ML13206A006

Palo Verde, Units 1, 2 & 3 - Response to Request for Additional Information for Overall Integrated Plan in Response to 03/12/2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design Ba

ML13206A006
Person / Time
Site:	Palo Verde
Issue date:	07/18/2013
From:	Mims D C Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-06733-DCM/DFH, EA-12-049
Download: ML13206A006 (92)

Text

T _ -EA-12-049 t+apsDWIGHT C. MIMSSenior Vice President, NuclearRegulatory

& Oversight Palo VerdeNuclear Generating StationP.O. Box 52034Phoenix, AZ 85072Mail Station 7605Tel 623 393 5403102-06733-DCM/DFH July 18, 2013U.S. Nuclear Regulatory Commission ATTN: Document Control Desk11555 Rockville PikeRockville, MD 20852

References:

1. NRC Order Number EA-12-049, Order Modifying Licenses withRegard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, dated March 12, 20122. APS Letter 102-06670, APS Overall Integrated Plan in Response toMarch 12, 2012 Commission Order Modifying Licenses with Regardto Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049),

dated February 28,20133. NRC to APS Letter (ML13131A259, Palo Verde Nuclear Generating

Station, Units 1, 2, and 3 -Request for Additional Information Regarding Overall Integrated Plan in Response to Commission Order EA-12-049 Modifying License with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events(TAC NOS. MF0829. MF0830. and MF0831),

dated June 20, 2013

Subject:

Palo Verde Nuclear Generating Station (PVNGS)Units 1, 2, and 3, Docket Nos. STN 50-528, 50-529, and 50-530,Response to Request for Additional Information for the PVNGSOverall Integrated Plan in Response to the March 12, 2012Commission Order Modifying Licenses with Regard toRequirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)

On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued an order(Reference

1) to Arizona Public Service Company (APS). Reference 1 wasimmediately effective and directed APS to develop, implement, and maintainguidance and strategies to maintain or restore core cooling, containment, and spentfuel pool cooling capabilities in the event of a beyond-design-basis external event.A member of the STARS (Strategic Teaming and Resource Sharing)

AllianceCallaway-Comanche Peak-Diablo Canyon-Palo Verde-San OnofreSouth Texas-Wolf CreekATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED

ý\6 (

ATTN: Document Control DeskU.S. Nuclear Regulatory Commission, Region IVResponse to Request for Additional Information Page 2Per Section IV, Condition C.1 of Reference 1, on February 28, 2013, APS submitted the PVNGS overall integrated plan (OIP) for mitigating strategies to the NRC(Reference 2).By email dated May 17, 2013, the NRC provided a draft request for additional information (RAI) to APS regarding the integrated plan associated with OrderNumber EA-12-049.

The NRC requested a response to the RAI within 30 days ofreceipt of the email in order to support their review schedule for the integrated plans. On May 30 and June 6, 2013, APS participated in publically available conference calls with the NRC to ensure there was a common understanding of theRAI. On June 20, 2013, in a letter to APS, the NRC submitted the RAI (Reference 3)and in a subsequent conversation with the NRC project manager for PVNGS, the NRCagreed to extend the due date for the response to the RAI to July 18, 2013.The responses developed by APS were reviewed by the Nuclear Energy Institute (NEI) FLEX Task Force Industry Group. Eleven responses were identified as genericindustry topics regarding Order Number EA-12-049.

The nuclear industry will workon these responses generically through NEI and the applicable industry groups. NEIwill coordinate the schedule for resolution with the NRC.The responses to the NRC questions are provided in the enclosure to this letter.Responses containing proprietary or security-related information are provided inseparate attachments to the enclosure.

No commitments are being made to the NRC by this letter.Should you have any questions concerning the content of this letter, please contactPVNGS Operations Support Manager, Regulatory

Affairs, Mark McGhee, at (623) 393-4972.I declare under penalty of perjury that the foregoing is true and correct.Executed on q11_/_/ _- _(Date)Sincerely, Enclosure

-APS RESPONSE TO THE RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, "MITIGATING STRATEGIES FOR BEYOND DESIGNBASIS EXTERNAL EVENTS"ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ATTN: Document Control DeskU.S. Nuclear Regulatory Commission, Region IVResponse to Request for Additional Information Page 3DCM/DFH/hsc cc: E. J. Leeds,A. T. Howell IIIJ. K. RankinJ. P. ReynosoJ. A. Kratchman E. E. BowmanNRC Director Office of Nuclear Reactor Regulation NRC Region IV Regional Administrator NRC NRR Project ManagerNRC Acting Senior Resident Inspector for PVNGSNRR/JLD/PMB, NRCNRR/DPR/PGCB, NRCATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI)REGARDING THE PVNGS OVERALL INTEGRATED PLAN (OIP) FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BEYOND DESIGNBASIS EXTERNAL EVENTS (BDBEE)This Enclosure includes the following attachments:

ATTACHMENT 1 -ACRONYMSATTACHMENT 2 -REFERENCES ATTACHMENT 3 -ESSENTIAL LOAD LIST WITH CRITICAL SAFETY FUNCTION(FROM ENGINEERING STUDY 13-NS-A108, APPENDIX E)ATTACHMENT 4 -SECURITY-RELATED RESPONSES TO RAIATTACHMENT 5 -PROPRIETARY-RELATED RESPONSES TO RAIATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEERequest for Additional Information Regarding Palo Verde Generating StationOverall Integrated Plan in Response to Order EA-12-049 049-RAI-Palo Verde-1Please identify any license amendment requests that are necessary for modifications proposed in the integrated plan.APS Response:

Currently, no required license amendment requests (LAR) have been identified.

LARsmeeting the criterion of the RAI may be identified later in the design development process.APS anticipates submitting this information as a part of a periodic six-month update to theOIP.:1ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-2Attachment 1A of the APS Integrated Plan dated February 28, 2013, lists the operatoractions and associated completion times to mitigate the consequences of an extendedloss of AC [alternating current]

power (ELAP).Discuss how the plant-specific guidance and strategies and the associated administrative controls and training program will be developed and implemented to assure that therequired operator actions are consistent with that assumed in the CENTS [Combustion Engineering Nuclear Transient Simulator]

analysis and can be reasonably achievable within the required completion times.APS Response:

APS is developing a FLEX Support Guideline (FSG): 791S-9ZZ02, PVNGS Extended Loss ofAC Power (Reference 6). The operator actions identified in the FSG are based on the resultsof the CENTS analysis (Reference 5 of the PVNGS Overall Integrated Plan (OIP) February28, 2013, submittal).

APS will develop administrative control programs and training plansconsistent with the guidance in NEI 12-06, Section 2.4, to implement and maintain the FSG.Implementation of these programs will be consistent with existing PVNGS programmatic controls.

Verification of output documents is an integral part of these processes.

APS willprovide to the NRC a description of the beyond-design-bases

program, administrative

controls, and training program as a part of a periodic six-month update to the OIP.2ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-3Pages 18 and 19 of the APS Integrated Plan dated February 28, 2013, state, in part,that:Table Item 9 -Open Control Room Doors: Block open doors to provideventilation to maintain control room temperature.

Reference 7, SectionIX.3 provides a list of rooms reviewed (including the control room) andpredicted temperatures.

Because load shed is to be completed within 2hours, heat loads in the control room are minimal (only essential identified instrumentation is powered).

It is predicted that long term control roomtemperature would approach outside air temperature, per design. ThePVNGS FSG [FLEX Support Guideline]

(Reference

13) will also includesteps to open control room doors.Section 9.2 of Nuclear Energy Institute (NEI) 12-06, Revision 0, "Diverse and FlexibleCoping Strategies (FLEX) Implementation Guide" August 2012 (ADAMS Accession No.ML12242A378),

states, in part, thatVirtually every state in the lower 48 contiguous United States hasexperienced temperatures in excess of 1100F [degrees Fahrenheit].

Many states have experienced temperatures in excess of 1200F.Pages 51 and 52 of the APS Integrated Plan dated February 28, 2013, state thatventilation is not required in Phase 1 and it will not be recovered until Phase 2(approximately 28 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br /> after the ELAP).a. Has a plant-specific, thermal hydraulic calculation been performed to determine what the maximum control room temperature would be based on the NEI 12-06conditions?

If so, please provide a summary of the calculation and its resultsconcluding that control room habitability limits will be maintained in all Phases ofthe ELAP event. If not, please provide the basis and justification for concluding that main control room ventilation will not be required to maintain habitability limits until Phase 2 (28 hour3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br /> mark) of the ELAP event.APS Response:

No analysis has been performed for the control room envelope (CRE) since an engineered solution could not be implemented early in this event. The statement on pages 50 and 52should have indicated that ventilation is "not available" rather than "not required."

Thestatements made on pages 18 and 19 of our submittal are based on the Palo Verde NuclearGenerating Station (PVNGS) Station-Blackout (SBO) analysis and conservative engineering judgment.

Control room temperature during normal operation, with outside temperature at1130F and full operator and staff complement, is maintained less than 750F by design(American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)Weather Station Data, Luke AFB/Phoenix, AZ, USA, WMO#722785, 2009 ASHRAE Handbook-Fundamentals

-Reference 1). The environmental condition inside the control room duringan ELAP is similar to that for an SBO for the first hour of the event. During this time period,the control room SBO analysis assumes a full complement of staff and actuation of most3ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEindicators and alarms in the control room with no functional essential ventilation.

Thepredicted temperature at one hour has been calculated to remain below 1100F. Theprediction of ELAP control room temperature after entry into the FSG was based on threeassumptions:

1. If the CRE is maintained, room temperature will increase due to heat loads fromemergency

lighting, plant instrumentation, and the control room staff.2. The heat load in the room is reduced after the first hour of the event since theamount of energized instrumentation is reduced to one channel, and one train ofemergency lighting will be turned off.3. Notwithstanding items 1 and 2, room temperature will increase at a constant rateas result of fixed heat load and limited heat losses through the walls and floor.Therefore, sometime after the event, control room temperature could possiblyexceed the outside environmental condition.

Any time sensitive action willdepend on the outside air temperature (OSA). The cooler the OSA, the soonerthe control room doors could be opened. If the OSA temperature is hotter thanthe control room, the control room should be kept isolated.

In either case, theCRE will approach and possibly exceed the outside temperature if doors are notopened.Therefore, because of the conditions experienced during an ELAP event, no control roomventilation is available.

The two hour action statement to open the control room doors, asidentified in Attachment A of the OIP, is reasonable based on engineering judgment and NEI12-06, section 3.2.1.7(1).

In conclusion, a course of action will be established in the FSGfor responding to a beyond design-basis event. The FSGs will contain directions foroperating crews to open the CRE prudently for the best possible outcome.b. NEI 12-06 relies on the guidance from NUMARC 87-00, Revision 1, "Guidelines and Technical Basis for NUMARC Initiatives AddreSSing station Blackout at LightWater Reactors,"August 1991 (ADAMS Legacy Accession No. 9209020287),

for a110OF limit for efficient human performance.

NUMARC 87-00 provides thetechnical basis for this habitability standard as MIL-STD-1472C, which concludes that 110OF is tolerable for light work for a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> period while dressed inconventional clothing with a relative humidity of ,30%. In light of this technical basis, please provide justification for the long term habitability of the maincontrol room and/or please indicate what additional relief efforts for the maincontrol room staff will be provided (e.g., short stay time cycles, use of icevests/packs, supplies of bottled water, etc.).APS Response:

Long term habitability will be assured by monitoring control room conditions, heat stresscountermeasures, and rotation of personnel to the extent feasible.

