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, August 2012.

4. Sequoyah Nuclear Plant Updated Final Safety Analysis Report (UFSAR), Amendment No.

23.

5. LAR SQN-TS-12-02, Application to Revise Sequoyah Nuclear Plant Units 1 and 2 Updated Final Safety Analysis Report Regarding Changes to Hydrologic Analysis, August 10, 2012 (Accession No. ML12226A561).

6. Not Used.

7. WCAP-17601-P, Revision 1, Reactor Coolant System Response to the Extended Loss of AC Power Event for Westinghouse, Combustion Engineering, and Babcock & Wilcox NSSS Designs, PWROG Project PA-ASC-0916, January 2013.

8. Not used.

9. TVA Drawings

a. 46W501-2, Revision 2, Architectural Plan El 685.0 & 690.0.

b. 46W501-3, Revision 4, Architectural Plan El 706.0 & 714.0.

c. 46W501-4, Revision 0, Architectural Plan El 732.0 & 734.0.

d. 46W501-5, Revision 3, Architectural Plan El 749.0 & 759.0.

e. 47W200-1, Revision 2, Equipment Plans - Roof

f. 10N200-1, Revision F, General Plan.

10. TR-FSE-13-13, Revision 0, Sequoyah Integrated Plan, February 2013.

11. TR-FSE-13-1, Revision 2, Watts Bar Integrated Plan, February 2013.

12. Task Interface Agreement (TIA) 2004-04, "Acceptability of Proceduralized Departures from Technical Specifications (TSs) Requirements at the Surry Power Station," (TAC Nos.

MC4331 and MC4332)," dated September 12, 2006. [Accession No. ML060590273]

13. OG-12-482, Revision 0, Transmittal of PA-PSC-0965 Core Team PWROG Core Cooling Management Interim Position Paper, November, 2012.

14. FLEX Implementation HVAC Analysis Impact Study, Project No. 12938-012

15. Not Used.

16. OG-12-515, Transmittal of Final Generic PWROG FLEX Support Guidelines and Interfaces (Controlling Procedure Interface and Recommended Instruments) from PA-PSC-0965, Revision 0, December 2012.

17. ECA-0.0, Revision 26, Loss of All AC Power.

18. EA-250-1, Revision 16, Load Shed of Vital Loads After Station Blackout.

19. Sequoyah White Paper Liquification of Haul Routes for FLEX E-56

20. Westinghouse Calculation Note, CN-SEE-II-13-26, Revision 0, Sequoyah Unit 1 and Unit 2 Reactor Coolant System FLEX Evaluation with Standard Reactor Coolant Pump Seals.

21. Westinghouse Calculation Note, CN-SEE-II-12-20, Revision 2, Supporting Chemistry Calculations for Alternate Cooling Source Usage during Extended Loss of All A.C. Power at Watts Bar Nuclear Units 1 and 2.

22. Westinghouse Calculation Note, CN-SEE-II-12-20, Revision 2, Supporting Chemistry Calculations for Alternate Cooling Source Usage during Extended Loss of All A.C. Power at Watts Bar Nuclear Units 1 and 2.

23. Calculation time to core boil

24. EWR 11-LMN-003-038 Rev1 TDAFWP suction pressure versus CST level and available ERCW volume.

25. Westinghouse LTR-LIS-14-79, Revision 0, Generic Information to Support Requests for Additional Information in USNRC Reviews of FLEX Overall Integrated Plans with Regard to Reflux Cooling and Boron Mixing for PA-ASC-1197 E-57

Open Items Open item Description Status Notes Number The current condensate storage tank (CST) is a non-seismic tank that is not missile protected. The site is currently pursuing A contract has been awarded two options; the qualification and for the new Auxiliary 1 hardening of the existing CST or the Started Feedwater Supply Tank construction of a new seismically qualified (AFWST) and for tie in to and missile protected CST. One of these existing plant piping.

options must be completed before the volume of the CST can be credited.

Liquefaction of haul routes for FLEX will 2 Closed Ref 19 be analyzed.

No detailed analysis has been provided regarding initial FLEX fuel supplies to determine a need time for access to 7 day tank supplies or resupply of the 7 day Fuel consumption tanks. It is assumed that each FLEX spreadsheet completed to 3 component is stored with a minimum Closed show that fuel supply will supply of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of fuel at constant last seven days.

operation. This assumption will need to be assessed once all FLEX equipment has been purchased and equipment specifications are known.

