ML20247B995

Suppls Response to NRC Bulletin 88-004, Potential Safety-Related Pump Loss. All Evaluations of Pumps Complete Except for Auxiliary Feedwater Pumps Which Will Be Provided within 60 Days of Completion of Evaluation

ML20247B995
Person / Time
Site:	Farley
Issue date:	03/23/1989
From:	Hairston W ALABAMA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
IEB-88-004, IEB-88-4, NUDOCS 8903300096
Download: ML20247B995 (9)

Text

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, Alabama Power Company 40 inverness Center Parkway Post Office Box 1295 Birmingham. Alabama 35201 Telephone 205 868-5581 W. G. Hairston, til Senior Vice President h

Nuclear Operations M8ballla Power the southem electnc system March 23,1989 Docket Nos. 50-348 50-364 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Vashington, D.C. 20555 Gentlemen Joseph M. Parley Muclear Plant - Units 1 and 2  ;

Miniflov Evaluation - NRC Bulletin No. 88-04 By letter of November 30, 1988, Alabama Power Company provided additional I information as committed in its July 8, 1988 response to NRC Bulletin No.

88-04. This letter which provided an update on Alabama Power Company's response to the bulletin was not submitted under " oath or affirmation". At the verbal request of the Farley NRC Project Manager, however, the November 30, 1988 letter is being resubmitted under " oath or affirmation".

NRC Bulletin No. 88-04, " Potential Safety Related Pump Loss," requires  ;

Alabama Power Company to investigate and correct, if applicable, two j miniflow design concerns. l The Bulletin requires that each safety-related system be evaluated for pump-to-pump interaction during miniflov operation. If pump-to-pump i interaction is possible, the system is required to be evaluated from a flow division standpoint. The Bulletin further requires an evaluation to address the adequacy of the minimum flow 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 short-term and long-term modifications to plant operating procedures or 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 CFP. 50.46, " Acceptance Criteria for Emergency Core Cooling Systehi for Light Water Nuclear Power Reactors."

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

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8903300096 890323 1 PDR ADOCK 05000348 I 0 PDC g

'U. S. Nuclear Regulatory Commission March 23, 1989 Page 2 By letter dated July 8, 1988, Alabama Power 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 Attachment 1. All evaluations are complete with the exception of the evaluation required for the auxiliary feedvater (AFV)-

pumps. Due to the increased work load placed on the pump vendor by the Bulletin, a final evaluation of the AFV pumps is scheduled to be completed in May, 1989. Alabama Power Company vill provide the results of the AFV pump evaluation and a long-term action schedule within 60 days of evaluation completion. Continued operation of the AFV pumps until completion of the evaluation is justified in Attachment 1. For all other i

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, A1.ABAMA POVER COMPANY lb. . ha $

V. G. Hairston, III VGH,III/ REM:pr-5.16 Attachment cc: Mr. S. D. Ebnetter Mr. E. A. Reeves Mr. G. F. Maxwell SVORN TO AND SUBSCRIBED BEFORE ME THIS J3 d DAY of %m[ , 1989 dluna(] Notary lhdf}L-}</rf/] Public My Commission Expires DEEN

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

Description:

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

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

Adequacy of Miniflow: The HHSI pump miniflow 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 flow lines. The required thermal minimum flow is substantially below the expected pump flow for all operating modes. The required mechanical minimum flow to prevent hydraulic instability and mechanical damage is lower than the expected minimum flow which results from cach mode of operation.

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

Pumps: 2 RHR pumps per unit Miniflow

Description:

Each RHR pump has an independent miniflow line.

Pump-to-Pump Interaction: Pump-to-pump interaction is precluded by use f of independent miniflov lines.  !

Adequacy of Miniflow: The RHR pump miniflow lines have a greater {

capacity than originally required by the pump i j vendor. The system designer, in conjunction i with thin pump vendor, has evaluated the <

adequacy of the minimum flow lines. The '

requireo thermal minimum flow is substantially .

below the expected pump flow for all operating l modas. The required mechanical minimum flov s to prevent hydraulic instability and i mechanical damage is lover than the expected .

minimum flow which results from each mode of operation.

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

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Attechment.l' Syst03 Deacriptiens cnd Evaluations

'P g2 2 Miniflow

Description:

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

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 exception of a common portion of the suction line from the RWST. The pumps can develop sufficient discharge pressure to exceed the containment design pressure such-that there is no possibility of deadheading a pump during spray actuation. During individual pump surveillance testing (Spray Pump Honthly, 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 l Actuation Surveillance Test" the discharge headers are isolated, and the two pumps are  !

l run simultaneously in parallel with flov directed to the common miniflow line. The

, surveillance procedure requires that the time i 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 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 considered acceptable because (1) the pumps only run for one minute maximum and (2) the spray eductor recirculation line in essence provides an individual and independent minimum flow path.

Adequacy of Miniflow: The system der.igner, in conjunction with the I pump vendor, has evaluated the adequacy of the l minimum flov lines. The required thermal I minimum flow is substantially below the expected pump flow for all operating modes.

