L-90-287, Corrected Rev 1 to Special Rept:On 900527,discovered That nonsafety-related Standby Feedwater Pumps Unavailable for Plant.Caused by Failure of Valve Stem Bushing Resulting from Overstress of Bushing.Replacement Bushing Mfg Onsite
| ML17348A545 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 08/29/1990 |
| From: | Harris K FLORIDA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| L-90-287, NUDOCS 9009140120 | |
| Download: ML17348A545 (11) | |
Text
ACCELERATED DISTRIBUTION DEMONSTRATION SYSTEM REGULATOR~~
NFORMATION DISTRIBUTION ~TEM (RIDS)
ACCESSION NBR:9009140120 DOC.DATE: 90/08/29 NOTARIZED: NO DOCKET ¹ FACIL:50-250 Turkey Point Plant, Unit 3, Florida Power and Light C 05000250 AUTH.NAME AUTHOR AFFILIATION HARRIS,K.N.
Florida Power a Light Co.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Corrected Rev 1 to special rept:on 900527,nonsafety-related standby feedwater pumps unavailable.
DISTRIBUTION CODE:
IE22D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.
NOTES:
RECIPIENT ID CODE/NAME PD2-2 LA EDISON,G INTERNAL: ACNW AEOD/DSP/TPAB NRR/DET/ECMB 9H NRR/DLPQ/LHFB11 NRR/DOEA/OEABll NRR/DST/SELB 8D NRR/DST SPLB8D1
~REG
'~~~0'GN2 FILE 01 COPIES LTTR ENCL 1
1 1
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1 RECIPIENT ID CODE/NAME PD2-2 PD 1
AEOD/DOA AEOD/ROAB/DSP NRR/DET/EMEB9H3 NRR/DLPQ/LPEB10 NRR/DREP/PRPB11 NRR/DST/SICB 7E NRR/DST/SRXB 8E RES/DSIR/EIB COPIES LTTR ENCL 1
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1 EXTERNAL: EG6rG BRYCE,J.H NRC PDR NSIC MURPHYgG.A 3
3 1
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1 L ST LOBBY WARD NSIC MAYSiG NUDOCS FULL TXT 1
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1 NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM PI-37 (EXT. 20079) TO ELIMINATEYOUR NAMEFROM DISTRIBUTION LISIS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 31 ENCL 31
@PL C'Orated]~d P()
F 0 Box 029100. Miami. F L. 33102 9100 AUG 2 9
$990 L-90-287 U.
S. Nuclear Regulatory Commis s ion Attn:
Document Control Desk Washington, D.
C.
20555 Gentlemen:
Re:
Turkey Point Unit 3
Docket No. 50-250 Unit 3 Standby Feedwater Pumps Unavailability, Revision 1 to S ecial Re ort Technical Specification 3.20.1 Action 2.b)
On May 27, 1990, at 1300 EDT, Florida Power
& Light discovered that both non-safety related standby feedwater pumps were unavailable for Turkey Point Unit 3.
In accordance with the requirements of Technical Specification (TS) 3.20.1, Standby Feedwater System" and TS 6.9.3.j.,
a Special Report, FPL letter 90-206 was issued on June 19, 1990, to describe the failure and corrective actions taken.
The attached report is revision 1 to that Special Report.
This revision provides additional information on
- cause, design requirements, and the maintenance history of the valve and bushing that failed.
Should you have any questions please contact us.
Very truly yours, K. N; Harris vice )resident Turkey Point Plant Nuclear KNH/DRP/DPS/ds attachment
<<>> e~/
C.'
cc:
Stewart D. Ebneter, Regional Administrator, Region II, USNRC Senio'r Resident Inspector,
PNU pip2.
Please note that due to an administrative error this letter was sent out with an error in Attachment 1
(3)
B.
Please replace your file copy of L-90-287 with the.attached complete letter and attachments.
We apologize for any inconvenience we may have caused you.
Thank you very much.
ATTACHMENT 1 Event
Description:
On May 27, 1990, at 1300 EDT, with Unit 3 in Mode 2 (Start-up) at zero
- power, Florida Power
& Light (FPL) discovered that both standby feedwater pumps were unavailable for Turkey Point Unit 3 using the normal path (see discussion of optional paths in section
- 4).
This condition was discovered while aligning the standby feedwater pumps to supply feedwater to the steam generators.
Valve DWDS-3-012 (a non-safety related commercial grade valve) could not be opened.
Since this valve is in the common discharge header to Unit 3 for the standby feedwater
- pumps, both pumps were unavailable to Unit 3
~
However, both pumps were available to Unit 4.
