ML17318A679

Summary Rept Comparing Thermal Plume Measurements W/Modeling Predictions

ML17318A679
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Site:	Cook
Issue date:	03/31/1980
From:	ETA ENGINEERING, INC.
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ML17318A680	List: ML17318A679 ML17318A681 ML17326A659
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NUDOCS 8004150520
Download: ML17318A679 (77)

Text

INDIANA 8( tlICHIGAN ELECTRIC COMPANY DONALD C.

COOK NUCLEAR PLANT, UNITS 1 AND 2

)

SUMMARY

REPORT COMPARING THE D.

C.

COOK THERMAL PLUME MEASUREtiENTS 0/ITH tlODELING PREDICTIONS ATTACHMENT 1 AEP: NRC: 0170A Prepared by:

ETA Engineering, Inc.

415 East Plaza Drive Westmont, Illinois 60559

tlarch, 198O Dochot 4 Wo-3 l5 EAJ UMQ Co!ltfcl @ S oOAs D5df Date~-~6 of Docrrmeab RE8KQOAY DONEI'H.E 8004'0

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TABLE OF COHTENTS

l. 0 INTRODUCTION.

l. 1 Technical Specification Requirements

l. 2 Objectives of This Report 2.0 SUh1MARY OF THE MOHITORING EFFORT

2. 1 Monitoring-Periods 2.2 Summary of Monitoring Results

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3 3

2.2. 1 2.2.2

'2.2.3 2.2.4 "2.2.5 Plume Areas, Midths, and Volumes Plume Thickness Centerline Temperature Decay Seasonal Variations Areas of Influence 5

7 7

12 13

2. 3 Ambient Conditions 2.3. 1 Ambient Lake Temperature 2.3.2 Ambient Lake Currents

2. 3. 3 Stratification 3.0

SUMMARY

OF MODELING EFFORT

3. 1 Hydraulic Model 3.2 Mathematical Models

3. 3 Modeling Results 4.0 COMPARISON OF'FIELD DATA WITH PREDICTIONS 4.1-Plume Areas 4.2 Centerline Temperature Decay Rate 4.3 Plume Depths 4.4 Plum Volume 4.5 Region of. Influence

5. 0 SUMh1ARY REFEPEHCES APPENDIX

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LIST OF FIGURES Excess Temperature vs.

Distance (August-September, 1978)

Excess Temperature vs.

Distance, (November, 1978)

Excess Temperature vs.

Distance (July, 1979)

Region of Lake Influence by D.

C.

Cook Units 1 & 2 Discharge Lake Temperature Data (6/22/78-8/20/78)

Lake Temperature Data (6/22/78-8/20/78)

Lake Current'ata Plots

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10 15 16 20 Lake Current Data Plots Current Directional Persistence (1979)

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21 23 Hydraulic Test Data (9/2/72, 9/22/72, 10/2/72, 10/11/72)

Hydraulic Test Data (11/16/72, 11/20/72)

'ydraulic Test Data (ll/17/72, 11/21/72)

Hydraulic Test Data (9/8/72, 9/15/72, 11/15/72, 11/22/72)

Excess Temperature vs.

Distance (July, 1979)

Excess Temperature vs.

Distance (August-September, 1978)

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Excess Temperature vs. Distance (November, 1978)

Region of Lake Influence by D.

C.

Cook Units 1 8: 2 Discharge 33 34 35 36 37 38 39

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LIST OF "TABLES Paqe Summary of Plume Areas, Midth, and Volumes J

Predicted Plume Areas vs.

Lake Current Speeds 29 Predicted Plume Temperature and Velocity vs.

Distance 29 Predicted Plume Areas,

Depths, and Volumes 30 Predicted Maximum Extent of Plume (derived from a variety-of current conditions) 30

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1. 0 INTRODUCTION Techni cal S eci ficati on Re ui rements The Environmental Technical Specifications~

for the Donald C.

Cook Nuclear Plant Units l. and 2 state, the following objectives for monitoririg the lake

water, temperature in the region of the plant:

(1) determine the thermal characteristics of the.lake within 'the defined study area, (2) determine the

size, shape, and location of the thermal plume under different wind and lake current conditions, and (3) determine if the thermal discharge is in com-

-pliance with the thermal criteria of the Hichigan Mater Resources Commission.

These Technical Specifications called for monitoring the thermal plume while the two units are operating at, at least, 75%%uo of rated power during four study periods scheduled as follows:

15 February - 15 i)arch 15 April -, 15 May 15 June - 15 September 1 November - 1 December Each study period was to consist of a minimum of five sampling days with two plume resolutions made during each

day, dependent upon seasonal weather condi-tions.

The monitoring effort was to determine (1) the area within the 630F

isotherm, (2) location of the plume centerline, (3) rate of excess temperature

decrease, (4) plume width, (5) thickness of the

plume, and (6) depth of the winter, sinking plume.

The Technical Specifications required the data to be displayed as isotherm diagrams showing the area enclosed by the 630F isotherm.

The data from these studies were to be used to verify the analytic and/or hydraulic models used to predict the size and location of the thermal plumes.

The lake current data, as measured by drogues and in-situ current meters, were to be correlated with the meteorological data.

1.2 Ob ectives of This Re ort The primary objective of this report is to provide a comparison of the field data with the analytical and hydraulic models used to predict the thermal

IIg plume characteristics.

A second objective is to summarize the monitoring effort and to demonstrate why, even. though'he winter monitoring period. vIas N

missed and the spring monitoring effort was delayed until early July 1979, the effort is adequate to validate the model predictions.

I I

wind and-the water so that a given wind velocity will create larger

waves, and more rapidly, than when the air is warmer than the water.

Furthermore, winds out of the north (northwest to northeast) are usually more predominant during the fall and winter.

Because of the long fetch for winds from this direction, adverse wave conditions prevail frequently.

The east shore of Lake Michigan is more difficult to work than is the west shore because of the predominating wind and wave conditions.

No thermal plume maps were obtained during the winter period because of lake ice.

Monitoring attempts were initiated on March 27, 1979, in anticipation of the dissipation of the lake ice.

Ice and weather continued to be a problem during this period until Unit 1 was shut down for refueling.

On the only day that monitoring could be attempted, the monitoring equipment became erratic because of the extreme cold.

No plume maps were obtained during this period.

Both units were down for an extended period for refueling and repairs and did not return to 75K of rated power until July 23, 1979.

Ten thermal plumes were mapped during the next five consecutive days to complete the monitoring effort.

2.2 Summar of Honitorin Results Reference 2 contains the thermal plume maps, a tabulation of the ambient lake

data, and a

summary of the findings of the thermal plume monitoring with two unit operation.