PVNGS procedure 01DP-0IS17, "Heat Stress Prevention Program,"

outlines the issues and the actions to takewhen working in a higher temperature environment and provides various measures tomitigate the effects of working in elevated temperatures for extended periods.4ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEControl room staff will be trained on the expected conditions, the need for self and teammonitoring, and the countermeasures available.

The staffing analysis will addressavailability of replacement personnel, both long term and in the event of medicalemergency.

Additionally, the FSG provides guidance for control room staff to evaluate the control roomtemperature and take actions as necessary.

The initial action would be to open doors to theoutside to obtain the benefit of the external weather conditions in limiting the control roomtemperature.

Additional measures to manage the effects of high temperature on personnel include personnel

rotation, use of cooling blankets, and the availability of drinking water.c. Please clarify the number of plant personnel assumed to be present in the controlroom for this analysis relative to the number of personnel that may be presentduring an ELAP event.APS Response:

As stated in the APS response to 049-RAI-Palo Verde-3a, no specific analysis for ELAP wasperformed.

d. Please discuss the postulated outside air temperature.

APS Response:

As stated in the APS response to 049-RAI-Palo Verde-3a, no specific analysis for ELAP wasperformed.

However, the temperature profile based from the American Society of Heating,Refrigerating, and Air-Conditioning Engineers (ASHRAE)

June weather station data forPhoenix,

Arizona, shows a daily adjusted maximum temperature of 113°F and is consistent with the plant design bases. Although higher temperatures have been observed for shortdurations, it is concluded that higher peak temperatures would only occur for shortdurations.

5ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-4Page 24 of the APS Integrated Plan dated February 28, 2013, states that one train ofatmospheric dump valves (ADV) solenoids will be de-energized during load shed. Pleaseexplain the necessity or prudence of this action and clarify the time required to restorepower to the de-energized train if it becomes necessary.

APS Response:

The Atmospheric Dump Valves (ADV) are described in Section 10.1 of the PVNGS UFSAR.One train of ADV solenoids is deenergized to reduce battery load and extend the availability of the Class 1E Batteries.

Deenergizing one train of ADV solenoids is acceptable becauseonly one ADV is required to remove the expected decay heat and perform a plant cooldownas directed by the FSG. Each ADV is sized to hold the plant at hot standby while dissipating core decay heat or to allow a sufficient flow of steam to maintain a controlled reactorcooldown rate. Palo Verde's strategy is to use one ADV per Steam Generator (SG) toperform a symmetrical natural circulation cooldown of the Reactor Coolant System (RCS).If it should become necessary to restore power to the deenergized ADV train, the powersupply breakers that were opened during the DC load-shed activities can be closed in lessthan twenty minutes.

However, based on NEI 12-06, Section 3.2.1.3, "Initial Conditions"

guidance, this should not be necessary as no additional failures are assumed.6ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-5Page 15 of the APS Integrated Plan dated February 28, 2013, statesInstrumentation on FLEX equipment will be used to confirm adequateperformance of equipment functions.

Please describe the instrumentation that will be used to monitor portable/FLEX electrical power equipment including their associated measurement tolerances/accuracy to ensurethe electrical equipment remains protected (from an electrical power standpoint, e.g.,power fluctuations) and the operator is provided with accurate information to maintaincore cooling, containment, and spent fuel cooling.APS Response:

APS will address instrumentation to monitor portable FLEX electrical power equipment andprovide a response to this RAI during the design and procedure development phase. Safetyfunctions such as core, containment, and spent fuel cooling and inventory control will bemonitored from the unit's control room using seismically qualified, class instrumentation.

Each control room will have the capability of communicating with temporary equipment operators to operate FLEX equipment within the needed range of the safety parameter ofinterest.

APS anticipates providing this information and FLEX portable instrumentation capabilities as a part of a periodic six-month update to the OIP.7ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-6Page 18 of the APS Integrated Plan dated February 28, 2013, states the following:

Table Item 7 -Complete DC [direct current]

Load Shed: DC load shedmust be completed within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> in order to achieve a battery copingtime of 47 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br /> on battery bank B (Reference 16, Section 8.6). ForPhase 1, PVNGS can cope on the installed DC batteries for up to 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />swith no load shedding.

If load shedding, as described in PVNGS Study13-NS-A108 (Reference 7), is completed, the battery coping period isextended to 47 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br />. This load shed strategy will preserve stationbatteries and provide additional time prior to needing to re-energize battery chargers.

a. Provide the DC load profile for the mitigating strategies to maintain core cooling.APS Response:

The referenced battery study is an engineering best estimate based on the published capacity rate of the GNB NCN-33 batteries, which is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to 1.78 VDC. APS plans torevise this analysis as this effort evolves and is updating the battery analysis to includemore specific information as requested in this RAI. The revised analysis will be completed by February 28, 2014.The load profile for the Train B Battery, which has the most limiting load profile, was usedfor the OIP and is summarized below:* 181 amps for the first 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />s* 61.3 amps from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 39 hours4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br />, as identified in Attachment 1A of the OIP* From 39 hours4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br /> to the end of the event, batteries will be charged by 480V FLEXprotable generators during Phase 2 Operations.

b. Provide a detailed discussion on the loads that will be shed from the DC bus, theequipment location (or location where the required action needs to be taken),and the required operator actions needed to be performed and the time tocomplete each action. In your response, explain which functions are lost as aresult of shedding each load and discuss any impact on defense in depth andredundancy.

APS Response:

Included as Attachment 3 are tables of the "Essential Load List with Critical SafetyFunction."

The DC loads section of this list shows the loads that will be shed, the loads thatwill remain energized, and the critical safety function of each load that remains energized.

• Equipment location where action is takeno 100 foot elevation of the Control Building8ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEo 100 foot elevation of the Auxiliary Buildingo 120 foot elevation of the Auxiliary BuildingRequired operator actionso verify breakers closedo open breakers* The time to complete each action0 During a walkdown performed by auxiliary operators in June 2013, actionsassociated with the complete DC load shed were completed within 60 minutesThe tables in Attachment 3 identify loads that remain energized and their safetyfunctions.

No credited safety functions are lost as a result of the DC load shed.To meet the objectives of the FLEX strategies, it is necessary to reduce energized DCloads to one train of equipment.

This approach is consistent with the guidance of NEI12-06 which does not require defense in depth and redundancy.

With the selected loadsof one train energized, necessary instrumentation and equipment needed to monitor theplant and mitigate the event is available.

i. Are there any plant components that will change state if vital alternating current (AC) or DC is lost, de-energized, during this evolution of DC loadshed? When the operators manipulate DC breakers to load shed, willplant components

actuate, de-energize pumps, etc. ? The staff isparticularly interested that a safety hazard is not created, such as de-energizing the DC powered seal oil pump for the main generator, whichwould allow the hydrogen to escape to the atmosphere.

This may causean explosion or fire, and may be compounded by high heat from the mainturbine bearings if not cooled.APS Response:

During the DC load shed evolution, the components and circuits which are deenergized willnot change state in a manner which results in a plant transient or safety hazard.The main generator emergency seal oil pump is powered from nonclass/nonseismic normalDC distribution equipment and any effects on this equipment that may occur during thepostulated ELAP event are not the result of the DC load shed evolution directed in the FSG.If the nonclass DC battery and distribution system remain functional during the event, themain generator will be vented using the Station Blackout (SBO) emergency operations procedure, 40EP-9EO08.

9ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEii. Which breakers will operators open as part of the load shed evolutions?

APS Response:

Attachment 3 provides tables from "Essential Load List with Critical Safety Function,"

whichlist the breakers that plant operators will open. The FSG will provide specific guidance tothe operators to implement load shed activities.

iii. How will the DC breakers be physically identified to assist operators inmanipulating the correct breakers?

APS Response:

Breakers are labeled with an equipment identification tag. APS will rely on the proper use ofhuman performance tools, such as procedure use and self checking, by operators to ensurethe correct breakers are opened.c. The integrated plan states that the batteries can last up to 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with no loadshedding and up to 47 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br /> with load shedding.

The Institute of Electrical andElectronics Engineers (IEEE) Standard 535-1986, "IEEE Standard for Qualification of Class 1E Lead Storage Batteries for Nuclear Power Generating

Stations,

" asendorsed by Regulatory Guide 1.158, "Qualification of Safety-Related LeadStorage Batteries for Nuclear Power Plants,"

February 1989 (ADAMS Accession No. ML003740047),

provides guidance for qualifying nuclear-grade batteries anddescribes a method acceptable to the NRC staff for complying with Commission regulations with regard to qualification of safety-related lead storage batteries fornuclear power plants. Provide documentation that shows that your battery cellsfully comply with the qualification principles in clause 5 and meet therequirements in clause 8.2 of IEEE Standard 535, for the duration you arecrediting the station batteries in your mitigating strategies integrated plan (SeeADAMS Accession No. ML13094A397 for additional information).

APS Response:

This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

10ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-7Page 51 of the APS Integrated Plan dated February 28, 2013, states, in part, thatDC bus voltage is required to be monitored in order to ensure that the DC busvoltage remains above the minimum voltage.Provide the minimum voltage that must be maintained and the basis for the minimumvoltage on the DC bus.APS Response:

Based on engineering

analysis, the minimum estimated voltage on the battery is 106.8 voltsand is delineated in the FSG. The minimum voltage was determined in a best estimatestudy for DC bus voltage requirements.

The study for the DC strategy was a best estimate analysis based on an end voltage of 1.78volts per battery cell. APS will validate the minimum voltage value in the revised analysisdescribed in the response to 049-RAI-Palo Verde-6 to ensure it is based on the most limitingenergized component.

11ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-8NRC Regulatory Guide (RG) 1.128, Revision 2, "Installation Design and Installation ofVented Lead-Acid Storage Batteries for Nuclear Power Plants, " February 2007 (ADAMSAccession No. ML070080013) states, in part, thatConformance with the IEEE Std. 484-2002 requirements (indicated by the verb"shall")

for installation design and installation of vented lead-acid storagebatteries for nuclear power plants provides an adequate basis for complying withthe design, fabrication,

erection, and testing requirements set forth in GDCs 1,17, and 18 of Appendix A to 10 CFR Part 50, as well as Criterion III of Appendix Bto 10 CFR Part 50, subject to the following stipulation...

In Subsection 5.4, "Ventilation,

" revise the second sentence to be consistent with Regulatory Guide 1.189, as follows:"The ventilation system shall limit hydrogen accumulation to one percent ofthe total volume of the battery area. "Please provide a discussion on how hydrogen concentration in the battery rooms will bemaintained below the limits established by national standards and codes (i.e., less than1% according to the National Fire Code and Regulatory Guide 1.128, Revision 2, whichendorses IEEE Standard 484, "IEEE Recommended Practice for Installation Design andInstallation of Vented Lead-Acid Batteries for Stationary Applications,

" with exceptions) when the batteries are being recharged during Phase 2 and 3.APS Response:

PVNGS is not committed to Regulatory Guide 1.128, Regulatory Guide 1.189, or IEEEStandard 484-2002.

APS's strategy will meet the plant's design basis calculation (13-EC-PK-0204),

which calculates 2% hydrogen accumulation in 130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br /> with acomplete loss of ventilation.

During normal and essential plant operations, exhaust fans maintain the hydrogenconcentration of the battery rooms at an acceptable level while the batteries are beingcharged.

If the exhaust fans are not available, battery room doors can be opened.Battery room exhaust fans are listed in Table 1: Installed Loads Credited in Phase 2, page53, of the OIP. According to this submittal, when the FLEX 480 VAC generators are running,the loads identified in Table 1 can be systematically energized.

Guidance for aligning thesystem will be included in the FSG. Per Attachment 1A, "Sequence of Events TimelineModes 1-4," of the OIP, these FLEX generators will be installed and functional by 39 hour4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br />sinto the event. The FSG will ensure the battery room essential exhaust fans are in serviceprior to placing the battery charger into service.

