Text

Monticello Nuclear Generating Plant - Response to an Apparent Violation in NRC Inspection Report 05000263/2013008 (EA-13-096)
	ML13233A068
Person / Time
Site:	Monticello
Issue date:	07/11/2013
From:	Schimmel M A; Northern States Power Co, Xcel Energy
To:	; Document Control Desk, NRC/RGN-III
References
	EA-13-096, L-MT-13-062 IR-13-008
	Download: ML13233A068 (99)
	v • d • e

Monticello Nuclear Generating PlantXcelEnergy 2807 W County Road 75Monticello, MN 55362July 11, 2013 L-MT-13-062EA-13-096U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001Monticello Nuclear Generating PlantDocket 50-263Renewed Facility Operating License No. DPR-22Response to an Apparent Violation in NRC Inspection Report 05000263/2013008(EA-1 3-096)References: 1) Letter from Nuclear Regulatory Commission (NRC) to Mr. Mark A.Schimmel, "Monticello Nuclear Generating Plant, NRC InspectionReport 05000263/2013008; Preliminary Yellow Finding," dated June11, 2013 (Accession Number ML13162A776)2) Letter from Northern States Power -Minnesota to NRC, "Notificationof Intention Regarding NRC Inspection Report 05000263/2013008(EA-13-096)," dated June 19, 2013By the above referenced letter dated June 11, 2013, the NRC transmitted InspectionReport 05000263/2013008 for the Monticello Nuclear Generating Plant (MNGP). In theinspection report, the NRC identified one finding and apparent violation with apreliminary significance of Yellow for MNGP. In the referenced letter, the NRC statedthat the site had failed to maintain a flood procedure, A.6, "Acts of Nature", such that itcould support the timely implementation of flood protection activities within the 12 daytimeframe credited in the design basis, as stated in the updated safety analysis report(USAR).Northern States Power Company -Minnesota (NSPM) reviewed the apparent violationand, pursuant to the provisions of the choice letter, prepared a written response to theapparent violation. NSPM agrees that the failure to maintain a flood plan to protect thesite from external flooding events is a violation of Technical Specification 5.4.1.a.This letter submits additional information for the NRC's consideration in its finaldetermination of the significance of the apparent violation. The enclosures address thefollowing:e-7A Document Control DeskL-MT-1 3-062Page 2 of 5Response to Apparent Violation (Enclosure 1)NSPM agrees that the failure to maintain an adequate flood plan to protect the site fromexternal flooding events is a violation of Technical Specification 5.4.1 .a. NSPM is takingthis failure to protect the site from external flooding very seriously and has used it toreinforce NSPM's policy and commitment to safety as a top priority in our EmergencyResponse plans, response to acts of nature, and effective corporate governance andoversight. The site and nuclear fleet are taking corrective actions to ensure protection ofthe radiological health and safety of the public in the event of an external flooding worstcase scenario. A summary of the corrective actions to resolve the performancedeficiency is presented in Enclosure 1.As part of those actions, NSPM is performing cultural assessments focusing on decisionmaking, effective communication, and closure follow-through not only at the site levels,but across the nuclear fleet to maximize learning from this situation.Probabilistic Risk Analysis (Enclosure 2)NSPM developed additional information providing further insight into the probability of aProbable Maximum Flood (PMF) at the Monticello site for the NRC's consideration. Thereport provides probabilistic risk analyses to support a best-estimate assessment of thesignificance of this finding as well as bounding analyses to support final significancedetermination prior to corrective actions taken by the site. The best-estimate analysisincorporated the assumptions necessary to support the assessment of a finding relatedto an external flooding event. Results are shown in the table below:Nominal, Best Sensitivity 1: Sensitivity 2:Estimate Bounding Flood SPAR-H HRAFreauencv ProbabilitiesCDF 1.04E-06 3.1 OE-06 1.83E-06ACDP 8.92E-07 2.66E-06 1.57E-06The full results of the event tree quantification are summarized in Enclosure 2.Monticello Nuclear Generating Plant Flood Protection Analysis (Enclosure 3)The postulated PMF for the MNGP is compared to other site Mississippi river conditionsin the table below. The PMF is not an instantaneous event, but rather a slowlydeveloping evolution that allows for plant staff to monitor, predict, prepare, andimplement appropriate actions to provide the required flood protection. Since actionshave been taken to procure the bin wall and levee materials, performance of areasonable simulation demonstrated that the levee and bin wall system can now beinstalled within the available time as defined in the licensing basi Document Control DeskL-MT-1 3-062Page 3 of 5Normal and Flooded River Flow Rates and Water ElevationsMississippi River Flow Rate (cfs) Water ElevationCondition (ft. msl)Normal 4,600 905Maximum Recorded 51,000 916(1965)1000 Year Flood -90,000 (1) 921Probable Maximum 364,900 939.2Flood 364,900_ 939.2A report entitled "Monticello Flood Protection," was prepared for Monticello andaddresses the aspects of flood protection for which MNGP was licensed and is includedin Enclosure 3.Annual Exceedance Probability (Enclosure 4)Annual river exceedance probabilities based on annual peak flood estimates at theMonticello site were developed to support the probabilistic risk assessment. Theprobability of a PMF at the site was determined to be extremely low.Enclosure 4 provides a copy of the report entitled, "Annual Exceedance ProbabilityEstimates for Mississippi River Stages at the Monticello Nuclear Generating Plant basedon At-site Data for Spring and Summer Annual Peak Floods", June 28, 2013, developedby RAC Engineers & Economists.Stakeholder Outreach (Enclosure 5)NSPM hosted an open house to share information with its community neighbors on itsoperations and preparedness to handle potential emergencies and how it would respondto flooding, earthquakes and other unforeseen challenges.The key message presented to visitors was that safety and security at the NSPM nucleargenerating plants are top priorities for Xcel Energy. Further, that we understand theindustry, NRC, and public's demand of higher safety standards and flood preparednessat the nation's nuclear power plants in the wake of events such as 9/11 and FukushimaDaiichi. The Monticello Flood Protection Strategy was identified and explained todemonstrate that the site is capable of withstanding a PMF and that the site isincorporating lessons learned from the industry to improve and assure protectionmethods.Safety Culture ReviewNSPM agrees it missed an opportunity within its control to identify challenges to theimplementation of the A.6 procedure, leading to the identified apparent violation. Assuch, NSPM assembled an expert panel to examine the behavioral and cultural aspectsimpacting decision making within the nuclear business unit. This activity was chartered Document Control DeskL-MT-13-062Page 4 of 5as an immediate and interim measure preceding the extensive root cause evaluationthat will be performed to identify the full magnitude of this issue, associated causes, andcorrective actions to prevent recurrence.This expert panel assembled to examine safety culture within its nuclear organizationwas comprised of five independent consultants and one Xcel representative. The teamreported directly to the Vice President of Nuclear Operations Support. A phasedapproach is being utilized to examine the behavioral and cultural aspects impactingdecision making within the nuclear business unit. Three phases are planned to examinethis subject: Phase (1) is specifically focused on the Monticello flooding issue, Phase (2)more broadly examines Monticello issues and Phase (3) examines Prairie Island issues.While the phases are specific to the individual sites, the scope includes developing anunderstanding of the corporate culture and influence beyond a site-centric examinationof the behavioral and environmental influences. To date Phase (1) has been completedwith scheduling of Phase (2) and (3) expected to commence and complete over the nextfew months. The initial phase identified improvement opportunities in the areas ofdecision making, leadership behaviors, and questioning attitude regarding the station'spreparedness for a PMF. The results of this assessment have been insightful and will beapplied across the nuclear fleet to ensure a healthy safety culture exists. Opportunitieshave been identified to strengthen fleet and Nuclear Oversight accountability forproviding oversight to proactively detect performance gaps.Interim actions are in place for the short term to focus on the areas for improvement, andlonger term actions are in development.SummaryNSPM respectfully requests that the NRC consider the enclosed information in its finaldetermination of the significance of the finding. Notwithstanding our assessment of thesignificance of the finding, NSPM clearly understands our performance shortcomingsconcerning flood protection for the entire spectrum of possible flooding events at theMNGP. Corrective actions have already been completed to address the NRC's identifiedperformance deficiency. Additionally, we unequivocally acknowledge the need for overallperformance improvement at MNGP. Actions are underway to ensure that the lessonslearned from this finding are applied more broadly to overall performance.Summary of CommitmentsThis letter contains no new commitments and no revisions to existing commitments.Mark A. SchimmelSite Vice-PresidentMonticello Nuclear Generating PlantNorthern States Power Company-Minnesota Document Control DeskL-MT-1 3-062Page 5 of 5

Enclosures:

Enclosure 1 -Response to Apparent ViolationEnclosure 2 -External Flooding Evaluation for Monticello NuclearGenerating PlantEnclosure 3 -Monticello Flood ProtectionEnclosure 4 -Annual Exceedance Probability EstimatesEnclosure 5 -Stakeholder Outreachcc: Regional Administrator, Region III, USNRCProject Manager, Monticello Nuclear Generating Plant, USNRCResident Inspector, Monticello Nuclear Generating Plant, USNRC Enclosure IResponse to Apparent ViolationEA-1 3-096NRC Inspection Report 05000263/2013008Monticello Nuclear Generating Plant3 Pages Follow Northern States Power Company -MinnesotaResponse to Preliminary Yellow FindingNRC Finding SummaryThe inspectors identified a preliminary Yellow finding with substantial safety significance andassociated apparent violation (AV) of Technical Specification 5.4.1 for the licensee's failure tomaintain a flood plan to protect the site from external flooding events. Specifically, the site failedto maintain flood Procedure A.6, "Acts of Nature," such that it could support the timelyimplementation of flood protection activities within the 12 day timeframe credited in the designbasis as stated in the updated safety analysis report (USAR).The inspectors determined that the licensee's failure to maintain an adequate flood planconsistent with the USAR was a performance deficiency, because it was the result of the failure tomeet the requirements of TS 5.4.1 .a, "Procedures;" the cause was reasonably within thelicensee's ability to foresee and correct; and should have been prevented. The inspectorsscreened the performance deficiency per Inspection Manual Chapter (IMC) 0612, "Power ReactorInspection Reports," Appendix B, dated September 7, 2012, and determined that the issue wasmore than minor because it impacted the 'Protection Against External Factors' attribute of theMitigating Systems Cornerstone and affected the cornerstone's objective to ensure theavailability, reliability, and capability of systems that respond to initiating events to preventundesirable consequences (i.e. core damage). Specifically, if the necessary flood actions cannotbe completed in the time required, much of the station's accident mitigation equipment could benegatively impacted by flood waters.NRC Baseline Significance Determination Process ReviewAs part of the process, the Region III Senior Reactor Analyst (SRA) developed an event treemodel to perform a bounding quantitative evaluation. The model presents an external flood eventthat exceeds grade level (930 ft. MSL) and requires implementation of Procedure A.6, "Acts ofNature" Section 5.0.NSPM ResponseNSPM agrees that a performance deficiency exists. Procedure A.6, "Acts of Nature", at the time ofthe violation, did not provide sufficient guidance to execute mitigation strategies for a probablemaximum flood (PMF) event. Adequate management oversight and engagement was notprovided to ensure that the Monticello external flood mitigation procedure and strategies metexpected industry standards and licensing basis requirements.Actions have been completed to reduce the flood mitigation plan timeline by pre-stagingequipment and materials required for bin-wall levee construction, improving the quality of theA.6 "Acts of Nature" procedure and pre-planning work orders necessary to carry out the A.6actions.Summary of Corrective Actions:Acquired materials required for flood mitigation including, but not limited to:" Hardware and components for construction of Bin-Wall" Clay for levee construction (30000 cubic yards)* Rip-Rap stone for levee construction (1700 cubic yards)Page 1 of 3

