Text

Predicted Thermal Plume Resulting from Operation of Units 1,2 & 3
	ML19319D132
Person / Time
Site:	Crystal River
Issue date:	06/20/1975
From:	; FLORIDA POWER CORP.
To:	;
References
	NUDOCS 8003130702
	Download: ML19319D132 (64)
	v • d • e

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The Predicted Thermal Plume Resulting From The operation of Units 1, 2 & 3 At The Crystal River Power Plants Florida Power Corporation June 1975

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d NRC Docket No. 50-302 I

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i INTRODUCTION-Any natural body of water, such as an estuary, may be described as a :tathematical system composed of interacting subsystems. The system is influenced by a variety of phenomena' such as wind, rainfall,-solar radiation and runoff. In the case of estuaries, the gewetric configuration and geomorphic composition of the basin will also have a significant influence on the system. The response of the system to these influences determines the spatial and t nporal distribution of concentrations of various subste.nces which affect water quality.

For a mathematical description ox' "model" of a system to be viable it must in some way reproduce observable phenomena which are associated with the modeled system. The nature and complexity of the model is determined by the characteristics of the particular phenomena being investigated.

A thermal enrichment model has been developed (Palmer, in preparation) to compare and predict plume configurations of j

thermal effluents discharged into esttarine ewironments. The i

notive behind this development was a desi.e to derive a more efficient and accurate method for predicting the influence of

)

elee-tric power generating units on estuarine heat budgets. The model has subsequently been adapted to the estuary (discharge basin) used as a reeleiving basin for thermal effluents discharged W

D e +

M

..4 s

w

-e

e-a n:

r-by the Crystal River electric power generating. facility of the :

Florida-Power Corporation._ In this application it was used-

' to predict the distribution of heat in the discharge basin resulting from the addition of a nuclear generating facility to the two existing fossil-fuel units. This prediction represents a maximum plant loading under summer conditions (worst case).

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L THERMAL ENRICHMENT MODEL Model Equations In the mathematical description of the water quality of an estuarine system the constituent mass balance equation becomes coupled with the long wave equations for the fluid mass.

If it is assumed that, in shallow estuaries, eddy transfer and turbulence caused by frictional stress vertically mixes the fluid mass and that the horizontal velocity field is independent of depth, the model can be considered as a two-dimensional system.

The simulation algorithm employed by the model incorporates the vertically integrated, two-dimensional momentum and mass conservation equations. These equations as applied by Palmer (in preparation) are as follows:

Conservation of fluid momentum 3_U_ - fV + g D a n + 1 (Tb_7s) = 0 (1)

U x

at 3x p

E - fU + g D an + 1 (Tb_7s) = 0, (2) at By p

l F

l

^

l, w.,

Conservation of fluid mass 3 + BU + BV = 0, (3) at 3x Oy and conservation of constituent concentration 3 (DO) + 3 (UO) + 3 (v0) - L (DAxd-St 3x By 3x 3x L (day h - DS = 0 (4)

By By where, at some point (x, y, z, t),

g E acceleration due to gravity in the (-z) direction p E fluid density f E Coriolis parameter U E x-component of the fluid mass transport vector 2

V E y-component of the fluid mass transport vector C

D E total depth n E surface elevation. relative to mean sea level O E constituent concentration A E x-directed eddy diffusion coefficient x

A E y-directed eddy diffusion coefficient y

S E-local source / sink of pollutant O

e e

O h

'y.

h Thetermsthandt are the x-and y-components, respectively, y

s of the bottom stress acceleration, and t and Ty are the surface stress components resulting from atmospheric winds.

In the'model, equations 1 thru 3 are solved by the finite difference method that Reid and Bodine (1968) used in their -

model of storm surges in Galveston Bay. Modifications made to the Reid and Bodine model involve only the inclusion of Coriolis effects and a blockage routine (Klausewitz,1973) for siculating oyster bars, sand bars, and spoil banks. The primary forcing function of the fluid mass is tidal and is simulated by a sinusoidal, fixed-amplitude function along the west boundary of the model. Surface stress terms are generated by Reid and Bodine's wind stress functions, and the bottom stress calculations are adapted from Leendertse's (1970) quadratic formulation.

Inputs resulting from local sources such as rivers and power plant discharges are simulated by addition of fluid head.

The solution algorithm employed by the dispersion model is based on the semi-implicit finite difference method suggested j

by Kwizak and Robert (1971). This approach allows some of the i

computational case of an explicit scheme (e.g. Klausewitz,1973) while permitting the larger time step of the implicit scheme (e.g. Leendertse,1970).

In a tidally driven estuary the dispersion of a conttituent will be accomplished more rapidly by advective processes rather em O

than by diffusive processes. In accordance with the Kwizak and Robert solution scheme the diffusion terms are. treated explicitly and the advection tems are treated implicitly. The implicit solution is a multi-operational approach similar to that used by -

Leendertse and Gritton (1971). The heat budget, as manipulated by the dirpersion model, is taken to be non-conservative with sources and sinks of heat representing power plant discharge and meteorological exchanges.

Frictional Stress Accelerations Although the tidal forcing function is the primary driving force in an estuary, wind stress can have a significant influence on the flow. In shallow estuaries, short term wind effects may even provide the dominate influence in the development of circulation. Because of this possibility, wind stress terms have been included in the model. The wind stress is calcualted (Reid and Bodine, 1968) as follows:

T = KW cos ($)

(5) 2 Ts, gg sin ($)

(6)-

where

%e a

w l

y W E wind speed at 10 m above the water surface

$ E angle between the wind velocity vector and the x-axis K E non-dimensional coefficient (Van Dorn, 1953) s K is specifically defined as

~

K=K for W $ We K=Ky+K2{l-Wj for W > W e

Wd where

_j

~

1 E 1.1 x 10 I

K I

K 2.5 x 10-6 t-2 s

i W E critical wind velocit'y (= 7 m sec-1) e The exact nature of bottom frictional resistance in free surface f a not known. _However, the phenomenon has been studied for channel flow by Chezy and Manning (Chow,1959) and found to be proportional to the square of the flow velocity vector. An extension to two-dimensional flow can be made by s

considering the componer.ts of the associated mass transport vector. Thus the bottom stress can be expressed (Leendertse,1970)

T = y U (U2, y )l/2 H-2 (7) 2 x

4 y )l/2 H.

