ML20153A873
| ML20153A873 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 07/08/1988 |
| From: | Hairston W ALABAMA POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-88-004, IEB-88-4, NUDOCS 8807120643 | |
| Download: ML20153A873 (12) | |
Text
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r Alabama Power Company 600 North 18th Street Post Othee Box 2641 Dirmingham. Alabama 352914400 Telephone 2052501837 W. G. Hairston, til Senior Vice President Near Operatens
. Alabama Power the southern electnc systorn ~
July 8, 1988 Docket Nos. 50-348 50-364 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Vashington, D.C.
20555 Gentlemen:
Joseph H. Parley Nuclear Plant - Units 1 and 2 Hiniflov Evaluation - NRC Bulletin No. 88-04 NRC Bulletin No. 88-04, "Potential Safety'Related Pump Loss," required Alabama Power Company to investigate and correct, if applicable, two miniflow design concerns.
The Bulletin required that each safety-related system be evaluated for pump-to-pump interaction during miniflow operation.
If pump-to-pump interaction was possible, the system was required to be evaluated from a flow division standpoint. The Bulletin further required 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 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling System for Light Vater 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.
It is the opinion of Alabama Power Company that the pumps within the scope of this Bulletin have operated in a satisfactory manner and vill continue to operate in a satisfactory manner until the issues identified in NRC Bulletin 88-04 are resolved.
Bulletin scoped pumps included in' the Technical Specifications are tested on a periodic basis where degradaticn in pump performance vould be identified and addressed.
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l U. S. Nuclear Regulatory Commission July 8, 1988 Page 2
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Based on previous surveillance testing, no pump degradation has been identified which could be attributed to the mechanisms discussed by the Bulletin.
Vestinghouse notified utilities of a potential generic concern regarding ECCS pumps utilizing a common miniflow path. On receipt of Vestinghouse letters dated October 26, 1987 and November 30, 1987, Alabama Power Company commenced an evaluation of the miniflow design on the Residual Heat Removal (RHR) pumps and the Charging (HHSI) pumps.
The evaluation concluded, with Westinghouse concurrence, that pump-to-pump interaction was precluded for the RHR pumps and HHSI pumps, and that the miniflov lines were adequately sized.
It is recognized that long-term miniflow operation is an issue that requires additional evaluation; however, no immediate modifications are requ' red at this time. identifies systems with safety-related centrifugal pumps, provides a brief description of the miniflow design, and identifies any problems vith pump-to-pump interaction or inadequate miniflow.
Procedure modifications, along with areas continuing to be investigated are also indicated. Attachment 2 provides a long-term resolution schedule and Attachment 3 provides a justification for cuntinued operation concerning the Emergency Core Cooling System.
If there are any questions, please advise.
Respectfully submitted, ALABAMA POVER COMPANY
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l W. G. Hairston, III VGH,III/ REM: dst-V8.36 Attachments cc: Mr. L. B. Long SVORN TO AND SUBSCRIBED 38 FORE HE Dr. J. N. Grace Mr. E. A. Reeves THI N DAY OF du u
,1988 Hr. V. H. Bradford M b (&
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SYSTEM DESCRIPTION AND EVALUATION System:
High Head Safety Injection / Charging Pumps:
3 Charging pumps (HHSI) per unit 1
Miniflov
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 minimum flow orifice in the miniflow line from each HHSI line.
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, is evaluating the adequacy of the miniflov line for long-term operation.
Systems Lov Head Safety Injection / Residual Heat Removal (RHR)
Pumps:
2 RHR pumps per unit' Miniflov
Description:
Each RHR pump has an independent miniflow line.
Pump-to-Pump Interaction:
Pump-to-pump interaction is precluded by use of independent miniflow lines..
Adequacy of Miniflow:
The RHR pump miniflov lines have a greater capacity than originally required by the pump vendor.
The system designer, in conjunction with the pump vendor, is evaluating the adequacy of the miniflow lines for long-term i
operation.
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Attsch:cnt 1 System Descriptions and Evaluations Page 2 System:
Pumps:
2 CS pumps per unit-Miniflov
Description:
Each CS pump has a recircu....on line which joins to form a common return header to the Refueling Vater Storage Tank-(RUST). 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.
Pump-to-Pump Interaction:
During plant surveillance testing, one test configuration is a CS pump operating on recirculation while another test configuration for Unit 1 is full flow to the refueling cavity.
Surveillance procedures do not provide for operating pumps in parallel and it is not our practice to operate these pumps in parallel.
However, a precaution against parallel operation does not exist but will be added to the surveillance procedures.
The-only time that both pumps'are running is
'911oving a Phase B signal.
During this time, sere is no interaction between the two pumps dischcrging piping.
Each pump injects into independent discharge headers which injects into containment. Therefore, pump-to-pumn interaction is precluded.
Adequacy of Miniflov:
The system designer, in conjunction with the pump vendor, is evaluating Item 3 of the Bulletin for CS pump operation on the recirculation line for the surveillance testing.
