ML20210K450

Joseph M Farley Units 1 & 2 Safety-Related Motor-Operated Valve Differential Pressures for Auxiliary Feedwater Sys

ML20210K450
Person / Time
Site:	Farley
Issue date:	09/30/1986
From:	BECHTEL GROUP, INC.
To:
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ML20210K387	List: ML20210K383 ML20210K417 ML20210K450
References
NUDOCS 8610010436
Download: ML20210K450 (19)

Text

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JOSEPH M. FARLEY UNITS 1 AND 2 SAFETY-RELATED MOV AP's FOR THE

. AUXILIARY FEEDWATER SYSTEM SEPTEMBER, 1986 BECHTEL POWER CORPORATION '

15740 SHADY GROVE ROAD GAITHERSBURG, MD 20877 K $$000y#8 eD

FARLEY AFW MOV AP TABLE OF CONTENTS PAGE I. INTRODUCTION 2-METHODOLOGY 2 II.

A. AUXILIARY FEEDWATER DEFINITION 2 B. GENERAL AFW VALVE SELECTION 3 FLUID SYSTEM EVALUATION 3 C.

D. FARLEY EOP SURVEY 5 E. NORMAL OPERATION 5 APPLICATION TO FARLEY 6 III.

AFW VALVE SELECTION APPLIED TO FARLEY 6 A.

B. FLUID SYSTEM EVALUATION APPLIED TO FARLEY 6 C. LICEN3ING BASES FOR FARLEY 7 8

D. REFERENCES 4 APPENDIX A - EMERGENCY OPERATING PROCEDURES SURVEY - A-1 AUXILIARY FEEDWATER VALVES I

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I. ' INTRODUCTION Provided herein is a detailed review and documentation of the design basis, differential pressures (6P) for the Farley Auxiliary Feedwater (AFW) motor-operated valves. The purpose of this review is to respond in part, to Action Item (a) of I&E Bulletin 85-03.

Specifically, this report provides "the maximum differential pressure during both opening and closing the valve for both normal and abnormal events to the extent that these valve operations and events are included in the existing, approved design basis." This review generally follows the methodology developed as part of the Westinghouse Owners Group Safety Related MOV program, with exceptions / clarifications as noted.

There are two major sections in this report. Section II discusses the methodology used in selecting the AFW MOVs and in evaluating these MOVs to determine the maximum differential pressure. Section III is the application of this methodology to the Farley Huclear Plant. Table 1 lists the AFW.MOVs selected and Table 2 gives the maximum operating APs.

II. METHODOLOGY A. Auxiliary Feedwater System Definition The Auxiliary Feedwater (AFW) System is an engineered sa'fety feature designed to supply feedwater to the steam generators during plant startup, cooldown, and emergency conditions when the normal feedwater supply is not available.

Under emergency conditions, the AFW System provides a redundant means of removing decay and sensible heat from the Reactor Coolant System via the steam generators.

The AFW system is a separate and independent system, and requires no special definition to establish the system boundaries. However, the following explanation is provided for clarity.

In addition to the normal feedwater source from the condensate storage tank, a redundant backup source is provided from the safety class 2B portion of the Service Water System. Under emergency conditions, AFW is defined as:

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1. Those portions of the system required to supply steam to the turbine driven pump.

2. Those portions of the system taking suction from the Condensate Storage Tank and providing discharge, via the two motor driven or one steam turbine driven pumps, to individual lines feeding each steam generator.

3. Those portions of the system which, alt'ernatively, take suction from the safety related portion of the Service Water System.

The AFW System is further described in FSAR Section 6.5.

B. General AFW System Valve Selection All MOVs within the AFW system are included in the list of valves to be examined for maximum differential pressure. Under evaluated conditions, these valves function toj B.1 Establish a flowpath(a) from the AFW safety grade water source (or; its backup) to the steam generators, and to isolate AFW flow from the motor driven pumps to the faulted steam generator.

B.2 Establish an AFW flowpath(s) from the AFW sources to the steam generators and to prevent backflow to the AFW System.

B.3 Establish a steam delivery flowpath to the AFW turbine and to trip the turbine at turbine overspeed.

MOV valve selection for the AFW System is summarized in Table 1.

