View source for LR-N14-0042, SL-012270, Revision 0, Salem Generating Station Flood Hazard Reevaluation, Page 2-6 Through Page 2-17

{{Adams
| number = ML14071A331
| issue date = 03/07/2014
| title = SL-012270, Revision 0, Salem Generating Station Flood Hazard Reevaluation, Page 2-6 Through Page 2-17
| author name = Blount D R, Chalfant L
| author affiliation = PSEG Nuclear, LLC, Sargent &amp; Lundy, LLC
| addressee name = 
| addressee affiliation = NRC/NRR
| docket = 05000272, 05000311
| license number = DPR-070, DPR-075
| contact person = 
| case reference number = LR-N14-0042
| document report number = SL-012270, Rev 0
| package number = ML14071A399
| document type = Environmental Report
| page count = 12
}}

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{{#Wiki_filter:PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation

SL-012270 Revision 0 Project No.: 12800-213 Page 2-6  precipitation falls directly into the cooling tower basin. A grid cell can be assigned an ARF value from 0 to 1, with 0 representing no blockage and 1 representing a grid cell that is completely blocked and removed from receiving any inflow. Si milarly, any of the eight flow directions in FLO-2D can be assigned a WRF value from 0 to 1, with 1 representing a flow direction that is completely blocked by a flow obstruction. All grid cells in the cooling tower area were completely blocked out from the model domain (i.e., ARFs and WRFs = 1). 

Levee elements were used in the FLO-2D model to represent the drainage impacts of the Vehicle Barrier System (VBS) and seawalls.
The alignment of the VBS and seawalls were derived from the site survey. These alignments were imported into the FLO-2D model and a levee was created to represent the walls. The VBS consists of concrete blocks approximately 10 ft. wide by 3.5 ft. tall. The levee crest elevati on along the VBS was set to be a constant 3.5 ft. above grade. The VBS restricts overland flow and is located in various locations around the perimeter of the Salem and Hope Creek Generating Stations. There are limited openings along 

the VBS to allow for pedestrian access and drainage. Gaps in the VBS were also added to the model to represent the opening widths shown on the site survey. 

The seawalls located near the SGS Service Water Intake Structure and Circulating Water Intake Structure at the southwestern corner of the site are also added to the model as levees to represent the blocked flow paths in this area. The elevation of the top of the seawalls is derived directly from the site survey. WRF values were applied along the VBS levee in the model. This is done to accurately represent the levee cr est length that is used in overtopping weir calculations. Since the levee alignment in FLO-2D is based on octagonal sides, if a physical levee is a straight line across a grid element then the weir length represented by octagon sides in FLO-2D could be too long resulting in higher overtopping flows. This was corrected by computing the entire length of the actual VBS levee and then comparing it with the octagonal levee length in FLO-2D, which resulted in a WRF value of 0.21. The addition of the WRFs to the model is fairly insignificant, since there is minimal levee overtopping in the model results. Refer to Figure 2.1-3 for a detailed overview of the site and the FLO-2D model input (e.g., model boundaries, 1 ft. contours, building footprints, VBS, seawalls, critical door locations, etc.). 

2.1.3 LIP Simulation 

FLO-2D is a dynamic, two-dimensional hydrologic/hydraulic flood routing model that conserves volume as it routes hydrographs in 8 flow directions over a system of square grid elements. The model routes runoff over the grid using the full dynamic wave momentum equation and a central finite difference routing scheme. The floodwave progression is affected by the surface topography and roughness values (Manning's n-values) associated with land use characteristics.  

After the FLO-2D model is developed, the model is run with the PMP rainfall event starting at time zero and following the hyetograph discussed in Subsection 2.1.1. The model simulation is run for a total of 12 hours to ensure that the maximum flood depths/elevations are captured and the duration of the flooding event established. The model output interval is set to 0.1 hours for the depth, flow, and velocity results. The default Courant Number of 0.6 is used to govern the numerical stability of the model.  