Sand for levee construction and filling sandbags (11000 cubic yards)" Sand bagging machine (Capacity 1600 sand bags/hr)* Manual sand bag filling tools (25 on site)" Gas Sump Pumps* Electric Sump Pumps" Crushed concrete for alternate road access (2400 cubic yards)* Preventative maintenance plans are being developed for new flood mitigation equipment* Performance of reasonable simulation of major steps required by procedure A.6 "Acts ofNature" Section 5.0, including building of bin-wall sections, sandbagging, placement ofvarious covers, and relocation of vital equipment.* Extensive procedure revisions to enhance feasibility of actions and reduce overall timerequired to execute the strategy.* Table top exercises of new revisions performed to ensure practicality.* Development of work orders to provide more detail for execution of steps within procedureA.6, "Acts of Nature" Section 5." The existing flood prediction surveillance was revised to occur on a monthly basis insteadof yearly and contains provisions to continually monitor river predictions if certainconditions are met.* Meetings with the National Weather Service were held to develop more robust predictioncapabilities and options.* Enhanced construction drawings of levee and bin-wall to provide more detail* Updated existing contracts and memorandums of understanding with vendors to assureequipment availability.* A modification is also in the design phase to install the base of the bin-wall on the westside of the Intake structure, simplify construction on the east side of the Intake Structure,and also update the steel plate design for protection of the Intake Structure.Review of NRC Significance DeterminationNSPM has developed additional information providing new insight into the probability of a PMF atthe Monticello site for your consideration. A report entitled "External Flooding Evaluation forMonticello Nuclear Generating Plant" was prepared by Hughes Associates, Inc., for NSPM. Thereport provides a best-estimate assessment of the significance of this finding. Two (2)sensitivities were performed to assess the bounding risk, addressing some of the uncertaintyassociated with this assessment.The first sensitivity study provides the risk assessment if a bounding annual exceedanceprobability is assumed. As noted in the Hughes' report, the uncertainty associated with extremeflooding can be addressed by artificially restraining the AEP to a value of no less than 1 E-05/year.When this restraint is assessed, the ACDP is 2.66E-06.Enclosure 4 of this letter provides a copy of the report entitled, "Annual Exceedance ProbabilityEstimates for Mississippi River Stages at the Monticello Nuclear Generating Plant based on At-site Data for Spring and Summer Annual Peak Floods", June 28, 2013, developed by RACEngineers & Economists.The second sensitivity address the different methodologies available for quantifying the HumanError Probability (HEP) associated with the manual operation of RCIC (Reactor Core IsolationCooling) and HPV (Hard Pipe Vent). This sensitivity provides quantification using The SPAR-HPage 2 of 3 Human Reliability Analysis Method, NUREG/CR-6883. When the simplified SPAR-Hmethodology is used, the assessment results in a ACDP of 1.57E-06.The result of the nominal, best-estimate assessment and the two (2) sensitivities performed areshown in the table, below, for ease of reference.Sensitivity 1:Bounding FloodFrequencySensitivity 2: SPAR-HHRA ProbabilitiesNominal Best-EstimateCDF 1.04E-06 3.1OE-06 1.83E-06ACDP 8.92E-07 2.66E-06 1.57E-06Enclosure 2 of this letter provides a copy of a report entitled, Report Number 1SML16012.000-1,"External Flooding Evaluation for Monticello Nuclear Generating Plant," developed by HughesAssociates for consideration.Page 3 of 3 Enclosure 2Monticello Nuclear Generating Plant"External Flooding Evaluation for Monticello Nuclear Generating Plant"ISMLI16012.000-1Hughes Associates62 Pages Follow

.IHUGHESEASSOCIATESENGINEERS CONSULTANTS SCIENTISTSExternal Flooding Evaluation for MonticelloNuclear Generating Plant1SML16012.000-1Prepared for:Xcel EnergyProject Number: 1SML16012.000Project Title: Monticello External Flooding SDPRevision: 1Name DatePreparer: Erin Collins/Paul Amico/Suzanne Loyd 7/8/2013~ ~" Erin P. Collins2013.07.082018:01 -04-00-Reviewer: Pierre Macheret 7/8/2013P.",: 2"13 007 .M0 1-. o U.Review Method Design Review E] Alternate Calculation E]Approved by: Francisco Joglar Francisco Joglar. ,. 7/8/2013N. I l: "013.07-

ISML-16012.000-1 Table of ContentsSUMMARY... .._*__"___._."_ __.___ '._____HEP Sumrnhiaty :. ..: .., .-. -.. ..Pcog Pexe Total HEP ErrorFactorMethod CBDTM THERP CBDTM + THERPWithout Recovery 3.le-02 2.3e-01With Recovery 6.1e-04 1.3e-02 1.3e-02 5Initial Cue:Drywell pressure above 2 psigCue Comments:The cue for action is that the TSC has recommended venting the DW by using the Hard Pipe Vent usingprocedure A.8-05.08, Manually Open Containment Vent Lines.Initial procedure entered on high drywell pressure is C.5-1200. The DW/Torus Pressure leg directsoperators to C.5-3505. For the limiting PRA case, it is assumed that normal and alternate nitrogen andpower via Y-80 is not available and operators must therefore use A.8-05.08 to install pre-staged nitrogenbottles directly to the inboard and outboard HPV isolation valves to open them.Due to the SBO, it is assumed that there will be multiple impacts to indications, so the degree of clarityhas been set at "Poor".Degree of Clarity of Cues & Indications:PoorProcedures:Cognitive: C.5-1200 (PRIMARY CONTAINMENT CONTROL flowchart (Monticello)) Revision: 16Execution: A.8-05.08 (Manually Open Containment Vent Lines) Revision: 1Other: A.6 (ACTS OF NATURE (Monticello)) Revision: 43Other: C.5-3505-A 0 Revision: 10Cognitive Procedure:Step: DW/TORUS PRESSURERevision 2 Page A-19Revision 2Page A-1 9 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSInstruction: BEFORE DW pressure reaches Fig. D, DW Pressure Limit (56 psig) vent to stay below Fig. D,DW Pressure Limit per C.5-3505Procedure and Training Notes:Three JPM trials were performed emulating the specific external flooding conditions of this scenario on 18June 2013. Observations were factored into this analysis.Training:Classroom, Frequency: 0.5 per yearSimulator, Frequency: 0.5 per yearJPM Procedure:JPM-A.8-05.08-001 (Manually Open Containment Vent Lines) Revision: 0Identification and Definition:This HFE is for the external flooding model for venting prior to core damage.1. Initial Conditions: SBO due to external flooding.2. Initiating Events: External flooding causes station blackout.3. Accident sequence (preceding functional failures and successes):No containment venting or heat removalNeed to vent to maintain containment integrity prior to ultimate containment pressure for RCIC injection4. Preceding operator error or success in sequence: None.5. Operator action success criterion: Align pre-staged alternate nitrogen bottles directly to AO-4539 andAO-4540 (located on the torus catwalk) to open the hard pipe vent.6: Consequence of failure: Failure to vent containment leads to containment failure. Any subsequentrelease will likely be through an unscrubbed and unfiltered release path.Key Assumptions:JPM A.8-05.08-001, Rev. 0, Manually Open Containment Vent LinesINITIAL CONDITIONS:o Extreme flooding has led to a Station Blackout that has. existed at Monticello for the last 10hours.o Div. 1 and Div 2 250 VDC battery systems have been depleted and are not available.o The plant was in Shutdown Cooling until the station blackout and has since been slowlyrepressurizing due to heating up.o Current RPV pressure is 75 psig-and slowly rising.o H SRV has failed to reseat and indication of the tailpipe vacuum breaker sticking open have led toa Drywell pressure of 45 psig and rising about 1 psig every 30 minutes.o Efforts to align the diesel fire pump to DW sprays have been unsuccessful due to the flooding.o The TSC has recommended venting the DW by using the Hard Pipe Vent using procedure A.8-05.08, Manually Open Containment Vent LinesINITIATING CUES (IF APPLICABLE):o The CRS directs operator to initiate DW venting through the Hard Pipe Vent lAW procedure A.8-05.08, Manually Open Containment Vent Lines, Parts A and B.Revision 2Page A-20 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSHard Pipe Vent local manual operation Job Performance Measure entry condition assumptions,Information excerpted from Hughes Associates Record of Correspondence, Hard Pipe Vent ManualOperation e-mails with Xcel Energy during June 2013, Hughes Associates, Baltimore, MD, 7 July 2013:Conditions anticipated following a SBO resulting from an external flooding event:o ERO has been manned for the past several days, with these procedures predicted and plannedto be implemented ahead of timeo Plant is in cold shutdown condition (mode 4)o Operations staffing to perform the procedures would be optimal (several operators assigned asdesired to each procedure)o Environment would be consistent with SBO (hot, dark, damp)o There would be more than 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months to perform the procedures, allowing several opportunities totroubleshoot and/or re-perform steps if necessaryo The ERO would place maximum priority on maximizing chances of successful performance ofthese proceduresOperator Interview Insights:The JPM that was completed by Xcel with 2 ROs and 2 NLOs was JPM A.8-05.08-001, Rev. 0, ManuallyOpen Containment Vent Lines. The average time to complete the JPM was 30 minutes given theinformation that the N2 bottles were staged on the CRD catwalk. There were no problems or issues thatrequired any of the operators to stop and get clarifying information, it was identified that removing fittingswas not the best idea it would be better if the lines had tee's installed where the caps could be removedand the appropriate lines connected. This way the capped connection could be labeled to furtherminimize connecting to the wrong fitting. The operators stated that strips of non-skid should be placed onthe areas around the site for safety reasons. They also mentioned using the LED headlights versusflashlights to allow both hands to be free.Manpower Requirements: ..._....._.____"_Ci~Wei~ier hclu~de~d:: TotaAIIVailale 4KRqiiiredfr 'Noe____________ Ex'c~itip'"in _ _ _ __ _Reactor operators Yes 2 1Plant operators Yes 2 0Mechanics Yes 2 0Electricians Yes 2 0I&C Technicians Yes 2 0Health Physics Technicians Yes 2 0Chemistry Technicians Yes 1 0Execution Performance Shapina Factors:Environment: Lighting PortableHeat/Humidity Hot / HumidRadiation BackgroundAtmosphere Steam (although steam will notbe present, this PSF was usedto indicate an off-normalcondition, such as would bepresent for flood and SBO)Special Requirements: Tools RequiredAdequateAvailableParts RequiredI I_ AdequateRevision 2Page A-21 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSClothing RequiredAdequateComplexity of Response: Cognitive ComplexExecution ComplexEquipment Accessibility Main Control Room Accessible(Cognitive):Equipment Accessibility Reactor Building With Difficulty(Execution):Stress: HighPlant Response As Expected: YesWorkload: HighI Performance Shaping Factors: NegativePerformance Shaping Factor Notes:The response is considered to be Complex due to the flooding and SBO impacts to lighting andaccessibility. Flashlights, headlamps and boots were considered necessary by Training when the JPMswere performed for these tasks.The Equipment Accessibility is evaluated as With Difficulty due to Rx building lighting and flooding issues.Key Assumptions (see that section) regarding the conditions provided to Training for performing the JPMfor this task said that the "Environment would be consistent with SBO (hot, dark, damp)". The Traininginsights from the JPM performance stated that the operators recommended the use of "LED headlightsversus flashlights", so it is clear that portable lighting is used.Despite preparations and training, the flooding scenario is considered to be a high stress situation.The steps identified as Critical in JPM-A.8-05.08-001 were used for the Execution quantification.Timing:T SW15.00 HoursT 5.50 HoursdelayT1/2 10.00 MinutesTM 45.00 MinutesM ~ I1CueIIrreversibleDamageStateI-I.t=0Timing Analysis:TO = Station Blackout.Tsw = Per MAAP run Rcic-dgl 3-cts-ABS performed in support of an external flooding SDP, containmentpressure reaches 56 psig at 14 hours1.62037e-4 days 0.00389 hours 2.314815e-5 weeks 5.327e-6 months following a SBO (flooding >930'). Core temperature reaches 1800degrees F at 15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months due to CST depletion and no transfer of RCIC to the torus. This is conservativetiming as refilling of the CST is very likely.Td = 5.