No need time has been identified for action to protect containment. This includes actions to mitigate pressurization of containment due to steaming when reactor coolant system (RCS) vent paths MAAP Analysis due in 4 Open have been established or actions to spring of 2014 mitigate temperature effects associated with equipment survivability. An evaluation will be provided to prove indefinite containment coping.

The Phase 3 equipment staging area has Areas are identified and will 5 not been determined. Closed be included with the Regional Response Center (RRC) playbook.

A strategy for clearing and removing Debris removal equipment 6 debris will be determined. Closed is identified and storage determined E-58

Open item Description Status Notes Number A thorough analysis of the makeup flow rate requirements and other equipment Calculation to be complete 7 Started characteristics will be finalized during the by spring of 2014 detailed design phase of FLEX.

The need time for spent fuel pool (SFP) cooling actions (deployment of hose, venting, and alignment of makeup) was determined using worst case heat loads. CN-CDME-13-24 8 This item will continue to be assessed and Closed Westinghouse Calculation later action times may be acceptable. Note that the timing for this step during an outage is different, but resources will be available to complete the required actions.

Functional requirements for each of the Phase 3 strategies, equipment and 9 components will be completed at a later Started time and will be provided in the six month updates to the February 28, 2013 submittal.

Containment temperature instrumentation is only available until flood waters enter 10 the technical support center (TSC) inverter Started or station battery rooms. A method to monitor containment temperature, post-flood, will be developed.

The heating, ventilation and air Calculation to be complete 11 conditioning (HVAC) analysis is Open in April 2014 preliminary, and has not been finalized.

Verify ability to deploy FLEX equipment Demonstration prior to to provide core cooling in Modes 5 and 6 implementation of the order 12 with steam generators (SGs) unavailable. Closed and included as part of the FLEX strategy (Reference 20)

An evaluation of the impact of FLEX response actions on design basis flood This has not been completed mode preparations will be performed. since the latest revision of 13 This evaluation will include the potential Open the AOP N.03 along with for extended preparation time for FLEX. FLEX strategies.

Changes which affect the Integrated Plan will be included in the six month update.

E-59

Open item Description Status Notes Number Perform an alternate cooling source evaluation. The purpose of this analysis is FLEX strategies have both 14 to examine options to utilize alternate Complete primary and secondary water sources to provide continuous cooling sources identified.

sources of water to maintain key safety functions.

Perform conceptual hydraulic performance Open 15 analyses. The purpose of this analysis is to conservatively evaluate hydraulic performance of FLEX systems.

Develop a mechanical conceptual design Open report. The purpose of this report is to 16 summarize the mechanical conceptual design of the FLEX strategies and identify any required modifications.

Perform an electrical conceptual design Open report. The purpose of this report is to 17 summarize the electrical conceptual design of the FLEX strategies and identify any required modifications.

Perform an RCS makeup analysis. The Open 18 purpose of this analysis is to define FLEX RCS inventory and shutdown margin for Sequoyah.

Perform an SFP evaluation. The purpose Open 19 of this analysis is to evaluate the impact of sloshing and time-to-boil in the SFP after an earthquake.

Perform a timing and deployment Open evaluation. The purpose of this analysis is 20 to summarize the FLEX timeline for Sequoyah, identify time constraints and provide for the safety function needs.

Develop a programmatic control report. Open 21 The purpose of this report is to summarize the need to implement programmatic control of the FLEX program.

E-60

Open item Description Status Notes Number Evaluate the existing extreme hazard Open analysis and planned Near-Term Task 22 Force (NTTF) Tier 1 activities on FLEX strategies to summarize on-going industry activities and the potential to impact the developed FLEX strategies.

The time at which the Forebay volume Open depletes needs to be evaluated to determine the time at which replenishment is required. Based on Reference 10 there is 1,640,000 gallons available in the Forebay. Based on the alternate cooling 23 source evaluation, approximately 640,000 gallons are required at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> post ELAP. Therefore, it is expected the Forebay volume will supply suction to the TDAFWP for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following the ELAP event and replenishment will be required during Phase 3.

Further analysis will be performed to Open determine the required timeline for 24 implementing the 6.9 KV FLEX DGs as an alternate power source for the loads supplied by the 480v FLEX DGs.

