ML19317F081

Reactor Coolant Flow Evaluation, Preliminary Rept

ML19317F081
Person / Time
Site:	Oconee
Issue date:	08/23/1973
From:	DUKE POWER CO.
To:
Shared Package
ML19317F074	List: ML19317F079 ML19317F081
References
NUDOCS 8001080771
Download: ML19317F081 (6)

Text

' UNIT 1 E ,IOR COOLANT FLOW EVALUATION c '

Preliminary Report

d.

• August 23, 1973

_ Introduction .

Oconee Unit 1 was designed for a minimum primary coolant flow rate of 131.32x10 6 p:unds per hour. A greater flow rate than the minimum is expected, however.

Wile this will afford excess DNB protection, a flow rate of 110.8% design flow has been specified by the Babcock & Wilcox Company as the upper limit to avoid c:re lift at the end of life.

A test was performed during the Power Escalation Sequence at the 75% full p:ver plateau to verify that the magnitude of the primary system flow is within ceceptable limits.

The details of this test are delineated herein.

,F=aluation The ters.

basis of the flow calculation is a calorimetric around the two steam genera-Thermal-hydraulic data was monitored for an hour on July 29, 1973, properly i cveraged, and substitued into the heat balance equation described below to provide primary flow.

k Figure 1 is a schematic of a steam generator with its associated coolant flow '

1 cops; the dotted line represents the control. volute for the darivation of the cciorimetric equatien. Since the enersy entering the volume must leave it in scme form, the following balance for the A generator can be made. s 1(+ 1 =

1(+ + Id r

A similar equation exists for the B steam generator. Both can be scived for primary coolant system flow and are presented below.

~

P

=

(l( - Ih) + K^ ( 11 - If) + K

~

~

Precision thermocouples and dead-weight gages were installed on the feedwater and '

ateam lines to measure Precision manometers were used to measureemperatures and pressures to calculate enthalpies.

the pressure drop across the cali-brated Bailey flew nozzles for the'feedwater and steam flow determination. The plcat process computer was used to monitor the primary side temperatures and prcssures and feedvater temperature. -

Manometer readings were taken every two minutes for the duration of the test.

Stsam secondary side temperatures and feedwater pressures were recorded on a five minute interval while primary side temperatures and pressures arid feed- ~

-water temperature were =onitored on a 15 second basis. The data was averaged cnd'the flow and enthalapies were calculated. .

(

\ \

- .---_ - - - - - - - - ~~

..-7 -7 j 8001080 ( /(

The heat lors term rey ents tha surf ace radiation a- or convection from the (uricen, cf the piping and the steam generators. This term has minor signifi-ccnca but is included for completeness. Its magnitude is taken as 0.724 and 0.787,million BTU /hr for loops A and B, respectively.

Table 1 is a listing of the average values of the data collected during the test. The calculated enthalpics and flows are displayed in Table 2. The flow equation is shown below with the proper values inserted and the primary flow noted.

W = (1251.03 - 415.28) 4.0815 + 0.724

• 6 609.00 - 561.31

+ (1251.69 - 415.28) 3.9642 + 0.787 x 10 6 609.27 - 561.20

= 140.34 M lbm/Hr The error analysis for the above flow value is derived in Appendix A. The result of the error analysis yielded a band of + 1.146 M lbm/Hr.

Since minimum design flow is 131.32 M lbc/hr at rated power unich corresponds 6 to 130.2 M lba/hr at 75% power, the censured flow and experimental error is 107.8 + .82 as expressed in percent.

Safety /.nalysis The minimum RC system flow rate shall be the FSAR basis of the 100% (131.32 x 106 lb/hr, minimum design flow at rated pcver) plus 2.3% excess for bypass due to removal of 44 orifice plugs. This flow rate is established as the

_ minimum flow rate to meet the DNBR requirements stated in the FSAR. Therefore, the minimum flow shall be 134.34 x 100 lb/hr at rated power.

, . i The maximum reactor coolant system flow rate is 110.8% of the minimum design flow rate based on fuel assembly lift limitations. This 10.8% excess flow design limit is determined by utilizing experimental evidence of fuel assembly' hydraulic resistance characteristics and the maximum expected flow rate for any fuel assembly based on flow distributions from the Vessel Model Flow Test. This maximum allowable flow rate is bas'ed on the more limiting end-of-life conditions.

The measured system pressure loss is lower than predicted and represents a design conservatism. Also, the modification of the reactor vessel and internals resulted in a reduction c the reactor vessel unrecoverable pressure loss. The reduction in reactor vest 1 pressure loss due to the internals changes is approximately 4 psi at the design flow rate. (Reference BAW-10037, Rev. 2, November 1972, " Reactor Vessel Model Flow Tests.") These two points account for the actual RC system flow rate being above minimum l design flow rate. -

Therefore, the reactor coolant system flow including possible measur.cment error for Oconee 1 is within acceptabic limits.