Systems Auxiliary Feedvater (AFV)
Pumps:
2 motor driven AFV pumps per unit 1 turbine driven AFV pump per unit Miniflov
Description:
A continuously open miniflov line from each j
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 miniflow line from each AFV pump. The miniflov orifice was supplied by the pump vendor and installed following the vendor's guidance.
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Attachunt 1 System Descriptions and Evaluations Page 3 1
i Adequacy of Miniflov:
The use of the vendor supplied miniflow orifice, installed following the vendor's guidance, 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 miniflow line for long-term operation.
System Component Cooling Vater (CCV)
Pumps:
3 CCW pumps per unit Miniflov
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 mir.imum flow orifice provided by the pump manufacturer. A check valve is located in the discharge line downstream of the recirculation line connection for each j
pump.
Pump-to-Pump Interaction:
Pump-to-pump interaction is precluded by providing a separate recirculation line for each pump.
Adequacy of Miniflow:
Since the minimum flov orifice was provided by the pump vendor, the recirculation line meets the original pump vendor requirements.
However, the system designer, in conjunction vith the pump vendor, is evaluating Item 3 of the Bulletin for CCV pump operation on the recirculation line during surveillance testing. Currently,.the Unit 1 CCV pumps are not operated on recirculation.
Unit 2 CCV pumps are operated on recirculation for surveillance testing only.
Systems Service Vater (SV)
Pumps:
5 SV pumps per unit Miniflov
Description:
The 5 $V pumps are divided as illustrated in i
Figure 1.
SV pumps A and B are A train pumps.
SV pumps D and B are B train pumps. SV pump C is a sving pump which may be aligned to the A or B train.
A common miniflov is provided for pumps A and B.
A common miniflow is provided for pcmps D and E.
Pump C is provided with its own miniflov line. The control valves for
Attach 00nt 1 System Descriptions and Evaluations Page 4 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 river. The dilution bypass line control valve opens at 100 psig.
Pump-to-Pump Interaction:
The SV system is not designed to preclude pump-to-pump interaction while on miniflow.
Pumps A and B or pumps D and E, in conjunction with pump C, could discharge to a co 7
miniflow line.
However, with the 1s_.
dilution bypass line control valv:
~t tc open at 100 psig, it would be unlikely
.at the SV pump miniflov line would open at-130 psig.
Additionally, plant opert. tors are procedurally directed to start and secure SV pumps la order to maintain SV header pressure between 70 to 100 psig.
Vith the dilution bypass and the procedural guidance that is available to operators, pump-to-pump intecaction in the SV header is precluded.
Adequacy of Miniflov:
The pump vendor has stated that "we de 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 miniflov lines are sized to handle 3150 GPM/ pump. Additionally, the dilution bypass line, which opens before the SV pump miniflov line, provides additional protection for SV pumps during operation. The system designer is evaluating the adequacy of the miniflow line for long-term operation.
System:
Diesel Generator (DG) Fuel Oil (F0)
Pumps:
5 manual F0 transfer pumps 5 automatic F0 transfer pumps Miniflow
Description:
The DG F0 system has no miniflow lines. The F0 transfer pumps take a r.uction on the F0 storage tanks and discharge to the day tanks or other F0 storage tanks.
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-Attccbt:nt 1 System Descriptions and Evaluations Page 5 Pump-to-Pump Interaction:
If the FO transfer pumps are operated in parallel, possible dead-heading of a pump i
could occur.
Procedures do not provide-for j
operating pumps in parallel and it is not our practice to operate these pumps in parallel.
However, a precaution against parallel j
operation does not exist but vill be added to the operating procedure. Therefore, pump-to-pump interaction is precluded.
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System:
Boric Acid Transfer System Pumps:
2 Boric Acid Transfer Pumps per unit As a result of normal' operating practice, the Boric Acid Pumps operate much of the time on miniflov. This operating configuration has not resulted in pump degradation.
- However, these pumps vill be evaluated in accordance vith Bulletin 88-04 by.the system designer and pump vendor.
System:
Spent Fuel Pool Cooling Pumps:
2 Spent Fuel Pit Pumps per unit The Spent Fuel Pit system does not include a miniflow provision for these pumps.
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 flow rates significantly above those required for miniflow operation.
Since these pumps are not operated at flows that vould require miniflow, no additional action is required.
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ATTACRMENT 2 LONG-TERM RESOLttfION SCHEDULE Alabama Pover Company's goal is to identify long-term minimum pump flow requirements for safety-related centrifugal pumps by October 1, 1988.
However, because of the required system designer / pump vendor interface an(
the increased workload placed on pump vendors by this bulletin, a delay is possible.
Alabama Power Company anticipates that it vill take approximately 2 months to determine the required corrective action to resolve areas of concern identified by the system designer / pump vendor.
A schedule to complete long-term actions vill be provided to the NRC within 60 days of completion of the evaluation required to identify any required corrective actions.
By November 30, 1988, Alabama Power Company vill either provide the schedule for long-term actions or provide a status of the evaluation efforts.
