ML20205J843
| ML20205J843 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 10/25/1988 |
| From: | Hairston W GEORGIA POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| HVS-94, IEB-88-004, IEB-88-4, NUDOCS 8810310498 | |
| Download: ML20205J843 (6) | |
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1331ti X7GJ17-V110 October 25, 1988 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington 0.C.
20555 PLANT V0GTLE - UNITS 1, 2 NRC DOCKETS 50-424, 50-425 0PERATING LICENSE NPF-68 CONSTRUCTION PERMIT CPPR-109 RESPONSE TO BULLETIN 83-04 SAFETY-RELATED PUMP LOSS Gentlemen:
The subject NRC Bulletin (NRCB) 88-04, dated May 5,1988, "Potential Safety-related Fump Loss", requested that Georgia Power Company (GPC) investigate and correct, as applictble, two concerns related to the design of the minimum flow (miniflow) lines for safety-related centrifugal pumps.
Specifically, the concerns involved the adequacy of the miniflow capacity, and the potential for a pump to deadhead when it is operating in mintflow mode in parallel with another pump.
GPC provided an initial response to the NRCB on July 11, 1988.
That response provided justification for continued operation pending subn.ittal of a sipplemental response scheduled for November 1,
1988.
The supplemental tesponse is provided as the Enclosure to this letter.
As explained in the Enclosure, we are still awaiting the results of one pump vendor's analysis.
He expect to be able to provide that additional information to the NRC by December 15, 1988.
If you have any further questions in this regard, please contact this office.
Mr. W. G. Hairston, III states he is Senior Vice President of Georgia Power Company and is authorized to execute this oath on behalf of Georgia Power Company, and to the best of his knowledge snd belief, the facts set forth in this letter are true.
GEORGIA POWER COMPANY By: bM-k v_A H. G. Hairston, III Sworn to and subscribed before me this 25th day of October, 1988.
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Georgit1 Power d U. S. Nuclear Regulatory Comission October 25, 1988 Page Two
Enclosure:
Plant Vogtle Response to Bulletin 88-04 HJ B:j t' c: Georaia Power CompADy Mr. P. D. Rice, Vice President and Vogtle Project Director Mr. G. Bockhold, Jr., General Manager - Plant Vogtle Mr. J. P. Kane, Manager Vogtle Engineering and Licansing GO-NORMS U. S. Nuclear Fagulatory Comission. Washin2 ton D.C.
Mr. J. B. Hopkins, Licensing Project Harager - Vogtle U. S. Nuclear Reculatory Comission. Reaion II
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Mr. H. L. Ernst, Acting Regional Administrator Mr. J. F. Rogge, Senior Resident Inspector Operations - Vogtle t
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1331U j
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t Georgi tIbwer b ENCLOSURE
.k PLANT V0GTLE - UNITS 1, 2
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NRC DOCKETS 50-424, 50-425 t
OPERATING LICENSE NPF-68 l
CONSTRUCTION PERMIT CPPR-109 L
RESPONSE TO BULLETIN 88-04 SAFETY-RELATED PUMP LOSS i
f PLANT V0GTLE RESPONSE TO BULLETIN 88-04 NRCB 88-04 ACHON ITEM 1 Promptly determine whether or not any safety-related system has a pump and piping system configuration that does not preclude pump-to-pump interaction during miniflow operation and could therefore result in deadheading of one or more of the pumps.
RESPONSE TO NRCB 88-04 J.Cll0N ITEM 1 The following safety-related centrifugal pumps installed at Plant Vogtle Units 1 and 2 were evaluated
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Residual Heat Removal Pump - Ingersoll-Rand Model 8x20MDF Safety Injection Pump - Pacific Pump Model 31n-JHF Centrifugal Charging Pump - Pacific Pumo Model 2 1/2 RL-IJ Boric Acid Transfer Pump - Chempump Model GVH-10K Containment Spray Pump - Goulds Pump Model 34150V i
Motor Driven Auxiliary Feedwater Pump - Ingersoll-Rand Model 4HMTA6 Turbine Driven Auxiliary Feedwater Pump. Ingersoll-Rand Model 6HMTAS i
i The Residual Heat Removal and Auxiliary Feedwater (AFH) pumps have Individual miniflow lines and configurations which preclude pump to pump interaction; therefore, the potential for a stronger pump to deadhead a i
weaker parallel pump does not exist.
The other pumps listed above share i
some portion of their miniflow line in common with a parallel pump.
I NRCB 88-04 ACTION ITEM 2 If the situation described in Item I exists, evaluate the system for flow
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division taking into consideration (4) the actual line and componsnt i
resistances for the as-built configuration of the identified system; (b) the head versus flow characteristics of the installed pumps, including actual test data for "strong" and "weak" pump flows; (c) the effect of test instrument errar and reading error; and (d) the worst case allowances for deviation of pump test parameters as allowed by the American Society of
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Mechanical Engineers Coller and Pressure Vessel Code (ASME Code) Section t
XI, Paragraph IHP-3100.