Complete battery calculations to document Vital Battery life of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> after loss of 25 all AC. A battery calculation has been Open completed for WBN which is of similar design.

The CETs are only available until water 26 enters the auxiliary instrument room. A CETs will not be required Closed method to monitor CET, post flood, will be for flood event.

evaluated and developed, if required.

Strategies to address extreme cold Initial RWST Technical conditions on the refueling water storage 27 Specifications temperature tank (RWST) and/or boric acid tanks Closed requirements ensure that (BATs), including potential need to five hours is not challenged.

reenergize heaters have not been finalized.

E-61

Open item Description Status Notes Number Establish a contract with the SAFER team Agreement with Regional 28 in accordance with the requirements of Closed Response Center (RRC) is Section 12 of Reference 2. in place E-62

Acronyms AB auxiliary building ABMT auxiliary boration makeup tank ac alternating current ACR auxiliary control room ACS alternate cooling source AFW auxiliary feedwater AFWST auxiliary feedwater supply tank AOP abnormal operating procedure AOV air-operated valve APM available physical margin ARV atmospheric relief valve AUO assistant unit operator BAT boric acid tank BCS backup control station BDB beyond-design-basis BDBEE beyond-design-basis external events CCS component cooling system CCW condenser circulating water CFR Code of Federal Regulations CFT core flood tank CLA cold leg accumulator CLB cold leg break CST condensate storage tank CVCS chemical and volume control system CWST cask washdown storage tank DBE design basis event DBFL design basis flood level dc direct current DG diesel generator DGB diesel generator building DWHT demineralized water head tank DWS demineralized water system DWST demineralized water storage tank EDG emergency diesel generator EDMG extreme damage mitigation guideline EFW emergency feedwater ELAP extended loss of ac power EOI emergency operating instruction EOP emergency operating procedure EPRI Electric Power Research Institute ERCW essential raw cooling water ERO Emergency Response Organization ESF engineered safety feature FESB FLEX equipment storage building FLEX Flexible and Diverse Coping Mitigation Strategies FMBMS flood mode boration makeup system FSG FLEX support guideline FSI FLEX support instructions HCLPF high confidence of low probability failure E-63

HPFP high pressure fire protection HP FLEX Pump High Pressure (HP) FLEX Pumps HVAC heating, ventilation, and air conditioning IER Industry Event Report INPO Institute of Nuclear Power Operations IP FLEX Pump Intermediate Pressure (IP) FLEX Pumps IPS intake pumping station ISG Interim Staff Guidance LCV level control valve LOCA loss-of-coolant accident LOOP loss of offsite power LUHS loss of normal access to the ultimate heat sink MCC Motor Control Center MCR main control room MDAFWP motor driven auxiliary feedwater pump MOV motor operated valve MRE meals ready to eat MSL mean sea level NEI Nuclear Energy Institute NPSH net positive suction head NRC Nuclear Regulatory Commission NSSS nuclear steam supply system NTTF Near-Term Task Force OBE Operating Basis Earthquake PORV power operated relief valve PMF probable maximum flood PMP probable maximum precipitation PWR pressurized water reactor PWROG Pressurized Water Reactor Group Owners Group PWST primary water storage tank QR quality related RCP reactor coolant pump RCS reactor coolant system RHR residual heat removal RRC Regional Response Center RSO River Systems Operations RWST refueling water storage tank RWT raw water tank SAFER Strategic Alliance for FLEX Emergency Response SAMG severe accident management guideline SBO station blackout SDB shutdown board SFP spent fuel pool SG steam generator SIP safety injection pump SIS safety injection system SIT safety injection tank SR safety related S/RV safety/relieve valve SSC systems, structures and components SSE safe shutdown earthquake E-64

TD turbine-driven TDH total dynamic head TDAFWP turbine driven auxiliary feedwater pump TOAF top of active fuel TSC technical support center TVA Tennessee Valley Authority UFSAR updated final safety analysis report UHS ultimate heat sink E-65

Attachment 1A Sequence of Events Timeline Non-Flood Event New ELAP Elapsed Time Task Action time from Event Action Duration Remarks / Applicability Item constraint Initiation (T-0) (hours)

Y/N 0 Event Starts NA NA Plant @100% power 0 SBO N NA ECA-0.0 (Reference 17)

Complete Initial Load Shed (Station Blackout Sheds 125v DC Vital Loads to ensure 4 1 0 N Within .75 (SBO) Load Shed) hour coping.

hours of T-0 ELAP entry can be verified by control room staff and it is validated that the Emergency Diesel Generators (EDGs)

Within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Within 1 2 Declare ELAP N are not available. This declaration needs of T-0 hour of T-0 to occur within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from T-0 to provide operators with guidance to perform ELAP actions.