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o ATTACHMENT 3 i
JUSTIFICATION FOR CONTINUED OPERATION (JCO)
CONCERNING THE EMERGENCY CORE COOLING SYSTEM
Background
NRC Dulletin 88-04 Item 4(d) requested justification foc continued operation particularly with regard to General Design criterion 35 of Appendix A to 10CFR50 and to 10CFR50.46 for the Emergency Core Coeling System.
By letters ALA-07-827 dated October 26, 1987 and ALA-87-891 dated. November 30, 1987, Vestinghouse identified potential concerns with the RHR and HHSI miniflow designs. The primary concerns vere that:
- 1) if multiple pumps operated on a common miniflow header, a strong pump could possibly dead-head a veaker pump, or 2) whether the installed miniflow capacity was adequate for operation of a single pump.
NRC Bulletin 88-04 identified two design concerns. The first concern involves potential dead-heading of one or more safety-related pumps with common miniflow lines or other piping configurations that do not preclude pump-to-pump 'nteraction during miniflov operation. The second concern is whether the i. stalled miniflow capacity is adequate for even a single pump in operation.
Evaluation:
This JC0 addresses the two NRC Bulletin 88-04 design concerns for Farley Nuclear Plant Units 1 and 2 HHSI and LHSI pumps. The potential for pump-to-pump interaction has been reviewed by Vestinghouse and it has been determined that Parley Nuclear Plant has a functional layout which prevents ECCS pumps from dead-heading on miniflov. Actual miniflov values were evaluated by Vestinghouse and determined to be adequate.
Surveillance testing has not revealed abnormal pump degradation which could be attributed to inadequate miniflov and continuing surveillance testing vill provide data to detect degradation.
In response to Vestinghouse let ters ALA-87-827 and ALA-87-891, Alabama Power Company requested that Vestinghouse evaluate this issue for Farley Nuclear Plant.
A review of technical manuals and startup testing revealed the following:
Required Heasured Flov Through Miniflow Pump Minimum Flov During Start-Up Testing 1
i 1A Charging /HHSI 60 GPM 68.9 GPM 1B Charging /HHSI 60 GPM 67.2 GPM 1C Charging /HHSI 60 GPH 67.7 GPM 1A RHR/LHSI 500 GPM 521 GPM 1B RHR/LHSI 500 GPM 515 GPM
y.
f Attcchment 3 Justificatien fer C:ntinued Opsrotien (JCO)
Concerning the Emergency Core Cooling' System
.Page 2 Required Measured Flow Through Miniflov Pump Minimum Flov
.During Start-Up Testing-2A Charging /HHSI 60 GPM 69.0 GPM 2B Charging /HHSI 60 GPM 69.6 GPM 2C Charging /HHSI 60 GPM 69.15 GPM 2A RHR/LHSI 355 GPM*
590 GPM 2B RHR/LHSI 355 GPM*
580 GPM
- Technical Manual provides that pump may be run at 355 GPM for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> per month over a 40 year plant life and six hours total for one month at startup.
Each RHR pump at Farley Nuclear Plant has its own independent miniflow path branching from independent discharge lines and there is a check valve (8716A and B) dovnstream of each miniflov line at the pump discharge.
These check valves act as a means of pressure isolation in the veaker pump path, and because the isolation occurs beyond the miniflow inlets, the veaker pump can operate on miniflow at the required flovrate.
Therefore, it can be concluded that there is no potential for a strong pump to dead-head a veaker pump in the LHSI system.
The three Charging /HHSI pumps discharge into a common miniflow line and the miniflov line for each pump discharge contains a flow orifice designed to permit 60 GPM per pump on miniflov. Vestinghouse calculations, with all three Charging /HHSI pumps running and based on the measured miniflow rates through each pump and the current plant layout, shoved that the effect of multiple parallel pumps running at the same time has negligible impact on the flov through each pump's miniflow line.
For all combinations of pumps running, miniflov for each pump vas confirmed to be in excess of 60 GPM.
Consequently, it is concluded that no Charging /HHSI pump dead-heading vill occur at Farley Nuclear Plant.
For a large break LOCA, miniflov operation for long periods of time is not expected because discharge vill be to the reactor coolant system which depressurizes to a lov value relatively early in the accident.
Pump flovrates vill be greater than those requiring miniflow protection.
Furthermore, procedures for large and small break LOCA require that the charging pump miniflow valves be opened when RCS pressure increases above 1900 psig. Cooling vater to the LHSI heat exchanger is also checked during an accident.
Establishment of cooling vater to the LHSI heat exchanger vould prevent temperature rise in the RHR system during miniflov operation.
Mechanical minimum flov vear and aging effects, if present, are long term in nature and are expected to result in gradual vear to the pumps.
Surveillance testing at Farley Nuclear Plant for the HHS1 and LHSI pumps has not identified any increase in pump degradation which could be attributed to inadequate miniflow.
Periodic surveillance testing required by technical specifications vill continue to provide data that vould detect pump degradation.
Attcchment 3
' Justification for C:ntinutd Opsraticn (JCO)
.Concerning the. Emergency Core Cooling System
- Page 3 Conclusion Continued operation with regard to IOCFR50.46 and General Design Criterion.
35 is justified based on previous design reviews, expected pump response during accident conditions, and surveillance testing.
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