The following summary. of the monitoring effort is extracted from that document.

Even though all four seasons were not sampled during the plume mapping periods (due to adverse weather conditions and unit outages), it is believed that a

representative collection of varying lake current velocities and directions and of varying ambient lake temperatures were observed.

Because of the per-sistence of lake ice, along with the lake and weather conditions that normally exist during the winter months on the eastern side of Lake Michigan, it is unlikely that sinking plumes, if they are in existence during this time of

year, can ever be monitored.

1

2.2. 1

. Plume Areas, Widths

.and Volumes The thermal plume areas,

widths, and outerlines were determined at a 'depth of one meter.

The Michigan Mater Resources Commission concurred in utilizing the

. one meter data because it eliminated many anomalous results produced by solar heating of the surface water.

Twenty-nine plumes were

mapped,

'and these data are shown in Table 1.

The areas within the 63oF isotherm at a depth of 1 meter varied from 21 acres to 740 acres.

The average area for all 29 plumes was'90 acres.

Three

plumes, exhibited areas greater than the 570 acres specified in the NPDES permits.

i The largest

plume, 740 acres measured on September 8,

1978, was obviously transitory in nature.

It was 35% larger than a plume measured only 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> earlier.

The increase in the size of this plume, as discussed in reference 2,

can be attributed to a change in the ambient temperature during the monitoring period.

A comparison of the ambient temperature measured during the ambient run with the in-situ temperatures shows that during the mapping run the natural lake temperature increased about 2

F above the ambient temperature value used in reducing the data.

The other two plumes exceeding the HPDES specification had areas of 655 and 634 acres and were measured on November 3,

1978.

These plumes were also transitory in nature and can be attributed to variable current directions and low current speeds.

There was also evidence that the recirculation of discharge water was greater than during the previous day (probably because of the low current speeds),

'and this was a contributing factor to the large area.

I The maximum width of the plumes within the h3 F isotherm at the 1 meter depth ranged from 984 to 6,724

feet, and the average width for all 29 plumes was 2,765 feet.

The average plume width for each of the three monitoring 'periods is shown in Table 1.

In general, the width of the plume increased as the area increased;

however, the width for any given plume area varied by a factor of two.

Table 1

Summary of Plume Areas, >lidths, and Volumes Au ust-Se tember 1978 Date Area (acres)

Midth (feet)

Volume (acre-ft) 8/23 8/25 8/25 24 193 311 984 2394 2362 413 2327 2771 9/5 9/5 237 80 2230 1148 1720 1342 9/6 9/6 9/7 287 117 336 2165 1673 4100 1732 1537 1996 9/8 9/8 568 549 740 4838 5642 4264 4029 3678 4852 Average area Average width Average volume 313 acres 2890 feet 2400+ acre-ft Date Area (acres)

)tidth (feet)

Volume (acre-ft) ilovember-December 1978 ll/1 11/1 ll/2.

11/2 ll/3 ll/3 11/7 11/7 154 389 142 200 655 634'94 515 1771 2854 2394 1705 3838 4648 2066 6724 2414 3747 1105 1520 5197 5615 2883 4103 Average area 373 acres Average width

3250 feet Average volume 3323+ acre-ft

~Jul 1979 Date Area (acres)

Midth (feet)

Volume (acre-ft) 7/24 7/24 7/25 7/25 7/26 297 450 109 161 149 2034 3182 2296 3116 1804 2363 3295 951 1551 1190 Average area Average width Average volume 7/26 7/27 7/27 7/28 7/28 269 30 21 171 342 2821 918 886 2624 2755 1625 540 173 1494 2412 200 acres

,2244 feet 1559+ acre-ft

The volumes of'ater within the h3'F.isotherm regions are also summarized in Table 1 for the three monitoring periods.

The volumes of water ranged from 173 acre-feet to more than 5,615 acre-feet.

The average volume for all 29 plumes was 2,300+ acre-feet.f 2.2.2 Plume Thickness Of the 29 plumes monitored, approximately 70K showed no b3 F water at depths below 3 meters.

The remaining 30~~~ showed relatively small areas of b3 F water at the 4 meter depth, with most of these deeper plumes occurring during the November monitoring period..

The

plumes, in general, were relatively thin, most of the warm water being in the upper one meter of the lake.

The majority of the plumes exhibited areas at-the one meter depth that were less than half the surface area.

In addition, the areas at the t>>o meter depth were usually smaller by a factor of two or more than w re the areas at the one meter depth.

2.2.3 Centerline Tem erature Deca Temperature decay along the centerline of the plumes was analyzed by plotting the difference between the plume temperature and the ambient temperature, at a depth of one

meter, versus the center line distance from the discharge structures.

These data are shown on Figures 1, 2, and 3, which correspond to the separate monitoring periods.

1 Comparison of the data 'in Figures 1 and 3 shows similar trends for the summer periods (August -

September,

1978, and July, 1979).

The higher excess tem-peratures decayed'quite rapidly until they became 4 to 5 F above the ambient.

At that point the temperature decay rate became much more gradual.

It can be seen from these figures that the h3 F isotherm may terminate anywhere from 1,310 feet to 11,810 feet from the discharge.

1

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+ implies that the surface areas and volumes were actually larger than the stated value by an amount associated with the surface area that was out-side of the monitoring pattern.

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Excess Temperature vs. Oistance(hugest September, 1978)

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The initial rapid decay rate during these two periods can be attributed to the relatively high discharge velocities that entrained the adjacent lake water.

Because of -stratification, the entrained water temperature was normally lower than the ambient temperature at one meter.

The resulting mixing caused the rapid cooling.

As higher velocities and resulting turbulence dissipated, the discharge waters began to stratify, and the rate of temperature decay became more a function of the ambient lake turbulence and the atmospheric heat dis-sipation.

The gravitational forces associated= with buoyant warm water tend to inhibit vertical mixing with cooler, less buoyant ambient water.

The amount of am-bient lake turbulence, which is a result of energy imparted to the lake by the

sun, wind forces, and Coriolis forces associated with the earth's

rotation, determines just how fast this warmer water will mix with the cooler water.

The turbulence is a major factor in determining the horizontal rate of mixing and spreading of the plume.

And when the turbulence level is sufficient to overcome the buoyant forces, it promotes vertical mixing with the cooler water below.

The warm water on the surface also gives up some of its thermal energy to the atmosphere by convective, evaporative, and radiant heat transfer.

The data shown in Figure 2 represent that obtained during the November 1978 monitoring period.

In this case, it may be seen that the higher temperatures decayed over a

greater distance than during the earlier seasons.

This is attributable to the lake having been we'l mixed; i.e., it had a more uniform temperature vertically than during the earlier seasons.