Completed with 90 minutes (1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) from T-0. This ensures an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> coping Complete time for the 125v DC Vital Batteries.

Extended Load Shed (Extended Station 3 .75 hour8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> N Within 1.5 This ensures the 125v DC Vital Battery Blackout (ESBO) Load Shed) hours of T-0 chargers loading is less than the load limit on the chargers (ensures charging of the batteries).

EA1-1

New ELAP Elapsed Time Task Action time from Event Action Duration Remarks / Applicability Item constraint Initiation (T-0) (hours)

Y/N Sequoyah is developing a post event damage assessment procedure. The damage assessment will evaluate and document the condition of plant systems, structures and components (SSCs) after an ELAP event. The assessment will be Damage Assessment and Flex consistent with guidelines contained in 4 .5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> supplement 5 of reference 16.

Equipment Staging FLEX equipment staging locations and access routes will be a priority for the damage assessment. This assessment will facilitate debris removal, if required, to support FLEX equipment staging. (OI 6)

Staged and aligned to take suction from the intake channel and discharge routed Stage and align Low Pressure (LP) 5 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Y 4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to the Essential Raw Cooling Water FLEX pumps (ERCW) FLEX connections at the Intake Pumping Station (IPS).

This provides charging current to the 125v DC Vital Batteries and ensures Align and place in service the 225kva 125v DC Vital Battery power (control) 6 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 480v AC Diesel Generators (DG) and through the Vital inverters 120v AC Vital Instrument Power (instrument indication).

EA1-2

New ELAP Elapsed Time Task Action time from Event Action Duration Remarks / Applicability Item constraint Initiation (T-0) (hours)

Y/N At rated RCS pressure a potential leakage rate of 21 GPM per RCP following the event is possible. RCS cooldown rate of 75 to 100° F/hr. should Within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> be sustained until stabilized at ~ 300 psig 7 RCS Depressurization and Cooldown. Y 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of T-0 SG pressure. Maintain RCS pressure greater than 250 psig to avoid Cold Leg Accumulator nitrogen injection into the RCS. Cooldown and depressurization should be stabilized within T-4 hours.

This is to ensure switching at the DG building and shutdown board rooms are Alignment of 3 MWe Diesel Generator complete, potential board loading is (DG), 6.9 KV Shutdown Board and reduced and interlocks are cleared to 8 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> emergency feeder breaker and 480 V allow the emergency feeder breakers to Shutdown Board Alignment be used to safely power the 6.9 KV Shutdown Boards from the 6.9KV FLEX DGs.

EA1-3

New ELAP Elapsed Time Task Action time from Event Action Duration Remarks / Applicability Item constraint Initiation (T-0) (hours)

Y/N Energize the 6.9 KV Shutdown Boards with the 6.9KV FLEX DGs. Place the following components in service and restore RCS pressurizer level:

Action initiated to support repowering 9 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />

• Component Cooling System (CCS) Y 1.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> installed pumps to restore RCS Pumps inventory.

• Safety Injection Pumps, as required to recover and maintain RCS pressurizer level.

Place the following equipment in service, if required. Verify 6.9KV FLEX DG loading between component starts.

Action initiated to support repowering 10 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />

• Auxiliary Air Compressors Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> various installed pumps to provide

• Motor Driven Auxiliary Feedwater indefinite coping capability.

Pumps (MDAFWP)

• Spent Fuel Pool (SFP) Cooling Pump (Restore SFP cooling).

The HP FLEX pump discharge can be Stage and align the High Pressure (HP) routed to either Safety Injection Pump FLEX Pumps with suction from discharge headers FLEX connection.

Refueling Water Storage Tank (RWST) 11 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> Y 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> RCS makeup is required to compensate FLEX connections. {Alternate is from for cooldown (shrinkage and boration).

the Boric Acid Tank (BAT) FLEX Hoses will remain isolated and pumps connection for boration}.

out of service until required.

