ML14220A283

Summary of August 5, 2014, Closed Meeting Between Representatives of the U.S. Army Corps of Engineers, NRC, and Northern States Power Company - Minnesota to Discuss Flooding Analysis Associated with Monticello and Prairie Island Nuclear Gen

ML14220A283
Person / Time
Site:	Monticello, Prairie Island
Issue date:	09/08/2014
From:	Joseph Sebrosky Japan Lessons-Learned Division
To:	Office of Nuclear Reactor Regulation
Sebrosky J, NRR/JLD, 415-1132
References
TAC MF3696, TAC MF3698
Download: ML14220A283 (21)

Text

LICENSEE:

FACILITY:

SUBJECT:

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 8, 2014 Northern States Power Company - Minnesota Monticello Nuclear Generating Plant Prairie Island Nuclear Generating Plant, Units 1 and 2

SUMMARY

OF AUGUST 5, 2014, CLOSED MEETING BElWEEN REPRESENTATIVES OF THE U.S. ARMY CORPS OF ENGINEERS, U.S.

NUCLEAR REGULATORY COMMISSION, AND NORTHERN STATES POWER COMPANY-MINNESOTA TO DISCUSS FLOODING ANALYSIS ASSOCIATED WITH MONTICELLO NUCLEAR GENERATING PLANT AND PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 (TAC NOS. MF3696, MF3697 AND MF3698)

On August 5, 2014, the U.S. Nuclear Regulatory Commission (NRC) staff held a closed meeting with the U.S. Army Corps of Engineers (USAGE), and Northern States Power Company-Minnesota, doing business as Xcel Energy (Xcel), to discuss the flooding hazard reevaluation (FHR) for the Monticello Nuclear Generating Plant (MNGP) and Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2. The meeting was held at USAGE's offices in Saint Paul, Minnesota. The closed meeting notice dated July 24, 2014, can be found in the Agencywide Documents Access and Management System (ADAMS) at Accession No. ML14205A524. The agenda for the August 5, 2014, meeting, including the list of attendees, can be found in Enclosure 1. Prior to the meeting Xcel provided a list of questions associated with the USAGE FHR for the MNGP and PINGP sites. These questions were discussed during the meeting. The questions and their answers can be found in Enclosure 2.

The purpose of the meeting was to discuss the portion of the FHR the USAGE is performing under contract to the NRC for MNGP and PINGP, Units 1 and 2. By letters dated March 5, 2014, Xcel requested NRC assistance in having the USAGE perform a dam failure analysis for the Mississippi watershed for MNGP and PINGP, Units 1 and 2 (ADAMS Accession Nos.

ML14065A112 and ML14064A291, respectively). Xcel requested the NRC's assistance to support Xcel's development of a MNGP and PINGP, Units 1 and 2 flooding hazard reevaluation report (FHRR) in response to the March 12, 2012, request for information issued pursuant to Title 10 of the Code of Federal Regulations Part 50, Section 50.54(f) (ADAMS Accession No. ML12073A348).

Meeting Highlights The USAGE described the results of the screening process it performed on the dams upstream of the MGNP and PINGP sites. Consistent with guidance outlined in Japan Lessons-Learned Project Directorate (JLD) Interim Staff Guidance (ISG) JLD-ISG-2013-01, "Guidance for Assessment of Flooding Hazards Due to Dam Failure," (ADAMS Accession No. ML13151A153) the USAGE performed an analysis of the 180 dams upstream of Monticello, and 618 dams upstream of Prairie Island, and determined that there are no "potentially critical" dams that warrant a more detailed dam breach analysis. Although no dams have been identified as "potentially critical" dams, in accordance with the JLD-ISG-2013-01, USAGE will be providing the NRC with a recommendation regarding modeling of a basin-wide probable maximum flood (PMF).

Regarding the PINGP basin-wide PMF, USAGE indicated that a PMF was developed in 1985 for a dam and lock that is immediately downstream of the PINGP site. USAGE considers this PMF to be relevant to PINGP and it is likely that a USAGE detailed model for the PINGP basin-wide PMF will not be needed.