During this time of

year, when there are no stratification efforts, the water leaving the dis-charge structure is mixed with water having essentially the same temperatu, e

as the ambient temperature at the one meter level.

During earlier

seasons, however, the stratification process allows water that is colder than the ambient temperature at the one meter level to be mixed with the discharge water, thereby cooling it more rapidly.

I!hen compared with the data obtained from Unit 1 operation alone~,

the maximum excess temperatures observed at the one meter level were 3-44F higher during the two unit operation.

The pattern of higher temperatures being observed at a

given distance from the discharge during the fall and winter months, when the lake was well mixed, was also observed in the data from Unit 1'operation~.

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2.2.4 Seasonal Var iations The data for the 29 plumes indicate that the average

areas, widths, and volumes did show some seasonal variation.

This.was true even through there was considerable variation in plumes from day to day, and even during the same day, for any given monitoring period.

It may be seen from Table 1 that the parameters listed increase from the early summer period to the late summer per'iod to the fall period.

A similar effect was observed in the Unit 1

monitoring effort~.

It is believed this effect can be attributed to'he seasonal differences in the stratification characteri stics of the lake.

>lith stratified conditions

existing, the temperature of water entering the circulating water intake structures is normally lower than the ambient water temperature at the one meter level.

This results in the condenser discharge water being cooler, with respect to the one meter depth ambient temperature, than it is in the unstratified condition.

The plume size is therefore smaller than in the unstratified situation.

This effect was fairly evident during the Unit 1 studies4.

The plume sizes during the monitoring of the two units were occasionally influenced by the apparent recirculation of discharge

water, which was seldom observed during the Unit 1 operation alone.

The recirculation of warmer water into the intakes raised the condenser discharge temperatu. es, relative to the one meter ambi ent temperatures, and created larger plumes than when there was no recirculation.

It is felt that the combination of stratification effects with variable and transitory recirculation was responsible for the wide range in plume s"'.zes observed in any given period.

It must be noted that the data collected duri ng this monitoring effort were obtained on relatively calm days, days during which the wind and waves were not severe enough to prevent use of the boat and monitoring equipment.

During days when lake conditions were severe, the sizes of the thermal plumes would be expected to be smaller, on the average, than those reported in this study.

This is because the increased turbulence in the lake, produced by the inten-sified wave action, would promote mixing and dissipate the plume more rapidly.

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2.2.5 Areas of Influence The plume maps obtained during this monitoring effort were utilized to define the region of the lake, at the one meter depth, that was occupied at one time or another by water with a temperature more than 3

F.above the ambient water temperature.

This region is shown in Figure 4.

Areas have been shaded to portray the percentage of plume maps having specific locations influenced by the h3'F'ater when Units 1 and 2 were both operating at 75% full power or

.more.

The skewing of the shaded areas to the north of the plant is the result of the predominantly north-flowing currents observed 'during the monitoring periods.

2.3 Ambient Conditions The ambi ent 1 ake temper atur es and currents were observed to be extremely variable and apparently had significant effects on the thermal plume behavior.

Ambient lake stratification had a definite impact on the plume size.

2.3. 1 Ambient Lake Tem erature Lake temperatures were measured in the vicinity of the D.

C.

Cook Nuclear Plant by means of vertical arrays of thermistors and in-situ temperature recorders anchored on the lake bottom.

Three temperature recorders were utilized--one

north, one

south, and one west of the discharge area.

An example of the. lake temperature data is shown graphically in Figures 5 and G.

This representation illustrates the extreme variability of the natural lake temperatures as a

function of depth.

The plots show the daily

maximum, minimum, and average temperatures, and the dashed lines show plus and minus one standard deviation.

These variations, measured in the vicinty of 'the Donald C.

Cook Nuclear Plant.,

showed magnitudes of temperature changes that exceeded temperatures associated with the Cook Plant's thermal discharges.

For instance, changes of more than 20'f were seen occurring from one day to the next over the region of the lake monitored by the recorders.

This re-presented a rate of change of the energy content of the water in this same region that far exceeded anything that the Donald C.

Cook Nuclear Plant could produce.

Individual temperature sensors regularly recorded daily temperature variations of more 'than 10'F.

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Cook Units 1

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These:natural temperature variations and the spatial and temporal variations in lake currents make it impossible to predict what a plume might do from one day to the next.

These natural variations,

however, are evidence of the dynamic natural processes that exist in the lake and that can be, expected to disperse and dissipate the Cook Plant thermal discharges.

A reality of thermal plume monitoring on a large lake like Lake Nichigan is the virtual impossibility of defining a

single ambient temperature.

As graphically illustrated by the in-situ data (Figures 5

and 6),

the natural temperatures vary both spatially and temporally in the area near the power plant.

The ambient temperatures used in reducing the data from this study were defined as the average of all temperature readings obtained during the "ambient run."

(The "ambient run" consisted of measuring the water tem-peratures at various depths during.

a shore-perpendicular transect in the region up-current from the discharge area.)

A review of the data in refer-ence 2

shows that at times this involved averaging data with a spread of more than 2'F.

This spr ead in the ambient temperature data represented primarily spatial variations and did not reflect the temporal variations.

The ambient temperature utilized in reducing of the data can have a signifi-cant effect on the size of the area within the h3'F isotherm, as a review of the data related to the 740 acre thermal plume measured on September 8, 1978, shows.

For example, if the ambient temperature were actually 1'F higher than that utilized for reducing the data, the plume area would be reduced from 740 acres to 113 acres.

For this particular plume, the data averaged to evaluate the ambient temperature showed a

spread of l~F.

In addition, the in-situ temperature recorder on the up-current side of the plume indicated an ambient temperature approximately 1'F higher than that determined by averaging the "ambient run" temperatures.

A 0.5'F change in the ambient temperature used to reduce the data would have changed the plume area several hundred acres.

Temporal and spatial variations of the ambient temperature in the near shore waters of Lake Michigan often result from upwellings, from vertical motion of the thermocline produced by internal

waves, and from solar heat'ing.

Upwel-lings are produced in a stratified lake when a strong, persistent wind drives 17

the warm surf'ace water to the downwind side of the lake and "tilts" the thermo-cline sufficiently to cause the colder water below the thermocline to come to the surface on the upwind sid of the lake.

This results in measured ambient temperatures that increase with distance offshore.

Internal waves (vertical motions of the thermocline produced by gravitational and Coriolis forces) create temperature fluctuations as a function of time at any given measurement location as the thermocline moves above and below the sensing instrument.

Solar heating results when solar energy is absorbed by the water mass.

Host of the energy is absorbed near the

surface, causing the temperature to in-crease in a relatively thin layer.