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13310 E-1 10/25/88 HVS-94 i
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1 Georgia lbwer ENCLOSURE (continued)
PLANT V0GTLE RESPONSE TO BULLETIN 88-04 l
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RESPQNSE TO NRCB 88-04 ACTION ITEM 2 l
Based on a Westinghouse analysis, the potential does not exist for the centrifugal charging pumps or the high head safety injection pumps to deadhead because of the distribution of their miniflow line resistances.
Procedures prohibit the operation of both of the containment spray pumps or the boric acid transfer pumps at the same time on miniflow during i
surveillance testing.
However, an operator could mistakenly start both l
boric acid transfer pumps resulting in reduced flow from both pumps; this situation has therefore been considered in the Hestinghouse analyses.
The possibility of a similar error while surveillance testing the containment spray pumps is not considered because of the separate lines provided for surveillance testing.
During accident situations, there is no potential for parallel pump interaction of the containment spray pumps.
NRCB.88-04 ACTION ITEM 3 Evaluate the adequacy of the mintflow bypass lines for safety-related centrifugal pumps with respect to damage resulting from operation and l
testing in the miniflow mode.
This evaluation should include consideration of the effects of cumulative operating hours in the miniflow mode over the lifetime of the plant and during the postulated accident scenario involving I
the most time spent in this mode.
The evaluation shoJld also include I
verification from the pump suppliers that current minif'.ow rates (or any proposed modifications to miniflow systems) are sufficient to ensure that there will be no pump damage from low flow operation.
If the test data do not justify the existing capacity of the bypass lines, the licensee should provide a plan to obtain additional test data and/or modify the miniflow l
capacity as needed.
RESPONSE TO NRCB 88-04 ACTION ITEM 3 A Hestinghouse evaluation of the thermal and mechanical pump miniflow has been completed for all pumps identifled in the response to Action Item 1 except for the AFH pumps.
Ingersoll-Rand expects to furnish the results of the AFH evaluations to GPC by November 15, 1988.
The results of the thermal mintflow evaluation for the remaining pumps indicate that the required miniflow is substantially below the actual miniflow.
That is, the actual miniflow is adequate to prevent pump overheating, cavitation, and potential short term fa11ere.
1331U E-2 10/25/88 HVS-94
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Georgia Power d ENCLOSURE (continued)
EL31_V0GTLE RESPONSE TO BULLETIN 88-04 i
The results of the mechanical miniflow evaluation indicate that the calculated flow is lower than the actual miniflow in each mode of operation.
This indicates that no unusual or accelerated wear is to be expected due to low flow operation for the pumps evaluated. Note that this nominal miniflow is for the intermittent conditions and is not to be interpreted as being asp 11 cable for continuous operation.
The mechanical miniflows represent nom 1nal values which '. sere calculated using state of the art empirical data and analytical modeling.
Nestinghouse believes, as our Nuclear Steam Supply System supplier, that there is sufficient conservatism in these calculational techniques such that a tolerance of 10% could be applied to these flow values without affecting long term pump c?eration.
Additional justification to support the present flows and system configuration include the fact that there is significant margin between the thermal miniflow and the actual flow for each operating mode.
The normal operating time for modes at the lowest flows is approximately 30 minutes; this results in very limited operation at these flows.
The nominal mechanical mintflow wear and aging effects, if present, are long term in nature and are expected to result in gradual wear to the pumps.
The miniflow calculation techniques were discussed with the pump suppliers who found them to be acceptable.
The resulting calculated miniflow values are acceptable to the pump vendors for the operating modes and times identified in the Westinghouse evaluation.
In addition, the Nuclear Plant Reliability Data System and Licensee Event Report databases do not indicated that these pumps are experiencing any frequent or unusual failures which might be attributable to low flow operation.
COMfiUSION Based on the discussion above, the existing pump miniflow configurations and rates were found to be adequate for the centrifugal pumps identified in the response to Action Item 1, with the exception of the AFH pumps, and no changes to plant hardware or operating procedures are indicated.
This obviates Action Item 5 for the evaluated pumps.
Continued operation with the evaluated pump miniflow configurations and rates do not increase the I
probability of occurrence or the consequences of an accident or malfunction l
of equipment important to safety previously evaluated in the FSAR.
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no mechanism for an accident or malfunction, which was not previously evaluated in the FSAR, has been identified.
Further, the current mintflow configurations and rates do not decrease the margin of safety as defined in the basis for any technical specification.
Therefore, continued operation with the evaluated pump miniflow configurations and rates does not represent a potential unreviewed safety question as defined in 10CFR50.59.
13310 E-3 10/25/88 HVS-94
Georgi 1 Power ENCLOSURE (continued)
PLANT V0GTLE RESPONSE T0_ BULLETIN 81-14 Pursuant to the requirements of Action Item 6 of the NRCB, a detailed l
description o,' the methodology used and the results of the thermal and mechanical pump miniflow evaluation for pumps identifled in the response to i
Action Item ) will be maintained onsite for the next two years.
GPC l
.l expects Ingersoll-Rand to furnish the results of the AFH thermal and mechanical pump mintflow evaluations by November 15, 1988.
The preliminary indication is that the existing miniflow is adequate.
Therefore GPC plans I
l to address Action Item 3 for the AFH pumps by December 15, 1988, which will complete the reporting requirements for NRC8 88-04 Action Item 4.
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