Regarding the Monticello basin-wide PMF, USAGE indicated that there is no modern basin-wide PMF that is available for this site and that USAGE will most likely recommend to the NRC that a basin-wide PMF be developed. If the USAGE does develop a basin-wide PMF analysis for Monticello it will be developed in accordance with current guidance and the USAGE will also use its knowledge of the river basin and characteristics of the dams in the basin to develop the Monticello basin-wide PMF analysis.

The following action items resulted from the meeting:

To aid in the USAGE's development of a PMF model for Monticello, Xcel will provide a list of the calculations and models that they are developing with target dates for when this information will be available. The NRC will review the list and then inform Xcel of the calculations and models that would be helpful to aid in the development of the USAGE's Monticello PMF model. Subsequent to the meeting Xcel provided the list of Monticello PMF calculations. This list can be found in Enclosure 3.

Xcel will provide a list of the calculations being developed for Prairie Island and the NRC may request these calculations to assess what, if any, differences there are between the basin-wide PMF for Prairie Island that USAGE believes is relevant and Xcel's calculations. Subsequent to the meeting Xcel provided the list of Prairie Island PMF calculations. This list can be found in Enclosure 4.

Xcel will provide a list of locations for hydrographs that Xcel would like to have for the USACE basin-wide PMF analysis. Subsequent to the meeting Xcel identified the hydrograph locations. The locations can be found in Enclosure 5.

Xcel will determine whether it would like to have PMF levels for secondary events. There was a discussion that the Monticello basin-wide PMF will most likely be based on a rain on snow event. Xcel indicated that although a summer PMF may lead to lower levels at the site, the flood may arrive at the site sooner than the rain on snow event and there could be some benefit in gaining insights from such a secondary event.

Subsequent to the meeting Xcel informed the NRC staff that it would not request USAGE to perform evaluations of any secondary flood events.

The NRC took an action to determine whether or not if in addition to providing the hydrographs associated with PMF study, which it believes is relevant to Prairie Island, if USAGE would be willing to provide the details, including assumptions, associated with this PMF study. Xcel indicated that having the USAGE PMF study as soon as possible, if available, would be helpful in its efforts of developing its own basin-wide PMF for Prairie Island which it intends to base on a site-specific probable maximum precipitation model.

The USAGE was provided an opportunity to comment on this summary prior to its issuance and their comments were addressed in the final version of this summary.

Docket Nos. 50-263, 50-282, and 50-306

Enclosures:

1. Agenda

2. Xcel Questions and Answers

3. Monticello Related Probable Maximum Flood Calculations

4. Prairie Island Probable Maximum Flood Calculations

5. Location of Hydrographs for Monticello Nuclear Generating Plant and Prairie Island Nuclear Generating Plant (PINGP) cc w/encls: Distribution via ListServ

US Army Corps of Engineers NRC/USACE Scoping Meeting Monticello and Prairie Island NPPs Aug 5, 2014

('\\~U.S.NRC USACE St. Paul District Office Executive Conference Room, 7th Floor 180 5th St E Protecting People tUld the F111 1ironment St Paul, MN 55101 Attendees:

NRC:

Andy Campbell, Ken See, Brad Harvey, Joe Sebrosky USACE Omaha:

Roger Kay, Teresa Reinig, Chris Passero USACE St. Paul:

Doug Crum, Corby Lewis, Bonnie Greenleaf, Jim Ulrick Xcel Energy:

Marty Murphy, Brian Zelenak, Richard Rohrer, Bill Partridge, Steve Kaas Black & Veatch:

Pablo Gonzalez-Quesada, Frank Means

---

Agenda Topics -----

TUESDAY MORNING AUGUST 5 Licensee Meeting Arrival for Security Screening NRC/FERC/Xcel 08:45-09:00

Introductions

ALL 09:00- 09:15

• Upper Mississippi River Watershed Management USACE 09:15- 09:45

• Hydrologic and Hydraulic Modeling Methods and USACE 09:45-10:15 Results

• Licensee's questions and answers (see next page)

Xcel/NRC/USACE 10:15-11:00 BREAK 11 :00 - 11:30 Continued discussions as necessary Xcel/NRCIUSACE 11:30- 12:00

Xcel Questions Associated With U.S. Army Corps of Engineers Flooding Hazard Reevaluation

1.

