Text

Validation of Computerized Thermal Compliance & Plume Development at Sequoyah Nuclear Plant
	ML20086A786
Person / Time
Site:	Sequoyah
Issue date:	08/31/1983
From:	Johnson B, Mcintosh D, Speaks E; TENNESSEE VALLEY AUTHORITY
To:	;
Shared Package
ML20086A781	List: ML20086A778; ML20086A786;
References
	WR28-1-45-115, NUDOCS 8311160110
	Download: ML20086A786 (78)
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_ - - - . __ __-

WR28-1-45-115 VALIDATION OF COMPUTERIZED THERMAL COMPLIANCE AND PLUME DEVELOPMENT AT SEQUOYAH NUCLEAR PLANT 4

i m _ _, TENNESSEE VALLEY AUTHORITY L OFFICE OF NATURAL RESOURCES gyj '/\ DIVISION OF AIR AND WATER RESOURCES t i2 -

- WATER SYSTEMS DEVELOPMENT BRANCH Irv ' i NORRIS, TENNESSEE 0311160110 831014 PDR ADOCK 05000

,A Tennessee Valley Authority Office of Natural Resources

- Division of Air and Water Resources Water Systems Development Branch VALIDATION OF COMPUTERIZED THERMAL COMPLIANCE AND PLUME DEVELOPMENT AT SEQUOYAH NUCLEAR PLANT F

4 e

Report No. WR28-1-45-115 Prepared by Dave A. McIntosh Billy E. Johnson 3 and Ellen B. Speaks Norris, Tennessee August 1983

i ABSTRACT j

l

. Six field surveys were performed to acquire data for validating the computerized technique for demonstrating compliance with thermal water quality standards. The numerical model used for predicting the plant-Induced temperature rise requires as input; ambient river temperature, temperature and flowrate of the discharge, and the releases at Watts Bar and Chickamauga Dams. These data are automatically communicated to a microcomputer located at the Environmental Data Station (EDS). Computa-tions are performed at 15-minute intervals and the results transmitted to the control room at the plant.

The results of the simulation program compared favorably with the field-measured downstream temperatures. On average, the discrepancy between the measured and computed downstream temperatures was 0.22*C.

Considering that the accuracy of the temperature sensors is 10.14 C, the agreement between the field measurements and the computer model is quite close. A similar comparison of the monitored temperatures with the measured lateral averages revealed that the discrepancy for Monitor 8 was 0.44 C and for Monitor 11 was 0.36 C. Consequently, it was concluded that the computerized compliance method not only provides an accurate representation of the downstream temperature.-but also is superior to the monitored approach.

The lateral and longitudinal profiles of temperature in the surface layer indicated that the plume extends outside of the mixing zone during both one-unit and two-unit plant operation. liowever, the section of the plume that is beyond the boundaries of the mixing zone is at-temperatures -

that are well within the thermal standards applicable at SNP.

11 CONTENTS a

Page A b s tra c t . . . . . . . . . . . . . . . . . . . . . . ....... i I n trod uction . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Cooling Water Intake and Discharge Systems ........... 3 Cooling Water Intake. . . . . . . . . . . . . . . . . . . . . 3 Discharge System and Controls ............... 4 Hydrothermal Characteristics of Reservoir, . . . . . . . . . . . . 7 River Flows . . . . . . . . . . . . . . . . . . . . . . . . . 7 Temperatu res . . . . . . . . . . . . . . . . . . . . . . . . 7 Applicable Thermal Water Quality Standards . . . . . . . . . 9 Review of Laboratory Model Results . . . . . . . . . . . . . . . . 14 Ccmputed Compliance . . . . . . . . . . . . . . . . . . . . . . . 18 Objective of Field Studies . . . . . . . . . . . . . . . . . . . . . 21 Description of Tests . . . . . . . . . . . . . . . . . . . . . . . 21 Calibration Procedures . . . . . . . . . . . . . . . . . . . . . . 22 Temperature Sensors .................... 22 Velocity Me ter . . . . . . . . . . . . . . . . . . . . . . . . 23 Depth Sensor . . . . . . . . . . . . . . . . . . . . . . . . 23 Pond Discharge Relation ..................... 23 Description of Numerical Simulation Model . . .' . . . . . . . . . 26 Input Data Requirements . . . . . . . . . . . . . . . . . . . . . 28 Instrumentation and Communication Links . . . . . . . . . . . . . 29 Hydrothermal and Plant Operating Characteristics . . . . . . . . . 31 Longitudinal Temperature Distribution . . . . . . . . . . . _ . 32 Lateral Temperature Distribution at Downstream Edge of Mixing Zone . . . < . . . , . . . . . . . . . . . . . . 51 Vertical Temperature Distribution . . . . . . . . . . . . . . 51 Lateral Temperature Distribution ~Within Mixing Zone . . . . . 61 R e s u l ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

61 Computerized Compliance .................. 61 Thermal Plume Development ................. 69

iii .

CONTENTS

.e (Continued)

. Page Con cl u s ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Re fe rences . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 73 FIGURES

1. Location of the Sequoyah Nuclear Plant ........... 2

2. Sequoyah Nuclear Plant Diffuser Design Details . . . . . . . 5

3. Schematic Section of Diffusers and Underwater Dam . . . . . 6

4. Ambient Water Temperatures in Chickamauga Reservoir Near the Sequoyah Nuclear Plant .............. 10 5.-7. Typical Summer Temperatures at Sequoyah Nuclear Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-13

8. Boundaries of the Mixing Zone in Chickamauga Reservoir. . . 15

9. Performance Relations for Upstream Diffuser Leg . . . . . . . 19

10. Performance Relations for Both Diffuser Legs . . . . . . . . 20

11. Location of Velocity Traverse in Diffuser Pond at Sequoyah Nuclear Plant on March 30 and August 19,1983 . . . . . . . 25

12. Schematic of Slot Jet Mixing in a Stratified Environment . . . 27

13. Schematic of Computed Compliance System at Sequoyah N u clear Plant . . . . . . . . . . . . . . . . . . . . . . . . 30 14.-25. Temperature Distributions in River Channel . . . . . . 39-50 26.-31. Lateral Temperature Distribution at Downstream .

Edge of Mixing Zone . . . . . . . . . . . . . . . . . . 52-57 32.-34. Vertical Temperature Profiles . . . . . . . . . . . . . 58-60

35. Location of Measurement Stations L1, L2,-L3 for Lateral Temperature Profiles . . . . . . . . . . . . . . . . . . . . . . 62 -

36.-41. Lateral Temperature Distribtition Within Mixing Zone. . . ' 63-68 TABLES 4

1. t Frequency of Zero or Reverse Flow at the Sequoyah; Nuclear Plant, 1978-81. . . . . . . . . . . . . . .. . . . . . 8

2. Summary of Entrainment formulae - Coflowing . Diffuser . . . . 17-

3. Values of Experimentally Determined Coefficients . . ,, . . . .- 18 4'.-9. Hydrothermal and Plant: Operating Conditions . . . . , . . 33-38

.10. Comparison of Computed, Measured, and Monitored Downstream Temp c atures . , . . . . . . . . . . . . . . . . . 70 O

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INTRODUCTION

- The Sequoyah Nuclear Plant (SNP) was built by the . Tennessee l Valley Authority (TVA) on the right bank of Chickamauga Reservoir, j Tennessee River Mile (TRM) 484.5. The plant is about 18 miles (29

! kilometers) northeast of Chattanooga, Tennessee, and about 13 miles (21' i

j kilometers) upstream of Chickamauga Dam (Figure 1). The reservoir in the i

vicinity of SNP can be characterized as having a roughly rectangular main channel approximately 900 feet (274 meters) wide and 50 to 60 feet (15 to 18 i

meters) deep, depending on the pool elevation, with extensive and highly irregular overbank areas which are usually less than 20 feet (6.0 meters) deep.

, The two-unit Sequoyah Nuclear Plant has a net generating capacity of 2440 MW, and an associated waste heat load of 4800 MW t

, r 16.4 ,

x 109 Btu /hr. The heat transferred from the steam condensers to the cooling water is dissipated to the atmosphere by way of two natural draft cooling towers, to the river through a two-leg submerged multiport diffuser, or by a combination of both.

To ensure that thermal impacts of the plant are minimized, TVA is required to demonstrate - that the discharge meets thermal water. quality standards at the edge of a mixing zone. The validation of .a computerized technique for demonstrating compliance;is the subject.of this' report. Also,-

the development 'of the diffuser generated thermal plume through the mixing .

zone is addressed herein, g ~ To fulfill- these objectives the : report first describes the . intake and discharge systems, at SNP andf then followsLwith historical information on the hydrothermal conditions existing :In Chickamauga Reservoir -in .the.