2 2

T = y V (U (8)

Y

=,

d where y is a friction coefficient which i;s dependent upon depth and botton roughness.

Blockages In tidal estuaries, the circulation pattern is affected by the general geometry of the bottom as well as by the shear forces induced by bottom roughness. Of particular interest in the design of a mathematical model of estuarine circulation are obstructions that are submerged during one stage of the tidal cycle and are emergent at another stage.

?

In general, two-dimensional flow will result in the movement i

of water over the top of and around the ends of submerged obstructions such as oyster bars, sand bars or break waters. 'Rao and Shukla g

.(1971) assert that the variables pertinent to two-dimensional flow over an obstruction of rectangular cross section are as follows:

Water depth over the obstruction Height of the obstruction relative t6 the estuary bottom Width of the obstruction Direction of the obstruction relative to the flow direction Length of the obstruction normal to the flow Roughness of the obstruction's surface.

Klausewitz (1973) developed a relationship for blockages l

l 4

i y

of this type to be used with an exp?lcit finite difference algorithm (as is currently employed in the model). The assumption of Klausewitz' method is that U' = d g (9)

Ao where U E magnitude of the normal flow 4

U' E modified normal velocity A E cross-sectional area of the obstruction 3

A E cross-sectional area of the region (grid) containing o

the obstruction.

This assumption leads to the formulation of a modified velocity equation.

In component form the modified velocity is computed as (See Fig.1)

(

r.

U' = x U 1-L sin ($) + (H+n) L (10) r as D

As b

V' = x V l-L cos. ($) + (H+n) L (11)

, As D

As, where L E length of the obstruction H E depth of the obstruction surface relative to the mean sea level

~

-e

l V'

A

/V

. : v. /

~

..: x.

. i..

y. ;:',< 9 E

.:!'kIE U'

> AS U-->

= /.;. " ;

= -

- = =

.1/:

7

./

.: Z,::

4

^H

)\\

i.

h

/

Z---

y AS V

gg x

s f

U' '

'Ag U

i a

j V'_

Ao V

i i

Fig. 1.

Blockage geometry (after Klausewitz,1973).

N I

Y

f 4 E' angle of the obstruction relative to the x-axis e E proportionality constant (a function of the blockage width and surface roughness).

The results of modifying the velocity values when an obstruction is encountered is manifest in the calculation of r-the sea surface heights at that point. These heights then i

propagate the modified velocity information to the other calculation points in the succeeding determinations of velocities. The general circulation of the estuary is thus modified by the presence of obstructions.

Eddy Diffusion Coefficients The dispersion of a constituent is a function of the advection and diffusion processes associated with the constituent and the dispersing medium.

In an estuary the flow is variable, thus, the constituent will be " dispersed" in the direction of the flow but cross-sectional differences in constituent concentration will occur. Cross-sectional turbulent diffusion will then transfer the constituent from areas of higher concentration to areas of lower concentration. The magnitude of the dispersion coefficients employed in the model can therefore vary widely depending upon the particular area under investigation.

Elder (1959) in an attempt to develop a functional'

. relationship for the dispersion coefficient concluded that W

.P' cf major importance to the phenomenon are water velocity, depth and shear forces. Because of this relationship, dispersion in the direction of the mean flow (longitudinal dispersion) is found to be greater than the dispersion perpendicular to the mean flow (lateral dispersion).

The ratio of the dispersive transport to the advective transport over a finite section width can be expressed (Leendertse, 1970)

R = H AJ 3 0 = A 3_(In 0).

(12) x H U 0 ax U 3x Leendertse (1970) concludes that, even for large values of A,

x the ratio R is generally small.

However, at the locations of discharge of the constituent into the estuary (steep concentration I

gradient) R may become larger.

Since R is generally small, an isotropic dispersion can be assumed to exist that represents the effect of diffusive and I

turbulent mixing processes. Thus the following functional 8

relationship is assumed (Leendertse,1970):

j i

A = f (U, c, H) + D (13) x 1

w

= f (V, C, H) + D,

(14)

A 2

y EP

where D,

E isotropic dispersion coefficient fle2 adjustment function relating the effects of water velocity, depth and shear stress, i

l Heat Budget.

The heat budget of an estuary is affected by LLe prevailing meteorological conditions as well as by direct heat input by discharge of heated water. In any given time period the temperature (heat per unit volume) at some fixed point in an estuary will be 1.

raised, lowered, or remain constant depending on the flux of-heat throuth the water surface and on the mixing with surrounding water that occurs during that period. Thus, taking temperature j

(T) to be the modeled constituent 0 in equation 4, the heat flux through the surface becomes a part of the local source / sink term S.

4 The temperature change due to mixing is determined by i

solution of the constituent mass balance equation. The heat flux

' ~

through the water surface, can be expressed as 9H" (9sn + 9ata) - (9W + 9e + 9e)

(15)

{

i i

where l

FF c

qsn E_ net solar radiation flux qatm E het atmospheric' radiation-flux qw E water surface radiation flux qc E sensible heat flux by conduction and convection q, E evaparative heat flux.

q enters the model calculations as part of the source / sink H

term S.

The " energy received" terms qsn and gatm are measured together as total net incomming radiation qR.

These two terns are independent of the water surface temperature -(unlike the

" energy lost" terms: qe, qw and -qc) and crn be determined by an external program. -Since a single-layer, two dimensional model i

is employed, all net incoming radiation is assumed to be absorbed and distributed uniformily throughout the water column.