This strategy is consistent with the stationessential HVAC design basis and eliminates any hydrogen concerns.

12ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-9Page 21 of the APS Integrated Plan dated February 28, 2013, states, in part, thatPVNGS will use the standard EPRI [Electric Power Research Institute]

industrypreventative maintenance template for establishing the maintenance and testingactions for FLEX components and that the administrative program will includemaintenance

guidance, testing procedures and frequencies established based ontype of equipment and considerations made within the EPRI templates.

Please provide details of the maintenance and testing plan for electrical equipment thatis credited for events that require mitigating strategies.

The staff is trying to understand how Regulatory Guidance documents, IEEE Standards, manufacturer recommendations, etc. will be utilized to establish the maintenance and testing programs for theportable/FLEX electrical equipment, especially for batteries and diesel generators.

APS Response:

This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

13ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-10Page 59 of the APS Integrated Plan dated February 28, 2013, states, in part, thatThe MV [medium voltage]

FLEX generator will be connected to the Class 1E4.16kV [kilovolt]

switchgear via an installed FLEX junction box mounted outsideon either the west or east wall of the diesel building as shown in Figure 3-39 andFigure 3-41.Describe how the MV FLEX generator and the Class 1E diesel generators are isolated toprevent simultaneously supplying power to the same Class 1E bus in order to conform toNEI 12-06, Section 3.2.2, guideline (13), which specifies that appropriate electrical isolations and interactions should be addressed in procedures and guidance.

APS Response:

The Medium Voltage (MV) FLEX generator will be used only when the Class 1E DieselGenerators are isolated.

The FSG (Reference

6) provides guidance for energizing a Class 1Ebus using portable generators consistent with NEI 12-06, Section 3.2.2, guideline.

The FSGwill provide instructions for aligning the MV FLEX generator(s) to either Train A or Train BClass 4.16 KV switchgear.

Prior to connecting the MV FLEX generators to a switchgear, therespective Class 1E Diesel Generator output breaker will be racked out to prevent potential for cross connection of the two generators.

14ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-11Attachment 1B lists as item 3, a deviation from the WCAP-17601-P, "Reactor CoolantSystem Response to the Extended Loss of AC Power Event for Westinghouse, Combustion Engineering and Babcock & Wilcox NSSS Designs (Proprietary),"

January2013, value for time initiating cool down from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> for the site-specific analysis.

The APS integrated plan shows the operators are performing numerous tasksduring this first hour. Station blackout (SBO) procedures require the operator to startthe station blackout generator (SBOG) within one hour, plus the licensee creditsperforming a load shed on the DC bus within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, and opening doors within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.In addition, the licensee identified two actions with time constraints have beenidentified, observing the condition of the condensate storage tank (CST) and selecting valves that must be closed. In such a critical time operators will be stationed at criticalcomponents such as the steam driven AFW pump. The licensee states that they willperform simulator validations to confirm recognizing ELAP entry conditions.

Provide adescription of tasks to be performed and the personnel available to perform these tasksto allow the staff to evaluate the basis for concluding that these tasks can be reasonably accomplished in the time allotted.

APS Response:

APS does not plan to station Operations personnel at critical components during the initialportions of the Phase 1 FLEX response.

In the current plans, the Auxiliary Feedwater (AFW)pump and ADVs are operated from the control room; therefore, no operators are required tobe stationed locally at the components.

Auxiliary operators will, as part of the FSG actions,be dispatched to verify proper operation locally.APS will perform a staffing study to demonstrate that sufficient action time margin isavailable.

This effort will include comparison of the available analytical timing and marginwith the staffing study results of the NEI 12-01 Phase 2 staffing analysis.

APS expects tosubmit the results of the staffing study by June 2014.15ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-12In its integrated plan dated February 28, 2013, APS has identified that there is a timeconstraint of 34 hours3.935185e-4 days <br />0.00944 hours <br />5.621693e-5 weeks <br />1.2937e-5 months <br /> to install portable 500 kiloWatt (kW) 480 Volt (V) generators inorder to recharge batteries.

APS has not identified a means to move the generators along with the concomitant method for reasonable protection of that means from theidentified hazards applicable to PVNGS as would be required to conform to the guidanceof NEI 12-06, Section 5.3.2, consideration 5 and Section 9.3.2. APS has listedtransportation equipment as equipment to be delivered in the final phase, but hasidentified an open item for the actual sequence and timing of delivery of the equipment.

Please discuss the basis for concluding that the time constraint of 34 hours3.935185e-4 days <br />0.00944 hours <br />5.621693e-5 weeks <br />1.2937e-5 months <br /> canreasonably be met for the installation of the portable generators as specified inNEI 12-06, Section 3.2.1.7, Principle 6, taking into consideration the specifications ofNEI 12-06, Section 5.3.2, Consideration 5 and Section 9.3.2.APS Response:

As of this time, APS has not purchased the 500 kW, 480 V generators nor has the storagelocation for the 500 kW generators been determined.

APS will provide this information in aperiodic six-month update.16ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-13In its integrated plan dated February 28, 2013, APS provided insufficient information tosupport a conclusion that considerations 2 through 4 of NEI 12-06, Section 5.3.3, will betaken into account in the development of the mitigating strategies pursuant to OrderEA-12-049.

These considerations address the potential impacts of large internal floodingsources that are not seismically robust and do not require ac power, the potential reliance on ac power to mitigate ground water, and the potential impacts of non-seismically robust downstream dams. Please discuss the applicability of theseconsiderations at PVNGS.APS Response:

NEI 12-06 section 5.3.3, "Procedural Interfaces,"

considerations 2 through 4 are discussed below:2. Consideration should be given to the impacts from large internal flooding sourcesthat are not seismically robust and do not require ac power (e.g., gravity drainagefrom lake or cooling basins for non-safety-related cooling water systems).

PVNGS does not have any lake or cooling basin for nonsafety related cooling water systemsthat are capable of draining into the safety-related portions of the power block. Thecirculating water basin is at an elevation lower than the unit elevations.

PVNGS does nothave significant internal flooding concerns as a result of nonseismic system failures or fromflooding as a result of gravity drainage of external bodies of water, and there is nopossibility for significant groundwater intrusion into the safety related systems, structures and components (SSC) at the station.

A review of design basis internal station floodingcalculations for the failure of nonseismic cooling water systems confirms that the safetystructures have sufficient capacity to mitigate the consequences of flooding without any ACpower. APS has verified ingress and egress are available at the times needed to locations requiring access for operator action.Flex modifications and portable equipment staging locations supporting the mitigation strategies will consider accessibility, habitability, and two-over-one (2/1) issues as requiredby NEI 12-06, section 5.3.3. APS will revise FSGs, if required, to ensure appropriate directions are provided for possible hazards and limitations.

3. For sites that use ac power to mitigate ground water in critical locations, a strategyto remove this water will be required.

PVNGS does not have an issue requiring continuous removal of groundwater in criticallocations.

4. Additional guidance may be required to address the deployment of FLEX for thoseplants that could be impacted by failure of a not seismically robust downstream dam.17ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEPVNGS has no operational concerns or impacts to the deployment of FLEX related to thefailure of a downstream dam. Additionally, as stated in the OIP, external flooding concernsdo not apply to PVNGS.18ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-14In its integrated plan dated February 28, 2013, APS did not present information on thepotential effects of high ambient temperatures at the locations where portableequipment would operate in the event it is necessary to use the strategies in order toallow the staff to evaluate conformance with NEI 12-06, Section 9.3.2. Please discussthe potential effects of high ambient temperatures on portable equipment in thelocations such equipment would operate.APS Response:

NEI 12-06, Sections 9.3.2 and 9.3.3, state that functionality of FLEX equipment duringmovement in the extreme conditions applicable to the site should be a procurement consideration.

APS will determine the specifications for FLEX equipment, including environmental requirements, during the design development and procedure development phase.Equipment specifications will meet the requirements of NEI 12-06. APS will provide thisinformation in a periodic six-month update.19ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-15In its integrated plan dated February 28, 2013, APS did not present information on theidentification in plant procedures and guidance of portable lighting such as flashlights orheadlamps necessary for ingress and egress to plant areas required for deployment ofthe strategies in order to allow the staff to evaluate conformance with NEI 12-06,Section 3.2.2, paragraph (8). Please discuss arrangements for the use of portablelighting.

APS Response:

The standard gear/equipment for operators with duties outside the control room includesflashlights.

This requirement is currently described in a station procedure and will be addedto the FSG. The DC powered, control room emergency lighting system will be available fora duration of up to 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> as indicated in OIP page 50.Although not credited, Appendix R lighting provides for emergency lighting in select areas ofthe plant where operators or maintenance personnel may need to perform actions duringloss of power conditions.

The Appendix R lights have batteries that last a minimum of 8hours.20ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-16In its integrated plan dated February 28, 2013, APS did not present information onaccess to the Protected Area and internal locked areas in order to allow the staff toevaluate conformance with NEI 12-06, Section 3.2.2, paragraph (9). Please discuss theeffects of ac power loss on area access and the need to gain entry to areas whereremote equipment operation is necessary.

APS Response:

Security-Related Information See Attachment 4 for response.

21ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-17Page 17, Item 2 of the February 28, 2013, APS Integrated Plan submittal states, in part,that "CENTS is approved by the NRC for modeling natural circulation heat removal forsingle phase flow with vapor is present in the reactor vessel head and pressurizer."

Item 16 on page 72 indicates that within 49 hours5.671296e-4 days <br />0.0136 hours <br />8.101852e-5 weeks <br />1.86445e-5 months <br /> of the event initiation, the RCSmakeup pump should be installed for use to maintain sub-cooling natural circulation (NC) and to prevent two-phase NC.Discuss the ELAP coping analysis using CENTS and show that two-phase NC will notbegin prior to initiating the required RCS makeup pump within 49 hours5.671296e-4 days <br />0.0136 hours <br />8.101852e-5 weeks <br />1.86445e-5 months <br />. Discuss thespecific CENTS-predicted RCS conditions that are used to define the initiation of two-phase NC and address adequacy of the use of the specific RCS conditions fordetermination of the time when two-phase NC begins.APS Response:

Westinghouse Proprietary See Attachment 5 for response.

22ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-18Item 13 on page 19 of the APS Integrated Plan dated February 28, 2013, indicates thatthe ADV backup nitrogen supply is sized for 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />, and item 13 on page 71 requiresthat the operator manually operate the ADVs once the nitrogen supply is depleted in 16hours.Please discuss the analysis determining the size of the subject nitrogen supply to showthat the nitrogen source is available and adequate, lasting for 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> for use asmotive force to operate the ADV.Please discuss the electrical power supply that is required for operators to throttle steamflow through the ADVs within 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> and show that the power is available andadequate for the intended use before the operator takes actions to manually operate theADVs. Also, discuss the operator actions that are required to operate ADVs manuallyand show that the required actions can be completed within the required times.APS Response:

The current PVNGS licensing basis for SBO is a 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> coping plant. As part of an earlierlicensing basis change, the SBO analyses were updated from 4 to 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />, including thebackup gas supply to the ADVs, (Reference 11, "Response to NRC Request for Additional Information (RAI) Regarding Revised Station Blackout Evaluation").

Each ADV is a pneumatically modulated control valve supplied by instrument air or by fourdedicated, seismically qualified nitrogen (N2) accumulators.

These accumulators are sizedto allow cooldown of the plant during a natural circulation cooldown from full power toshutdown cooling initiation.

The cooldown is performed using only safety related equipment concurrent with a loss of offsite power and an assumed single active failure.