C. Fluid System Evaluation The fluid. system evaluation determined the maximum operating open/close Aps for the selected MOVs based on system configuration, equipment capability, and design operating modes. The assumptions applicable to these Ap determinations were based on the methodology provided in the Westinghouse Owners Group (WOG) Safety-Related MOV Program Final Report (March 1986; Reference 1) with 3

exceptions as noted in Section III.B. The results of the evaluation based on this methodology are summarized in Table 2.

The AFW provides a reliable source of feedwater to the steam generators in the event main feedwater is either lost or isolated.

Two different sets of single failure criteria were used for the fluid system evaluation depending on whether short term operating modes or long term operating modes are being considered.

1. Short-Term Operation - Single active failures were considered. Passive failures were not assumed. This means that gross check valve backleakage was not assumed (requires a passive failure of the check valve).

2. Long-Term Operation - Both active and passive failures were considered credible. However, the analysis was based on a single failure which was found to be the worse of either the active or passive failures.

In general, the fluid system evaluation was the determination of a maximum operating Ap for any system operating mode and design basis event.

As noted in Section III.B, calculating the maximum operating AP by neglecting piping pressure losses or by basing it on the pump head at minimum flow does not necessarily represent realistic operating conditions.

For this evaluation, the following equipment and system configuration information was considered in the determination of the maximum operating Ap provided in Table 2:

1. Pumps Operating /not operating, operation configuration (miniflow/no miniflow, maximum discharge head).

2. Relief Valves Setpoint limits system pressure.

3. Piping Line losses and elevation.

changes

4. Check Valves No gross backleakage.

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5. Tanks Elevation head and design pressure.

.6. Other MOVs Position (open/close).

Outside the AFW system, steam generator pressure was considered for determination of AP.

Based on the above, maximum operating MOV~

differential pressures were developed for both open and close operations. For each

. maximum operating Ap, a' justification is given based on system configuration and equipment constraints.

Finally, these maximum operating differential pressures were compared against the valve design specification Ap to verify adequate design.

D. Farley EOP Survey The Farley EOP Survey determined when the selected AFW MOVs (See Table 1) are required to function for emergency operation. In addition, the survey identified other important characteristics of the system operation which impact the MOV's capability to function. (Details the EOP survey are provided in Appendix A.)

Many of the steps on this list were repetitive.

Therefore, the list was consolidated to.a few general cases for each valve. Each general case gives the EOP operation and the required MOV operation ~(open or close) during the EOP operation.

The EOP operation general cases were checked against the fluid system assumptions. If the EOPs and the fluid system assumptions were consistent, then a "yes" appears in the "EOP confirmation" column of Table 2.

E. Normal Operation  ;

The AFW system generally functions during off-normal situations when auxiliary feedwater is 5

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needed (i.e., mainfeed is lost-or tripped).

A part of the system has normal operative functions during start-up, shutdown and hot stand by conditions. However, all of these normal AFW system operations are bounded by off-normal, accident scenarios.

III. APPLICATION TO FARLEY A. AFW System Valve Selection Applied to Farley Using the selection criteria defined in II.B., the AFW system valve list was generated for Farley, and is shown in Table 1. The. table' lists the MOVs by function and by Farley MOV number. In addition, valve position information and which functional selection criteria the valve meets to be included on the list (either B.1, B.2, B.3, as defined in the " General AFW System Valve Selection"Section II.B) is given.

B. Fluid System Evaluation Applied to Farley The application of the fluid system. evaluation to the AFW system is shown in Table 2. The table gives the following information:

1. Valve Description

2. Farley MOV Number

3. Design (Spec.) AP

4. Maximum Operating AP (Based upon the approach described in Section II)

5. Justification for Maximum Operating AP

6. EOP Confirmation of Operating Assumptions Following Table 2 is a summe.ry of the applicable justifications.

The maximum operating differential pressures for valves MOV-3764 A through F, MOV-3350 A through C, MOV-3209 A and B, MOV-3210 A and B, and MOV-3216 are not based completely on the assumptions used in Reference 1. The following discussion is provided as a justification for not determining the maximum operating AP for these valves based on pump miniflow discharge head as suggested in Reference

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Valves MOV-3764 A through F and MOV-3350 A through C are normally open and fail "as is". In the event of a feedwater line break, these valves will be 6

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remotely actuated to isolate flow from the motor-driven pump to the faulted steam generators.