Assuming that the loss of heat due to the " energy lost" t

terms as well and that due to qR is distributed homogeneously

~~

throughout the water column allows calculation of the resultant temperature change (AT in *C) - as l

L l

AT = Aq i

C D (16) p where

i i

i 2

Aq E qH/cm surface area (in cal /cm )

D E height of the water column in cm C E the specific heat capacity of water p

The " energy lost" terms along with measured values of l

qR are needed for solution of equation 15.

The values of these I

terms can be determined as follows (Klausewitz et.al., 1974):

1 The evaporative heat flux q, is calculated (after Kohler, f

1954 and as adapted by TVA engineering personnel,1968) for an upwind station. The expresion is j

qe = Dw E HV (17) where E E rate of water loss per unit area due to evaporation (m/s)

NV E latent heat of vaporization (kcal/kg) 3 ow E _ water density (1000 kg/m ).

E is computed as E = 1.56 x l'O~9 U2 (*o - *2),

(18) where 2 E wind speed at 2 meters above the water (never U

less than 0.05 m/sec) f*

e E pressure Omb) of saturated water vapor at surface n

water temperature To e2 E pressure (rda) of water vapor 'in ambient air at 2 m at an upwind station All bodies emit radiation at a rate proportional to the i

fourth power of the absolute temperature (Ta) of their surface.

t The heat flux equation accommodates this phenomenon through l-I the radiation flux term qw. 'q,can be calculated by j

i l'

q,=ccTf (19)

~

where T ETo ('C) + 273* K g

c E 0.97; the emissivity of the water surface o E 1.36 x 10-11 kcal m-2

-1 K-4; the Stefan-see o

Boltzman constant.

Measurements of sensible heat flux qe have been made using Bowen's ratio R = go.

(20) 9e According to Neuman and Pierson (19667 R can be expressed as

.(= 0.49 p (T

.T9)

(21) m 1013 (en - e2) 4 -

e

~ yd

~

where i

p E.atmosphoric pressure (in mb)

T E temperature of the water at the sea surface o

T2 E temperature 2 m above,the surface of the water.

Solving. equations 20 and 21 for q,provides j

4 q,= 0.49 p (Tn - T9) ge.

(22)

~

1013 (e - e2) n The application of equation 15 as a source / sink term in the model is dependent upon the nature of the phenomenon under investigation. If a prediction of the net distribution of heated I

discharge waters after some time interval is desired, a daily f

mean value of qg may be appropriate.

However, if the effect of diurnal variations in qR are f interest, S must be taken as; I

time dependent, and a diurnally varying qH must be employed.

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4 1-CRYSTAL RIVER MODEL

+

Description of Modeled Estuary The estuary (discharge basin) adjacent to the Crystal River I.

electric power generating facility of the Florida Power Corporation is a gulf coastal region of North-central Florida (see Fig.-2).

As seen in Fig. 3, this region encompasses the area in which the withlacoochee River - Cross Florida Barge Canal complex encounters the Gulf of Mexico as well as the area in which the generating facility discharger heated effluents. The estuary is bounded i

north and south by dredging spoils, on the east by a salt marsh, and is open to the Gulf of Mexico on the west. The estuary itself is crisscrossed by several irregular strings of oyster bars which form barriers to water flow.

,s; The generating facility is presently operating with two fossil fuel units (u' nits I and II) with a nuclear generating unit (tinit III) to be added. The present effluent discharged by the facility is heated sea water. The nuclear unit s'.11 add radionuclide waste as well as increased. thermal effluent.

Assumptions The them.1 anrichment model described previously has i

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er Fig. 2.

Iccation of the Crystal River discharge basin.

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- CROSS-FLORIDA BARGE g

CANAL COMPLEX i

8 SALT MARSH C otSCHARGE BASIN t

Fig. 3.

Discharge basin and Withlacooch e River Cross Florida Barge Canal complex.

[

O D

been applied to the. discharge b6 sin.

The finite difference grid approximation (AS = 200 m) employed by the model is presented in Fig. 4.

The nature of finite difference approximations to continum problems requires that several conditions and limitations be imposed on the model. For the Crystal River Model the inputs and conditions are as follows:

a) The tidal forcing function is an M2 tide (12.42 hour4.861111e-4 days 0.0117 hours 6.944444e-5 weeks 1.5981e-5 months period) with a mean diurnal ra'nge of 1.05 m.

b) Wind etress on the water surface is. considered negligible (i.e. T* = T.s = 0) due to the short fetch from three directions, and diurnal variations in onshore-offshore winds.

c) The Withlacoochee River - Cross Florida Barge Canal complex is considered to be a ecmmon influence with a 3

-1 (median value of mean discharge of 56.69 m sec historical data).

d) The transport effects of long shore currents are neglected due to the presence of extensive dredging spoils.

e) The power plant's discharge rate is represented '.f

-1 a head gain of 40.38 m sec for units I and II and 3 sec-1 for units I, II and III (the intake i

83.29 m of cooling waters occurs outside the model boundaries).

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2 3 4 5 6 7 8 9 10 ll 12 i3 14,15 16 17 IS 19 20 El 22 23 24 25 26 27 28 29 30 Fig. 4.

Model boundaries and blockage locations.

ma q

e o Al Muuu2U1Lnlo W

.c t

f)

The discharge water is assumed to have a temperature rise above ambient of 6.39'C for units I and II and 18.06'c for units I,-II and III..These numbers correspond to maximum plant loading or worst case in terms of temperature rise, i

g) Oyster bars are treated as blockages.

h) Meteorological conditions are assumed to be static and are taken as daily averages for a sunmer situation.

(The data used were collected 8-15 June, 1973 were 9

averaged and are presented graphically in Fig. 5.

For daily averages see Table 1).