, i WATTS BAR WATTS BAR DAM STEAM PLANT TRM 529 9 WATTS BAR NUCLEAR PLANT D AY TO N l ATHENS N

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ocOEE DA M NO.i f CHICKAMAUGA DAM TR M 471.0 NORTH I CHATTANOOGA TE NNESSEE C AROLINA J._ __

GEORGIA

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l Figure 1 : Location of the Sequoyoh Nuclear Plant l

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3 vicinity of the plant. A review of the laboratory model of the diffuser performance is included because it provides an understanding of the many

. modes of diffuser-Induced mixing and because it provided the framework for developing the numerical model that is the basis of the computerized compliance technique. The benefits of computerized compliance and the computer hardware and software necessary fer its implementation are described in detail. The hydrothermal conditions in existence during the field tests, the equipment used, and the calibration procedures for the instrumentation are also included in the report.

COOLING WATER INTAKE AND DISCIIARGE SYSTEMS Cooling Water Intake Condenser cooling water is withdrawn from Chickamauga Lake at a combined intake structure and pumping station situated at the end of a trapezoidal intake channel which leads from an intake embayment. An intake skimmer wall spans the entrance to the embayment. The skimmer wall leaves a clear opening length of 550 feet (167.6 meters) and an opening height of 9.7 feet (2.9 meters), with the top of the opening located at elevation 641 feet (195.3 meters) above mean sea level (MSL), approximately 34 feet (10 meters) below minunum pool of Chickamauga Lake. The skimmer wall is designed to allow withdrawal of cooler water from the lower depths of the reservoir. Because of the low elevation of withdrawal, the tempera-ture of the water entering the condensers is normally less than the tempera-

, ture of the reservoir surface water. This is particularly true during the summer months when the reservoir is stratified. .

4 Diffuser System and Controls Heated water is discharged from the. condensers or from the cooling towers directly into the diffuser pond, from which it is discharged to the reservoir through the diffuser pipes. The upstream and downstream diffuser pipes are 17 feet (5.2 meters) and 16 feet (4.9 meters) in diameter, respectively, and are installed in the approximately 900-foot (274-meter) wide navigation channel. Each diffuser section is 350 feet (106.6 meters) long and contains 17 2-inch (50.8-millimeter) diameter ports per foot (0.3 meter) of pipe length. The diffusers occupy the 700 feet (213 meters) of the main river channel nearest the plant. Schematics of the diffuser location and design details are shown in Figures 2 and 3.

Flow through the diffuser pipes is controlled by the difference in the diffuser pond and reservoir water levels; At maximum plant capacity, each diffuser discharges about 1240 cfs (35 m 3 /s) with a driving head of 5.4 feet (1.6 meters). When the plant discharges into the pond at a lower rate and the difference between diffuser-pond water level and the reservoir surface elevation drops below 4 feet (1.2 meters), a gate automatically closes the downstream diffuser and the diffuser pond is emptied through the upstream diffuser. The upstream diffuser is not gated and will dis-charge to the river whenever the pond level is greater than the reservoir level.

Located about 250 feet (80 meters) upstream of the diffuser is an underwater dam (Figure 3). One purpose of the dam is to retard the upstream movement of the warm water surface layer formed during low flow

, conditions in the reservoir. The crest of the underwater dam is at eleva-tion 654 (199.3 m), approximately 13 feet (3.9 m) above -the top of the

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14 thermal mixing zone also includes the entire Intake Basin (during closed mode) and Diffuser Pond."

. Figure 8 illustrates the boundaries of the specified mixing zone in the Tennessee River.

l REVIEW OF LABORATORY MODEL RESULTS The results and subsequent analysis of the data from the labora-tory study of the Sequoyah Nuclear Plant discharge diffuser were presented in terms of dimensionless groups of the relevant variables (McCold,1979). '

The variables deemed important to the diffuser-induced mixing are:

H = depth of the channel V = ambient velocity Qg = discharge from diffuser L = length of diffuser Ap= total area of diffuser discharge ports op = density difference between the ambient and discharge -

p, = ambient density The following dimensionless parameters deemed relevant for characterizing the performance of the multiport diffuser were functionally related by:

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[H_ V h (mg H)b

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b g 1/3 where q, is the entrainment flowrate per unit -length, mg (= Q2 /Ap l.) the momentum flux per unit length, bo (= Qo g/L ap/p,) the buoyancy flux per

. unit length, and 1, (= m /b g o2/3) is a momentum length scale.

The physical interpretation of these parameters and their relative importance in determining the diffuser-induced mixing _ is described below:

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ELEVATION Figure 8: Boundorles of the Mixing Zone in Chickomougo Reservoir I

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16

1. ge /("oH) Entrainment flow parameter. The normalization of the dependent variable g e by (mg H)b is, at this point in the analysis, arbitrary.

2. H/A m Ratio of water depth to the momentum length scale. If H/2, is o(1) or less, then diffuser momentum flux will be of major importance. If H/fm >>1, then buoyancy flu;c will dominate. Values of this parameter less than 1 indicate a well-mixed regime, while values greater than about 10 indicate a stratified flow regime.

3. V/b g 1/3 Ratio of receiving water momentum flux to buoyancy induced momentum flux. If V/bg 1/3 is greater than 1, then the momentum of the river water will dominate the discharge

, buoyancy flux, and force the effluent flow into the well mixed regime.

The precise relationship among the variables depends on whether momentum (of either the river or the diffuser) or buoyancy dominates the induced flow field. The diffuser performance in the presence of an ambient river flow may be divided into three categories, each case being defined by the 1/3 values of H/2, and V/bg ,

The complete solution in terms of coefficients that are experi-mentally determined, is presented in Table 2. The data from the laboratory experiments were used to evaluate the magnitude of the coefficients con-tained in these expressions. Based on a least-squares curve fit to the experimental data, values for these coefficients were evaluated and are

- presented in Table 3.

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18 Table 3: Values of the Experimentally Determined Coefficients C, Cg Cy t, ty Both Legs 0.40 0.40 0.22 0.24 10.

Upstream Leg 0.42 0.52 0.29 0.11 10.

l l

The expressions of Table 2 in conjunction with the experimentally determined coefficients were used to assess the impact of the thermal dis-charge at the Sequoyah Nuclear Plant. These expressions are shown plotted in Figures 9 and 10 for one- and two-leg operation of the diffuser. l COMPUTED COMPLIANCE

. The computed compliance approach to demonstrating compliance with the State's thermal water quality standard provides TVA with the dependability that is derived from using identical models for scheduling the plant operation and compliance demonstration. The temperature variation that occurs in space and time at the downstream edge of the mixing zone makes the use of two temperature monitors inadequate for obtaining a -

representative cross-sectional average temperature. . Consequently, there are occasions when the plant-induced temperature rise as predicted using the scheduling model is not in agreement with the monitored values. One-advantage to implementing this numerical model for compliance purposes is to avoid such discrepancies which can possibly result in plant derating or unnecessary cooling tower usage.

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21 )

OBJECTIVE OF PIELD STUDIES

- To validate the accuracy of the numerical simulation of the diffuser performance for demonstrating compliance with the thermal water quality standards, a series of field studies was conducted over the period April 1982 to May 1983. The objectives of the field studies were to:

1. Verify the accuracy of the computer model and demonstrate that it predicts more accurate downstream temperatures than do the two monitors located at the left and right edge of the navigation channel.

2. Measure the temperature structure downstream of the diffuser to determine the extent of the plume and its size in relation to the mixing zone.

DESCRIPTION OF TESTS To meet the stated objectives, field studies were conducted under several different ambient conditions. The range of variables possible during these field studies was determined not only by the natural conditions of reservoir temperature and stratification but also by operational con-straints of the hydropower system and the nuclear plant.

Water temperatures 'at the upstream and downstream boundaries of the mixing zone were measured at depths of 0.15, 1.0, 1.5, and - 2 meters below the water surface. This vertical string of thermistors _was mounted

. on a rigid vertical frame and towed across the reservoir using a survey l boat. The data from the eensors were sampled at 10-second intervals as i

the boat traversed the reservoir. At the boat speeds used during these

22 surveys, this sampling frequency resulted in the acquisition of approximate-ly 35 data points at each elevation. In addition to the lateral traverses,

- vertical profiles of temperature were measured using a vertical traversing bathythermograph. The bathythermograph output was sampled once per 0.5 meters. All the temperature data were processed using an on-board Nova 1200 computer. A hard copy of the data was made available through use of the Silent 700 teletype that is connected to the Nova 1200.

CALIBRATION PROCEDURES To ensure the reliability of the data taken during field surveys, calibration of the instrumentation was performed prior to and following each

, field trip. The procedures for calibrating the equipment are described herein.

Temperature Sensors The thermistors used on the boat system and those used with the bathythermographs were calibrated using a constant-temperature bath. The temperature sensors to be calibrated along with a precalibrated quartz thermometer were inserted into the bath and the temperature of the bath allowed to reach a steady state. The output voltage from the thermistors circuit and the temperatures measured by the quartz thermometer were used to generate the calibration curves which were inputted to the boat data acquisition system.