The remainder of the energy is absorbed in the water column to the depth of penetration, which is a function of the purity of the water.

Since the. solar energy input is uniform over the surface of the lake, the shallow,

inshore, and often more turbid water receives more energy per unit volume and is thereby warmed more rapidly than is the offshore water.

In this

case, the measured ambient temperature would decrease with.

distance offshore.

Solar heating also results in variations of the tem-perature with time.

Temperature increases of 5

F within a

two hour period have been observed in the top one foot of water on a hot, calm summer day.

Mater warmed by solar heating cannot be differentiated from water heated by the power plant.

Thus, when there is significant solar heating of the sur-face, it becomes very difficult to (3.) define an ambient surface temperature because of large temperature variations, and (2) to define the boundaries of the thermal plume at the surface.

These natural phenomena, which result in ambient temperature variations, cannot be modeled in a hydraulic modeling facility.

The hydraulic modeling is done with water at a uniform temperature.

2.3.2 Ambient Lake Currents The single most important physical parameter affecting the position and trajec-tory of the thermal discharge is the ambient lake current in the vicinity of the discharge.

The current also affects the size of the discharge plume, but this effect was masked by size variations induced by stratification and re-circulation.

Four current meters were used for this study of ambient lake currents--two near shore and two offshore.

18

The graphical representations of current speed and direction (Figures 7 and 8) were used to compare current speed and direction for the various meters.

Usually, the current speed plots exhibit the same general trends for all four meters.

Even better correlation exists between the current speed trends for the two inshore meters and for the two offshore meters.

While the overall trends

agree, significant.differences in current speeds often occurred at any given time.

In other

words, long-term trends in current speed show some consistency at the four moni,toring locations, but short-term local current speeds show considerable variation.

The plots of current direction show very poor correlation from one current meter to another.

For instance, for the period November 17-19, 1977 (Julian dates 321 to 323),

the northern offshore meter indicated north-northeast flowing currents; the northern inshore meter showed currents flowing to the southwest; the southern offshore meter recorded current directions varying from the northwest to the north-northeast; and the southern inshore meter indicated northwest flowing currents that occasionally shifted to the north-east.

For the period November 29,

1977, to December 19,

1977, the northern inshore and offshore current meters recorded current directions that differed by 105 degrees or more over 50

% of'he time.

Not shown on these plots is the correlation between the surface currents, as measured by drogues, and the currents measured by these meters at depths of 11 and 22 feet.

As discussed in the descriptions of the various plumes~, there were many instances when the surface currents and bottom currents were flowing in different directions.

The two drogues also exhibited differences in the near shore and offshore surface current direction, once showing the two sur-face currents flowing in opposite directions.

These variations and differences in the currents, both temporal and spatial, serve to highlight the complex and unpredictable flow regimes that exist in the near shore waters of Lake Michigan.

Attempts to 'obtain meaningful correla-tions with the meteorological data were unsuccessful, since there was often no correlation between the various current measuring devices.

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The plots of current direction, similar to that shown in Figures 7 and 8, were used to determine current directional persistence data for the three years

-that the currents were measured.

An example of these data (see. Figure 9) shows the percentage of time (based, upon recorded -data) the lake currents flow in a given direction for a given number of days.

Figure 9 also shows that the directional persistence of less than one day occurred under 28% of.,the time for all but the northern inshore

location, where it occurred 55% of the time.

Persistence of more than two days occurred 77% of the time at the north offshore locations, 53% of the time at the south offshore

location, and 21 and 47% of the time at the northern and southern inshore locations, respectively.

The north flowing currents were only slightly more persistent than the south flowing currents at the southern locations, and the probability of north or south flowing currents was about equal at the northern locations.

The data for 1979 generally showed more persistence than.did the data from the previous two years.

The surface currents during this monitoring effort indicated north flowing currents for 67% of the measurements, south flowing currents for 29% of the measurements, and east flowing currents for 5% of the measurements.

This sample of surface currents was probably biased by winds from the northwest through the northeast, because these

winds, which produced south flowing surface

currents, also produced larger waves that might well have prevented the boat from going to the plant, to make the measurements.

The temporal and spatial variations in lake currents measured near the D.

C.

Cook site are the result of complex eddying motions, covering a wide "spectrum of eddies."

Such motions are associated with the turbulent flow conditions that almost always exist in large lakes.

The state-of-the-art of mathematical modeling is not adequate to allow prediction of the micro-effect of eddies at a given location.

Similarly, hydraulic models, although designed to produce turbulent flow in the simulated lake water, cannot adequately model the spec-trum of eddies observed in the lake.

22

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.Figure 9.. Current Directional. Persistence (1979) 23

2.3.3 Strati fication The effect of stratification, as indicated in Section 2.2.-4, appears to be the primary factor influencing the plume size.

Since stratification is seasonal, this produces the seasonal variations observed during both'onitoring efforts (Reference 2 and 4).

The lake begins to stratify in spring as the rate of solar heating begins to increase.

During this time, the -layer of warm water on the surface is rela-tively thin, and thus the condenser cooling water, which is discharged near the lake

bottom, can entrain more cold water before it reaches the surface than when the thermocline is at greater depths.

This results in the smaller plumes that are observed during the spring.

"Negative plumes" (plumes in which the water is cooler than the ambient water) were observed during the first monitoring effort~.

As the solar energy input. to the lake increases during late spring and

summer, the stratified layer of warm water becomes thicker.

Under these conditions, the intake water. temperature is still considerably cooler than the ambient temperature at.the one meter depth.

However, the condenser cooling water is now entraining and mixing with more of the warm water in the stratified layer, thereby increasing the size of the area within the h3'F isotherm.

Mhen the-stratified layer in the lake is deep enough to surround the intake structures, the temperature of the water entering the condensers is consequently

warmer, and the differential temperature between the condenser discharg water and the ambient temperature is greater.

This condition occurs during the fall and produces the largest plumes.

These conditions, i.e.,

relatively uniform temperatures between the intakes and

surface, are the conditions that were simulated in the hydraulic modeling of this discharge.

24

. 3.0 SUblhiARY OF b)ODELING EFFORT The once-through circulating water system for the D.

C.

Cook Plant utilizes an

offshore, submerged, horizontal jet-type discharge structure for each of the two units.

The th rmal plume which evolves from these discharge structures may be characterized by three flow regimes.

The "near-field" region of the thermal plume is that region where the plume is well defined and the velocity of the water in the plume is still significantly greater than the ambient water body velocity.

This velocity difference be-tween the plume and ambient water body produces considerable turbulence and entrainment that results in lateral and vertical spreading of the plume.

This induced mixing is enhanced to a lesser degree by the ambient water body tur-bulence.