The PVNGSSBO licensing basis calculation (Reference

3) verifies that the N2 accumulator containsadequate nitrogen mass to perform eleven strokes of ADV function over a 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> SBOcoping period. Based on allowable leakage from the N2 subsystem, the minimum pressurefor the accumulators has been determined to be 615 psig.In addition, high-pressure nitrogen cylinders are installed on a manifold assembly as abackup to the accumulators.

The SBO procedure includes direction to the operators toconnect the supplemental nitrogen system if needed. The procedure provides the stepsnecessary for the operators to connect the supplemental nitrogen system, as needed, toback up the nitrogen accumulators for extended operation of the ADVs (References 4 and5).Please discuss the electrical power supply that is required for operators to throttle steamflow through the ADVs within 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> and show that the power is available andadequate for the intended use before the operator takes actions to manually operate theADVs.23ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEAPS Response:

PVNGS load shedding study 13-NS-A108 demonstrates sufficient power is available for twoADVs to remain available for greater than 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> after load shed along with theassociated

control, indication and power to four DC solenoid valves for the nitrogen supplyto the ADVs.Also, discuss the operator actions that are required to operate ADVs manually and showthat the required actions can be completed within the required times.APS Response:

Manual operation of the ADVs is accomplished using Appendix 18, "Local ADV Operation,"

ofprocedure 40EP-9EO10, Standard Appendices.

This appendix has four attachments, one foreach ADV, which describe the actions required to take local/manual control of the ADVs. Totake local control of the ADV the operator must perform the following actions:* Verify instrument air is isolated to the ADV (time -about 2 minutes)* Isolate the ADV nitrogen accumulator supply (time -about 1 minute)* Open the ADV actuator equalizing valve (time -about 1 minute)* Align the ADV manual override actuator shaft and install the locking clevis (time -about 5 minutes)* Operate the ADV as directed by the control roomThe time required to align the ADV for local/manual operation is less than 15 minutes oncethe Auxiliary Operator (AO) is at the ADV location.

When the ADV is aligned forlocal/manual operation, the AO may open or close the ADV as directed.

The ADV requires19 complete turns of the handwheel for each 10% change in valve position.

24ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-19Please clarify the accuracy with which steam generator pressure can be controlled bymanual operation of ADVs after the nitrogen supply is depleted.

For example, shouldsteam generator pressure drop too low, turbine-driven auxiliary feedwater flow could beinterrupted or accumulators could rapidly empty. Please provide adequate basis toconfirm that manual operation of the ADVs under ELAP conditions would be conducive tomaintaining a reasonably constant steam generator pressure.

Please further describehow manual ADV control will be accomplished (e.g., communication between the controlroom and a local operator stationed at the ADV), and, as applicable, whetherenvironmental factors such as the potential for ambient noise and heat due to exitingsteam have been considered.

APS Response:

The coping strategy for a SBO event requires 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> (Reference

4) of ADV operation usingthe nitrogen accumulators.

Local/manual operation of the ADVs would not be required until16 hours after the initiation of the ELAP event. At that time, the RCS cooldown will becompleted, and the rate of change in decay heat will be small and decreasing.

As a result,the expectation is that the ADVs will need to be closed to ensure adequate steam pressureto operate the Steam Driven Auxiliary Feedwater Pump. Additionally, the FSG contains acaution to make changes slowly during natural circulation because it takes about 10 minutesto observe the effects of any adjustment in heat removal.The AO will manually control the ADVs by taking local/manual control of the ADV asdescribed in the response to 049-RAI-Palo Verde-18.

The AOs will establish communication with the control room by using radios, satellite phones, or sound powered phones. A soundpowered phone jack is located at each ADV operating platform and in the control room.PVNGS has previous experience in local operation of the ADVs. There is some impact due tonoise; however, in the past, PVNGS operators were able to communicate using radios whilemanually operating the ADVs. The AOs operating the ADVs could use hearing protection ora headset to minimize the noise impact. The ADVs are operated from inside the main steamsupport structure (MSSS) and the steam exiting the ADVs exhausts outside the MSSS at theroof area.25ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-20Item 18 on page 19 of the integrated plan dated February 28, 2013, indicates that whenthe CST depletes, the turbine driven auxiliary feed water pump (TDAFWP) suction pathis required to realign to the Reactor Makeup Water Tank (RMWT) within 45 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br />. Item21 of Attachment 1A requires the operator to supply water from the water reclamation facility (WRF) to the CST within 116 hours0.00134 days <br />0.0322 hours <br />1.917989e-4 weeks <br />4.4138e-5 months <br /> when the available water in the CST andRMWT is depleted.

a. Please discuss the analysis to show that the required CST -RMWT switchover time is no greater than 45 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br />, and realignment time of the WRF to the CST iswithin 116 hours0.00134 days <br />0.0322 hours <br />1.917989e-4 weeks <br />4.4138e-5 months <br />.APS Response:

Switching AFW suction from the CST to the RMWT requires opening one manual valve,AFA-V058, followed by closing one manual valve, AFA-V006.

These instructions areincluded in the FSG (Reference 6, Step 3.21). Valves AFA-V058 and AFA-VO06 are locatedin the AFW turbine-driven pump room. The inventory in the CST is sufficient to last 45hours (Reference 7, Attachment 1A) before realignment to the RMWT becomes necessary.

Reference 27 analyzes the planned cooldown of the plant, determining the requiredcondensate volume necessary to remove the heat within the water and metal mass of theRCS in addition to decay heat. The results of this analysis along with the water volume ofthe CST were used to determine the required switchover time in Reference 28 and arepresented in Reference 7, Attachment 1A. Reference 6 instructs the operator to take thisaction based on a specified CST level indication, which will be available during this event,and not event time. Assuming a 30 minute operator action time to manipulate the valves,the realignment can be completed well ahead of the required time.The inventory in the CST and RMWT is sufficient to last 116 hours0.00134 days <br />0.0322 hours <br />1.917989e-4 weeks <br />4.4138e-5 months <br /> (Reference 7, Attachment 1A) after shutdown.

Similar to the CST/RMWT switchover required time, the analysis inReference 22 was used in Reference 28 to determine the time when makeup from the WaterReclamation Facility (WRF) would be required.

That time is presented in Reference 7,Attachment 1A. Makeup from the WRF to the CST will be established by running temporary piping from one of the WRF reservoirs to the CST at each unit. The start time forinstallation of the temporary piping will be based on the estimated time for construction with sufficient margin to the 116 hours0.00134 days <br />0.0322 hours <br />1.917989e-4 weeks <br />4.4138e-5 months <br />.b. The licensee stated in Table Item 18 on page 19, "Condensate Storage Tank(CST) Empties-Switchover to Reactor Makeup Water Tank (RMWT) (Refueling Water Tank (RWT) (for high Seismic Event)):

When the CST depletes, theTDAFW pump suction path is realigned to RMWT. " Please explain how corecooling will be maintained during this transition period.APS Response:

As the CST inventory

depletes, the RMWT can be aligned to the AFW suction.

Reference 6,Step 3.21, instructs the operator to open AFA-V058, which opens the suction path to the26ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEETurbine Driven Auxiliary Feedwater (TDAFW) pump from the RMWT. After AFA-V058 isopen, AFA-V006 is closed, isolating the suction path to the CST. There is always a suctionsource available to the TDAFW pump, which will allow the pump to continue operating during the suction swap to maintain core cooling.The Refueling Water Tank (RWT) is considered a defense-in-depth water source. If theRMWT is not available, the RWT may be used as a makeup source to the CST, not as adirect suction source to the TDAFW pump. The transfer process will use flexible hoses and aportable pump with sufficient flow capacity to match or exceed TDAFW pump flow to refillthe CST. The TDAFW pump will have an uninterrupted suction supply from the CST, whichwill allow the pump to continue to operate to maintain core cooling.In either case, if AFW delivery is temporarily lost during the realignment of another source,decay heat levels are lower at this point in the event compared to shortly after shutdown.

Also, the applicable FSG instructs operators to maintain the Steam Generators (SG) 85%full (wide-range level) (Reference 6). As a result, operators would have time to reestablish makeup to the SGs before inventory in the SGs has depleted.

c. Figure 3-3 on page 81 shows valve "V058" from the RMWT to the AFW suctionpiping. Please describe the location of this valve and the probable accessibility following an ELAP event, and describe how the RMWT can provide water to theAFW pump.APS Response:

The RMWT is designed with a dedicated piping connection from the RMWT to the TDAFWpump suction.

This connection is normally isolated by valve AFA-V058 located in theTDAFW pump room. This room is on the 80 ft. elevation of the MSSS. There are two waysto access this location.

The first is a stairwell near the Turbine Building.

At the bottom ofthe stairwell is a door into the TDAFW pump room.The second access is from the 100 ft. level (ground level) of the MSSS. On this level, thereis a hatch and ladder leading to the moter driven auxiliary feedwater (MDAFW) pump room.There is a doorway from the MDAFW pump room to the TDAFW pump room. This accesspath does not require the operator to enter any nonseismically qualified structures to reachthe valve.These areas are also part of the secondary-side walkdown in the FSG (Reference 6,Appendix C). Any accessibility issues would be identified early in the event, before AFA-V058 would need to be operated.

d. The description of Table Item 18 on page 19 indicates that for high seismicevents, the operators will switch over to the RWT, but this is not reflected inTable Item 18 on page 72 or Figure 3-3 on page 81. Please describe how theRWT can provide AFW to the TDAFW pump.27ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEAPS Response:

As described above, the RWT cannot directly provide suction to the TDAFW pump. Thisstrategy uses portable pump(s) to refill the CST with RWT inventory, as discussed inReference 6, Appendix J. The TDAFW pump would then continue to take suction from theCST. This strategy is only included for defense in depth, as the CST and RMWT are bothseismically robust sources of sufficient volume.28ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-21Page 23 of the APS integrated plan dated February 28, 2013, indicates that theemergency operating procedures (EOPs) direct the operators to take action to confirmthe closure of the main steam isolation valves (MSIVs).

Simultaneous closure of MSIVsfor all three units will result in loss of auxiliary steam to the air ejectors and loss ofgland seal steam. Provide a description of the affects of losing auxiliary steam to allthree units, especially on the turbine if vacuum is lost rapidly.APS Response:

As stated in the OIP, the SBO EOP directs operators to ensure a Main Steam Isolation Signal(MSIS) has actuated to close all MSIVs. After the MSIVs are closed, the Main Steam systemwill eventually depressurize, resulting in depressurization of the Auxiliary Steam system.Auxiliary Steam system loads which lose pressure include the Gland Seal system andvarious nonclass radioactive waste processing systems.

PVNGS does not use steam jet airejectors to maintain main condenser vacuum. Instead, PVNGS uses air removal vacuumpumps that will be deenergized at the onset of the ELAP event. The impact on the mainturbine from loss of vacuum is a shorter stop time than if vacuum had been maintained.

29ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-22Page 24 of the APS integrated plan dated February 28, 2013, statesWithout ventilation, the TDAFWP room temperature will exceed 130OF within four(4) hours. PVNGS has determined that opening the access doors to the roomwithin 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> will limit the temperature to a maximum of 130°F, therebymaintaining pump availability.

a. This description implies that there is no margin to the maximum temperature.

Please discuss if conservatisms exist in the analysis and/or the identification ofadditional operational margin with respect to the TDAFWP room temperature andthe continued operation of the TDAFWP.APS Response:

The statement referenced above contains an error. It should read, "Without ventilation, theTDAFWP room temperature will not exceed 130OF within four (4) hours." A mitigating strategy has been developed that credits opening doors at the 80 ft and 100 ft elevation attwo hours when the room temperature is near 1200F. This mitigating action will limit themaximum temperature to less than 130OF for the remainder of the event.The analysis is performed with an initial TDAFWP room temperature of 950F. This value wasselected to envelop all measured TDAFWP room temperature data collected during themonths of August and September 2012 in all three units without pump testing in progress.