For each dam listed in the March 05, 2014 letters [Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML14065A112 and ML14064A291],

please provide the inflow and outflow hydrographs at the location of the dam under the following scenarios: all season probable maximum flood (PMF), snow season PMF, spillway design flood (SDF), 500-yr flood, 25-year flood, and "sunny day" breach. (500-yr and 25-yr-only required if seismic failure is found to be credible)

USACE I NRC Answer: The U.S. Army Corps of Engineers (USACE) has performed a preliminary screening review using the Interim Staff Guidance (ISG) to identify non-critical dams. The results show that all dams upstream of both Nuclear Power Plant (NPP) sites are potentially screened out.

For the basin-wide PMPIPMF, the USACE will determine if any credible dam failure scenarios would impact the PMF elevation. The USACE will route the resulting hydrographs using their hydrologic I hydraulic models.

Each licensee will be given in electronic form hydrographs (stage, flow and velocity) at each NPP site. The licensees may request additional hydrographs (stage, flow &

velocity) at other locations between the federal dams immediately upstream or downstream from each NPP.

The process we are proposing involves a meeting among the licensees, the U.S.

Nuclear Regulatory Commission (NRC), and USACE after the hydrographs are provided. During this meeting, any and all questions will be answered by subject matter experts (SMEs) from the USACE and NRC. Due to the sensitive security-related information in the report, the report will not be provided. The intent of the meeting is to give each licensee's representatives an opportunity to understand all of the inputs and assumptions in the analysis. We will request a preliminary list of questions be submitted in advance, and recommend you take advantage of the opportunity to the fullest extent.

2.

Please describe how cascading effects of dam breaches are accounted for during the events listed above considering that there will be in-line USACE dams and non-USACE dams both upstream and downstream of the individual dams.

USACE I NRC Answer: The USACE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

For the basin-wide PMPIPMF, the USACE will determine if any credible dam failure scenarios would impact the PMF elevation. The USACE will route the resulting hydrographs using their hydrologic I hydraulic models.

3.

For each dam listed, please determine and describe whether a dam failure is credible during a seismic event per [Japan Lessons-Learned Project Directorate (JLD)]

JLD-ISG-2013-01 and NUREGICR-7046.

USACE I NRC Answer: The USACE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

4.

For each dam listed, please determine and describe whether a dam failure is credible during the dam's PMF or SDF per JLD-ISG-2013-01 and NUREGICR-7046.

USACE I NRC Answer: The USACE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

5.

For each dam listed, please determine and describe whether a dam failure is credible during the Monticello Nuclear Generating Plant I Prairie Island Nuclear Plant watershed-wide PMP and snow season PMPisnowmelt combinations per JLD-ISG-2013-01 and NUREGICR-7046.

USACE I NRC Answer: The NRC and USACE have not begun that phase of the project. For the basin-wide PMPIPMF, the USACE will determine if any credible dam failure scenarios would impact the PMF elevation. The USACE will route the resulting hydrographs using their hydrologic I hydraulic models.

6.

Please state whether the USACE dam breach hydrographs are consistent with the watershed-wide all season probable maximum precipitation (PMP) and snow season PMPisnowmelt combinations per JLD-ISG-2013-01 and NUREGICR-7046. If the hydrographs are not consistent with these inputs, then please describe the differences.

USACE I NRC Answer: Clarification is necessary. The USACE will provide the bounding basin-wide PMP scenario for each NPP site. For the PMF analysis, USACE will use appropriate dam breach assumptions as necessary analysis following JLD-ISG-2013-01 guidance.

7.

If the USACE is not able to provide hydrographs at the location of the individual dams, please describe whether hydrographs can be provided at other specific locations within the watershed; e.g. location of hypothetical dams. Xcel Energy would provide these locations to the USACE according to modeling needs.

USACE I NRC Answer: The USACE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

Each licensee will be given in electronic form hydrographs (stage, flow and velocity) at each NPP site. The licensees may request additional hydrographs (stage, flow &

velocity) at other locations between the federal dams immediately upstream or downstream from each NPP.

