ML20141G703

Revision B to Required Submergence to Prevent Vortexing in Csp

ML20141G703
Person / Time
Site:	Waterford
Issue date:	07/05/1997
From:	Pellerin S, Viener D, Weicks R ENTERGY OPERATIONS, INC.
To:
Shared Package
ML20141G700	List: ML20141G695 ML20141G703 ML20141G708 ML20141G713
References
EC-M97-025, EC-M97-025-RB, EC-M97-25, EC-M97-25-RB, NUDOCS 9707100193
Download: ML20141G703 (9)

Text

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ENGINEERING CALCULATION COVER SHEET ENTERGY l

l 813.18 (Original R-Type or R-Type from Attachment Vil)  ;

CALCULATION NO. EC-M97-025 REV. NO. B

TITLE Required Submergence to Prevent Vortexing in the CSP SUBJECT Required Submergence to Prevent Vortexing in the CSP i

AFFECTED SYSTEMS EFW.CMU THIS CALCULATION SUPERSEDES N/A COMPUTER SOFTWARE USED MS Excel 5.0 CODE VERSION DISK CALCULATION CLASSIFICATION:

O Non-Quality Related @ Safety Related O Quality Related: Important to Safety CALCULATION PERFORMED UNDER:

@ Waterford 3 Procedures O Supplier Approved Quality Procedures CALCULATION STATUS:

O Final - List Pending Calculation (s) and/or Calculation Changes Incorporated O Void O Superseded - New Calc. No.

@ Pending (Not Currently Installed) '

O Partially Installed / implemented initial Date O Completely Installed / Implemented initial Date O Canceled initial Date O Study - Does Not Represent, And Can Not Be Used For The Design Basis of The Plant Prepared By: Ron Weicks h ENGl Date: 7[f[Q7 Verified / Reviewed By: steve pelle ' - Date: 7' hi7 Approved By: David viener Date: .7 /

SUPdRVISOR l/ /

NOECP-011 Rev. 3 9707100193 970707 Form 1, Rev. 2 ADOCK 050003 2

%DR

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TABLE OF CONTENTS l

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1.0 Purpose ......... ... . . . . . . . . . . . . . . . . . . . . .

........................................1 2.0 Conclusion.. .... . .... . . .... . .. . . ... . ..... ..........................1 3.0 References . . . . . . . . . . . . . . . . . . . . .. . . . . . . . ......................2 i 4.0 input Criteria.. . . . . . . . . . .. .. .

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t 5.0 Assumptions . .... . ... .... .. ... .. ...... ... .. ..... ... .....................3 i l

6.0 Method of Analysis . ... . . . . . . . .. . . ... ..................................4  ;

i 7.0 Calculation Computation . . .. .. ...................,.................................5~

8. 0 R e s u l t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Attachment 8.1 - Report on Vortexing in the Condensate Storage Pool ,

Attachment 8.2 - Calculation Checklist i 1

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RECORD OF REVISION l REVISION CHANGE DESCRIPTION OF EFFECTIVE PAGES l NUMBER REVISION / CHANGE DATE AFFECTED l A initial issue 7/1/97 ALL i

i B Revision to increase scaled flow to include 7/4/97 ALL minimum recirculation flow in total discharge from CSP for scaled testing.

Changes were also made to the EFW flow calculation to account for heat from two  ;

RCPS and to reduce maximum CSP  ;

temperature to 100 F.  :

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I 1.0 PURPOSE The purpose of this calculation is to determine minimum liquid level required in the

• Condensate Storage Pool (CSP) to prevent air ingestion, due to vortexing during .

Emergency Feedwater (EFW) pump operation. This calculation establishes inputs

, for scale testing which was performed to empirically determine the minimum liquid ,

level required in the CSP.

I The test report for vortexing in the CSP is included as Attachment 8.1, with the test results documented in Section 2.0.

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2.0 CONCLUSION

Based on Attachment 8.1, the minimum liquid level and corresponding liquid level percentage to prevent vortexing is provided in the following table. All liquid levels

] are referenced from the 0% indicator level (4).

i Storage Tank Minimum Minimum Liquid Level Liquid Level % [4]

Condensate Storage Pool 9.0 inches 3.57 %

The minimum required level in the Condensate Storage Pool to prevent vortexing into the Emergency Feedwater Pumps is 3.57%. The remaining water volume,

below the 3.57% level, should not be considered for uninterrupted flow into' the steam generators. These results are based on scaled testing with a cruciform vortex breaker installed inside the screen above the suction nozzles.