! {

i! l l

1

l

.ABLE 1. AVERAGED DATA Loop A Loop B s

Main Steam, Temperature, 'F 590.34 590.80 Pressure, psia 911.73 912.22

' Feedwater, Temperature, 'F 436.47 436.25 Pressure, psia 942.61 939.00 AP,'ppi: Tap 1 35.64 35.25 Tap 2 35.95 33.32

. Hot Leg, Temperature, *F 596.60 596.86 Pressure, psia 2122.0 2141.7 Cold Leg, Temperature, 'F 560.997 560.945

. Pressure, psia '

2089.4 2109.1 1

TABLE 2. HEAT BALANCE DATA Enthalpies (BTU /lbs) Loop A Loop B Hain Steam 1251.03 1251.69 Feedwater '

415.28 ,

415.28 Hot Leg 609.00 609.27 Cold Leg 561.31 561.20 Feedwater Flow Gi lbm/Hr) 4.0815 3.9642 Heat Losses 0.724 0.787 l

1 l

g6 e 4

I i

. t -.3-i 1

,, - ,, c > ~ =

9

~

, - TIGURE 1 LOOP i STEAM GENER' A 6

MP I!OT LEG W = Total Primary Coolant Flow p

M = Loop i Primary Flow 11 11 P f ~7 w 1

T g= Loop i ilet Leg Temperature / \ STEM I 1>4i P = Loop i llot Leg Pressurc $ T , P,

' i l li HEAT LCSSES g = Loop i llot Leg Enthalpy FEEDh'ATER i

Tc"L P i Cold Leg' Temperature ( l 1 \ ' I I P = Loop 1 Cold Leg Pressurc c FPi-F

.\ /

i N /

H = Loop i Cold Leg Enthalpy '

_.. c T

i- P i COLD LEG c c V

Tf=LoopiSteamTemperaturc

• i 4

P, = Loop i Steam Pressure i

11 8

= Loop i Steam Enthalpy ,

i l Tp= Loop i Feedwater Temperature t 1 Py= Loop i Feedwater Pressure j i

i 11 7 = Loop i Feedwater Enthalpy My = Loop i Feedwater Flow

i K = Loop i lleat Losses

. l 4_

l~, i t

APPENDIX A The, basic flow equation from Figure 1 is as follows:

Wp = (1 -1 ) + }[ +

(H - 1() dp+ K 1(- - 11 or W = W(X , X ' * * *

• X ) .

y 2 n and dW = "

6W

$=1 6Xil Therefore dW = 1 -I d + d + d Ifg - II 1( - 1 _ (6 l  !

6P^

)

F f_6th T A d T~ ~

p + 2[

61 dP A\

-1 6 A 6P p p }1

__ (I -I )k + 1 (0I dT^ + I dP^

(1 -1 ) A (6 6P

+ ~

} +

dT^

- * - + aP A

C (1 - Il^}

C 0 C

k

, dK H - 11F NF 1 - 11^

__ S l - 11 d[ + _ f6H

__S_ dTg B

+ 6H S

_ dP g B

g -H C \6T3 6P

~

dT + B 0 H -H F F C ( 61 6P dP),- dTH+ dP '

(1(-11 )2 6T 6B p

)

+ ("S

+ H dT + dP + dK (1 - 11 ) 2 _

} 6T 6P C) -1, O

h' t

• an b2 replaced by finite diff nces,AT[, representing

.The diffsrentials, dT The measurement

• th3 trcuret.ent. tolertr. for each variable'substituto tol;rcncca ara giv:n balows

'^ -

+ 0.5'F

- Main Steam Temperature .

, 4

- 1 psi Main Steam Pressure Feedwater Temperature + 0.5'F Feedwater Pressure

+ 1 psi i + 0.5%

Feedwater Flow RC Hot Leg Temperature + 0.25'F

+ 25 psi RC Hot Leg Pressure RC Cold Leg Temperature + 0.25'F RC Cold Leg Pressure + 35 psi Ambient Heat Losses +- 50%

for the feedwater flow and

! The heat balance The values data from forTable 2 isof the rate substituted change with respect to the differential j enthalpies.

are substituted for the partial derivation.

The terms of AWp are the squared, summed,and the square root taken. The terms represent the error in f eedwater flow, steam temperature, steam pres: 0:c, feedwater temperature, feedwater pressure, reactor coolant hot leg tey erature, reactor ecclant hot leg pressure, reactor coolant cold leg temperature, reactor coolant cold leg pressure, and ambient heat loss measurements.

4  %

4 e

e e- g

-t .

- 6-L_