ML20150E536
| ML20150E536 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 07/08/1988 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-88-004, IEB-88-4, ULNRC-1801, NUDOCS 8807150191 | |
| Download: ML20150E536 (6) | |
Text
g Etscraic-35 1901 Gratiot Street, St. Louis Donald F. Schnell July 8, 1988 Vce President U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-137 Washington, D.C.
20555 ULNRC-1801 Gentlemen:
DOCKET NO. 50-483 CALLAWAY PLANT POTENTIAL SAFETY-RELATED PUMP LOSS
Reference:
NRC Bulletin No. 88-04, dated May 5, 1988 NRC bulletin 88-04 required licensees to investigate and correct safety-related pump losses due to pump minimum flow interactions or inadequately sized pump minimum flow lines.
The attachments to this letter provide the required 60 day response and detail Union Electric's efforts concerning this bulletin.
If you have any questions concerning this information, please contact me.
l Very truly yours, l
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Donald F.
Schnell WEK/ dis Attachments 8807150191 880708 i
I PDR ADOCK 05000483 G
PNV Ma,hng Address: PO. Box 149, St. Lovs MO 63166
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STATE OF MISSOURI').'
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Donald F. Schnell, of lawful age, being first duly sworn-upon--oath says that he is Senior Vice President-Nuclect and an officer of Union Electric. Company; that he has read the foregoing document andEknows the content thereof; that he has executed the same for and on behalf of said-company with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information-and belief.
By D'onald F. Schnell Senior-Vice President Nuclear
-SUBSCRIBED and sworn to before me this 8th day of July 198 8 JOHANNA F. WEG. ANN ElOTARY PUBUC - STATE OF MD.-
Q Ne CALLAWAY COUNTY J h nn F. Wegmanfi r
MY COM#JSSION EXFIRES.
'9ANUARY 29,1990 l
1
.- 6 7c' Gerald Charnoff, Esq.
.cc:
Shaw, Pittman, Potts & Trowbridge 2300 N.
- Street, N.W.
Washington, D.C.
20037-Dr.'J.
O. Cermak CFA, Inc.
-4. Professional Drive (Suite 110)
Gaithersburg,.MD 20879 W. L.
Forney Chief,' Reactor Project Branch 1 U.S.
Nuclear' Regulatory Commission
~
Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137
. Bruce Little Callaway Resident Office U.S.
Nuclear. Regulatory Commission-1 RRil Steedman, Missouri 65077 Tom Alexion. (2)
Of fice of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission Mail Stop 316 7920 Norfolk Avenue Bethesda, MD 20014 Manager, Electric' Department Missouri Public Service Commission P.O. Box 360 Jefferson City, MO 65102 l
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Attachm:nt 1 to ULNRC-1801 NRC BULLETIN 88-04 POTENTIAL SAFETY-kELATED PUMP LOSS NRC Bulletin 88-04 required the evaluation of all safety-re-lated pumps for 1) pump-to-pump interaction during miniflow operation that could result in dead-heading of one or more of the pumpo and 2) the adequacy of the minimum flow bypass lines with respect to damage resulting from operation and testing in the minimum flow mode.
A written response was to be transmitted to the NRC within 60 days of bulletin receipt which a) summarizes the problems and 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 problems identified as a result of this bulletin and, d) provides justification for continued operation.
Union Electric's evaluation to date indicates that the situation in Item 1 above has been greatly minimized at callaway Plant.
Pumps which share a common recirculation line have been equipped with multi-plate restricting orifices which act to desensitize the system when pumps are running in parallel to prevent the weak pump / strong pump effect.
The multi-plate orifices desensitize the system by causing a significant pressure drop to occur before the point where the individual pumps recirculation lines join to form the common recirculation line.
At the common point the fluid pressure has been significantly reduced so that back-pressure imposed on the weak pump's recircu-lation line is low enough to prevent the strong pump from "dead-heading" the weak pump.
Therefore, this is not a concern at Callaway.
Item 2 describes a condition that does exist at Callaway (e.g. several safety-related pumps have installed minimum flow capacities less than that required for continuous operation).
In those cases, the pump manufacturers are being requested to establish limits for the maximum amount of time the pumps are allowed to run on the present installed minimum flow and minimum flow rates required for continuous operation.
Precautions will be placed in affected operations procedures where the present installed minimum flow capacity is less than that required for continuous operation.
The precaution will state that the pump should not be run at the present minimum flow for longer than the time established by the manufacturer unless necessary to fulfill a safety function.
Examples of plant conditions which could require running a pump on minimum flow, or at a flow less than that required for continuous operation, are a small break LOCA where the pressure decays so slowly that the
Attcchtsnt 1 to ULNRC-1801 safety injection and RHR pumps operate at minimum flow for a period of time or plant cooldown with auxiliary feedwater at the beginning of core life where cooldown limits could be violated.
The training department will evaluate incorporating the subject of low flow internal recirculation pump damage in the appropriate courses and all operators and technical personnel will receive training on this subject.
As a final precaution against losing the operability of safety-related pumps due to the effects of low flow operation, all of the affected pumps are tested under the pump and valve operability program.
The pump curve is checked and trended under this program, which is required by ASME code,Section XI, and Section 4.0.5 of the Technical Specifications.
Any degradation of the pum; performance will be identified before the pump is incapable of performing its safety function.
In addition, visual inspection of impellers for damago due to localized cavitation will be performed, as appropriate.
The above details the short term modifications to plant operating procedures which will be implemented within 60 days of the date of this letter.
Long term modifications to plant systems, procedures or training programs and a schedule for implementation will be provided within 180 days of the date of this letter.
At that time, a written report will be transmitted to the NRC which describes all actions taken to resolve the concerns of this bulletin.
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Attachmont'2,to ULNRC-1801 '
List of Pumps. Evaluated Auxiliary.Feedwater Centrifugal Charging-SafetyLInjection-Residual-Heat Removal Boric Acid Transfer Containment Spray Essential Service Water Component Cooling Water Fuel Pool Cooling
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Fuel Oil Transfer BIT Recirc Pump Diesel Generator Jacket ~ Water Diesel-Intercooler Jacket Water Keep-warm i
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