Initialization of the Crystal River Model was accomplished by simulating a full tidal cycle before " turning on the heat".

At the beginning of the second tidal cycle (max flood) the simulation of heated effluent began. The simulation was then i

continued for.4.25 additional tidal cycles or a real time equivalent of 2 days 4.8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months .

'Results i

l For purposes of reference, the discharge basin has been divided (according to natural features) into several sub-basins (Rodgers and Klausewitz,1975) as shown in Fig. 6.

The predicted distributions of the heated effluent released 1

i i

j e

m

a er

c

F

C 82-Dry Bulb Temperature 77-Wet Bulb Temperature.

25 81-76-

-27 24 80-75-

=

5 79-

. ji 74-5 26 g o

o g

1 23 E

[.78-f*73-h 77-25 72-

-22 76-71-24 75 8

12 16 20 24 0

4 8

12 16 20 24 70 0

4 Hours Hours 6-Wind Speed 10!8-Borometric Pressure 5-10l7-t 4-1016-

+

8 E

E 3-

$1015-e

=

.i,.

2 iL g

2-10I4-l-

1013-4 S.

I'2 l'6 2'O 2'4 4

8 l'2 - I'6 2'O 2'4 Hours Hours Fig. 5 Meteorologic21 data (June 1973).

e

-v

P O'

Table 1

. Data for Meteorological. Exchange Routine METEOROLOGICAL PARAMETER MEAN DAILY VALUE Water Temperature 30.50

C 7

Dry Bulb Temperature 26.16

'C Wet Bulb Temperature 22.93

C 4

Barometric Pressure 1014.89. mb

-1 Wind Speed 3.18 m,sec Net Incoming Radiation

0.058 kcal m-2

-1 3,e l

'l

Computed for a steady-state situation.

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i Fig. 6 Sub-basin identification map.

y

. r.~

e W-(units I and LI) into the discharge basin by the generating facility for varying stages of the tide are shown in Figs. 7 through 11.

The-contours represent temperature rise above ambient (30.5'C) and the high tide prediction in Fig. 7 is after 1 day 16.4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of real time discharge simulation. Each succeeding figure represents the predicted plume 3.1 hours1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months later than the previous figure.

High tide (Fig. 7)

For the most part, the plume is contained in sub-basin 1 and southern sub-basin 2.

The oyster bars separating sub-basins 2 and 3 seem to be forming an effective block along their western reach but cooler water is intruding into sub-basin 2 in the vicinity of the discharge canal.

Maximum ebb flow (Fig. 8)

As the discharge basin drains, the hotter water that was stored in sub-basins 1 and 2 enters sub-basin 3 across and around the eastern reach of the oyster bars separating sub-basins 2 and 3.

The maximum extent of the plume now extends westward into-sub-basin 5.

Low tide (Fig. 9)

Sub-basin 2 contains even less of the heated water than it contained during ebb flow. The plume has experienced additional I-i w

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UNITS I & II CALCULATED PLUME AT HIGH TIDE

%'4 TURN-ON PLUS I DAY 16 HRS. 22 MINS.

e s a

CONTOURS IN *C ABOVE AMBIENT.

n

' ?'

Fig. 7.

Calculated plume for units I and II at high tide.

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.n CALCULATED PLUME AT MAXIMUM EBB FLOW r

TURN-ON PLUS I DAY 19 HRS. 28 MINC.

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e s CONTOURS IN *C ABOVE AMBIENT '

I I

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Calculated plume for units I and II at maximum ebb flow!

r

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'o y \\ "u.a::\\lfr\\ Q 3 l 2- ~ "2 a e ( I UNITS I,IICIII S e s CALCULATED PLUME AT MAXIMUM EBB FLOW o TURN-ON PLUS I DAY 19 HRS. 28 MINS. CONTOURS IN *C A30VE AMBIENT 1 i Fig. 13. Calculated plume for units I, II and III at maximum ebb flow. E '.;fi:'i:*7Y*".'{ i,(} *..$ ' *? \\ i'y.0::. ff. . }. ~ y" ." ' 't *'. '+=~-?~~' ~

^

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e f.

m.. p 3 4 g@ ^ :(, - c h 2-5 i I g 4 .,T k 3

hf 4

s ~ s 2' E UNITS I, II CIII CALCULATED PLUME AT LOW TIDE TURN-ON PLUS I DAY 22 HRS. 35 MINS. CONTOURS IN 'C ABOVE AMBIENT-- u Fig. 14. Calculated plume for units I, II and II at t '.;; -ln';&j; :. ff.**ij[i;;:.\\ ^ \\ .... ; }^. ' ?f .i '. .- *. ::.] ' U = -- ~~ ~ k it ..d y 9. A/ hg o g, ll:-:.; i p *.

m.iomete,

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? ...E'~-l_9_. , '.) _.l'.Y.~.*'- ..-]* N 7m 2 ,p .o .,.;.=,2 4,. mpm. . a.. p. _ 95i m', gg f.' 4%

R' 6

.N .9 % ;g s ..( 5 e 3 3 n @g':i ( e i.tjL 2 a' ~' fis*; ae 4 / '-* ., S. /, 4 "a f 4 % P e 1 J.. ' V eQn *!:u, W. .m-3? 3 3 ~ l 2 h "Jg UNITS I,UCIII i g o CALCULATED PLUME AT MAXIMUM FLOOD FLOW TURN-ON PLUS 2 DAYS I HR. 41 MINS. w CONTOURS IN *C ABOVE AMBIENT / j 1 ~ Fig. 15. Calculated plume for units 1, II and III,at maximum flood flow. e k y ~, ~ ','?*jV/2.E. * ;'"i. k.. :*.'..' * *. u ..;i :' *. !':.l q .:gi)k.i.'.:. '-':*i ' - - - - - - " ~ y -,. ' ' ",

*,,*.,.l y * ~.

k .~ .y:-/-,.. l ,?. k?onR.

