View source for L-15-074, FENOC, Perry Nuclear Power Plant - Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force (NTTF) Review of Insights from the Fukushima Dai-ichi Ac

{{Adams
| number = ML15069A056
| issue date = 03/10/2015
| title = FENOC, Perry Nuclear Power Plant - Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force (NTTF) Review of Insights from the Fukushima Dai-ichi Ac
| author name = Harkness E
| author affiliation = FirstEnergy Nuclear Operating Co
| addressee name = 
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000440
| license number = NPF-058
| contact person = 
| case reference number = L-15-074
| document type = Letter type:L
| page count = 39
| project = 
| stage = Response to RAI
}}

=Text=
{{#Wiki_filter:FENOC'                                                                                    Perry Nuclear Power Plant P.O. Box 97 10 Center Road Perry, Ohio 44081 FirstEnergy Nuclear Operating Company ErnestJ. Harkness                                                                                     440-280-5382 Vice President                                                                                   Fax: 440-280-8029 March 10, 2015 L-15-074                                                               10 CFR 50.54(f)
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852

==SUBJECT:==

Perry Nuclear Power Plant Docket No. 50-440, License No. NPF-58 FirstEnergy Nuclear Operating Company (FENOC) Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force (NTTF) Review of Insights from the Fukushima Dai-ichi Accident On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued a letter titled, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 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," to all power reactor licensees and holders of construction permits in active or deferred status. Enclosure 2 of the 10 CFR 50.54(f) letter addresses NTTF Recommendation 2.1 for flooding. One of the required responses is for licensees to submit a Hazard Reevaluation Report (HRR) in accordance with the NRC's prioritization plan. By letter dated May 11, 2012, the NRC placed the Perry Nuclear Power Plant (PNPP) in Category 3 requiring a response by March 12, 2015. The Flood HRR for PNPP is enclosed.
As discussed in the enclosed report, three flood levels (riverine, local intense precipitation and probable maximum storm surge) determined during the hazard reevaluation exceed the current licensing basis (CLB) flood levels. Actions planned to address the reevaluated hazards are also described in the enclosed report.

Perry Nuclear Power Plant L-15-074 Page 2 In accordance with the guidance provided by NRC letter dated December 3, 2012, titled "Trigger Conditions for Performing an Integrated Assessment and Due Date for Response," an integrated assessment is required if flood levels determined during the hazard reevaluation are not bounded by the CLB flood levels. The 10 CFR 50.54(f) letter specifies that the integrated assessment be completed and a report submitted within two years of submitting the HRR. Therefore, FENOC intends to submit an Integrated Assessment Report for PNPP prior to March 12, 2017.
There are no regulatory commitments contained in this letter. If there are any questions or if additional information is required, please contact Mr. Thomas A. Lentz, Manager -
Fleet Licensing, at 330-315-6810.
I declare under penalty of perjury that the foregoing is true and correct. Executed on March Id , 20 15.
Respectfully,
~~-
Ernest J. Harkness

==Enclosure:==

Flood Hazard Reevaluation Report cc:   Director, Office of Nuclear Reactor Regulation (NRR)
NRC Region Ill Administrator NRC Resident Inspector NRR Project Manager

Enclosure L-15-074 Flood Hazard Reevaluation Report (36 pages follow)

FLOODHAZ/ARDREEVALUATIOil                                   REPORT IN RESPONSE  TO THE50.5/T(f}            INFORUATION                  REQUESTREGARDING NEAR-TERI'TASKFORCERECOHTENDATION                                      2.I: FLOODING for ths PERRYHUCLEARPOWERPLANT f 0 Ctnttr Road North Perry,OH {4081 Firret      EnergyCorporation 76 SouthMainStreet Akron,OH44308 Preparad       by:
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NTTF Recommendation               2.1 (HazardReevaluations):         Flooding                    Revision    0 FirstEnergyCorporation                                                                     February23,2015 Table of Gontents 1 . P U R P O S.E      .                                                                                 ......3 1 . 1 . B a c k g r o u .n d                                                                      ..........3 1.2. Requested            Actions..                                                               ..........3 1.3. Requested            Information                                                               ...-.-..4
: 2. SITEINFORMATION                                                                                       ......5 2 . 1 . C u r r e nDt e s i g n Basis..                                                           ..........7 2.1.1. LocalIntense              Precipitation    (LlP).....                                       ......7 2.1.2. Flooding           in Streams        andRivers                                              ......7 2.1.g. DamBreaches                 andFailures 2.1.4. StormSurgeandSeiche...                                                                      ...'..7 2.1.5. Tsunami......                                                                                .....7 2 . 1 . 6 . l c e - l n d u c eFdl o o d i n g                                                  .........7 2.1.7. Channel            Migration     or Diversion                                              ..,....7 2.1.8. Combined             EffectFlood(including       \Mnd-Generated  Waves)                ...........8 2.1.9. LowWater 2.2. Flood-Related            Changes        to the LicenseBasis                                      ......8 2.3. Changesto theWatershed                      andLocalAreasinceLicenselssuance                      .....8 2.4. CurrentLicensing              BasisFloodProtection         andPertinent             Features............8 FloodMitigation
: 3. 

==SUMMARY==
OF FLOODHATARD                 REEVALUATION                                     ........9 3.1. Floodingin Streamsand Rivers(Reference                        PNPP2015a,PNPP2015b,PNPP2015c, PNPP2015d,PNPP2015e,PNPP2015f                          , PNPP   2015n,PNPP2015r,andPNPP2015s)........10 3.1.1. Basisoflnputs:...                                                                     ..........11 3.1.2. Computer             Software       Programs                                               ....-12 3.1.3. Methodology                                                                                 ....12 3.1.4. Results                                                                                  .......16 3.2. DamAssessment                 (Reference      PNPP2015h) 3 . 2 . 1 . B a s i so f I n p u t s . . . .                                                      .....18 3.2.2. Computer             Software       Programs                                                ....18 3.2.3. Methodology                                                                                 ....1I 3.2.4. Results                                                                                  .......1I 3.3. lce-lnduced           Flooding     (Reference     PNPP2015i)                                  ....'..18 3 . 3 . 1 . B a s i so f I n p u t s . . . .                                                       ....18 3.3.2. Computer             Software       Programs                                             .......18 3.3.3. Methodology                                                                                  ...18 3.3.4. Resutts                                                                                  ....'..19 3.4. ChannelMigration                or Diversion    (Reference  PNPP2015i)                           ...'20 PERRYNUCLEARPOWERPLANT                                                                         Page1 of 35

NTTFRecommendation               2.1 (HazardReevaluations):   Flooding                  Revision0 FirstEnergyCorporation                                                             February23,2015 3 . 4 . 1 . B a s i so f I n p u t s . . . .                                                 ...20 3.4.2. Computer             Software        Programs                                      ......24 3.4.3. Methodology                                                                           ...20 3.4.4. Results                                                                              ....20 3.5. StormSurge(Reference                     PNPP2015j,PNPP2015k,PNPP20151, PNPP2A15o,andPNPP 2015p)                                                                                         ...20 3 . 5 . 1 . B a s i so f l n p u t s . . . .                                            ........21 3.5.2. Computer             Software        Programs                                      ......21 3.5.3. Methodology                                                                         .....21 3.5.4. Results                                                                              ....23 3.6. Tsunami       Assessment            (Reference  PNPP2015m).                              ....24 3 . 6 . 1 . B a s i so f I n p u t s . . . .                                                ....24 3.6.2. Computer             Software        Programs                                     .......24 3.6.3. Methodology                                                                           ...24 3.6.4. Results                                                                            ......25 3.7. Combined          EffectFlood(including         \Mnd-Generated              PNPP2015q)...26 Waves)(Reference 3.7.1. Basisoflnputs....                                                                    ....26 3.7.2. Computer             SoftwarePrograms                                                 ...27 3.7.3. Methodology                                                                         .....27 3.7.4. Results                                                                            ......27 3.8. LocalIntensePrecipitation                  (Reference PNPP20159)                          .....28 3 . 8 . 1 . B a s i so f I n p u t s . . . .                                                 ...28 3.8.2. Computer             Software        Programs             .......                   .....28 3.8.3. Methodology                                                                           ...28 3.8.4. Results                                                                             .....29
: 4. COMPARISON             WITHCURRENT               DESIGN BASIS...                          .......29
: 5. INTERIM      ANDPLANNED                FUTURE     ACTIONS                                 .......33
: 6. REFERENCES                                                                                 ......34 PERRYNUCLEARPOWERPLANT                                                                 Page2 of 35

NTTFRecommendation        2.1 (HazardReevaluations):    Flooding                         Revision 0 FirstEnergyCorporation                                                            February 23,2015
: 1. PURPOSE 1.1. Background In response to the nuclearfueldamageat the Fukushima        Dai-ichipowerplantdueto the March 11, 2011 earthquakeand subsequenttsunami,the United States Nuclear Regulatory Commission    (NRC)established       the NearTerm Task Force(NTTF)to conducta systematic reviewof NRC processes        and regulations, and to makerecommendations      to the NRCfor its policydirection.The NTTFreporteda set of recommendations          thatwereintendedto clarifyand strengthen  the regulatory  frameworkfor protection   againstnaturalphenomena.
On March12,2012the NRCissuedan information              requestpursuantto Title10 of the Codeof FederalRegulations,    Section50.54(f) (10CFR50.54(0or 50.54(Dletter)whichincludedsix (6) enclosures:
: 1. NTTF Recommendation        2.1:Seismic
: 2. NTTF Recommendation        2.1: Flooding
: 3. NTTF Recommendation        2.3:Seismic
: 4. NTTF Recommendation        2.3:Flooding
: 5. NTTF Recommendation        9.3:EP
: 6. Licensees andHoldersof Construction      Permits fn Enclosure2 of the NRC-issued       informationrequest(Reference    NRCMarch2A12),the NRC requestedthat licenseesreevaluatethe floodinghazardsat their sites againstpresent-day regulatory guidanceand methodologies        beingusedfor earlysite permits(ESP)and combined operatinglicensereviews.
On behalfof FirstEnergy     NuclearOperating    Company(FENOC)for the PerryNuclearPower Station  (PNPP),   this Flood HazardReevaluation        Report(Report)providesthe information requestedin the March 12, 2012 50.54(Dletter;specifically,       the informationlistedunderthe "Requested   Information"  sectionof Enclosure   2, paragraph  1 ('a'through'e').The "Requested fnformation" sectionof Enclosure2,      paragraph2 ('a'through'd'),IntegratedAssessment  Report, will be addressed   separately   if the currentdesignbasisfloodsdo not boundthe reevaluated hazardfor all flood-causing   mechanisms.
1.2. RequestedActions Per Enclosure   2 of the NRO-issued     informationrequest,50.54(0letter,FENOCis requested     to performa reevaluation   of all appropriate externalfloodingsourcesfor PNPP,including  theeffects fromlocalintenseprecipitation     (LlP)on the site,the probable maximum   flood(PMF)on streams and rivers,lake floodingfrom stormsurges,seiches,and tsunamis,and dam failures.lt is requested  thatthe reevaluation    applypresent-day  regulatoryguidance  andmethodologies  being usedfor ESPs,combinedoperatinglicensereviews,and calculation            reviews  includingcurrent techniques,  software, andmethods      usedin present-day standard engineeringpracticeto develop the floodhazard.The requestedinformation       will be gatheredin Phase1 of the NRCstaffstwo-phase processto implementRecommendation               2.1, and will be used to identifypotential "vulnerabilities"(seedefinitionbelow).
PERRYNUCLEARPOWERPI-ANT                                                                Page 3 of 35

NTTFRecommendation        2.1 (HazardReevaluations):   Flooding                           Revision0 FirstEnergyCorporation                                                            February23,2Q15 The NRC prioritization    of responsesletter(ReferenceNRC May 2012)identifiesPNPPas a Category3 site.Licensees      in thiscategoryareexpectedto reportthe resultsof the reevaluation withinthreeyearsof the March12,201250.54(f)letterissuance.
Forthe siteswherethe reevaluated        floodexceedsthe designbasis,addressees       are requested to submitan interimactionplan documenting          plannedactionsor measuresimplemented         to addressthe reevaluated     hazards.
Subsequently,   addressees    shallperforman integratedassessment      of the plantto fullyidentify vulnerabilitiesanddetailactionsto addressthem.Thescopeof the integrated        assessment   report will includefullpoweroperations      andotherplantconfigurations  thatcouldbe susceptible   dueto the statusof the floodprotection    features.Thescopealsoincludesthosefeaturesof the ultimate heatsink(UHS)thatcouldbe adverselyaffectedby floodconditions(thelossof UHSfromnon-flood associatedcausesis not included).lt is also requestedthat the integratedassessment addressthe entiredurationof thefloodconditions.
A definitionof vulnerabilityin the contextof Enclosure2 is as follows:Plant-specificvulnerabilities are thosefeaturesimportantto safetythatwhensubjectto an increased         demanddueto thenewly calculatedhazardevaluationhave not been shown to be capableof performingtheir intended functions.
1.3. RequestedInformation PerEnclosure    2 of the NRC-issued              request50.54(D information                letter,the Reportshouldprovide documented    results,as well as pertinentPNPPinformation       and detailedanalysis,and include the following:
: 1. Site information    relatedto the flood hazard.Relevantstructure,systems,and components (SSCs)important    to safetyandthe UHSare includedin the scopeof thisreevaluation,       and pertinentdataconcerning      theseSSCsshouldbe included.Otherrelevantsite        data include thefollowing:
: 1. Detailedsite information(both designed and as-built),includingpresent-daysite layout,elevationof pertinentSSCs importantto safety,sitetopography,and pertinent spatialandtemporaldatasets;
: 2. Currentdesignbasisfloodelevations      for allflood-causingmechanisms;
: 3. Flood-related   changesto the licensingbasis and any flood protectionchanges (including  mitigation) sincelicenseissuance;
: 4. Changesto thewatershed        andlocalareasincelicenseissuance;
: 5. Currentlicensingbasisfloodprotection      and pertinentfloodmitigation  featuresat the site;and
: 6. Additional  sitedetails,as necessary, to assessthefloodhazard(e.g.,bathymetry     and walkdownresults).
: 2. Evaluation   of the flood hazardfor eachflood-causing      mechanism,    basedon present-day methodologies    and regulatoryguidance.Providean analysisof each flood-causing mechanism   thatmayimpactthesite,including      LIPandsitedrainage,   floodingin streamsand rivers,dam breachesandfailures,stormsurgeand seiche,tsunamis,channelmigration              or diversion,and combinedeffects.Mechanisms          that are not applicable at the site may  be screenedout; however,a justificationshould be provided.A basis for inputs and PERRYNUCLEARPOWERPLANT                                                                   Page 4 of 35

