ML092330602

Report No. R-1903966-01, Rev. 0, Effect of Plant Structures on the Wind Speed and Direction at the Meteorological Tower at the Susquehanna Steam Electric Plant.

ML092330602
Person / Time
Site:	Susquehanna, Bell Bend
Issue date:	04/30/2008
From:	ABS Consulting
To:	Office of New Reactors, UniStar Nuclear
References
BNP-2009-184 R-1903966-01, Rev 0
Download: ML092330602 (9)

Text

Report No. R-1903966-01 Revision 0 Effect of Plant Structures on the Wind Speed and Direction at the

Meteorological Tower at the

Susquehanna Steam Electric Plant April 2008 Prepared by:

T. Edward Fenstermacher Prepared for:

UniStar Nuclear 750 East Pratt Street Baltimore, MD 21202

Contents Page 1. Introduction...............................................................................................................

..1 2. Methodology................................................................................................................

1 2.1 Wake Effects Methodology............................................................................................1 2.2 Windfield Change Methodology..................................................................................3

3. Input Data.................................................................................................................

....4 4. Results....................................................................................................................

.......7 4.1 Results of Wake Analysis..............................................................................................7 4.2 Results of the MIDAS-AT Analysis..............................................................................7 4.3 Influence of Local Meteorology....................................................................................9

5. References.................................................................................................................

..11 Tables Table 1. Locations of plant structures in both coordinate systems.......................5 Table 2. Heights of plant structures above grade.....................................................5 Table 3. Diameter of Cooling Tower at Selected Heights.......................................6 Table 4. Maximum Wake Defect for Susquehanna Structures at the Meteorological Tower...............................................................................................7 Table 5. Statistical Summary of MIDAS-AT Results..............................................9

Figures Figure 1. Schematic diagram of wake cavity from the cooling tower...................2 Figure 2. Plan View of Significant Plant Structures and the Meteorological Tower...............................................................................................4 Figure 3. Terrain Near the Plant Showing Plant Structures as Modeled in MIDAS-AT.............................................................................................................6 Figure 4. Ratio of Measured Speeds With and Without Plant Structures............8 Figure 5. Difference Between Measured Wind Directions With and Without Plant Structures..........................................................................................8 Figure 6. Wind Rose at 10 m........................................................................................10 Figure 7. Wind Rose at 60 m........................................................................................10

1. Introduction P:\current directory\R-1903966-01 (2).doc/oc 1 1. Introduction The purpose of this report is to document calculations of the effects of the presence of plant structures on the meteorological data collected at the Susquehanna Steam Electric Station. The structures included in the modeling are the cooling towers, turbine building, reactor building, control building, and radwaste building. Two methods are used to estimate the effects of these structures. The first is an analysis of the building wake using methods taken from Hosker (Reference 1). The second is to examine the differences between the windfields generated by the urban model in the MIDAS-AT code (Reference 2) when the structures are absent or present.

2. Methodology 2.1 Wake Effects Methodology The cavity length is estimated using an equation for the wake of a rectangular prism of

length L in the downwind direction, width W in the crosswind direction, and height H (Reference 1). Because the cooling towers are rounded, and the wakes of rounded objects are smaller than rectangular objects of the same dimensions, this will give an upper bound for the cavity length of the cooling tower. Equation 7.1 from Reference 1 is 3 1 3 1 305.0 15.0 7.3 0.2 0.1H L B H L A H W B H W A H L H x r (1) where the cavity is measured from the leading edge of the block. For the cooling towers, the desired result is the length of the wake from the center of the cooling tower (x c), the first line of Equation 7.1 is modified by subtracting half of the length, and the length and width are both taken to be equal to the diameter, D. Thus, the final form of the equation for the cooling tower is:

2. Methodology P:\current directory\R-1903966-01 (2).doc/oc 2 3 1 3 1 305.0 15.0 7.3 0.2 0.1 5.0H D B H D A H D B H D A H D x c (2) A schematic representation of the cooling tower and cavity (of length x c) are shown in Figure 1.