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months -Based on an interview conducted in a prior analysis with a senior Shift Manager, theorder to begin the procedure to manually operate the hard pipe vent would be given at approximately 27psig containment pressure. This is due to the step in C.5-1200 (DW/Torus Pressure leg) that says if youcannot restore and maintain drywell pressure within Figure 0 (27psig for 0 ft torus level), then maintaindrywell pressure less than Figure D (56 psig).The 5.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months is based on MAAP run Rcic-dg13-cts-ABS as the time when drywell pressure reaches 42psia (27 psig) [Worksheet d43-1, column AC Drywell Pressure]T1/2 = According to the initial conditions assumed by Training for the Job Performance Measureperformed for this task, the ERO will have been manned for the past several days, with these proceduresRevision 2Page A-22 1 SML16012.000-1Appendix A -HRA CALCULATOR REPORTSpredicted and planned to be implemented ahead of time. Daily planning meetings will have been held todiscuss actions to be taken, so the 10 minutes is simply an estimate of the meeting time between TSCand ERF personnel to make the actual decision to vent the DW by using the Hard Pipe Vent. The controlroom supervisor (CRS) will then direct operators to initiate the process.Tm = Results of HPV local manual operation Job Performance Measure A.8-05.08-001 performed 18June 2013. The procedure was performed four times, taking an average of 30 minutes. Additional 15minutes for C.5-3505-A steps 3 and 4.Time available for cognition and recovery: 525.00 MinutesTime available for recovery: 515.00 MinutesSPAR-H Available time (cognitive): 525.00 MinutesSPAR-H Available time (execution) ratio: 12.44Minimum level of dependence for recovery: ZDRevision 2Page A-23 1SMLII16012.000-1Appendix A -HRA CALCULATOR REPORTSCognitive UnrecoveredHPVSBOFLOODTable 47: HPVSBOFLOOD COGNITIVE UNRECOVERED:Pc Failure .Mecdhanism ... -". 1 .1 ." 1 1 .Branch : .HEP.::..Pca: Availability of Information d 1.5e-03PCb: Failure of Attention m 1.5e-02Pcc: Misread/miscommunicate data e 3.0e-03Pcd: Information misleading b 3.0e-03Pce: Skip a step in procedure e 2.0e-03Pcf: Misinterpret instruction a neg.Pcg: Misinterpret decision logic c 6.0e-03PCh: Deliberate violation a neg.Sum of Pca through PCh = Initial Pc = 3.1e-02Notes:Presumed that SBO causes issues with normal alarms and indications so pc-a through -d were adjustedconsistent with insights from EPRI 1025294, A Preliminary Approach to Human Reliability Analysis forExtemal Events with a Focus on Seismic, October 2012.Revision 2 Page A-24Revision 2Page A-24 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSpca: Avlabhty of infonnationIndiation ail in CR Indication bminglAlftmate Training onCR Accurate in Procedure IndcatorsI.0e-01 (a) neg..Oe.00 1.0e+00 (b) neg.O.0e4.00 I .oe-o (c) neg-7- e0(d) 1-pe-03Yes 5.0e-0 (e) 5.0e-02No1.e+00 f) 5.oe-o01.0e+001.0e-+O (g) .0" WOMCR indications may not be accurate due to the Station Blackout, however, either procedural or informalcrew information on alternate indications and training should provide operator input to decision-making.pcrb: Failure of attentionLow vs. Hi Check vs. Monitor Front vs. Back Aarmed vs.NotWokdload Panel AlarmedEvout(a) neg-O.Oe0 Back .0(b) 1.5e-4LOW 3.0e-03 (c) 3.0e-031.0e+001.0e+00 Front 5e-2(d) 1.-%-045.0e-02OMonitor I0-0e+00 l(e) 3.0e-033.0e-03 Back 5.0e-02 (f) 3.0e-041. Nice 3.0e-03 1(g) 6.0e-032. ic Fro,,t 15.,10 (h eg-5(b0n-02Check O.Oe+0 18 0(i) neg.0.0e*WBack (.0e.so5.0e-02e-04WIgh 3.0e-03 1Ae(k) 1.e-02Front ()7.5e-04Monitor --- Oe --0- (m) I.5e-023 -Back 50e-02 (n) 1.5e-033.Oe-03 I1.0e0 (o) 3.0e-02Revision 2 Page A-25Revision 2Page A-25 I SM L16012.000-1Appendix A -HRA CALCULATOR REPORTSISM LI 6012.000-1 Appendix A -HRA CALCULATOR REPORTSpcc: Misreadftniscmmnnicate dataInhicators Easy to Good--ad Indicator Fom- --Locate cminunicafionsI O.Oe.H) (a) neg.O.Oe.)O 3i 3 (b) 3.0e-03, O-Oe+0 (c) 1.0e-030(g) 4.0e-031.0e-03 (h) 4.0e-033.0e-03o.oe-4oo (g) 3.Oe-0313.0e-033.oe-o3 (h) 7.Oe-O3pcd: Infonmtion fidNilngM Cuesas Stated Warnng SpecoTc Tbn,,ig e TiningDire IIo.oe+0o (a) meg.No-------------------- -------------- --------(b) 3Je-03.0-L-02 (c) 1.0e-021..eOe0 1..od-o (d) 1.Oe-O11.Oe+OO (e) 1.0e" 0MCR indications may not be accurate due to the Station Blackout so cues may not be as stated inprocedures.pce: Sli a step in procedureObvious Ms Eing s Mlle V& MUPleawaf cekeqing A&d13.Oe-O3(a) 1 .0e-033.3e-01 (b) 3.Oe-031.0e.-02O.e.O0 3(c) 3.0e-03.Oe.001e-0 (d) 1.8e-02-(e) 4-e-033.3e-o------.----Yes3.0e-03 13.e-3 (g) 6.0e-031.Oe4-OI (h) I.3e-021..0e-021.0e-01 (i) t.0e -0tRevision 2 Page A-26Revision 2Page A-26 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSI SMLI 6012.000-1 Appendix A -HRA CALCULATOR REPORTSpf: Misinterpret instructionStandard or AM Required 7haning on StepAmbiguous wonling Information--- ------- ------- --------- --- (a) neg.(b) 3.oe-033.0e-02 (c) 3.0e-02NO .0e4H (d) 3.0e-03o.e-,.o I(e) 3.0e-023.0e-02 1.0e-01 (f) 6.Oe-033.0e..02 I 0 (g) 6.0e-02pcg: Mi§sinrmpt decision ogicNMor statemmut -ir*N or -ow- Both AND' & IPracticed ScenailStatement "OFr3.3e41 (a) 1.Ge-023.0e-02 (b) 4.9--021.2-02 -3(c) 6.0e-0333.ie-Ol-.Oe. (d) .9e-026.0e-03 (1.0e.9.423.3e-1 (e) 2.0e-03O.Oe-Oe-0Yes OO + 1.00,6 0O (f) 6.0e-03(g) t.Oe-02No 3.0e-02 --(h) 3.1e-021.0e30.-0I.0e-03 30"1 3.0e-0M13.3e-01 (k) neg.O.OedO l- (1) neg.pch: Deliberate violationBelef in Adequacy Adverse Reasonable Poky ofof Instructon Consequence if Alternatis "'Verbatic"oew------- --- ------- ------- --------- ------- ------ (a) neg.Yes 5.0eM (b) 5.0"-01oI. (c) 1.0e4WI.Oe4O110e00 O.Oe,.O0 (d) neg.Io.oe.,o (e) neg.Revision 2 Page A-27Revision 2Page A-27 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSI SMLI 6012.000-1 Appendix A -HRA CALCULATOR REPORTSCognitive RecoveryHPVSBOFLOODTable 48: HPVSBOFLOOD COGNITIVE RECOVERY< a) (" I- LL '.D FinalInitiaIIl. HE > Z 1 -'5: -r-.O Value0CO W nOa C -O) Lu ValuePc. 1.5e-03 X X -2.5e-01 3.8e-04Pcb: 1.5e-02 X X X MD 3.8e-03 5.7e-05Pc': 3.0e-03 X X MD 2.1e-02 6.3e-05PCd: 3.0e-03 X X X MD 7.3e-03 2.2e-05<PCe: 2.0e-03 X X X MD 1.0e-02 2.0e-05, :; neg. -1.0e+00P. 6.e-03 X X X MD 1.1 e-02 6.6e-05-I--neg. 1.0e+00P 6 SuoP dt 6.1e-04Notes:Due to long timeframe and severity of scenario, STA and Emergency Response Facility will be available.Operations staffing to perform the procedures was assessed by Xcel as optimal (several operatorsassigned as desired to each procedure) so Extra Crew was credited.Used Moderate Dependency due to high stress.Revision 2 Page A-28Revision 2Page A-28 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSISM LI 6012.000-1 Appendix A -HRA CALCULATOR REPORTSExecution UnrecoveredHPVSBOFLOODTable 49: HPVSBOFLOOD EXECUTION UNRECOVEREDProcedurYe C:A8-5.08,eManuallyOpen Containm ent CvehtLines ., omment Stress Over RideI IStep.No.* jnstructionlComnent,-, Error' -,. HTHERP HEP Factor.,Type' Table Item -..___- _Connect and apply pressure from AH-1 cylinder to rupture Rupture DiskPSD-4543A.8-05.08, Step 4 Location: Reactor Building EOM 20-7b 2 1.3e-03EOC 20-12 5 1.3E-3Total Step HEP 1.3e-02Connect and adjust AH-1 regulator to less than 100 psig and slowly openAH-1 discharge valve to open valve AO-4539 5A.8-05.08, Step 5 Location: Reactor Building EOM 20-7b 4 4.3e-03EOC 20-13 5 1.3E-2Total Step HEP 8.7e-02Connect and adjust AH-2 regulator to less than 100 psig and slowly openAH-2 discharge valve to fully open valve AO-4540 5A.8-05.08, Step 6 Location: Reactor Building EOM 20-7b 4 4.3e-03EOC 20-13 5 1.3E-2 ITotal Step HEP 8.7e-02Open and Close the HPV isolation valves as directed by shift supervisorC.5-3505 Part A, Location: Reactor Building EOM 20-7b 1 4.3e-04 5Step 3 1 EOC 20-13 2 3.8E-3 ITotal Step HEP 2.1e-02Monitor Containment Pressure and Radiation Levels in the Hard PipeC.5-3505 Part A Vent. 5Step 4 Location: Reactor Building EOM 20-7b 1 4.3e-04Step 4 EOC 20-10 1 3.8E-3Total Step HEP 2.1e-02Feedback from Control Room 5Recovery Location: Main Control Room EOM 20-7b 3 1.3e-03 ITotal Step HEP 6.5e-03Revision 2 Page A-29Revision 2Page A-29 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSExecution RecoveryHPV_SBOFLOODTable 4-10: HPVSBOFLOOD EXECUTION RECOVERYc it.Recovery Step No.. -i HEP (crit)i HEP'Rec .Dep. P"Cond. :.Totalffor.~Criticalý 'te k o .__________ _______________________________________________________....___.... ..._(Rec) StepA.8-05.08, Step 4 Connect and apply pressure from AH-1 cylinder to rupture 1.3e-02 7.3e-04Rupture Disk PSD-4543Recovery Feedback from Control Room 6.5e-03 LD 5.6e-02A.8-05.08, Step 5 Connect and adjust AH-1 regulator to less than 100 psig andslowly open AH-1 discharge valve to open valve AO-4539 8.7e-02 4.9e-03Recovery Feedback from Control Room 6.5e-03 LD 5.6e-02A.8-05.08, Step 6 Connect and adjust AH-2 regulator to less than 100 pslg and 8.7e-02 4.9e-03slowly open AH-2 discharge valve to fully open valve AO-4540Recovery Feedback from Control Room 6.5e-03 LD 5.6e-02C.5-3505 Part A, Open and Close the HPV isolation valves as directed by shift 2.1 e-02 1.2e-03Step 3 supervisorRecovery Feedback from Control Room 6.5e-03 LD 5.6e-02C.5-3505 Part A, Monitor Containment Pressure and Radiation Levels in the 2.1 e-02 1.2e-03Step 4 1 Hard Pipe Vent.I Recovery Feedback from Control Room 6.5e-03 LD 5.6e-02-* .: .Total ....I.- Unrecoered:- 2.3e1- .Total R 2ovIered: 1.3e2Revision 2 Page A-30Revision 2Page A-30 ISML16012.000-1Appendix A -HRA CALCULATOR REPORTSA.3. RCICSBOFLOOD, Fail to manually operate RCIC during SBO and extremeflooding conditions (SPAR-H)Basic Event Summary'Planlt;:".. i. Data :File Dati e ;:: Rebo d ::".Monticello Ext 909312 07/02/13 07/02/13Flooding SDPHRAJune2013_SPAR Hquant forsensitivity.HRATable 11: RCIC_SBOFLOOD SUMMARY[Ana l, i Resu!ts:.-I4 Cognitive Execution[Failor 3.2e.. 9.1 e-021 .4e-01Plant:MonticelloInitiating Event:External Flood + SBOBasic Event Context:The flooding engineer provides daily updates to the station on high river water levels including potentialsto rise above any A.6 trigger points. At this point, heightened awareness of the potential for flooding isimplemented.When river level exceeds 921 feet an evaluation of EALs would be performed. If visible damage hasoccurred due to flood water rising greater than 921 feet, then an Alert per EAL HA1.6 would be declared.Prior to river levels reaching these levels, operators would be walking down the A.8 procedures foralternate methods to vent primary containment and operate RCIC remotely. This would involve staging ofequipment in the torus area to open the Hard Pipe Vent and verification that equipment is properly stagedto operate RCIC remotely.EDGs and batteries are not available. Shutdown cooling, HPCI, and RCIC are not available from normalelectrical means. RCIC is available for manual operation.Operators have temporary level indication setup in the reactor building. Pressure indication is available inthe direct area of the level transmitters. The building is dark and most likely water in the basement of thereactor building. Additional portable lights are available to assist with lighting and boots staged for higherwater. The operators would utilize A.8-05.01 to un-latch the governor from the remote servo linkage andthrottle steam flow to RCIC to start the turbine rolling while coordinating with operators monitoring waterlevel and reactor pressure. Upon reaching the high end of the level band the operators would throttleclosed the steam admission valve and await direction to re-start RCIC. Local operation of RCIC isdemonstrated each refueling outage during the over speed test. Operation of a coupled turbine run isless complex because the turbine is easier to control with a load.Revision 2Page A-31 ISML16012.000-1Appendix A -HRA CALCULATOR REPORTSTiming:T 7.97 HoursT delay 5.75 Hours i T1/2 10.00 Minutes TM 80.00 Minutes1IrreversibleCue DamageStatet=oTiming Analysis: TO = Station BlackoutTsw = Time from Station Blackout to the time by which RCIC must be restored.Per Monticello MAAP Calculations, case "SBOCase3-RI", 27 June 2013:Time to TAF = 7.17 hrsTime to -149" = 7.2 hrsTime to 1800 F = 7.97 hrsDamage is assumed to occur if the temperature exceeds 1800 F or 7.97 hrs, so this was used as the timeby which RCIC restoration is required.Tdelay = PRA battery calc (PRA-CALC-1 1-002) indicates that there are 5.75 hrs until RCIC batterydepletion. Also, the RCIC Water Flow (column BC) of the d41 tabs in the "SBOCase3-RI" MAAPanalysis spreadsheet shows that RCIC injection stops at approximately the same time (5.74 hrs), so theMAAP runs agree with the calc. This Tdelay can be considered somewhat conservative, since in reality, itis likely that an action would be taken before waiting for battery depletion.T1/2 = The cue for action is that the TSC and the Emergency Response Director have determined thatRCIC operation is needed. Daily planning meetings will have been held to discuss actions to be taken assoon as the diesels are lost, so the 10 minutes is simply an estimate of the meeting time between TSCand ERF personnel to make the actual decision to manually operate RCIC. The Control Room Supervisor(CRS) directs operator to initiate RCIC and inject into the RPV using procedure A.8-05.01, ManualOperation of RCIC, Part A, Placing RCIC in Service.Tm = Results of RCIC local manual operation Job Performance Measure performed 18 June 2013. Theprocedure was performed three times, taking 49 minutes, 37 minutes and 50 minutes to complete for anaverage time of 45 minutes. 