NTTFRecommendation       2.1 (HazardReevaluations):   Flooding                              Revision0 FirstEnergyCorporation                                                            February23,2415 assumptions,   methodologies  and modelsused,includinginputand outputfiles,and other pertinent datashouldbe provided.
: 3. Comparison    of currentand reevaluated    flood-causing  mechanisms    at the site.Providean assessment   of the currentdesignbasisfloodelevationto the reevaluated       floodelevationfor eachflood-causing    mechanism. Includehowthe findingsfrom Enclosure         2 of the 50.54(D letter(i.e.,Recommendation    2.1, floodhazardreevaluations)    supportthisdetermination. lf the current design basis flood bounds the reevaluatedhazard for all flood-causing mechanisms,   includehowthisfindingwasdetermined.
4 . Interimevaluation   and actionstakenor plannedto addressany higherfloodinghazards relativeto the designbasis,priorto completionof the integratedassessmentdescribed below,if necessary.
5 . Additionalactionsbeyondrequestedinformation          item 1.d taken or plannedto address floodinghazards,if any.
: 2. SITEINFORMATION PNPPis locatedin LakeCounty,Ohio,approximately          sevenmilesnortheast    of Painesville. The southernplantsiteboundarylineis 3,100feetfromthe shoreline          of Lake  Erie  on the  westside of the site and 8,000feet on the east side (USAR,Section2.4.1.1).Lake Erie is the major hydrologic  featureof the location.In the vicinityof the site,the coastalwatershed     is drainedby severalsmallstreams(USAR,Section2.4.1.2).        Twonameless,     parallelstreamsruncloseto the plantarea.The larger(MajorStream)has a drainagebasinof 7.16 squaremilesand runs northwestward   within1,000feetof the southwest    cornerof the plant.Thesmallerstream(Minor Stream), whichhasa drainageareaof only0.76squaremiles,borderstheplantareato theeast.
The safety-related   structuresof the plantare locatedwithinthe drainagebasinof the small stream.Finalgradeelevations     in the immediate   plantareavaryfrom617 to 620 feet (USGS)
(USAR,Section2.4.2.2). Thefloorsat plantgradearesetat Elevation     620.5feet(USGS)(USAR, Section2.4.2.3). NotethattheUpdatedSafetyAnalysisReport(USAR)presents              elevations using a USGSdatumthatis equivalent       to the NationalGeodetic    VerticalDatum   of  1929  (NGVD   29).
Thepresent-day    sitelayoutis shownin Figure2.0.1.
PERRYNUCLEAR        POWERPLANT                                                            Page5 of 35

NTTF Recommendation                           Flooding

===2.1 (HazardReevaluations)===
Revision0 FirstEnergyCorporation                                          February23,2015 Figure2.0.1- Present-DaySite Layout PERRYNUCLEAR    POWERPLANT                                          Page 6 of 35

NTTFRecommendation      2.1 (HazardReevaluations): Flooding                        Revision0 FirstEnergyCorporation                                                     February23,2015 2,1. CurrentDesignBasis The currentdesignbasisis definedin the PNPPUSAR.The followingis a listof flood-causing mechanisms    and theirassociatedwatersurfaceelevationsthat wereconsidered   for the PNPP currentdesignbasis.
2.1.1. LocalIntensePrecipitation    (LlP)
The USARindicates                        valueof 26.7inchesovera 6-hourperiod,withthe that the precipitation maximumhourlyrainfallof 13.1inchesoccurringduringthe first hour,is utilizedfor the LIP analysis.In the caseof complete blockage of thestormdrainagesystem,the plantsitehasbeen gradedso thatoverlanddrainage    willoccurawayfromthe plantsitebuildings  andwillnotallow the accumulated  stormwaterto exceedElevation   620.5feet(USGS)(USAR,Section2.4.2.3).
2.1.2. Floodingin Streamsand Rivers The USARidentifiesa flow rateof 31,250cubicfeet per second(cfs)for the MajorStreamand 7,000cfsfortheMinorStream(USAR,Section2.4.3).TheMajorStreamwatersurfaceelevation upstreamof the plantaccessroadfor the PMFwas foundto be 624.0feet (USGS)untilthis surfacemet the normaldepthof flow in the existingstream.This watersurfaceelevationwill safelypassbeneaththerailroadbridge(USAR,Section2.4.3.5\. TheMinorStreamwatersurface efevationwasfoundto be 619.5feet(USGS)(USAR,Figure2.4-8).
2.1.3. DamBreachesand Failures The USARidentifiesno impoundments       upstreamof the plant.Therefore,  dam failureis not includedas a designcondition  (USAR,  Section 2.4.4).
2.1.4. StormSurgeand Seiche Theprobable   maximum   meteorologicaleventin LakeErieresultsin a maximum stillwatersurface etevationof 580.5feet(USGS)(USAR,Section2.4.5.2.2). Theprobablemaximum      storm(PMS) was assumedto occurovera 72-hourperiod,duringwhichthe windsincreasedfrom 20 miles per hourto the maximumspeedof approximately       103 milesper houroverthe lakeand then decreased  to lessthan35 miles hourin the Perryarea(USAR,Section2.4.5.1.3).
per 2.1.5.Tsunami Sincethe site is locatedon LakeErie,an inlandlake,tsunamioccurrence not applicable (USAR,Section2.4.6).
2.1.6. lce-lnducedFlooding lce floodingcannotoccurbecauseof the highbluffsbetweenthe buildings     andthe lake.Also, safety-related onshorebuildingsare set backfromthe top  of the 4S-foothigh bluffto preclude iceforcesbeinga problem(USAR,Section2.4.7.4).
2.1.7. ChannelMigrationor Diversion Channeldiversionis not applicable  to PNPPsinceno coolingwaterchannelsexistfromwhich ffowcouldbe diverted(USAR,Section2.4.9).
PERRYNUCLEARPOWER PLANT                                                          Page 7 of 35

NTTFRecommendation       2.1 (HazardReevaluations):    Flooding                          Revision0 FirstEnergyCorporation                                                           February  23,2415 2.1.8. CombinedEffectFlood(includingWind-Generated              Waves)
   \Mndwaveactivity,includingrunup,wasevaluated        as partof thesurgeanalysis.Runupoccurring coincidentally with the probablemaximumsetupwouldextendto aboutelevation607.9feet (USGS)on the bluffat the lakeshore(USAR,Section2.4.2.2).
2.1.9. Low Water No wateris takenfromthe MajorStreamor MinorStream.Therefore,low flowsin the streams willnotaffectPNPPoperation.
The UHSfor PNPPis LakeErie.Submerged             offshoreintakessupplywaterto the emergency servicewaterpumphouse.      All safety-relatedpumpsandequipmentare locatedaboveelevation 586.5feet (USGS)in the emergency        servicewaterpumphouse       (USAR,Section2.4.10).The emergencyservicewater pumphouseand emergencyservicewater pumpsare designedto provideservicecapacityunderall lakelevelconditions      downto 565.26feet(USGS)levelcaused by the probablemaximumsetdownsuperimposed             on the minimummonthlymeanlake level (USAR,Section2.4.11.6). Two verticalshaftsconveywaterintothe intaketunnel.The intake headsare coveredwith a velocitycap to prevenUminimize        whirlpooling. Withthe invertsof the intakeportsat an averageelevationof 552.65feet (USGS),inflowof sufficientcoolingwateris assured(USAR,Section2.4.11.5).The       corresponding  waterlevelin theemergency    servicewater pumpchamberwouldbe at elevation        562.09feet(USGS).
2.2. Flood-Related    Changesto the LicenseBasis Therewereno changesto theflood-related       licensebasissincethe initiallicenseissuance.
2.3. Changesto the Watershedand LocalArea since Licenselssuance Thewatershed    contributoryto the MajorStreamis determined     to be 7.44squaremilesbasedon the mostcurrentdata available(Reference        PNPP2015c).The watershedcontributory        to the MinorStreamis determined     to be 0.69squaremilesbasedon the mostcurrentdataavailable (ReferencePNPP 2015e).Basedon aerialimagesof the watershed,the changesto the watershedincludecommercialdevelopment             within the watershedarea, which is a small percentage  of the overallwatershedarea.
Thenominaldesignelevation      of sitepowerblockbuildings   (buildings importantto nuclearsafety) are at elevation620.5feet    (USGS)    or higher.Reviewof the     site CorrectiveActionprogram determined theactuatcurrentelevation    of someof the powerblockbuildings    areupto 1.5inches lower(PNPPCondition       Report2009-68678). The changesto the localareasub-watershed        for PNPPincludebuildings      that havebeenaddedor removedand securitybarrierupgradesthat havebeenaddedto thesitesincelicenseissuance.
2.4. GurrentLicensingBasisFloodProtectionand PertinentFloodMitigationFeatures The maximumfloodlevelin the designbasisis belowthe sitefinishedfloorelevationof 620.5 feet (USGS).Therefore,no mitigation    actionswereinitiatedor takenfor floodingat the site.
While performing   this floodingreevaluation,   it was discovered  that the originalanalysisthat supportsthe MinorStream       probable  maximumflood in the      USAR    could not be located.A functionalityassessment    was conducted   and determined   thatthe maximumwaterlevelat the sitebuildings dueto floodingof the MinorStreamdoesnotexceedthe groundfloorelevation             of Unit 1 and Unit 2 site buildingsor affectthe abilityto achieveand maintaincold shutdown conditionsfollowing  a PMP/PMF    event(PNPPCondition      Report2013-05625). Nocompensatory actionsare credited.
PERRYNUCLEARPOWERPLANT                                                                 Page 8 of 35

NTTFRecommendation        2.1 (HazardReevaluations):      Flooding                            Revision 0 FirstEnergyCorporation                                                                February  23,2015
: 3. 

==SUMMARY==
OF FLOODHAZARDREEVALUATION NUREGICR-7046,Design-BasisFtoodEstimationfor SiteCharacterization                   at NuelearPower Plantsin the tJnitedSfafes of America (ReferenceNUREG/CR-7046),                 by referenceto the AmericanNuclearSociety(ANS),statesthat a singleflood-causing               eventis inadequate     as a designbasisfor powerreactorsand recommends               that combinations   should   be evaluated  to determine  the highestfloodwaterelevation      at thesite.ForPNPP,thecombination        that produces the highestfloodwaterelevationat the site safety-related        structuresis the PMF on the Minor Streamwiththe effectsof coincident      windwaveactivity,as providedbelow.
The USARreportselevations        corresponding   to a USGSdatumthatis equivalent         to the NGVD 29 verticaldatum.The recentsitesurvey,UnitedStatesGeological            Survey(USGS)topographic maps,and otherreferencedocumentsreportelevationin the NorthAmericanVerticalDatumof 1988(NAVD88). The Lake Erieelevationsare typicallyreferencedto the International                 Great LakesDatumof 1985(IGLD85).In orderto comparethe                reevaluated  flood  elevations  withthe existingdesignbasiselevationsreportedin the USAR,the final          pertinent   elevations  have been convertedto the NGVD29 datum.The conversionfrom NAVD88 to NGVD29 at PNPPis represented   as: feet NGVD29 = feet NAVD88 + 0.72feet. The conversionfrom IGLD85 to NGVD29 at PNPPis represented         as:feetNGVD29= feetIGLD85 + 0.94feet.
Calculation  50:40.000(ReferencePNPP2015e)definesthe MinorStreammaximumwater surfaceelevationof 623.0feet NGVD29 at PNPPadjacentto the eastsideof the powerblock, whichoccursat the Unit2 TurbineBuilding.        Thiselevationis due to an all-season       PMFevent.
The maximum    watersurfaceelevation      is above  the sitenominal finished  floor elevation of 620.5 feetNGVD29 for a durationof 2 hoursand 15 minutes.
Calculation  50:55.000(Reference     PNPP2015q)definesthe coincident          windwaverunup,The maximum    waverunupelevation      of the PMFcoincident     withwindwaveactivityis determined       by addingthewindwaverunupto thewatersurfacefloodelevation               due to the  PMF. The   maximum waverunupelevation      in the vicinityof the powerblockis 628.3feetNGVD29.Thewaverunup elevationsin the vicinityof the powerblockare abovethe sitenominalfinishedfloorelevationof 620.5feetNGVD29.
Calculation  50:42.OOO   (Reference  PNPP20159)definesthe maximumwatersurfaceelevation resulting fromthe LIPeventadjacentto the entirewestsideof the powerblock.The maximum watersurfaceelevation      due to the LIPeventis 621.2feet NGVD29. The LIP maximumwater surfaceelevation   is abovethe sitenominalfinishedfloorelevation       of 620.5feetNGVD29. Note that becausethe MinorStream        drainage   area  is          small relatively     (less than 1 squaremile),the PMPappliedto the MinorStreamis equalto the LlP.             Therefore the PMF    resultsfor the Minor Streamare equivalent     to the effectsof the LIPon the eastsideof the    power   block.
The methodology     usedin the floodingreevaluation       for PNPPis consistent     with the following standards   andguidancedocuments:
o NRCStandard        ReviewPlan,NUREG-0800,          revisedMarch2007(Reference       NUREG-0800) o NRCOfficeof Standards         Development,    Regulatory                       -
Guides,RG 1.102 "FloodProtection for NuclearPowerPlants",Revision1, datedSeptember            1976(Reference      NRCRG 1.102) and RG 1.S9-"Design      BasisFloodsfor Nuclear       Power  Plants",Revision   2, datedAugust 1977(Reference     NRCRG 1.59)
    . NUREG/CR-7046,          "Design-Basis   FloodEstimationfor Site Characterization         at Nuclear Power Plants in the United States of America,"dated November2011                      (Reference NUREG/CR-7046)
PERRYNUCLEARPOWER PLANT                                                                     Page 9 of 35

