ML15065A032

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events (Order No. EA-12-049)

ML15065A032
Person / Time
Site:	Palo Verde
Issue date:	02/27/2015
From:	Mims D Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07005-DCM/TNW/PJ H, EA-12-049
Download: ML15065A032 (16)

Text

EA-12-049 DWIGHT C. MIMS Senior Vice President, Nuclear Regulatory & Oversight 102-07005-DCM/TNW/PJ H Palo Verde Nuclear Generating Station February 27, 2015 P.O. Box 52034 Phoenix, AZ 85072 U.S. Nuclear Regulatory Commission Mail Station 7605 ATTN: Document Control Desk Tel 623 393 5403 11555 Rockville Pike Rockville, MD 20852

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan 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 was immediately effective and directed APS to develop, implement, and maintain guidance and strategies to maintain or restore core cooling, containment, and spent fuel pool cooling capabilities in the event of a beyond-design-basis external event.

Specific requirements are outlined in Attachment 2 of Reference 1.

Reference 1 required submission of an initial status report 60 days following issuance of the final interim staff guidance and an overall integrated plan (OIP) pursuant to Section IV, Condition C. Reference 2 provided the APS initial status report regarding mitigation strategies. In Reference 3, APS provided the PVNGS OIP.

After reviewing the PVNGS OIP for mitigation strategies, the NRC issued a request for additional information (RAI) to APS (Reference 4). On July 18, 2013, APS provided a response to the NRC RAI regarding the PVNGS OIP for mitigation strategies (Reference 5).

Reference 1 also required submission of status reports at 6-month intervals following submittal of the OIP. NEI 12-06, Diverse and Flexible Coping Strategies (FLEX)

Implementation Guide, Revision 0, provides direction regarding the content of the status reports.

Reference 6 provided the APS first 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049) pursuant to Section IV, Condition C.2, of Reference 1.

References 8 and 9 provided the APS second and third 6-Month Status Reports, respectively. Reference 10 provided the APS Notification of Full Compliance with NRC Orders EA-12-049 and EA-12-051 for PVNGS Unit 1.

The NRC issued the Interim Staff Evaluation for the PVNGS OIP on November 25, 2013 (Reference 7).

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway -Diablo Canyon - Palo Verde - Wolf Creek

102-07005-DCM/TNW/PJH ATTN: Document Control Desk U.S. Nuclear Regulatory Commission APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies Page 2 The enclosure to this letter provides the fourth 6-Month status report on the PVNGS OIP for mitigation strategies.

No commitments are being made to the NRC by this letter.

Should you need further information regarding this letter, please contact Thomas Weber, Department Leader, Regulatory Affairs, at (623) 393-5764.

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

Executed on

_/_2_

26__S_

(Date)

Sincerely, DCM/TNW/hsc

Enclosure:

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events cc:

W. M. Dean M. L. Dapas B. K. Singal M. M. Watford C. A. Peabody J. Boska L. M. Regner NRC Director Office of Nuclear Reactor Regulation NRC Region IV Regional Administrator NRC NRR Project Manager for PVNGS NRC NRR Project Manager NRC Senior Resident Inspector PVNGS NRC NRR/MSD Project Manager NRC NRR/JLD/JPMB Project Manager

References:

1.

NRC Order Number EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, dated March 12, 2012

2. APS Letter 102-06614, Initial Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated October 29, 2012

102-07005-DCM/TN W/PJ H ATTN: Document Control Desk U.S. Nuclear Regulatory Commission APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies Page 3

3. APS Letter 102-06670, APS Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated February 28, 2013

4. NRC Letter, 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, dated June 20, 2013

5. APS Letter 102-06733, Response to Request for Additional Information for the PVNGS Overall Integrated Plan in Response to the March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated July 18, 2013

6. APS Letter 102-06758, APS First 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049),

dated August 28, 2013

7. NRC Letter, Palo Verde Nuclear Generating Station, Units 1,2, and 3-Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049-Mitigation Strategies, dated November 25, 2013

8. APS Letter 102-06840, APS Second 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049),

dated February 28, 2014

9. APS Letter 102-06932, APS Third 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049),

dated August 28, 2014

10. APS Letter 102-06985, Notification of Full Compliance with NRC Orders EA-12-049 and EA-12-051 for PVNGS Unit 1, dated January 9, 2015

ENCLOSURE APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events 1 Introduction Arizona Public Service (APS) developed an Overall Integrated Plan (OIP) (Reference 2 in Section 8), documenting the diverse and flexible strategies (FLEX), in response to Reference 1. This attachment provides an update of milestone accomplishments since submittal of the OIP, including any changes to the compliance method, schedule, or need for relief or relaxation and the basis for such changes, if any.