An outside diurnal temperature profile was applied based on American Society of Heating,Refrigerating and Air Conditioning Engineers (ASHRAE) weather station data for June inPhoenix, AZ with a daily maximum temperature of 1131F. Since the TDAFWP room is belowplant grade, the room temperature response is relatively insensitive to the outsidetemperature while the access door is closed. With the door open, exchange of air betweenthe TDAFWP room, stairwell, and turbine building breezeway does occur, and the timing ofthe peak room temperatures coincides with the outside daily maximum.Several conservative assumptions are applied in the analysis of the TDAFWP roomtemperature response:

• Heat conduction into the ground from the north wall and the floor are ignored." A minimal heat transfer coefficient of 1.0 Btu/hr-ft 2.OF is used for the heat transfer tothe gap between the MSSS and Containment Building on the west side of the room.* The temperature of the outside wall on the east side of the room adjacent to the pipetunnel is set to a constant value of 128.50F.* The initial temperature of the MSSS rooms located above the TDAFWP room is set tothe building design temperature of 1200F.* The heat addition rate into the MSSS rooms located above the TDAFWP room fromthe feedwater piping does not credit decreasing feedwater temperature in theisolated lines.30ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE" Steam leakage into the TDAFWP room from the gland seals and casing drain isassumed to remain constant throughout the event and does not decrease as the SGpressure is lowered.* The surface temperatures of the condensate drain lines and turbine steam exhaustpiping are increased to the maximum expected values immediately following AFWactuation and are held constant for the duration of the event.b. Please clarify whether the initial temperature condition assumed the worst-case outside temperature with the plant operating at full power. Provide the list ofelectrical components that are located in the TDAFWP room and are necessary toensure successful operation of the TDAFWP. Also, please provide the qualification level for temperature and pressure for these electrical components for theduration that the TDAFWP is assumed to perform its mitigating strategies function.

APS Response:

Table 1 below provides a list of equipment located in the TDAFWP compartment (roomC-09). NUMARC 87-00, Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors, section 2.7.1 (2) (Reference

9) was used todetermine the functionality of these components.

Based on the analysis described in theresponse to 049-RAI-Palo Verde-22a above, the TDAFWP compartment meets condition 2 ofNUMARC 87-00 and equipment within the compartment remains functional and continues toperform its intended function during an ELAP.049-Palo Verde RAI-22 -Table 1List of Equipment in Auxiliary Feedwater Turbine Driven Pump RoomItem Equipment Short Component Description Manufacturer DCID Description 1 JAFAE01**INSTRU AFW Control AUX.FDWTR.CONTROL Terry TurbinePanel PANEL2 JAFAE01*CON1*RELAYX Motor Starter RELAY MTR STARTER FOR Allen BradleyRelay VALVE J-AFA-HV-54 3 JAFAE01*CRI*RELAYX Auto Reset RELAY AUTO RESET FOR AmeraceRelay VALVE 1J-AFA-HV-54 4 JAFAE01*CR2*RELAYX Alarm Relay RELAY CONTROL POWER AmeraceLOSS ALARM FOR VALVEJ-AFA-HV-54 5 JAFAE01*CR4*RELAYX Ramp Starter RELAY RAMP START AUX PotterRelay FEEDWATER TURB Brumfield 6 JAFAE01*CR5*RELAYX Overspeed RELAY TURBINE PotterTrip Relay OVERSPEED TRIP FOR Brumfield VALVE J-AFA-HV-54 31ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEItem Equipment Short Component Description Manufacturer DCID Description 7 JAFAE01*R17*INSTRU Dropping DROPPING RESISTOR VishayResistor R17, (EG-M POWER Intertech SUPPLY-48 VDC)[ AFWCTRL PANEL]8 JAFAFT0040A**IXMITR Flow AUX FEEDWATER FLOW Rosemount Transmitter TO SG 19 JAFAPT0018**IXMITR Pressure AUX FEEDWATER PUMP Rosemount Transmitter AFA-P01 DISCHPRESSURE INDICATION 10 JAFBFT0041A**IXMITR Flow AUX FEEDWATER FLOW Rosemount Transmitter TO SG 111 JSGAPT0313**IXMITR Pressure ADV-179 AND ADV-184 Rosemount Transmitter TRANSMITTER PRESSUREFOR ATM DUMP VALVECONTROL12 JAFAHV0032**MOTORX AFW Pump AUX FEEDPUMP AFA-P01 Peerless Elec.Motor FLOW CONTROL VALVEOperator TO SG 113 JAFAHV0032**VALVOP AFW Motor AUX FEEDPUMP AFA-P01 Limitorque Operator FLOW CONTROL VALVETO SG 114 JAFAHV0054**MOTORX Turbine Trip AUX FEEDPUMP AFA-P01 Peerless Elec.Motor TRIP & THROTTLE VALVEOperator15 JAFAHV0054**VALVOP Turbine Trip AUX FEEDPUMP AFA-P01 Limitorque Operator TRIP & THROTTLE VALVE16 JAFAUV0037**MOTORX AFP Isolation AUX FEEDPUMP AFA-P01 Peerless Elec.Valve Motor FEED ISOLATION VALVEOperator TO SG 217 JAFAUV0037**VALVOP Isolation AUX FEEDPUMP AFA-P01 Limitorque Valve Motor FEED ISOLATION VALVEOperator TO SG 218 JAFCHV0033**MOTORX AFW Motor AUX FEEDPUMP AFA-P01 Peerless Elec.Operator FLOW CONTROL VALVETO SG 219 JAFCHV0033**VALVOP AFW Motor AUX FEEDPUMP AFA-P01 Limitorque Operator FLOW CONTROL VALVETO SG 220 JAFCUV0036**MOTORX AFP Isolation AUX FEEDPUMP AFA-P01 Peerless Elec.Valve Motor FEED ISOLATION VALVEOperator TO SG 121 JAFCUV0036**VALVOP Isolation AUX FEEDPUMP AFA-P01 Limitorque Valve Motor FEED ISOLATION VALVEOperator TO SG 132ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEItem Equipment Short Component Description Manufacturer DCID Description 22 JSGAHY0184C**INTCPM Converter I/P ADV-184 I/P CONVERTER Masoneilan CONVERTER I/P SG 1LINE 1 ATM DUMP VALVE23 JSGBHY0178C**INTCPM Converter I/P ADV-178 I/P CONVERTER Masoneilan CONVERTER I/P SG 1LINE 2 ATM DUMP VALVE24 JSGAZT0184**IXMITR Position ADV-184 POSITION Schaevitz Transmitter TRANSMITTER 25 JSGBZT0178**IXMITR Position ADV-178 POSITION Schaevitz Transmitter TRANSMITTER 26 JAFAHS0052B**CKTBRK Hand Switch AF TURB O.S. TEST J.B.T.SWITCH HAND AFTURBINE OVERSPEED TEST,LOCAL PANEL27 JAFAHS0052C**CKTBRK Hand Switch AF TURB SPEED Micro SwitchCONTROLXFER SWITCH HAND AF TURBSPEED CONTROLTRANSFER,LOCAL PANEL28 JAFAHS0054C**CKTBRK Hand Switch AF TURB TRIP LP Allen BradleySWITCH HAND AFTURBINE TRIP LOCALPANEL29 JAFAHS0054E**CKTBRK Hand Switch LOCAL HS FOR "A" AFW Micro SwitchPUMPTURBTRIP/THROTTLE VALVESWITCH HAND AFTURBINE TRIP VALVEJOG,LOCAL PANEL30 JAFASI0052C**INDREC Speed AUX FDWTR TURBINE Beede Elect.Indicator SPEED INDICATOR-LOCAL PNLINDICATOR SPEEDAUXILIARY FEEDWATER TURBINE,LOCAL PANEL31 JAFASK0052C**ICNTRL Speed AUX FDWTR PUMP Beckman Instr.Controller ATURBINE SPD CNTRL-LCL PNL CONTROLLER SPEED AUX FEEDWTRPUMP A TURB,LOCAL PANEL32 JAFAST0052**IXMITR Speed AUX FEEDWTR TURBINE Woodward GovTransmitter SPEED TRANSMITTER AUXILIARY FEEDWTRTURBINE33ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEItem Equipment Short Component Description Manufacturer DCID Description 33 JAFAHY0054**VALVOP Solenoid OPERATOR SOLENOID Trombetta Operator AUX FEEDWTR TURBINETRIP VALVE34 MAFAK01**ICNTRL Governor GOVERNOR AUXILIARY Woodward GovControl Unit FEEDWATER PUMPTURBINE ELECTRONIC GOVERNOR AUXILIARY FEEDWATER PUMPTURBINE ELECTRONIC CONTROL UNIT35 MAFAK01**MECFUN Governor GOVERNOR AUXILIARY Woodward GovFEEDWATER PUMPTURBINE36 JSGBPT0301**IXMITR Pressure ADV-178 ACCUMULATOR Rosemount Transmitter NITROGEN PRESSTRANSMITTER 37 JSGAPT0315**IXMITR Pressure ADV-184 ACCUMULATOR Rosemount Transmitter NITROGEN PRESSTRANSMITTER 34ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-23a. Please list the safety and non-safety-related systems or equipment that are creditedin the ELAP analysis.

For the non-safety-related systems or equipment, pleasediscuss the safety functions that are intended to maintain and justify how the non-safety-related systems or equipment are available and reliable for their intended use.APS Response:

Equipment,

systems, and structures credited for the OIP strategies are safety related exceptfor the upper portion of the CST and the RMWT and its associated piping. Both the RMWTand the upper portions of the CST are designed to 10 CFR 50 Appendix B augmented quality(i.e., seismic 2 over 1) and to withstand an operating basis earthquake (OBE). As described on page 26, Notes: Item 1, of the OIP, the seismic fragility evaluations were performed using the guidance contained in EPRI NP-6041-SL Revision 1, "A Methodology forAssessment of Nuclear Plant Seismic Margin,"

August 1991 (Reference 10). The CST upperportions and the RMWT and associated systems were found to be robust with a calculated acceptable high-confidence-of-low-probability-of-failure (HCLPF) capacity compared with thestation Safe Shutdown Eartquake (SSE) seismic level. As a contingency for these watersources, the FSG also provide guidance for the transfer of water from the RWT, which is aseismic category 1, quality-related structure.

Equipment needed to transfer water from theRWT to the CST is currently on site and would be deployed as a mitigating strategy.

b. Please justify that the instrumentation listed on pages 25 -26 and pages 33 -34 ofthe APS integrated plan dated February 28, 2013, and the associated setpoints credited in the ELAP analysis for automatic actuations and indications required forthe operator to take appropriate actions are reliable and accurate in the containment harsh conditions with high moisture levels, temperature, and pressure during theELAP event.APS Response:

As described in the OIP, pages 25 and 26, a minimum set of instrumentation has beenselected to provide control room operators with key safety-function information.

Instruments identified are safety related, seismically qualified, meet the environmental qualification requirements of 10 CFR 50.49, and are verified qualified consistent with thecriteria in NEI 12-06, Section 3.2.1.12.

