ML20195J539

Forwards Results of Evaluations on safety-related Pumps & Justification for Continued Operation,Per NRC Bulletin 88-004, Potential Safety-Related Pump Loss. Final Evaluation Will Not Be Completed Until Early 1989

ML20195J539
Person / Time
Site:	Farley
Issue date:	11/30/1988
From:	Hairston W ALABAMA POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
IEB-88-004, IEB-88-4, NUDOCS 8812020241
Download: ML20195J539 (9)

Text

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, $4 tuna Pow;r Cornpany 600 North 18th Street Post Off.ce Boi 2641 B.rmgham. Aabama 3'0910400 Tsephone 205 2501837 W. G. H airston, til Sen.or V<e President N eear opere ons Alabama power tre swnn en s,v,n November 30, 1988 Docket Nos. 50-348 50-364 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Vashington, D.C. 20555 Gentlemen Joseph M. Farley Nuclear Plant - Units 1 and 2 Miniflov Evaluation - NRC Bulletin No. 88-04 URC Bulletin No. 88-04, "Potential Safety Related Pump Loss," requires Alabama Power Company to investigate and correct, if applicable, two miniflov design concerns.

The Bulletin requires that each safety-related system be evaluated for pump-to-pump interaction during miniflov operation. If pump-to-pump interaction is possible, the system is required to be evaluated from a flov division standpoint. The Bulletin further requires an evaluation to address the adequacy of the minimum flov bypass lines for safety-related centrifugal pumps with respect to damage resulting from operation and testing.

The Bulletin reporting requirements include submittal of a short term (60 day) report which (a) summarizes the problems and the systems affected, (b) identifies the chort-term and long-term modifications to plant operating procedures er hardware that have been or are being implemented to ensure safe plant operations, (c) identifies an appropriate schedule for long-term resolution of this and/or other significant problems that are identified as a result of this bulletin, and (d) provides justification for continued operation particularly with regard to General Design Criterion 35 of Appendix A to Title 10 of the Code of Federal Regulations (10 CFR 50),

"Emergency Core Cooling" and 10 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling System for Light Vater Nuclear Pover Reactors."

Additionally, a long-term resolution report is required to be submitted within 30 days of the completion of the long-term resolution actions.

By letter dated July 8, 1988, Alabama Pover Company provided a partial response to the Bulletin and committed to provide a status of evaluation efforts by November 30, 1988. The results of evaluations on safety-related pumps are outlined in Attachient 1. All evaluations are complete with the l

exception of the evaluation required for the auxiliary feedvater (AFV) 892020:41 ss3130 d gra aooa a:000343 FDC

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. . i U. S. Nuclear Regulatory Commission November 30, 1988 Page 2 i

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pumps. Due to the increased work load placed on the pump vendor by the ,

l Bulletin, a final evaluation of the AFV pumps vill not be completed until early 1989. Alabama Power Company vill provide the results of the AFV pump i evaluation and a long-term action schedule within 60 days of evaluation a completion. Continued operation of the AFV pumps until completion of the evaluation is ju2tified in Attachment 1. For all other pumps evaluated, evaluations have shown that there is no significant pump-to-pump interaction and the current minimum flow lines are adequate.  ;

! If there are any questions, please advise.

Respectfully submitted, ,

I -

I ALABAMA P0 ER COMPANY ,

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. j l /p % V. G. Hairston, III  :

) VGH,III/REMapr-2.17 l Attachment s

cc: Mr. L. B. Long  !

g Mr. M. L. Ernst t

{ Mr. E. A Reeves I i Mr. G. F. Maxwell ,

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ATTACHMEN" 1 SYSTEM DESCRIPTION AND EVALUATION System: High Head Safety Injection / Charging Pumps: 3 Charging pumps (HHSI) per unit Miniflov

Description:

A miniflow line from each HHSI pump discharges into a common miniflov header.

Pump-to-Pump Interaction Pump-to-pump interaction is precluded by the use of a 60 GPM high resistance minimum flov orifice in the miniflow line from each HHSI pump. The individual miniflov lines combine into a low resistance common header.

Adequacy of Miniflow: The HHSI pump miniflov lines have a greater capacity than originally required by the pump vendor. The system designer, in conjunction with the pump vendor, has evaluated the adequacy of the minimum flov lines. The required thermal minimum flov is substantially below the expected pump flov for all operating I modes. The required mechanical minimum flov to prevent hydraulic instability and mechanical damage is lover than the expected minimum flov vhich results from each mode of operation.