2 Milestone Accomplishments The following milestone(s) have been completed since the development of the OIP, and are current as of February 10, 2015:

Develop Storage Plan: A location for the onsite FLEX Emergency Equipment Storage Facility (EESF) has been selected (See Open Item 1 [OI1] in Section 6 of this enclosure). The EESF will consist of five separate, stand-alone structures that are seismically designed to American Society of Civil Engineers (ASCE) 7-10, Minimum Design Loads for Buildings and Other Structures. The EESF design is complete and construction has started on the seismic concrete storage pads and tie-downs. The initial pad to be used on an interim bases has seismic tie-downs and has been completed. Construction of the EESF to shelter FLEX equipment from the environment will be completed in Fall 2015.

" Completed implementation and provided notification of Full Compliance with NRC Orders EA-12-049 and EA-12-051 for PVNGS Unit 1 on January 9, 2015 (Reference 7).

3 Milestone Schedule Status The following table provides an update to Attachment 2 of the OIP. This section provides the status of each activity and changes to target completion dates. The provided dates are for planning purposes and are subject to change as design and implementation details are developed. Additional changes in target completion dates will be noted in future 6-month status reports.

A number of activities have occurred to validate the feasibility of the mitigation strategies. FLEX strategies were validated using applicable configuration management procedure requirements during development of modification packages. Procedural requirements and instructions were aligned with modifications and staffing analysis.

During and after planned training activities, desktop simulation and plant walk-throughs were performed for FLEX equipment connections and tie-ins to validate the mitigation strategies. FLEX strategies were validated using the NEI FLEX Validation Process (Section 8, Reference 5).

The revised milestone target completion dates do not impact the order implementation date. The Milestone Schedule Status Table below lists the design status of the I

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events modifications by project identification number and design modification work order (DMWO) package numbers.

Revised Target Activity Target Milestone Completion Status Completion Date Date Submit 60 Day Status Report Oct 2012 Complete Submit Overall Integrated Plan Feb 2013 Complete Submit 6 Month Updates:

Update 1 Aug 2013 Complete Update 2 Feb 2014 Complete Update 3 Aug 2014 Complete Update 4 Feb 2015 Complete' Update 5 Aug 2015 Not Started Implementation Preearation:

Develop Strategies Sept 2013 Complete Walk-throughs or Sept 2014 Complete Demonstrations 2

Complete Perform Staffing Analysis May 2014 (Section 8, Reference 6)

Modifications:

Modifications Evaluation Feb 2013 Complete Units 1, 2, and 3 Engineering Sept 2014 Complete Design Work (Mod Design Status)

AF-1626 Steam Generator Mar 2014 Complete Injection via Auxiliary Feedwater (AF) System (DMWO 4345882)

AF-1633 Equipment Hatch Feb 2014 Complete Opening to "A" AF Room for Access and Ventilation (DMWO 4345887)

CH-1624 Reactor Water Tank Dec 2013 Complete Tie-In (DMWO 4345884)

CT-1625 Condensate Storage Dec 2013 Complete Tank Tie-In (DMWO 4345885)

DG-1634 Fuel Oil Day Tank Aug 2013 Complete Gravity Drain (DMWO 4345888)

PB-1630 Electrical Apr 2014 Complete Connection to 4160kV and 480V (DMWO 4304157) 2

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events Target Revised Tilestone Completion Activity Target ltC e Status Completion Date Date PB-1648 Electrical Sept 2014 Started3 Dec 2015 Connection to 4160kV Calvert Bus (DMWO 4491931)