O

23 Velocity Meter The electromagnetic current meter (ECM) was calibrated in the Engineering Laboratory's towing tank. The tank is 40 feet long and there-fore permits ample distance for the towing speed to become constant.

l Faveral towing speeds were utilized and these values compared to the out-put of the ECM probe. Because the probe is capable of measuring two components of velocity in the horizontal plane, several orientations of the probe in the towing tank were necessary for achieving a complete calibra-tion.

Depth Sensor The depth measuring sensor of the bathythermograph was

. calibrated at Norris Lake since laboratory facilities were not available for calibrating to depths of 60 feet. Prior to calibration, a . steel measuring tape was connected to the cable supporting the sensor. Therefore, as the sensor was lowered into the water, known depths could be read from the measuring tape and these values related = to the output from the sensor /

circuit. This calibration information was inputted directly to the data acquisition system on the boats to be used during field tests.

POND DISCHARGE RELATION The condenser cooling water discharge to Chickamauga Reservoir is a gravity-driven system with the elevation difference between the

. diffuser pond and the reservoir being the driving force. Therefore, the discharge from the pond is proportional to the square root of the elevation difference, and the constant of proportionality a reflection of the headloss in the diffuser piping system. ,

___--- - i

24 Two field studies were conducted for evaluating the coefficients in the equation that relate flows to elevation differences. These tests were

- performed under steady-state conditions where the pond and reservoir elevation was maintained constant and the discharges to the pond unchang-ing.

An electromagnetic current meter was used to obtain the data.

This instrument utilizes the electric field generated by water moving through a magnetic field to determine two components of the velocity vector over a range of 0 to 3 meters per second. This instrument is accurate to 11.5 cm/sec. A magnetic compass indicates the alignment of one axis of the instrument to magnetic north.

At least 12 velocity profiles were measured from a small boat with

, its bow secured to a safety line spanning the cross section and anchored astern. The location where diffuser pond velocity data were recorded was about 180 meters from the diffuser inlet structure in a 140.2 meter wide cross section, Figure 11. Velocities were recorded at the surface, 0.5, and 1.0 meter depths, then the depth interval was increased to 1.0 meter as the measurements continued to the bottom. To determine the horizontal distance along the velocity traverse line where each vertical profile was measured, a transit and stadia board was used.

In addition, measurements of the pond depth were made at the locations where the velocity profiles were measured. These data sets (velocities and depths) were integrated to produce a discharge flowrate.

Pond and reservoir elevations were monitored during the test. These field

. studies were conducted for both single-leg and two-leg diffuser operation.

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O SO 10 0 ISO 200 Figure 11 : Location of Velocity Traverse in Diffuser Pond at Sequoyoh Nuclear Plant on March 30, and August 19,1983

26 DESCRIPTION OF NUMERICAL SIMULATION MODEL

- As discussed in the previous section, the relevant variables influencing the diffuser performance characteristics are:

1. Ambient velocity.

2. Ambient temperature distribution.

3. Temperature and quantity of discharge per unit length of diffuser.

4. Configuration of the diffuser.

Since the configuration of the diffuser is fixed, the variables to be considered are those identified in items 1 through 3.

In order to evaluate the river flows at the SNP site, it is necessary to use a one-dimensional, unsteady flow routing model. The results of this flow routing model are transferred to the- diffuser performance subroutine where they are used in conjunction with the other variables to evaluate the localized mixing that- occurs at each level. The diffuser plume model allows the localized mixing to occur until the plume reaches the surface or its layer of neutral buoyancy. The temperature at this point is taken to be representative of the entire plume cross ~section and is reported as the plant-induced temperature at the edge of the mixing zone. A schematic of the development- of-the plume as it rises through a density stratified environment is shown in Figure 12. The model uses localized entrainment rates that are evaluated- based on' the hydrothermal-

,- conditions of the layer being considered.

I

27 i

l Temperature Profile ty j

I ,. f "

r i

=1F T3 } T3 e e Tetume l

-) y'a vd River Flow q

Ta 1 ) )

l. 7

J l

)3

-T, -. T, C6 l

Diffuser I

, Figure 12 : Schematic of Slot Jet Mixing in a Stratified l Environment I

i 7

4

l 28 :

)

INPUT DATA REQUIREMENTS 1

- The input data required for operating the numerical simulation model are acquired and transmitted to the computed compliance computer at 15-minute intervals, and the results of the model are printed on the teletype. The data necessary for performing the diffuser performance simulation are as follows:

1. Flow releases at the upstream and downstream aams

2. Ambient vertical temperature distribution

3. Discharge flowrate of thermal effluent

4. Temperature of thermal effluent '

5. Status of diffuser gate

. The flow releases frun Watts Bar and Chickamauga are input to the flow routing model at 15-minute intervals, and river flows in the vicinity of the plant are computed at a similar interval.

Because the reservoir in the vicinity of the plant is stratified, it is necessary to measure and input to the computer model a vertical tempera-ture profile. Discharge temperature and flowrate are required in conjunc-tion with ambient temperature conditions for. the computation of the momentum and buoyancy characteristics of- the discharge. This profile is developed using temperatures measured at 10 elevations, 0.15, 1.0, ~ 1.5, and 2 meters below the. water surface, and at elevations 205, 204, 203, 200, 197, and 194 meters. The monitor used for measuring these temperatures is .

located at the intake skimmer wall.

. Since the option exists for the cooling water to be discharged through one or. two diffuser legs, the' status of the gate is required for establishing the number of legs in use.

1 i

29 INSTRUMENTATION AND COMMUNICATION LINKS

- Water surface elevations are measured at the diffuser pond and the reservoir and communicated to the Environmental Data Station (EDS) l Computer via a radio telemetry synb n. The elevation measurement at the l i l diffuser pond is made using a nitrogen bubble gage wherein the back pressure encountered in releasing a bubble to the pond is proportional to the elevation. At the intake station the elevation measurement is made using a float and potientometer. Both these elevation sensors have a manu-facturer's provided resolution of 0.3 cm.

The temperature characterizing the discharge is acquired using RTD sensors having a resolution of 10.14*C, and at the intake the tempera-

. ture is measured using thermistors that have a resolution of 0.14'C . The temperature data taken at the pond and the intake skimmer wall are trans-

~

mitted to the EDS Nova computer via a radio talemetry system. These data, temperatures and water elevations, are in turn transmitted to the Intel Computed Compliance Computer to serve as input to the diffuser perfor-mance simulation model.

Watts Bar and Chickamauga ~ Dam releases are communicated directly to the Intel Computed Compliance Computer using a dial-up modem telephone system. Measurement of flows at the dams is accomp! sh ' 'itiliz-ing differential-pressure type flow gages.

The output of the diffuser performance . simulation program is communicated to the plant operator through a hard-wired line . to the

, teleprinter in the control room. These data are sent from the control room to the Power System Control Center via a microwave communication system.

The overall system is schematically represented in_ Figure 13.

ADAS GAGES WATTS BAR AND CHICKAMAUGA RELEASES es se _

WATER TEMPERATURES s '

/ ~

NOVA POND AND RESERVOIR ELEVATIONS s INTEL TELETTPE PRINTER EDS STATUS OF DIFFUSER GATES s

, COMPUTED CWFLIANCE

< DOWNSTREAM TEMPERATURES AND AT COMPUTER s DAM RELEASES COMPUTER -

es es PRINTER .

\/

N NERAN AMBIENT TEMPERATURE PROFILE POND ELEVATION RESERVOIR ELEVATION PLANT OPERATOR Figure 13. Schematic of Computed Compliance System at SNP

31 HYDROTHERMAL AND PLANT OPERATING CHARACTERISTICS rive of the six field studies were conducted with both units of the plant in operation. The other field study was done during one-unit operation. Of the five two-unit field tests, four were performed with the

! cooling system operating in open cycle and the other during helper mode operation. The single one-unit test was carried out during open mode operation. During four of the two-unit field tests the plant was operating i

close to normal capacity (2324 MWe). However, the field test of May 14, d

1982, was conducted under two-unit operation but the power production was 1460 MWe because one of the units was cut back to 310 MWe.

The diffuser pond outflow during two-unit testing represents the

,. operation of six condenser cooling water pumps and four or five emergency raw cooling water (ERCW) pumps. On April 4,1982, there were five ERCW

~

pumps in operation whereas during all other tests there were four. The one-unit test of November 10, 1982, had three CCW pumps and four ERCW ,

pumps discnarging to the diffuser pond.

The diffuser system is designed to have two legs operating during two-unit plant operation and one leg during single-unit operation.

However, there are occasions when two units are operated on one diffuser leg and at other times, one unit discharges through two diffuser legs.

< Included in this series of field tests is a survey in which two units were i

discharging through one diffuser leg.

. River flows ~ at the plant .were computed using an unsteady. flow

- routing model identical to the one used in the numerical- simulation model.

River flows ranging from about 7,000 cfs to 39,000 cft 1were . encountered

' during the' field surveys.

