ML20235J650
| ML20235J650 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/30/1987 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20235J640 | List: |
| References | |
| WR28-2-45-130, NUDOCS 8707150677 | |
| Download: ML20235J650 (17) | |
Text
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Tennessee Valley Authority Office of' Natural Resources and Economic Development Division of Air and Water Resources Engineering Laboratory 2
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fiYDRAULIC PERFORMANCE OF THE SEOUOYAH RHR SUMP AT REDUCED DISCHARGE AND WATER LEVEL e
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Report No. WR28-2-45-130
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Prepared by Theodoric G. Fain Norris, Tennessee April 1987 8707150677 870708 PDR ADOCK 05000327 s
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INTRODUCTION e
l Vortexing propensity of the containment sump for Sequoyah f Nuclear Plant was evaluated by the Engineering Laboratory using' a 1:4 f
scale physical model (Fain, 1978).
For reference, the original sump
'3 design and the f-inal design resulting from the model study are shown in 1
, Figures 1 and 2,
respectively.
The scale used to describe vortex strength is presented in Figure 3.
The sump was provided with two identical discharge pipes, as shown in Figure 1.
Each pipe had a pump
}llQ runout flowrate of 9,875 gal / min.
The water depth measured from the
- d containment floor (El 679.78) was 13.2 feet, as shown in Figure 2.
An accident condition postulated af ter completion of the model 4
study (Wilson, 1987) could require operation of the sump at a reduced water depth (3.2 feet) concurrent with a reduced total flowrate (13,000 gal / min).
At the request of the Project Engineer, Sequoyah Engineering Project (Wilson,1987), analysis was made of the vortexing propensity of the sump using the postulated operating conditions.
This report presents results and conclusions of the requested analysis.
The analysis was based on records of tests performed during the model study and -on subsequent research published by others.
Additionally, reference is made to a similar analysis. (Fain,1987) which evaluated vortexing propensity at reduced water levels, but with design flowrates.
l
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-M.'
..e DISCUSSION E
3 4
Scale Effects validity of the Sequoyah model test data at the given water i
depth, S, and flowrate, Q, was verified by comparing model values of the Froude number, pipe Reynolds number, radial Reynolds number, and Weber number with values used in an NRC-sponsored parametric test (Weigand, et al.,1982), and with other published values.
These comparisons are shown in Figures 4,
5, 6,
and 7, respectively.
Within the ranges of values used in the NRC test, a 1:4 scale model tested at Alden Research a
l m_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
2 Laboratory was found to accurately predict the hydraulic performance of its prototype.
Oth'e r research indicates that model predictions are accurate if the pipe Reynolds number, radial Reynolds number, and Weber number are larger than the minimum values used in the NRC test j (Padmanabhan and Hecker,1984).
As can be seen in Figures 4 through 7, N] the Sequoyah model values at the given S and Q meet those criteria.
Thus, vortexing propensity predicted by the Sequoyah model for the 4.a postulated operating condition should be. reliable.
i, f2 Model Tests and Test Results
'4 Test data for the final design at reduced water depths and j
were not available.
Consequently, vortexing propensity was
{ flowrates determined from data for the original design, as discussed in the previous report (Fain, 1987).
Figure 8 displays maximum observed vortex strength as functions of water depth and flowrate.
The data were recorded during drawdown tests of the original design with no sump screen blockage.
Test log h
notes on the series indicated that in all cases no air-drawing vortices s
were observed until the water surf ace reached the elevation of the sump cover.
The data in Figure 8 illustrates that vortex strength does not change significantly between the 8-foot and 3.2-foot water depths.
- Also, vortex strength decreases noticeably with decreasing flowrate.
These two j
trends would prevail with screen blockage, which is the worst case 3
condition.
Figure 9 displays maximum observed vortex strength as a function I
of flowrate for both blocked and unblocked sump cover screens.
The data were recorded during tests at an 8-foot water depth with various flowrates.
Curves enveloping th.e data are included to aid in visualization.
This graph, along with Figure 8, indicates that with 50 percent blocked screens, a 3.2-f oot water depth, and a 13,000 gal / min total flowrate, a maximum vortex of about Strength 3 would occur.
The minimum water depth at which no air would be ingested (ie., maximum vortices about Strength 4) is conservatively 2.5 feet.
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Other Considerations
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4 Figure 10 presents a plot of submergence depth..versus Froude number for 66. existing or modeled hydraulic intakes (Gulliver, et al.,
1986).
Intakes with and without vortex problems are idertified,. and a recommended region for horizontal intakes is delineated.
As can be seen, the Sequoyah sump at the postulated water depth and flowrate is within the recommended region and should therefore have no significant vortexing problems.
The probable ef fect of an air-drawing vortex (if, contrary to expectation, one should occur) was also considered.
Measured levels of air ingestion with freestanding air-core vortices are generally less than one percent of the water volume (Padmanabhan and Hecker,1982).
On the other hand, perf ormances of both axial-flow and radial-flow pumps are not noticeably reduced by quantities of ingested air less than three percent (Murakami and Minemura, 1978).
These conclusions were also included in a subsequent NRC report (Kamath, et al., 1982).
No correlation was found between surface vortices and sump loss coefficients, which affect discharge capacity and net positive suction head (Weigand, et al.,
1982).
Therefore, the presence of even an intermittent Strength 6 vortex at Sequoyah should not significantly reduce the sump performance.
CONCLUSIONS I
If no modifications are made in the geometry at the plant which would af fett the sunp aprroach flow and the sump is operated at water depths and flowrates of approximately 3.2 feet and 13,000 gal / min, respective 1v. ',cermittent surface vortices of about Strength 3 would probably appear.