A "transition region" occurs when the ambient turbulence approaches or exceeds the jet-induced entrainment as an important mechanism in the dilu-tion process.

Ultimately, at a sufficient distance from tho discharge, i.e.,

the "far-field," the excess jet velocity is dissipated, and the plume is advected in the direction of the ambient current.

Dilution in the far-field is controlled by ambient turbulent dispersion.

3.1 H draulic Model Estimates of the excess temperature distribution'within the near-field and the transition region between the near-and far-field were obtained from a hy-draul ic model study performed by Alden Research Labor atori es of

Holden, t)assachusetts.

A large and elaborately detailed hydraulic model was us d to simulate the near-field, jet-induced entrainment.

This enabled an accurate simulation of the interaction of the discharge plumes from the two multi-jet structures with each other and with the lake boundaries.

The hydraulic model was designed on a scale ratio of 1:75 for both the vertical and horizontal dimensions.

The model utilized prototypal effluent and ambient water tem-peratures and simulated the dynamics of the interaction between the discharge jets and the ambient lake current.

The model basin was approximately 100 by 47

feet, thus representing a portion of Lake fhichigan measuring 7500 feet along the shoreline and 3500 feet out into the lake.

Lake bottom contours were reproduced in the model with templates having profiles at any section geometrically similar to those at the corresponding section in the lake.

25

The model had two water flow systems.

one for simulating lake flow and the other for.simulating power plant flows.

For lake flow, water was pumped from a

sump through a flow distributor onto one end of the model basin and allowed

,to flow out at the other.

Flow rate to the model was measured by a venturi meter in the supply line to the flow distributor and was controlled by a valve downstream of the venturi meter.

Mater level in the model basin was con-trolled by weirs at the downstream end-of the basin.

The'emperature of the water flowing into the basin from the flow distributor was governed by the temperature of the water in the sump.

The latter temperature was adjusted by mixing hot and cold water.

The power plant once-through condenser cooling water system was simulated by a system consisting of intake piping and structures, discharge

piping, and a

mixing tank.

The intake and discharge piping for each unit was fitted with orifice meters and valves for measuring and regulating the flow into and'out of the mixing tank.

Simulation of power plant operation consisted of setting the discharge flow on each unit equal to the intake flow on each unit and mixing the intake flow with the amount of hot water needed for a given temperature rise.

A portion of the mixture equal to the amount of hot water added was allowed to flow to waste.

Temperature measurement and recording in the model was by a network of thermo-couples connected to a data logging system.

There were 137 thermocouples in the network, plus two thermocouples in each of the intake and discharge struc-tures and'hree thermocouples immediately downstream of the flow distributor.

These thermocouples were for measuring the temperature of.the ambient water upstream of the power plant, and there were additional thermocouples for measuring air wet and dry bulb temperatures and pump temperatures.

3.2 Hathematical Hodels The excess temperature distributions for the far-field were obtained by the use of the hydraulic model data and analytical models.

The results of the hydraulic model study were used to initialize a far-field analytical model to 26

I

obtain the excess temperature distribution in tho far-field for both stagnant f

and representative lake current conditions.

In the stagnant lake case, the extrapolation of the near-field excess tempera-tures to the far-field entailed the use of an empirical correlation by Meigels for plume centerline temperature decay.

By trial and error, an imaginary discharge was defined that would yield a match with the temperatures obtained from the hydraulic model results.

Once a match was established, the cor rela-tion was used to estimate the centerline location of the excess temperature isotherms in the far-field.

The widths o'" the far-field excess temperature isotherms were approximated by increasing the plume width linearly as a func-tion of center line distance from the discharge, as proposed by Stolzenbach and Harleman.6 The appropriate linear growth rate was determined from the hydr au-lic model data.

For modeling situations involving a lake current, an overall centerline tra-jectory was obtained by averaging the trajectories of Onits 1

and 2.

The complexity of the dischargo jet configuration made this necessary.

The center-line trajectories determined by this process compared favorably with the hydraulic model data.

A second step involved the derivation of a model that would simulate the decay of excess temperature in the far-field under tho condition of an ambient cu> rent.

The analysis used the Sundaram model, which assumed the plume in the far-field to be moving along with the same velocity as the ambient lake current.

The width of the thermal plume was estimated by assuming the far-field excess temperature to be distributed normally about the plume centerline.

The mathematical far-field model was then coupled to the near-field and transition

regions, as modeled in the hydraulic tests, by assuming that the far end of the last closed excess temperature isotherm was an imaginary outfall whose location dimensions, temperature, and flow were obtained directly fr om the hydraulic model data.

The results of this analytic technique were fully reported in references 8 and 9 and are summarized below.

It was noted that because the ambient lake tur-bulence and heat transfer to the atmosphere were not adequately represented by the mathematical

models, the results of these analytic extrapolations of the hydraulic model data would conservatively overestimate the size of the plume within the D3 F isotherm in the far-field region.

27

3.3 Ho'del in'esul ts Hydraulic model plume data were generated for two units operating at full power, for one unit operating at full power, and for one unit operating at 81/o of full power.

The effects of a

range of ambient lake currents were studied in each case.

A comparison of the data for ono unit operation with the field measurements was reported in the 316(a)

Demonstration Report submitted to the ViMRC in January, 1977.

Figures 10-l3 illustrate the results of the combined hydraulic and mathemat-ical modeling predictions of the plume behavior with both Units 1 and 2 oper-ating at full power.

The figures represent the effect of ambient lake current speeds of 0, 0.2, 0.5, and 1.0 fps, respectively.

The results from these studies are tabulated in Table 2

and show that the maximum plume area of '570 acres was observed at a lake current speed of 0.2 fps.

It is postulated that this effect is the result of the interference the two discharge structures exert upon each other due to the warm water dis-charged from the upstream structure being entrained by the plume discharged from the downstream structure.

At higher lake current

speeds, the ambient lake momentum would suppress the effect of this entrainment by increasing the amount of cooler lake water available for dilution of the plume.

The zero-current lake condition resulted in some re-entrainment of warmer water but, to a lesser extent than in the 0.2 fps current speed test, thereby producing a

smaller plume area as compared with the 0.2 fps case.

Table 3 summarizes the predictions of the plume temperature and velocity as a

function of plume centerline distance from the discharges.

The predicted plume areas,

depths, and volume for a lake current speed of 0.2 fps are shown in Table 4.

An estimteo of the dimensions of the lake region that-would, at one time or another during the plume's meandering, contain plume water with an excess temperature of 3'F or more is summarized in Table 5.

28

Table 2

Predicted Plume Areas vs.

Lake Current Speeds Current Speed (f s)

Area Mithin Given Isotherms (acres) 0.2 z5'F SO'F 15 135 110 225 a3'F 530 570 0.5 95 220 85 460 190 Table 3

Predicted Plume Temperature and Velocity vs.

