ML20148J188

Rev NPSH Calculations for RHR & Containment Spray Pumps Operating in Recirculation Mode.Verifies Effectiveness of the Containment Sump & Describes Constr of 1:4 Scale Physical Model W/Test Results

ML20148J188
Person / Time
Site:	Sequoyah
Issue date:	10/27/1978
From:	TENNESSEE VALLEY AUTHORITY
To:
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ML20148J126	List: ML20148J121 ML20148J175 ML20148J181 ML20148J188
References
NUDOCS 7811150199
Download: ML20148J188 (9)

Text

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l REVISED NPSH CALCULATIONS FOR THE RHR AND

. CONTAINMENT SPRAY PUMPS OPERATING.IN THE RECIRCULATION H0DE '

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October 27, 1978 4

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' Objective The purpose of these calculations is to confhm that the net position suction head available (NPSHA) exceeds the net positive suction head required (NPSHR) for the residual head removal (RHR) and contained' spray system (CSS) pumps under worst case ECCS couditions.

Conditions.

1. Physical configuration of piping as per isometric sketch, figure 1, 2.. Both'RHR and botb CSS pumps operating at rated flow (4500 gpm and 4750 gpm respectively),

3. NPSHR for the pumps as per figures 2 and 3,

4. Maximum water temperature 160*F (per FSAR fig 6,2-31),

5. Containment post-LOCA pressure, atmospheric (P = 14.7 psia),

t

6. Containment flooded to elevation 693'0" (technical specification minimum injection volume and ice melt per FSAR figure 6.2-31c.

References. '

1. "Model Study of the Sequoyah RHR Sump," TVA Report No. WM 28-1-45-102, October 1978.

2. " Flow-of Fluids Through Valves,' Fittings, and Pipe," Technical Paper

'No. 410, Crane,.1969.

' Calculations' The NPSH is the total suction head (absolute at the impeller eye) minus the vapor head (absolute) of the liquid being pumped.

NPSH = h a

h vpa

+h st

-h fs (1) where:

h a

=. atmospheric head, absolute pressure (in feet of liquid)

,3 .the surface of the liquid being pumped.

H = vapor head, the head in feet corresponding to the vapor "P" pressure'of liquid at the temperature being pumped.

h =. static. head, static' height in. feet that the liquid

' 'st -

supply level is above theJimpeller eye.

~

h = friction head, allisuction line los'ses (in feet) including fs-all sump screen and form losses, and friction. losses-tthrough pipe, valves, and fittings.

1

+a . ._. _ . _ . _ _. s ._ , ,,w, , ,%,, ,.3 .n y .y,,,e, , , ,w7,,r

)!

Of these, the-atmospheric' head is the product of the containment pressure and the specific-volume. .;

ha= 14.7 x 144(0.01639)'= 34.694 ft.

The vapor head is the product.of the saturation pressure at 160*F and the specific volume.

1 1 h = 4.7414 x 144(0.01639) = 11.191 ft.

vpa

! As defined above, the static head.for the RHR pumps is:

i h = 693' 0" - 655' 7-1/2" = 3/ ' 4-1/2" at i  !

and for the CSS pumps: }

' s h

st

= 693'0"'--656'0"'= 37'0" s

The friction head loss is-the sum of sump screen and form losses and the pipe, valve, and fitting losses. Of these, .the loss through the sump, beginning at, and including the inlet screen and ending at, and including  !

the discharge pipe inlet, may be computed using-l V2 i h =C - '

sump L 2g j - where: Og = the sump loss coefficient as determined in the physical model tests at Norris Engineering Laboratory j (Reference 1) ,

and

, = the velocity head in the discharge pipe given

(

C3 :.0.45 l

h and an 18" sch 10 outlet pipe t

j

then V = flow rate = (18500)(144)(4) = 12.339 ft/sec l area (7.48)(60)(3.1416)(17.5)2 n >

and h = (O'45)(12.339) sump = .06 R.

(2)(32.2) l I

The friction losses for the common piping are greatest in the longer  ;

' length, W to X in figure 1 . Losses in this section computed using reference 2 are:

Straight pipe: 34'.of 18" sch 10-42' of 18" sch 40

-76'. of 18" sch 40 (used for calculations) q

. Fittings: LR 90* elbow (2) L/D ='20 'L = 28(2) = 56' s

LR 50" elbow (1) L/D = 12 L = 18' Tee - run' (1) L/D = 20 L = 28' js

' Total = 120' of 18" sch 40 i

'-2-'

'.l b; '

)

Valve: fully open gate,.L/D'= 13 L = 19' of 18" sch 40

. Water properties: P = 14.7 psia T = 160*F

p. =.60.99 lb/ft 3 u = .41 centipoise Re. = 50.6 Qp = 50.6 (4500 + 4750) 60.99 du 16.876 (0.41) 6

= 4.125 x 10 (fully turbulent) f =-0.0138 2 h

wx = 0.0311 fLQ 5

d

~

= 0.0311 (0.0138) (76 + 102 + 19) (9250)2 16,876

= 5.28.ft.