50 minutes was used as the conservative value for JPM performance.The JPM did not include the performance of Part B for installation and use of the Fluke level monitoringdevice; this was estimated to require 30 minutes, so the total time for Tm was estimated as 50 min + 30min = 80 min.Time available for recovery: 43.20 MinutesSPAR-H Available time (cognitive): 53.20 MinutesSPAR-H Available time (execution) ratio: 1.54Minimum level of dependence for recovery: LDRevision 2 Page A-32Revision 2Page A-32 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSISMLI6OI2.000.1 Appendix A -HRA CALCULATOR REPORTSPART I. DIAGNOSISPSFss PSF ,ve;s9 %fMultlper~or<.Available Time Inadequate Time P(failure) = 1.0(recommended choice Barely adequate time (~ 2/3 x nominal) 10based on timing Nominal time 1information in bold) Extra time (between 1 and 2 x nominal 0.1and > 30 min)Expansive time (> 2 x nominal and > 30 X 0.01min)Insufficient Information IStress Extreme 5High X 2Nominal 1Insufficient Information IComplexity Highly complex 5Moderately complex X 2Nominal 1Obvious diagnosis 0.1Insufficient Information 1Experience/Training Low 10Nominal X 1High 0.5Insufficient Information 1Procedures Not available 50Incomplete 20Available, but poor 5Nominal X 1Diagnostic/symptom oriented 0.5Insufficient Information 1ErgonomicslHMI Missing/MisleadingJ 50Poor 10Nominal X IGood 0.5Insufficient Information 1Fitness for Duty Unfit P(failure) = 1.0Degraded Fitness 5Nominal X 1Insufficient Information 1Work Processes Poor 2Nominal 1Good X 0.8Insufficient Information 1Revision 2 Page A-33Revision 2Page A-33 ISM LI6012.000-1ApndxA-HACLUTORERSAppendix A -HRA CALCULATOR REPORTSDiagnosis HEP:3.2e-04PART I1. ACTIONPSFs PSF IUVeis. ~ Multi 11ýr for.__________________ griagn sisAvailable Time Inadequate Time P(failure) = 1.0(recommended choice Time available is -the time required 10based on timing Nominal time X 1information in bold) Time available >= 5x the time required 0.1Time available >= 50x the time required 0.01Insufficient Information 1Stress/Stressors Extreme 5High X 2Nominal 1Insufficient Information 1Complexity Highly complex 5Moderately complex X 2Nominal 1Insufficient Information 1Experience/Training Low 3Nominal X 1High 0.5Insufficient Information 1Procedures Not available 50Incomplete 20Available, but poor X 5Nominal 1Insufficient Information 1Ergonomics/HMI Missing/Misleading 50Poor X 10Nominal 1Good 0.5Insufficient Information 1Fitness for Duty Unfit P(failure) = 1.0Degraded Fitness 5Nominal X 1Insufficient Information 1Work Processes Poor 5Nominal 1Good X 0.5Insufficient Information 0.5Revision 2 Page A-34Revision 2Page A-34 ISML16012.000-1 Appendix A -HRA CALCULATOR REPORTSAction Probability:9.1e-02 [Adjustment applied: 1.0e-3 * 1.0e+02 / (1.0e-3 * (1.0e+02 -1) + 1)]PART Ill. DEPENDENCYcaeI Im In~ mC..-mhwamccwiTask Failure WITHOUT Formal Dependence:9.1le-02Task Failure WITH Formal Dependence:1 .4e-01Revision 2 Page A-35Revision 2Page A-35 ISML16012.000-1Appendix A -HRA CALCULATOR REPORTSA.4. HPVSBOFLOOD, Fail to operate the HPV using N2 bottles to providecontainment heat removal during SBO/Flood (SPAR-H)Basic Event Summary.:Plant , :Datale FileSize".. * FileDate : Rerd DateMonticello Ext 901120 06/28/13 06/28/13Flooding SDPHRAJune2013-SPAR Hquant for1 sensitivity.HRAJohn Spaargaren & PierreMacheret, Hughes AssociatesTable 412: HPVSBOFLOOD SUMMARYAnalyssResults-,* Cognitive ExecutionFe ! rN r 1b6 1i.ii 3.2e-04 5.0e-03Total :HEP. I 5.5e-02Plant:MonticelloInitiating Event:External Flood + SBOBasic Event Context:The flooding engineer provides daily updates to the station on high river water levels including potentialsto rise above any A.6 trigger points. At this point, heightened awareness of the potential for flooding isimplemented.When river level exceeds 921 feet an evaluation of EALs would be performed. If visible damage hasoccurred due to flood water rising greater than 921 feet, then an Alert per EAL HA1.6 would be declared.Prior to river levels reaching these levels, operators would be walking down the A.8 procedures foralternate methods to vent primary containment and operate RCIC remotely. This would involve staging ofequipment in the torus area to open the Hard Pipe Vent and verification that equipment is properly stagedto operate RCIC remotely.EDGs and batteries are not available. Shutdown cooling, HPCI, and RCIC are not available from normalelectrical means. RCIC is available for manual operation.Revision 2 Page A-36Revision 2Page A-36 1SML16012.000-1 Appendix A -HRA CALCULATOR REPORTSTimina:T S 15.00 HoursTdelay 5.50 Hours T1/2 10.00 Minutes TM 45.00 MinutesIreversibleCue DamageStatet=oAnalysis: TO = Station Blackout.Tsw = Per MAAP run Rcic-dg13-cts-ABS performed in support of an external flooding SDP, containmentpressure reaches 56 psig at 14 hours1.62037e-4 days 0.00389 hours 2.314815e-5 weeks 5.327e-6 months following a SBO (flooding >930'). Core temperature reaches 1800degrees F at 15 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months due to CST depletion and no transfer of RCIC to the torus. This is conservativetiming as refilling of the CST is very likely.Td = 5.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months -Based on an interview conducted in a prior analysis with a senior Shift Manager, theorder to begin the procedure to manually operate the hard pipe vent would be given at approximately 27psig containment pressure. This is due to the step in C.5-1200 (DW/Torus Pressure leg) that says if youcannot restore and maintain drywell pressure within Figure 0 (27psig for 0 ft torus level), then maintaindrywell pressure less than Figure D (56 psig).The 5.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months is based on MAAP run Rcic-dg13-cts-ABS as the time when drywell pressure reaches 42psia (27 psig) [Worksheet d43-1, column AC Drywell Pressure]T1/2 = According to the initial conditions assumed by Training for the Job Performance Measureperformed for this task, the ERO will have been manned for the past several days, with these procedurespredicted and planned to be implemented ahead of time. Daily planning meetings will have been held todiscuss actions to be taken, so the 10 minutes is simply an estimate of the meeting time between TSCand ERF personnel to make the actual decision to vent the DW by using the Hard Pipe Vent. The controlroom supervisor (CRS) will then direct operators to initiate the process.Tm = Results of HPV local manual operation Job Performance Measure A.8-05.08-001 performed 18June 2013. The procedure was performed four times, taking an average of 30 minutes. Additional 15minutes for C.5-3505-A steps 3 and 4.Time available for recovery: 515.00 MinutesSPAR-H Available time (cognitive): 525.00 MinutesSPAR-H Available time (execution) ratio: 12.44Minimum level of dependence for recovery: ZDRevision 2 Page A-37Revision 2Page A-37 1SML16012.000-1Appendix A -HRA CALCULATOR REPORTSPART I. DIAGNOSISP PSFs,6V , AfPSF vels u-ti'for-Dagposis,Available Time Inadequate Time P(failure) = 1.0(recommended choice Barely adequate time (~ 2/3 x nominal) 10based on timing Nominal time 1information in bold) Extra time (between 1 and 2 x nominal 0.1and > 30 min)Expansive time (> 2 x nominal and > 30 X 0.01min)Insufficient InformationStress Extreme 5High X 2Nominal 1Insufficient Information 1Complexity Highly complex 5Moderately complex X 2Nominal 1Obvious diagnosis 0.1Insufficient Information 1Experience/Training Low 10Nominal X 1High 0.5Insufficient Information 1Procedures Not available 50Incomplete 20Available, but poor 5Nominal X 1Diagnostic/symptom oriented 0.5Insufficient Information 1Ergonomics/HMI Missing/Misleading 50Poor 10Nominal X 1Good 0.5Insufficient Information 1Fitness for Duty Unfit P(failure) = 1.0Degraded Fitness 5Nominal X 1Insufficient Information 1Work Processes Poor 2Nominal 1Good X 0.8Insufficient Information 1Revision 2 Page A-38Revision 2Page A-38 1 SML-16012.000-IAppendix A -HRA CALCULATOR REPORTSI SMLI 6012.000-1 Appendix A -HRA CALCULATOR REPORTSDiagnosis HEP:3.2e-04PART II. ACTION.PSFs,, PSFLevels' s Multiplier forS~ DiagflosisAvailable Time Inadequate Time P(failure) = 1.0(recommended choice Time available is -the time required 10based on timing Nominal time X 1information in bold) Time available >= 5x the time required 0.1Time available >= 50x the time required 0.01Insufficient Information 1Stress/Stressors Extreme 5High X 2Nominal 1Insufficient Information 1Complexity Highly complex 5Moderately complex 2Nominal X IInsufficient Information 1Experience/Training Low 3Nominal 1High X 0.5Insufficient Information 1Procedures Not available 50Incomplete 20Available, but poor 5Nominal X 1Insufficient Information 1Ergonomics/HMI Missing/Misleading 50Poor X 10Nominal 1Good 0.5Insufficient Information IFitness for Duty Unfit P =failure) 1.0Degraded Fitness 5Nominal X 1Insufficient Information 1Work Processes Poor 5Nominal 1Good X 0.5Insufficient Information 0.5Action Probability:5.0e-03Revision 2 Page A-39Revision 2Page A-39 ISMLI16012.000-1 Appendix A -HRA CALCULATOR REPORTSPART II1. DEPENDENCYC,=, TD I E I I C ,F.-- -Cb ntin i...,=, ,w M&IMAB ~ F, ibTask. Failre WTHOUForal D endncesocb addiiorW khedlafr-I.-ks. &k*T Faaulia u HD5emTask Failure WITHOUT Formal Dependence:5.3e-03Task Failure WITH Formal Dependence:5.5e-02Revision 2 Page A-40Revision 2Page A-40'

ISML16012.000-1B. APPENDIX B -EVENT TREESAppendix B -EVENT TREESRevision 2 Page B-IRevision 2Page B-1 EXTERNAL FLOOD >930' < 935' EARLY WARNING REACTOR BUILDING PROTECTED RCIC/RPV & HARD PIPE VENT Prob NameSUCCESSFUL EARLY WARNINGO.OOE+00FLOOD <935'0.891RCIC SUCCESS0.894EXTERNAL FLOOD >930'[8.90E-06][1]SUCCESSFUL EARLY WARNING[0.106]O.00E+007.09E-068.41 E-070.OOE+007.72E-070.15E-081 07F-07DKOK'D Seq 1:)KDK,D Seq 2MD Seq 3O.00E+00FLOOD > 935'[0.109]RCIC SUCCESSREACTOR BLDG PROTECTED0.8940.89FAILURE TO PROTECT RB[0.106]1lI[0.11]IMonticello, Flood SDP 930-935.eta17/3/2013 1 Page 1IMonticello Flood SDP 930-935.eta 7/3/2013 Page 1 EXTERNAL FLOOD >930' < 935' EARLY WARNING REACTOR BUILDING PROTECTED RCIC/RPV & HARD PIPE VENT Prob I NameSUCCESSFUL EARLY WARNINGO.OOE+00FLOOD <935'0.5in flflF4flfRCIC SUCCESS1 a; mai--fnr,[1]0.894'I .uhlt--ubEXTERNAL FLOOD >930'[2.00E-05][0.106]SUCCESSFUL EARLY WARNING:)K::)K,D Seq 1:)K,D Seq 2'D Seq 3O.00E÷00FLOOD > 935'[0.5]RCIC SUCCESSREACTOR BLDG PROTECTED0.8940.89FAILURE TO PROTECT RB7.96E-06-9.43E-071.10E-06[0.106][1][0.11]Monticello Flood SDP 930-935 Sens Freq.eta17/3/2013 1 Page 1 EXTERNAL FLOOD >930' < 935' EARLY WARNING REACTOR BUILDING PROTECTED RCIC/RPV & HARD PIPE VENT Prob NameSUCCESSFUL EARLY WARNINGIO.OOE+00FLOOD <935'0.891 1RCIC SUCCESS0.805D.O0E+005.38E-061.55E-06EXTERNAL FLOOD >930'[8.90E-06][1]SUCCESSFUL EARLY WARNING[0.195]ILl=t =IPI Jt I:)K:)K,D Seq 1:)K:)K'D Seq 2'D Seq 30.OOE+00RCIC SUCCESSFLOOD > 935'[0.109]REACTOR BLDG PROTECTED0.805[1]0.89] FAILURE TO PROTECT RB[0.195]5.95E-071 .68E-071.07E-07[0.11]Monticello Flood SDP 930-935 Sens SPAR-H.eta 7/3/2013 Page 1 Enclosure 3Monticello Nuclear Generating Plant"Monticello Flood Protection"11 Pages Follow Monticello Flood Protection1.0 PURPOSEThe purpose of this document is to evaluate the flood protection provided at MonticelloNuclear Generating Plant (MNGP).Nuclear power plants are designed to meet robust design criteria, referred to as GeneralDesign Criteria (GDC); which are now codified as part of NRC regulations in 10 CFRPart 50. The GDC have existed in various forms prior to being codified in part 50 andplant commitments to meet the GDC (or pre-existing requirements) depend on the ageof the plant.MNGP was designed before the publishing of the 70 General Design Criteria (GDC) forNuclear Power Plant Construction Permits proposed by the Atomic Energy Commission(AEC) for public comment in July 1967, and constructed prior to the 1971 publication ofthe 10 CFR 50, Appendix A, GDC. As such, MNGP was not licensed to 10 CFR 50Appendix A, GDC. The MNGP USAR, Section 1.2, lists the Principal Design Criteria(PDC) for the design, construction and operation of the plant. MNGP USAR Appendix Eprovides a plant comparative evaluation to the 70 proposed AEC design criteria. It wasconcluded in the USAR that the plant conforms to the intent of the GDC. A listing of thePDC and AEC GDC (by number and title) pertaining to external flooding is providedbelow:PDC 1.2.1 .c "General Criteria""The design of those components which are important to the safety of the plantincludes allowances for the appropriate environmental phenomena at the site.Those components important to safety and required to operate during accidentconditions are designed to operate in the post accident environment."AEC Criterion 2 -Performance Standards (Category A)"Those systems and components of reactor facilities which are essential toprevention of accidents which could affect the public health and safety or tomitigation to their consequences shall be designed, fabricated, and erected toperformance standards that will enable the facility to withstand, without loss ofthe capability to protect the public, the additional forces that might be imposed bynatural phenomena such as earthquakes, tornadoes, flooding conditions, winds,ice, and other local site effects. The design bases so established shall reflect: (a)appropriate consideration of the most severe of these natural phenomena thathave been recorded for the site and surrounding area and (b) an appropriatemargin for withstanding forces greater than those recorded to reflectuncertainties about the historical data and their suitability as a basis for design."This evaluation addresses the following aspects of flood protection that are provided forthe MNGP to meet AEC Criterion 2:* Flood Analyses -this discussion describes the site location, hydrology anddetermination of the maximum predicted flood water elevations and timing.Page 1 of 11

