ML20058N636

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Rev 0 to Engineering Analysis, EDG Cooling Water Pump Net Positive Suction Head Requirements
ML20058N636
Person / Time
Site: Big Rock Point File:Consumers Energy icon.png
Issue date: 04/19/1993
From:
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML20058N620 List:
References
EA-SC-92-026-02, EA-SC-92-026-02-R00, EA-SC-92-26-2, EA-SC-92-26-2-R, NUDOCS 9310200078
Download: ML20058N636 (10)
v • d • e


Text

f BIG ROCK POINT NUCLEAR PLANT ENGINEERING ANALYSIS WORKSHEET EA-SC 02 6- 02 PAGE 1 OF 9

~_-, _

REVISION 0 i

EDG COOLING WATER PUMP NET POSITIVE SUCTION HEAD l

Title:

REQUIREMENTS E

INITIATION AND REVIEW

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III OBJECTIVE: To check the effect of SC-92-026 on the design of the Emergency Diesel Generator (EDG) cooling water pump suction piping to ensure there is adequate net positive suction head available at the new operating conditions.

REFERENCES:

1. EA-EDSFI-C0C-8-02
2. EA-EDSFI-COC-8-01 ATTACHMENTS:
1. Graph of Water temperature verses NPSH at 88gpm
2. Graph of Water temperature verses NPSH at 70gpm From T7-28 performed on 3/17/93 after the installation of a new suction screen and change out of the suction check valve the following values were recorded:

PI-834 suction pressure was 13 inches Hg vacuum PI-836 discharge pressure was 13.7 psi 9310200078 931011 PDR ADOCK 05000155 G

PDR L

1 BIG ROCK-POINT NUCLEAR PLANT ENGINEERING ANALYSIS WORKSHEET EA-SC-92-026-C2 PAGE 2 OF 9 g,_

REVISION O 1

The new flow rate and velocities will be calculated using the equations from page 3 of EA-EDSFI-C0C-8-01 P, = 13.7 psi

'59" 144P' 34"'

' 2g __

+

= d7.215 + 4.757 P, = 8.51ft / sec.

V = 131.24 ( 12 62.4 24 j V* sf(2.06,{2)

- = 88.4gpm G = 0.002228ft' / sec/ gpm From EA-EDSFI-C0C-8-02 CALCULATION for Net Positive Suction Head Available (NPSH,)

-H

+ H, - Hg yp NPSH,= Hge,3

1. H Pressure on surface of water (atmospheric) wos>=

= 14.7 psia X 2.307 ft/ psia = 33.9 ft. of water 2.

H,= Static elevation of water above pump centerline 578 ft. - (589 f t + 3 f t) = -14.0 feet

=

3. H Vapor Pressure of the liquid @l00 deg.F vp=

(100 deg F was chosen since the maximum temperature of the lake in the summer is approximately 75deg F and the temperature rise of the water through the condenser is approximately 25deg F)

= 0.94924 psia X 2.307 ft/ psi = 2.19 feet l

H = Head loss f

4, this will be calculated with the following changes to the K values listed on page 5 of EA-EDSFI-COC-8-02:

check valve K= 2.1 Heating Element 1/2" rod in 2" pipe 144" long (from actual measurements taken 3/17/93)

(%(2.06)' - %(.5)')4/y = 1.997" A-A.

d

=

=

g 2

y 1 =.021* 144" =1.51 pipe friction loss: K = f D 1.997" 1

-I

BIG ROCK 1 POINT NUCLEAR PLANT'

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ENGINEERING ANALYSIS WORKSHEET EA-SC-92-026 PAGE 3.OF 9 REVISION O

~

Pipe - new total length of pipe = 142.5" a

pipe frictionloss X = f D =.021* 142.5" =1.45 l

2.06" H = K

  • V,' + K
  • V

f i

2 28 28 pipe V, = 0.408Q =.408* 88.4(2.06), = 8.5ft / sec d,

K, =.57+.3+.27 + 1.14 +.16 + 2.1+.78 + 1.45 = 6.77 pipe with heater V = 0.408Q * '408*88.4 = 9.04ft / sec d

(1.997)2 2

2 K = 1.51 2

6.77 * (8.5)*

1.51*(9.04)'

H=

+

= 7.6 + 1.92 = 9.52 2g 2g NPSH, = Hm + H, - H, - H, NPSH, = 33.9'-14'-9.52'-2.19'= 8.19 feet i

From EA-EDSFI-C0C-8-02 The NPSH required for the new flow conditions 88gpm-60gpm)

NPSH' s (7 - 4.5)* ((80gpm - 60gpm) + 4.5 = 8fect

/. NPSH, 2 NPSH, @88gpm flow,T = 100' F and Lake elevation of 578 feet CONCLUSION The addition of the new suction strainer and check valve have increased the pump flow from approximately 70 gpm (measured during the last TR-84 test) to 88.4 gpm (calculated from the T7-28 data). This change is due to less restriction to flow through the check valve. The net positive suction head available is greater than the net positive suction head required the present configuration is therefore considered acceptable for continued use. It is recommended however that an orifice be placed in the cooling water pump discharge to throttle the flow to approximately 70gpm. This will increase the net 1

positive suction head available to the pump and allow the pump to be

BIG ROCK POINT NUCLEAR PLANT ENGINEERING ANALYSIS WORKSHEET EA-SC 02 6- 0 2 PAGE 4 OF 9 REVISION O operated at lower lake levels than those presently allowed.