The friction losses to the RhR pump are greatest in the longest length, B to C in Figure 1. Losses in this section computed using reference 2 l are:

Straight pipe: 36' of 14" sch 40 Fittings: LR 90* elbow (3) L/D = 20 L = 22 (3) = 66' 45* elbow (1) L/D = 16 L = 18' Tee - run (1) L/D = 20' L = 22' i Total = 106' of 14" sch 40 Treat the 18" x 14" reducer as a contraction d

l = 13.124 = 0.78

{ 16.876 K :: 0.15 4D = 12 L = 14' Water properties: P, T, p, u as above Re = 50.6 Q p _ 50.6 (4500) (60.99) du 13.124 (0.41)

= 2.58 x 100 (turbulent) f = 0.0148 2

h = 0.0311 (0.0148) ~(36 + 106 + 14) 4500 BC 5

1.:.124

= 3.73 ft

The friction losses to the CSS pumps are greatest in the longest length, X to Z in Figure 1. Losses in this section computed using reference 2 are:

12" straight pipe: 41' of 12" sch 40 12" fittings: LR 90 elbow (2) L/D = 20 L = 2(20) - 40' Tee - leg (1) L/D = 60 L = 60' 12" x 20" Reducer (expand) K = .4 L/D = 30 L = 30' Total 130' of 12" sch 40 Valve: fully open gate L/D = 13 L = 13' Water properties: P, T, p, u as above Re = 50.6 Qp _ 50.6 (4750) 60.99 du 11.938 (0.41)

Re = 2.99 x 106 (turbulent)

.f = 0.0144 h xzl2,, = 0.0311 (0.0144) (41 + 130 + 13) (4750)2 5

11.938

= 7.67 ft 20" straight pipe: 25' of 20" sch 20-l 20" fittings: LR 90 elbow (2) .L/D = 20 L = 2(32) = 64' 20" x 16" reducer K = 0.12 L/D = 10 L = 16' 20" Tee.- run L/D = 20 L = 32' Total 112' of 20" sch 20 Water properties: P, T, p, u as above l l

Re = 50.6 Qp _ 4750 (60.99) du 19.25 (0.41)

Re = 1.86 x 100 (turbulent) f = 0.0158

.H xz20" = 0.0311 (0.0158) (112 + 25) (4750)2 5

19.25

= 0.58 ft.

h 1

xz =.Hxzl2" + hxz20" = 7.67 + 0.58 = 8.25 ft.

J

-Summary of' friction losses'in feet:

Item RHR Pump CE Pump:

Sump (including screen loss)' 1.06 1.06 l

' Common pipe (W to X) 5.28 5.28 l RHR Suction pipe'(B to C) 3.73 --

CSS Suction Pipe :(X to Z) --

8.25 hj,_ (total) 10.07 14.59 Therefore,-.from (1):

NPSHARHR = H, - h +h st -h, f

= 34.694 - 11.191 + 37.375 - 10.07

= 50.808 ft'.

and NPSHACSS = ah

-h +h se -h fs vpa

= 34.694 - 11.191 + 37.0 - 14.59

= 45.913 ft.

The NPSHR is 19.5 fL. from Figure 2.

RHR and The NPSHR is .0 ft, from Figure 3.

CSS CuntClusion i

The above calculations show that:

i

1. The RfC pumps available suction head exceeds the minimum required by at least.31 ft..

' Excess headRHR = NPSHARHR - NPSHRRHR = 0.808 - 19.5

.= 31.308-ft.

I

2. The CSS pumps available suction' head. exceeds the minimum required  ;

by at least 28 ft. j i

• ' 1 ~

Execss.headRHR = NPSHACSS CSS.  !

E= j 28.913 - f t .'.

I

' j

20"x 12"x 20" ELEVATIONS: '

TEE (TYP)g A,W SUW OUTLET EL 669 '- 8-3/16"

- 20"x 12" C,Y RHR PUW SUCTION EL 655'-7-1/2" ,

RED (TYP) D,Z CONT SPRAY PUW SUCTION EL-656'-0" M \ i DISTANCES:

AB 30' 0F 18" SCH 10 + 38' 0F 18" SCH 40 BC 36' 0F 14" SCH 40 7 BD 67' OF 12" SCH 40 + 21' 0F 20" SCH 20 WX 34' 0F 18" SCH 10 + 42' 0F 18" SCH 40 XY 31' 0F 14" SCH 40 XZ 41' 0F 12" SCH 40 + 25' 0F 20" SCH 20 g

r 18"xl2"xl8" NOTES:

1. ILLUSTR ATIVE ONLY, NOT

?[X TEE (TYP) TO SCALE.

2. ALL BENDS ARE 90 Y {45 ELL 45 ELL 8'xl4" W ECC RED (TYP) 14" STD TEE (TYP)

^

C FIGURE I-SUCTION PIPING FROM ECCS SUMP

q 0-4 4

! 35 -

30 -

/

25 ~

E 20 ~

6

$ 15 -

z O

w

%, 10 -

O W

T 5 -

I I I I I 2000 3000 4000 5000 6000 GPM FIGURE 2- RESIDUAL HEAT REMOVAL PUMP

a e

t a

.35 -

30 -

25 -

20 -

H b

y 15 -

m Z

Q

@ 10 -

=s LO x

5 -

. I t I t g 4000 5000 6000 7000 8000 GPM FIGURE 3- CONTAINMENT SPRAY PUMP

_ _ .