EA1-4

New ELAP Elapsed Time Task Action time from Event Action Duration Remarks / Applicability Item constraint Initiation (T-0) (hours)

Y/N Suction is aligned from the AFWST. The IP FLEX pump discharge can be routed Stage and align the Intermediate to FLEX connections upstream of the Pressure (IP) FLEX pumps at the TDAFWP Level Control Valves (LCV)

Auxiliary Feedwater Supply Tank (primary) or upstream of the MDAFWP 12 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> Y 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> LCVs (alternate).

(AFWST) for backup for SG makeup (backup to the TDAFWP (or) This is a contingency in case of loss of MDAFWPs). the normal SG makeup capabilities.

Hoses will remain isolated and pumps out of service.

Hoses will be routed from an Auxiliary Building el. 714 ERCW FLEX Deploy hoses and spray nozzles as a 13 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> connection to the SFP area or from the contingency for SFP makeup.

demineralized water FLEX connection on el. 714.

This will need to be established within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. This is an assumption and will Initiate fueling operations for diesel 14 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> need to be assessed once all FLEX powered FLEX equipment.

equipment has been purchased and specifications are known.

EA1-5

New ELAP Elapsed Time Task Action time from Event Action Duration Remarks / Applicability Item constraint Initiation (T-0) (hours)

Y/N Makeup to the AFWST will need to be evaluated. The AFWST provides Sources of makeup to the AFWST are approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> for 2 unit identified and FLEX connections are operation. If the Condensate Storage provided to facilitate transfer of quality 15 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Tanks survive the event a total of water. Alignment to the ERCW system approximately 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> of quality and an ultimate heat sink source via the water will be available prior to the LP FLEX pumps remains an option.

requirement to makeup to the AFWST.

This is not a time constraint and MCR and Shutdown Board Rooms are Initiate portable lighting for MCR, provided with battery backup lighting.

16 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Shutdown Board Room and FLEX Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Portable lighting for FLEX equipment equipment locations, as required. staging locations could be required.

Portable lighting will be available for internal and external service, if required.

Monitor TDAFWP Room, Main If required, verify 6.9KV FLEX DG Control Room (MCR), Shutdown loading and restore selected heating, 17 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Board Room, Vital Battery Board ventilation and air conditioning (HVAC)

Room and SFP area ventilation needs. systems to service. (Reference 14)

Evaluate, identify and address long term (within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) needs including:

18 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />

• Mobile water purification unit

• Site diesel and gasoline fuel service.

EA1-6

Attachment 1A Sequence of Events Timeline Flood Event Elapsed Time New ELAP Task Action from Event Action time constraint Duration Remarks / Applicability Item Initiation (T-Y/N (hours) 0)

Note: An ELAP could occur at anytime during flood preparation or a flood event therefore FLEX equipment and strategies must be staged and ready for implementation if required.

Note: The scenario described below assumes an ELAP event occurs post initial flood warning received from TVAs River System Operations and prior to a Stage 1 warning notification. This provides a 27 hour3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> period before flood waters reach grade elevation. This flood preparation time period allows for initial use of the same strategy as a non-flood event for Steps 1-9 for stabilizing the plant and staging FLEX equipment for flood mitigation strategy.

0 Event Starts NA NA Plant @100% power 0 SBO N NA ECA-0.0 (Reference 17)

Initial Load Shed (Station Blackout Sheds 125v DC Vital Loads to ensure 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 1 0 Y .75 hrs.

(SBO) Load Shed) coping.

ELAP entry can be verified by control room staff and it is validated that the Emergency Within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Within 1 Diesel Generators (EDGs) are not available.

2 Declare ELAP N of T-0 hour of T-0 This declaration needs to occur within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from T-0 to provide operators with guidance to perform ELAP actions.

EA1-7

Elapsed Time New ELAP Task Action from Event Action time constraint Duration Remarks / Applicability Item Initiation (T-Y/N (hours) 0)

Sequoyah is developing a post event damage assessment procedure. The damage assessment will evaluate and document the condition of plant systems, structures and components (SSCs) after an ELAP event.