NTTFRecommendation       2.1 (HazardReevaluations):     Flooding                           Revision0 FirstEnergyCorporation                                                            February23,2015 o NUREG/CR-6966,        "Tsunami  HazardAssessment     at NuclearPowerPlantSitesin theUnited Statesof America",datedMarch2009(Reference         NUREG/CR-6966)
    . "AmericanNationalStandardfor Determining            DesignBasisFloodingat PowerReactor Sites",datedJuly28, 1992(Reference      ANSI/ANS-2.8-1992)
    . NEI Report12-08,"Overview        of ExternalFloodingReevaluations"      (Reference  NEIAugust 2012) o NRC JLD-ISG      -2012-06,  "Guidance  for Performing   a Tsunami,Surgeor SeicheFlooding HazardAssessment",    Revision 0, datedJanuary4,2013(Reference        JLD-ISG-2012-06) o NRC JLD-lSG-2013-01,         "Guidancefor Assessmentof FloodingHazardsdue to Dam Failure",Revision 0, datedJuly29, 2013(Reference      JLD-lSG-2O13-01)
Thefloodhazardreevaluation,      includinginputsandmethodology,     arebeyondthe currentPNPP designand licensebasis.Consequently,       the analytical resultsprojectbeyondthe capability        of the currentdesignbasis.The followingprovidesthe flood-causing              mechanisms     and their associated  watersurfaceelevations    thatareconsidered   in the PNPPfloodhazardreevaluation:
3.1. Floodingin Streamsand Rivers(ReferencePNPP2015a,PNPP2015b,PNPP2015c, PNPP2015d,PNPP2015e,PNPP2015f,PNPP20{5n,PNPP2015r,and PNPP2015s)
The PMF in riversand streamsadjoiningthe site is determinedby applyingthe probable maximumprecipitation     (PMP)to the drainagebasinin whichthe site is located.Becausethe watersheds   analyzedaresmall,the representative      PMPis pointprecipitation. Thisis identical    to the LlP.Furthermore,   the proximity of the MinorStreamto PNPPcreatesa condition         wherethe MinorStreamfloodingbasedon pointprecipitation          PMPis identical to the LIP analysisfor the MinorStreamandthe adjacentSSCs.
The PMFis basedon a translation      of PMPrainfallin thewatershed    to floodflow.The PMPis a deterministic  estimateof the theoretical  maximumdepthof precipitation      that can occurat a certaintimeof   year for a specifiedareaat a   particulargeographical location.A rainfall-to-runoff transformation  function, as wellas runoffcharacteristics, basedon thetopographic     anddrainage systemnetworkcharacteristics      andwatershedproperties,    are neededto appropriately     develop the PMFhydrograph. The PMFhydrograph      is a timehistoryof the discharge andservesas the inputparameter   for otherhydraulic  modelsthatdevelopthe flowcharacteristics,      including  flood flowandelevation.
The PMFis a functionof the combined      eventsdefinedin NUREG/CR-7046       for floodscausedby precipitation events.
Alternative 1 - Combination   of:
      . Meanmonthlybaseflow o Mediansoilmoisture Antecedent  or subsequent   rain:the lesserof (1) rainfallequalto 40 percentof PMPand (2)a 500-yearrainfall a   TheAll-Season    PMP o   Wavesinducedby Z-yearwindspeedappliedalongthe criticaldirection Alternative 2 - Combination   of:
       . Meanmonthlybaseflow PERRYNUCLEARPOWERPLANT                                                                  P a g e1 0 o f 3 5

NTTF Recommendation     2.1 (HazardReevaluations): Flooding                          Revision     0 FirstEnergyCorporation                                                        February  23,2015
      . Snowmelt   fromthe probable  maximumsnowpack
      . A 1O0-year,  snow-season  rainfall o Wavesinducedby Z-yearwindspeedappliedalongthe criticaldirection Alternative3 - Combination  of:
o Meanmonthlybaseflow
       . Snowmelt    froma 1O0-year  snowpack
       . Snow-season    PMP
       . Wavesinducedby 2-yearwindspeedappliedalongthe criticaldirection 3.1.1. Basisof Inputs:
Theinputsusedin the PMP,snowmelt,     andPMFanalysesarebasedon thefollowing:
All-SeasonPMPAnalysisand Cool-seasonPMPwith SnowmeltAnalysis
          . PNPP,MajorStream,andMinorStreamwatershed           locations;
          . Probable   MaximumPrecipitation  Study for the Stateof Ohio; o Site-specific,all-season PMPpointrainfallshortdurationestimates    determined   using a storm-based   approachin accordance with NOAAHydrometeorological     Reportsand theWorldMeteorological   Organizationapproach;
          . Site-specific, cool-season  PMP pointrainfallestimatesdeterminedusinga storm-based approachin accordancewith NOAA Hydrometeorological          Reportsand the WorldMeteorological   Organizationapproach; o The 100-year,all-seasonpoint rainfallestimatesfrom the NationalOceanicand Atmospheric  Administration (NOAA)Precipitation FrequencyDataServer,andratioof cool-season   to all-seasonrainfalldepthsdeterminedfrom the regionalRainfall Frequency  Atlasof the Midwest; o Dailysnowdepthanddensityby monthfor Ohio,datais downloaded          fromNOAA;and
          . Snowmeltrate (energybudget)equationsand constantsare basedon U.S.Army Corpsof Engineers   (USACE)   Engineering ManualEM-111A-2'1406.
PMFAnalysis-Hydrologic      and HydraulicAnalysis
          . PNPP,MajorStream,andMinorStreamwatershed            locations, areas,boundaries   and configurations; o Precipitation andassociated   snowmelt,as applicable, for the subjectwatershed   area; a Baseflow:Historic   flowratedatacollectedby USGSat gauge04212100       on the Grand River,whichis usedto determinethe baseflow for the MajorStreamand Minor Stream; a Sitetopography    developed fromaerialphotogrammetry; O  Digitalterrainmodel(DTM)developed    fromsitetopography; a  Manning's   roughness  coefficientsare  based on a visual assessmentof aerial photography  andselected  usingstandard applicableengineering  guidance references; and Sitedataforthe raillinebridgecrossing  the MajorStream.
PERRYNUCLEARPOWER PLANT                                                           P a g e1 1 o f 3 5

NTTFRecommendation      2.1 (HazardReevaluations):   Flooding                            Revision 0 FirstEnergyCorporation                                                           February  23,2015 3.1.2. ComputerSofhryare      Programs PMPand Snowmeltanalysis
         . ArcGlSDesktop10.1 o MicrosoftExcel o SPAS9.5 PMFanalysis
         . AutoCADCivil3D 2012
         . ArcGlSDesktop10.0
         . ArcGlSDesktop10.1
         . HEC-HMS    3.5
         . HEC-RAS    4.1
         . HEC-GeoRAS     10.1 o    MicrosoftExcel 3.1.3. Methodology Thesite-specific  PMPanalysisincluded     thefollowingsteps:
o An extensivestormsearchto identifystormswhichcouldbe usedfor PMPstudiesin the region.
         . Largestprecipitation      eventswhichwere determinedto be transpositionable       to the PNPPsitewerethenmaximized         in-placeandtranspositioned  to the site.
Site-Specific,  All-SeasonPMP All the stormsevaluated    in the previousPMPstudiesin the region,andconsidered      to be transpositionable  to the PNPPsitewereevaluated.      Thisresulted in 20  events thatwere evaluated   to determine  the shortduration1-hourdepthfor the site-specific,    all-season PMP.Ten of thesestormswerepreviously         analyzedin Hydrometeorological     ReportNo.
33 andHydrometeorological       ReportNo.51 by the National  WeatherService(NWS)and the USACE.The remaining1O          were analyzed for the Probable  MaximumPrecipitation Studyfor the Stateof Ohio.
Eachstormis thenmaximized         by an in-placemaximization factorto represent   whatthe storm  would  havelooked    like had the atmospheric conditionsand  moisture   availablefor rainfallproductionbeenat maximumlevelswhen           the stormoccurred   versus  what was actuallyobserved. The in-placemaximized    valuesfor eachstormare thenadjustedto transposethe storm from its originallocationto the PNPP site. The transposition calculation  adjustsfor differences   in availablemoistureat the site versusthe original stormlocation.The ratiosto determinesub-hourly         increments in Hydrometeorological ReportNo. 52, are appliedto the          resultingsite-specific,1-hour   PMP estimateto determine   5-, 15-,and3O-minute    durationestimates.
Site-Specific,  Cool-Season      PMP A site-specific, cool-season    depth-area-durationrelationshipis developed   for durations from 1 to 72 hoursand areasizesfrom 1 to 20,000squaremiles.In addition,hourly temperature,   dewpoint,andwindspeedtimeseriesaremaximized           for cool-season  PMP for input  parameters  of associated  snowmelt. Ten  extreme rainfallstorms  that occurred from Octoberto May withinthe GreatLakesregionare identified.            Althoughthe cool-seasonmonthsareOctoberthroughAprit,stormsduringthe month Maythatrepresent of PERRYNUCLEAR       POWERPLANT                                                        Page 12 of 35

NTTF Recommendation      2.1 (HazardReevaluations):      Flooding                                Revision0 FirstEnergyCorporation                                                                 February    23,2015 cool-season    characteristics  are includedin the analysisfor determining       the site-specific, cool-season    PMP SPASsoftwareanalysisis completed          for threestormsthatwerenot analyzedpreviously by the NWS or USACE,or occurredafter the publicationof the hydrometeorological documents. The moisturecontentof eachstormis maximized              to providethe upperlimit rainfallestimation   for eachstormat the location    where   it occurred.Themaximized       storms are then transpositioned       from the originalstorm locationto           PNPP     to  the extent supportableby similarityof topographicand meteorological                   conditions.Maximum precipitation   values,adjustedfor in-placemaximization           and transposition    factors,are enveloped    to definethe cool-season    PMP.
The PMFanalysisincludes        thefollowing steps:
         . Delineatewatershedand sub-watersheds             and calculatesub-watershed          areasfor inputintothe USACEHEC-HMS            rainfall-runoff hydrologic   computer   model.
         . Determine      rainfall.
         . EstimateHEC-HMSrainfall-runoff             model input parameters:NationalResources Conservation    Service(NRCS)unithydrograph          method.
o Adjustunithydrograph         to accountfor the effectsof nonlinear      basinresponse.
         . PerformPMFsimulation          withPMP    input using  HEC-HMS       model  withno precipitation losses.
o Estimatewater surfaceelevationusing HEC-RASunsteady-state                       modelby using runoffhydrograph      fromthe HEC-HMS      modelas an input.
WatershedDelineation Forthe purposesof the hydrologic       modelingeffort,the MajorStreamis evaluatedusing onewatershed. TheMinorStreamwatershedis subdivided             intothree(3)sub-watersheds (theMinorStreamsouthof the site,the MinorStreamand site areacontributing                    to the MinorStreamat the lateralswalebetweenthe two coolingtowers,and the unnamed tributaryeastof the site)basedon the topography          of the site.
Rainfalland Snowmelt Eachatternative   containsrainfalldefinedeitherbytheall-season           PMP(Alternative    1),the 1O0-year, cool-season      rainfall(Alternative 2), or the cool-season     PMP    (Alternative  3).
Eachrainfalleventis considered      to be a72-hourdurationevent.Notethatan antecedent rainfalloccurspriorto the all-season     PMP.Becauseof the smalldrainageareasof the MajorStreamand MinorStreamand the 72-hourdry periodbetweenthe antecedent stormand the PMPevent,the streamsreturnto baseflowconditions                    priorto the PMP event.Therefore,the antecedent        stormis determined      to  have no  influence   on the PMP storm.Theall-season       eventincorporates    no rainfallrunofflosses.
Snowmelt   is includedin thetwocoolseasonalternatives.          Alternative 2 includes  snowmelt fromthe   probable    maximumsnowpack.        Alternative  3  includes   snowmelt   from  the 100-yearsnowpack.      Forrain-on-snow    conditions  dew   point   temperature  and  wind   speed  are obtained fromthesite-specific     PMPanalysis. Thebasinwindcoefficient        is conservatively assumedto maximize        snowmelt.
Thesnowpackis assumedto be at its maximumat the onsetof rainfalleventsandcover theentirewatershed.      Soilis assumed   to be frozenwithno precipitation      lossesduringthe cool-season   monthsof OctoberthroughApril.Forthe probable             maximumsnowpack,        the snowpack   depthis assumed      to providecontinuous    snowmelt    for theentiredurationof the coincident  rainfallevent.
PERRYNUCLEAR       POWERPLANT                                                                Page13of35