System: Lov Head Safety Injection / Residual Heat i Removal (RHR)

Pumps: 2 RHR pumps per unit Miniflow

Description:

Each RHR pump has an independent miniflov  !

line, Pump-to-Pump Interaction: Pump-to-pump interaction is precluded by use of independent miniflov lines. l Adequacy of Miniflov: The RHR pump miniflov lines have a greater r capacity than originally required by the pump l vendor. The system designer, in conjunction l vith the pump vendor, has evaluated the adequacy of the minimum flov lines. The required thermal minimum flov is substantially l belov the expected pump flov for all operating i modes. The required mechanical minimum flov to prevent hydraulic instability and mechanical damage is lover than the expected  !

minimum flov vhich results from each mode of l operation. l i

Systems Containment Spray (CS) l Pumps: 2 CS pumps per unit l i

. . Art chment 1

• System Descriptions and Evaluatitns

• Paga 2 Miniflov

Description:

Each CS pump has a recirculation line which joins to form a common return header to the Refueling Vater Storage Tank (RVST). Normally locked closed valves are provided in tFe recirculation lines and in the common header for isolation. This piping arrar.gement is utilized as a means to test the spray pumps without spraying into containment. In addition, each pump has a spray eductor  ;

recirculation line. 1 Pump-to-Pump Interaction: During accident situations, and all surveillance testing except for the "Spray and Phase B Actuation Test", the operation of the two trains is completely independent, with the l exception of a common portion of the suction line from the RVST. The pumps can develop cufficient discharge pressure to exceed the containment design pressure such that there is no possibility of deadheading a pump during i spray actuation. During individual pump surveillance testing (Spray Pump Monthly, ,

Quarterly and Annual Testing) the spray header is isolated, however, each pump's miniflow path to the RVST is available to prevent '

deadheading. During the "Spray and Phase B Actuation Surveillance Test" the discharge ,

headers are isolated, and the two pumps are  !

run simultaneously in parallel with flov directed to the common miniflov line. The  !

surveillance procedure requires that the time the spray pumps are run in parallel be held to a maximum of 1 minute. The resistance in the common miniflow path is high relative to that ,

in the individual line. Hence, given a l mismatch between the pump developed heads. It ,

is possible for the pressure at the junction '

point (where the discharge heads combine) to be high enough to prevent one pump from recirculating to the RVST. This condition is i considered acceptable because (1) the pumps I only run for one minute maximum and (2) the l spray eductor recirculation line in essence l provides an individual and independent mintaum I flov path.

L Adequacy of Miniflov The system designer, in conjunction with the [

pump vendor, has evaluated the adequacy of the i ninimum flov lines. The required thermal ,

minimum flov is substantially below the {

expected pump flev for all operating modes. l The required mechanical minimum flov to (

prevent hydraulic instability and mechanical i damage is lover than the expected minimum flov !

vhich results from each mode of operation.  ?

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. . Att:chment 1 ,

. System Descriptionr. cnd Evaluatiens Paga 3 .

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Systems Auxiliary Feedvater (AFV)  !

Pumps: 2 motor driven ATV pumps per unit 1 turbine driven AFV pump per unit Miniflow

Description:

A continuously open miniflov line from each AFV pump discharges into a common miniflov '

header.

Pump-to-Pump Interaction: Pump-to-pump interaction is precluded by the use of a high resistance minimum flow orifice '

and check valve in the miniflov line from each  !

AFV pump. The miniflow orifice was supplied i by the pump vendor and installed following the  ;

vendor's technical manual. j r

l Adequacy of Miniflove The use of the vendor supplied miniflov i l

orifice, installed following the vendor's technical manual, has resulted in a miniflov 4 capacity which meets original requirements. t

. The pump vendor, in conjunction with the  ;

system designer, is evaluating the adequacy of i the miniflov line for long-term operation.  !

Due to the pump vendor's workload and '

engineering staff size, the evaluation is not

expected to be completed until early 1989.

a Continued operation of the MDATV and TDAFV ,

pumps is justified for the near term based on i the following considerations: l 1

) (a) Damage of the pumps due to internal l l

recirculation has not been experienced to ,

j date, nor is the manufacturer avare of  !

minimum flow problems with similar type

, pumps in other plants.

(b) The minimum flow rates are not affacted I because of interaction during parallel l operation. This is a result of the high  !

I flow resistances of the individual l minimum flov orifices, i

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j (c) The degradation due to operation with lov  ;

minimum flow rates is gradual. Because i j of this and because the pumps operate i a

infrequently at minimum flov, life of the l

) pump vould not be degraded with less than [

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desirable miniflov. j Furthermore, required routine (

maintenance, inspections and surveillance {

testing are expected to detect any l excessive vear or damage vell before  !

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system performance is degraded.  :

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Atttchment 1 System Descriptic;s and Evaluations Pag 3 4 i

System Component Cooling Vater (CCV)  !

l Pumps: 3 CCW pumps per unit  !

Miniflow

Description:

A separate recirculation line from the CCV  ;

pump discharge to the CCV pump suction is provided for each pump. The recirculation I line contains a minimum flow orifice provided i

by the pump manufacturer. A check valve is i located in the discharge line downstream of r the recirculation line connection for each [

pump. >

i Pump-to-Pump Interaction: Pump-to-pump interaction is precluded by ,

prt iding a separate recirculation line for (

eat'. pump.