Damage Assessment and Flex The assessment will be consistent with 3 0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Equipment Staging guidelines contained in supplement 5 of reference 16. FLEX equipment staging locations and access routes will be a priority for the damage assessment. This assessment will facilitate debris removal, if required, to support FLEX equipment staging.

Completed with 90 minutes (1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) from T-0. This ensures an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> coping time for Complete Extended Load Shed (Extended the 125v DC Vital Batteries. This ensures 4 0.75 hour8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> Within 1.5 Station Blackout (ESBO) Load Shed) the 125v DC Vital Battery chargers loading hours of T-0 is less than the load limit on the chargers (ensures charging of the batteries).

EA1-8

Elapsed Time New ELAP Task Action from Event Action time constraint Duration Remarks / Applicability Item Initiation (T-Y/N (hours) 0)

At rated RCS pressure a potential leakage rate of 21 GPM per RCP following the event is possible. RCS cooldown rate of 75 to 100° F/hr. should be sustained until Within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> stabilized at ~ 300 psia SG pressure.

5 RCS Depressurization and Cooldown. Y 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of T-0 Maintain RCS pressure greater than 250 psig to avoid Cold Leg Accumulator nitrogen injection into the RCS. Cooldown and depressurization should be stabilized within T-4 hours.

Staged and aligned to take suction from the intake channel and discharge routed to the Stage and align Low Pressure (LP) 6 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Y 4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Essential Raw Cooling Water (ERCW)

FLEX pumps FLEX connections at the Intake Pumping Station (IPS).

This provides charging current to the 125v DC Vital Batteries and ensures 125v DC Align and place in service the 225kva 7 1.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Vital Battery power (control) and through the 480v AC Diesel Generators (DG)

Vital inverters 120v AC Vital Instrument Power (instrument indication).

This is to ensure switching at the DG building and shutdown board rooms are Alignment of 6.9KV FLEX Diesel complete, potential board loading is reduced Generators (DGs), 6.9 KV Shutdown 8 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and interlocks are cleared to allow the Boards, emergency feeder breakers emergency feeder breakers to be used to and 480 V Shutdown Boards.

safely power the 6.9 KV Shutdown Boards from the 6.9KV FLEX DGs.

EA1-9

Elapsed Time New ELAP Task Action from Event Action time constraint Duration Remarks / Applicability Item Initiation (T-Y/N (hours) 0)

Energize the 6.9 KV Shutdown Boards with the 6.9KV FLEX DGs.

Place the following components in service and restore RCS pressurizer level: Action initiated to support repowering 9 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />

• Component Cooling System installed pumps to restore RCS inventory.

(CCS) Pumps.

• Safety Injection Pumps, as required to recover and maintain RCS pressurizer level.

Place the following equipment in service, if required. Verify 6.9KV FLEX DGs loading between component starts. Action initiated to support repowering 11 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />

• Auxiliary Air Compressors Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> various installed pumps to provide indefinite

• Motor Driven Auxiliary coping capability.

Feedwater Pumps (MDAFWP).

• Spent Fuel Pool (SFP) Cooling Pump (Restore SFP cooling).

EA1-10

Elapsed Time New ELAP Task Action from Event Action time constraint Duration Remarks / Applicability Item Initiation (T-Y/N (hours) 0)

Stage and align the second set of Low Pressure (LP) FLEX pumps - staged and aligned to take suction from the road just South of the 5th Diesel Hoses will remain isolated and pumps out of 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Building with discharge routed to the service until required.

Essential Raw Cooling Water (ERCW) FLEX connections at the 5th Diesel Generator Building.

The HP FLEX pump discharge can be routed to either Safety Injection Pump discharge Stage and align the High Pressure headers FLEX connection. RCS makeup is (HP) FLEX pumps with suction from 12 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> Y 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> required to compensate for cooldown the Refueling Water Storage Tank (shrinkage and boration). Hoses will remain (RWST) FLEX connections.

isolated and pumps out of service until required.

Suction hoses are aligned from the AB el.

714 ERCW FLEX connections. The IP FLEX pump discharge hoses can be routed Stage and align the Intermediate to FLEX connection upstream of the 13 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> Pressure (IP) FLEX pumps AB el. Y 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> TDAFWP Level Control Valves (LCVs) 714 for makeup capability to the SGs. (primary) or FLEX connections upstream of the MDAFWP LCVs (alternate).

Hoses will remain isolated and pumps out of service until required.