32 Reservoir and diffuser pond elevations were maintained fairly steady during the testing periods. This was the result of constant dis-charges from the CCW and ERCW pumps as well as the steady releases from Watts Bar and Chickamauga Dams.

These data characterizing the hydrothermal and plant operating 1

conditions during the field studies are summarized in Tables 4 through 9.

l Longitudinal Temperature Distribution l l

The longitudinal distribution of temperature shown in Figures 14 through 25 were measured from the downstream edge of the mixing zone to the underwater dam. The locations of Monitor 8 and the diffuser are identified on these plots to provide the reader a feel for the longitudinal

, distances. The variation in the relative locations is the result of the data being acquired at different boat speeds. The average of the temperatures at the 1 m,1.5 m, and 2 m depths are presented in these figures. Most of the plots are similar, shcning the transition from ambient upstream water to the downstream plant-induced temperature. It is evident from these plots that the thermal plume reaches the surface very close to the diffuser.

Longitudinal variations in temperature range from a minimum of approximate-ly 1.2 C for the April 4,1982, and March 31, 1983, surveys to maximum 2.1*C during the September 2,1982, survey. With the exception of the April 4, 1982, test in which the temperature downstream of ~ the diffuser remains fairly uniform, there is a trend for temperatures to decrease down-stream along the centerline of the channel. In the case of the September 2, 1982, survey there was a downstream decrease in temperature of approxi-mately 2.0 C from the diffusers to the edge of the mixing zone (see Figure 17). The field test of May 14, 1982, was outstanding because of the l

i

33 Date: April 4,1982 Period of Study: 9:53 a.m. - 2:00 p.m.

- No. of Units: 2 Plant Load: 2290 MWe Cooling Mode: Open No. Diffuser Legs: 2 Diffuser Discharge: 2580 cfs Ambient Temp. Discharge Pond Lake River 5-Ft Depth Temp. Elev. Elev. Flow Hour (*C) ( C) (ft) (ft) (cfs) 0900 13.8 27.2 682.08 676.47 19,900 1000 13.7 27.3 681.98 676.46 19,800 1100 13.7 27.4 681.93 676.45 19,600 1200 14.0 27.6 681.89 676.44 19,700 1300 14.1 27.5 681.88 676.44 19,700 1400 14.1 27.5 681.87 676.43 19,700 1500 14.4 27.5 681.86 676.43 19,600 Table 4. Hydrothermal and Plar.t Operating Conditions O

34 Date: May 14,1982 Period of Study: 8:25 a.m. - 2:25 p.m.

- No. of Units: 2 Plant Load: 1460 MWe Cooling Mode: Open No. Diffuser Legs: 2 1

Diffuser Discharge: 2554 cfs Ambient Temp. Discharge Pond Lake River 5-Ft Depth Temp. Elev. Elev. Flow Hour (*C) (*C) (ft) (ft) (cfs) 0800 23.00 25.9 687.49 682.45 7300 0900 23.5 26.1 687.49 682.43 7200 1000 23.6 26.3 687.49 682.43 8000 1100 22.9 26.6 687.50 682.44 9100 1200 23.1 27.1 687.51 682.45 9000 1300 23.1 27.8 687.52 682.45 8300 1400 22.9 28.8 687.53 682.44 8200 Table 5. Hydrothermal and Plant Operating Conditions 3

35 Date: September 2,1982 Period of Study: 1:30 p.m. - 3:30 p.m.

. No. of Units: 2 Plant Load: 2265 MWe Cooling Mode: Open No. Diffuser Legs: 2 Diffuser Discharge: 2554 cfs Ambient Temp. Discharge Pond Lake River 5-Ft Depth Temp. Elev. Elev. Flow Hour ( C) (*C) (ft) (ft) (cfs) 1200 25.5 39.4 685.18 680.27 36,200 1300 25.4 39.6 685.18 680.31 38,600 1400 25.6 39.2 685.22 680.34 38,500 1500 25.6 39.2 685.23 680.38 37,500 1600 25.5 39.2 685.23 680.38 37,500 Table 6. Hydrothermal and Plant Operating Conditions i

'l

36 Date: November 10, 1982 Period of Study: 12:00 m - 3:00 p.m.

No. of Units: 1 Plant Load: 1152 MWe Cooling Mode: Open No. Diffuser Legs: 1 Diffuser Discharge: 1287 cfs Ambient Temp. Discharge Pond I.ake River 5-Ft Depth Temp. Elev. Elev. Flow Hour (*C) (*C) (ft) (ft) (cfs) 1100 15.1 33.9 683.75 677.57 39,100 1200 15.1 33.9 683.75 677.54 38,900 1300 15.0 33.9 683.75 677.59 36,200

, 1400 15.0 33.9 683.76 677.59 31,600 1500 15.0 33.9 683.77 677.60 32,300 1600 15.0 33.9 683.77 677.61 32,600 Table 7. Hydrothermal and Plant Operating Conditions 9

37 Date: March 31,1983 Period of Study: 9:30 a.m. - 4:00 p.m.

. No. of Units: 2 Plant Load: 2099 MWe Cooling Mode: Helper No. Diffuser Legs: 1 Diffuser Discharge: 2580 cfs Ambient Temp. Discharge Pond Lake River 5-Ft Depth Temp. Elev. Elev. Flow Hour ('C) (*C) (ft) (ft) (cfs) 0900 10.1 18.1 683.46 676.34 9200 1000 10.4 18.6 683.46 676.34 9900 110G 10.8 19.0 682.75 676.34 9800 1200 10.4 19.0 683.15 676.34 9400 1300 11.2 19.0 683.44 676.34 9300 1400 11.0 19.0 683.66 676.35 9500 1500 10.8 19.0 683.75 676.36 9400 1600 11.8 18.9 683.77 676.36 9300 Table 8. Hydrothermal and Plant Operating Condition's l, e I

^

38

' Date: May 11,1983 Period of Study: 7:30 a.m. - 12:45 p.m.

. No. of Units: 2 Plant Load: 2354 MWe Cooling Mode: Open No. Diffuser Legs: 2 ,

Diffuser Discharge: 2580 cfs Ambient Temp. Discharge Pond Lake River 5-Ft Depth Temp. Elev. Elev. Flow Hour ( C) (*C) (ft) (ft) (cfs) 0700 18.2 31.1 28,100 0800 18.1 31.1 *

24,300 0900 18.0 31.1 22,500 1000 18.0 31.1 23,300 1100 17.9 31.1 24,500 1200 17.9 31.1 24,900 1300 17.8 31.1 24,800 1400 18.1 31.1 24,300

Computer Failure. Data Not Available Table 9. Hydrothermal and Plant Operating Conditions

TIME IS 13252 I I I I I I I I I I I I l n I i I I g M y*

1 I

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cn

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p_ i i i i I i i

, 6 Monitort8 1 I i 1a L Diffus g ,*

I I I I I I i 13.5 LONGITUDINAL UPSTR. RUN @ RS OF CHANNEL SNP FIELD STUDY TEMPERATURES 4/4/82 Figure 14. Temperature Distribution Along Right Side of Channel

I 1

i l

l TIME IS 13:fi l i I I I I I I i 1 m I I I $ 1 I L) 16.7 -------1-------1-----m*4------5-------1-------

i i e * * , *i .i

Q g

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I i

t I $ I i I I v ig,3 . _ _ _ _ _ _I_ _ _ _ _ _ _a_ _ _ _ _ _ 4 _ _*_ , _ _ I_ _ _ _ _ _ _i_ _ _ _ _ _ _

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] I I I I I ,

H 15.1 -------8-------3------4------L-- ----I-------

q l i I I i g i I I

I W ' ' ' ' i Q I I I I I 2: 1+.3 -------'-------'------4------L------i-------

W I I I i Difduser og

g,Yg

1 f--* I '

Monitor 8 d i i i I j ggg* I I I I i 13.5 ' ' ' '

LONGITUDINAL UPSTR. RUN @ LS OF CHANNEL SNP FIELD STUDY TEMPERATURES 4/4/82 Figure 15. Temperature Distribution Along Left Side of Channel

TIME IS 13:24 5 8 i i i I i i e 24.2 - - -- J---- L----8---

g* - - - V i e : , i i

QJ 23.6 i i illie

i i t , I v i i

I i i i i e i i W 23.8 ' ' ' '

- - 8 Z - -

g, d **%endIIIp*I* - ' ' '

i i

8 i

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t i 7-----r----

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Q I I I i i i i i

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t-----------------t-----------i------

j I I I i I i Monitorg8 Diffuspr , ,

I i i i i 21.2 ' ' '

LONGITUDINAL UPSTR. RUN D CHANNEL CL SNP FIELD STUDY TEMPERATURES 5/14/82 Figure 16. Temperature Distribution ATong Center of Channel

l t

TIME IS 15:18

I I Ig i I I I T I I m as.s ------'------'------*1,---t------'-------

Q I I I I I I I I I I Q) I 1 Y# I I I a) ' ' -* ' ' '