Operation of the CCW make-up pumps is intermittent and is not expected to exceed the EFW flowrate calculated in Section 7.0. Therefore, the minimum liquid level in the CSP for operation of the CCW make-up pumps is bounded by the

. results above.

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3.0 REFERENCES

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1. Waterford 3 SES Condition Report 95-0657

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2. Crane Technical Paper 410, Flow of Fluids Through Valves, Fittings & Pipe .

3. Waterford 3 Emergency Operating Procedures:

OP-902-006, Loss of Feedwater OP-902-007, Steam Generator Tube Rupture i OP-902-008, Safety Function Recovery Procedure OP-902-002, Loss of Coolant Accident  !

OP-902-004, Excess Steam Demand l OP-902-ATT, Emergency Operating Procedure Attachments  !

4. Waterford 3 Engineering Calc. EC-M84-001 Rev. 6, Tank Volume vs. Level

5. Waterford 3 DBD-003 Rev.1, Emergency Feedwater System j

6. Waterford 3 SES Isometric Diagram 4305-6636 Rev. 9

7. Waterford 3 SES isometric Diagram 4305-6634 Rev. 8

8. Waterford 3 SES Station Information Management System

9. Waterford 3 Engineering Calc. EC-M97-006 Rev. A, Design Basis for CCW Makeup.

10. Waterford 3 Letter PSA-89-255, Decay Heat Power Curves 1979 and 1973 ANS Standard

11. Waterford 3 Engineering Calc. EC-S96-005 Rev. A, Cycle 10 Power Uprate Safety Analysis Groundrules

12. ASME Steam Tables Fifth Edition

13. Waterford 3 Engineering cale. EC-S89-003 Rev.1, EFW Requirements

14. Waterford 3 SES Drawing 1564-G907 Rev. 9.

15. Ebasco Specification 1564.119 Rev. 9, Essential Cooling Water System Pumps.

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4.0 INPUT CRITERIA The methodology of calculation EC-S89-003 [13] is interpreted to determine the ,

required flowrate into the steam generators at the time the Condensate Storage  ;

Pool is nearing a low level. The required flowrate, calculated in Section 7.0, is the i

! rate at wnich water is pumped into the steam generator to maintain steam i l generator level. The pump capabilities are provided in the Design Basis l Document [5].

i Vessel dimensions are located on the referenced tank drawings and engineering i calculations. The source for these inputs is referenced within the calculation. i f

5.0 ASSUMPTIONS

1. It is conservatively assumed that air ingestion to the pumps can occur at the onset of a Type 2 vortex. Although, by definition, no air ingestion occurs during a Type 2 vortex, it is acknowledged that vortex type is unpredictable.

2. The minimum recirculation flow with all three EFW pumps operating is 170 ,

gpm with an inlet 7.5 feet from the nearest EFW suction nozzle [5,14). The minimum recirculation flow for the CCW makeup pump is 30 gpm with an inlet 20.5 feet from the nearest EFW suction nozzle [5,14). Therefore, the scaling factor for modeling the CSP is based on 170 gpm minimum recirculation from ,

all three of the EFW pumps. The effect of minimum recirculation from CCW '

makeup is assumed to be negligible due to the lower flowrate (30 gpm vs.170 gpm) and the proximity to the nearest EFW suction nozzle (20.5 ft. vs. 7.5 ft.),

3. The CSP has three 6" outlet nozzles at the bottom of the pool. Two of the <

nozzles are connected to the suction of the Emergency Feedwater Pumps and the third nozzle is connected to the suction of the CCW makeup pumps [14). ,

Per section 7 of this calculation, EFW flow to the steam generators at the time i of low CSP levels is 304 gpm. Adding 170 gpm for minimum recirculation, total flow for EFW operation is 474 gpm. The CCW makeup pumps operate in minimum recirculation mode (30 gpm) and provide make-up only on an intermittent basis to the EDG Jacket Water Standpipes (11.7 gallons), Chilled Water Expansion Tanks (70.3 gallons), and CCW Surge Tank (44.12 gallons)

[9,15). Based on the short time period that CCW makeup is required, it is assumed that the most limiting case for vortex formation in the CSP occurs from continuous EFW pump operation.