The standby feedwater pumps were to be used while 3A steam generator feedwater pump (SGFP) was out of service for maintenance.
Cause:
Mechanical failure of a valve stem bushing on valve DWDS-3-012 (a non-safety related commercial grade valve) made the valve handwheel inoperable.
Examination of the failed bushing indicated the failure was caused by over-stress of the bushing.
There was no indication of embrittlement or other aging factors, manufacturing flaws, or other potential causes for th'is failure.
The over-stress condition is believed to be the result of the use of a valve wrench during this operation (or a previous operation) of the valve.
Corrective Actions:
A.
Immediate Corrective Actions Immediate attempts were made to locate a replacement for the failed bushing.
When a replacement could riot readily be obtained; a replacement bushing was manufactured on-
- site, approved as acceptable by engineering, and installed.
Valve DWDS-3-012 was successfully test operated and on May 31,
- 1990, at 1930
- EDT, was declared operable.
B.
Generic Concern Review An review of plant records was made to locate other installed valves of this type.
A sample of other valves of this type would have-'~either been disassembled for inspection of their bushings or would have been test operated, if plant operating conditions permitted, to determine if the bushing failure was a generic concern.
A review of plant records showed this valve to be the only one of this type installed at Turkey Point.
A review of the maintenance records indicated no previous failures of this valve or this bushing.
A review of the maintenance records of other similar valves used in non-safety related systems indicate that this type of bushing does occasionally fail (one or two on site failures per year)
C.
Maintenance and Surveillances This valve is tested every refueling outage in accordance with procedure O-OSP-074.4, "Standby Steam Generator Feedwater Pumps/Cranking Diesels Test." If any problems are observed during the operation of the valve, action is initiated to correct the problem.
The standby feedwater pumps are test operated on a monthly basis in accordance with procedure O-OSP-074.3, "Standby Steam Generator Feedwater Pumps Availability Test."
Additionally, the standby steam generator feedwater pumps and flowpath are
- used, per procedure, for routine heatup and cooldown of the units.
D.
Replacement Parts/Valves Spare bushings as well as material identical to the original bushings, in case they need to be fabricated
- again, have been ordered.
Additionally, if DWDS-3-012 fails, spare valves identical to DWDS-4-012 (in the same position in Unit 4) are available for a'otal valve replacement.
E.
Operator Training Plant Operations personnel have been notified of the problems associated with DWDS-3-012 and instructed on recommended acti'ons to take when manual valves do not operate freely.
This instruction includes precautions on the use of valve wrenches.
4.
Analysis of Event:
A.
Standby Feedwater System The Standby Feedwater System is not automatically initiated and requires operator action to be used.
Although the system was installed and is used as a source of feedwater during normal startup, it could provide an additional source of water during accident mitigation for decay heat removal if loss of the'afety related auxiliary feedwater sourepp should occur.
Redundancy The failure of valve DWDS-3-012 does not prevent feedwater flow to the Unit 3 steam generators from the standby feedwater system.
The Unit 3 steam generators can be fed from multiple flowpaths to provide redundancy to assure feedwater to the Unit 3 steam generators in the event main feedwater is unavailable and DNDS-3-012 is shut and can not be opened.
These include the following:
1.
- pumps, 2.
Standby steam generator feedwater pumps if Unit 4
is not operating, (via DNDS-4-012; 4-514, 4-515, or 4-516; 4-20-510; 3-20-510; and 3-514, 3-515, or 3-516),
3.
Turkey Point Unit 2 feedwater pumps via 3-20-510, 4.
Turkey Point Unit 4 main feedwater pumps via 4 510 and 3-20-510, and 5.
Condensate pumps at lower steam generator pressures (upon RCS cooldown and depressurization)
Design Adequacy A review was conducted of the Standby Feedwater System modification package and the design description in the NRC Safety Evaluation provided with Amendment Number 118 to Facility License Number DPR-31 and Amendment 112 to Facility Operating License Number DPR-41.
The review determined that the current Standby Feedwater System is installed as described in the Safety Evaluation.
Main Feed Reg Bypass Header 4-514 A
S/G 4-515 4-516 S/G Unit 4
P82A Normal Feed Unit 4 DWDS-4-012 4-510 F/W From Units1 & 2
)) 3-510 A
S/G Steam Aux Feedwater B
S/G C
S/G S/B Feedwater P82B DWDS-3-012 l
Onit 3
3-514 3-515'-516 1
Normal Feed I
Unit 3 Sketch I j.
I lt
(