8.

Please provide the USAGE's assumptions and approach to establishing the initial (starting) pool elevations at the beginning of the flood (for failure mechanisms other than sunny-day). The Dam Failure ISG states the default starting water surface elevation should be the maximum normal pool elevation (i.e., the top of the active storage pool) but that other starting water surface elevations may be used, with appropriate justification (e.g. operating rules and history).

USACE I NRC Answer: The USAGE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

The USAGE will provide the bounding basin-wide PMP scenario for each NPP site. For the PMF analysis, USAGE will use appropriate starting water surface elevations as necessary analysis following JLD-ISG-2013-01 guidance. This analysis has not been initiated.

9.

Please describe the USAGE's approach to how failure will be triggered in the hydrologic model for the hydrologic dam failure mechanism. For example, failure could be triggered at the maximum pool during the flood, as determined by the model; the model then works out the combination of hydrographs downstream. The approach does not force peak flows from upstream dam failures to reach the plants simultaneously.

USACE I NRC Answer: The USAGE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

For the PMF analysis, USAGE will use engineering judgment to determine the hydraulic dam failure mechanisms as appropriate. This analysis has not been initiated.

10.

Please describe the method(s) for developing the breach parameters.

USACE I NRC Answer: The USAGE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

For the PMF analysis, USAGE will use accepted methods and engineering judgment to determine the breach parameters as appropriate. This analysis has not been initiated.

11.

Please describe the method(s) for routing the breach and flood hydrographs to the plants.

USACE I NRC Answer: The USAGE has performed a preliminary screening review using the ISG to identify non-critical dams. The results show that all dams upstream of both NPP sites are potentially screened out.

For the PMF analysis, USAGE and NRC are in the process of determining the path forward in terms of modeling approach. For new PMP/PMF analysis at other sites, HEC-HMS and HEC-RAS will be utilized.

12.

If the USAGE is unable to provide all the data requested, [Northern States Power Minnesota] NSPM would like to know which items will be provided.

USACE I NRC Answer: Each licensee will be given in electronic form hydrographs (stage, flow and velocity) at each NPP site. The licensees may request additional hydrographs (stage, flow & velocity) at other locations between the federal dams immediately upstream or downstream from each NPP.

The process we are proposing involves a meeting among the licensees, NRC, and USAGE after the hydrographs are provided. During this meeting, any and all questions will be answered by SME(s) from the USAGE and NRC. Due to the sensitive security-related information in the report, the report will not be provided. The intent of the meeting is to give each licensee's representatives an opportunity to understand all of the inputs and assumptions in the analysis. We will request a preliminary list of questions be submitted in advance, and recommend you take advantage of the opportunity to the fullest extent.

Monticello Probable Maximum Flood Related Calculations Calculation Site Specrftc PMP Storm E'<'ents MeteorologJ<:al Data Purpose of C<Jkulation cakulatton determines Site specrf*c all-season PMP lt also determmes the snow-season PMP and provides a meteorolocical tnne senes tdew pomt temperature and w1nds speed) used to define snowmelt condrtions durinc the snow-season PMP. These values are used as an mput to determine tne PMF for the watershed.

Historical meteorologiCal data has been compiled for the April 1965 and Apnl 2001 events. Data sncludes precipitation.

dew pomt temperature and snow pack data. Also, snow water equiValent ts calculated from snow pack data and other meteorological data. These data are used as tnputs to Glilbrate the HEC-HMS model.

180999.51.1003. PMF H~*drology I Thrs GllculatJOn has two components.

Calculatton uses tustoricai prectpnatton. snow water content and streamgage data to caltbrate tne HEC-HMS model The calibrated model is then used to Gllculate runoff due to prectpnat10n and snowmelt and routes the runoff to points Target Date 8/29/2014 9/12/2014 915/2014 9/19/2014 8/29/2014 cakulation Condition on Target D<Jte Draft Approved Draft Appro**ed CalculatiOn is m an unapproved state pending the followmg.