Distance CL Distance (ft) 0 125 400 650 1275 3000 4410 6600 12350 Excess Temperature

(~

F

19. 5

10. 0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 Veloci ty

~(f s)

13. 0 6.2 2.4 2.2 1.6 1.0

0. 65 0.2 0.2 29

Tail e 4 Predicted Plume Areas,

Depths, and Volumes Excess Temperature Isotherms

('F) 10 and 7

7 and 5

5 and 4

4 and 3

TOTALS Area Between Excess Temperature Isotherms (acres) 6.6 128. 0 148. 0 289. 0 571.6 Plume Depth

~(summer)

(feet)

11. 0

14. 0

12. 0 10.5 Plume Depth (winter)

(feet)

16. 5

28. 5

30. 0 27.5 Volume (avg.

summer and winter)

(cubic feet) 3.9 x 106" 5.32 x 107 6.62 x 107 1.41 x 10s 2.64 x 10s Table 5

Predicted tlaximum Extent of Plume (derived from a variety of current conditions)

Excess Temperature oF)

Distance from Discharg Structures (ft) 3 North 8 South 9400 6200 2100 500 East 1200 1200 1200 00 Mest 7400 5200 2600 600 30

4.0 COMPARISON OF FIELD DATA MITH PREDICTIONS Comparison of field data with one unit operation, as reported in reference 10, indicated that the modeling technique described in Section 3.0 was conserva-tive in predicting the plume size and shape.

Twenty-eight of the thirty plumes measured had areas considerably smaller than the predicted area.

The two plumes with areas larger than that predicted by the models appeared to be influenced by transien conditions in the lake, plant operating difficulties (higher condenser hT's because of two pump operation),

and some possible recirculation effects.

4.1 Plume Areas Similar results were observed during the monitoring of two unit operation in that 26 of the 29 plumes measured had areas smaller than the 570 acres pre-dicted by the models.

As discussed in Section

2. 1 and in reference 2, the

'three plumes larger than the predicted maximum were transitory in nature.

That is, they appeared to result from changes, in the ambient lake temperature during the monitoring period and from transient and variable lake currents that probably created some recirculation of discharge water.

The average area for all 29 plumes was 290 acres, approximately one-half of that predicted by the models.

A review of Table 1 will show that the average area of the plumes measured during July (1979) was 200 acres.

The average area for plumes measured in August-September (1978) was 313 acres, and the average area was 372 acres for the plumes measured 'in November-December (1978).

This trend, i.e., the plume area increasing as the year progressed, was also observed during the mon-itoring of one unit.

As discussed in Section

2. 4, this effect is believed to result from seasonal changes in the stratification characteristics of the lake:

As the thermocline goes

deeper, the plumes become larger.

The limit to this effect would be when the

lake, or the area of the lake affecting the thermal discharge, achieves a

uniform temperature.

A review of the ambient temperature data in reference 2

shows that this condition existed during the November-December monitoring period.

'31,

The hydraulic scale model used to predict the thermal plumes utilized uniform temperature water to s,imulate the ambient lake.

It could be expected, there-fore, that the modeling represented the worst-case situation.

Since the real lake does not achieve a uniform temperature until late fall, it may be con-cluded that data taken then would provide the most realistic comparison with the models.

i It may be seen from Table 2 that there is an apparent effect of the current speed on the plume size.

However, close examination of the data li.sted on Figures 10-13 suggest another potential explanation of the variation in plume area.

It may be seen that for current speeds of 0 and 0.2 fps the intake temperatures are 1.5 to F higher than the ambient temperature, probably because of recirculation.

Thus, the larger plumes observed in the models at the lower current speeds may have been more the result of the recirculation effect than of the current speed effect.

If this were the case, the modeling results could be said to have produced a

more realistic simulation of the actual conditions than one would conclude by assuming that the current speed effect was the major parameter.

4.2 Center line Temperature Deca Rate Table 3

shows the predicted centerline distances from the discharge of the vari ous excess temper atur e isotherms.

These data are pl otted on Fi gures 14, 15, and 16 to show the comparison between the field data and the predictions.

It may be seen on -Figure 14 that the model predictions tend to over estimate the distances that the various isotherms would exist from the discharge.

In other

words, the plume temperatures tend to decay more rapidly during this period than predicted by the models.

Figure 15 shows that the model predic-tions similarly predict greater centerline distances for the isotherms than were observed by the field measurements, though not to the same degree as those measured earlier in the year.

It is interesting to note that the large 740 acre

plume, measured on September 8,

1978, (designated by the arrowhead) exhibited a

temperature decay rate that was greater than the predictions, except at the h3 F

isotherm.

In other

words, the area between the h3 and 64 F

isotherms was inordinately large compared to the rest of the plume.

Figure 16 shows

that, the centerline temperature profile for the November period was predicted fairly well by the models.

The higher excess temper-32

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3 Shoreline Donald C.

Cook Nuclear Plant Units 1

8 2

Isotherm Depth - Surface Lake Current 0.0 fps TEf'1PERATURES oF Intake South - 69.0 Hiddle - 69.3 North - 68.4 Disch~ar e hT aT Ambient Water Unit 1 - 21.6..

67.6 Unit 2 - 17.2 Ambient Air Wet Bulb - 68.1 Dry Bulb - 71.2 Hydraulic Test Data (9/2/72, 9/22/72, 10/2/72, 10/11/72)

Figure 10

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Figure 11

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Cook Nuclear Plant Units 1 5 2

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Figure 13

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~ G-25-78A X 8-26-78B 9 78A C3 9-5-78B 0

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Excess Temperature vs. Oistance(August

- September, 1978)

4

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QJ 8

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rj 1l-Q l1-0 1l-0 11-PREDICTIONS 0

1 I 1-78 A 1 7GB 2-78 A 2-78B 3-78A 3-78 B 7-78A 7-78B 00

~ --

~P 0

0 0

0 1000 2000 3000 4000 Distance from Discharge, f1eters Figure 16.

Excess Temperature vs.

Distance(ilovember, 1970)

atures persisted

-somewhat farther than the model predicted,, while the lower excess temperatures did not persist quite as far as the model predicted.

This is particularly true if the two 600+ acre plumes believed to be transitory in

nature, measured on November 3, are discounted.

Again, in view of the fact that the lake conditions existing during the plume monitoring in November 1978 most closely approximated the hydraulic.model conditions, it may be concluded that the modeling results were confirmed quite well by these data.

4.3 Plume De ths The modeling results shown in Table 4 indicate a predicted plume depth ranging from 10~> to 14 feet in depth during the summer months and 16~> to 30 feet deep during the winter.