The PVNGS ELAP analysis does not credit automatic actuation beyond the SBO scenarios, and such actions would occur within the first hour ofthe event. The SBO response strategies were reviewed and approved by the NRC inReference

5. Operator actions directed by the FSG are manual actions after the first hour.Instrumentation and components credited are qualified to 10 CFR 50.49 for loss of coolantaccident (LOCA) and steam line break; therefore, they will remain accurate and reliable forthe duration of the beyond-design-bases event. Additionally, the maximum temperature expected within containment during an ELAP remains below the threshold of the equipment qualification harsh limit of 2300F.35ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-24The last paragraph on page 32 and item 2 on page 74 of the APS integrated plan datedFebruary 28, 2013, indicate that PVNGS RCP seals are assumed to have a maximumleakage of 17 gallons per minute (gpm) per pump at normal operating pressure.

Please discuss an analysis or RCP seal leakage testing data to show adequacy of the RCPseal leakage rate of 17 gpm per pump assumed in the ELAP analysis.

The RCP sealleakage testing data used to support the assumed leakage rate should be applicable tothe PVNGS RCP seals (with respect to the seal material, design and seal coolingsystems) and ELAP conditions (in terms of the temperature and pressure, and sealfailure mechanisms discussed in Section 6.4 of WCAP-17601

-P) for an extended periodconsistent with the ELAP coping time. Also, please address applicability of theinformation In Section 4.4.2 of WCAP-17601, Rev. 0, which states"It has been shown that the probability of seal failure greatly increases whenthere is less than 50OF of subcooling in the Cold Legs."APS Response:

Westinghouse

-Proprietary See Attachment 5 for response.

36ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-25Item 36 on page 15 of the APS integrated plan dated February 28, 2013, states, in part,thatOperator actions are credited for cooling and depressurizing the RCS.... RCP sealleakage rates are dependent on RCS pressure and will decrease with deceasing pressure."

Please discuss how CENTS calculates the pressure-dependent RCP seal leakage rates. IfCENTS uses the equivalent size of the break area based on the initial leakage rate of 17gpm per pump to calculate the pressure-dependent RCP seal leakage rates during theELAP, please discuss whether the size of the break area is changed or not in the analysisfor the ELAP event. If the size is changed, discuss the changed sizes of the break areaand address the adequacy of the sizes. If the break size remains unchanged, addressthe adequacy of the unchanged break size throughout the ELAP event in conditions withvarious pressure, temperature (considering that the seal material may fail due to anincreased stress induced by cooldown) and flow conditions that may involve two-phase flow which is different from the single phase flow modeled for the RCP seal tests that areused to determine the initial seal leakage rate of 17 gpm.APS Response:

Westinghouse

-Proprietary The proprietary portion of this response is provided in Attachment 5.This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

37ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-26The third paragraph on page 35 of the APS integrated plan dated February 28, 2013,states, in part, thatPVNGS control rod shutdown margin and borated water inventory in the RCS andSITs [safety injection tanks] are sufficient to prevent re-criticality of the core. "Please discuss the boron mixing model used for the re-criticality analysis in support ofthe plant FLEX mitigation strategies, and address the adequacy of the boron mixingmodel for the intended purpose with support of an analysis and/or boron mixing testdata applicable to the ELAP conditions.

APS Response:

Westinghouse

-Proprietary The proprietary portion of this response is provided in Attachment 5.This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

38ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-27Tables A and B of the February 28, 2013, submittal list the phases 2 and 3 portableequipment required for the ELAP mitigation.

Table A lists four self priming pumps andfour high pressure RCS makeup pumps that are required during the phase 2 of ELAP.The required capacities of the pumps are 370 gpm (at 500 psi) and 30 gpm (at 1525psi) for the priming pumps and high RCS makeup pumps, respectively.

Table B listshigh pressure RCS makeup pumps and pumps to makeup to the CST from reservoirs that are required during the phase 3 of ELAP. The required capacities of the respective pumps are 30 gpm (at 1525 psi) and 1200 gpm (at 130 psi).Specify the required times for the operator to realign each of the above discussed pumps and confirm that the required times are consistent with the results of the ELAPanalysis.

Discuss how the operator actions are modeled in the ELAP to determine the requiredflow rates of the portable pumps, and justify that the capacities of each of the abovediscussed pumps are adequate to maintain core cooling during phases 2 and 3 of ELAP.APS Response:

Westinghouse

-Proprietary See Attachment 5 for response.

39ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-28Attachment 1A lists the sequence of events timeline for Mode 1-4. On page 70, item 11indicates that the analysis assumes cooldown initiation time of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and that the RCScooldown to 3501F is expected to complete within 4.11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> of initiation of the event.List the operator actions credited in the analysis to complete the cooldown from 1 hourto in 4.11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />, and discuss how the operator actions are modeled in the cooldownanalysis for the 4.11 -hour period using CENTS.APS Response:

APS performed the CENTS studies first and then determined the operator actions and timeframes necessary to comply with the study. The CENTS computer code is an interactive, faster-than-real-time computer code for the simulation of Nuclear Steam Supply Systemsand related systems.

The CENTS code allows the user to run the code using preselected dynamic conditions or by inputting parameters into the code manually to make changes,take manual actions, or initiate malfunctions.

This provides a means to evaluate transient conditions.

Although additional actions will be taken by the operators to perform the plant cooldown, the actions which are credited in the analysis to complete the cooldown are described below. All of the credited actions are performed from the control room.* Initiate a cooldown by adjusting the B Train ADV position on each SG to increasesteam flow and establish a cooldown rate of approximately 70°F per hour* Feed the SGs with the TDAFWP to achieve and maintain SG water levels at 85%narrow range (NR). This approach increases the available volume of secondary water" Stop the cooldown and stabilize the plant by adjusting the B Train ADV position oneach SG to decrease steam flow. The plant is stabilized at an analytical limit of:o 350WF (primary) o 135 psia (secondary) 40ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-29Item 2 on page 68 of the February 28, 2013, submittal indicates that at 0.017 hours1.967593e-4 days <br />0.00472 hours <br />2.810847e-5 weeks <br />6.4685e-6 months <br /> (60seconds),

the TDAFWP begins.The above information appears inconsistent with that listed in Table 5.1-1 ofDAR-TDA12-2 (Reference 5 to the integrated plan), "Sequence of Events" for the casewith the RCP leakage rate of 17 gpm/pump.

Table 5.1-1 indicates that at 0.203 hours0.00235 days <br />0.0564 hours <br />3.356481e-4 weeks <br />7.72415e-5 months <br />,the auxiliary feedwater (AFW) actuation signal actuates for steam generator (SG) 1.With a 60-second delay, the AFW flow to both SGs begins from the TDAFW pump at 0.22hours. Clarify and correct the inconsistency.

APS Response:

The time for the TDAFWP to supply flow to the SGs presented in Reference 27 is correct,and the time in the February 28, 2013, submittal (Reference 7), Page 68, Item 2 should becorrected to reflect 0.220 hours0.00255 days <br />0.0611 hours <br />3.637566e-4 weeks <br />8.371e-5 months <br />.The TDAFWP start time in the sequence of ELAP events was based on a 60 second (0.017hour) delay in start of TDAFWP after the Auxiliary Feedwater Actuation Signal (AFAS) isinitiated as a result of low level in the SGs. This time delay is conservative relative to the_<46 second start time required in the Updated Final Safety Analysis Report (UFSAR)(Reference 26), Table 7.3-1B, Engineered Safety Features Response Times.An ELAP analysis was performed in Reference

27. During an ELAP event, the AFAS wouldnot occur until SG level drops to the SG low level setpoint.

In Reference 27, AFAS isconservatively initiated at a lower level than the PVNGS setpoint to accommodate uncertainty.

In Case 1, which is representative of all 4 ELAP cases documented inReference 27, the AFAS for SG 1 and SG 2 is generated and AFW flow to both SGs occurs at0.220 hours0.00255 days <br />0.0611 hours <br />3.637566e-4 weeks <br />8.371e-5 months <br /> with acceptable results.41ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-30Section 3.2 of WCAP-17601-P discusses the PWR Owners Group's recommendations thatcover following subjects for consideration in developing FLEX mitigation strategies:

(1) RCP seal leakage rates; (2) adequate shutdown margin; (3) time initiating cooldownand depressurization; (4) prevention of the RCS overfill; (5) blind feeding an SG with aportable pump; (6) SIT performance; and (7) asymmetric natural circulation cooldown(NCC).Discuss the licensee's position on each of the recommendations discussed above fordeveloping the FLEX mitigation strategies.

List the recommendations that are applicable to the plant, provide rationale for the applicability, address how the applicable recommendations are considered in the ELAP coping analysis using CENTS, and discussthe plan to implement the recommendations.

Also, provide rationale for each of therecommendations that are determined to be not applicable to the plant.APS Response:

Westinghouse

-Proprietary See Attachment 5 for response.

42ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-31Item 1 on page 74 of the February 28, 2013, submittal indicates that the licensee uses aplant specific best estimate (BE) decay heat curve in the thermal hydraulic analysis forthe ELAP event. The licensee states that the use of the plant-specific BE decay heatcurve is a deviation from WCAP-1 7601, but claims that the deviation is justified byCN-REA-12-36 (Reference 7 to the integrated plan).Provide the justification for the NRC staff to review. Alternatively, if CN-REA-12-36 hasdocumented the appropriate justification, the licensee could provide the relevant pagesfor the NRC staff to review and approve.APS Response:

Westinghouse

-Proprietary See Attachment 5 for response.

43ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-32Describe the electrical power requirements for Phase 3 of the mitigating strategies integrated plan and provide the capacity of the power sources.APS Response:

The initial electrical loading for FLEX phase 3 is similar to the loading in phase 2 asdescribed in Table 1: Installed Loads Credited in Phase 2, page 53 of the OIP submittal.

The alternative train equipment listed on this table may be powered to continue thestation's coping strategies and provide down time or maintenance time for the primary trainwhen the 4,160 VAC generators are delivered to the station from the Regional ResponseCenters (RRC). The power sources selected for phase 3 are two, 4,160 VAC generators, each rated for 2 megawatts.

These generators will be available to power the 480 VACdistribution buses from the station 4,160 VAC class buses, powering the permanent, essential emergency systems.

Additionally, when the 4,160 VAC generators are available, the opposite train from the initially energized 480 VAC load centers can be energized, increasing flexibility and defense in depth by providing power to an additional train ofequipment used for coping.44ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-33The last paragraph on page 24 of the February 28, 2013, submittal indicates that "corecooling is maintained through once through heat removal from the RCS via coolant boil-off...During this event, a hot leg vent will have been established such that a releasepath is available to support once through via boil-off.

"Discuss the analysis (including

methods, assumptions, and results) to show that corecooling with SG not available can be maintained through once through heat removalfrom the RCS via coolant boil-off.

Include in the discussion:

a. Discussion of how gravity feed flow from the RWT will be monitored andthrottled to match core boiloff under ELAP conditions.

b. Discussion of the timing for providing primary makeup flow via gravity feedfrom the R WT relative to the time of core uncovery under reduced reactorcoolant system inventory conditions.

c. Discussion of what supporting equipment is implied to be operable when asteam generator is considered available to mitigate an ELAP (e.g., turbine-driven auxiliary feedwater pump, main steam relief valves, atmospheric dumpvalves (ADVs)).d. Discussion of scenarios wherein there is neither a hot leg vent nor a steamgenerator available, relative to the guidance of NEI 12-06. The staffunderstands that Generic Letter 88-17 recommended establishing a hot legvent under conditions of reduced reactor coolant system inventory (i.e., waterlevel lower than three feet below the reactor vessel flange),

rather than onthe basis of steam generator availability under ELAP conditions in shutdownand refueling modes. Furthermore, based on the requirement for high-pressure makeup specified for shutdown modes without steam generators inTable 3-2 of NEI 12-06, it is not clear that scenarios without a hot leg ventare considered beyond scope.APS Response:

This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

It has been determined through discussion with NEI that the entry in Table 3-2 of NEI 12-06that requires high pressure makeup to the RCS in shutdown modes without SGs is incorrect.