• Refinement of calibratiOn Parameters. calibration has been completed using limllted meteorological data that results m a conservatiVe appronmation of calibrated parameters. AdditiOnal

C,a&culation Purpose of calculation Tarr:et Date calculation condition on Tarcet I I

Date I I upstream of the site usmg the meteorologiCal data has bee-n calibrated HfC*HMS model comptle-d that wouid allow further refinement of the calibration

• Development of the new site specrfic preapitation and snowmelt u,napprowd calcu,iation mputs are based on PMP *lalues from HMR-51/52/53. Thts calculation would be updated with mputs based on site specific PMP valu,es.

!t ts not dear that this calculation tn its current state would be of any use for the US.ACE analySts

!t would be expected that the USACf would perform callbrattons/vahdations of ther routmg models Calculation Purpose of c.alcutaion nrget~te cak:ulation condition on Target Date 180999.51.1006, MNGP catculatton determined precipitatiOn and Probable Maxmum PrecipitatiOn snov.*melt for determminc run-off for the and Scnowmelt w-atershed. As part of the t\\terarchteal approach, the calculation was conservatr.<ely performed usutg PMP caiculatton is m an unapproved values based on HMR-51/52/53. Thts state pending recetpt of the calculatton also uses conservatrve tnputs from the site specific PMP parameters for estmattng snowmelt.

and further refinements of The conservative approXJrnattOns used tn 8/29/2014 snowmelt calculatJOns.

this calculation are mtended to be superseded by the site specific PMP

!t 15 not dear that this calculatton nput, and corresponding meteorologteal n its current state would be of conditions (dew potnt temperatures and any use for the USACE analysts.

Wlnd speeds) that are conStstent wrth the site specific PMP.

180999.51.1007. PMF Hydraulics CalculatiOn develops the HEC-RAS caiculatton is m an unapproved geometry for rout1ng the output from the state pending recerpt of the HfC-HMS model to deterrmne the water nputs from the site specific level at the site. calculation assumes PMP.

failure of all upstream dams texcept rncon.sequential dams). HypothetiCal The results from this calculation dams were conservat rvelv used to 8/29/2014 are very* conservatrve and not represent cluster of dams per conside-red to be reahstK. Thus, JLO-tSG-2013.01.

the Intention was to refine these values us1ng the site specific PMP.additional calibrations and more detailed informiiltton regiilrdinc the dam failures c... culation Purpose of calcu'-ion Tarcet Date calculation condition on Tarcet Date

t t5 not dear that this calculatiOn 111 its current state would be of any use for the USACE analysts.

The HEC*RAS model geometr~,

howeller. could be useful for the USACE Prairie Island Probable Maximum Flood Related Calculations Calculation Purpose of c.tlcul.ltion TctrgetOctte c.tkulation COndition on Tctrcet Date Site Speclftc PMP calculation determines srte speclftc ctli-season PMP It also determmes the snow-season PMP and provides a 8/29/2014 Draft meteorological ttme sel'le's 1 dew pomt temperature and w*nds speoedj used to deftne snowmelt condrtions durinc the snow-season PMP. These v*alues are used as an rnput to determin-e ttH! PM F for the watershed.

9/12/2014 Appro.. *ed Storm Events Meteorologtea!

Hrstorical meteorologiCal data has been 9/5/2014 Draft Data compiled for the April 1965 and Apnl 2001 events. Data tncfudes prec~pitat10n.

dew pomt temperature and snow pack data. Also, snow water equiValent ts 9/19/2014 Approved calculated from snow pack data and other meteorological data. These data are used as tnputs to calibrate the HfC-HMS model.

180999.51.1003. PMF Hydrology ThtS calculat)()n h.as two mam calculcttlon is m ctn unapproved components state pending the fo!lowtng

• HEC-HMS model calibratiOn calculation uses tustorical

• Refinement of calibratiOn prectprtat10n, snow water Parameters C-alibration has content and streamgage data to 8/29/2014 been completed using limited Ultbrate the HEC-HMS model meteorologiCal data that results 10 a conservatiVe

• PMF hvdrographs The calibrated approxtmation of calibrated model IS then used to calculate parameters. AddftJonal

Calculation Purpose of calculation Tarcet Date cakulation COndition on Target Date runoff due to prec1prtation and meteorologiCal data has be+n snowmelt and routes the runoff comptled th.at would allow to potnts upstream of the srte further refinement of the usmg the calibrated HEC-HMS calibratron model.