Flood Mitigation Strategy -this discussion describes the aspects provided topreclude the design bases flood from adversely impacting the site. Thisprotection is provided by structural design and procedural actions.* Flood Protection Implementation -this discussion describes the actions taken atthe site to provide reasonable assurance that flood protection strategy can beeffectively implemented in a design bases flood scenario.2.0 FLOOD ANALYSISThis section describes the site location and hydrology, and a summary of current designbasis flood elevations. Information in this section is based on information in the MNGPUpdated Safety Analysis Report (USAR) (Reference 1); specific sections are identifiedbelow.2.1 Site Location and DescriptionThe plant is located within the city limits of Monticello, Minnesota on the right (west)bank of the Mississippi River. The topography of the MNGP site is characterized byrelatively level bluffs which rise sharply above the river. Three distinct bluffs exist at theplant site at elevations 920, 930, and 940 ft. above msl. The finished plant grade isapproximately 930 ft. msl. The plant grade surrounding Class I and Class II structureshousing Class I equipment varies between 935 ft. msl and 930 ft. msl. The sitedescription and topography is described in detail in the MNGP USAR, Section 2.2.HydrologyThe Mississippi River is the major hydrologic feature for the site. The river poses thesignificant flooding source for the site. Table 1, below, summarizes normal and floodedriver flow rates and water elevations.Table 1Normal and Flooded River Flow Rates and Water ElevationsMississippi River Flow Rate (cfs) Water ElevationCondition (ft. msl)Normal 4,600 905Maximum Recorded(1965) 51,000 9161000 Year Flood -90,000 (1) 921Probable Maximum 364,900 939.2Flood 364,900 _ 939.2(1) Estimated using USAR Appendix G, Exhibit 8, for a waterelevation of 921 ft.Normal river level at the MNGP site is about 905 ft. msl at a distance 1.5 milesupstream, the normal river elevation is about 910 ft. msl and at an equal distancedownstream, the river is at 900 ft. msl. The following flow statistics are estimated for theMississippi River at the MNGP site:Page 2 of 11 Average Flow -4,600 cubic feet per second (cfs)Minimum Flow -240 cfsMaximum Flow -51,000 cfsThe maximum reported high water level at the MNGP site was about 916 ft. msl whichwas recorded during the spring flood of 1965 with an estimated river flow of 51,000 cfs.The results of flood frequency study for the 1000 year flood estimated a peak stage of921 ft. msl (USAR Section 2.4)2.2 Design Basis Flood HazardThe following flood scenarios are evaluated as part of the MNGP licensing basis [USARAppendix G]:* Flooding in Streams and Rivers* Flooding due to Downstream Ice Dam Build-UpA summary of the results as described in Reference 2 for each of these floodingscenarios is provided below; specific sections from Reference 2 are identified with theassociated discussion.2.2.1 Flooding in Streams and RiversThe probable maximum discharge was determined to be 364,900 cfs and acorresponding peak stage of elevation 939.2 ft. msl. The flood would result frommeteorological conditions which could occur in the spring and would reach maximumriver level in about 12 days. It was estimated the flood stage would remain aboveelevation 930.0 ft. msl for approximately 11 days.The most critical sequence of events leading to a major flood would be to have anunusually heavy spring snowfall and low temperatures after a period of intermittent warmspells and sub-freezing temperatures has formed an impervious ground surface andthen a period of extremely high temperatures followed by a major storm. The snowmeltand rainfall excesses were then routed to the plant site by computer modeling. A stagedischarge rating curve was then constructed. The probable maximum discharge wasdetermined to be 364,900 cfs with a corresponding peak stage elevation of 939.2 ft. mslfrom the discharge rating curve.A probable maximum summer storm over the project area was also studied in detail andthe resulting flood at the project site determined. Although the summer storm was muchlarger than the spring storm, the initial retention rate of zero for spring conditions, andthe snowmelt contribution to runoff, resulted in the spring storm producing the morecritical flood.Key Assumptions Used to Determine Design Basis Flood HazardThe PMF evaluation for the spring storm conservatively maximizes the potential snowcover and precipitation. A limiting temperature sequence that results in an imperviousground surface due to subfreezing temperatures is assumed. This is followed byextreme high temperatures, and a subsequent major spring storm. The snowmelt andPage 3 of 11 rainfall maximizes the runoff to the river basin. This sequence of events is postulated toproduce a PMF. Additional details regarding key assumptions used in the analyses aredescribed in USAR Appendix G.Methodology Used to Develop Design Basis Flood HazardThe predicted flood discharge flow and PMF level at the MNGP site was defined usingDepartment of the Army, Office of the Chief of Engineers, the U.S. Army Corps ofEngineers, Engineer Circular No. 1110-2-27, Enclosure 2, "Policies and ProceduresPertaining to Determination of Spillway Capacities and Freeboard Allowances for Dams,"dated August 1, 1966 (Reference 2).The PMF at the MNGP site was determined by transposing an actual critical springstorm to the drainage basin and maximizing the precipitation for potential moisture.Potential snow cover and a critical temperature sequence were developed fordetermining snowmelt contribution to flood runoff.The study area was divided into four major sub-basins and synthetic unit hydrographswere developed for each, using Snyder's method, which is derived from the variousphysical basin characteristics. Unit hydrograph peaks were also increased by 25 percentand basin lag decreased by one-sixth, in accordance with standard Corps of Engineerpractice.Snowmelt and rainfall excesses were applied to unit hydrographs and the resultinghydrographs determined for each sub-basin. Sub-basin hydrographs were then routed tothe project site by computer program using the modified Wilson method. Travel times forflood routing were taken from Corps of Engineers recorded travel times for large floods.Base flow was determined from long-term records of stream flow for nearby stations.Base flow was then added to the total of the routed flood hydrographs.The stage-discharge curve at the MNGP Site was extended above the range of historicalexperience by means of hydraulic computations based on the river channel downstream.This was done by a series of backwater computations based on a range of discharges.Backwater computations were made using water surface elevations and theircorresponding discharges as determined from the rating curve downstream fromMonticello. Using the discharges and the resulting water surface elevations, a stagedischarge curve was constructed for the site.ResultsThe detailed analysis results are presented in USAR Appendix G. To summarize, theanalysis predicts a probable maximum discharge of 364,900 cfs and a correspondingpeak stage of elevation 939.2 ft. msl. The flood would reach maximum river level inabout 12 days after the beginning of high temperatures, and it was estimated the floodstage would remain above elevation 930.0 ft. msl for approximately 11 days.It is noted that the 12 day time period is for the river elevation to reach the peak level.Other important levels are the elevation of the Intake Structure (919 ft.) and Plant Grade(930 ft.). Based on USAR Appendix G Exhibits 8 and 9, water elevation of 919 ft. couldbe exceeded at about the fourth day and water elevation of 930 ft. could be exceeded atthe eighth day.Page 4 of 11 2.2.2 Floods due to Ice Dam Build-UpFlooding due to backwater, usually caused by ice jams, was considered. USAR,Appendix G, Chapter II, Page G.2-5 states that two types of flooding occur in the basin --open-water flooding and backwater flooding. Flooding while open-water conditionsprevail is caused by runoff producing rains, or by melting snow, or by a combination ofthe two. Flooding because of backwater is usually caused by ice jams. The most seriousflooding throughout the basin has been associated with excessive snowmelt and rainfall.Thus, the open-water flooding was considered to be more limiting that the backwaterflooding, and was analyzed in detail in the USAR.3.0 FLOOD MITIGATION STRATEGYFlood protection features and flood mitigation procedures are described below. The PMFevent is applicable to all modes of operation (i.e., power operation, startup, hotshutdown, cold shutdown, and refueling). Flood Protection requirements necessary toprevent external flooding or flood damage to Class I Structures or Class II structureshousing Class I equipment, are identified in USAR Section 12.2.1.7.1. Flood protectionfeatures utilized at MNGP in the event of a PMF include both incorporated (installed) andtemporary active and passive barriers. MNGP does not rely upon any flood protectionfeatures external to the immediate plant area as part of the current licensing basis thatprotect safety related systems, structures and components from inundation andstatic/dynamic effects of external floods.Incorporated engineered passive or active flood protection features are features that arepermanently installed in the plant that protect safety related systems, structures, andcomponents from inundation and static/dynamic effects of external flooding. Examplesinclude external walls and penetration seals that are permanently incorporated into aplant structure.Temporary passive or active flood protection features at MNGP include portable pumps,sandbags, plastic sheeting, steel plates, levees, etc., that protect safety related systems,structures and components from the effects of external flooding.These features aretemporary in nature, i.e., they are installed prior to design basis external flood levelsattaining specific levels.The following Class I and II structures are protected from flooding up to 939.2 ft. msl:1. Reactor Building (including High Pressure Coolant Injection (HPCI) structure)2. Turbine Building3. Intake Structure (including access tunnel)4. Off-gas Stack and Compressed Gas Storage Building5. Radwaste Building6. Diesel Generator Building7. Plant Control and Cable Spreading Structure8. Emergency Filtration Train (EFT) Building9. Diesel Fuel Oil Pump House10. Diesel Oil Storage TankPage 5 of 11 Flood preparations at the site begin with a flood surveillance procedure (Reference 6).During the time period of interest the surveillance was initiated by procedure annually inthe late winter. The procedure is currently performed monthly for river level predictionsand an annual performance includes inventory and inspection in addition to the riverlevel prediction. The purpose of this procedure is to determine if the potential for plantflood exist prior to and during the spring flooding season to ensure adequate steps aretaken to protect the plant if the potential for flooding exists. The actions taken inReference 6 are summarized as follows:* Based on the nature of the design basis flood (heavy snow pack,thawing/freezing cycle, coupled with heavy rain) the flood scenario is slowdeveloping and flood levels are generally predictable. Reference 