Approximately 70Fo'of the field data showed little or no h3'F water below the 10 foot depth.

tlost of the plumes exhibiting the D3'F water at the 13 foot depth were measured during the November monitoring period.

Since the November conditions most'losely approximated the con-ditions in the hydraulic model, it may be concluded that the model did a good job in predicting the plume depth.

Earlier in the year,

however, the field data indicated plumes that were not quite as deep as predicted by the model.

No data were obtained to allow comparison with the predicted winter plume thickness.

Plume Volume Table 4

shows that the models predicted an average volume of 2.64 x 10 cubic feet (or 6,060 acre-ft) for the plume.

This volume was calculated assuming a

plume depth of 10 feet and also assuming a constant plume area at all depths.

The average volume of the plumes measured in the field during November was 3323+ acre-ft, little over half of the predicted volume.

The discrepancy between the prediction and the field data could be explained by the fact that the predictions assumed a

constant plume area as a function of depth.

The field data indicated that the area decreased with depth, and an allowance for this factor would have reduced the predicted volume.

40

4.5 Region of Influence The modeling and analytical results were used to estimate an area of influence of the thermal discharge.

The data, tabulated in Table 5 were used to calcu-late an oval-shaped envel'ope representing the area of the lake that would be influenced at one time or another by the h3 F water during the plume's meandering and fluctuation.

An approximate oval of these dimensions was superimposed on Figure 2 to compare it with the region of influence observed during the field studies.

This is shown in Figure 17 for the one meter depth.

The measured area of influence extended further offshore and to the north than predicted by the modeling.

This result was also observed in the monitoring of the one unit operation.

41

Percentage of Honitorin~

Time That One Heter a3F~

Area was Located in 2ones Indicated 3~ - 25>>

25">> - 50K 50" - 75$

75>> - 100>>

0 200 400 Shoreline.

0 0

Region of Lake Influence by 0.

C.

Cook Units I f 2 Discharge (Power Levels Greater than 75%)

Figure 17

5. 0 SUt iNARY Data from the in-situ temperature and current recorders showed a large vari-ability in the natural temperatures and currents in the lake. near the Donald C.

Cook site.

The natural temperature changes represent a rate of change in the energy content of the water that far exceeds anything the Donald C.

Cook Nuclear Plant-could produce.

The variability in the currents are the result of complex eddying motions that, along with the natural temperature varia-

tions, are practically impossible to simulate in a hydraulic model.

A comparison of'he predictions of plume size and location with the data obtained during the monitoring program showed that, with the exception of the three transitory

plumes, the models predicted areas larger than were observed in the field.

The prediction of the excess temperature profile along the plume centerline showed relatively good agreement for the plumes measured in November (when the lake temperature was relatively uniform).

However, the models over-predicted the excess temperature as a function of distance from the discharge during the earlier monitoring periods.

The prediction, of the plume depth agreed well with the

data, but the predicted volume was almost twice as great as the observed volume.

Although the observed.volume was smaller than the prediction, the observed region of influence of the h3'F water was somewhat larger than the predictions.

Conditions in the lake during the late fall monitoring periods most closely approximated the uniform temperature conditions utilized in modeling the ther-mal plume.

The conditions during late fall also produced the largest plume areas because the intake water temperature is essentially the same as the ambient water temperature used to define the excess temperature isotherms.

(Strat.'fication effects that occur earlier in the year cause the intake water to be cooler than the ambient water temperature.

This results in a smaller temperature difference between the discharge water and the ambient tempera ure and therefore produces a smaller plume.)

This same condition of relatively uniform lake temperatures persists during the winter and until the spring warming--and the beginning of stratification--starts in late l1arch or early April.

Therefore, it is felt that this monitoring effort, even though it, was unable to monitor plumes during the February-triarch period and during the 43

April-tray period, has provided adequate data for validating the modeling techniques utilized for the D.

C.

Cook plant.

And it has provided plume data during the time when the plume would be expected to be the largest.

It is highly unlikely that measurements of the thermal discharge during the winter months -can be made at the Donald C.

Cook plant.

The adverse weather and lake conditions existing during the winter, the accumulation of ice, the unavailability of boats during that time of year, along with general safety considerations, render it virtually impossible to obtain winter plume data.

Plume measurements during the spring season will also be almost impossible to

obtain, since planned maintenance schedules will have one or both of the units down during this period.

It is further felt that data obtained during this time of year are of little significance with respect to comparison with the modeling data because of the stratification effects.

As the smallest plumes occur during this time of year, the data are also of little significance with respect to validating the allowable area specified in the NPDES permit.

REFERENCES U.S.

Atomic Energy Commission, Directorate of Licensing, Appendix B,

"Environmental Technical S ecifications for Donald C.

Cook Nuclear Plant, Units. 1 and 2 Berrien Count Mich> an Docket No s.

50-315 and 50-316,"

October 25, 1974 -

Amended November 8,

1978, by Nuclear Regulatory Com-

mission, "Amendment Ho.

26 (Unit 1)/Amendment No.

8 (Unit 2)."

Indiana 8 Michigan Power

Company, Donald C.

Cook Nuclear Plant, Units 1

8; 2, "Report on the Characteristics of the Thermal Discharge-from Donald C.

Cook Units 1

8: 2, Volumes 1

and 2," submitted to Chief, Mater equality Division, Michigan Mater Resources Commission, January 1980.

Chief

Engineer, Michigan Mater Resources Commission, "Michigan Mater Resources Commission Authorization to Discharge Under the National Pol-lution Discharge Elimination System,"

Permit No.

MI, 0005827, December 7,

1974.

Indiana 8 Michigan 'Power

Company, Donald C.

Cook Nuclear Plant, Units 1

and 2,

"Report on the Performance of Thermal Plume Area Measurements, Volumes 1 and 2," submitted to Chief Engineer, Michigan Mater Resources Commission, June 1, 1976.

Miegel, R.

L., I. Mobarek, and Y.

Jen (1964),

"Discharge of Warm Mater Jet Over Sloping Bottom," Technical Report HEL 3-4, Inst. of Engineering

Research, Univ. of California, Berkeley, Calif., Nov.

1964.

Stolzenbach, K., and D.

R.

F.

Harleman (1971),

"An Analytical and Experi-mental Investi gati on of Surf ace Discharges of Heated Water,"

M. I.T.,

Hydrodynamics Laboratory Technical Report No. 135, Feb.

1971.

Sundaram, T.

R.,

C.

C.

Esterbrook, K.

R.

Piech, and G.