PC-1629 Pool Cooling Jan 2014 Complete Electrical, Spent Fuel Pool Remote Fill, Alternate Gas for Gate Seals and Deployment Pads (DMWO 4345883)

SI-1627 Reactor Coolant Jan 2014 Complete System Makeup via High Pressure Safety Injection (DMWO 4304156)

Unit 1 Implementation Outage Nov 2014 Complete Unit 2 Implementation Outage Nov 2015 Not Started Unit 3 Implementation Outage May 2015 Not Started Onsite Storage:

Develop Storage Plan Jul 2013 Complete Temporary Pads with Seismic Tie-downs Installed (For Unit 1 Nov 2014 Complete and N+1 Implementation)

EESF Complete Fall 2015 Started Sept 2015 Protected Area Pads for FLEX Equipment Deployment Installed FLEX Equipment:

Procure On-Site Equipment Unit 1 and N+1 Oct 2014 Complete Unit 2 Oct 2015 Started Unit 3 April 2015 Complete Both of the National Strategic Alliance for FLEX Emergency Sept 2014 Complete Response (SAFER) Response Centers Operational Select Staging Area 'C' - Offsite Staging Area for Phase III FLEX equipment. It is the area where the Phase III portable equipment Sept 2014 Complete is readied for transport to the plant site.

3

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events Revised Target Activity Target Milestone Completion Status Completion Date Date Procedures:

PWROG issues NSSS-specific May 2013 Complete guidelines (Modes 1 - 4)

Develop FSGs4 Sept 2014 Complete Create Administrative &

Oct 2014 Complete Maintenance Procedures Training:

Develop Training Plan Mar 2014 Complete Implement Training Sep 2014 Complete Full Implementation:

Unit 1 FLEX Implementation Nov 2014 Complete Unit 2 FLEX Implementation Nov 2015 Not Started Unit 3 FLEX Implementation May 2015 Not Started Submit Full Compliance Report Unit 1 Jan 2015 Complete Unit 2 Mar 2016 Not Started Jan 2016 Unit 3 Sept 2015 Not Started July 2015 Submit Final Integrated Plan Apr 2016 Not Started 1 The Fourth 6-Month update is complete with this submittal. The milestone schedule dates in Attachment 2 of the Order required updating as described in Section 3.

2 Desktop simulation and plant walk-throughs 3 Modification is not required for Phase II or III FLEX Strategy. Equipment is for recovery phase. Implementation is pending and schedule will be dependent on availability of materials needed for modification.

4 Includes Basis Document and Procedures for all operating Modes 5The strategies have been completed for all 3 Units, any differences will be noted in future 6-Month update.

4 Changes to Compliance Method There are no changes to the compliance method as documented in the OIP.

5 Need for Relief/Relaxation and Basis for the Relief/Relaxation APS expects to comply with the order implementation date and no relief or relaxation is requested at this time.

4

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events 6 Open Items from Overall Integrated Plan and Interim Staff Evaluation The following tables provide a summary of the open and confirmatory items documented in the OIP and the Interim Staff Evaluation (ISE) and the status of each item for the Palo Verde Nuclear Generating Station (PVNGS).

Overall Integrated Plan Open Items Status OIl-A storage location for FLEX equipment needs to be selected.

Complete Location has been selected for FLEX equipment storage. The FLEX Emergency Equipment Storage Facility (EESF) will be located true west of the new Protected Area (PA) warehouse (outside of the PA but inside the Security Owner Controlled Area) and true east of the helicopter pad (See Section 9 Figure 1).

Additional details on the locations of the temporary pad, FLEX EESF, and Helipad are included in Figure 2 (See Section 9 Figure 2).

012-PVNGS FSG is currently a draft document and Complete will need to be finalized. Existing site EOPs will need to be updated to direct use of the PVNGS Extended Activities have been completed Loss of All Site AC Guideline during an ELAP.

as scheduled and noted, as Additionally, a program and procedural control applicable, on the Milestone process is under development and will be Schedule Status Table in Section implemented to meet the requirement of NEI 12-06 3 of this enclosure.

(Reference 3).

013-Structure, content, and details of the National Complete SAFER Response Center Phoenix playbook, and location of the offsite staging area will be determined.