6 determinesthe potential for flooding based on forecast information from the NationalWeather Service and river level monitoring. Procedure A.6 (Reference 7), Noteto Step 5.2.1, indicates that the National Weather Service Flow ExceedanceProbability Forecast on internet http://www.crh.noaa.qov is used to forecast riverelevations. The information for the St. Cloud and Anoka measurement stations isprovided on a weekly basis in terms of the probability that the river flow willexceed a given flow rate. The prediction information at the website is for the next90 days based on current conditions. A flow discharge curve in Reference 7 isused to determine predicted river water elevation based on the predicted flowrate. Given the conditions that precede the PMF; i.e., snowpack with thawing andrefreezing, it is reasonable to expect that the responsible individuals at the plant(engineering, operations, management) would be keenly aware of the need tomonitor river water elevations for predicted flood conditions. Increasedmonitoring and use of the predictive National Weather Service tools wouldincrease the time available to implement flood protective actions." Flood preparation measures are taken as part of Reference 6 to ensure that floodprotection materials such as sandbags, steel plates, covers and gaskets, andplugs are available. Contact information for vendors that would be used as part offlood preparation activities are confirmed to still be valid. This contact informationincludes vendors that would be involved with construction of the bin wall andearthen levee. These actions are implemented even if flood conditions are notpredicted. A memorandum of understanding is in place with VeitVeit & Company,a local construction firm, to provide construction related services in the event of asite emergency, and would cover activities such as construction of the earthenlevee." In the event that the potential for flood conditions, dump trucks and excavatorsare ensured to be available for installation of the levee, and a detailed flood planis developed.MNGP Procedure A.6 (Reference 7), "Acts of Nature," (Part 5 -.External Flooding)stipulates the actions to be taken in the event flood waters are predicted to exceedelevation 918 ft. Revision 41 through Revision 45 of Procedure A.6 (Reference 7) werein effect during the period of time from February 29, 2012 through February 15, 2013.Revision 41 was issued on February 28, 2012 and Revision 45 was issued on February14, 2013.Page 6 of 11 The following summarize the actions in A.6 based on the different predicted flood waterelevations.* Step 5.2.8, river level is predicted to exceed elevation 918 ft. Notification ofUnusual Event is declared. Actions are taken to protect equipment such as thedischarge structure substation.* Step 5.2.9, river level is predicted to exceed elevation 919 ft. Actions are taken toprotect the Intake Structure from flooding. As noted above the Intake Structure isat elevation 919 feet.* Step 5.2.10, river level is predicted to exceed elevation 921 ft. An Alert isdeclared and the plant is shutdown and cooled down to cold shutdownconditions. Actions are taken to ensure a supply of service water is available.* Step 5.2.11, river level is predicted to exceed elevation 930 ft. The bin walls andearthen levee are built. Steel plates are installed on the outside roof areas of theIntake Structure. Yard drains and other paths that could result in a water pathwaythat bypasses the levee are closed. An alternate access route to the plant isprovided from higher ground in the event that the normal access road is flooded.The levee is designed to provide flood protection up to a river elevation of 941 ft.Backup flood protection to the levee can be provided by closing up the variousbuildings using steel plates, installing sand bags, etc. It is noted that the levee isidentified in the procedure as the preferred option but, per the procedure, thebackup flood protection can be used in lieu of constructing the levee. This isdiscussed in more detail below." The remaining Steps 5.2.12 and 5.2.13 provide additional backup floodprotection for predicted river elevations above 930 feet. These are backup floodprotection measures to the levee.As described in A.6, Step 5.2.11, Note 2, the preferred flood protection measure isconstruction of a levee around the plant. The decision to use the levee as the preferredflood protection is based on a recommendation from the US Army Corps of Engineers(USACE), letter dated November 8, 2001. This USACE letter is referred to in the Basesdiscussion for Part 5 of Reference 7. However, Reference 7 includes an option forproviding flood protection in lieu of construction of the levee. This optional floodprotection means involves installing barriers (steel plates, etc.), sandbags, and sealingpenetrations. Resource loaded schedules developed in support of the A.6 proceduredemonstrate that the activities were achievable in the time required. Recent simulationsand demonstrations confirm the construction time for the bin wall, steel plate installationand sand bagging.As shown on Figure 13.10 of Reference 7, construction of the levee includesconstruction of a bin wall to the immediate east and west of the Intake Structure. The binwall was added as part of Revision 41 to A.6 on February 28, 2012. Prior to Revision41, the levee was made entirely of earthen material. The decision to use the bin wall wasbased on an analysis performed by Short Elliot Hendrickson, Inc., (SEH) (Reference 8).As part of this same change, the configuration of the levee was modified from a ringlevee entirely around the plant to a horseshoe design that ties into areas of the site thatPage 7 of 11 are above the peak PMF water elevation. The recommendation to use the bin wall wasmade as part of Reference 8 after considering various options for the tie to the IntakeStructure. Reference 8 included the following recommendations:* Secure a borrow source of levee fill within 15 minutes of the site or purchase andstore on site.* Purchase bin wall materials, assemble in modules to reduce installation timeframe, and store on site.The deficiencies identified in Reference 5 have subsequently been addressed. Inaddition to the noted deficiencies, other areas were also identified for improvement tothe plant and procedures. All of these areas for improvement were entered into the plantcorrective action system.Additional actions have been implemented to further improve the flood protection at thesite. These additional actions are summarized below:* Bin wall materials have been procured and are now stored on site. Theprocurement of the bin walls took approximately eight weeks; however, this wastreated as a normal procurement. The bin walls were supplied by ContechEngineered Solutions. Based on discussions with Contech Engineered Solutionsit is estimated that the bin wall sections could be provided in approximately 14days in an emergency situation. As discussed above, in the event that the binwalls cannot be constructed due to unavailability of materials, flood protectioncould still be provided as stipulated in the procedure using the sandbag and floodbarrier option. This option is independent of the levee and bin walls.* Levee materials have been procured and are now stored on site. Levee materialswere delivered to the site within four 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months shifts.* External flood surveillance procedure, 1478, (Reference 6) has been improved toincrease the frequency of river level monitoring during potential floodingconditions. The additional river level monitoring ensures timely plant preparationfor a potential flood. The increased river level monitoring serves to provide earlierwarning of predicted flood levels and increases available time to implementprotective actions.* Procedure A.6 (Reference 7) has been revised to improve the procedure clarity,remove unnecessary steps, and ensure completeness of protective actions." Detailed work instructions have been developed to implement actions in A.6.The work instructions provide the technical detail necessary to implement therequired action. Pre-staging the work instructions prior to the event reduces therequired time frames to implement the required actions in A.6.* Monticello conducted a self-assessment of the site flood protection response totake an additional critical review. The self assessment was performed by a teamof Xcel and contract professionals experienced in areas of flood protection.Page 8 of 11 Specific areas for improvement were identified during the self assessment andwere entered in the corrective action program and are being actively addressed.4.0 FLOOD MITIGATION STRATEGY -FURTHER DEMONSTRATIONSTable top walkthroughs of procedure A.6 have been performed to demonstrate feasibilityof performance of the required actions. A detailed schedule is developed for the actionsin A.6 using input from the site departments who would execute the actions. Theschedule shows actions to be performed, time frames, and sequencing, anddemonstrates that the actions can be completed within the available time period.Detailed work instructions have been developed to implement the actions in A.6. Pre-staging of the work instructions reduces the overall time to perform the tasks byremoving the time associated with work planning, identifies that materials that may beneeded to accomplish the work, and identifies any potential interferences orimpediments to completing the required task ahead of time.As described in Section 3.0, above, the materials to construct the bin wall sections andthe earthen levee have been procured and are stored on site. As previously discussed, amemorandum of understanding (MOU) is in place with VeitVeit & Company, a localconstruction firm, to provide equipment and services for construction of the bin wall andearthen levee.Reasonable simulation of construction of several of the actions believed to be more timeconsuming was performed in order to demonstrate that the actions could be performedwithin the available time frame. Specific actions examined were construction and fillingof the bin walls, construction of the steel plates around the roof of the Intake Structure,and filling of sandbags. The results from these reasonable simulations are summarizedbelow.* Construction of bin walls. For the reasonable simulation, approximately 5% of thetotal bin wall sections were constructed and filled. The simulation was contractedto Veit to add realism per our MOU and exercise the mobilization of personnel.The reasonable simulation took 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months for one crew to fully construct and fill.Based on using six crews, available per our MOU, to construct and fill the binwalls during implementation of procedure A.6, this would indicate that the entirebin wall sections could be fully constructed within 1.4 days. Accounting for issuessuch as excavation, inclement weather, security concerns, coordination, totalconstruction time of four days is reasonable.* Steel plates around roof of Intake Structure. As part of procedure A.6 steel platesare attached to the wall of the Intake Structure with anchors and the seamsbetween the plates welded to form part of the flood protection barrier. For thereasonable simulation, approximately 20% of the plates were installed on amock-up. The reasonable simulation took 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months and 11 minutes. Based on onewelder all of the plates could be installed within 16 hours1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months . Using two welderswould reduce this time to 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . Additional welders would reduce this timeeven more. This time period is much less than the available time and providesmargin for working in inclement weather conditions.Page 9 of 11 Sandbagging. Per procedure A.6, approximately 100,000 sandbags are filled.Sandbags are used in several steps in A.6 to seal openings, provide backupflood protection. Sandbags are critical in the event that the sandbag and floodbarrier option were implemented in A.6 in lieu of the levee option. Reasonablesimulation indicates that 600 sandbags can be filled per hour using one machineand 8 people. Go-Baggers are a manual bagging apparatus with which anindividual can fill 55 bags an hour. With one machine and 20 people workingaround the clock, the 100,000 sandbags can be filled in 2 1/2 days. Reasonablesimulation also showed that a steel double door can be sandbagged by fivepersonnel in 34 minutes. Furthermore, it was shown that laying lumber andsandbagging 1 EDG room can be accomplished by 14 personnel in four hours.In the three cases discussed above, the reasonable simulation concluded that therequired actions can be accomplished within the available time frame.5.0 CONCLUSIONSThe following conclusions are drawn from the above discussion:* The postulated flood scenario for the MNGP is considered to be veryconservative. The methodology employed provides conservative results. Thiscan be seen from the comparison of river flow rates and water elevations inTable 1 in Section 2.1, above.