NTTFRecommendation      2.1 (HazardReevaluations):       Flooding                             Revision 0 FirstEnergyCorporation                                                               February    23,2015 AlternativeI -All-Season PMP The all-season   PMPis determined       by usingthe site-specific  PMPestimates       definedby the PMPstudyfor the Stateof Ohio(Reference            ODNR2013)for durations        from6to72 hours.The PNPPsite-specific         analysisdefinesthe PMPestimates        for t hourand sub-hourlyincrements. lntermediate    S-minuteincremental    PMPdepthsare determined         for pointprecipitation  (1 squaremile).
Thetemporaldistribution      of the PMPis arrangedin accordance         with recommendations in HMR-52,whereinindividual         rainfallincrements  decreaseprogressively     to eitherside of the greatestrainfallincrement. Varioustemporaldistributions   for eachrainfallscenario arethenevaluated     to furthermaximizethe runoff.Front,onethird,center,twothirds,and end-loading  temporaldistributions     are considered   in an effortto capturethe distribution thatmaximizes    runoff.
Alternative2 - ProbableMaximumSnowpackand 100-YearGool-Season                          Rainfall
         \l/hilesnowpackcan be determined          directlyfromthe snowdepth,adequatedata is not available to extrapolate   any historical  observations  up to the magnitude    of the probable maximumevent.To maximize           snowmelt   contribution, the probable  maximum     snowpack is conservatively assumednotto depleteduringthe durationof the coincident             rainfall.
The 1O0-year,   cool-season    rainfallis determined  forthe PNPPlocationanda durationof 72-hoursusingprecipitation       frequencyestimatesdefinedby NOAAAtlas 14 guidance and applyingregionalseasonalguidance.NOAAAtlas 14 providesall-seasonpoint precipitation rainfallestimatesvia the NOAAprecipitation         frequencydata server.The NOAAAtlas14 valuesare adjustedto reflectcool-season             rainfallratherthanall-season rainfall.
The 100-year,cool-seasonrainfallis equivalentfor all the cool-seasonmonths.
Furthermore,   the maximizeddew point temperatureand wind speed time series determined   bysite-specific   analysisis applicable  to allcool-season   months.To maximize snowmeltat eachtimestep,the dew           point temperature  and wind  speed   are reordered  to matchthe 72-hourtemporaldistributions         of the rainfall.
Alternative3 - 1O0-Year      Snowpackand Cool-SeasonPMP A 10O-year   snowdepthis calculated        by performing   a statisticalanalysisbasedon the historicaldataobtainedfromthe NOAANationalClimaticDataCenterdailysnowdepth records.A Fisher-Tippett      Type l (FT-l)distribution   frequencyanalysisis performedto determine  the maximumsnowdepth           with an  annual exceedance    probability of 1 percent (i.e. 100-yearsnow depth)for each monthfrom OctoberthroughApril. The FT-l distributionis applicablefor long-termstatisticalanalysesand specifically           for extreme valuecalculations. The maximumsnowpackbulk densityis appliedto determinethe available snowwaterequivalent.       Themaximum100-year        snowpack    occursin Marchand is combined  withthesite-specific,    cool-season   PMP.To maximize      snowmelt   at eachtime step,the dew    point  temperatureand wind speed         are reordered   to match   the 72-hour temporaldistributions    of the rainfall.
HydrologicModel(HEC-HMS)
ThePMFis thefloodresulting        fromthe72-hour    duration all-season  PMPor a combination of cool-season  rainfallandsnowmelt.      Thetemporaldistribution    of the PMPis determined in accordance    with the recommendations         in HMR-52,whereinindividualincrements decrease   progressively  to eithersideof the     greatest increment.Front,one-third,center, two-thirds, and end-loading     temporaldistributions   are consideredin an effortto capture PERRYNUCLEAR      POWERPLANT                                                              Page14of 35

NTTFRecommendation     2.1 (HazardReevaluations):    Flooding                           Revision0 FirstEnergyCorporation                                                          February  23,2015 the distributionthatmaximizes   runoff.Becauseof the smalldrainageareasof the Major StreamandMinorStreamandthe 72-hourdry periodbetweenthe antecedent               stormand the PMPevent,the antecedent      stormis determined     to haveno  influence  on the PMP storm.
USACEHEC-HMShydrologicsoftwareis used to convertrainfallto runoff.A rainfall hyetographis appliedto the MajorStreamwatershedand each sub-watershed                of the MinorStreamandtransformed       to runoffusingunithydrograph    methodology. Generally, a unit hydrograph   is developedusinghistoricaldata obtainedfrom variousrain and streamgaugesin the watershed.      The MajorStreamand MinorStreamwatersheds              are ungauged. Thus,no historical   observations  are availableto use as a basisto createa unit hydrograph. Therefore,a syntheticunit hydrographis developed.NRCS unit hydrographmethodology     is usedfor rainfall-to-runofftransformation.
ANSI/ANS-2.8-1992    suggests  thatbaseflowshouldbe basedon meanmonthlyflow.As meanmonthlyflowis notavailable      for the MajorStreamor MinorStream,the baseflow is approximated  basedon the meanmonthlyflowin an adjacentwatershed.           The USGS gaugestationon the GrandRivernearPainesville,      OH is used.TheGrand      River  is in the samehydrologic    unitas the MajorStreamand MinorStreamand hassimilarwatershed characteristics.Therefore,it is an acceptable  approachto usethe baseflow information for the GrandRiveras the basisfor estimationof the baseflow for MajorStreamand MinorStream.
To conservatively  maximizerunoff,no precipitation   lossesare incorporated    intothe all-seasonPMFalternative      analysis.Additionally,                lossesare incorporated no precipitation intothe cool-season   PMFalternatives  dueto the assumption   thatthe groundis frozen.
The unit hydrographs   for the MajorStreamwatershedand eachsub-watershed             of the MinorStreamare modifiedto accountfor the effectsof nonlinearbasinresponsein accordance  with NUREG/CR-7046.      The peakof eachunithydrograph        is increased    by one-fifthand the time-to-peakis reducedby one-third.         The  remaining    hydrograph ordinatesare adjustedto preservethe runoffvolumeto a unit depthoverthe drainage area.
HydraulicModel(HEC-RAS)
The unsteadyflowsimulation     modulewithinthe USACEHEC-RASsoftwareis usedto transformthe resultingflow hydrographs      from the controllingalternativeinto a water surface elevationhydrographunder unsteadyflow conditions.For referenceand comparison,  allthreealternatives areevaluated   withthe HEC-RASmodel.
Channelandfloodplain    geometry  for the MajorStreamandthe MinorStreamis modeled by developing  crosssectionsof the streams.The crosssectionsare placedat locatlons that definegeometriccharacteristics    of the streamand overbanks.Crosssectionsare also placed at representative locations wherechangesoccurin discharge,      slope,shape, and roughness,    as well as at hydraulicand inlinestructures    (e.9., bridges  culverts).
Streambanks,blockedobstructions,      andineffective flowareasare also   incorporated   into the HEC-RASmodel.
Threecrossingsare incorporated     intothe MajorStreammodel.The plantaccessroad includesa culvertand is modeledusingtopographic         surveydataand USARdata.The upstream  raillinebridgeis modeledusingtopographic       surveydataandsiterecords.      The upstreamsecondaryaccessroadis includedas an inlinestructureand all flow overtops the road.
PERRYNUCLEAR      POWERPLANT                                                         Page15of 35

NTTF Recommendation       2.1 (HazardReevaluations):      Flooding                             Revision0 FirstEnergyCorporation                                                                 February23,2015 One crossingis incorporated        intothe MinorStreammodel.The downstream            Lockwood Roadcrossingis modeledas an inline          structure and  all flowovertops the  road.
The PMF flow hydrographs         obtainedfrom the time-seriesoutflowresultsof the HEC-HMSmodelsareenteredintothe HEC-RAS                models. A bounding  waterlevelin LakeErie is usedas a downstream         boundarycondition    for the HEC-RAS    softwareprogram.The HEC-RAS    modelis evaluated      fortheall-season   PMF   (Alternative 1)andthecool-season PMF(Alternative     2 andAlternative    3).
3.1.4. Results MajorStream The MajorStreamis not directlyadjacentto PNPPsafety-related               structures.However, overtopping   at the raillinebridgestructureresultsin overflowfromthe MajorStreamthat contributes  to floodingeffectsin the MinorStreamandthe LIParea.
The Alternative    1 PMF is the controlling     combination   and is a resultof the all-season PMP,Theone-third,        center,andtwo-thirds    temporaldistributions  produceidentical  peak resultsandthemaximumwaterlevels.Themaximumwatersurfaceelevation                     overtopping the raitlinebridgestructure     is 630.9feetNGVD29,witha maximum           flowof 30,100cfsat the bridge.The resultingmaximumwaterlevelsfor the MajorStreamare not adjacentto the powerblock.
Overtopping    of the rail line causesbackwaterto accumulateand flow towardthe site throughtwo accesspointsof the secondaryaccessroad.The peakflowthroughthe two accesspointsis74cfs.Thisflowis incorporated          intothe LIPareaanalysis     by combination withrainfallrunofffor the areadirectlysouthof the plant.
Backwateralsooverflowsthe secondaryaccessroadfurtherto the east.The peakflow intothe MinorStreamwatershedis 1754cfs. Thisflow is incorporated                  intothe Minor Streamanalysisby application        directlyto the upstream  crosssectionof theMinorStream hydraulic  model.
Alternative 2 doesnot overtopthe raillinebridgestructure           and no overflowto the Minor Streamor LIP areaoccurs.The one-third,center,and twothirdstemporaldistributions produceidenticalpeak resultsand the maximumwater levels.The maxlmumwater surfaceelevation    at the raillinebridgestructure    is 621.1feetNGVD29 witha maximum flowof 9,500cfsat the bridge.
Alternative 3 doesnot overtopthe rail linebridgestructureand no overflowto the Minor Streamor LIP areaoccurs.The one-third,            center,and two-thirds  temporaldistributions produceidenticalpeak resultsand the maximumwater levels.The maximumwater surfaceelevation     at the raillinebridgestructure   is 623.1feetNGVD29 witha maximum flowof 14,900cfsat the bridge.
The all-season    PMF is determined      to be the controlling    PMF scenario.An additional combinedeffectanalysis,includingthe            effectsof  wind   wave activity,is performedas discussed   in Section3.7.The contribution         to LIP flooding incorporated is                into the analysis  discussed     in Section3.8.
MinorStream Overtopping    flowfromthe MajorStreamwatershedis addedto the HEC-RASmodeling for the Alternative   1 PMF.Overtopping      flowfromthe MajorStreamwatersheddoesnot occurfor Alternative     2 or Alternative3.
PERRYNUCLEAR        POWERPLANT                                                              Page16of 35

NTTFRecommendation    2.1 (HazardReevaluations):  Flooding                          Revision  0 FirstEnergyCorporation                                                       February  23,2015 The Alternative1 PMF is the controlling  combination and is a resultof the all-season PMP.Theone-third,   center,andtwo-thirds  temporaldistributions produceidentical  peak resultsand the maximumwaterlevels.The      maximum   water surface  elevationoccurs  at the Unit2 TurbineBuildingand is 623.0feetNGVD29. The maximum          flowovertopping LockwoodRoaddownstream      is 5,300cfs.Alternative1 peakfloodingoverflows   the Minor Streamchannelbanksandcontributes     to LIPfloodingonthewestsideofthepowerblock.
For Alternative2, the one-third,center,and two-thirdstemporaldistributions     produce identicalpeak resultsand the maximumwater levels.The maximumwater surface elevationoccursat the Unit2 TurbineBuilding  andis 620.6feetNGVD29.Themaximum flow overtopping LockwoodRoaddownstream       is 1,000cfs.Alternative2 peakflooding overflowsthe MinorStreamchannelbanksand contributes        to LIP floodingon the west sideof the power block.
For Alternative3, the one-third, center,and two-thirdstemporaldistributions    produce identicalpeak resultsand the maximumwater levels.The maximumwater surface elevationoccursat the Unit2 TurbineBuilding  andis 621.1feetNGVD29.Themaximum flow overtopping LockwoodRoaddownstream       is 1,600cfs.Alternative3 peakflooding overflows the MinorStreamchannelbanksand contributes       to LIPfloodingon the west sideof the powerblock.
The all-season PMF(Alternative1) is determined    to be the controlling PMFscenario.
The maximumwatersurfaceelevationsat eachsafety-related        structureadjacentto the MinorStreamfloodingand the durationof floodingabovethe nominalfinishedfloor elevationof 620.5feetNGVD29 areprovidedin Table1. An additional       combined   effect analysisis performed as discussed  in Section3.7.The contribution   to LIP floodingis incorporated intothe analysisdiscussed    in Section3.8.
TableI - MinorStreamFloodingElevationsand Durationsat PNPP MaximumWater SurfaceElevation       Flood Duration above Structure              (feetNGVD29)         620.5 feet (NGVD 29)
Unit2 TurbineBuilding             623.0              2 hours15 minutes Building Unit2 Auxiliary                    622.9             2 hours10 minutes Unit2 ReactorBuilding              622.3              t hour10 minutes lntermediateBuilding               622.2              t hour10 minutes Unit1 ReactorBuilding              622.2              t hour10 minutes Unit1 Auxiliary Building             622.2              t hour10 minutes Unit1 TurbineBuilding              621.1                 40 minutes PERRYNUCLEARPOWERPLANT                                                            Page17of 35