High pressure makeup is required in Modes 1 through 4, but is not required in Modes 5 or 6.The RCS inventory requirement should have been separated into its own row in the tableand not combined with the core cooling function in Modes 5 and 6 without SGs.45ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-34On pages 27 and 30 of the response dated February 28, 2013, please provide thefollowing items regarding the discussion of core cooling with steam generators notavailable in Phases 2 and 3:a. The basis for concluding that setting makeup flow to the steaming rate plusten percent is sufficient to prevent significant boric acid precipitation in thecore.APS Response:

The minimum portable pump Reactor Coolant system (RCS) make-up flow rate of 1.1 timesthe steaming rate is the plant specific value determined consistent with Reference 12, TableD-1 Core Cooling and Heat Removal (Modes 5 and 6 with steam generators not available) pump sizing and inventory requirement criteria.

The basis for concluding that this flow rateis sufficient to prevent boric acid precipitation is established by performing a boron massbalance for the limiting condition assuming conservative decay heat and other inputs.A boron concentration in the RCS of 50,000 ppm boron is used which is conservatively below the saturated solubility concentration at the reactor coolant boiling point. The limitingsolubility concentration is derived from the boric acid solubility at the boiling point atatmospheric pressure which is equal to 29.3 wt % (Page 2 Reference 38). This value isconverted to ppm boron (1 wt 0/b boric acid = 1748 ppm (Figure 4 Reference 2)) and isequal to a value of 51,216 ppm boron. It is assumed the liquid in the two phase mixture atthe hot side opening will bound the bulk concentration in the core.The make-up boron concentration from the RWT is equal to the maximum 4400 ppm(Surveillance Requirement 3.5.5.3 of, Appendix A of Reference 37). The mass balance forboron at this limiting condition is shown below.m1nq x 4400 ppm = (minj -Mrstra) x 50,000 ppm4400 ppm ((min -mstm) mstm50,000 ppm mini Minimstm 4400 ppm__ =-1raini 50,000 ppmmstmm -n = 4400 ppm = mstm x 1.150,000 ppmWhere:mij= Injection mass flow ratemstm = Steaming mass flow ratem,,n -mstm = Mass flow exiting the RCS as liquid46ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEThe results show that if the injection mass flow rate is 1.1 times the steaming mass flowrate (10% or larger),

the RCS boron concentration would not increase above the limitingconcentration of 50,000 ppm boron.b. The source of borated coolant once the inventory of the refueling water tankis depleted (e.g., reactor grade water, raw water mixed with boric acid).APS Response:

A functional requirement will be that the RCS makeup source is borated reactor gradewater. The long term strategy by which this source of water is established is still underdevelopment.

APS will provide an update to this RAI response in a periodic six-month update.47ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-35Please provide justification that version 4.07 of the MAAP code has adequate capability for performing analysis to demonstrate the integrity of large-dry containments duringELAP conditions.

The justification may include discussion of the adequacy of the code'srelevant models and correlations, benchmarking of code calculations against relevantexperimental data, and relevant comparisons to calculations with state-of-the-art containment analysis codes. The justification may further include the presence ofsignificant margin to acceptance

criteria, if applicable, for scenarios at power as well asduring shutdown and refueling.

APS Response:

This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

48ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-36Please clarify whether the mass and energy leakage to containment determined in thecontainment integrity analysis using the MAAP code are consistent with the predictions of the CENTS code. To the extent that data is available from existing simulations, please include plots comparing integrated mass and energy effluents from the two codeswith and without the availability of the steam generators and provide justification ifsignificant differences exist.APS Response:

This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

49ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-37Please discuss how the MAAP containment analysis models heat losses from the primarysystem to containment and provide justification for its adequacy.

APS Response:

This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

50ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-38Please discuss the quality assurance process under which the MAAP calculations wereperformed.

APS Response:

The MAAP calculations performed in support of this effort were completed under the PVNGSNon-Process Software Quality Assurance Program procedure 80DP-OCCO2.

The MAAP codeis classified as a Category-C qualified code. The engineers performing the calculation haveattended the EPRI/Fauske MAAP training program and are documented as qualified underthe PVNGS qualification guidelines.

The MAAP calculations were independently reviewedand the records of the calculations are retained as life-time plant records.51ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-39Page 16 of the submittal dated February 28, 2013, states, "The actions specified forMode 1 to Mode 4 conditions are bounding when compared to the Mode 5, Mode 6, andfull core offload scenarios because the upper mode scenarios require the mostpersonnel,

actions, and time constraints.

"Please provide the basis for this conclusion (e.g., analyses,

studies, benchmarking, etc.)with particular emphasis on maintaining containment conditions as identified by OpenItem #4.APS Response:

This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

52ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-40Please clarify whether the Open Item Table on page 67 should include pages 40, 41,(potentially) 42, and 43 under Affected Pages by 014 rather than pages 45, 46, and 48.For Open Item #4, please describe the evaluation and/or analysis to be performed, theexpected completion date, and the date the results will be made available to the NRC.APS Response:

The OIP (Reference

7) Open Item Table on page 67, Affected Pages column, should includepages 40 through 43.This RAI was identified as a generic concern or question during the NRC public meeting onApril 18, 2013, regarding the NRC order on mitigating strategies (Order EA-12-049).

Thenuclear industry will resolve this concern generically through the Nuclear Energy Institute (NEI) and the applicable industry groups (e.g., PWROG, EPRI, etc.). Once this concern isresolved, APS will provide an update to this RAI response in a periodic six-month update tothe OIP. NEI will be coordinating with the NRC on the schedule for resolution.

53ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-41Please clarify how the planned strategies for providing makeup to the spent fuel pool willbe implemented while the pool is being cooled by boiling.

For example, as noted onpage 19 of the response dated February 28, 2013, the fuel building rollup door is openedat 11.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. On page 45, the response further notes that, with a full core offload, themost conservative time to boil is 3.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. Finally, pages 45-47 refer to alternate mitigation equipment staging areas and connection points located inside the rollup doorto the fuel building and the need to maintain accessibility to this area. Therefore, pleaseidentify the predicted peak temperature and humidity in the areas where accessibility isrequired during spent fuel pool boiling both prior and subsequent to the fuel buildingrollup door being opened, and confirm that conditions would be tolerable for operators over the expected exposure time for normal and core offload spent fuel heat loads.Provide validation that for escalated SFP boil off or leakage scenarios, implementation strategies include analysis of personnel resource availability to complete actions withinimplementation strategy time limits. Analysis needs to include personnel resourceavailability in consideration for other concurrent activities that also need to be performed site wide.APS Response:

For SFP cooling, two scenarios were evaluated as listed on page 44 of the OIP. Page 45 ofthe OIP lists the time-to-boil values for each case. The SFP decay heat during Mode 1 toMode 6 with the core not off loaded case causes SFP boiling to occur approximately 11.5hours after the initiating event. The SFP decay heat following full core offload case causesSFP boiling to occur approximately 3.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after the event. The sequence of eventstimeline (Page 16 of of the OIP) and associated mitigating strategy time constraints, including page 19 of the OIP, have been identified for the PVNGS Mode 1 to Mode 4 FLEXPlan. Resources for the lower Mode scenarios will be addressed in response to 049-RAI-Palo Verde-39 through NEI and the applicable industry groups.Two connection points exist to provide SFP makeup. The primary location is outside theFuel Building and the alternate location is within the Fuel Building near the rollup door.Both connection points can provide makeup to the SFP while the pool is being cooled byboiling.The location of the alternate connection point is in close proximity to the point of access tothe Fuel Building as described on page 46 of the OIP. The distance from the rollup door tothe connection point will be approximately 5 feet. Figures RAI-41-1 and RAI-41-2 show therelative location of the alternate connection point and the SFP roll-up door on the 100 ft.elevation.

The peak temperature and humidity conditions in the area of the alternate connection pointare expected to be close to outside ambient conditions and will not significantly impactoperator actions.

This is true for times before and subsequent to the Fuel Building rollupdoor opening action time constraints, which are identified as 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> in Table Item 12a ofAttachment 1A of the OIP for Modes 1-4 and 3.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> on Page 45 for full core offloadscenarios.

54ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEThe physical arrangement of the Fuel Building has an influence on the accessibility of thealternate connection location.

Because of the distance in elevation between the SFP leveland alternate connection

location, the SFP boiling phenomenon is not expected to causesignificant temperature and humidity effects at the alternate connection point. Steam, dueto boiling, will rise above the 140 ft. elevation and temperature and humidity in the upperportion of the Fuel Building will be higher than the rest of the building.

The Fuel Buildingroof external low point is specified as elevation 194 ft. and the Fuel Building ceiling internalelevation is approximately 2 ft. below at elevation 192 ft. The SFP operating floor and roofelevations are shown in Figure RAI-41-3.

At the location where the operator connects theportable pump to SFP makeup piping (on the 100 ft. elevation),

the temperature andhumidity are expected to be close to outside ambient conditions.

Also, the large volume ofthe Fuel Building acts as a thermal reservoir and the large surface area allows forcondensation to occur. Both of these features provide thermal benefits that limit theincrease in temperature during time periods when actions within the building would occur.Since only a brief time is required for operators to connect the hoses, operator exposure toany adverse temperature and humidity impacts at the alternate connection location will beminimal.

A pump staging area is designated that is outside the Fuel Building as shown inFigure 3-2 of the OIP.The primary connection point is located on the north side of the Fue Building as shown inFigure 3-11 of the OIP and does not require access to the Fuel Building to connectequipment.

Both connection points will be designed to meet the postulated beyond-design-basis external event conditions described in NEI 12-06 (Reference

12) as applicable toPVNGS.Appropriate staffing levels for listed actions are being coordinated with the site staffingstudy relating to the RAI on Recommendation 9.3, dated March 12, 2012 (Reference 8).The Phase 2 Staffing Study required by Recommendation 9.3 is expected to be submitted in2014 and will further address resources to implement FLEX strategies.

55ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEFIGURESPLANiNORTHTRI'%tORTHROLL-UP DOOR-1 FORM EL.11OLOd'I400 UNIT I-600 UNIT 2800 UNIT3CASK HEAD LAYDOWN.FLOOR EL. 1134-0"LADDER-SPLASH CURTAIN-SPACE RESERVED FORFUTURE HANDLING SLEEVE-(STORED)LFigure RAI-41-1

-Alternate Connection Point Location

-Plan View Elevation 100'-0" (Markup of Reference 13)56ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEESPLASH CURTAIN,I"XCAUST ESSENTIAL

---

.kIR FILTRATION UNITF-HFA-JOt (0IM)ýI.VA.C.

MAINTENANCE lATCH ,. .... IAlternate Connection PointHFL.C. EL9 _" ..FL. EL. 9 1!- 6"Figure RAI-41-2

-Alternate Connection Point Location

-Section View Facing PlantNorth (Markup of Reference 14)57ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEENFigure RAI-41-3

-SFP Operating Floor and Roof Elevations (Markup ofReference 14)58ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-42Page 45 of the submittal dated February 28, 2013, states that diesel driven pumps willbe used to deliver the required flow rate through monitor type nozzles to provide waterto the spent fuel pool. Provide a discussion on the diesel fuel oil supply (e.g., fuel oilstorage tank volume, supply pathway, etc.) for the diesel driven pumps and howcontinued operation to ensure core and spent fuel pool cooling is maintained indefinitely (i.e., Phase 2 and 3).APS Response:

The initial strategy is to fill the phase 2 diesel driven SFP make-up pump from a selectedday tank. Each day tank in the diesel building has a capacity of 1,100 gallons and aTechnical Specification minimum volume of 550 gallons.