The required mechanical minimum flow to prevent hydraulic instability and mechanical j damage is lower than the expected minimum flov '

l vhich results from each mode of operation.  ;

Attach::nt 1

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.Systs2 D2scriptions and Evaluations

• Psg2 3 Systems Auxiliary Feedvater_ (AFW) i Pumps: 2 motor driven AFV pumps per unit i 1 turbine driven AFV pump per unit .!

Miniflow

Description:

A continuously open miniflow line from each AFV pump discharges into a common miniflow 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 "

by the pump vendor and installed following the vcndor's technical manual.

Adequacy of Miniflow: The use of the vendor supplied miniflow orifice, installed following the vendor's technical manual, has resulted in a miniflow capacity which meets original requirements.

The pump vendor, in conjunction with the .

system designer, is evaluating the adequacy of 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.

Continued operation of the MDAFV and TDAFV pumps is justified for the near term based on l the following considerations:

(a) Damage of the pumps due to internal recirculation has not been experienced to date, nor is the manufacturer aware of minimum flow problems with similar type pumps in other plants.

(b) The minimum flow rates are not affected because of interaction during parallel operation. This is a result of the high flow resistances of the individual j minimum flow orifices.

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(c) The degradation due to operation with low minimum flow rates is gradual. Because ,

of this and because the pumps operate I infrequently at minimum. flow, life of the i pump would not be degraded with less than l desirable miniflow. I i

Furthermore, required routine i maintenance, inspections and surveillance testing are expected to detect any l excessive wear or damage well before system performance is degraded. 1

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Attechment 1 l Systc3 Descriptions cnd Evaluations i

• P ga 4 l Systems Component Cooling Vater (CCV) ,

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Pumps: 3 CCV 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 line contains a minimum flow orifice provided by the pump manufacturer. A check valve is located in the discharge line dovnstream of the recirculation line connection for each pump.

Pump-to-Pump Interaction: Pump-to-pump interaction is precluded by providing a separate recirculation line for each pump.

Adequacy of Miniflow: During normal operation, the miniflow line is isolated and the system designer has determined that the system flovrate is adequate to prevent pump degradation. The Unit 2 Inservice Testing Program contains the 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 1989 outage) to eliminate the requirement.

The Unit 1 Inservice Testing Program has already been revised te eliminate the requirement. The system designer, in conjunction with the pump vendor, has determined that the miniflow line is adequate provided that the duration of operation is minimized.

System: Service Water (aV)

Pumps: 5 SV pumps per unit Miniflow

Description:

The 5 SV pumps are divided as illustrated in Pigure 1. SV pumps A and B are A train pumps.

SV pumps D and E are B train pumps. SV pump C is a sving pump which may be aligned to the A or B train. A common miniflow is provided for pumps A and B. A common miniflow is provided for pumps D and E. Pump C is provided with 1 its own miniflow line. The control valves for all of the miniflow lines are set to open at 130 psig. Additionally the SV system contains a 24 inch dilution bypass line which {

ultimately discharges to the rive *. The dilution bypass line control va7ve opens at 100 psig.

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Attschment 1 Systea Descriptions cnd Evoluttions P ga 5 l 1

Pump-to-Pump Interaction: The SV system is not designed to preclude )

pump-to-pump interaction while on miniflow. {

Operation of pumps A and B or pumps D and E,  ;

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 between'70 to 100 psig.. With'the procedural j guidance.that is available to operators, I pump-to-pump interaction in the SV header is j 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  ;

to handle 3150 GPM/ pump. Additionally, the (

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

System Diesel Generator (DG) Fuel Oil (FO)

Pumps: 5 manual FO transfer pumps 5 automatic F0 transfer pumps Miniflow

Description:

The DG F0 system has no miniflow lines. The F0 transfer pumps take a. suction on the F0 storage tanks and discharge to the day tanks or other F0 storage tanks.

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Pamp-to-Pump Interaction: If the F0 transfer pumps are operated in parallel, possible dead heading of a pump ]-

could occur. Procedures do not provide for operating pumps in parallel. A precaution against parallel operation has been added to the operating procedure. Therefore, j pump-to-pump interaction is preclude /

System: Boric Acid Transfer (BAT) System  !

Pumps: 2 Boric Acid Transfer Pumps per unit

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l Attach: nt I Systcm Descriptions end Ev21untiens ,

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," 'P gs 6 l

l Miniflow

Description:

Each BAT pump has an independent miniflow line l which recirculates to the boric acid tanks. -

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

l Pump-to-Pump Interaction: Pun:p-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 Miniflow: 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 below the expected pump flow for all operating modes.

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

System: Spent Fuel Pool Cooling Pumps: 2 Spent Fuel Pit Pumps per unit Miniflow

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 i time.

Adequacy of Miniflow: Normal operation of the Spent Fuel Pool Cooling system is to throttle flow 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 flows that would require miniflow, no additional action is required.

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