* The flood is a relatively slow developing evolution that allows time for plant staffto monitor, predict and implement appropriate actions to provide the requiredflood protection.* The flood mitigation procedure clearly identifies actions for plant staff toimplement to provide the required flood protection.* In the event that the levee were not able to be constructed due to not having thebin wall materials available, the procedure provides an optional approach toimplement flood protection without relying on the levee and bin wall system.Table top review of the steps to implement this optional means of floodprotection demonstrated that the protection could be provided within theavailable time.* Subsequently actions have been taken to procure the bin wall and leveematerials. Reasonable simulation has demonstrated that the levee and bin wallsystem can be installed well within the available time.Page 10 of 11 6.0 REFERENCES1. Monticello Nuclear Generating Plant, Updated Safety Analysis Report (USAR), Revision 29.2. Department of the Army, Office of the Chief of Engineers, the U.S. Army Corps ofEngineers, Engineer Circular No. 1110-2-27, Enclosure 2, "Policies and ProceduresPertaining to Determination of Spillway Capacities and Freeboard Allowances for Dams,"dated August 1, 1966.3. NRC Letter to Licensees, dated March 12,2012, "Request for Information Pursuant to Title10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1,2.3, and9.3 of the Near Term Task Force Review of Insights from the Fukushima Daiichi Accident"(ADAMS Accession No. ML 12053A340).4. NEI 12-07, Revision O-A, "Guidelines for Performing Verification Walkdowns of Plant FloodProtection Features," dated May 2012 (ADAMS Accession No. ML 12173A215).5. Xcel Energy Letter L-MT-1 2-097, "MNGP Final Response to NRC Request for InformationPursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of theNear-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," datedNovember 27, 2012.6. Procedure 1478, "External Flood Surveillance," Revision 7. [Revision 7 is the procedurerevision currently in effect. During 2012, Revisions 4 through 6 was in effect and theprocedure was titled "Annual Flood Surveillance."]7. Procedure A.6, "Acts of Nature," Revision 46. [Revision 46 is the procedure revisioncurrently in effect. When used, previous revision numbers are identified in the text.]8. Xcel Contract No. 38398, SEH No. MONNE 117980, "Monticello Nuclear Generation Plant,External Flooding Plan Update: Alternative Analysis and Final Design Report," datedJanuary 5, 2012.Page 11 of 11 Enclosure 4Monticello Nuclear Generating Plant"Annual Exceedance Probability Estimates for Mississippi River Stages at theMonticello Nuclear Generating Plant based on At-site Data for Spring and SummerAnnual Peak Floods"12 Pages Follow Annual Exceedance Probability Estimates for Mississippi River Stages at the Monticello NuclearGenerating Plant based on At-site Data for Spring and Summer Annual Peak FloodsDavid S. Bowles and Sanjay S. ChauhanRAC Engineers & EconomistsJune 28, 2013Purpose:To estimate the annual exceedance probabilities (AEPs) for Mississippi River Stages 917, 930 and 935 ft.NGVD 29 at the Monticello Nuclear Generating Plant (MNGP) using at-site data for spring and summerfloods.These estimates are intended to improve on the previous annual peak flood estimates that weresubmitted on April 8, 2013. The previous estimates were was based on an at-site flood frequency curveconstructed using a) a conservatively assigned AEP to the Harza spring PMF, and b) at-site floodfrequency estimates obtained from a drainage-area weighted interpolation between provisional USGSannual peak flood frequency estimates for the upstream and downstream Mississippi River gages at St.Cloud and Elk River, respectively.Given more time, we recommend that a Monte Carlo rainfall-runoff approach should be used to developestimates of extreme flood frequencies to make use of regional precipitation data and a morephysically-based transformation of rainfall to runoff, including snow melt and explicit consideration ofuncertainties.Available Information:Observed mean daily flows at the following locations:1) Station Number 05270700 Mississippi River at St. Cloud, MN with a period of record from 1989to 2012.2) Station Number 05275500 Mississippi River at Elk River, MN with a period of record from 1916to 1969.3) Monticello Nuclear Generating Plant (at-site) with a period of record from 1970 to 2012.Flood frequency estimates of annual peak discharges:4) Provisional 2013 USGS annual peak discharge flood frequency analyses with estimates of AEPsranging from 1 in 1.005 to 1 in 500 based on maximum daily flow rates for the annual peakflows:1 a. Station Number 05270700 Mississippi River at St. Cloud, MN with drainage area of13,320 sq. miles.b. Station Number 05275500 Mississippi River at Elk River, MN with drainage area of14,500 sq. miles.Probable maximum flood (PMF) peak discharge and stage estimates:5) Harza 1969 (spring) PMF peak discharge and river stage at the Monticello Nuclear GeneratingPlant -1912 Datum.6) Bechtel 20121 spring and summer PMF peak discharges and river stages at the MonticelloNuclear Generating Plant -NAVD88 Datum.Discharge rating relationships:7) Harza 1969 relationship between river stage (1912 Datum) and river discharge (cubic feet persecond, cfs) over the range 26,000 to 437,000 cfs.8) Ops manual equation between river discharge (cubic feet per second, cfs) up to 4,000 cfs andriver stage (NGVD 29 Datum): Q = 122(Stage -901)2.2.Datum conversions for river stages:9) NGVD 29 Datum = 1912 Datum -0.36 ft.10) NGVD 29 Datum = NAVD 88 Datum -0.4 ft.Procedure:The following two approaches were examined for developing improved at-site estimates of annualexceedance probabilities (AEPs) for the spring and summer annual floods in the Mississippi River at theMNGP:1) Drainage-area weighted interpolation of flood frequency estimates for the upstream anddownstream USGS gages: Similar to the April 8, 2013 approach, an at-site flood frequency curvewas obtained from a drainage-area weighted interpolation between flood frequency estimatesfor the upstream and downstream Mississippi River gages at St. Cloud and Elk River,respectively. However, this revised approach was conducted separately for spring and summerannual peak floods and it did not conservatively assign an AEP to the Harza PMF as was done inthe April 8, 2013 approach. Instead the flood frequency curve was extrapolated to extremefloods thus providing estimate of the AEPs for the spring and summer PMF peak flow estimatesand for the three elevations of interest.1 The report, Bechtel 2012 spring and summer PMF peak discharges and river stages at the Monticello NuclearGenerating Plant -NAVD88 Datum, has been provided to NSPM. This study provides bounding estimates to sitepeak flood elevations applicable to the development of annual exceedance probabilities at the Monticello NuclearGenerating Plan ) Flood frequency analysis based on at-site flow data: A flood frequency analysis was conductedon the available at-site streamflow data for the period 1970 to 2012 with extrapolation toextreme floods. This provided estimate of the AEPs for the three elevations of interest and forthe PMF peak flow estimates for spring and summer annual peak floods.Both of the above approaches included estimating separate flood frequency relationships for spring andsummer annual peak floods. Data for estimating these relationships were obtained using the followingdefinitions of spring and summer floods based on discussions in the Hydrologic Atlas of Minnesota (Stateof Minnesota 1959) and examination of the flow records:1) Spring annual peak floods generally peaked in the period March to May, but if it was clear fromexamination of the hydrograph that a snow melt flood event peaked in June then that peak wasused.2) Summer annual peak floods generally peaked in the June to early October period, but floodpeaks occurring in June, which were clearly associated with snow melt events, were excluded asmentioned in 1). Since the recession limb of the annual snow melt hydrograph extends throughthe summer, the peak flow rates for summer floods, which are associated with convectivestorms, are dependent to some degree on the magnitude of flow on this recession limb at thetime of the summer flood.The two approaches are discussed in more detail below.Approach 1): Drainage-area weighted interpolation of flood frequency estimates for the upstream anddownstream USGS gagesThe provisional USGS annual peak flow flood frequency estimates for the Mississippi River gages at St.Cloud and Elk River were verified using USGS flood frequency software following Bulletin #17B floodfrequency analysis procedures (USGS 1982). The following softwares were applied to the maximumdaily annual peak streamflow data assembled by the USGS to verify their results:1) PeakFQ: Bulletin #17B procedure based on method of moments parameter estimation for a LogPearson Type 3 probability distribution (Flynn et al 2006)2) PeakfqSA: The more efficient Expected Moments Algorithm (EMA) applied to the Bulletin #17Bmethodology (Cohn 2012)Following the USGS provisional analysis, the Bulletin #17B (PeakFQ) software was applied to the St Cloudgage and the EMA (PeakfqSA) software was applied to the Elk River gage for the verification step.Separate flood frequency analyses were then conducted for spring and summer annual peak flow dataat the St. Cloud and Elk River USGS gages. The maximum daily annual peak streamflow data wereassembled by the USGS and provided with their provisional flood frequency analyses. These datacomprised a mixture of spring and summer floods. These data were separated into spring and summerfloods and mean daily peak flow data were obtained from USGS flow records at both gages for thosecases that were not covered by the maximum daily annual peak streamflow data assembled by the3 USGS. An additional year (2012) of data was added for the St Cloud gage. Maximum daily annual peakflows were estimated from mean daily annual peak flows for those data not included in the USGSprovisional analyses using regression relationships established between maximum daily annual peakflow data and mean daily annual peak flow data for spring and summer flows for each gage.The PeakfqSA software containing improved EMA parameter estimation (Stedinger 2013) was applied toboth spring and summer flood data for both gages. No outliers were identified. The EMA softwareprovided AEP estimates from I in 1.0001 to I in 10,000. Estimates of annual peak discharge on theMississippi River at the MNGP were then obtained based on linear interpolations between variousfrequency (AEP) estimates developed for the St Cloud and Elk River gages as a function of drainage areawith the drainage area at the MNGP being 14,071 sq. miles. This interpolation the procedure is thesame as developed for the April 2013 AEP estimates. The at-site annual peak discharge estimates wereconverted to at-site river stages using a combination of the Harza and Ops Manual equation ratingcurves shown in Figure 1.Examination of the relationship between flood estimates for various AEPs and drainage area shown inFigure 2 showed an inconsistent relationship that was increasing or decreasing with drainage area. As aresult we have not relied on these estimates in favor of using the flood frequency estimates obtainedfrom analysis of at-site data in the second approach.947942937* 9320JS927 _______.5922 __________0JS917912907 1 1 _________9021100 1,000 10,000 100,000 1,000,000Discharge In cfs-Ops Man Eqn, Q= 122(Stage-901)^2.2 -Harza Discharge Rating -- Transition -.Final curveFigure 1. Combined Harza and Ops Manual Equation stage-discharge rating curve4 80,00070,00060,00050,0000 40,000E.30,00020,00010,000Interpolation of at-site quantiles-TFU-------- ----- ----*0.995-0.99-0.95-0.9.--0.6667ý0.5--*-0.4292-o-0.2-0.04-0.02-.--0.01-0-0.005-4-0.002-MNGS5,000U13,00013,50014,000Drainage Area (sq. miles)14,600IFigure 2. Relationships between flood estimates for various AEPs and drainage area for Approach 1Approach 2): Flood frequency analysis based on at-site flow dataThe second approach is based on extrapolation of flood frequency relationships developed from at-siteflow data. The mean daily annual peak stages were obtained for spring and summer annual peak floodsfollowing the process summarized above. Since only single observations have been recorded for eachday it was not possible to obtain maximum daily annual peak stages. The daily annual peak stages wereconverted to daily annual peak flows for spring and summer floods using the combined rating curveshown in Figure 1. The EMA (PeakfqSA) software was applied to estimate the flood frequencyrelationships for spring and summer annual peak floods. No outliers were identified for the springseason, but one low outlier (2,416 cuffs) was identified for the summer season using the MultipleGrubbs-Beck Test) low outlier identification method. The EMA software provided AEP estimates for therange 1 in 1.0001 to 1 in 10,000.Annual Exceedance Probability Estimates:Figures 3 and 4 show the resulting flood frequency estimates for the spring and summer annual peakfloods obtained from the second approach. The annual peak discharge is plotted on a Log scale andAEPs are plotted on a z-variate scale (corresponding to a Normal probability distribution). In addition to5 Monticello NGS -Spring1,000,000B el 2012 PMF estim tean--- ----a--T9. nbrPes-Tma --e .