During emergency conditions (e.g., a line break in any one of the feedwater lines), the FSAR states that a minimum flow of 350 gpm following a reactor trip be maintained to the remaining two intact steam generators. The Emergency Operating Procedures incorporate this flow requirement. The MOV's in the broken line which are required to be closed for isolation will see a maximum differential pressure of 1270 psi, the pump discharge head at rated flow; line losses will actually reduce this pressure. The WOG report, Reference 1, suggests using the supply pump discharge head at mimimum flow which was assumed to be the pump head at a mimimum flow of 50 gpm and results in valve AP's of 1525 psid. However, the discharge head at rated flow (i.e., 1270 psid) is considered more appropriate.

Valves-MOV-3209 A and B, MOV-3210 A and B, and MOV-3216 are located in the lines providing emergency, backup service water to the auxiliary The pump head corresponding to feedwater pumps.

the flow required from the service water system is equivalent to about 100 psig. With the normal losses in the pipe and fittings, the differential

! pressure which these valves would see is not expected to exceed 100 psig. Reference 1 suggests using the pump maximum head at minimum flow which was assumed to be the pump head at 10% of rated flow and results in valve AP's of 145 psid.

However, the pump discharge head, less line losses, at normal Service Water System flow (prior to LOCA injection (i.e., 100 psid)) is considered more

! appropriate.

C. Licensing Bases for Farley Chapters 6 and 15 of the Farley FSAR were reviewed to identify any licensing commitments pertinent to the MOV effort. Specifically, the objective of the FSAR review was to identify the actuation requirements for the MOV's included in the study to establish required flow paths for the auxiliary feedwater.

The normal positions for the AFW motor operated valves are summarized, and the appropriate section of the FSAR which governs the actuation of each valve is referenced in Table 1 of this report.

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D. References

1. Westinghouse Owners Group Safety-Related MOV Program Final Report (March 1986).

2. Farley Units 1 and 2 FSAR.

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' 'b TABLE 1 Farley Units 1 & 2 Design Bases for Operation of AFW System MOV's VALVE POSITION OR MOV NUMBER REPOSITION FUNCTION

• Motor-Driven MOV-3764A Normally Open, B.1 Pump Discharge MOV-3764B Remotely Closed Isolation MOV-3764C from Control Valves MOV-3764D Room - Ref.

MOV-3764E FSAR Section MOV-3764F 6.5.3 AFW Discharge MOV-3350A Normally Open (with B.2 Isolation MOV-3350B power' racked out),

Stop Check MOV-3350C Remotely closed Valves from Control Room - Ref.

FSAR Section 6.5.2 and Table 6.2-32 Suction.from MOV-3209A Normally Closed, B.1 Essential MOV-3209B Remote manually Service Water MOV-3210A Opened - Ref.

MOV-3210B FSAR Section MOV-3216 6.5.2 Mechanical MOV-3406 Normally Open - B.3 Trip & Throttle Ref. FSAR Valve (Steam Section 6.5.2 Supply to Turbine Driven Pump)

• See Section II.B (General AFW System Valve Selection) for an explanation of " function".

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' TABLE 2 -

FARLEY UNITS 1 & 2 AUXILIARY FEEDWATER SYSTEM DATA

SUMMARY

EOP DESIGN MAXIMUM JUSTIFICATION CONFIRMATION

! FOR MAX OF OPERATING

' VALVE (SPEC) AP OPERATING AP CLOSE OPEN CLOSE OPEN OPERATING AP ASSUMPTIONS MOV NUMBER

(PSID) (PSID) (See Note 2) 1270 1270 1270 1270 Open Yes Motor-Driven MOV-3764A Pump Discharge MOV-3764B (See Note 1)

MOV-3764C Close Isolation Valves MOV-3764D (See Note 1)

MOV-3764E

'5 MOV-3764F 1600 1600 1270 1270 Open Yes AFW Discharge MOV-3350A Isolation MOV-3350B (See Note 1)

MOV-3350C Close Stop Check Valves (See Note 1) 100 100 100 100 Open Yes Suction Frcm MOV-3209A Essential MOV-3209B (See Note 3)

MOV-3210A Close Service Water i

MOV-3210B (See Note 3)

MOV-3216 1250 1250 1110 1110 Open Yes Mech. Trip MOV-3406

& Throttle (See Note 4) l Close Valve (Steam (See Note 4)

Supply to Turbine-driven i Pump) e 4

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JUSTIFICATION FOR TABLE 2 NOTES: 1. Maximum operating AP was calculated based on emergency operating flow requirements rather than AFW pump miniflow discharge head - See Section III.B for justification.