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y.;. /.:< r Nq l

l I e t / UNITS,1,U tIII ,a A ,,a-- s = 0 CALCULATED PLUME AT HIGH TIDE TURN-ON PLUS 2 DAYS 4 HRS. 47 MINS. 1 CONTOURS IN *C ABOVE AMBIENT 1. mm o ^%' J e e Ju e J. U 3 Fig. 16. Calculated plume for units I, II and III at high tide. r..

["

i 4"

is, however, considerably greater than that of the plume resulting from operation of only the fossil fuel units. High tide (Fig. 12 ) - I The plume is primarily in sub-basins 1, 2 and 3 but has ,,f already pene* rated sub-basins 4 and 5. There is also a substantial 1 amount of. heated water in Rocky Cove. .F Maximum ebb flow (Fig.13) 't i The plume is experiencing the same westward movement as ,I before (Fig. 8) but with a greater magnitude. Heated water has

r'

j reached the spoil island barricade on the north side of_ the i,

estuary. Low tide (Fig. 14) An extensive amount of heated water has now entered

t.

sub-basins 4 and 5, and a high concentration of heated water is found in sub-basin 3. Th'e plume has receded from Rocky Cove. Maximum flood flow (Fig. 15) l Again, as the tide waters flow back into the discharge basin, the plume is pressed back toward the shore. Sub-basins 5 and 3 are experiencing the most rapid reduction in heat concentration. \\- High tide (Fig. 16). l Sub-basin 1 is experiencing an accumulation of heated water due to the tidal flow, inhibiting advection away from the discharge !i. 3 SW 1,~ F point. The' enlarged plume area (relative to Fig. ~12) indicates . that a: steady, state situation has not been reached.. This. - deviation from the steady'; state is worse than for units I add II: due to the increased amount of heat being discharged into the ' - estuary. I ) G i 1 5 4 5 ~4 e 1. W w 9 0 . q-ev r ,n w-a v r i DISCUSSION For the results of the model to yield any useable information, the results must be compared with field observations of a "real" plume. These observations must be made when conditions similar to those imposed on the model exist. On 22 June,1974, two salinity-temperature-depth (STD) surveys were conducted in the dischargo basin (Eehrens and Rodgers, in preparation). The general meteorological and tidal conditions that existed on that day were in reasonable agreement with the model assumptions. The first survey (see Figs.17 through 19) was conducted in the morning during an ebb tide and the second survey (see Figs. 20 through 22) was conducted in the afternoon during a flood tide (see Fig. 23 for tide data)'. As can be seen by comparing Fig. 17 to Fig. 18 and Fig. 20 to Fig. 21 there was good vertical homogeneity of the plume during the entire tidal cycle. This condition further supports the. assumptions of the model (i.e. two-dimensionality). In addition to the tidal influence there are tw major sourece of flow into the discharge basin. These are the Withlacoochee River - Cross Florida Barge Canal complex and the I generating facility itself. It was assumed, for modeling l j, purposes, that the discherge of the barge canal complex was 3 -1 56.69 m sec This is a median discharge rate based on IL F t f 1 j -- ** \\ N ^ .rI -. ~~ ) . _., *N., pr, ns 5 g e" h \\, 33 5 P ^ a Q.,'.). g s .5 31.5 ,9 31.5 j x q~ ~ 1 . ' %e s 30.5 32.5 s 1* N g r -g'g,,% c A .e.&p.

l.p# -

,*c ~~ %>I .;o,o j e. s

s. Q o

= ^ t Or o e a 9 e. SURFACE TEMPERATURE: 22 JUNE 1974 OBSERVED PLUME AT EBB FLOW s e s = CONTOURS IN *C i I I i '~ Fig. 17. Observed surface temperature for unity I and II at ebb flow. c. t m. j ? _N - ll-l~&

~.i;h.h '$0

--k o F. ,.2 - e, .[.) ~ u.; c; p \\ '. e j,*" ,e 3.5 l .<y e %. 2 s b ,s

i l i g

[,, Q. \\. N 8 30.5 "s 30.5 'E 31.5

N'

/ d,

/

-= 32.3 31.5 s 30.5 g l ) %f l .,.,'sYi %

/

d# a 3 ) %l i , f ~. s!<p. 'a f lG ~ .o a ..a - @. e*' t' sa, y q e t. 1 METER TEMPERATURE: 22 JUNE 1974 ~~~ OBSERVED PLUME AT EBB FLOY/ f y CONTOURS IN 'C y::1:UTL ~ Fig. 18. Observed 1 meter tempera ure for units I and II at ebb flow. s. E e- ..p

f$

l.'

' ~ " ' i 1 j*'~\\ .. :

f. U, c

g..:.('.'i**...' \\'-"' '..q. "r.~. u, o_,Q s.-w m -l . - ) g ',~ n s .e ,,y*,,,

e 4

[ A.

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.ll s\\\\,/

g g t {, - N

,N.

K, s N u 2 4 25 p 7 p 27 es 0 /* 1 o n (,. .,6 {"%., ',). *e%D'if,, f .j i, ,u t-O \\ a 9 a t / SURFACE SALINITY: 22 JUNE 1974 L. p r s OBSERVED PLUME AT EBB FLOW CONTOURS IN 4 m -Fig. 19. observed surface salinity for units I *and II at ebb flow. \\w W f- " //.... ! )j ', . -i ..fl:;*. p* k ' "... ri l L.- -- --) g .s 'r p"'. h-v.e-meesrl 0.' ~ * '.t

M.