NTTFRecommendation        2.1 (HazardReevaluations):    Flooding                          Revision 0 FirstEnergyCorporation                                                             February 23,2015 3.2. DamAssessment(ReferencePNPP2015h) 3.2.1. Basisof Inputs Inputsusedfor the damassessment        evaluation include:
o PNPP,MajorStream,andMinorStreamwatershed                 locations.
           . USGStopographic       quadrangle   maps.
o The USACENationalInventoryof Dams(NlD) databaseis usedto identifyany watershed  dams.
3.2.2. ComputerSoftwarePrograms
           . None 3.2.3. Methodology ThePNPPMajorStreamandMinorStreamwatershed                 locations areapproximated using USGS topographic       quadrangle   maps. The  USACE      NID  database  is reviewed  to determine   thatno damsarelocatedin the MajorStream         or Minor Stream watersheds.
3.2.4. Results No damsarelocatedin the combined        watershed   of the MajorStreamandMinorStream.
Therefore,  damfailureis notapplicable.
3.3. lce-lnduced     Flooding(Reference     PNPP2015i)
As identified  by NUREG/CR-7046,     icejamsandicedamscanformin riversandstreamsadjacent to a site,and mayleadto floodingby two mechanisms:
       . Collapse   of an icejam or an icedamupstream     of the sitecanresultin a dambreach-like floodwavethatmaypropagate        to the site;and o An icejam or an ice dam downstream          of a site may impoundwaterupstreamof itself, thuscausinga floodvia backwater      effects.
3.3.1. Basisof Inputs
           . USACEicejam database.
o Sitetopography.
           . Bridge geometry(upstreamand downstreamof PNPP)                                using site topography   andsiterecords.
3.3.2. ComputerSoftwarePrograms
           . MicrosoftExcel 3.3.3. Methodology PerNUREG/CR-7046,        ice-induced floodingis assessed    by reviewingthe USACEicejam databaseto determine    the mostseverehistorical   eventsthathaveoccurred.No historical recordsareavailable    for the MajorStreamor the MinorStream.Thenonexistence        of ice jam recordsis explainedby the absenceof stream monitoringstationson the two streams.Basedon icejam occurrences         recordedfor riverswithinadjacentwatersheds, it is determined  thaticejam eventsarepossible.
PERRYNUCLEAR         POWERPLANT                                                         Page18of 35

NTTF Recommendation    2.1 (HazardReevaluations):     Flooding                               Revision0 FirstEnergyCorporation                                                               February23,2015 The maximumice jam is determined        by selectingthe historiceventthat producedthe maximumflood stage relativeto the normalwater surfaceelevation              n a t that location.
Regardless  of the specificconditions that produced    the historic flood  stage  at a specific location,thefullheightis conservatively   assumedto represent       the ice jam.
icejam dataforthe adjacentwatersheds Historical                                           for the GrandRiverandtheAshtabula Riverare considered. Althoughno recordsare available      for the actualheightof the ice jams,the maximumrecordedstageis usedto representthe ice jam. The ice jam is transposed  to the siteandcompared     withotherfloodingcausingmechanisms.
3.3.4. Results The maximumreportedicejam stagein the regionalvicinityof PNPPis estimated                 to be 18feet.Forthe MinorStream,no significant     upstream    crossings  or structures  are present that couldfacilitatesignificantice jam formation.The only upstreamaccessroadis an unimprovedroad with a low profileand a small drainagestructure.The elevation characteristics  of the areaat thatdrainagestructureindicatein the unlikelyeventan ice jam did occur,it wouldbe limitedto lessthan2 feetin height.Furthermore,             any icejam and subsequent    failurewouldonlyreleasea flow rateat the maximumcapacityof the smalldrainagestructure. By qualitative comparison,     the PMFanalysisincludesrainfall runoffcontribution  fromthe entiredrainagearearesultingin a peakflowratemagnitudes greaterthanthe capacityof a smalldrainagestructure.        Any upstreamicejam collapseis bounded  by thePMFanalysis.
The only downstreamlocationon the MinorStreamconduciveto an ice jam is at LockwoodRoad.The assumedtransposition           of the maximumicejam wouldproducea maximumwatersurfaceelevationof 608.7feetNGVD29 (608feetNAVD88).Assuming theculvertat LockwoodRoadis completely        blocked,anycoincident      flowwouldeventually overtop LockwoodRoad. The PMF analysisfor Minor Stream assumesthe Lockwood Road culvert is completely blocked and the PMF overtops the road. Therefore,by qualitativecomparison     with the PMF analysis,any downstreamice jam flooding is bounded  by thePMFanalysis.
Forthe MajorStream,the upstream      raillinebridgehasa clearheightof greaterthan20 feetfromnaturalgradeto the bottomof the lowchord.Theassumedtransposition                 of the maximumestimated       18 feeticejam wouldallownormalflowsovertopping            the icejam  to flowthroughtheremaining      bridgeopeningbelowthe lowchord.ThePMFanalysis the          for MajorStreamresultsin overtopping       of the rail line bridge.Any ice jam failureat this locationwouldbe transposed      downstream  to the plantaccessroad.
The accessroad includesa largeellipticalculvert35'-11"by 23'-5".Basedon site topography  the clearheightis approximately      18 feet abovethe normalwatersurface elevition.Assumedtransposition      of the maximumestimated18 feet ice jam would producea maximum       watersurfaceelevation   belowthe plantaccessroad.Assuming            the culvertat the plant access road is completelyblocked,           any   coincident   flow  would eventually overtopthe plantaccessroad.The PMFanalysisfor MajorStreamresultsin overtopping of the plantaccessroad.Therefore,      by qualitative  comparison    withthe PMF analysis,anyicejam floodingis boundedby the PMFanalysis Thedownstream      sedimentcontrolstructureis the onlyotherlocationpossiblyconducive to an ice jam. The assumedtransposition       of the maximumice jam wouldproducea maximumwatersurfaceelevationof 604.7feetNGVD29 (604feetNAVD88).Theresults of the PMFanalyses     for the MajorStreamexceedthe estimated        icejam elevation.
PERRYNUCLEARPOWERP1ANT                                                                    Page19of 35

NTTFRecommendation      2.1 (HazardReevaluations):     Flooding                          Revision 0 FirstEnergyCorporation                                                           February23,2015 lce-inducedfloodingat PNPP is boundedby the PMF analyses,and no further considerationis required.
3.4. GhannelMigrationor Diversion(ReferencePNPP2015i)
NUREG/CR-7046     indicates historicalrecordsand hydrogeomorphological      datashouldbe used to determine  whetheran adjacent channel,   stream,or riverhasexhibited  thetendency   to migrate towardsthe site.
3.4.1. Basisof Inputs
           . OhioDepartment   of NaturalResources             geologymap surficial
           . USGStopographic   quadrangle    maps,including   aerialimages 3.4.2. GomputerSoftwarePrograms o None 3.4.3. Methodology Surficialgeologyalongwith historicand currenttopographic          quadranglemaps that includeaerialimagesare reviewed     to examinethe condition   andalignment  of riversand streamsovertime.
3.4.4. Results The surficialgeologymap indicatesthe area in the immediatevicinityof PNPP is characterized by layersof sand,silt and clay,and till or clayeyto silty till over shale bedrock.Thischaracterization   represents   the entirewatershedof the MinorStreamand the majorityof the MajorStream.The upstreamportionof MajorStreamis characterized by additionalareasof sandandgravelor clayeyto siltytill overshalebedrock.        Alluvium or organicmaterial, whichare moresusceptible      to erosion,are not presentin the Major Streamor the MinorStreamwatersheds.
Topographic  mapsfor the yearsof 1905(Reprinted       1943),1960(Revised1992),1994, and 2010 are reviewedto assesshistoricchannelmigration.          The MinorStreamwas rerouted as part of the plant construction.These modificationshave remained unchanged. Thetopographic   and aerialimagesprovideno evidenceof oxbows,braided streams,or alluvialfansthatcouldindicatea potential     for channelmigration of the Major Streamor the MinorStream.
Thestreamsin thevicinityof PNPPdo notexhibitcharacteristics       of channelmigration.
3.5. StormSurge(ReferencePNPP20151,             PNPP2015k,PNPP20151,        PNPP20{5o' and PNPP20{5p)
ProbableMaximumStormSurse(PMSSl In accordance  with JLD-ISG-2012-06,    all coastalnuclearpowerplantsitesand nuclearpower plantsitesadjacentto coolingpondsor reservoirssubjectto potentialhurricanes,         windstorms and squatllinesmustconsiderthe potential       for inundation fromstormsurge    and waves. JLD-ISG-2012-06   alsosuggests  thatfor the stormsurgehazardassessment,                 storm historical     events in the regionshouldbe augmented    by a synthetic   stormparameterized  to accountfor conditions moreseverethanthoseinthehistorical      recordsandconsidered      reasonablypossible onthebasis of technical reasoning.
PERRYNUCLEAR       POWERPLANT                                                         Page 20 of 35

NTTFRecommendation    2.1 (HazardReevaluations): Flooding                           Revision0 FirstEnergyGorporation                                                       February23,2015 3.5.1. Basisof Inputs Theinputsusedin PMSSanalysisarebasedon thefollowing:
         .            windand pressurefielddatafromNOAAfor the GreatLakeRegion Historical o   Probablemaximum    windstorm (PMWS)
         . LakeEriebathymetry   fromthe NOAAgeophysical    database
         . Supporting GISdata 3.5.2. ComputerSoftwarePrograms
         . ArcMap10.1
         . Deft3D softwaresuite (Delft3D-FLOWDelft3D-WAVE,Delft3D-RGFGRID,                and Delft3D-QUICKIN)
         . lGLD85HeightConversion    Tool
         . R Computer  Language   2.15.1
         . MicrosoftExcel 3.5.3. Methodology Several physicalprocessescontributeto the generationof a storm surge. The contributionof windto a stormsurgeis oftencalledwind setup.\Mnd blowingoverthe watercausesa shearstressthatis exertedon the surfaceof the water,pushingwaterin thedirectionof thewind.Atmospheric   pressure gradients areanotherforcingmechanism that contributesto changesin water level, as water is forcedfrom regionsof high atmospheric  pressuretowardregionsof low atmospheric    pressure.
Thefollowing  describesthe methodologies  usedin the PMSScalculation:
Developmentof the PMWS The PMWSstorm-basedapproachis specificto the characteristics          of the site. Past extremeeventsin a   region areanalyzed and  considered transpositionable. As partof the PMWS,differentstormtypes(suchas synoptic,squall     line, and hybrid)that impactedthe GreatLakesregionareconsidered    in orderto determine thestormevent   thatwillgenerate themaximum    surgeandseiche.Eachstorm'sinputparameters      are quantifiedandplotted basedon the locationof low/highpressurecenters,concurrent    wind/pressure  fields,and howtheyevolvethroughtimeandspace.
Mostof the synopticstormsoccurin association   with deepareasof low pressurewhich movethroughthe regionfrom southwestto northeast.The generalsynopticpatternis one in whichthe deep area of low pressureresultsin a very strongpressuregradient forcebetweenits low pressurecenterand a corresponding      regionof higherpressureto the northor west.The largerthe gradientbetweenthe two    systems overa givendistance is,the strongerthe resultingwinds.
Squallline (or derecho)events createa widespreadstraight-linewindstormthat is associatedwith a fast-movingband of severe thunderstorms.         These winds have produced  someof the highestinstantaneous  gustson record,but  lastforonlya shorttime (lessthan30 minutes)at a givenlocation.The shortdurationof theseevents,as they quicklytraversea givenlocation,meanstheywill not controlthe PMSS.Further,these eventsdo not occurwithindeep low pressuresystemsor remnanttropicalsystems' Therefore, theirwindand pressuredataare not combinedwiththe otherstormtypesin thisanalysis,as thiswouldresultin a PMWSthatis not physically    possible.
PERRYNUCLEARPOWERP].ANT                                                           Page21 of 35

NTTFRecommendation     2.1 (HazardReevaluations):      Flooding                         Revision   0 FirstEnergyCorporation                                                          February  23,2015 Althoughdeep tow pressuresystemsoften producethe longestdurationlarge-scale winds,otherstormtypesalsoproducestrongwindsoverthe region.In rarecases,land-fallingtropicalsystemsalongtheGulfCoastor AtlanticSeaboard         moveinlandacrossthe Appalachians   or up the Mississippi    and Ohio Rivervalleys.By the time thesestorms reachthe GreatLakesregion,they are no longertropicalsystems,but insteadhave transitionedintoextra-tropical   cyclones.Theirgeneralcirculation  andcenterof deeplow pressurepersists.Muchlikethe deeplowpressurescenariopreviously           discussed, strong and  persistent winds   can result. The remnants  of HurricaneHazel  (October  1954)  and HurricaneSandy      (October  2012)areclassicexamples      of this storm  type.This  storm scenarioprovidedsomeof the strongestwindsfromthe northwestthroughthe northeast directions overLakeErie(withdurations       of 12 hoursor more).
Delft3DGalibration The Delft3Dhydrodynamic       modelis set up usingthe Delft3Dsoftwaresuite.The wave setupcontribution   to the total stormsurgevaluesare modeledby couplingthe Delft3D-WAVEandDelft3D-FLOW          surgemodels.Thegeneralapproach       to stormsurgemodeling usingcoupledDelft3D-FLOW         andDelft3D-WAVE     modelsconsistsof thefollowingsteps:
o Developing     the bathymetric   datasetandmodelgridmeshfor the lakesystem; o Assembling      inputfilesfor atmospheric   forcing(windandpressure   fields);
         . Assembling      inputfilesfor initialwaterlevel,boundary  conditions,andthe physical andnumerical    parameters    of the model; Assemblingmeasuredwater levelsand wave data for modelcalibrationand verification; Testingand refiningthe initialmodelsetup; I   Validating the modelfor historical   extremestormevents;and o Assessingmodelsensitivity        to variousfactorsandadjustable  parameters   suchas bottomfrictionandwinddragcoefficient.
The Delft3Dmodel is calibratedbased on historicaldata obtainedfrom NOAA meteorological  andwaterlevelrecording      stationslocatedin the LakeErieregion.
Reviewof historicaldatashowsthatvariouspartsof LakeErieresponddifferently           to any one particularstorm.The stormthat producesextremewaterlevelsin one            part of Lake Eriemightnot,and probablydoesnot,produceextremelevelsin otherparts.Therefore the numberof calibration     and validationstormsselected,to assessmodelprediction accuracy,coveredall     parts of the lakeshoreline.
Calibration and verification  of the coupledDelft3D-FLOW     and Delft3D-WAVE    modelsis performedby a timeseriescomparison         of measuredandpredicted/modeled    stormsurge valuesat differentwater levelrecordingstationson Lake Erie.A similartime series comparison   is alsoperformed    for waveheights.
The Delft3Dmodelsare calibratedusingextremehistoricwind and pressuredatafrom multiplemeteorological    andwaterlevelrecording     stations.Calibrationandverification  of the coupled Delft3D-FLOWand Delft3D-WAVE                 models   demonstrates    that  the hydrodynamic    modelis capableof computing       the stormsurgeandseichedynamics        for LakeErie,as well as the significant      wave heightsand periodsat PNPPfrom        PMWS events.
PERRYNUCLEARPOWERPLANT                                                               Page22 ot 35