2. Atmospheric pressure is postulated for down stream condition.

3. Maximum operating AP was calculated based on emergency operating flow requirements rather than service water pump miniflow discharge head-

- See Section III.B for justification.

4. This valve must be able to open and close against steam' pressure equal to the lowest safety valve setpoint plus 3% accumulation.

A heavy spring in the yoke closes the valve when tripped.

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t JOSEPH M. FARLEY UNITS 1 AND 2 EMERGENCY OPERATING PROCEDURES 4

SURVEY AUXILIARY FEEDWATER VALVES APPENDIX A I

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Turbine Trip and Throttle Valve (MOV-3406)

Case 1: Establish a steam delivery flowpath - open valve ECP - 0.0 Step 4.2 FRP - H.1 Step 3.1.1 FRP - H.S Step 4.2.1 Case 1: Open valve against steam pressure equal to the lowest safety valve setpoint + 3%

accumulation.

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MDAFW Pump Discharge Isolation Valves (MOV-3764 A, B, C, D, E, and F)

Case 1: Establish AFW flowpath - Open valves FRP - H.1 Step 3.2 FRP - H.1 Step 17 FRP - H.3 Step 4.3 FRP - H.5 Step 4.3 FRP - S.1 Step 6.3 Case 2: Isolate AFW flowpath .close valves EEP - 2 Step 5.1 EEP - 3 Step 6.1 FRP - H.2 Step 6.1 FRP - H.3 Step 3.1 FRP - H.5 Step 3.1.1

FRP - P.1 Step 1.3 FRP - P.2 Step 1.3 l FRP - S.1 Step 8.2 FRP - Z.1 Step 6.1 Case 1: Open valves with pumps running case 2: Close valves with pumps running 4

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AFW Discharge Isolation Stop Valves (MOV-3350A, B and C)

Case 1

Establish AFW flowpath - open valves FRP - H.1 Step 3.2 i

FRP - H.1 Step 17 i FRP - H.3 Step 4.3 i FRP - H.5 Step 4.3 j FRP - S.1 Step 6.3

case 1

Open valves with auxiliary feedwater pumps running i

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i Suction from Essential Service Water (MOV-3209A and B; 3210A and B; and 3216)

Case 1: Establish AFW flowpath from backup water source - open valves ESP - 0.2 Step 9 EEP - 0 Step 4.1, Foldout Page EEP - 0 Step 19.2 EEP - 1 Step 4.2, Foldout Page EEP - 1 Step 3 EEP - 2 Step 6 EEP'- 3 Step 4.2', Foldout Page EEP - 3 Step 7 ESP - 0.0 Step 4.1, Foldout Page ESP - 0.1 Step 5.2 ESP - 0.1 Step 4.1, Foldout Page ESP - 0.2 Step 4.1, Foldout Page ESP - 0.4 Step 4.1, Foldout Page ESP - 1.1 Step 14 ESP - 1.1 Step 4.2, Foldout Page ESP - 1.2 Step 4 ESP - 1.2 Step 4.2, Foldout Page ESP - 1.3 Step 4.2, Foldout Page ESP - 1.4 Step 4.2, Foldout Page ESP - 3.1 Step 4.2, Foldout Page ESP - 3.1 Step 5 ESP - 3.2 Step 5 ESP - 3.2 Step 4.2, Foldout Page ESP - 3.3 Step 5 ESP - 3.3 Step 4.2 Foldout Page ECP - 0.0 Step 11.6 ECP - 0.1 Step 7 ECF - 0.2 Step 6 ECP - 2.1 Step 1.3 ECP - 2.1 Step 4.2, Foldout Page ECP - 3.1 Step 6 ECP - 3.1 Step 4.2, Foldout Page ECP - 3.2 Step 4 ECP - 3.2 Step 4.2, Foldout Page ECP - 3.3 Step 6 ECP - 3.3 Step 4.2, Foldout Page FRP - C.1 Step 7 FRP - C.2 Step 7 FRP - H.1 Step 3.1 FRP - H.5 Step 4.4.1 Case 1: Open valves against essential service water source A-5

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