• Development of the new srte spectftc preopitation and snowmelt unapproved cakulation tnputs are based on PMP values from HMR-51/Sl/53. ThiS cakulation would be updated with rnputs based on srte specific PMP values.

!'t ts not dear that this calcul~tron

.nits current state would be of any use for the USACE analysts.

It would be expected that the USACf would perform caltbratiOru/vahdations of the*r routtng models Calculation Purpose of Qlcul*ion Target ~te calculation CMidition on Target D<lte 180999-51.1006, PINGP Probable Cil<uiatiOn determined precipitation and Maxmum Precipttauon and snowmelt for determtning rui'H)ff for the Snowmelt

.,,,.atershed. As part of the tuerarch&Cal approach. the ca lculat10n was conservatuel*( performed us*ng PMP calculation is m an unappro.. *ed

• • alues based on HMR-51/52/53 and u~s state pending recetpt of the

• .-ery conservative ilppro:umatJOns to nputs values from the site extend the PMP beyond the 20,000 specific PMP and further square mfie !rnit of the HMR gui~lines refinements of ram and i1us calculatiOn also uses con~rvatJVe S/29!2014 snowmelt calculatiOns.

parameters for estmatmg snowmelt.

The consernttve approx.rmat10ns used m It rs not dear that this calculation this calculation are tntended to be 1n its current state would be of superseded by the site specrfic PMP any use for the USACE analys1s.

nput, and corresponding rneteorologJCai condttions tdew po*nt temperatures and w1nd spHds) that are conSistent wrth the site specific PMP.

180999.51.1007, PMF Hydraulics CalculatiOn develops the HEC*RA5 Cikulat1on is m an unapproved geometry for roUting the output from the st;ate pending recetpt of the H£C-HM.S model to deter!TIIne the water nputs from the site specific t<tVel it the site. calculation assumes PMP.

failure of all upstre;am d;ams (except ncons.equential dims I. HypothetiCal The results from this calculation dams v.>ere conservatrvelv used to 8/29/2014 are very conservative and not represent cluster of dams per considered to be realistiC. rhus.

Ji.D*ISG*lOH-Ql the ntention was to refine these values usmg the site specific PMP, addttional calibration and more detatled informatiOn regarding the dam failures C.alc\\Ation Purpose of ~lcul41tion Target Date cak\\Ation condition on Target Date It IS not cl~ar that this caiculatiOn lfl iu current state would be of any use for the USACE anal~ts.

Location of Hydrographs for Monticello Nuclear Generating Plant (MGNP) and Prairie Island Nuclear Generating Plant (PINGP)

Monticello Nuclear Generating Plant Please provide the following:

1.

Flow and stage hydrographs at three (3) locations:

At river mile 902.7, At river mile 900.6 (plant site), and At river mile 899.3.

2.

Maximum flow velocities (main channel and left and right overbanks) at four (4) HEC-RAS cross sections near the plant site (plant site=river mile 900.6):

At the two (2) cross sections immediately upstream of the plant site At the cross section at the plant site At the cross section immediately downstream of the plant site The exact locations of the USACE HEC-RAS model cross-sections are not known at this time. It is presumed, however, that these four (4) HEC-RAS cross sections will be within river miles 902.7 and 899. 3.

3.

Information needed to calculate wind fetch lengths and average water depth between river miles 902.7 and 894.4 Location (GIS shapefile or equivalent) of all cross sections between river miles 902.7 and 894.4.

Maximum water surface elevations at each cross section between river miles 902.7 and 894.4.

Average water depth or top width and flow area, during maximum water surface elevation, at each cross section between river miles 902.7 and 894.4.

No hydrographs are needed nor requested for these cross sections.

The data requested can be generated automatically within HEC-RAS from standard output tables.

Prairie Island Nuclear Generating Plant Please provide the following:

1.

Flow and stage hydrogr a phs at three ( 3) locations:

At river mile 803, At river mile 798 (plant site), and At river mile 797.5.