NTTF Recommendation      2.1 (HazardReevaluations):      Flooding                             Revision0 First EnergyCorporation                                                               February23,2015 PMSS The calibratedDelft3Dmodelis usedto determinethe PMSS.The historicwind and pressurefielddata is replacedwith candidatePMWSevents,and the modelis run to determine the criticalPMWS.
JLD-lSG-2012-06    andANSI/ANS2.8-1992requiretheantecedent             (pre-storm)  waterlevel equalto the 1O0-year     maximumrecordedwaterlevelto be appliedas the initialstorm surgemodelstillwaterlevel.The 1O0-year        waterlevelof 575.6feetNGVD29 (574.6feet IGLD85) is usedas      the initialcondition/antecedent   waterlevelin all the Delft3D-FLOW models.Sincethe    probable   minimumlowwaterlevelat PNPPcouldoccurat a timewhen the monthlymeanlakelevelis at the long-termmeanlow probablelevel,the antecedent waterlevelfor lowwaterevaluation      is setto the long-term lowprobablelevelat LakeErie, whichis equalto 568.9feetNAVD29 (568feet IGLD85).
Varioustopographic    featuresaffectthe stormsurgepropagation        towardsPNPP.Thesite is locatedon the bluffsadjacentto the shoresof LakeErie.Thebluffsat the sitearemore than40 feetabovethe 100-yearwaterlevelof the lake.
MaximumHistoricaland 2S-yearStormSurge The historical maximumstormsurgeis the largestof the determined              yearlymaximum stormsurgeheights.The historicat        maximumstormsurge        height is used   in combined floodingscenarios   as discussed   in Section3.7.
Storm surgesare calculatedfrom monthlydata as the differencebetweenmonthly maximumandmonthlymeanbasedon guidanceprovidedby USACE.TheLogPearson Typelll distribution is thecommonly     accepted  frequency  procedure   for annualmaximum waterlevels.A frequency      analysison theyearlymaximumstormsurgeheightsobtained from the Fairportand Erie stationsis performedusing a Log Pearsonlll statistical analysis.The 25-yearstormsurgeheightis usedin combined            floodingscenarios.
3.5.4. Results Simulations of all the candidatePMWSeventsshowedthat the criticalPMWSeventis the transpositioned   September    1989windstormeventmaximized           overthe PNPPsite.
Thisstormis the mostintenseof all the PMWSeventswith a maximumwind speedof 106 miles/hour   and is alignedalongthe north-south         direction.The maximumPMSS resultingfromthis PMWSeventproduceda maximumwatersurfaceelevationof 582.6 feet NGVD29, which is well belowthe site. Wave runupeffectsare evaluatedwith combined  floodingscenarios     as discussed   in Section3.7.
Surge,Seiche,and Resonance Resultsshowthat the levelof the rise due to a seicheis significantly             less than the calculated surgeheight.For this reason,seichesare not the controlling           floodeventat PNPP.
Resonance   generatedby wavescan causeproblemsin enclosedwaterbodiessuchas harborsand bayswhenthe periodof oscillation          of the waterbodyis equalto the period of theincoming  waves.However,      thePNPPsiteis notlocatedin anenclosed         embayment.
Additionalty,the period   of oscillationof Lake  Erienear  the PNPP   siteis determined  to be in the rangeof 11 to 15 hours.Thisis much       greater  thanthat of the peak  spectral period of the incidentshallowwaterstormwaves.Consequently,             resonance   is not a detriment at PNPPduringthe criticalPMWSevent.
PERRYNUCLEAR        POWERPLANT                                                             Page23 of 35

NTTF Recommendation     2.1 (HazardReevaluations):   Flooding                           Revision0 FirstEnergyCorporation                                                           February23,2415 ProbableMinimumLow WaterLevelresultingfrom the PMWS Simulations of all the candidatePMWSstormeventsshowthatthe criticalPMWSevent thatwoutdresultin probabte    minimumlowwaterlevel(drawdown)       is thetranspositioned November1998stormeventmaximized           overthe PNPPsite.Thisstormhad the most intensesoutheasterly   windsof the examinedstormevents,witha maximumwindspeed of 93 miles/hour. The  probableminimumlowwaterelevation      (drawdown)   associated with the transposed  November1998storm      produces   a probable  minimum   low water levelof 563.0feetNGVD29 nearthe PNPPsite.The invertsof the PNPPintake              portsare at an averageelevationof 552.65feet NGVD29.
3.6. TsunamiAssessment(ReferencePNPP2015m)
NUREG/CR-6966    identifies thatearthquakes, landslides,  and volcanoescan initiatetsunamis, with earthquakesbeing the most frequentcause. Dip-slipearthquakes(due to vertical movement)are more efficientat generatingtsunamisthan strike-slipearthquakes             (due to horizontalmovement). To generatea majortsunami,a substantial      amountof slip   and a large ruptureareais required. Consequently, onlylargeearthquakes    withmagnitudes    greaterthan6.5 generateobservable   tsunamis.
3.6.1. Basisof Inputs o NationalCenterfor Earthquake      Engineering  Research  (NCEER)database
          . NaturalResources      Canadaseismicity  data
          . NOAAnaturalhazardstsunamidatabase
          . NOAAnaturalhazardsvolcanodatabase o OhioDepartment       of NaturalResources  (ODNR)seismicity    data o USGSearthquake        hazards program  database 3.6.2. GomputerSofhrarePrograms
          . None 3.6.3. Methodology As identifiedby NUREG/CR-7046,      tsunamiassessment      is referenced  to NUREG/CR-6966andNOAATechnical        Memorandum    OAR   PMEL-136. In addition,the morerecently issued NRC guidance,JLD-lSG         -2012-06,   also addresses    tsunami    assessment.
However,JLD-ISG     -2012-OO providesguidanceon detailedtsunami         modeling  and is beyondthe scopeof thisassessment.      Technical  Memorandum     OARPMEL-136      reflects a similartsunamiscreening    assessment  described  by NUREG/CR-6966.
TheNUREG/CR-6966        screening assessment  is basedon a regional  screening anda site screening. The regionalscreening   consistsof researching   historicalrecordsfor tsunami recordsand the potentialfor tsunami-generating    sources.The site screeningevaluates thesitebasedonthehorizontal     distancefroma coast,thelongitudinal   distance measured alonga river,and the    grade elevation in comparison  to the  effects of a tsunami. This assessment  approachis basedon a reviewof historical    records and  databases.
NUREG/CR-6966       identifiesthat tsunamis are generatedby rapid, large-scale disturbances  of a bodyof water.The mostfrequentcauseof tsunamisis an earthquake; however,landslides   andvolcanoes  can alsoinitiatetsunamis.Becauseof the tsunami-generationsequenceassociated     withearthquakes,   dip-slipearthquakes   (dueto vertical movement)  aremoreefficientat generating   tsunamisthanstrike-slip  earthquakes   (dueto horizontalmovement). Furthermore,to generatea majortsunami,a substantial      amount PERRYNUCLEARPOWERPLANT                                                                Page24 of 35

NTTFRecommendation       2.1 (HazardReevaluations):   Flooding                             Revision  0 FirstEnergyCorporation                                                             February   23,2415 of slipand a largeruptureareais required.Consequently,          onlylargeearthquakes      with magnitudes    greaterthan6.5generateobservable       tsunamis.
As partof the assessment,    the NOAAnaturalhazardstsunamidatabaseis usedto review historicaltsunamieventsand associatedrunupsfor the eastcoastof the UnitedStates andCanada.Of the totalevents,therewere7 tsunamieventsthatproduced14 runups occurring  in the GreatLakesregionfrom1755to 1954.TheUSGShazardfaultdatabase findingsare reviewedfor strongearthquakes       or the verticaldisplacements    necessary   to inducea tsunami.Additionally,       the USGSearthquakehazardsprogram,the NCEER database,and the NaturalResourcesCanadadatabaseare reviewedfor historical earthquakes    in the region.
ODNRdata is atsoreviewedfor earthquake-generated             tsunamiand landslide-induced tsunami.Lastly,the NOAA naturalhazardsvolcanodatabaseis reviewedto assess volcanoes   in the LakeErieregion.
3.6.4. Results According   to ODNR,an earthquake-generated      tsunamiin LakeEriewouldrequirea very large earthquakeon the order of magnitude7.A or greaterand significantvertical displacement. Historically,in the LakeErie region,the largestearthquakes         are in the magnitude    5.0range.Preliminary    analysisof post-glacial sediments  in the regionhasnot yieldedevidenceof a largeearthquake        in the last few thousandyears.Furthermore, earthquakesin the region,for which         sufficient  data are available,show primarily horizontalrather than verticalmovement,which is not as conduciveto tsunami generation.
Tsunamiscan alsobe generatedby the downslopemovementof a verylargevolumeof rockor sediment,     eitherfroma rockfallabovethe wateror froma submarine           landslide.
Althoughlargeamountsof unconsolidated         sedimentsare washedinto        Lake   Erie each year when shorelinebluffsare undercutby wave action,these masseslack sufficient volumeand rapidcollapseto displacea volumeof waterthatwouldcreatea tsunami.
LakeErie also has a very gentlebottomprofile,particularly        in the westernand central basins.The easternbasinhassteeperslopes,          but not steep  enough   for a largeamount of sediment   to suddenly flowdownslope   in a submarine    landslide.
The NOArAnsturalhazardstsunamidatabaseidentifiesonly two occurrences                   of non-seiche   (or  non-wind-induced)    tsunami events   in  the  Great  Lakes   region. The   two occurrences    yieldedslightor smallwaveeffects.
The USGSEarthquake        HazardsProgramfaultdatabasecontainsno knownQuaternary faults currentfaults)in thisregionbecausegeologists (or                                                   havenotfoundanyfaultsat the Earth'ssurface.Consequently,       no potentialexistsfor strongearthquakes      or the vertical displacement    necessary   to inducea tsunami.Variousearthquake       databases,    including the USGSEarthquake        HazardsProgramearthquake        database,  the NationalCenterfor Earthquake    Engineering   researchcatalog,and NaturalResourcesCanada,identifythat the largesteventsin thevicinityareno greaterthanmagnitude          5.0.
Lastly,no volcanoes     arelocatedin the LakeErie             accordingto the NOAAnatural hazardsvolcanodatabase.
Tsunamiis not the controllingfloodeventat PNPP.
PERRYNUCLEARPOWERPLANT                                                                  Page25 of 35

NTTF Recommendation      2.1 (HazardReevaluations):  Flooding                       Revision 0 First EnergyCorporation                                                      February23,2015 3.7. GombinedEffectFlood(includingWind-Generated           Waves)(ReferencePNPP20{5q}
Evaluation of floodscausedby precipitation  eventsis coveredin AppendixH.1of NUREG/CR-7046.Thethreealternatives   areaddressed  in floodingon streamsandrivers(Section3.1),which identifiesthe resultingwater surface elevations.Combinedeffect floodingevaluatesthe component   of addedwavesinducedby 2-yearwindspeedalongthe criticaldirection.
Evaluation of floodsalongthe shoresof enclosedbodiesof wateris coveredin AppendixH.4.1 of NUREG/CR-7046     andincludes  onealternative:
Combinationof:
Probablemaximum    surgeandseichewithwind-wave     activity.
The lesserof the 100-yearor the maximumcontrolledwater level in the enclosed bodyof water.
Three alternativesare specifiedin AppendixH.4.2 of NUREG/CR-7046        for streamside locationsof enclosedbodies of water. Each of the alternativesconsideredhas three components              to thewatersurfaceelevation.
contributing Alternative 1 - Gombination of:
The lesserof one-halfof the PMF or the 500-yearflood; Surge and seiche from the worst regionalhurricaneor windstormwith wind-wave activity;and The lesser of the 100-yearor the maximumcontrolledwater level in the enclosed body of water.
a   Alternative 2 - Combination of:
PMF in the stream; A 2S-yearsurge and seichewith wind-waveactivity;and The lesser of the 1OO-year or the maximumcontrolledwater level in the enclosed body of water.
o   Afternative3 -Gombinationof:
           -   A Z5-yearfloodin the stream;
           -   Probable  maximumsurgeandseichewithwind-waveactivity;and
           -   The lesserof the 100-yearor the maximumcontrolled     waterlevelin the enclosed bodyof water.
3.7.1. Basisof Inputs Inputsinclude  thefollowing:
           . MajorStreamall-season      PMFandHEC-RASmodeling       fromCalculation50:38.000
           . MajorStreamcool-season      PMFandHEC-RAS       modeling fromCalculation50:39.000 o MinorStreamall-season      PMFandHEC-RASmodeling       fromCalculation50:40.000 o MinorStreamcool-season      PMFandHEC-RAS       modeling fromCalculation50:41.000 o PMSSfromCalculation       50:47.000 o Waveparameters      for LakeErieat PNPPfromCalculation    50:47.000
           . 1OO-year    or maximumcontrolled  water levelin LakeErie fromCalculation50:46.000
           . LakeEriehistorical   maximum   surgefromCalculation  50:46.000 o LakeErie2S-yearsurgefromCalculation        50:46.000
           . Z-yearwindspeed
           . Sitetopography PERRYNUCLEAR         POWERPLANT                                                  Page 26 of 35