27.+ 3 - *

t I *- Ip I I I

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{ l i I l$ $ 1 w 25.6 - - - - - - - l- - - - - - -l - - - - - - + - - - - -* - r- e ,s - - - - l - - - - - - -

b Monitor 8 I I

' I ag I I I a L Di fuser I

I I I I I i 25.8 ' '

LONGITUDINAL UPSTR. RUN @ RS OF CHANNEL SNP FIELD STUDY TEMPERATURES S/2/82 Figure 17. Temperature Distribution Along Right Side of Channel

TIME IS 13:48 I l l l I I I I I I I I o 28.8 ----- l-----I-----'----- '----- L_____l___ l (j I I I I I I i

I I I I I I l

I I I Q 1 1 W 27.+ I I I T* I I

t I I 9m e * *- I---- I i v I I, 8, g , I I I I I

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g 2s.8 g, ,-

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I I

l

' ] ** g I I I I I I a ca I I I I F_ 1 1 I I I I I I

<{ r-----r---

y 2s.2 7-----i-----i-----

bJ 8 8 ' ' ' '

Q_

t I I I I I

}[

bJ as s

n------------i------r------t-------t b I I I

Monitor 8 3 I

3 g Diff, , ,ulGIeg ,E3 g

- - - g i I I I I 25.8 LONGITUDINAL UPSTR. RUN @ CHANNEL CL SNP FIELD STUDY TEMPERATURES 9/2/82 Figure 18. Temperature Distribution Along Center of Channel e

TIME IS 13:59 I I E I I I I I I I I I m a8.8 ----- '----- 8----- I----- L_____1_____J___

(j i i I i i l i I I I

I I CD 8 ' ' ' ' 8 W 27.+ Silk- -* ' ' ' ' '

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] I

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1---- ,l------(------ r---- T---- 7---

hj i I I I I I QL I I I I I I

}] I I I i i I 63 25.6 -------I------1------t------t---*---r-----,---

I j g Monitor S I I I I I I I I 25.8 ' ' ' ' ' '

LONGITUDINAL UPSTR. RUN @ LS OF CHANNEL SNP FIELD STUDY TEMPERATURES 9/2/82 Figure 19. Temperature Distribution Along left Side of Channel

TIME IS 14:32 i i n 17,4 ________L_______1_______1_______l-______.

Q i I 1 1 I I

0) ' ' ' '

W 16.8 i t a v i i i i 1 i Q 16.2 I

1 i

3 e i i I g F--

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i W i , i

( I I I i E i

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y .ts.s --------+--------t--*----t--------,-------

g , ,*** *****ygge s,***,,,

' DiIfuser 8 '

I I I i 1+.4 '

LONGITUDINAL UPSTR. RUN 0 RS OF CHANNEL

~

SNP FIELD STUDY TEMPERATURES 11/10/82 Figure 20. Temperature Distribution Along Right Side of Channel

- . . I I

TIME IS 14:20 I I i 1 1 I I I I I m 17.4 ------

'------3------1-i--- L-----l-------

() l I

I I

,g* I*

I I

I I

I

0) i I

I ' I I I ***1

I I W 16.8 I *

$w T I I I t

v 8 I

l* I I I

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I I I I g

I I I I a

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i------i----- T----- r-----i------.

I I I I W I i

g I I I I l I I le g I

{ ,

y 15.8 - - - - - - - I- - - - - - -s - - - - - - t - - , g e m r ;

g ,; - 1 ; g - - - - -

p I I I

i gg Monitor S I I Diffuser I I I I I I i 34,4 LONGITUDINAL UPSTR. RUN @ LS OF CHANNEL SNP FIELD STUDY TEMPERATURES 11/10/82 Figure 21. Temperature Distribution Along Left Side of Channel

l 1

f I

l TItiE IS 13:09

! I I I I I I I I I I I I I I L--- 1--- 1--* 1--- d--- J--- J_____

m 13.8 ----

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,I

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1 1

I I i 1 ,1 go I g

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l b I I I I I g i I p i i 4 l

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I T--- T---

1 7---

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i

-t - - - - -t - - - - - - - -

1% i p i i 1 1 Monitod 8 I I ' ' '

a6 DifEuser I I i 1 1 I i 18.8 LONGITUDINAL UPSTR. RUN @ CHANNEL CL SNP FIELD STUDY TEMPERATURES 3/31/83 Figure 22. Temperature Distribution Along Center of Channel

1 I

TIME IS 8 59 i i i i i l i i c5 28.4 ------ '------'----- 1----- L-----'-------

i i Q i i I 3 1 - I '

CD

@ 19.8 - - - - - - - l- - - - m er -l - - - - - - f *- - - - - l- - - - - - - l - - - - - - -

v

..* 9.. .... *9......,,.; ; ;

I Lj **, i i i i :

g 18 2 i i i

) i i i I g i i

p i i 1 1 i i l 4 18.6 - - - - - -

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g i- - - - - - i - - - - -

i e i i hj I - i i 1 i i i g i gj 18.8 -------i-------i------+--m-.r-------i-------

J_ i i i , .*,,* i i i i i Monitor 8 : Diffus r i i 17.+

I LONGITUDINAL UPSTR. RUN @ RS OF CHANNEL SNP FIELD STUDY TEMPERATURES S/11/83 Figure 23. Temperature Distribution Along Right Side of Channel

TIME IS B:46 i I I gi I l l 1 1 9 . I

?

O 28.4 - -- - -- - - I - - - - - - ' -- - - - - I - - g 4 L

g- -- - -- ' - - - - - - -

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18 tgD _ *_ _ *_ _ W

_ *_ _

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g 10 2 I I I

I I

I I g I

I

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i------i----- T----- r-----I------

I I I W I I I

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1------ - - - - - t - - - - - - r- - - - - - - : - - -

p i i i i **

i i

f **

3 Monitor 8 8 a Diffu*ser 3 g

d i I I I4 17.4 LONGITUDINAL UPSTR. RUN 0 CHANNEL CL SNP FIELD STUDY TEMPERATURES 5/11/83

- Figure 24. Temperature Distribution Along Center of Channel

TIME IS 11:54 i i q i i i i I I I i I a 28.4 ----- d---- J______I______l__ ____L_____l___

LJ ' ' ' ' ' 8 I I I I I i CD 8 I I I ' 8 QJ 13,g . _ _ _ _ _* N_*e.* ,,qeedoges. _ _ _l_ _ _ _

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i i i i

i i

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I eI g

[ I I I I I T**

<( l i I I I I gg g 18.6 -----

7---- ,----- -----

----- r---- T---

bj i i I I i I Q, I I I I I I

}[ t i I I I I hj 18.8 -------t------1------1------1------t-------t---

F- 1 I I I I I Mpnitor 8 I i i Diffuser i dI '

I I I i I g7,4 . . . .

LONGITUDINAL UPSTR. RUN @ LS OF CHANNEL SNP FIELD STUDY TEMPERATURES S/11/83 Figure 25. Temperature Distribution Along Left Side of Channel

51 apparently anamolous downstream temperatures. The temperatures down-stream of the diffuser are cooler than the ambient in the surface layer.

4

. This anamolous temperature pattern is the result of the thermal stratifica-tion of the reservoir during this test. As will be shown in another section of this report the surface to bottom temperature variation during this survey was approximately 9 C. As the thermal discharge plume moves toward the surface, it entrains the cool bottom water which it carries to the surface because of the excess momentum of the plume. Eventually the plume sinks to its layer of neutral density and the surface layer reverts back to temperature similar to the upstream ambient.

Lateral Temperature Distribution at Downstream Edge of the Mixing Zone

. During most of the field surveys it was observed that surface layer temperatures were somewhat higher on the left side of the channel.

In addition, the temperature variation from point to point across the section was as large as 1.0*C. Added to the spatial variation are the temporal changes depicted in Figures 26 through 31 in which the vertical average of the tcmperatures at 1.0 m, 1.5 m, and 2 m are presented. It can be observed from these figures that though the general tendency is for down-stream temperatures to increase with time, there is a certain randomness to the temporal changes at any given point.

Vertical Temperature Distribution Because of the crucial role of temperature stratification on inter-

.. preting field data and the need for this as input to the numerical simulation program these data were necessary. The vertical temperature structure encountered during the field. surveys is depicted in- Figures 32 through'34.

^

--_-__._._L-___--_-._--_.._ . _ . _ - - _ _ - - - . . _ _ . _ .

8:54 a.m. --

12:53 p.m.

10:44 a.m. --

1:38 p.m.

11:45 a.m.

/

17.3 O--/ A ' s - - - - :- - - - - - r- - - - - - r- - - - - r - - - - - r - -

a o

sW s /s ,k '/\ s 's i i y'-::_5^

i e i g ,i\ p + , 's \ s I f

, / ---- .., ' ' s

./ ( j,, I s

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\----t

-t^- e- - - - - -- ---

i--

"c 16.6 ----- ---- -

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\

, i u i i ,

i ,

-r- -

W 8 ,'-J. 8 ,,' - '-J/ \ ', 8 8 A. l 'l ,,-

' \ !