Rudinger (1969),

"An Investigation of the Physical Effects of Thermal Discharges into Cayuga Lake (Analytical Studies),"

CAL Ho. VT-2616-0-2, Cornell Aeronau-tical Laboratory, Inc.,

Hov.

1969.

Testimony of J.

J.

Markowsky, Ph.D., before the Atomic Safety and Licen-sing Board in the Matte-of Indiana 6 Michigan Electric Co.

and indiana and Michigan Power Co.

(D.

C.

Cook Nuclear Plant, Units 1 and 2), Docket Hos.

50-315 and 50-316, Feb.

11, 1974.

Indiana K Michigan Power Co.

(1975),

"Plan of Study and Demonstration Concerning Thermal Discharges at the Donald C.

Cook Nuclear Plant," sub-mitted to the Michigan Mater Resou. ces Commission, April 7, 1975) (pp.

E 88-120).

Indiana 8c Michigan Power

Company, Donald C.

Cook Nuclear Plant, Units 1

and 2,

"Report on the Impact of Cooling Mater Use at the Donald C.

Cook Nuclear Plant,"

submitted to Chief Engineer, Michigan (later Resources Commission, January 1,

1977.

'IV 0

APPENDIX

SUMMARY

OF THE MONITORING PERIODS The log of the monitoring effort involved in this study is summarized below.

It recounts some of the difficulties encountered in performing this monitoring effort on Lake Michigan, particularly during the colder months.

Au ust 21 - Se tember 8

1978 Monitoring of the thermal discharges from both Unit 1 and Unit 2, with both units operating at greater than 75% full power, was initiated on August 21, 1978.

Eleven plumes were mapped on six different days.

Aug. 21-Aug. 22 Aug. 23-Aug. 24-Aug. 25-Aug. 26-Installed

.monitoring equipment on the boat.

. Boat generator failed and required repair.

Serviced current meters and temperature recorders.

No monitoring.

Unit 1 at 40%

power, Unit 2

down.

Calibrated intake and discharge thermocouples at the pl ant.

Mapped 1

plume.

Sky clear and sunny.

Lake changed from light chop to glassy.

No monitoring.

Plant was down for the day.

Worked on equipment.

Mapped 2 plumes.

Sky overcast, foggy in the morning; light wind, 1-3 foot swells.

Plume mapping a tempt aborted after Unit 1 tripped early in the run.

Aug. 26-Sept. 4-Sept. 5-Unit 1 down.

Mapped 2

plumes.

Sky clear and

sunny, light wind, lake calm.

Sept. 6-Happed 2

plumes.

Sky partly cloudy then clearing, moderate

breeze, 2-4 foot swells.

Sept. 7-Sept. 8-Mapped 2 plumes.

Sky sunny with haze, light wind, 1-2 foot swells with chop.

Mapped 2

plumes.

Sky sunny and clear, light wind, 2-3 foot swells with chop.

October 30 - December 15, 1978

'onitoring of the thermal discharge'uring the fall season was begun on October 30, 1978.

Eight plumes were mapped on four days early.in November.

Heather conditions or plant operating conditions prevented additional plume mapping until ihe effort was terminated on December 15.

Oct. 30-Oct. 31-Hov. 1-Installed equipment on boat and checked its operation.

Gale warning prevented monitoring attempt.

Serviced

'current meters and temperature recordings.

Aborted monitoring attempt because of high winds and waves and failure of the generator on the way to the plant.

Calibrated intake and discharge water thermo-couples at the plant.

Mapped 2 plumes.

Sky sunny and hazy, light wind, 1-2 foot waves.

Hov. 2-Hov. 3-Nov. 4-Hov. 5 Hov. 7-Mapped 2 plumes.

Sky sunny with haze, 1-3 foot waves with whitecaps.

Mapped 2

plumes.

Sky sunny with some

haze, light wind, 1-2 foot waves.

Ho monitoring.

Unit 2 at 60% power.

Unit 2 at less than 75% power.

Mapped 2 plumes.

Sky had scattered

clouds, no wind, 1 ake flat.

Hov. 8-No monitoring.

blind blowing at 25 -

30

mph, 4 foot waves.

Nov. 9-Nov. 10-Ho monitoring.

Lake too rough--4 foot waves with whitecaps.

No monitoring.

Unit 2 shut dovn for scheduled main-tenance.

Hov. 27-Nov. 28-Hov. 29-Hov. 30-No monitoring.

Boat had engine problems.

Unit 2 at 60% power.

Lake was rough.

Moved equipment to another boat.

No monitoring.

Mind 17 - 25 mph, 4-6 foot waves.

Bad weather.

On standby.

Dec. 1-Monitoring attempt aborted because of high wind and waves.

Dec. 2 Dec. 7-Dec. 8 Bad weather.

On standby.

tlonitoring.attempt aborted after Coast Guard warning of high winds.

Bad weather.

On standby.

Monitoring effort aborted.

t1arch 27 -

A ril 6 The winter season monitoring effort was delayed until triarch 27,

1979, because of heavy lake ice and a frozen St.

Joseph River.

No plume mappings were obtained because of bad weather prior to an extended shutdown of Unit l.

Mar. 27-ttar. 28-tahar. 29-t)ar. 30-Lake and mouth of river blocked by ice.

Large quantities of lake ice.

No monitoring.

Lake ice.

Boat engines being repaired.

honitoring effort aborted because of ice floes at river mouth.

Mar. 31-Apr. 3-Apr. 4-Apr. 5-Apr. 6-On standby, waiting for ice to clear.

monitoring attempt aborted at the plant after data system became erratic because of the cold.

t1onitoring effort aborted on way to plant because of increasing winds and vjaves.

Minds gusting to 80 mph that night, 15 foot waves on lake.

Minds still gusting to 30 knots.

Unit 1 tripped, would be down for refueling until t1ay 30.

Monitoring effort terminated.

Jul 23 " Jul 20 1979 No monitoring was performed during the April 15 -

Nay 15 period because the two units were down for refueling and repairs for an extended period.

Both units were not at 75% povfer until July 23, 1979.

Eleven plumes were subse-quently mapped during six consecutive days.

~ p

July 23-July 24-Napped 1 plume (practice run).

Unit 2 at 60% power.

Napped 2

plumes.

Sky was cloudy.

Lake'had 2 foot

'aves.

July 25-Happed 2

plumes.

Sky was cloudy.

Mind 12-20

mph, 1-2 foot waves.

July 26-Happed 2 plumes.

'Sky sunny and clear, OM wind, 2-5 foot waves.

July 27--

July 28-Napped 2

plumes.

Sky sunny with light haze, light wind, 1-2.,foot waves.

Happed 2

plumes.

Sky cloudy, slight drizzle, light wind, 1-2 foot waves.

Appeared to be strong current to north.

49

i.)