At a 2.5-foot water depth, vortices of about Strength 4 would probably appear.
The presence of these vortices would not adversely af f ect the hydraulic performance of the sump.
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REFERENCES l
Fain, T.
G.,
O'ctober 1978, "Model Study of the Sequoyah RHR Sump," TVA l
Report No. WM28-1-45-102.
1
- Fain, T.
G.,
March 1987, "Vortexing Propensity of the RHR Sump at Sequoyah Nuclear Plant," TVA Report No. WR28-3-45-127.
- Gulliver, J.
S.,
A.
J.
Rindels, and K.
C.
Lindblom, September 1986,
" Designing Intakes to Avoid Free-Surf ace Vortices," Water Power and Dam Construction.
- Kamath, P.
S.,
T.
G.
Tantillo, and W.
L.
Swift, September 1982, "An Assessment of Residual Heat Removal and Containment Spray Pump Performance Under Air and Debris Ingesting Conditions,"
U.S.
Nuclear Regulatory Commission, Report No. NUREG/CR-2792.
- Murakami, M.
and K.
Minemura, 1978, "Ef f acts of Entrained Air on the Performance of a Horizontal Axial-Flow Pump," Symposium on Polyphase Flow in Turbomachinery, ASME Winter Annual Meeting, San Francisco, CA.
Padmarabhan, M. and G. E. Hecker,1982, " Assessment of Scale Ef fects on Vortexing, Swirl, and Inlet Losses in large Scale Sump Models,"
U.S.
Nuclear Regulatory Commission, Report No. NUREG/CR-2760.
Padmanabhan, M. and G. E. Hecker, November 1984, " Scale Effects in Pump Sump Models," Journal of Hydraulic Engineering, Vol. 110, No. 11.
Weigand, G.
G., M. S. Krein, M. J. Wesf er, and M. Padmanabhan, July 1982, "A
Parametric Study of Containment Emergency Sump Performance,"
U.S.
Nuclear Regulatory Commission, Report No. NUREG/CR-2758.
- Wilson, D.
W.,
January 1987, Memorandum to E.
E.
- Driver, Chief, Engineering Laboratory,
Subject:
"Sequoyah Nuclear Plant (SON)
Containment Sump Vortexing," No. 825-871027-010.
(Augmented by notes of conversation with Rob McKeehan and Ed Sheehy).
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4" SECTION A'- A Figure 1 : Original Containment Sump Design 4Ungs I and 2 Identical)
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GRATING ON SICES AND REAR WALL CF SUMP (NOT TO SCALE)
Figure 2:
Final Design with '/ortex Suppressors anc Other Maci fications
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Figure 3:
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SUMP SUBMERGENCE DEPTH, FT.
Figure 4: Modei Froude Number
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8 SUMP SUBMERGENCE DEPTH, FT.
Figure 5: Model Pipe ~ Reynolds Number I
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SUMP SUBMERGENCE DEPTH, FT.
Figure 6: Model Radial Reynolds Number e
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8 SUMP SUBMERGENCE DEPTH, FT Figure 7: Model Weber Number G
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NOTES 13 4
Original sump design with l-12 no vortex suppression devices in place and no l
screen blockage H
11 WWu.
to g
O Tests at high discharge O
Oa g'
9 Tests at design discharge u.
O O
'O O
O Discharge varies z
Q 9,750-25,000 gpm per Z
pipe. (Design O = 9,87 5 O
7 O p m / pip e ).
H z
(
O O
6 O
g 0
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5 H
n-O w
0 Q
e4 a:
C O
, POSTULATED W ATER LEVEL W
f 3
a
_ SUMP COVER 2
1 TR ASH CURS j
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CONTAINMENT FLOOR 0
0 1
2 3
4 5
6 j
M AXIMUM VORTEX STRENGTH f
(see Figure 3) l Figure 8: Effects of Water Depth and Discharge on Vortex Strength Tests
I 13 1
l 55.0 b
50.0 E
C-45.0
?
o Y
7 2X Design C
'o 40.0 l
M NOTES:
d 35.0
?
@ Original design with unblocked screens.
30.0
?
g c
5 9 Original design with fifty 5
percent block 6td screens.
25.0 e
y g
W ater level = 8 f eet o
g L
}
J n0.0 -
3
=
l l
i Design Q = 13750 gpm J
15.0 W
e H
O F-10.0
/
5.0@
0 1
2 3
4 5
6 VORTEX STRENGTH (See Figure 3)
Figure 9: Effect of Sumo Discharge on Vortex Strength at 8-f oot Submergence
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Postulated Sequoyah F Operating Point I
e E-2
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e 3
3 O
I e
O l
o o
O CD 0 horizontal intake 1
O vertical intake
.g (b
G B intakes with vortex problems O O intakes with no problems O
0 0
1 2
a y
Fr =
Vg D Figure 10. Dimensionless Plot of Data Obtained from Intaket, at Existing Installations and Model Studies of Proposed Installations.
(
Reference:
Gulliver, e t al.,1986)
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1 l'
ENCLOSURE 4 l
SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 LIST OF COMMITMENTS ASSOCIATED WITH RESOLUTION OF SPRAY WATER LEAKAGE BEHIND THE CRANE WAL,. ISSUE
Y-
/
]
a ENCLOSURE 4 SEQUOYAH NUCLEAR PLANT (SQW) UNITS 1 AND 2 SPRAY WATER LEAKAGE BEHIND THE CRANE WALL ISSUE FSAR AMENDMENT COMMITMENTS
)
ACTIVITY COMMITMENT DATE
' Amend FSAR text to reflect addition of April 15, 1988 curbs on operating deck and drains and curbs in accumulator rooms
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