! Adequacy of Miniflow: Duri.1g normal operation, the miniflow line is isolated and the system designer has t 2

determined that the system flovrate is

) adequate to prevent pump degradation. The .

Unit 2 Inservice Testing Program contains the  !

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only known requirement to run the CCV pumps (

solely on miniflow. The Unit 2 Inservice [

Testing Program is expected to be revised as ,

part of the second ten year update (spring t 1989 outage) to eliminate the requirement.

)l 1

The Unit 1 Inservice Testing Program has I

l already been revised to eliminate the t requirement. The system designer, in  :

i conjunction with the pump vendor, has determined that the nintflow line is adequate provided that the duration of operation is 1 minimited.

I i t System Service Vater (SV) [

! Pumps: 5 SV pumps per unit l i

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• Miniflov

Description:

The 5 SV pusps are divided as illustrated in l 4 Figure 1. SV pumps A and I are A train pumps.  ;

! SV pumps D and E are B train pumps. SV pump C  !

1 is a sving pump which may be aligned to the A (

or 5 train. A common miniflov is provided for 7 pumps A and B. A common miniflov is provided  !

for pumps D and E. Pump C is provided with its own miniflov line. The control valves for all of the mintflov lines are set to open at  ;

i 130 psig. Additionally the SV system contains l 1 a 24 inch dilution bypass line which i i ultimately discharges to the river. The l

! dilution bypass line control valve opens St  ;

j 100 psig. (

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. . Att cheent 1 i Systee Descriptions and EvaluatiCns  :

Page 5 .

l Pump-to-Pump Interaction: The SV system is not designed to preclude l pump-to-pump interaction while on miniflow. L Operation of pumps A and B or pumps D and E, l in conjunction with pump C, could result in  ;

multiple pumps discharging to a common header  ;

with miniflow protection. Plant operators are procedurally directed to start and secure SV  !

pumps in order to maintain SV header pressure i between 70 to 100 psig. Vith the procedural guidance that is available to operators, pump-to-pump interaction in the SV header is ,

precluded.  !

I Adequacy of Miniflow: The pump vendor has stated that "we do not '

recommend the minimum continuous throttled flow to be less than thirty-five percent (35%)  :

of the pump capacity at Best Efficiency Point }

(BEP). This calculates to approximately 3150 GPM..." The SV pump miniflow lines are sized 3 to handle 3150 GPM/ pump. Additionally, the  ;

dilution bypass line, which opens before the l SV pump miniflow line, provides additional l protection for SV pumps during operation. The t system designer, in conjunction with the pump vendor, has determined that there are no circumstances under which the SV pumps vill j operate at flow rates lov enough to adversely ,

affect the pumps.

System Diesel Generator (DG) Fuel Oil (TO) l t

Pumps: 5 manual FO transfer pumps j 5 automatic To transfer pumps  ;

r Miniflov

Description:

The DG F0 system has no miniflow lines. The F0 transfer pumps take a suction on the T0 storage tanks and discharge to the day tanks or other F0 storage tanks. l l-Pump-to-Pump Interaction: If the FO transfer pumps are operated in parallel, possible dead-heading of a pump  !

could occur. Procedures do not provide for f operating pumps in parallel. A precaution j against parallel operation has been added to  ;

the operating procedure. Therefore,  ;

pump-to-pump interaction is precluded.  ;

t System Boric Acid Transfer (BAT) System Pumps: 2 Boric Acid Transfer Pumps per unit

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Attcchment 1 System Descriptitns cnd Ev0lutticns Paga 6 Miniflov 9cscription: Each BAT pump has an independent m!niflov line which recirculates to the boric acid tanks.

However, the system may be physically aligned such that both pumps discharge to the same miniflow line.

Pump-to-Pump Interaction: Pump-to-pump interaction is precluded through the use of procedures which prevent the operator from starting both pumps and operating them through the same miniflow line.

Adequacy of Miniflov The system designer, in conjunction with the pump vendor, has evaluated the adequacy of the minimum flov line. The required thermal minimum flov is substantially belov the expected pump flov for all operating modos.

The required mechanical minimum flov to prevent hydraulic instability and mechanical damage is lover than the expected minimum flov vhich results from each mode of operation.

Systems Spent Fuel Pool Cooling Pumps: 2 Spent Fuel Pit Pumps per unit Miniflov

Description:

The Spent Fuel Pit system does not include a miniflow provision for these pumps.

Pump-to-Pump Interaction: Operating procedures provide for only one spent fuel pool cooling loop on service at a time. Therefore, pump-to-pump interaction is precluded by operating only one pump at a time.

Adequacy of Minifleva Normal operation of the Spent Fuel Pool Cooling system is to throttle flov across the pump to 54 psid. This operational philosophy results in system pumps operating in the vicinity of the best efficiency point. Since these pumps are not operated at flovs that vould require miniflov, no additional action is required.

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