NTTFRecommendation     2.1 (HazardReevaluations):    Flooding                           Revision0 FirstEnergyCorporation                                                          February23,2015 3.7.2. GomputerSofhrvare     Programs
         . ArcGlSDesktop10.1 o   HEC-GeoRAS     10.1 o   HEC-RAS    4.1
         . MicrosoftExcel 3.7.3. Methodology Eachcombination    includescoincident   wind-wave  activity.Coincident  wind-wave   activity is determined for the criticalfloodingcombination  usingthe USACE     guidance  outlined in USACECoastatEngineeringManual.Windsetupis the effectof horizontalstresson the watersurface.Runupis the maximum        elevation of waveuprushabovestillwater     level.
H.4.1Gombination Probablemaximumsurgeand seicheis discussedIn Section3.5. \Mndwaveactivity includeswave height,wind setup,and wave runup.Wave heightand wind setupare includedas partof the PMSSdeveloped       usingDelft3Dmodel.Waverunupis determined in accordance  withUSACEguidanceon the shoreline        and bluffslopesadjacent    to Lake Erie.
H.4.2CombinationAlternatives As a boundingapproach,     the maximumLakeEriewaterlevelfromall threealternatives, includingthe initialwaterleveland surgeeffects,is usedas the downstream           boundary condition for MajorStreamand MinorStreamflooding,and combinedwith             the  PMFfor eachstream.lt is determined     thatthe maximumLakeEriewaterlevelhasno significant effecton the PMFanalyses.      The MajorStreamandMinorStreamHEC-RASmodelsare updatedand the resultsare compared       to the H.1 Combination   resultsto determine  the boundingcombination     for windwaveactivity.The 2-yearwind speedis appliedto the longestfetchlengthbasedon the inundation        areaof the PMF.Waveheightand wind setupare determined    in accordance   with USACEguidance.Significant      waveheightis usedto determine   waverunupin accordance      withUSACEguidanceon verticalwalls.
3.7.4. Results The H.4.1 Combination      maximumwater surfaceelevationis 582.6feet NGVD 29, includingwindsetup,andoccurswestof the powerblockalongtheshoreline            bluffslopes.
The maximumeffectsdueto windwaveactivityoccurat a          location just east of the power block along a sectionof shorelinewith steeperbluff slopes.Wave actionanalysis concludes  thata maximumwaverunupof 27.5 feet maybe generated             on the shoreline bluffslopes.The PMSSmaximumwatersurfaceelevationat this locationis 581.7feet NGVD29. The maximumwaverunupelevation             duringthe controlling PMSSis equalto 609.2feetNGVD29,whichis         well below the site.
The maximumcombinedwatersurfaceelevationfor the MajorStreamand the Minor StreamarethePMFresults.      Thebounding    H.4.2Combination   includes thePMFfor Major StreamandMinorStreamutilizing       the PMSSas a downstream       boundary condition. This resultsin maximumwatersurfaceelevations          equal to the PMF    resultsfor  the Minor Stream.For the MajorStreamthe maximumwatersurfaceelevationsare equalto the PMFresultsupstreamof the plantaccessroad.Downstream           of the plantaccessroadare slightvariances.However,the resultingwaterlevelsare maintained           withinthe Major Streamwatershedboundaries         awayfromthe powerblockand well belowthe nominal PERRYNUCLEARPOWERPLANT                                                               Page 27 of 35

NTTFRecommendation       2.1 (HazardReevaluations):     Flooding                          Revision  0 FirstEnergyCorporation                                                            February   23,2015 finishedfloorelevationof PNPPsafety-related        structures.Therefore,the variancesare minimal.
The MajorStreamis not directlyadjacentto PNPPsafety-related          structures. Therefore, windwaveactivityhasno specificconsequence.
The maximumPMFwatersurfaceelevation            for the MinorStreamas shownin Table1 is 623.0feet NGVD29. Waveactionanalysisconcludes             thata maximumcombinedwind setupand wave runupof 5.3 feet may be generatedon the verticalfaceof the power blockstructures. The maximumwaverunupelevation           duringthe controlling floodingfor the MinorStreamandeastsideof the powerblockis equalto 628.3            feetNGVD     29.
3.8. LocalIntensePrecipitation(ReferencePNPP20159)
The LIP is an extremeprecipitation      eventat a given location.The effectsof the LIP are evaluatedfor the westsideof the powerblock.The effectsof the LIP on the eastsideof the powerblockare identical    to the MinorStreamreevaluation. The LIPevaluation   is performed in accordance withNUREG/CR-7046.
3.8.1. Basisof Inputs
              . Site topography
              . Site-specific,all-seasonPMP o   Combinedprobablemaximumsnowpacksnowmeltand 1O0-year,                   cool-season rainfall
              . Combined1OO-year       snowpacksnowmeltand site-specific,    cool-season   PMP
              . Contributionflow from MajorStream      all-season PMF o   Contributionflow from MajorStreamcool-seasonPMF
              . Contributionflow from MinorStreamall-seasonPMF o   Contributionflow from MinorStreamcool-seasonPMF 3.8.2. GomputerSoftwarePrograms
            . ArcGlSDesktop10.1
            . HEC-HMS       3.5
            . MicrosoftExcel 3.8.3. Methodology The LIP is equalto the all-season,      pointprecipitationPMPor the comblnedeffectsof cool-season   snowmelt   and          The rainfall. three alternativesforthe PMFarealsoevaluated for the effectsof the LlP.Theduration     of the LIP event is 72-hours. The all-season  and coot-season   alternatives  are evaluated  using5-minuteincrements    for various  temporal distributions to maximizerunoff.Front,onethird,center,two-thirds,         and end-loading temporaldistributions     are consideredin an effort to capturethe distribution         that maximizes  runoff.
Thesite is subdivided    intofour (4) sub-basinareasbasedon the topography       of the site.
USACE HEC-HMS hydrologicsoftware is used to convert rainfall to runoff. A rainfall hyetograph is applied to the sub-basin areas and transformed to runoff usingunit hydrograph   methodology. No historical observations  are availableto use as a basisto createa unithydrograph. Therefore, a synthetic unithydrograph is developed. NRCSunit hydrographmethodology                                  transformation.
is usedfor rainfall-to-runoff PERRYNUCLEARPOWERPLANT                                                                 Page 28 of 35

NTTFRecommendation      2.1 (HazardReevaluations):       Flooding                           Revision  0 FirstEnergyCorporation                                                               February  23,2015 The entire roof drainage is assumedto be contributingto the surface runoff.
Conservatively,   no precipitation lossesare incorporated     intothe analysis.Naturallyfor the site area,baseflow is zero.Activeand         passive drainage   systemcomponents    (e.9.,
pumps,gravitystormdrainsystems,smallculverts,and inlets)               were considered   non-functionator cloggedduringthe LIP event, per Case 3 in NUREG/CR-7046.                      No adjustment  of the unithydrographs     is madeto accountfor the effectsof nonlinearbasin response,becausethe unit hydrographs          are developedto conservatively   maximizethe response  time.
The sub-basinareasare modeledas reservoirsusingUSACEHEC-HMShydrologic softwareandan elevation-area      relationship. The reservoirareasare modeledwithbroad crestedweir flow to accountfor outflowlocationsand barrierstructures.Split flow betweenreservoirareasis modeledas an auxiliaryconnectionbetweenthe reservoir areas.Overflowcontributions      from the MajorStreamand MinorStreamare addedas applicable. Outflowfromthe modeldrainsnorthtowardLakeErie.
3.8.4. Results Forthe all-season   PMPevent(Alternative        1),the one-third, center,twothirds,andend-loadingtemporaldistributions      produceidenticalpeak resultsand the maximumwater levels.The maximumwatersurfaceelevationalongthe entirewest side of the power blockfor Alternative  1 is 621.2feetNGVD29.
Basedon the resultsfor Alternative1 onlythe centertemporaldistribution           is evaluated for the combined   probable  maximumsnowpack         and  1OO-year  cool-season rainfallevent (Alternative 2). The maximumwatersurfaceelevationalong             the entirewest  side of the powerblockfor Alternative    2 is 620.0feet NGVD29.
Based on the resultsfor Alternative1 only the centertemporaldistributionis evaluated for the combined1OO-year      snowpackand cool-seasonPMP event (Alternative3). The maximumwater surfaceelevationalongthe entirewest side of the powerblockfor Alternative 3 is 620.2feetNGVD29.
The all-seasonPMP event (Alternative           1) is determined    to be the controllingLIP scenario.The maximumwatersurfaceelevationsat safety-related              structuresalongthe westsideof the powerblockis 621.2feetNGVD29.Thedurationof floodingabovethe nominalfinishedfloorelevation     is t hour3 minutes.
Coincident  wind wave activitycombinedwith the LIP is not designated            by NUREG-CR/7046.Additionally,     site obstructions,   includingstructuresand barrierblocks,and shallowwater depths of floodingon the west side of the power block preclude development    of significantfetchlengthandsubsequent        waveconditions.
: 4. COMPARISON       WITHCURRENT         DESIGNBASIS The reevaluated   maximumwatersurfaceelevations            due to the riverineflooding(PMFfor the MajorStreamand     Minor  Stream,  including  the  combined   effectsof windwaveactivity),   LlP,and lakeflooding(PMSS)exceedthe currentlicensing           basis.
For riverineflooding,the currentdesignbasisincorporates          superseded   guidance,  whichdoes notexaminesub-hourly     PMPincrements,     temporaldistributions,   or theeffectsof nonlinear basin response. In addition,recentsitetopography      is used for the hazard  reevaluation.
PERRYNUCLEARPOWERPLANT                                                                   Page29 of 35

NTTFRecommendation       2.1 (HazardReevaluations):  Flooding                          Revision 0 FirstEnergyCorporation                                                          February 23,2015 Forlakeflooding,   the currentdesignbasisassumesthe surgeactsonlyin onedirection.        A site-specificwind and pressurefield is developedas part of the reevaluation. Morerecentstorms providethe controlling  windfor reevaluated  surgefloodingat PNPP.
As previously  indicated, the PMSSmaximumstillwater     surfaceelevationexceedsthe design basiselevation  of 580.5feetNGVD29 by a maximumvalueof 2.1feet.The UHSfor PNPPis Lake Erie.Althoughthe designbasisis exceeded,the PMSS Stillwatersurfaceelevation remainsbelowthe safety-related     pumpsand equipmentlocatedaboveelevation586.5feet NGVD 29 in the emergencyservicewater pumphouse.             Additionally,the PMSS minimum stillwatersurfaceelevationis lowerthanthe designbasisof 565.26feet NGVD29 by 2.3 feet.
However,previousevaluationdetermined       thatthereis adequatenet positivesuctionheadand submergence    of the emergency   servicewaterpumpsfor a resulting  elevation  as low as 559.0 feet NGVD29 (Reference      PNPP2004).The     maximumsurgerunupexceedsthe designbasis elevationof 607.9feetNGVD29 by a maximumvalueof 1.3feet.However,          the maximumeffects of the PMSSeventare maintained      on the bluffsadjacentto  LakeErie. The  sitegraderemains higherthanthe maximumeffectsof the PMSSevent.          Therefore, the resulting beyonddesign basisPMSSeffectsare inconsequential                      structures.
to safety-related For LIPflooding,the currentdesignbasisreducesthe peakrainfallintensity       to accountfor the roofdrainage  systemandaltowa build-upof six inchesof rainfalldepthovertheentireplantsite.
Additionally,runoffcoefficients (losses)are incorporatedintothe analysis.As partof the hazard reevaluation, recentsitetopography   is used,andno creditis takenfor lossesor the roofdrainage system.Furthermore,     the hazardreevaluationincorporatesoverflowcontributions       from the adjacentMajorStreamandMinorStreamwatersheds.
Thecomparisons     of existingandreevaluated  floodhazardsareprovidedin Table2.
PERRYNUCLEARPOWERPLANT                                                              Page30 of 35

NTTFRecommendation   2.1 (HazardReevaluations):  Flooding                        Revision0 FirstEnergyCorporation                                                    February  23,2015 Table2 - Comparisonof Existingand Reevaluated      FloodHazardsat PNPP Flood-Gausing Mechanism        DesignBasis        Comparison Flood HazardReevaluationResults FloodingIn       MaiorStream           Not          MaiorStream streamsand       PMFElevation      is  bounded. All-seasonPMFElevation   is 630.9 rivers           624.0feet NGVD        Exceeds      feetNGVD29 (at raillinebridge).
29 (at railline       current bridge).              designbasis  All-Season  PMFFlowis 30,100cfs.
for both PMFFlowis             Major        Cool-Season    PMFElevation is 623.1 31,250cfs.            Streamand    feet NGVD29.
Minor Cool-season    is not Stream.      Cool-season    PMFFlowis 14,900cfs.
evaluated.
MinorStream MinorStream                        All-seasonPMFElevation   is 623.0 PMFElevation      is               feetNGVD29.
619.5feet   NGVD
: 29.                                All-seasonPMFFlowis 5,300cfs.
PMFFlowis 7,000                    Cool-season    PMFElevation is 621.1 cfs.                               feet NGVD29.
Cool-season    is not              Cool-season    PMFFlowis 1,600cfs.
evaluated.
Dambreaches      No upstream           Bounded      Damassessment             no indicates andfailures      impoundments.                      watersheddams.
Stormsurge       Watersurface          Not          Watersurfaceelevationis 582.6feet elevation is 580.5    bounded. NGVD29.
feetNGVD29.           Exceeds current Lowwater              designbasis. Lowwaterelevationis 563.0feet elevation is 565.26                NGVD29.
feet NGVD29.
Seiche           Thisflood-causing Bounded          Boundedby stormsurge.
mechanism     is not described specifically for the sitein the USAR.
Tsunami          This flood-causing Bounded         Tsunamiassessment    indicates a slight mechanismis                        possibility           in of tsunamis the Great identifiedas not                   Lakesregion.However,the seismicity applicablein the                   in the regionsuggestsno potential USAR.                              existsfor strongearthquakes  or the verticaldisplacement necessary  to induce  a           tsunami.
substantial PERRYNUCLEAR     POWERPLANT                                                   Page 31 of 35