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The CSP consists of two nozzles which lead to a common suction hea ,

the EFW pumps. For conservatism, all EFW flow is assumed to pass through one EFW nozzle. Although this is non-mechanistic, this assumption provides a defined conservatism for minimum submergence requirements.

5. Makeup to the CSP is not assumed to occur.

6.

The time at which the decay heat load is taken is based upon the Typical i

Feedwater Capacity versus Time Remaining Until Shutdown Cooling Required curve [3). The initial water available in the CSP for EFW is 170,000 gallons, and the estimated upper bound CSP level for vortexing is 10% or 21,063 gallons {4). Therefore, the Feedwater Capacity to use on the curve is approximately 149,000 gallons. The corresponding Time Remaining Until Shutdown Cooling Required is 9.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. This calculation will conservatively assume 4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

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Based on the Cycle 10 Power Uprate Safety Analysis Groundrules, full thermal power is conservatively assumed to be 3661 MW.

8.

A CSP temperature of 100 F is conservatively assumed [11).

9. Per reference 3, two RCPs will be tripped for the limiting accidents which require EFW, therefore, the heat input by operation of two RCPs is assumed in the required flow calculation for EFW.

6.0 METHOD OF ANALYSIS The minimum level required in the CSP to prevent vortexing is determined empirically using a scaled model. Several tests were performed utilizing various l

vortex breaker designs and the empirical data was compared to correlations  !

reported by G. Hecker of Alden Research Laboratories to select the final vortex breaker design.

The flowrate from the CSP is required to perform the scaled testing. The following

! analysis uses standard engineering conversions to datermine the fluid flowrate and velocity into suction piping.

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Definition of Variables l .

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i .v = Specific volume (ft*lb)

=

0.01613 ft*Ib at 100 F [12]

d =

Drain diameter (ft)

! = 6.065 in. [2,6,7]

= 0.5054 ft.

Ah =

Enthalpy difference between CSP and SG steam (Btu /lb)

O = Volumetric Flowrate (GPM) q = Decay heat load (Btu / min)

=

Vo Drain velocity (ft/sec) 7.0 CALCULATION COMPUTATION 4

The required flowrate from the Condensate Storage Pool, CMUMPOL0001, into the Emergency Feedwater (EFW) Pump suction piping is calculated based on the decay heat load at the time the CSP is near empty and the heat load from ,

operating two Reactor Coolant Pumps (RCPs).

At 4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post-accident, the upper bound decay heat load is 0.010454% of full thermal power [10]. Full thermal power is 3661 MW, and the heat input by j

operation of two RCPs is 11.4 MW [11]. The total heat load at 4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post '

accident, in Btu / min, is calculated as follows.

q= I1.4 +(3661)(0.010454)'(3,413,000)

= 2,825,514 Bru 1

The volumetric Emergency Feedwater flowrate to maintain steam generator level is calculated by dividing the heat load by the change in enthalpy between the CSP water and saturated steam in the steam generator. Using a CSP temperature of  :

100 F [11), gives an initial enthalpy of 68 Btu /lb [12]. At the lowest set main steam safety valve set pressure, including As-found tolerance, of 1116.7 psia (1102 psig

+14.7) [8], the saturated liquid enthalpy is 559.9 Btu /lb, and the latent heat of vaporization is 628.5 Btu /lb [12]. Therefore, the EFW flowrate can be calculated as follows:

G =AhM(7.48052) = .

(0.01613)(7.48052) = 304 gpm

-(559.9 - 68) + 628.5 l

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i The Emergency Feedwater Pump suction piping connects to the CSP via two 6.065 in (0.5054 ft.) diameter suction nozzles (6,7]. For conservatism, flow is assumed through only one nozzle to calculate the drain velocity:

304 + 170 V=

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= 5.26f Vsec x(7.48052)(60)(0.253),

The flowrate and drain velocity are used as inputs for scaled testing on the CSP to determine the height at which vortexing occurs. The assumption that all flow passes through one nozzle is a defined conservatism for use in the testing.

8.0 RESULTS The scale testing of the CSP determined: j

1. The vortex breaker design - cruciform under suction screen.

2. Confirmation of minimum level, or submergence required to prevent vortexing with a cruciform vortex breaker - 9.0" i

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