,,N ss.5. 1 m ~~~ ,l . f - lF- '.. 'i ~' % e e ~~, . 'A [

RM,-

J e g.'

s.*?: esk

's h,]. '8 'g ,s2.s \\ se e o Q7* c D. .j ' V) ~. ,e ss.s h f Y r* %g. rc .get a So(Cf~ -d w ~ so.s ff r '* ;* f{f ,a ,,- W,.--.- s= .r e j SURFACE TEMPERATURE: 22 JUNE 1974 >W OBSERVED PLUME AT FLOOD FLOW e s CONTOURS IN *C .) o rb o J c o Ju o J uu u. m i Fig. 20. Observed surfac'. temperature for units I and II at flood flow. F gi.... y ~ ,...l." ' j..T ;}. E ' y.E l0.. 1.. ) N N. '.~s. M[L_-. p.?.. mww

3

,\\ ..s.. ~~

j^..'.

'. ' _.~~s. 1 c -.=.. ~~~ .,,.'a.- ,/ j ug ?~~\\ -)a x, {; b w D w, f- ) r 3,., n.. .I .. t .g a _,g # '~ % ~ > Cfp :r 1s -s eb f .p v ? 4 e 9 I METER TEMPERATURE: 22 JUNE 1974 j .7 OBSERVED PLUME AT FLOOD FLOW o CONTOURS IN *C i E S 1 Fig. 21. Observed 1 meter temperature for units I and II at flood flow. w. t c .. :,... -j jj .J i .y Q........ i e. N L Q'p. - y y y/ o 28 i / \\ 4 > - ~. ../ / l tl ) 't.'; - __ _s 26 e f,,0

.C

..cc0 A i n ,6 i 19' /*i i .. g s c. -)/ -1 s\\ s. ' l 2l l. U* \\2 h gg 8 2 24 i ~ 1 27 i x 3,~ % u. J 7 N 26 j 4!. ' %r' / t ...g... n ~ i ~ o i SURFACE SALINITY: 22 JUNE 1974 '/ OBSERVED PLUME AT FLOOD FLOW e r CONTOURS IN 0 l_ l Fig. 22. Observed surface _ salinity for units I and II at flood flow. l l1 s 9 m l.5- - 1.5 1 1.0 - - 1.0 Cn 1 up T Z 11 [ 0.5 - LIJ - 0.5 [ s 1 \\ J MLW- -MLW J I I I I I l l 0 4 8 12 16 20 24 HOURS FIGURE 23. Tidal conditions on 22 June,1974 (data supplied by FPC). l' data supplied by the Southwest F1orida Water Management District. The discharge rate of the complex on the survey day was 21.24 3 sec-1 (data supplied by U.S. Army Corps of Engineers). m Surface salinity data (Figs. 19 and 22) indicate that the influence of the barge canal discharge qp the discharge basin was small. The generating facility discharges a fixed head of 40.38 m3 sec-1 (units I and II) and this is the value used in the model (units I and II). The thermal plume predicted by the model is well developed althouth it has not as yet reached steady state. Comparison of the model results with the field observations 1 indicates that the general distribution of the calculated and observed plumes are similar. Discrepancies arise from the use of daily averages for meteorological conditions, assuming a continuous, maximum plant loading and the use of uniform values for dispersion and friction coefficients in the model. A plume observed during the morning should be over estimated by the model when mean diurnal heating and cooling effects are used. Similarly, a plume observed in the late afternoon should ~ be under estimated (see Klausewitz, et.al.1974). However, these estimate errors will prevail only if the diurnal heat 1 Because the background (non-plume affected ambient) temperatures of the ebb flow (29.l*C) and flood flow (29.7'C) surveys differ from the background temperature of the model data (30.T C), contours of temperature rise above the background r S ald be considered (see Fig.25 for intake, non plume eifected, temperatures). 4 transfer between the estuary and the atmosphere is the dominate source of error. In additior. to night-time cooling, the generating facility operates at a reduced oroduction load during the early morning hours (Fig. 24). This reduce 4 plant loading. (electric power generation) results in a decrease in the amount of heat in the discharge effluent (see Fig. 25). The model assumes a continuous 6.39'C temperature rise for the discharge water which corresponds to a condition of continuous maximum plant loading. The closest approach to this temperature rise on the survey day occurred from 0900 to 2400 when the rise was about 6*C. Prior,to this time the temperature rise of the discharge, water was as low as 4.4*C. The effects of a mean meteorological assumption and continuous maximum plant loading tend to complement one another in increasing the plume size differences for the morning comparison and to oppose one another for the e.fternoon comparison. Thus the differences in plume size between field and model results should be much greater for the morning than for the afternoon predictions. These differences are due primarily to the effects of variable plant loading not manifest in the model (maximum loading results). If calculated and observed thermal plumes cover the same regions of a well mixed estuary then the ratio of the surface i 1 areas of the two plumes provides a quantitative measure of the 1 .l l 1 .:<;u... V 900 900 850 850 I 800 m 800 - e o 3 3 0 o O O e o 750 2 "llii 750 - 700 700 - 650 650 0 4 8 12 16 20 24 Hours Fig. 24. Plant loading on 22 June 1974 (data supplied by FPC). l L Per ' INTAKE TEMPERATURE r

c W 86 -

- 30 4 4 h85- \\ h 3 \\ 3 r - 29 s 84 - i a a a a i i O 4 8 12

16 20 24 HOURS DISCHARGE TEMPERATURE

-36 96 - u ^u o n $ 95 - -35 4 5 5 $ 94 - N U 93 - ~34 i e i i i O 4 9 12 16 20 24 HOURS DISCHARGE TEMPERATURE RISE