The contract agreement and the Response Plan template with PVNGS-specific information have been issued. The National SAFER Response Center Phoenix has been designated to be the Staging Area 'C' location.

5

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events Overall Integrated Plan Open Items Status 014-Additional strategies to maintain containment Complete conditions during Modes 5 and 6 ELAP will be evaluated.

The Nuclear Energy Institute (NEI) generic guidance (Reference 4) has been incorporated in FSGs.

Interim Staff Evaluation Status Open Items' 3.1.1.2.A - Means to move equipment.

Complete In its Integrated Plan, APS has identified that there is APS response has been provided a time constraint 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 for NRC review in the STARS kW 480 V generators in order to recharge batteries.

Alliance website e-portal.

APS has not identified a means to move the generators along with the concomitant method for reasonable protection of that means from the identified hazards applicable to PVNGS as would be required to conform to the guidance of NEI 12-06, Section 5.3.2, consideration 5 and Section 9.3.2.

3.2.1.2.A - RCP Seal Leakage Rate Complete The licensee was requested to provide RCP seal APS response has been provided leakage testing data applicable to ELAP conditions for NRC review in the STARS for Palo Verde and show the following:

Alliance website e-portal.

(a) the calculated maximum RCP seal leakage of 17 gpm/seal exceeds the RCP seal leakage rate obtained from the RCP seal testing data, and (b) the assumed maximum seal gap increase of 0.01 inches exceeds the seal gap increase obtained from the RCP seal testing data. The testing data used to support the calculated maximum leakage rate and the assumed maximum increase in the seal gap should be applicable to Palo Verde seals (with respect to the seal design and material, and seal cooling system),

and ELAP conditions (in terms of the maximum temperature and pressure conditions) for an extended testing period consistent with the ELAP coping time.

3.2.1.2.B - Operating Conditions Complete To determine whether the licensee adequately APS response has been provided addressed the information discussed in Section 3.2.1.2 for NRC review in the STARS 6

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events Interim Staff Evaluation Open Items' Status of this evaluation relating to Section 4.4.2 of WCAP-17601, the NRC staff requested the licensee to provide the following information.

(a) Confirm whether an instruction step is available or not for the operator to maintain the subcooled margin which is credited for an ELAP event. If the procedure step is not available, provide justification.

(b) Justify the following statement that was used to satisfy criterion (b) discussed in Section 3.2.1.2 of this evaluation: "... the temperature must reach 460 OF at the inlet of the Fourth stage seal prior to posing a pop open concern."

Alliance website e-portal.

1An Interim Staff Evaluation has been received from the NRC (Reference 4).

Interim Staff Evaluation Confirmatory Items' Status 3.1.1.4.A - Utilization of offsite resources.

APS Actions Complete.

APS has provided information regarding its use of the APS is using the National offsite resources through the industry SAFER SAFER Response Center program, and identified the local staging area, but Phoenix facility as the Staging needs to provide details on transportation to the site Area 'C' and the SAFER Team following a seismic event, will supply the transport vehicles to move the equipment to the PVNGS site.

3.2.2.A - SFP cooling makeup flow rates.

Complete Table A of Reference 18 identifies a performance The value of 110 gpm in Table A criterion of 110 gpm for the identified SFP makeup of Reference 18 is incorrect. SFP pumps. This flow rate is lower than the identified makeup FLEX pump and minimum flow rate to compensate for boil off due to delivery system is designed to the design basis heat load and postulated losses due to provide 200 gpm.

leakage, which total 131 gpm. The licensee stated they would change this to provide at least 200 gpm The OIP is Reference 18 of the per pump. Confirm this change.

APS response cited in this RAI and was provided to the NRC by Reference 2 of this enclosure.

7

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events Interim Staff Evaluation Confirmatory ItemsI Status 3.2.3.A - Containment Functions Strategies.

Complete Consistent with the resolution of Open Item APS response has been provided 3.2.1.2.A, ensure that the finalized containment for NRC review in the STARS analysis properly utilizes the correct RCP seal Alliance website e-portal.

leakage values and the mass/energy values consistent with the approved CENTS analysis.

3.2.4.2.A - Ventilation of main control room.