EA1-11

Elapsed Time New ELAP Task Action from Event Action time constraint Duration Remarks / Applicability Item Initiation (T-Y/N (hours) 0)

Hoses will be routed from an Auxiliary Deploy hoses and spray nozzles as a Building el. 734 ERCW FLEX connection to 14 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> contingency for SFP makeup. the SFP area or from the demineralized water FLEX connection on el. 714.

This will need to be established within 8 Continuous hours. This is an assumption and will need Initiate fueling operations for diesel requirement 15 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Y to be assessed once all FLEX equipment has powered FLEX equipment. once been purchased and specifications are initiated known.

Makeup to the AFWST will need to Sources of makeup to the AFWST are be evaluated. The AFWST provides identified and FLEX connections are approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> for 2 unit provided to facilitate transfer of quality operation. If the Condensate Storage water. Alignment to the ERCW system and 16 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Tanks survive the event a total of Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> an ultimate heat sink source via the LP approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> of quality FLEX pumps remains an option.

water will be available prior to the requirement to makeup to the AFWST.

This is not a time constraint and MCR and Shutdown Board Rooms are provided with Initiate portable lighting for MCR, battery backup lighting. Portable lighting for 17 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Shutdown Board Room and FLEX Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> FLEX equipment staging locations could be equipment locations, as required.

required. Portable lighting will be available for internal and external service, if required.

EA1-12

Elapsed Time New ELAP Task Action from Event Action time constraint Duration Remarks / Applicability Item Initiation (T-Y/N (hours) 0)

Monitor TDAFWP Room, Main If required, verify 3 MWE DG loading and Control Room (MCR), Shutdown 18 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> restore selected heating, ventilation and air Board Room, Vital Battery Board conditioning (HVAC) systems to service.

Room and SFP area ventilation needs.

Evaluate, identify and address long term (within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) needs including:

20 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Y 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />

• Mobile boration unit.

• Site diesel and gasoline fuel service.

EA1-13

Attachment 1B NSSS Significant Reference Analysis Deviation Table WCAP value Item Parameter of interest WCAP page Plant applied value Gap and discussion (WCAP-17601-P January 2013 Revision 1)

There are no deviations.

EA1-14

Attachment 2 Milestone Schedule The following milestone schedule is provided. The dates are planning dates subject to change as design and implementation details are developed. Any changes to the following target dates will be reflected in the subsequent 6 month status reports.

Activity Status Revised Target (Will be Target Activity Completion updated every Completion Date 6 months) Date Submit Overall Integrated Implementation Plan 2/28/2013 6 Month Status Updates Update 1 Aug-2013 Complete Update 2 Feb-2014 Complete Update 3 Aug-2014 Not Started Update 4 Feb-2015 Not Started Update 5 Aug-2015 Not Started Update 6 Feb-2016 Not Started FLEX Strategy Evaluation Jun-2013 Complete Walk-throughs or Demonstrations May-2015 Not Started Perform Staffing Analysis Jun-2014 Not Started Modifications Modifications Evaluation Oct-2013 Complete Unit 1 N-1 Walkdown Oct-2013 Complete Unit 1 Design Engineering Nov-2014 Not Started Unit 1 Implementation Outage May-2015 Not Started Unit 2 N-1 Walkdown Apr-2014 Started Unit 2 Design Engineering Nov-2014 Not Started Unit 2 Implementation Outage Dec-2015 Not Started Storage Storage Design Engineering Sep-2013 Not Started Jul-2014 Storage Implementation Aug-2014 Not Started Jul-2015 On-Site FLEX Equipment Procure Apr-2014 Started Jan-2015 Off-Site FLEX Equipment Develop Strategies with RRC Dec-2013 Complete Install Off-site Delivery Station (if necessary) Apr-2014 Started EA2-1

Procedures PWROG issues NSSS specific guidelines Jun-2013 Started Create Site Specific FSIs Jun-2014 Started Create Maintenance Procedures Jun-2014 Not Started Training Develop Training Plan Jun-2014 Started Training Complete Dec-2015 Not Started Unit 1 FLEX Implementation May-2015 Not Started Unit 2 FLEX Implementation Dec-2015 Not Started Full Site FLEX Implementation Dec-2015 Not Started Submit Completion Report Jan-2016 Not Started EA2-2