Figure 1. Schematic diagram of wake cavity from the cooling tower In section 7-4.3 of Reference 1, the maximum wake defect for a block with a square upwind face, which is the closest approximation available to the shape of both the cooling towers and the other site buildings, decays with distance as follows: 6.2 min minx x x U x U (3)

2. Methodology P:\current directory\R-1903966-01 (2).doc/oc 3 The choice of:

c x xmin (4) with 1 minx U (5) results in the most conservative estimate of the effect of the building wake on wind speed. In actuality, because the streamlines converge just beyond this point, the actual effect will be much smaller in magnitude. This gives a maximum wake defect of 6.2 maxc x x U (6) The same equation applies to the wake from a block, except that for a block, the wake separation occurs at the leading edge instead of at the maximum diameter, so in this

case x r is used in place of x c for the wake cavity length. 2.2 Windfield Change Methodology For the second part of the calculation, the changes in measured wind speed and direction were estimated using the modified potential flow model incorporated in MIDAS-AT as the urban model. The discussion in Reference 1 Section 7-4.1 indicates that potential flow should yield valid results well away from the separation streamlines, and, as the previous calculation shows, this condition is met at the location of the meteorological tower. A Microsoft Excel Spreadsheet was used to develop a model of each structure as a stack of circular cylinders. Each circle was digitized into 64 circumferential locations, and the points were converted into geographic coordinates and written to a vertex (.vrt) file, with a corresponding entry into a comma-separated value (.csv) file describing the layer. These files were processed by the RaiseTerrain program, which added them to a bare earth layer constructed from Digital Terrain Elevation Data. The output from this process is a pair of grid files, one with the terrain height without structures, and the other with the terrain height including structures. The grid elements are 10 m squares, and the elevation of each grid element is given as an integer height in meters. The MIDAS-AT model (Reference 2) was modified to output the calculated wind vector at the 10 m and 60 m elevations above grade at the location of the meteorological tower.

The code was then run for the sixteen primary directions at D stability and F stability, and the wind speed vectors at the meteorological tower location recorded at the 10 m and 60 m levels. This was done with and without the plant structures. The results were compared to determine the impact of the plant structures on measurements at the meteorological tower.

3. Input Data P:\current directory\R-1903966-01 (2).doc/oc 4 3. Input Data The locations of structures at the site were taken from a series of drawings supplied by UniStar. The general plant layout is show n in Figure 2. By comparison of the coordinates shown on the drawings with other topographic information, it was possible to

determine that the coordinate system of the drawings was Pennsylvania State Plane North using the North American Datum of 1927. The plan coordinates of the cooling towers and the corners of the turbine building, control structure, reactor building, radwaste building, and diesel generator building were measured on Reference 3. The height and diameter of the control tower at various levels was measured on Reference 4.

The heights of the turbine building, control structure, and reactor building were taken from Reference 5, the height of the radwaste building from Reference 6, and the height of the diesel generator building from Reference 7. The measured coordinates are shown in Table 1. The coordinates were transformed to the Uniform Transverse Mercator grid for the North American Datum of 1983 using the Corpscon 6.0.1 program (Reference 8). These coordinates, also shown in Table 1, were used to develop the grid for the MIDAS program. The structure heights above ground are shown in Table 2. The diameter of the cooling tower at selected heights above the ground is shown in Table 3.