Complete In its Integrated Plan, APS has presented insufficient APS response has been provided information for the NRC staff to conclude that the for NRC review in the STARS habitability limits of the control room will be Alliance website e-portal.

maintained in all phases of an ELAP.

3.2.4.8.A - Portable equipment instrumentation.

Complete In its Integrated Plan, APS stated that instrumentation APS response has been provided will be provided for portable equipment operation.

for NRC review in the STARS The NRC staff requested the licensee to describe the Alliance website e-portal.

instrumentation that will be used to monitor portable/FLEX electrical power equipment including their associated measurement tolerances/accuracy in order to support a conclusion that the equipment will be capable of being operated in a manner to protect installed equipment from adverse electrical interactions in conformance with the guidance of NEI 12-06, Section 3.2.2, guideline (13), as endorsed by JLD-ISG-2012-01. The licensee committed to provide this in a future update.

3.2.4. 10.A - Battery Duty Cycle.

APS Action Complete.

During the audit process, the licensee stated that the APS has implemented NEI FLEX strategy station battery run-time was calculated position paper entitled EA in accordance with the IEEE-485 methodology using 049 Mitigating Strategies manufacturer discharge test data applicable to the Resolution of Extended Battery licensee's FLEX strategy as outlined in the NEI Duty Cycles Generic Concern, position paper entitled "EA-12-049 Mitigating ADAMS Accession No.

Strategies Resolution of Extended Battery Duty ML13241A186.

Cycles Generic Concern," ADAMS Accession No. ML13241A186. The NRC staff will evaluate a licensee's application of the guidance (calculations 8

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events Interim Staff Evaluation Status Confirmatory Items' and supporting data) in its development of the final APS Action Complete.

Safety Evaluation documenting compliance with NRC Order EA-12-049.

An Interim Staff Evaluation has been received from the NRC (Reference 4).

U1 Full Compliance Letter 102-06985, dated Status January 09, 2015, pending RAIs:

RAI-33-B Working Discuss the analysis (including methods, RAI 33-B was identified as a assumptions, and results) to show that core cooling generic concern or question with SG not available can be maintained through once during the NRC public meeting through heat removal from the RCS via coolant boil-on April 18, 2013, regarding the off.

NRC order on mitigating strategies (Order EA-12-049).

The nuclear industry will resolve this concern generically through the applicable industry groups (e.g., PWROG, EPRI, etc.).

Once this concern is resolved, APS will provide an update to this RAI response in a periodic six-month update.

RAI-34-B Working Provide the following items regarding the discussion RAI 34-B was identified as a of core cooling with steam generators not available in generic concern and the nuclear Phases 2 and 3:

industry will resolve this concern generically through the

b. The source of borated coolant once the inventory of applicable industry groups (e.g.,

the refueling water tank is depleted (e.g., reactor PWROG, EPRI, etc.). Once this grade water, raw water mixed with boric acid).

concern is resolved, APS will provide an update to this RAI response in a periodic six-month update.

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

9

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events 8 References The following references support the updates to the PVNGS OIlP described in this enclosure:

1. NRC Order Number EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, dated March 12, 2012 (ML12054A735)

2. APS Letter 102-06670, APS Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated February 28, 2013 (ML13136A022)

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

4. NRC Letter, Palo Verde Nuclear Generating Station, Units 1,2, and 3-Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049-Mitigation Strategies, dated November 25, 2013 (ML13308C153)

5. NEI APC 14-17, FLEX Validation Process, dated July 18, 2014

6. APS Letter 102-06885, APS Submittal for Fukushima Response NEI 12-01 of Phase 2 Staffing Assessment Report, dated June 11, 2014

7. APS Letter 102-06985, Notification of Full Compliance with NRC Orders EA 049 and EA-12-051 for PVNGS Unit 1, dated January 09, 2015 (ML15012A444) 10

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events 9 Figures Helicopter Pad Location of the FLEX EESF Figure 1 11

APS Fourth 6-Month Status Report on the PVNGS Overall Integrated Plan for Mitigation Strategies for Beyond-Design-Basis External Events U1 & (N+1) Temporary Equipment Seismic Storage Pad IN Figure 2 12