F

C v

-6 E N iE 10 - E N N g 9- -5 Ss e E W 2 8-E Y Y 4 i i i e i a 0 4 8 12 16 20 24 HOURS Fig. 25. Intake and discharge temperature on 22 June 1974 (data supplied by FPC). their relative " closeness in extent". Since the field data pointu do not cover the entire discharge basin, only those regions of the basin covered by the field survey can be compared. A study of the effects of diurnal meteorological variations en water bodies of various depths'was reported by Klausewitz 31_g1. (1974). It was concluded that for " deep" water bodies the effects o.! diurnal temperature variations could be neglected in thermal plume studies but that for " shallow" water bodies the diurnal variations are very important (see Fig. 26). The mean depth of northern sub-basin 2 (see Fig. 6) is 1 meter (Rodgers agt gl., 1975). Fnom Fig. 26 it can be seen that a diurnal temperature range of 4*C can result in this sub-basin, from meteorological variations. It is therefor nessessary to establish some criterion for differentiating between heated effluent water and meteorologically heated water. Since the ebb flow survey was conducted shortley after the period of maximum cooling, it will be assumed that the plume present at this time was established entirely by heated effluent. Comparison of Figs. 17 and 19 shows that the ebb thermal plume is in a region bounded on the north by the 24*/.. salinity isopleth. Thus, assuming the majority of plume movement to be the result of advection, the 24*/.. salinity isopleth is taken'as the boundary between the heated effluent water and the lower salinity water heated by meteorological processes. 'h yd m

F

'C 86- -30 85-W -29 W Z84-m o o H E 83-W W Q O 2 -28 s. W 82-W H H s 81- -27 i i i i i i i i i 4 8 12 16 20 24 HOURS op

C 22-

-12 1 20- $18- -10$ 2 z < 16-4 " 14 - -8 % ~ w 12-w m -6 m a 10- ,a H 8- -4 <m gw 6-w a.

o. 4 -

s 2 _. 2 W W F 2-H i e i i i i i i i e i i 2 4 6 8 10 12 FEET ~ TIGURE 2t' Thermal budget calculations (after Klausewitz el al_., 1974). e i .i Using the -above boundary restrictions, t'.. areas of the i calculated and observed plumes for units I and II were computed. These areas and their ratios (calculated to' observed) are presented in Tabic 2 The cumulative ratio of the pitae areas for the ebb flow are in gene al agreement with the expected results. However, there is a significant departure from the expected results in the 4-5'c plume area. This results, primarily, from three things: first, peak plant loading - (see Fig. 14) occurred approximately 4 one hour prior to the ebb flow survey;.second, the range of the i ebb tide, during which the survey was conducted, was substantially

i' smaller than the range of the model ebb tides and third, the discharge channel representation in the model is four times the actual discharge channel width.

The observed plume was thus composed of effluent that had j e been discharged earlier in the morning with a lower temperature rise and of effluent that had been. heated just before the survey to a point that approached the maximum temperature rise employed in the model. Because of the relatively small ebb tidal range if on the' survey day, the circulation and thus mixing associated with the observed plume would have been of a smaller-magintude than the model circulation and mixing respectively. These considerations, along with the enhanced channelization caused .e .by the relatively narrower " actual" dischcrge channel, result in b !}- l.' V r-i i e Table 2 Plume Areas for Units I and II 2 2 Interval ('C) Observed (km ) Calculated (km ) Ratio (calculated / observed) Dis. Cum. Dis. Cum. Dis. Cum. Dis. Cum. Ebb Flow [ >6 >6 5-6 >5 .01 .01 4-5 >4 .42 .42 .05 . 06 .11 .14 3-4 >3 .45 .87 .34 .40, .76 .46 2-3 >2 .57 1.44 .99 1.39 1.74 .97 ^' 1-2 >l .64 2.08 1.63 3.02 2.55 1.45 F?ood F3cw >6 >6 .03 .03 .03 .03 1.00 1.00 5-6 >5 .11 .'14 .15 .18 1.36 1.29 4-5 >4 .07 .21 .12 .30 1.71 1.43 3-4 >3 .34 .55 .21 .51 .62 .93 2-3 >2 1.27 1.82 1.13 1.64 .89 .90 1-2 >l 1.72 3.54 1.74 3.38 1.01 .95 pr I the elongated and larger 4-5*c plume area of the observed plume (see Figs. 8 and 17). Such reduced mixing also resulted in a smaller volume of water in the 1*-3*C temperature range. The occurrence of the above phenomena suggest that the calculated plume areas for the lower temperature rise contours should be greater than those of the observed plume. As can be seen in Table 2 this is the case. The flood tide range and discharge temperature rise for the survey day were similar to those of the model, thus the predicted and actual plume areas should be much closer.

Indeed, the cumulative ratio values of Table 2 are quite close.to the value 1.0.

Here again, the greatest departure from the expected results accurs for the 4-5*c plume area. In this case, though, the calculated area is larger than the observed area. It is quite likely that such differences are due in large part to a i lack of resolution in the field observations in the shallow mud flat area north of the discharge channel. It is quite significant that the accuracy was this good for the flood tide comparison since the actual and assumed conditions were so similar. With a reduction in the width of the discharge channel representation (by blockage routine etc.) and a matching of tide ranges and discharge temperature rises, it is expected that the model results will also closely approximate the observed ebb flow results. Greater resolution of field observations l l pr 4 4-will also be necessary to better delimit the higher temperature rise plume areas. Additional errors can hnter into model predictions from the numerical approximations of continuum equations. To obtain an estimate of these errors mainfest in the Crystal River model a heat " conservation" routine was developed to Reep track of all legitimate losses and gains of heat. As a result, it was determined that a heat " conservation" error of less than 2s occurred over the 4.25 tidal cycle period that was modeled. The calculated plume characteristics for units I, II and III, result from the same meteorological and tidal input conditions 3 -1) as for units I and II. A larger discharge head (83.29 m sec was used as the input from the generating facility. The above comparison indicates that the predicted plume-resulting from operation of all three units should provide a description

r of the expected "real" plume under maximum plant loading and mean summer meteorological conditions. These predictions represent then " worst case" thermal distributions for four tidal phases.