--., e.0l vafion 93SEl, -atlon 930100,000 ...... ...-, -..-'":! ... ""h...=-- -- ~ ~... :...........10,000 v-Exce dance Probability1E I 1E-1 1E-2 E-3 1E-4 iE-5 1E-6 1E-7 1E-8 1 91,000 .I I I" I 1- 1-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0z-variateFigure 3. Spring Annual Peak Flood Frequency (approximate mean shown by black dashed line)6 Monticello NGS -Summer1,000,000N024)4)4)a.100,00010,0001,000-4.0 -310 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0z-variateFigure 4. Summer Annual Peak Flood Frequency (approximate mean shown by black dashed line)7 providing median (50th percentile) and approximate mean2 estimates, the 20% (40th and 60thpercentiles), 40% (30th and 70th percentiles), 60% (20th and 80th percentiles), 80% (10th and 90thpercentiles), and 90% (5th and 95th percentiles) confidence interval estimates are provided with linearextrapolation to smaller AEPs beyond 1 in 10,000. The site elevations of 917, 930 and 935 are shown byhorizontal lines based on the NGVD 29 datum matching the datum used on the site drawings. Also theHarza and Bechtel PMF estimates are shown by horizontal lines corresponding to peak elevations forthese events.It is noted above that only single daily river stage observations have been recorded at site and thereforeit was not possible to obtain maximum daily annual peak stages. Since the difference between meandaily and maximum daily peak stages decreases with smaller AEPs, it is likely that the flood frequencyrelationships are slightly steeper than shown. This effect would tend to make AEP estimates forextreme flows slightly conservative (i.e. slightly larger) than of this effect were removed.Tables 1 and 2 contain numerical AEP estimates for spring and summer annual peak floods, respectively,for river stages 917, 930 and 935 ft. NGVD 29 for the median (50th percentile) and approximate mean,and for various confidence percentiles.Table 1. Spring Annual Peak Flood Frequency EstimatesElevation 91795th I ge 1 84th 1 0th I 70th I 60 I Median 50e 5th Approx MeanAEP Estimates 3.4E-02 2.5E-02 2.0E-02 1.7E-02 1.2E-02 8.9E-03 6.3E-03 5.9E-07 7.9E-03i in Tyears 29 40 51 59 82 112 158 1,680,000 127Elevation 93095t' 90 84th 80' 70 60h Median 50 5t Approx MeanAEP Estimates 7.OE-06 7.6E-07 7.5E-08 1.7E-08 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-91inTyears 143,0001 1,320,0001 13,400,0001 60,500,0001 >1E+9 I >1E+9 [ >1E+9 I >1E+9 [ >1E+9I _Elevation 935F-9 90 o 84th 806 70& 60' Median 506' 51 Approx MeanAEP Estimates 4.3E-07 2.OE-08 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-91 in T years 2,350,000 51,100,000 >1E+9 >1E+9 >1E+9 >1E+9 >1E+9 >1E+9 >1E+9Table 2. Summer Annual Peak Flood Frequency Estimates___Elevation 9179Sth 90t 84th 80 th 70 th 60d Median 50th 5th Approx MeanAEP Estimates 1.9E-02 1.3E-02 8.8E-03 7.2E-03 4.4E-03 2.8E-03 1.7E-03 8.5E-07 3.OE-031 in Tyears 52 79 113 140 225 358 590 1,180,000 328_ _Elevation 930_95_ 90go 84th 80eh 70th 60e Median 506h 5th Approx MeanAEP Estimates 2.1E-04 4.3E-05 8.8E-06 3.1E-06 2.4E-07 1.5E-08 < 1E-9 < 1E-9 1.6E-061in Tyears 4,7201 23,4001 11,00 324,000 4,160,000 65,100,000 >1E+9 >1E+9 641,000I-_ Elevation 93595h 90 o 841 80h 70 60'h Median 50' 5 h Approx MeanAEP Estimates 6.1E-05 7.9E-06 9.7E-07 2.5E-07 8.9E-09 < 1E-9 < 1E-9 < 1E-9 2.OE-07I in T years 16,500 127,000 1,030,000 4,000,000 112,000,000 >1E+9 >1E+9 >1E+9 1 4,930,0002 The approximate mean estimates were obtained by weighting the various percentile estimates by theirrespective intervals of probability that each represents. For example, the 60th percentile represents the intervalbetween the mid-points of the 50th -60th and 60th -70th percetile intervals and hence is weighted by thedifference between the percentiles associated with the mid-points of these two intervals, i.e. 0.65-0.55 = 0.1 The following is a summary of the median estimates and ranges (Upper -95th percentile and Lower -5thpercentile) of the AEP estimates for the river stages of 917, 930 and 935 ft. NGVD 29 at the MonticelloNuclear Generating Plant for spring and summer annual peak floods and for the Harza and Bechtel PMFestimates. The April 8, 2013 spring estimates are shown in italics for comparison. The comparisonshows that these estimate were conservative relative to those obtained using the second approach.Spring Floods:Elevation 917 ft. NGVD 29:* Upper (95th): 3.4E-02 (1 in 29/year) 4.OE-02 (1 in 25/year)" Median (50th): 6.3E-03 (1 in 158 /year) 7.2E-03 (1 in 140/year)* Lower (5th): 5.9E-07 (1 in 1,680,000 /year) 9.5E-04 (1 in 1,100/year)Elevation 930 ft. NGVD 29:* Upper (95th): 7.OE-06 (1 in 143,000 /year) 1.6E-04 (1 in 6,300/year)* Median (50th): < 1E-9 (1 in >1E+9 /year) 1.6E-05 (1 in 61,000/year)* Lower (5th): < 1E-9 (1 in >1E+9 /year) 2.2E-06 (1 in 460,000/year)Elevation 935 ft. NGVD 29:* Upper (95th): 4.3E-07 (1 in 2,350,000 /year) 3.OE-05 (1 in 33,000/year)* Median (50th): <1E-9 (1 in >1E+9 /year) 3.1E-06 (1 in 330,000/year)* Lower (5th): <1E-9 (1 in >1E+9 /year) 3.4E-07 (1 in 2,900,000/year)The Harza Spring PMF AEP estimates are shown below with the April 8, 2013 AEPs assigned to the Harza(spring) PMF shown in italics for comparison.* Upper (95th): 5.9E-08 (1 in 16,900,000) 1 in 10,000,000* Median (50th): < 1E-9 (1 in >1E+9 /year) 1 in 1,000,000" Lower (5 h): <1E-9 (1 in >1E+9 /year) 1 in 100,000The estimates of AEPs assigned to the Harza PMF in the April 8, 2013 work are therefore confirmed tobe conservative (i.e. larger than now estimated).The AEP Bechtel spring PMF estimates are shown below:" Upper (95th): 1.8E-08 (1 in 54,500,000)* Median (50th): < 1E-9 (1 in >1E+9 /year)* Lower (5th): < 1E-9 (1 in >1E+9 /year)9 Summer Floods:Elevation 917 ft. NGVD 29:* Upper (95th):* Median (50th):* Lower (5th):1.9.4E-02 (1 in 52 /year)1.7E-03 (1 in 590 /year)8.5E-07 (1 in 1,180,000 /year)Elevation 930 ft. NGVD 29:* Upper (95th):* Median (50th):" Lower (5th):2.1E-04 (1 in 4,720 /year)< 1E-9 (1 in >1E+9 /year)<1E-9 (in >1E+9/year)Elevation 935 ft. NGVD 29:000Upper (95th):Median (50th):Lower (5th):6.1E-05 (1 in 16,500 /year)< 1E-9 (1 in >1E+9 /year)< 1E-9 (1 in >1E+9/year)The AEP Bechtel summer PMF estimates are shown below:* Upper (95th):* Median (50th):* Lower (5th):5.7E-04 (1 in 1,750/year)3.3E-08 (1 in 29,900,000 /year)< 1E-9 (1 in >1E+9/year)The second approach used to develop these revised AEP estimates is preferred to the initial approachused to develop our April 2013 estimates for the following reasons:1) It separates the spring and summer flood events.2) It relies on at-site date rather than a drainage-area weighted interpolation of AEP estimates atupstream and downstream Mississippi River USGS gages.3) It does not rely on an assignment of an AEPtothe PMF.A graphical comparison of the April 2013 and the current estimates is presented in Figure 5. It indicatesthat the April 2013 AEP estimates are likely overly conservative as a result of the assignments of theAEPs to the Harza PMF.Figure 5 is similar to Figure 3 but includes the USNRC (2013) AEP estimates: 9.37E-05 for Elevation 930and 2.72E-05 for Elevation 935 (based on 6.65E-05/year for Elevation 930-935). The NRC estimatesexceed our current 95th percentile estimates but are very similar to our April 2013 95th percentileestimates, which were based on assigning an AEP of 1E-5 to the Harza PMF. According to USNRC (2013)their estimates are based on flood frequency estimates from the Monticello USAR and IPEEE but we arenot clear about the origin of those estimates or the curve fitting approach that was used by the USNRC(2013). Therefore it is not possible to make a more informed comparison with our estimates; although it10 Monticello NGS -Spring1,000,000z99LaJtU.X100,00010,0001,000-4.0-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0z-variate-April 2013 Best Estimate --April 2013 Upper Estimate --April 2013 Lower Estimate * NRC Estimates -Approx Mean6.0Figure 5. Comparison of the current Spring Annual Peak Flood Frequency with the April 2013 estimates and the NRC (2013) estimates11 would appear that our estimates rely on more recent site-specific data than the NRC had available. Inaddition they use the Bulletin #17B flood frequency approach, which is the standard for flood frequencyanalysis in the US. We also used the improved EMA parameter estimation approach that will beincluded in the revision of the Bulletin #17B procedure that has been drafted.However, we recommend that a Monte Carlo rainfall-runoff approach be considered to developestimates of extreme flood frequencies with explicit consideration of uncertainties in the future. Thisapproach can be expected to provide improved estimates based on the use of regional rainfall analysis,and a more physics-based representation of the rainfall-runoff (including snow melt) processes forextreme floods than is associated with the current extrapolation approach.ReferencesCohn, T. 2012. User Manual for Program PeakfqSA Flood-Frequency Analysis with the ExpectedMoments Algorithm DRAFT. September.Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User's Manual for Program PeakFQ Annual Flood-Frequency Analysis Using Bulletin 17B Guidelines: U.S. Geological Survey, Techniques andMethods Book 4, Chapter B4; 42 pgs.State of Minnesota. 1959. Hydrologic Atlas of Minnesota. Davison of Water, Department ofConservation, State of Minnesota.Stedinger, J.R. V. Griffis, A. Veilleux, E. Martins, and T. Cohn. 2013. Extreme Flood Frequency Analysis:Concepts, Philosophy and Strategies. Proceedings of the "Workshop on Probabilistic FloodHazard Assessment (PFHA)" sponsored by the U.S. Nuclear Regulatory Commission's Offices ofNuclear Regulatory Research, Nuclear Reactor Regulation and New Reactors in cooperation withU.S. Department of Energy, Federal Energy Regulatory Commission, U.S. Army Corps ofEngineers, Bureau of Reclamation and U.S. Geological Survey organized. Rockville, Maryland.January 29 -31.USGS (US Geological Survey). 1982. Guidelines for Determining Flood Flow Frequency. Bulletin #17B,Hydrology Subcommittee, Interagency Advisory Committee on Water Data, Office of Water dataCoordination.USNRC (U.S. Nuclear Regulatory Commission). 2013. Monticello Nuclear Generating Plant, NRCInspection Report 05000263/2013008; Preliminary Yellow Finding.12 Enclosure 5Monticello Nuclear Generating Plant"Stakeholder Outreach"I Page Follows Stakeholder OutreachNSPM hosted an open house on Thursday, June 6, from 4 p.m.-8 p.m. to shareinformation with its community neighbors on operations and preparedness to handlepotential emergencies and how we would respond to flooding, earthquakes and otherunforeseen challenges. The Site employed numerous methods to publicize the event:personal, direct invitations to community leaders, a full page ad was purchased inweekly newspapers, a news release was distributed to local media and 14,000postcards were mailed to neighbors in surrounding communities. The outreach eventhad full corporate support and the Xcel Energy Chairman, President and CEO, and theChief Nuclear Officer attended, as well as numerous senior members of the corporatenuclear staff. The Monticello Site Vice President and Plant Manager were also joined bythe site's senior leadership team at the event.A total of 515 persons from Monticello and surrounding communities attended the eventat the Monticello Training Center.The key message presented to visitors was that safety and security at the NSPM nucleargenerating plants are top priorities for Xcel Energy. Further, that we understand theNRC's increased scrutiny of safety and flood preparedness at the nation's nuclear powerplants in the wake of events such as 9/11 and Fukushima Daiichi. The Monticello FloodProtection Strategy was identified and explained to demonstrate that the site is designedto withstand a hypothetical flood beyond anything reported in the Monticello area. Thebroad underlying key messages were reinforced and manifest in specific subject itemssuch as: B.5.b Pump/Electrical Generator/Trailer, Portable Emergency ResponseEquipment, Backup Power Sources including description of backups to the backup(Battery Systems) and the continual focus on improving emergency preparednesscapabilities.Page 1 of 1

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