7-

/----i' -~ . -\.

t,.Ts - i i --*-----,--

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1 s \/ (1s f.,T s I /

t\

I \

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E : / i '\

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+-----4--

1-- 15.2 - - - - - - ' - - - - - - - \-s - y-/ - - - - -\, _-s -

a 5

a i : 's. / s a --r I I I I I I I I I i 1 8 14.5 8 300 600 900 1200 1500 1800 DISTANCE FROM LEFT BANK Cfeet)

DOWNSTREAM CROSS-SECTIONS 4/4/82 Figure 26. Lateral Temperature Distribution at Downstream Edae of Mixina Zone i

2+.0 8:53 a.m. - - 12:14 p.m.

11:01 a.m. --

12: 49 p.m.

11 : 2 4 a . m .

23.5 - - - - - - - - - - -

- - - - - - r- - - - - - r- - - - - - r - - - - - r - -

O l I l i i -

{ f i a i , a I i

\ i >

03 I I .I , I ' ), 3 e 1 '

i i 's ,

q ,i s,' i

$ -+ a---4

" a3.0 '^ /xi-i- - - - '- i',4 ,'s, 7 A ' i-f9,4_',<s,i

,,dii -<' - ' \ 's

, ' s i

. i e

, '.' / N x, ./((' N s i

s nv,i e : / g' < 3

,\/ u.sp<n, ,i;,- /sf / \ i' i

\v/V'u i sT se , .,

a s

\</

, d - ,i - - - - - - i - ' -

,s N '

Qaa.5 -

'- - v' ,_7 ' , i- - - - - - +i - - - - - +i - -

x s:'4, i .

N i i ,i w -

. -i. ,

\~

,,i, /i '

, .., ' . , $ ' ~. . . i sl i I i ~ '

1

} } ,_ .

\

i... j w ,i 8

' s . f 'i '/

"---s N.

m,-----+--..-+--

s aa.e - - - -s ,, ,- - -i; .-- .

', s g-i

, .1- ,

il ./

i i

s,-

~' i w/ , - i

' , ' .. i, ;

i i' i , i i i i i i i 21.5 O 300 600 900 1200 1500 1800 DISTANCE FROM LEFT BANK C f ee O ,

DOWNSTREAM CROSS-SECTIONS 5/14/82 ,

Figure 27. Lateral Temperature Distribution at Downstream Edge of Mixing Zone

28.5 1:31 p.m. --

3:02 p.m.

1:41 p.m. --

3:28 p.m.

1:58 p.m.

28.8 ---------------------------------------

1 I I I I I

^ 't i I I I I

! I I I I I p27.5 y,a r!7,s'- --/\ ' s s

'- - - - - - y - - - - - f - - - - - f - - - - - j - -

y ' ,j :5 I

\ g, k [, \/ , ,/

3 y27.0 - \,y ', - -l. f /* M,' y g !'/,,f s- - g - - - - - f - - - - ' - -

D g' ' <! \ / - i

\ : :

s ,

, , t -

'1, - evv . T. , ,

g #.

<c i . ,l s,,- - -

g ,

- I - \ i to 26. 5 ----*in-----

' , 'l: -----

i

' ,r -i- 77-----r--

0- '

i i : i i i h 8 8 8 I, \\(s'\r-gh

\ '

8 9 s s s '\,

., s -

n 26.0 - - - - - - i - - - - - - :- - - - - - r- - - - - - V

'g --%,r ll f - - - - - -r - -

i : : i~s -

i I I I I I I I I I I I 25.5 0 388 600 908 1200 1500 1800 DISTANCE FROM LEFT BANK ( f ee O DONNSTREAM CROSS-SECTIONS S/2/82 Figure 28. Lateral Temperature Distribution at Downstream Edge of Mixina Zone L

I s

17.5 11:51 a.m. --

2:48 p.m.

1:26 p.m. --

3:23 p.m.

2:11 p . .m .

17.8 - - - - -

- - - - - - :- - - - - r- - - - - r- - - - - r - - - - - r - -

U b l l l l l l

\

3 } I I I I i I W { f 8 I I I I 3 16.5 jw -:,(\ -

i- - - - - -i- - -

l t

-r-----r-----t-----t--

i i i E o ..,

\ ,

i i W / ., ., I ,

I i

% k 't t

' ) /, si ' ' ' ' $

16.8 -

- - -i ' s ,,- -

'?j 8- - - - - - I- - - - - - ----- '-

M w

.\.

I i

s' \

4, 4/

fc/

'l I i

i i

I i

n. 3

,.j 1 b , : _e )n,i.s , , ,

E g

/ ',j '- i a s is.s ' I '

4-s s- - s -

o--

< 73 - 'i- - - - -4}>sYk'#\'w +i -----4--

V'7 - i fl ,

\/ i i ,

.-. A. .s

'"'s i ,

, , ,N/ , \./ , ,

15.8 ' ' ' ' '

8 300 600 900 1200 1500 1800 DISTANCE FROM LEFT BANK (feeO DONNSTREAM CROSS-SECTIONS 11/10/82 Figure 29. Lateral Temperature Distribution at Downstream Edge of Mixing Zone

11:04 a.m. -- 12:58 p.m.

11:14 a.m. --

3:03 p.m.

12 : 3 8 p . m .

~

12.9 I ' s, " 1 ( l I m;

f.J -

I 's i e s 'I : I ..

i I I ,

1 I f I I I i

m 12. 7

'------'1.',r- '---- 1---- 2--

e f i- p* I i i I i 7 8

/

f 3- ' i gy \hti , / ,- \' ,J, g 3 .

~ '

i I i I V- w 1g.g l l : \g j.' j' -

l'. l/ ll_\ . ,-'4. 4 jg \l I

.. __ L:7 ,j. }/_,;.j

. 8 tr i I m K

\Y

('f I' . _ _ . .

0 4 / e

. )hl \/ :g,,',L/\N I g ./. ,

en w 12;3 j--j. --s. gs-4-I -

. ./.- -

I r---, s s j I r-4/--- T--

1 ' '

I I I I I I

' E --/ I I I y I ,

I I F. I I I I I i 12.1 - - - - - - l - - - - :- - - - - - r- - - - - - r- - - - - - r - - - - - r - -

I I I I I I I I I I I I I I I I , I i 11.9 .

O 300 600 900 1200 1500 1000 DISTANCE FROM LEFT BANK CfeeO .

DONNSTREAM CROSS-SECTIONS 3/31/83 ,

Figure 30. Lateral Temperature Distribution at Downstream Edge of Mixing Z'one

22.8 7:49 a.m. -- 11 : 48 a . m .

8:41 a.m. --

11:47 a.m.

11:04 a. p----------------------------

21.5 ---------

1 I I I I I

4 I I I I I i O

21.0 ------t------------F----->-----+-----4--

3 j' " ~ '.,8 ,.

t -

1 I I J W ,/ I'. , ',,

. (*', I I I I "13 v

g

.'g ',

g g g g 28.5 7'- -- i--------A,- ,

i i i W l 8 8 ',

. I I I I

% I A I % I

.I I I I m h 28.8 -! j~I hh-=- l e 1 y ' - ~

' - ': *-w-k---- 2-- l

' % 7 [, =x1 r

3e -

~ s n 4

x s 1 I s ,.s, W '

. .I i 4\ -

! ,- S , y

1 19.5 ' 1- - -

- - - - - r- - - - - c - -

E ."-^ ^ r =~r--N-A s r - -

W y s/~N %g. ,.

g T -

,v-- '"

g ,

b i ! \/ \.M g

~

3 8 i ['

.g I NA '--- ' '

19.8 - ---

o, I e i i 4 T- :

i i .i i N,. i "g j \ i i

I I

n a

\j \ s 1e.5 -

\

8 388 688 988 1288 1588 1888 DISTANCE FROM LEFT BANK C f ee O l

DONNSTREAM CROSS-SECTIONS S/11/83 Figure 31. Lateral Temperature Distribution at Downstream Edge of Mixing Zone

58 B

~~

- t8- -

!"a &,, l' i n .*,,*.. '

s.

e e 28 - - . '..*

+ l.

ll 3 as - -

j

a. ,

w .-

o '

48- -

58 !

13 14 15 l

l TEMPERATURE (dee C)

d. UPSTREAM TEMPERATURE PROFILES +/+/82 1

q.

e ~'

1! E E;"; .....

a.=... '...-

1g. -

M t

! e

e. aa - -

,l V

f 6 se - -

a.

w .

i o ,

l

+a - - {

C

- 58 ! ! ! ! !

16 18 28 aa g4 yy TEMPERATURE (dee C)

UPSTREAN TEMPERATURE PROFILES. S/1+/82 Figure 32. Vertical Temperature Profiles !

