ML20052H291
| ML20052H291 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/05/1982 |
| From: | GENERAL PUBLIC UTILITIES CORP. |
| To: | |
| Shared Package | |
| ML20052H273 | List: |
| References | |
| NUDOCS 8205200154 | |
| Download: ML20052H291 (12) | |
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HYDRAULIC SURVEY THREE MILE ISLAND NUCLEAR STATION JUNE 30, 1981
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Prepared By
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GPUN Environmental Controls Department General Public Utilities Nuclear Corporation
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8205200154 820505 DRADOCK05000g r
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Executive Summary The annual hydraulic survey of the Susquehanna River in the vicinity of the main station discharge (DSN 001) of the Three Mile Island Nuclear Station (TMINS) was performed on June 30, 1981. The purpose of the survey, required by the TMI-2 Environmental Technical Specifications, was to determine if the operation of TMINS resulted in scouring or sedimentation of the riverbed near the station discharge.
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data were collected by boat with a depthmeter within an area of the River having a radius of 300 feet from DSN 001. The location of depth measurenents relative to the station discharge was determined with a Mini-Ranger III Location System (uierowave). These data were plotted to develop a bathymetric (river bottom) contour map for comparison with previous surveys. Analysis of these data indicate no significant I
I structure.
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L TABLE OF CONTENTS SECTION TITLE PAGE
- 1. 0 Introduction 1
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2.0 Materials and Methods 1
3.0 Results 4
4.0 Conclusions 4
5.0 Reconnnendations for Future Studies 4
L Appendix A
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List of Figures Figure 1 Bathymetric Contour Map of Cooling Tower Discharge Area Figure 2 Data Point Locations - Cooling Tower Discharge Area
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1.0 INTRODUCTION
On June 30, 1981, a hydraulic survey was conducted in the vicinity of the Three Mile Island Nuclear Station (TMINS) cooling tower discharge structure. The purpose of the survey, conducted each summer, is to comply with TMINS Unit 2 Environ-
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mental Technical Specifications, Section 4.3, whereas, "That portion of the Susquehanna River in the vicinity of cooling f
tower discharge structures shall be monitored to determine the extent of scouring or sedimentation of the river bed that is occurring as a result of operating the Three Mile Island Nuclear Station." This survey was performed in accordance with ECP 1459, " Hydraulic Ef feets".
Data taken from the Harrisburg P.iver flow gauge indicates a 7:00 f
A.M. river flow of 23,200 cfs oa June 30.
Pool elevation as measured at the THINS intake structure staff gauge was approxi-mately 279.1 f t. for the duration of the survey.
2.0 MATERIALS AND METHODS 2.1 Basic Field Instrumentation MonArk 19 f t. Utility Boat f
Ray Jefferson Depthmeter Esterline Angus Datalogger Motorola Mini-Ranger III Microwave Range Location System Aluminum conduit - 9 f t., marked at 1 f t. intervals
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2.2 Mini-Renger III Range Location System The Mint-Rat.g:;c system employs two land based reference trans-ponders and an on-board receiver / transmitter and console display unit. The system operates in the microwave frequency band and requires direct line of sight between each reference station and
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the survey vessel. At previously determined intervals, the on-board receiver / transmitter queries the transponders which
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respond with a microwave signal. Based on the time elapsed between the sending of the initial signal and the detection of the response signal, the console display unit determines the distance between its current location and each of the
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shore-based transponders. It is then possible to determine the
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location of any given point relative to the two transponders by triangulation.
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Geometric considerations require that the survey vessel remain always on one side of a hypothetical line connecting the two transponder location points. One reference station was located on the eastern shore of Shelley Island and the other on the
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small, unnamed island between Shelley and Beach Islands.
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2.3 Field Procedure Field sampling was initiated the morning of June 30. The data logger, fathometer, digital cartridge tape recorder, and the Mini-Ranger console and receiver / transmitter units were all
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mounted on the boat and programmed as per manufacturer's in-l structions. The transponders were deployed at their designated sites, as described in Section 2.2.
A manual reading of the river elevation was t.eken at the intake structure staff gauge.
I Af ter deployment of all equipment transects of the study area were begun. Figure 2 showa the boat path and data point loca-tions.
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The boat travels along at a relatively elow speed, with the receiver / transmitter periodically querying the transponders for 1
boat location. The data logger receives the location coordi-
. nates and automatically records them on tape, along with the date, time and current reading of the depthmeter. A four secor.1 time interval between data frames was used. At frequent inter-vals and through the full range of depths encountered, a depth reading was taken with the calibrated pole to ensure that depth measurements recorded by the depthmeter were consistent and accura te.
Relatively shallow areas (less than three feet) were not accessible to our vessel.
1 2.4 Data Processing River elevation data taken at the intake structure staff gauge showed a river surface elevacion of 279.1 feet for the duration of the survey. The depth data collected in the field were con-verted to elevations by subtracting any given depth reading from the surf ace elevation of 279.1 feet. I
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A variable area map of the discharge area was digitized for use 1
on the Tektronix graphical display system, using the Tektronix 4956 digitizing tablet. The transponder locations were cali-I brat'ed to the area map and assigned position grid. coordinates.
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Since data point locational accuracy is especially critical in the intensive soundings of the discharge area, the southern area transponder locations were calibrated against fixed landmarks --
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in this case, the corners of the intake structure. For the range of elevations encountered in the survey area, a map of cach contour elevation was generated with different symbols
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indicating whether a data point fell above or below that parti-cular contour, elevation. Using the digitizing tablet, contour lina's were generated around the appropriate symbols and stored on a separate magnetic disk file. Figure 1 was then generated
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by drawing the area map, concour lines, and appropriate labels on a Tektronix 4663 plotter.
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Since the yearel draws about three feet of water and considering normal river bottom bathymetric variations, 'little quantitative data is available in those areas of the river with an elevation greater then 274 f t.
No contouring is attempted in these areas
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on Figure 1 3.0 RESULTS Figure 1 shows the bathymetric contoura of the river bottom in
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the area of the discharge structure. The dashed line describes
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a semi-circle whose origin is the discharge structure and whose radius is 300 f t.
Since this is the first hydraulic survey l
conducted by GPUN, the river bottom concours may only be com-pared to the contour map generated from the su vey conducted by GAI in June,1980. Refer to Figure 7 in GAI's June,1980 report.
A comparison of the two figures shows little change in the river bottom. contour lines show the same general locations and shapes. The only discernable difference between the two contour maps is that the impingement of the 270 f t. contour line at the northwestern edge of the 300 f t. semi-circle seems better developed on Figure 1 of this report that in Figure 7 of the GAI i
report. However, this difference is not considered significant at this time.
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- 1. A comparison of Figure 1 with GAI's June, 1980, data (see Appendix A), shows no significant changes in the river bottom in the area of the discharge structure.
5.0 RECOMMENDATIONS FOR FUTURE STUDIES
- 1. The Innerspace Technology 412 fathometer will be used in future surveys due to its advantages over the Ray Jefferson dep thmet er.
The Innerspace Technology unit has been shown to be more resistant to errors caused by cavitation and mud stirred up by the field vessel (see June 30-July 2 Hydrographic report, section 2. 3).
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