is very close From the above calculation it appears that The NPSHa to the required NPSH. This is true at the limits of 578' lake level and 100 deg water. It should be reconized that at present we are operating at a lake level of approximately 580' and an inlet temperature of 60 deg. Using these values, from Attachment 1 it can be seen that NPSHa is approximately 4' greater than NPSHr-CALCULATION FOR PI-834 PI - 8 3 4 = h,,,, + h% + h,,,

f

+, V,'

h, = K'V'*

K 2g 2g K, =.78+.021* 47[06,, = 1.26 K = 1.51 + l l% = 2.08 2

1.26(8.5)'

2.08(9.04)'

h=

+

= 4.05 2g 2g h" = V (9.04)'

2

=1.27

=

2g 2g h, = (17g2, + 589 - 580) = 10.4' PI-834 = 4.05 + 1.27 + 10.4 = 15.72 feet = 13.85/nches Hg CONCLUSION The suction pressure readings taken on 3/17/93 agree very well with the above calculation. From the above calculation if we substitute 578 feet as the lake level it would increase the suction pressure to 15.6 inches Hg. This is greater than that allowed by the current acceptance criteria of T7-28. It is believed however that the current acceptance criteria is conservative and there are no plans at the moment to change the acceptance criteria.

BIG ROCK POINT NUCLEAR PLANT ENGINEERING ANALYSIS WORKSHEET EA-SC-92-026-02 PAGE 5 OF'9 i

y REVISION 0 CALCULATION FOR ALLOWABLE LAKE LEVEL 670gpm FLOW t

The following calculations will show the effect of throttling the discharge flow to 70 gpm Conditions:

1. Flow =70gpm
2. Water Temp =100 deg.F P

Net Positive Suction Head Available (NPSH,)

+ H, - Hg yp

-H NPSH,= Hg,,

1. H Pressure on surface of water (atmospheric) ms > =

14.7 psia X 2.307 ft/ psia = 33.9 ft. of water

=

2.

H,= Static elevation of water above pump centerline

= X ft. - (589 ft + 3 ft) = X-592 feet 3.

H Vapor Pressure of the liquid @l00 deg.F vp=

= 0.94924 psia X 2.307 ft/ psi = 2.19 feet H = Head loss f

4, this will be calculated with the following changes to the K values listed on page 5 of EA-EDSFI-COC-8-02:

Check valve K= 2.1 Heating Element 1/2" rod in 2" pipe 144" long (from actual measurements taken 3/17/93) d,, =

A -A. 4/.=

%(2.06)'- %(.5)')4/. = 1.997" g

2 1 =.021* 144" =1.51 pipe friction loss: K = f D 1.997" Pipe - new total length of pipe = 142.5"

/

pipe fiiction loss K = f D =.021* 142.5" =1.45 2.06" H = K,

  • V '1- + K
  • V-

f 2

2g 2g

.I j

BIG ROCK POINT NUCLEAR PLANT.

ENGINEERING ANALYSIS WORKSHEET EA-SC-92-026-02 PAGE.6 OF 9 g,_

REVISION O 4

pipe V, = 0.408Q =.408* 70(2.06), = 6.73ft / sec d,

K, =.57+.3+.27 + 1.14 +.16 + 2.1+.78 + 1.45 = 6.77 j

pipe with heater V = 0'408Q _.408* 7 = 7.16ft / see f

2 d,

(1.997)

K = 1.51 2

6.77 * (6.73)'

l.51* (7.16)'

i H=

+

= 4.76 + 1.20 = 5.96 I

2g 2g L

NPSH, = Hm + H, - H, - H,, 2 NPSH, NPSH, = 33.9'+(X-592')-5.96'-2.19'2 6.4 feet X 2 592 - 33.9 + 5.96 + 2.19 + 6.4 X 2 572.7 feet Note: pumplooses suction @ 574.5fect Calculation for PI-834 070gpm flow PI-834 = h% +h,,,w,,+h,

+, V,'

h, = K,V,' K 28 28 K, =.78+.021* 47[06. = 1.26 K, = 1.51 + 1 l% = 2.08 h = 1.26(6.73)'

2.08(7.16)*

+

= 2.54 2g 2g h, = V (7.16)*

2

=.796

=

2g 2g h, = (17g2',+ 589-580) = 10.4'

)

PI - 834 = 2.54 +.796 + 10.4 = 13.74fect = 12. linches Hg j

@574.5' PI-834 = 2.54+.796+ 15.92 = 19.26 feet = 16.96inchesHg j

@ PI-834 = 14 inches Hg Lake level = 577.86

BIG ROCK POINT NUCLEAR PLANT

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ENGINEERING ANALYSIS WORKSHEET EA-S C 0 2 6- 02 PAGE 7 OF 9 REVISION 0

~

From the above calculations it can be seen that by throttling the discharge flow to 70 gpm there will be greater NPSHa for the purp. The calculation for PI-834 shows that the present acceptance criteria for T7-28 will still be valid. A pressure of 14 inches Hg at 70gpm would indicate a lake level of approximately 578 feet which is well above that required to maintain adequate net positive suction head. is a graph of water temperature verses NPSH for a flow of 70 gpm

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