2.

Maximum flow velocities (main channel and left and right overbanks) at four (4) HEC-RAS cross sections near the plant site (plant site=river mile 798):

At the two (2) cross sections immediately upstream of the plant site At the cross section at the plant site At the cross section immediately downstream of the plant site The exact locations of the USACE HEC-RAS model cross-sections are not known at this time. It is presumed, however, that these four HEC-RAS cross sections will be within river miles 803 and 797.5.

3.

Information needed to calculate wind fetch lengths and average water depth between river mile 814 and 784.5 Location (GIS shapefile or equivalent) of all cross sections between river miles 814 and 784.5.

Maximum water surface elevations at each cross section between river miles 814 and 784.5.

Average water depth (or top width and flow area) at each cross section between river miles 814 and 784.5.

No hydrographs are needed nor requested for these cross sections.

The data requested can be generated automatically within HEC-RAS from standard output tables.

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cross section located approximately

,fM 816

/-16

__ Miles upstream of PINGP.

sv ****-_.8-'!'f812 RMS 13 eRM811 eRM~r**

elrH RM810

/***-...,

' 1 RM809 RM808 RM807 wr s

RM 803 +I*

RM 806

./

Cross section located approximately

5 Miles upstream of PINGP RM805

• RM 804.

RM 798.0 +I*

Cross section located at PINGP'

1. H*1d'O!::'"PIY. ;n* *r:qcJe;tr*d at.

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• • If*

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/

803

• RM 801,

• RM801 1ritioo 12 PINGP

*~ i

,_ I '

RM 797.5 +I*

~

Cros~ section located approximately:

~-

0.5 Mtle downstream of PINGP RM 784.5 +I*

-~*\\.*

.f:':r3 f

.!. 7.92 RM 791) 789 e"'"'"\\

.Rf/4 eRM 1W!

RM 5

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-:-:-- RM 7tJ7 RM 784

.-t;,;t RM 783

. -~

• ~*-*f': \\

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1 2'*

2S

~~--~~~~-iiiiiiiiiiiiiiiiiiiiiiiiiMiles

• The NRC took an action to determine whether or not if in addition to providing the hydrographs associated with PMF study, which it believes is relevant to Prairie Island, if USACE would be willing to provide the details, including assumptions, associated with this PMF study. Xcel indicated that having the USACE PMF study as soon as possible, if available, would be helpful in its efforts of developing its own basin-wide PMF for Prairie Island which it intends to base on a site-specific probable maximum precipitation model.

The USACE was provided an opportunity to comment on this summary prior to its issuance and their comments were addressed in the final version of this summary.

Please direct any inquiries me at 301-415-1032 or at Joseph.Sebrosky@nrc.gov.

/RAJ Joseph M. Sebrosky, Senior Project Manager Hazards Management Branch Docket Nos. 50-263, 50-282, and 50-306

Enclosures:

1. Agenda

2. Xcel Questions and Answers Japan Lessons-Learned Division Office of Nuclear Reactor Regulation

3. Monticello Related Probable Maximum Flood Calculations

4. Prairie Island Probable Maximum Flood Calculations

5. Location of Hydrographs for Monticello Nuclear Generating Plant and Prairie Island Nuclear Generating Plant (PINGP) cc w/encls: Distribution via ListServ DISTRIBUTION:

PUBLIC JLD R/F RidsNrrPMMonticello Resource RidsNrrDoriLpl3-1 RidsNrrPMPrairielsland Resource KSee, NRO RidsNrrLASLent CCook, NRO JSebrosky, NRR BHarvey, NRO RKuntz,NRO RidsRgn3MaiiCenter Resource ADAMS A ccess1on N OS.: M f

N.

ML14205A524 M ee mg ot1ce eetmg s ummary ML 14 22 OA28 3 OFFICE NRR/JLD/JHMB/PM NRR/JLD/JHMB/LA NRO/DSEAIRHM1 /BC*

NAME JSebrosky Slent CCook DATE 09/04/14 08/08/14 09/04/14 OFFICE NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME SWhaley JSebrosky DATE 09/08/14 09/08/14 OFFICIAL RECORD COPY

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