59 i

' ~

12sSS Neen ,

1ees p... :p

--- asse p.m. j 18- - /

O

,I as -

v-

? a8 - -

G.

tu Q

q- -

1 58 !

2+ 25 28 TEMPERATURE idea C)

. UPSTREAM TEMPERATURE PROFILES S/2/82 E \

lisse m.m.

snee p.m. ,

4889 p.m.

18- -

3 I as - -

? se - -

o :

+s - -

i i

. 58 ! !

13 1+ 15 18 TEMPERATURE (dee C) l UPSTREAM TEMPERATURE PROFILES 11/10/82 Figure 33. Vertical Temperature Profiles-l --

60

. B I E *:":

+, ,,...

....'-~~~ [ ,

>- 1g- - . V.... - .

2 l I

e 28- -

' + a V

1

H 38 - -

A W

o - ,

I 4g . -

se ! ! ! !

)

B 9 18 11 1y 13 TEMPERATURE (den C)

. UPSTREAM TEMPERATURE PROFILES 3/31/83 8

11ess ....

18- -

O e

e BB - -

+ i l

z l

> 33 -

{

L ,

w :

o

+8 - -

1 i i I

' 58 - - '

i is 17 18 is 28 )

TEMPERATURE (deg C)

UPSTREAM TEMPERATURE PROFILES 5/11/83 Figure 34. Vertical Temperature Profiles - ;

1

61 The field studies of September 2,1982, and November 10, 1982, may be characterized as unstratified, whereas the others were conducted

. under varying degrees of stratification. The stratification on April 4, 1982, and March 31, 1983, is the type that is established and destroyed on a daily basis in response to solar radiation. On the other hand the strati-fication encountered during the May 14, 1982, and May 11, 1983, surveys are well established and not likely to be destroyed during nighttime con-vective cooling.

Lateral Temperature Distribution Within Mixing Zone Lateral temperature distributions within the mixing zone were measured during the -field studies of March 31, 1983, and May 11, 1983.

Measurements of lateral temperature distributions were made at three stations (L1, L2, and L3) located in the mixing zone as shown in Figure 35.

Station L1 is located at the downstream edge of the mixing zone, L2 is approximately 1100 feet downstream of the diffuser, and L3 is roughly 500 feet downstream of the diffuser. The data, presented in Figures 36 through 41, show the average of the temperature at the 1 m,1.5 m, and 2 m depths. The purpose of these measurements was to provide insight into the development of the plume within the mixing zone. These data in conjunction with the longitudinal temperature profiles shed some light on the areal extent of the plume as it moves through the mixing zone.

! RESULTS l' 1

! Computerized Compliance l The data obtained during the field studies were used as input to the computed compliance simulation model. The data for the upstream i

~ ^

\l

-:e: I 1

\

I g o I S

\ \%E

\ \$$

\Ng% M

\ P

\ \9c L

\ \%$

\

SEQUOYAH NUCLE AR . PLANT..

. .;;({:

\ y. / O g..

,/,/

- /

Ls... s, t - p DlFFUSERS' '

-- _ N- ,,-

y '

N + TRM 484 .,,,,

L3.: 's

AXIS OF r y s__- .

SKIMMER WALL UNDERWATER DAM .;1 c:.

Figure 35: Location of Measurement Stations Li,'D, L3 far Loterol Temperature Profiles

i i

l t

14.0

--- 11:34 a.m. -----

3:05 p.m.

12:23 p.m. --

3:37 p.m.

13.5 ---------------------------------------

I a

,' / \n s

's, ,/ \, s\

l I

] I I

, , ,p

,1

~ s, ,<

. L.5 I CD13,g - - - - _ .

I_ _ _ _ _ _I_ _ _ _/2 w,J L _g_j _ _ '.,

':' 1. _ _ _ _ _ 1 _ a q _ _ .1 _ .

,! / .~~~~" -- ,

w 1 ,

, .y / '

,f" ,, 1 I

%'\

's\ l

' L ,,#

W I - ~ I I /~ s

~~

T. 12.5 ,-------- -,' - * ' ' f ~b.\s -

,e 1- I .----l

1 1 cn

-3 ~~ -A l , ". I I w

g j 3 I 1 ,__,/ I I I l l 4

Q: I I I I i w 12.0 - - - - - - - ,4' - - -----------

g-- ,

3 1 -

/

i l I l :

r y _,_.,

-4 p" I I 3

I i F- .

I I i e i 11.5

- - - - - - i - - - - - - : - - - - - - r- - - - - - r- - - - - r - - - - - , - -

I I I I I l

.I I I i l g i I i I g i 11.0 ' ' ' ' '

8 300 600 S00 1200 1500 1800 DISTANCE FROM LEFT BANK CfeeO DOWNSTREAM TEMPERATURES MARCH 31, 1983 Figure 36. Lateral Temperature Distribution at Station L3 C _ _ . _ _ _ _ _ _ _ _

13.5

--- 11:48 a.m. --

2:26 p.m.

12:12 p.m. - -

3:13 p.m.

1:08 p.m.

^

13.1 - - - - -

- - - - - :- - - - - , c : - - e ' :- ,.- - - r - - - - - r - - l t 3 l

'4

's t l

O i i i L 4

. s -

.cn i , , . s., / b ' 8 I I s, - 8 W t l, b i I I I

/h[ ' ~

] 12.7 -N_ ,A{-t --- - - - - :-\- -

. t- - - - - - t-

, - V, , .- t - - - -

7 - -

j 5, g i ' . <......, ,

tr i /\,, rN \ i i i E

\ / x.3- f ~/ '

.t .

3 . .......w.

~,- .. . . , . . ,s/

n a s H / '

4 12.3 - - - - - - : - - - - - - - - - \ - A, -i - - - - F - - - - -+-----*--

I \/

Oc : I s i W \ s a' i '# - r' (1. i \ / -r E

g i I e

r\\

\/

-1N v I i i

p 11,3 _ _ ._ _ _ i _ _j_ .~. _ i _ ,,, _ _ __s_____w_____+_____4__ ft '

/'W N c' I

s I

a n 1

1 I t I L 8 I I I I I I I I 11.5 ' ' '

8 308 688 900 1200 1500 1800 DISTANCE FROM LEFT BANK CfeeU DONNSTREAM CROSS-SECTIONS 3/31/63 Figure 37. Lateral Temperature Distribution at Station L2

-- 11 : 0 4 a . m . -- 12 :58 p . m .

11:14 a.m. --

3:03 p.m.

12:38 p.m.

12'S ---------- '------------------------

U J-\ n

' p

s ,.~.,

t s

,J s

s pa m 12,7 y - - ' - - - - -

8./ 'y !. - I f~ ,~'

- L--_- L-----.1_.

E '

, , , 'J -l i T I[

N A I l ,

lU(.s I \' ! \. /in / --k

,N' '---- '--

N12.5 - I- , _ }_ y g.. .

\ } l- A,;,f ls 'f l s \ '- - - - -

^

c.? g \/,i,'.. # ., 4 _/ \ '

R g j fVl f N y -

r. /. ./ :- - - - - :

N l

l w 12.3 j i

'4 - y- - - r - - - - r - - - - - r - -

D. -

: : : i i I J , , , , , ,

wp. : :

i 12.1 - - - - - - : - - - - - - : - - - - - - r- - - - - - r- - - - - - t - - - - - t - -

3 I I I I I I I I I I I I I I I I i 11.S S 300 600 S00 1200 1500 1800

' DISTANCE FROM LEFT BANK Cfeet)

DOWNSTREAM CROSS-SECTIONS 3/31/83 Figure 38. Lateral Temperature Distribution at Station L1

21.0 8:06 a.m.

9:59 a.m.

1:14 p.m.

I I I I I I 20.5 - - - - -

- - - - - - : - - - - - - r- - - - - - r- - - - - r - - - - - r - -

e i i l ./\ i : i i l ,!

~

I i t

e '\ ',.3

/l .

I i i i i \r.

m e i i . . . /:I

^

t '. /l i i

" 20.0 - - - - - - :i - - - - - - i-i - - - -//-b- 4!

'O --

A/y4.--+-----+--

l'. iI i y n,,------- ,

s / /..U l s a } '., a w ...... 1 ',

~ s ,

-l-

}\ s :..-r e Nl~. '., I ,/ / a s ',.a l s f Ti -/ ,r h - > - - - - - * -

- -(g -J' + - -l /- - - + - -

g 19.5 - - - - - - - - - -

's / i : . \ ., i W i I/ I l :. ! I G- x .i s a \ \n l s E /i i / i

'1 i -

bJ <

- - i - - - - / - i - - - - - - - - - - - - - - j- ' 'Y

~

F- 19.0

,1. .

s e n ,,1 \,." ~--..t. .k ,

a s s ., a s

a l' i i I I '8 I i 10.5 O 300 600 S00 1200 1500 1800 DISTANCE FROM LEFT BANK CfeeU DOWNSTREAM TEMPERATURES MAY 11, 1983 Figure 39. Lateral Temperature Distribution at Station L3

l l

l 21.8 3:50 a.m.