NTTFRecommendation      2.1 (HazardReevaluations)     : Flooding                              Revision  0 FirstEnergyCorporation                                                                February   23,2415 Table2 - Comparisonof Existingand Reevaluated            FloodHazardsat PNPP(Continued)
Flood-Causing Mechanism       DesignBasis               Comparison Flood HazardReevaluationResults lce-induced        Thisflood-causing Bounded                lce-inducedfloodingis boundedby the flooding           mechanism     is                         all-seasonPMF event.
identified as not plausible in the USAR.
Channel            Thisflood-causing Bounded                Channeldiversion     is notcharacteristic migration or       mechanism     is                         for adjacentstreams.
diversion          identified as not applicable   in the USAR.
Combinedeffect     Waverunupon               Not            Waverunupon LakeErieshoreline flood(including    LakeErieshoreline bounded.               bluffsis 609.2feet NGVD29.
wind-generated     bluffsis 607.9feet Exceeds waves)             NGVD29.                   current Maximum     waverunupelevation       in the designbasis.
vicinityof the  power  block  is 628.3  feet
                    \Mndwaveeffects on streamsis not                         NGVD29.
described   in the USAR.
LIP                Maximum    water          Not            Maximumwatersurfaceelevationis surfaceelevationis bounded.              621.2feet NGVD29.
620.5feetNGVD Exceeds
: 29.                       current desiqnbasis.
Plantmonument   elevations,   usedas a basisfor plantdesign,havebeenreportedto havean approximate 0.21feet uncertainty     with respectto the 2012Sanborntopographic         survey,being the surveybasisof floodingevaluations.      The approximate   0.21 feet  uncertainty  ls in excessof the estimated0.11feettolerance      of the 2012Sanbornsurvey.The0.11        feet tolerance  accounts for surveyaccuracyas well as for the accuracyof the conversionbetweenNAVD88 to NGVD 29 datums.The0.21feetuncertainty        shallbe considered in addition to thestated0.72feetonsite conversionbetweenthe NADV88 andNGVD29 datums.Thus,accounting                   for an additional  0.21 feetof waterdepthat elevations    listedherein.However,sincethe Reportshowsthatfloodlevels exceedthe designbasisfloodlevels,the conclusion significantly                                                       of thisreportis unchanged,      an interimactionplan has beendetermined         necessary. The interimaction     plan  as  stated  in the followingsectionwillaccountfor thisdiscrepancy      andthe powerblockbuildingsettlement          of up to 1.5inchesdiscussed  in Section2.3,withinthe listedmodifications      as wellas in allfinaldesign basisconditions.
PERRYNUCLEAR       POWERPLANT                                                              Page32 of 35

NTTFRecommendation        2.1 (HazardReevaluations):    Flooding                             Revision0 FirstEnergyCorporation                                                                February23,2015
: 5. INTERIM     AND PLANNEDFUTURE            ACTIONS TheFlooding    HazardReevaluation      Reportevaluated  theapplicable   floodinghazardsfor PNPP.
Four of the postulatedreevaluated         flood hazardevents (riverineflooding,lake flooding, combinedeffects,and LIP)resultedin maximumfloodwaterelevations                higherthanpreviously calculated  for PNPP.Thesepostulated        floodingeventsare considered       beyonddesignbasis eventsanddo notconstitute       an operabilityconcern.The PMSSeventandthe combinedeffects for waverunupon the LakeErieshoreline         resultsareinconsequential. Therefore,  no interimor futureactionsare plannedfor thisevent.
The interimaction plan is an engineeringchangepackageand supportinganalysesto demonstrate    maximumwatersurfaceelevations         will not resultin floodingof plantbuildings important  to nuclearsafety.An engineering      changepackagehas beeninitiatedto implement designchangesto theMajorStreamandtheMinorStreamto addressthedesignbasiscondition describedin the functionalityassessment(PNPP ConditionReport 2013-05625)and accommodate     the beyonddesignbasisevents.Althoughthe functionality          assessment   removes someof the conservatism      appliedin the originalevaluation,  the resultsfor the MinorStreamon the eastsideof the powerblockandthe LIPresultson the westsideof the powerblockwere equalto or less than the nominalfinishedfloor elevationof PNPPsafety-related              structures.
Therefore,  no additional  interimactionsarenecessary.
The designchangeswill ensurethat all flow will be maintained              withinthe Major Stream watershed   boundaries    andwithinthe banksof the MinorStream.       Because    the MajorStreamis not immediately    adjacentto safety-related   structures,the resulting   water   levelsin the Major Streamare inconsequential.      However,overflowfromthe MajorStream         is a contributor to Minor Streamwatertevels.Therefore,       flowneedsto be maintained    withinthe  Major   Stream watershed boundaries.
Theengineering     changepackageincorporates      removalof a portionof the existingabandoned rail lineembankment      crossingthe MajorStream.Removalof the embankment             allowsgreater conveyance    of flow in the overbanksof the MajorStream,preventing       flowfromovertopping    the railline.Furthermore,    the secondaryaccessroadis raisedto preventany remainingbackwater fromovertopping     the road.Thismodification   resultsin the concentration   of MajorStreamrunoff to be carrieddownstream       to LakeErie,ratherthan contributing    to runoffto otherareasof the site.Thetechnical    basisof the MajorStreammodifications     incorporates   analysisof site-specific PMP as input,no precipitation       losses,unit hydrograph   rainfall runoff analysis,includingthe etfectsof nonlinear   basinresponse,   andone-dimensional     unsteady  state  hydraulic modeling.
Theengineering     changepackageincorporates      an upstream   diversion  of the MinorStream.The diversionchanneldivertsrunofffloweastaroundthe outsideof the securitybarriersand north directlyto LakeErie.A bermis designed       adjacentto thediversion   channelbetweenthechannel and the site.UnderPMFconditions         the bermwill maintainall floodwaterawayfromthe site.
Thesemodifications     significantly reducethe runoffflowreceivedby the MinorStream,resulting in the designbasiswaterlevelsof 619.5feetNGVD29.Withthe designbasiswaterlevels,the combinedeffectwind wave activityrunupon the powerblockis no longerapplicable.                    The technical basisof the MinorStreammodifications      incorporates   analysisof Hydrometeorological No.33 PMPas input,no precipitation       losses,unithydrograph     rainfallrunoffanalysis,  including the effectsof nonlinearbasin response,and one-dimensional                 unsteadystate hydraulic modeling. Hydrometeorological     No.33 PMPis determined      to boundsite-specific   PMP.
Thesechangeswill resultin eliminating       the overflowcontributions   fromthe MajorStreamand the MinorStreamto other areasof the site. Therefore,only the precipitation               for the LIP contributes  to flooding.Supporting    the engineering  changepackage,the interimactionplan includes  completion   of an LIPanalysis to determine the maximum     watersurfaceelevation. Also, the evafuation   will addressthe 0.21feetdatumdiscrepancy,         discussedin Section4, andthe PERRYNUCLEARPOWERPLANT                                                                    Page33 of 35

NTTFRecommendation     2.1 (HazardReevaluations): Flooding                          Revision0 FirstEnergyCorporation                                                        February23,2015 powerblockbuildingsettlement  of up to 1.5inchesdiscussed   in Section2.3.The resultsof this analysiswillbe incorporatedintothe engineering changepackage.
: 6. REFERENCES (ANSI/ANS-2.8-1992)  ANS,AmericanNationatStandard     for Determining  DesignBasrsFlooding at Power ReactorSr'fes,Preparedby the AmericanNuclearSocietyStandardsCommittee WorkingGroupANS-2.8,1992.
(JLD-ISG-2013-01)  NRC,Guidancefor Assessment      of FloodingHazardsdue to Dam Failure, Revision 0, July2A13.
(JLD-ISG  -2012-06)NRC,Guidance   for Performinga Tsunami,   Surgeor SeicheFlooding  Hazard Assessment,   Revision0, January2013.
(NEfAugust2012)NEl, Report12-08,Overviewof ExternalFloodingReevaluations,            August 2012.
(NRCMarch2012)NRC,LettertoLicensees,        RequestforInformation   Pursuantto Title10of the Codeof FederalRegulations  50.54(0Regarding   Recommendations     2.1,2.3,and9.3of theNear-TermTaskForceReviewof Insights     fromthe Fukushima   Dai-ichiAccident,March12,2012.
(NRCMay 2012)NRC,Letterto Licensees,                    of ResponseDue Datesfor Request Prioritization for Information Pursuantto Title 10 of the Code of FederalRegulations     50.54(f)Regarding FloodingHazardReevaluations   for Recommendation    2.1 of the Near-Term  TaskForceReview of lnsightsfromthe Fukushima  Dai-ichiAccident,May 11,2012.
(NRC RG 1.59)NRC,DesrgnBasisFloodfor NuclearPower Plants,RegulatoryGuide Revision 2, 1977.
(NRCRG 1.102)NRC,Ftood Protection        for NuclearPower Plants,Regulatory    Guide1.102, Revision  1, 1976.
(NUREG-O8OO)    NRC,NUREG-0800,      Standard ReviewPtanfor the Reviewof SafetyAnalysis Reporfs for NuclearPower Ptants:LWR Edition- Sde Characterisficsand Site Parameters (Chapter2), ML070400364,   March2007.
(NUREG/CR-7046)    NRC,NUREG/CR-7046,       PNNL-20091   , Design-Basis  FloodEstimationfor SiteCharacterizationat NuclearPower Ptantsin the UnitedSfafes    of America,ML11321A195, November   2011.
(NUREG/CR-6966)    NRC,NUREG/CR-6966,       TsunamiHazardAssessmentat Nuclear       Pawer PtantSifesin the lJnitedSfafesof America,NationalTechnical    InformationService,March 2009.
(ODNR2013)OhioDepartment      of NaturalResources,   ProbableMaximumPrecipitation    Study for the Sfafeof Ohio,preparedby AppliedWeatherAssociates,      LLC, February2013.
(PNPP2OO4)    FENOCCalculation   P45-081,Evaluation  of Nef PositiveSuctionHead(NPSH) and SubmergenceRequirements     for the Emergency  Service  Water(ESW SysfemPumps, Revision  0.
(PNPP2015a)FENOCCalculation       50:36.000, PNPPSde-Specific     All-SeasonPMP,Revision  0.
(PNPP2015b)FENOCCalculation       50:37.000, PNPPSde-specific     Cool-season PMP,Revision 0.
PERRYNUCLEAR       POWERPLANT                                                    Page34 of 35

NTTFRecommendation   2.1 (HazardReevaluations): Flooding                     Revision0 FirstEnergyCorporation                                                February23,2015 (PNPP 2015c) FENOCCalculation50:38.000,PNPPMajor StreamAll-SeasanProbable MaximumFlood,Revision0.
(PNPP2015d)FENOCCalculation       50:39.000,PNPPMajor StreamCool-Season    Probable MaximumFlood,Revision0.
(PNPP 2015e) FENOCCalculation50:40.000,PNPPMinor StreamA//-SeasonProbable MaximumFlood,Revision0.
(PNPP20150 FENOCCalculation       50:41.000,PNPPMinor StreamCool-Season    Probable MaximumFlood,Revision0.
(PNPP20159)FENOCCalculation50:42.000,PNPP Effectsof Local lntensePrecipitation, Revision0.
(PNPP2015h)FENOCCalculation     50:43.000, PNPPDamsAssessmenf,  Revision0.
(PNPP 2015i) FENOC Calculation50:44.000,PNPP lce Jam and Channel Assessmenf,Revision0.
(PNPP2015j)FENOCCalculation    50:45.000, PNPPWindClimatology,        0.
Revision (PNPP2015k)FENOCCalculation     50:46.000, PNPPSurgeand SeicheScreemng,  Revision 0.
(PNPP20151) FENOCCalculation   50:47.000,PNPPSurgeand SeicheAnalysis,  Revision0.
(PNPP2015m)FENOCCalculation      50:48.000,PNPPTsunami  Assessment,Revision0.
(PNPP2015n)FENOCCalculation     50:52.000, PNPPRainfallRunoffGISAnalysis,Revision0.
(PNPP2015o)FENOCCalculation     50:53.000, PNPPSurgeand SeicheG/S Analysis,Revision 0.
(PNPP2015p)FENOCCalculation     50:54.000, PNPPSurgeand SeicheCalibration,Revision0.
(PNPP2015q)FENOCCalculation     50:55.000, PNPPCombinedEvents,         0.
Revision (PNPP2015r)FENOCCalculation     50:59.000,PNPPSde-SpecificAll-SeasonSub-Hour ProbableMaximumPrecipitationAnalysisfor 1-10SquareMiles,Revision0.
(PNPP2015s)FENOCCalculation     50:60.000,                Cool-Season PNPPSife-Specific          Probable Maximum(rainfall)PrecipitationAnalysis,Revision0.
(USAR)PerryNuclearPowerPlant,UpdatedSafetyAnalysisReport,Revision17.
PERRYNUCLEARPOWERPLANT                                                    Page35 of 35}}