Figure 2. Plan View of Significant Plant Structures and the Meteorological Tower

3. Input Data P:\current directory\R-1903966-01 (2).doc/oc 5 PA North SP NAD 1927UTM Zone 18 NAD 1983Structure Name and Point Northing, ftEasting, ftNorthing, ft Easting, ftMeteorological Tower 340900.72443290.314926149.2 1325904.8Unit 1 Cooling Tower Center 341542.52441305.414926853.3 1323941.7Unit 2 Cooling Tower Center 340807.52441305.414926118.9 1323918.4Turbine Building NW Corner 341486.32441802.014926781.5 1324436.2Turbine Building NE Corner 341486.32441969.814926776.2 1324603.8Turbine Building SE Corner 340859.62441969.814926149.9 1324584.0Turbine Building SW Corner 340859.62441802.014926155.2 1324416.3Radwaste Building NW Corner 341664.42441802.014926959.4 1324441.8Radwaste Building NE Corner 341664.42441969.814926954.1 1324609.5Radwaste Building SE Corner 341486.32441969.814926776.2 1324603.8Radwaste Building SW Corner 341486.32441802.014926781.5 1324436.2Control Structure NW Corner 341243.22441909.414926535.1 1324535.8Control Structure NE Corner 341243.22441969.814926533.2 1324596.1Control Structure SE Corner 341106.22441969.814926396.3 1324591.8Control Structure SW Corner 341106.22441909.414926398.2 1324531.5Reactor Building NW Corner 341335.62441969.814926625.6 1324599.1Reactor Building NE Corner 341335.62442100.714926621.4 1324729.8Reactor Building SE Corner 341013.72442100.714926299.8 1324719.7Reactor Building SW Corner 341013.72441969.814926303.9 1324588.9Diesel Generator Building NW Corner 341448.62442033.614926736.5 1324666.4Diesel Generator Building NE Corner341448.62442120.814926733.7 1324753.5Diesel Generator Building SE Corner341335.62442120.814926620.8 1324750.0Diesel Generator Building SW Corner341335.62442033.614926623.6 1324662.8Table 1. Locations of plant structures in both coordinate systems Building Name Height Above Grade, ft Turbine Building 113.71Radwaste Building 39.00Control Structure 150.50Reactor Building 201.58Diesel Generator Building 65.50Table 2. Heights of plant structures above grade

3. Input Data P:\current directory\R-1903966-01 (2).doc/oc 6 Height, ft Diameter, ft 0.00420.0045.75396.00136.50346.50226.50312.00303.00291.75363.75285.00433.50285.00523.50298.50540.00315.00Table 3. Diameter of Cooling Tower at Selected Heights The conversion of the input data to the terrain data grid used by MIDAS-AT is shown in Figure 3. Terrain Near the Plant Showing Plant Structures as Modeled in MIDAS-AT

4. Results P:\current directory\R-1903966-01 (2).doc/oc 7 4. Results 4.1 Results of Wake Analysis The results of the wake analysis for the major structures is shown in Table 4. The largest effect is about 17% for the reactor building. For the reasons noted in the methodology section, the actual effect would be expected to be much smaller than the wake defect.

Structure Wake Cavity Length, ft (x r or x c) Meteorological Tower Distance, ft Maximum Wake Defect Unit 1 Cooling Tower 848.7 2085.6 9.65% Unit 2 Cooling Tower 848.7 1986.6 10.96% Reactor Building 684.0 1348.3 17.13% Turbine Building 642.6 1512.6 10.80% Table 4. Maximum Wake Defect for Susquehanna Structures at the Meteorological Tower 4.2 Results of the MIDAS-AT Analysis The results of the MIDAS-AT analysis are shown in Figure 4, which shows the ratio of the measured speeds at the meteorological tower with and without the plant structures; and in Figure 5, which shows the difference in the measured wind directions at the meteorological tower with and without the plant structures. A statistical summary of the results is shown in Table 5. The wind speed deviations for F Stability at both heights range follow a nearly sinusoidal pattern from 2% lower to 1% higher, and average about 0.5% lower. The maximum effect occurs with wind from either the East or West. The effects at D Stability are only about a third as large, but follow a similar pattern. The direction differences range within about a degree either side of zero in a sinusoidal pattern offset about 45° in direction from the wind speed pattern. Again, the deviations for D Stability are only about a third as large as for F Stability.