Following the model simulation run, GIS tools are used to post-process output text files to create shape files and rasters and hydrograph plots as described in Section 2.1.4 below.
PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation

SL-012270 Revision 0 Project No.: 12800-213 Page 2-7   2.1.4 LIP Event Simulation Results 

The FLO-2D model results, maximum flood depth, maximum water surface elevation and maximum velocity, are presented on Figure 2.1-5, Figure 2.1-6, Figure 2.1-7, and Figure 2.1-8. 

Throughout this section and on all associated figures, the term "maximum flood depth" refers to the maximum flood depth above grade. Figure 2.1-6 is similar to Figure 2.1-5 since it shows maximum flood depths, but Figure 2.1-6 uses a classified graphic scale to display results to more easily see the range of depth. The intent of Figure 2.1-6 is to clearly identify the flood depth levels and areas on the site with more than 0.5 ft. of depth above grade. 

2.1.4.1 Critical Door Locations 

SGS is flood protected to elevations significantly above the predicted flood depths associated with the LIP event. However, in order to implement that flood protection, water tight doors must be closed. Since the flood depths predicted in this analysis exceed the door sill elevations, the 

time to exceed the threshold is considered the critical parameter for this analysis. 

Each of the door locations is assigned a unique ID and corresponding FLO-2D grid cell from the model. There are 12 locations at grade (IDs 10-21) for Salem Generating Station (see Figure 2.1-3 for locations) which represent the location of a watertight door. At each of the door locations, the maximum WSEL, depth, and velocity were determined. The duration of flooding (i.e., the amount of time when the water surface elevation exceeds the door elevation) was also 

computed at each door location. 

The results are summarized in Table 2.1-3. In addition, depth-time hydrographs at each of the door locations were extracted from the model. These plots show the flood depths and durations for each door location, and are presented in Figures 2.1-10 through 2.1-21. Table 2.1-3 lists the corresponding figure number for each door location's hydrograph. 

2.1.4.2 Erosion Potential 

The maximum velocities in Table 2.1-3 at all critical door locations are relatively low, ranging from 0.44 to 1.37 feet per second (fps). Figure 2.1-8 also shows that the maximum velocities resulting from the LIP event are less than 2.5 fps in the immediate vicinity of all safety-related structures. In general, the areas near the door locations and surrounding the safety-related structures are highly compacted and covered with pavement, concrete, or gravel. Thus, the potential for erosion/deposition during the LIP event is low, because flow velocities less than 2.5 fps are not expected to erode these materials, according to the maximum permissible velocities shown in Chow's Open Channel Hydraulics (Reference 2.1-4). 

2.1.4.3 Final Floodplain Depths and Velocities 

In order to evaluate the duration of flooding and associated "draindown" time, the model simulation was run for 12 hours (11 hours of simulated flood routing following the 1-hour precipitation event). The model results indicate that the flood elevations will recede below all of the door elevations after 8.1 hours from the start of the 1-hour precipitation event (see Table 2.1-3).
PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation

SL-012270 Revision 0 Project No.: 12800-213 Page 2-8   The final floodplain depths at the end of 12 hours are shown on Figure 2.1-9. As shown on the figure, there will be some locations of standing or ponded water that will drain slowly or 

eventually infiltrate/evaporate. The final velocities at 12 hours are essentially negligible (less than 0.2 fps for the entire site except at a few isolated locations). 

2.1.5 Conclusions 

The model results indicate that door locations around the powerblock area will experience flood depths from 2.2 ft. to about 3.1 ft. above grade during a LIP event, resulting in a peak WSEL of 12.24 ft. NAVD or 102.0 ft. PSD. The flood depth exceeds the door sill elevations within minutes. Based on these results, the reevaluated LIP flood elevations are above the CLB and are further assessed in Chapter 3. 