Since the plume information is available at the same points throughout the model grid for the calculated results for units I and II and for the calculated results for units I, II and III, plume areas for both predictions were camputed for the entire modeled region. These areas and their ratios are presented in Table 3. [ i ! ~ i . Table 3 Plume Areas for Units I and II and for Units I, II and III Units I & II Units I, II & III Discreet Cumulative Discreet Cumulative Maximun Ebb Plow .05 .05 >8 .40 .45 7-8 i 6-7 .11 .11 1.01 1.46 5-6 .32 .43 2.43 3.89 4-5 .21 .64 1.72 5.61 3-4 .35 .99 2.79 8.40 2-3 1.43 2.42 2.41 10.81 1-2 5.28 7.70 3.43 14.24 Lny Tide >8 .02 .02 7-8 .33 .35 6-7 .09 .09 .90 1.25 5-6 .32 .41 2.72 3.97 4-5 .31 .72 2.69 6.66 3-4 .59 1.31 3.33 9.99 2-3 1.29 2.60 4.37 14.36 1-2 3.79 6.39 5.26 19.62 P i 6 e t L. gr 0 Table 3 cont. Units I & II Units I, II & III Discreet Cumulative Discreet Cumulative Maximum Flo~3 Flew 4 .03 .03 >8 7-8 .44 .47 6-7 .12, .12 .61 1.08 5-6 .24 .36 1.18 2.26 4-5 .18 . 54 3.74 6.00 3-4 - 1.14 1.68 2.65 8.65 2-3 2,41 4.09 2.51 11.16 1-2 2.76 6.85 4.60 15.76 High Tide >8 .09, .09 7-8 .54 .63 6-7 .14 .14 .31 .94 5-6 .25 .39 1.10 2.04 4-5 .28 .67 2.33 4.37 3-4 .71 1.38 2.79 7.16 2-3 1.82 3.20 2.55 9.71

l l-2 4.90 8.10 3.17 12.88 r

i I l I' l h g e i CONCLUSIONS 'A model has been developed to predict the transport and diffusion of thermal effluents discharged into shallow, barricaded estuaries. g The model has been adapted to the estuary adjacent to the Crystal River electric power generating facility of the Florida Power Corporation. Comparisons of model results with field observations made under conditions similar to those imposed on the model have been favtrable. The model has also been employed to predict the distribution of the thermal effluent that will be discharged into the estuary after the addition of a nuclear electric generating unit. Problems of a similar nature in other estuarine environments can be readily approached by the simulation algoritin (sed in the Crystal River Model. i. [ t e g. M~ Rcferences Cited Behrens, Paul J. and Bruce A. Rodgers, In preparation. Independent Environmental Study of Thermal Effects of Power Plant Discharge, Technical Report #9, Dep. of Mar. Sci., University-of South Florida, St. Petersburg, Fla. l Chow, Ven Te, 1959. Open-channel Hydrau1ics. McGraw-Hill [ Book Company, New York, N.Y. 680 pp. Elder,,J. W., 1959. The Dispersion of Marked Fluid in Turbulent Shear Flow. Journal of Fluid Mechanics, Vol. 5, pp. 544-Klausewitz, Ronald H., 1973. Diffusion Model for a Shallou, Barricaded Estuary, M. A. Thesis, University of South Florida, 71 numb. leaves. Klausewitz, R. H., S. L. Palmer, B. A. Rodgers and K. L. Carder, 1974. Natural Heating of Salt Marsh Waters in the area of the Crystal River Power Plant. Independent Environmental Study of Thermal Effects of Power Plant Discharge, Technical Report #3, Dept. of Mar. Sci., University of South Florida, St. Petersburg, Fla. 31 pp. Kwizak, M. and A. Robert, 1971. A Seni-implicit Scheme for Grid Pof.nt Atmospheric Models of the Primitive Equations. Monthly Weather Review, Vol. 99, pp 32-36. Kohler, M., 1954. Lake and Pan Evaporation, in Water Loss Investigations, Lake Hefner Studies, Technical Report, U.S.G.S. Prof. Paper 269. 1 Leendertse, J., 1970. A Water-Quality Simulation Model for Well-Mixed Estuaries and Coastal Seas: Volume I, Principles of Computation. ' Rand Corporation, RM-6230-RC, 71 pp. Leendertse, J. and E. Gritton, 1971. A Water-Quality Simulation Model for Well-Mixed Estuaries and Coastal Seas: Volume II, Computation Procedures. Rand Corporation, R-708-NYC, 53 pp. Neumann, G. and W. Pierson, Jr.,1966. Principles of Physical Oceanography. Prentice-Hall, Inc., Englewood Cliffs, N.J., 545 pp. 't ,q -r gr e I i Palmer, S. L., In preparation. A Semi-implicit Dispersion Model for Shallow, Barricaded Estuaries. M.A. Thesis, University of South Florida, St. Petersburg, Fla. Rao, S. and M. Shukla, 1971. Characteristics of Flow Over Wiers of Finite Crest Width. J. Proc. Hydr. Div., Am. Soc. Civil Engr., Vol. 97, No. Hy 11, pp. 1807-1816. Reid, R. and B. Bodine, 1968. gnumerical Model for Storm Surges In Galveston Bay. Proc. J. of Waterways and Harbors Div., Am. Soc. Civil Engr., Vol. 94, No. WW 1,-pp. 33-57.

Rodgers, B.,

R. Klausewitz and T. Keller, 1975. Recults on Bathymetry and Bottom Type Analysis of the Crystal River Power Plant Discharge Baisn. Independent Environmental Study of Thermal Effects of Power Plant Discharge, Technical Report #5, Dept. of Mar. Sci., University of South Florida, St. Petersburg, Fla., 30 pp. TVA, Division of Water Control Planning Engineering Laboratory, 1968. Heat and Mass Transfer Between a Water Surface and the Atmosphere Norris, Tenn., 98 pp. Van Dorn, W., 1953. Wind Stress on an Artificial Pond. Journal of Marine Research, Vol. 12, No. 3, pp. 249-276. / t 9 9 WF .

ML19319D132

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