4. Results P:\current directory\R-1903966-01 (2).doc/oc 8 Ratio of Measured Wind Speeds at Met TowerWith and Without Structures0.9750.9800.9850.9900.9951.0001.0051.0101.01504590135180225270315360Wind Direction at Reactor, Degrees From NorthWind Speed RatioF Stability, 10 mF Stability, 60 mD Stability, 10 mD Stability, 60 m Figure 4. Ratio of Measured Speeds With and Without Plant Structures Difference in Measured Wind Direction at Met TowerWith and Without Structures-1.5-1.0-0.50.00.51.004590135180225270315360Wind Direction at Reactor, Degrees From North Direction Difference, DegreesF Stability, 10 mF Stability, 60 mD Stability, 10 mD Stability, 60 m Figure 5. Difference Between Measured Wind Directions With and Without Plant Structures

4. Results P:\current directory\R-1903966-01 (2).doc/oc 9 Wind Speed Ratio Direction Difference, ° Stability Class Measurement Height, m Mean Mean 10 0.9944 0.0110 -0.14 0.68 F 60 0.9948 0.0099 -0.09 0.61 10 0.9994 0.0034 -0.04 0.19 D 60 0.9994 0.0033 -0.04 0.19 Table 5. Statistical Summary of MIDAS-AT Results Because the wake defect is an upper estimate of the effect, and the potential flow model in MIDAS-AT should give a good approximation of the flow at several wake cavity lengths, the impact of plant structures on the measured wind speed should be minimal, and the effect on the measured wind direction nearly non-existent. 4.3 Influence of Local Meteorology The predominant wind direction on the primary meteorological tower at Susquehanna has been very persistent over the last 25 years of data collection at the site. At the 10 m level the prevailing wind direction has been from the east-northeast (about 14% of the time) at the 10 m level and from the north-northeast (about 16% of the time) at the 60 m level. The secondary peak has been from the southwest at both levels on the tower.

The cooling towers and other plant structures are located from the west to the northwest of the primary meteorological tower. Winds from these three sectors occur less than 10% of the time at the 10 m level and about 12% of the time at the 60 m level during an average year. When "stable" atmospheric stability conditions are taken into consideration in conjunction with the wind direction passing through the cooling towers and other plant structure these conditions occur about 0.1% of the time at the 10 m level and about 0.4% of the time at the 60 m level. Figure 6 and Figure 7 show wind roses from the 10 and 60 m levels for a recent (2005-2007) three-year period that is representative of the long-term data at the site. Therefore the prevailing meteorology at the site will help to minimize any affects that the cooling towers and other plant structures have on the primary meteorological tower.

4. Results P:\current directory\R-1903966-01 (2).doc/oc 10 Figure 6. Wind Rose at 10 m Figure 7. Wind Rose at 60 m

5. References P:\current directory\R-1903966-01 (2).doc/oc 11 5. References 1. Randerson, Darryl, Editor, Atomic Energy and Power Production, DOE/TIC-27601.

2. MIDAS Technical Description, Attachment A, ABSG Consulting, Inc., 22 November 2002. 3. PP&L Drawing E105004, Revision 13, General Arrangement, Fence and Patrol Road , September 25, 2006. 4. PP&L Drawing CT-220-30, General Notes, Location Plan and Elevation. 5. PP&L Drawing E105005, Sheet 1, Revision 9, General Cross-Section 'A', August 2, 1994. 6. PP&L Drawing E106336, Revision 21, Equipment Location Radwaste Bldg Sections A-A and B-B , October 28, 1987. 7. PP&L Drawing E106335, Revision 5, Equipment Location Units 1 and 2 Diesel Generator Building Plan of EL. 710'9" & 723'0" Sects A-A and B-B , April 7, 1988.

8. http://crunch.tec.army.mil/software/corpscon/corpscon.html, Corps of Engineers Coordinate Conversion 6.0.1, January 3, 2008.