The Service Water Intake Structure will not be flooded as the watertight door sill elevation is well above grade at 112 ft. PSD and is above the predicted flood elevation from the LIP event.
2.1.6 References 

2.1-1 U.S. Nuclear Regulatory Commission, "Design-Basis Flood Estimation for Site Characterization at Nuclear Power Plants in the United States of America," NUREG/CR-7046, November 2011. 2.1-2 National Oceanic and Atmospheric Administration, "Application of Probable Maximum Precipitation Estimates - United States East of the 105th Meridian," Hydrometeorological Report (HMR) No. 52, August, 1982. 2.1-3  FLO-2D Software, Inc., "FLO-2D Reference Manual," Version 2009, 2009. 2.1-4 Chow, V.T. "Open-Channel Hydraulics," Mcgraw-Hill, New York, 1959. 2.1-5 MASER Consulting, PA ALTA/ACSM Land Title Survey for PSEG Nuclear LLC of Block 26, Lots 4, 4.01, 5 and 5.01, Job Number 05001694D, Index Number HASU023453 dated June 13, 2008.
PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation

SL-012270 Revision 0 Project No.: 12800-213 Page 2-9  Table 2.1-1 1-Hour, 1 Square Mile PMP Rainfall Depths Duration Area (mi 2) Multiplier Applied to Local Intense Precipitation (in) Note 60 min 1 NA NA 18.10 HMR 52 Figure 24 30 min 1 0.753 1-hr, 1-mi 2 PMP 13.63 HMR 52 Figure 38 15 min 1 0.525 1-hr, 1-mi 2 PMP 9.50 HMR 52 Figure 37 5 min 1 0.334 1-hr, 1-mi 2 PMP 6.05 HMR 52 Figure 36 0 1 0.000 N/A 0.00 N/A PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation

SL-012270 Revision 0 Project No.: 12800-213 Page 2-10 Table 2.1-2 FLO-2D Manning's n Values Description Manning's n Grass/Vegetation 0.05 Developed/Pavement 0.03 Debris/Obstructions 0.10 

PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation

SL-012270 Revision 0 Project No.: 12800-213 Page 2-11 Table 2.1-3 LIP Analysis Results Summary at Door Locations (b)(c)  Salem Door Number Door Location ID (a) FLO-2D Grid Cell Max WSEL (ft) (NAVD) Max Flood Depth Above Grade Elevation (ft) Max Velocity(fps) Time to Max Depth (hrs) Door Elevation(ft) (NAVD) Duration of Flooding above Door Elevation (hrs) Depth-Time Plot Figure Number 2DOOR-FH103-2 10 218164 12.07 3.07 1.09 1.01 10.20 7.70 2.1-10 AUX1 11 228711 11.68 2.68 0.62 1.05 10.20 6.60 2.1-11 1DOOR-AUX4 12 229767 11.52 2.52 0.61 1.00 10.20 5.90 2.1-12 1DOOR-FH103-1 13 233928 11.52 2.52 0.56 1.00 10.20 5.90 2.1-13 1DOOR-AUX130-1 14 236010 11.43 2.43 0.44 1.01 10.20 5.40 2.1-14 1DOOR-AUX5 15 229261 11.49 2.49 0.73 1.00 10.20 5.50 2.1-15 2DOOR-AUX134-2 16 220837 12.16 3.04 1.18 0.99 10.20 7.90 2.1-16 2DOOR-AUX130-2 17 213366 12.14 2.97 0.89 0.99 10.20 7.90 2.1-17 2DOOR-N.P.-1&2 18 210680 12.24 3.07 1.37 1.00 10.20 8.00 2.1-18 1DOOR-A127-1 19 217666 12.24 2.78 0.67 1.00 10.20 8.10 2.1-19 1DOOR-A127-1 20 231368 11.36 2.23 0.5 0.99 10.20 4.70 2.1-20 1DOOR-S.P.-1&2 21 237564 11.34 2.32 0.58 1.01 10.20 4.80 2.1-21 a)  See Figure 2.1-3 for corresponding door location IDs. b)  SWIS and Service Building doors and hatches located at elevation 112 ft. PSD (22.2 ft. NAVD) and above are not listed. c)  Watertight hatches and manways inside the powerblock area are closed and sealed during normal plant operation; therefore they are not specifically listed.
PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation Figure 2.1-1 SL-012270 Revision 0 Project No.: 12800-213 1-Hour, 1-Square-Mile PMP Rainfall Distribution Plot LU I I I i I I : I i i I 18 I I 1 1 I i I 1 I I I I I "", 1.,.,-,-! I I , I ..... _16 : 1-.." I I I I ! I ""'" -r I Q) i I "5 14 I I , .5 ! k i""""" I I I I I -1 "". I -5 12 I ! I I ), I I I ! I c-QJ I I I 1 I I I 010 1 I "'jij ! U/ I I I ..... I I 1 I 0 8 l-I .X I I ! I I : I I I I I ! I I I I III 1 -6 I I , c i i i I I I I I ! I 1 I *iii ; I I i I I I I I c::: 4 I I i i I I 1 I I I I I I I I ! I I I I I I ') I I ! II I I i I I I I I I I I 0 , I I I I I 0 10 20 30 40 50 60 Time (minutes)
Page 2-12 Sargent &
PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation Figure 2.1-2 1-Hour, 1-Square-Mile PMP Rainfall Hyetograph 7.0 T 6.0 Qj 5.0 .c u ,5 :;;-4.0 -a. 4J 0 3.0 -I"CI -c 2.0 'is a:: 1.0 0.0 SL-012270 Revision 0 Project No.: 12800-213 0 5 10 15 20 25 30 35 40 45 50 5S 6 0 Ti me (m inut es) Page 2-13 Sargent &
PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation 
....... ......., Page 2-14 Figure 2.1-3 General Site Layout and FLO-2D Model Components N + PSEG -Sa l em a n d Hope C r eek Ge n e r a ti ng Stati o ns U P f PMP F L O-2D Analys i s F i gu re 3 -Genera l Site Layo ut a n d FLO-2D Mode l Co m ponen t s SL-012270 Revision 0 Project No.: 12800-213 -ay2.etn (\.'8 3) -5" m lSex CGn tlKr --l'ln t2 rmedlr.e Ce n tau r t NA V D SI} S CUXl wy C1 Su ll c l ng:;
* Cdf Ci1.1 Ooo r La c mko:o Sargent & Lundy PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation Page 2-15 Manningls n Values D Developed 
/ Pave m ent (0.03) D Grass / Vegeta t ion (0.05) _ Debris I Obs t ructions (0.1) Figure 2.1-4 FLO-2D Manning's n Values I o \ o SL-012270 Revision 0 Project No.: 12800-213 PSEG -Salem and Hope Creek Generat i ng Stations L IPIPMP FLO-2D Analys i s Figure 4 -FLO-2D Manning's n Va l ues N + D Build i ngs Veh i c l e Barrier System (VBS) 300 e o o 1 , 200 Model Outf l ow Boundary Sargent & LunctyLLC PSEG Nuclear LLC Salem Generating Station F l ood Hazard Reeva l uation Page 2-16 Maximum Depth (ft) '---High: 7.50 Low: 0.00 Figure 2.1-5 Maximum Flood Depth (Above Grade) PSEG -Salem and Hope Creek Generating Stations LlP/PMP FLO-2D Ana l ysis SL-012270 Revision 0 Project No.: 12800-213 Figure 5 -Maximum Flood Depth (Above Grade)
* Crit i ca l Door Locations N Veh i cle Barrier System (VBS 'l------r O.5-ft De p th Contour ...........
Mode l Ou tfl ow Boundary 0 30 0 600 1.2 00 CJ Bu il d i ngs Fee t Sargent & Lundy**c PSEG Nuclear LLC Salem Generating Station Flood Hazard Reevaluation Page 2-17 ax i mum Flood Depth D 0.0 -0.5 (no colo r) D 0.5-1.0 _ '1.0-1.5 _ 1.5-2.0 D 2.0-2.5 D 2.5-3.0 _ 3.0-3.5 D 3.5-4.0 _ 4.0-7.0 7.0 -12.0 Figure 2.1-6 Classified Maximum Flood Depth (Above Grade) PSEG -Salem and Hope Creek Generating Stations LlP/PMP FLO-2D A n alys i s Figure 5a-SL-012270 Revision 0 Project No.: 12800-213 Classified Maximum Flood Depth (Above G o N ,r 300 6 00 Fee l 1.200 10) Crit i ca l Door L oca ti ons Vehicle Barrier Sys t em (VBS) Model Outflow Bou n dary CJ Build i ngs Sargent & Lundy L L C}}