The diesel driven pumps andsmaller generators (120 VAC) will be filled using portable fuel containers.

These fuelcontainers will be hand carried to the equipment deployment locations.

These containers are filled from the diesel day tank using a hose attached to the day tank drain line.Additionally, a modification is being planned to provide a connection point at the groundlevel in order to attach a hose, which will be used primarily to fill the MV FLEX (480 VAC)portable generators.

The diesel driven pumps for SFP makeup are not needed for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. At that time,additional personnel will be available to set up and fuel this equipment.

Additionally, after24 hours, fuel deliveries to the site, if needed, can be arranged to maintain on-site fuelsupplies.

Because the portable pumps do not have a recirculation feature they will beoperated in a batch method to raise SFP and SG levels when needed. When they arestopped, at the top of the level band, the pumps may be refueled.

Per page 54 of the OIP, the phase 2 MV FLEX generators will be fueled with a gravity-fed hose from either of the two safety-related diesel day tanks located in the nearby dieselbuilding.

Each MV FLEX generator will be filled with 250 gallons using 550 gallons from oneday tank and leave the other day tank full to allow recovery of the installed Class 1Egenerators.

The MV FLEX generators will consume 36 gal/hr of fuel at 100% load;therefore, 250 gallons will last approximately 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> before requiring refueling.

Once theMV FLEX generators are running, the existing 480 V, 3 hp diesel fuel transfer pump will beavailable, allowing the day tanks to be refilled from the underground 84,000-gallon dieselfuel oil storage tanks. The 4,160 VAC diesel generators will be fueled in the same manneras the 480 VAC generators.

59ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-43Please provide further information, and identify the methods to be used which willprovide the minimum flow rates necessary for the SFP sprays, and account for the ratesrequired for boil off due to the design basis heat load, and postulated losses due toleakage.APS Response:

The make-up flow rate requirement for the SFP at maximum decay heat is 200 gpm. Themake-up flow rate requirement for the SFP due to boil off rate at maximum decay heat isapproximately 100 gpm. The maximum leakage rate from the SFP gate seals is assumed tobe 56 gpm. In total, the minimum make-up pump flow rate should be approximately 160gpm. A safety factor is added to this value so that the recommended make-up pump flowrate is 200 gpm. This is consistent with the minimum 200 gpm flow rate specified by NEI12-06, Table D-3.Redundant 4-inch pipe routings lead to two separate 3-inch sparger lines, which couldprovide make-up water to the SFP. Each 3-inch sparger line has 4 nozzles which discharge water into the SFP. One of the flow path connections is located near the Fuel Building roll-up door. The second flow path connection is located outside the Fuel Building.

Only oneflow path would be used, therefore each system is independent and sized to supply 200gpm. This flow is supplied from either the CST or RWT via fire hose, which is connected tothe suction side of the pump. The pump discharge is connected to the fixed piping at the100 ft. elevation, eliminating the need to access the SFP operating floor (140 ft. elevation).

The discharge nozzles will be in a fixed position at an angle which is selected to ensuresprays do not overshoot the SFP. The ends of the nozzles will be approximately three feet.from the near edge of the SFP and approximately 11 ft. above. Given a flow rate ofapproximately 50 gpm per nozzle and an orifice diameter of 1 inch, the stream will haveample velocity to cover the horizontal distance to reach the SFP.Each flow path is designed for a 200 gpm flow rate and has a ball valve in the flow path toprovide simple flow control (i.e., less flow) if required.

It is not the intention of the designto provide precise flow control, only to provide simple reduction in flow if necessary.

Thepressure drop in each line is calculated at 200 gpm with the valve full open, and the pumpsare sized appropriately to accommodate this design point. Procedural controls will beestablished to batch fill the SFP between level 2 (10 feet above the top of the fuel storagerack) and level 1 (23 feet 4.5 inches above the top of the fuel storage racks) as discussed inNEI 12-02, Industry Guidance for Compliance with NRC Order EA-12-051,

'To ModifyLicenses with Regard to Reliable Spent Fuel Pool Instrumentation,'

Revision 1, dated August24, 2012.60ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED ENCLOSURE APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEE049-RAI-Palo Verde-44Please provide further information that will clarify whether PVNGS uses heat tracing forfreeze protection to conform to NEI 12-06, Section 3.2.2, guideline (12) as endorsed byJLD-ISG-2012-01.

APS Response:

As described in the OIP (page 11 of 119) PVNGS is exempt from extreme cold; therefore, freeze protection is not required.

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1. American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)

Weather Station Data, Luke AFB/Phoenix, AZ, USA, WMO#722785, 2009ASHRAE Handbook

-Fundamentals.

2. Palo Verde Nuclear Generating Station (PVNGS) Design Criteria Manual Part II,Plant Design General Design Criteria Rev. 19.3. Palo Verde calculation 13-MC-SG-0314, Nitrogen tank pressure requirement forADVs.4. Palo Verde administrative procedure 40EP-9EO08, "BLACKOUT."

5. Nuclear Regulatory Commission (NRC) Safety Evaluation Report (SER) letter,"Revised Station Blackout Coping Duration,"

October 31, 2006.6. Arizona Public Service (APS) Document 791S-9ZZ07, Rev. 0, "PVNGS ExtendedLoss of All Site AC Guideline,"

DRAFT.7. APS Letter to US NRC 102-06670-DCM/MAM, "Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530APS Overall Integrated Plan in Response to March 12, 2012 Commission OrderModifying Licenses with Regard to Requirements for Mitigation Strategies forBeyond-Design-Basis External Events (Order Number EA-12-049),"

February 28,2013, (ADAMS Accession Number ML13136A022).

8. NRC Letter, "Request for Information Pursuant to Title 10 of the Code of FederalRegulations 50.54(f),

Regarding Recommendations 2.1, 2.3, and 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident,"

March12, 2012, (ADAMS Accession Number ML12053A340).

9. Nuclear Management and Resources Council (NUMARC) 87-00, Rev 1, Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at LightWater Reactors, August 1991.10. Electric Power Research Institute (EPRI) Report NP-6041-SL Revision 1, "AMethodology for Assessment of Nuclear Plant Seismic Margin",

August 1991.11. Letter, PVNGS to US NRC, "Response to NRC Request for Additional Information (RAI) Regarding Revised Station Blackout Evaluation,"

PVNGS Letter No.102-05513-CE/SAB/DJS, June 9, 2006.12. Nuclear Energy Institute (NEI) 12-06, Revision 0, Diverse and Flexible CopingStrategies (FLEX) Implementation Guide, August 2012 (ADAMS Accession NumberML12242A378).

13. PVNGS Drawing 13-P-ZFL-501, Revision 14, "Fuel Building Equipment Locations Plans," September 8, 2010.66ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

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14. PVNGS Drawing 13-P-ZFL-502, Revision 12, "Fuel Building Equipment Locations Sections,"

September 20, 2006.15. NRC Order Number EA-12-049, Order Modifying Licenses with Regard toRequirements for Mitigation Strategies for Beyond-Design-Basis External Events,March 12, 2012.16. Non-Uniform Steam Generator U-Tube Flow Distribution During Natural Circulation Tests in ROSA-IV Large Scale Test Facility,"

Kukita et al, Nuclear Science andEngineering Vol 99, 1988 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13136AO22).

17. Westinghouse Report WCAP-16175-P-A, Revision.

0, Model for Failure of RCP SealsGiven Loss of Seal Cooling in CE NSSS Plants, April 2007.18. Sulzer Bingham Pumps Inc. Document E12.5.387, Seal Flow and Leakage Reportfor Seal Retrofit for Reactor Coolant Pumps at the Palo Verde Nuclear Generating Station SBPI seal type RCR950B-3, July 1996.19. Westinghouse Report WCAP-17601-P, Revision 1, Reactor Coolant SystemResponse to the Extended Loss of AC Power Event for Westinghouse, Combustion Engineering and Babcock & Wilcox NSSS Designs, January 2013.20. Brookhaven National Labs (BNL) Technical Report W6211-08/99, "Guidance Document for Modeling of RCP Seal Failures,"

August 1999.21. Westinghouse Report CEN-152, Revision.

6.0, "Emergency Procedure Guidelines" December 2012.22. Westinghouse Analysis Report DAR-TDA-12-2, Revision.

0, "Palo Verde Units 1, 2 &F3 Beyond Design Bases Event -Extended Loss of AC Power," December 2012.23. Westinghouse Letter LTR-PCSA-12-78, Rev. 0, "Transmittal of PA-PSC-0965 CoreTeam PWROG Core Cooling Management Interim Position Paper," November 9,2012.24. Westinghouse Calculation CN-FSE-12-10, Rev. 0, "Palo Verde Units 1, 2 and 3Reactor Coolant System (RCS) Inventory, Shutdown Margin, and Mode 5/6 BoricAcid Precipitation Control (BAPC) Analyses to Support the Diverse and FlexibleCoping Strategy (FLEX),"

February 15, 2013.25. Westinghouse Calculation CN-SEE-II-12-33, Rev. 1, "APS Palo Verde NuclearGeneration Station FLEX Conceptual Design AFT Fathom Models,"

April, 3, 2013.26. Palo Verde Nuclear Generating Station Units 1, 2, and 3 "Updated Final SafetyAnalysis Report,"

Revision 16, June 2013.67ATTACHMENTS 4 AND 5 OF THE ENCLOSURE CONTAINProprietary and Security-Related Information

-Withhold under 10 CFR 2.390UPON SEPARATION THIS PAGE IS DECONTROLLED APS RESPONSE TO RAI REGARDING THE PVNGS OIP FOR NRCORDER EA-12-049, MITIGATING STRATEGIES FOR BDBEEATTACHMENT 2REFERENCES

27. NUREG/CR-1699, "Modes of Circulation in an Inverted U-Tube Array withCondensation,"

Griffith, Calia, October 198028. TR-FSE-13-6, Rev. 0, "Palo Verde Nuclear Generating Station FLEX Integrated Plan," February 2013.29. EPRI NP-3471, "Experimental Data Report on Condensation in a Single Inverted U-tube," Banerjee,

Nyguyen, May 1984.30. APS Letter, 162-13357-PSH, Rev. 0, "Data Transmittal of Requested Physics Datafor Palo Verde Unit 3, Cycle 16, End of Cycle to Support Station Blackout CopingEvaluations."

31. EGG-SEMI-5549, "Quick Look Report for SEMISCALE Mod-2A Test S-NC-4,"

D. J.Shimeck et al, August 1981.32. JLD-ISG-2012-01, Rev. 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 (ADAMS Accession No. ML12229A174).

33. NRC Report NUREG-0578, "TMI-2 Lessons Learned Task Force Status Report andShort-Term Recommendations,"

July 1979 (ADAMS Acession No. ML090060030).

34. Oak Ridge National Laboratory Radiation Safety Computational Center CodePackage CCC-750, "SCALE 6: Standardized Computer Analyses for Licensing Evaluation Modular Code System for Workstations and Personal Computers, Including ORIGEN-ARP,"

August 2009.35. APS Letter 448-00774, "Transmittal of data to be used in ORIGEN-ARP SCALEpackage for best estimate decay heat model for the Palo Verde Nuclear,"

H. Mortazavi, July 11, 2012.36. American Nuclear Society, ANSI/ANS-5.1-1979, "Decay Heat Power in Light WaterReactors,"

August 1979.37. Palo Verde Nuclear Generating Station Units 1, 2, and 3 Renewed Operating License (Through Amendment Nos. 191), July 3, 2013.38. Westinghouse Report LOCA-75-127-NP, Revision 0, "Post LOCA Boric Acid MixingEquipment."

[ADAMS Accession Number ML11167A116]

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