12:37 p.m.

I l I I I I 28.5 - - - - - -l- - - - - -l- ---"-----h-----+-----4--

I l I I I I

5 8 I I I I I I I I I I I m 28.8 -----' ---- LA--- '---- L-----L--

. '- A. .

I I I I J-s'\, ,I I

l

/

A,

\l t

/ .,]l -

/-

I 1

I I

d\=f',---

'

1

$19.5 - - - - -

,/- - - - - e-

t -

g a .l l I i.j I t , 8 F- ,/ I I I

/

I 'I I I g* 'N- 1 I I I k i I to 19. 8 - - - -

l - - - - - l- - - - - r- - - - - r g 8 ---r--

g i I

i I

I fy l '

i I

g F. I I I I I i 18.5 - - - - - - i - - - - - - l- - - - - - :- - - - - - :- - - - - r - - - - - S - -

1 I I I I I I I I I I I I I I I l I 18.8 '

B 388 888 988 1288 1588 1888 DISTANCE FROM LEFT BANK Cfee0 DONNSTREAM CROSS-SECTIONS 5/11/83 Figure 40. Lateral Temperature Distribution at Station L2

22.8 7:49 a.m. -- 11 : 40 a . m .

9:41 a.m. --

11:47 a.m.

11 : 04 a.m.

21.5 ---------------------------------------

1 I I I I I

% i B l i I I U

21.0 ------'------8------b------6-----6-----4--

m / ~ ~ \.I f', I I 8 8 8 T

W / t, I/' ,

'g I I I I g 'g g , g ,

v '

28.5 --------------A,-- : ,

I F---- T---- T-"

hj l I i \, I I I I Z I A B % I

.I I I I m P 28.8 -l OM9- A ' 'k 'Y'- ~

i

' : 2 ' '- -

- ^I - - - - 1 - -

~

4 f/,. . 7 s \l '1 I g 8 I s% I I .I I I 4\ ' l i

'- %~ s.m---i------r---.s-e---/e %-M ';V Lij

/ '

o-r 1s.5 r --

~

, q. .. , -~ , ,

k I I N %

I I I

l i I

+

*\

19.8 ,

'-" # t, I l.

g-I --

, , g I I I i i I I I

\v "\ 1' l.\ l I

I

\; '

18.5 ' '

8 388 688 988 1288 1588 1888 OISTANCE FROM LEFT BANK ( f ee U DOWNSTREAM CROSS-SECTIONS S/11/83 Figure 41. Lateral Temperature Distribution at Station L1

69 temperature profile were obtained from the instream temperature monitor located at the intake skimmer wall. Discharge temperatures were measured

, by a monitor located in the diffuser pond close to the diffuser intake structure. In addition, field checks of the pond temperature were usually done prior to conducting the field surveys. Releases from Watts Bar and Chickamauga Dams were obtained from the records at the Met Tower. The results from the computed compliance simulation model and the temperatures measured by the present monitoring system are presented in Table 10. In addition, the lateral average of the temperatures measured during the field surveys (and considered to be most representative of downstream tempera-ture conditions) are included in this table for comparison. Prior to laterally averaging the measured temperatures, plots of the downstream,

. lateral temperature profiles were reviewed with the purpose of identifying the extent of the plume.

Thermal Plume Development When the hydrothermal conditions permit the plume to rise to the 4

surface it was observed, from reviewing longitudinal profiles of surface temperatures, that the point at which the plume intercepts the surface is' very close to the diffuser pipe. In some cases the plume extended upstream of the diffuser pipe. The extent of this upstream excursion is 1

dependent on the prevailing ambient flow conditions. On September 2, 1982, and November 10, 1982, when the flows were at their. highest, we find that the plume is driven downstream of the diffuser due to the

. momentum of the river flow.

Under conditions of strong stratification as exhibited during the field study of May 14, 1982, the plume overshoots its layer of neutral

70 TABLE 10

, Comparison of Computed, Measured, and Monitored Downstream Temperatures Test Date and Time T Tmonitor 11 Tmeasured T computed monitor 8 4 April 82 9 :00 - a.m. 16.1 15.9 --

16.4 10:00 a.m. 15.7 15.6 15.7 16.6 11:00 a.m. 16.2 15.6 15.9 16.5 12:00 m 16.3 16.2 16.5 16.5 1:00 p.m. 16.4 16.4 17.0 16.7 14 May 82 9:00 a.m. 22.8 22.1 22.1 -23.5*

10:00 a.m. 22.9 22.1 23.1 23.6*

11:00 a.m. 23.0 22.4 22.1 22.0*

12:00 m 23.5 22.6 22.4 23.1*

1:00 p.m. 24.7 23.5 23.1 22.6*

2 Sept 82 2:00 p.m. 26.9 ** .26.9 27.1

, 10 Nov 82 1:00 p.m. 16.5 15.1 15.8- 15.8 2:00 p.m. 16.3 15.1- '16.0 15.8 3:00 p.m. 16.4 15.0 16.0 15.8 31 March 83 11:00 a.m. 12.2 12.4 12.4 12.4 12:00 m 12.7 12.7 12.5 12.5 1:00 p.m. 12.4 12.5 12.5 12.5 2:00 p.m. 12.5 12.6 12.7 12.5 3:00 p.m. 12.9 12.7 12.7 12.5.

11 May 83 11:00 a.m. ** **- 20.4 20.1

*Due to thermal stratification the plume did not surface,-Monitor 13.used. *

- Computer problem; data unavailable.

71 density bringing cool bottom waters to the surface. Eventually, the plume plunges to its density layer and flows downstream undetectable in the

> surface layer.

The plume spreads as it proceeds downstream. Lateral profiles of the surface layer temperature indicate that the plume is approximately 1500 feet wide as it exits the mixing zone during two-leg diffuser discharges.

During one-unit, one-diffuser leg operation, the plume width is approxi-mately 900 feet at the downstream edge of the mixing zone. However, the plume grows to about 1200 feet when two units of the plant are operated on one diffuser leg. Considering that the width of the mixing zone is 750 feet, it is evident that under all operating conditions the plume exceeds the boundaries of the mixing zone. However, in all cases sufficient mixing was accomplished that the plume temperatures were within the Tennessee water quality standards.

CONCLUSION The results presented in the previous section indicate that the instream monitoring system as well as the computerized method are adequate for obtaining a representative temperature at the edge of the mixing zone.

The largest discrepancy between the computed and measured temperatures occurs for the test of April 4,1982. This variance with the measured of f

0.96C occurred during a survey when there were rapid transients in the downstream temperature. Referring to the lateral temperature distributions

. presented in a previous section one . observes substantial amounts of cool water to the right of the plume that accounts for the lower values of the ,

laterally averaged temperatures. This phenomenon 'is particularly evident

l 72 during the early hours of the field study. However, the average I discrepancy between the measured and computed downstream temperatures

. was 0.22 C, whereas Monitors 8 and 11 showed differences of 0.44*C and 0.36 C, respectively. It can be concluded, therefore, that the computer-ized method is a more appropriate technique for demonstrating compliance.

In light of the favorable comparison between the computerized method and the laterally averaged temperatures it would be desirable to have the computerized compliance technique implemented at SNP. This approach for demonstrating compliance with thermal water quality standards provides TVA the dependability that is derived from using identical models for scheduling the operation of the plant's cooling system to meet standards and also to demonstrate compliance. This compliance procedure will minimize the number and duration of thermal noncompliances. In the past thermal noncompliances occurred despite a diligent effort on the part of the plant operators to mitigate the problem. Though corrective action is usually taken prior to a thermal noncompliance, the stage is already set for one to occur at a later point in time. The use of a -model, as is proposed here, allows the operator to anticipate undesirable thermal conditions and to implement changes that will ensure compliance with thermal water quality standards in a timely fashion.

The longitudinal and lateral temperature profiles indicate that, though the thermal plume extends outside of the mixing zone, compliance I

with the applicable thermal water quality stand - rds is achieved. In addi-tion, it was discovered that during periods of strong thermal stratification in the reservoir the plume brings cool bottom water to the surface as it overshoots its layer of neutral density. Eventually, as the plume dissipates its momentum it sinks to its density layer and proceeds ' downstream indistinguishable from the ambient.

73 i

REFERENCES d

McCold, I.ance N., March 1979, "Model Study and Analysis of Sequoyah o Nuclear Plant Submerged Multiport Diffuser," TVA Division of Water Management, Water Systems Development Branch, Report No. WR28 45-103.

McIntosh, Dave A., Billy E. Johnson, and Ellen B. Speaks, October 1982, "A Pield Verification of Sequoyah Nuclear Plant Diffuser Perform'ance Model: One-Unit Operation ," TVA Division of Air and Water Resources, Water Systems Development Branch, Report No. WR28 45-110.

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