ML20197H388
| ML20197H388 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 06/06/1984 |
| From: | Gerrets J, Gerrets T LOUISIANA POWER & LIGHT CO. |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 97, W3K84-1337, NUDOCS 8406180404 | |
| Download: ML20197H388 (5) | |
Text
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I OUISIANA P O W E R & L I G H T! P O BOX 6008
- NEW ORLEANS. LOUISIANA 70174 242 ouAnONOe s1nEer
- (504) 366-2345 g
g UTIUTIES SYSTEM June 6, 1984 W3K84-1337 Q-3-A35.07.97
-_V 33@SDWMld' 2
Mr. John T. Collins Regional Administrator, Region IV ddl l }90$
U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012 1
REFERENCE:
- 1) LP&L letter W3K84-0986 dated April 30, 1984
- 2) Telecon C. Hooper (LP&L) and W. Crossman (NRC IV) on May 11, 1984
- 3) Telecon C. Hooper (LP&L) Eric Johnson (NRC IV) on May 25, 1984
Dear Mr. Collins:
SUBJECT:
Waterford SES Unit No. 3 Docket No. 50-382 Significant Construction Deficiency No. 97
" Diesel Generator "B" Turbocharger Failure" Final Report In accordance with the requirements of 10CFR50.55(e), we are hereby providing two copies of the Final Report for Significant Construction Deficiency No. 97,
" Diesel Generator "B" Turbocharger Failtre".
If you have any questions, please advise.
Very truly yours, T. F. Gerrets Corporate Quality Assurance Manager TFG:CNH:VBR Attachment cc: Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C.
20555 (15 copies) 8406180404 840606 DR ADOCK 05000 1 l
r-Mr. John T. Collins June 6, 1984 W3K84-1337 Page 2 cc: Director 0ffice of Management
.Information~and Program Control U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. E. L. Blake Shaw, Pittman, Potts & Trowbridge
'1800 M Street, N.W.
Washington, D.C.
20036 Mr. W. M. Stevenson Monroe & Lemann 1424 Whitney Building New Orleans, Louisiana 70130 Mr.'W. A. Cross 7910 Woodmont Avenue Suite.1200 Bethesda', Maryland 20814
. Records Center Institute of Nuclear Power Operations
-1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 l
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T FINAL REPORT OF SIGNIFICANT CONSTRUCTION DEFICIENCY NO. 97
" DIESEL GENERATOR "B" TURBOCHARGER FAILURE" INTRODUCTION This report is submitted pursuant to 10CFR50.55(e).
It describes failures of components in both Emergency Diesel Generators (EDG). Our first interim report dated January 24, 1984, was subsequently determined to be incorrect in content (e.g. overspeed problem, bearing replacement, jumper wire). This report will correct previously submitted information.
To the best of our knowledge, this problem has not been identified to the USNRC pursuant to 10CFR21.
DESCRIPTION During the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load testing of EDG "B", af ter approximately 30 minutes at full load, the Diesel was shut down following indication of high turbo inlet temperature and high cylinder exhaust temperatures. Subsequently, while running the "B" diesel to troubleshoot the high temperature conditions, a failure of the turbocharger was experienced as indicated by a rapid increase in exhaust temperatures and no turbo discharge preusure.
Contrary to what was indicated in the interim report concerning EDG "B" thrust bearing replacement, the entire turbocharger was replaced and the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test re-run.
Twenty-one hours into the 100% load test the engine was shut down due to high lube oil pump outlet pressure and the lube oil pump outboard bushing overheating. Following replacement of the pump, troubleshooting and subsequent inspection of cylinder liners and pistons revealed that three cylinder liners, and pistons were heavily scored.
The cause of the EDG "B" turbo failure was a result of failure of the turbo thrust bearing. The engine did not automatically shutdown on impending thrust bearing failure as designed. A subsequent inspection of EDG "A" revealed that the thrust bearing was worn beyond tolerance and that the detector was not set at the correct setting.
This finding suggests that the EDG "B" detector setting from Cooper-Bessemer may have also been set improperly.
Contributing factors to the accelerated wear on the thrust bearing was attributed to repeated starts vithout pre-lube, and/or corrosion due to
- exposure of the system to water during the construction phase as well as leaking tubes in the lube oil heat exchangers. The cause of the cylinder liners, piston and piston rings failure is attributed to one or all of the following:
a) Thermal distress from increased exhaust temperatures following turbocharger failure.
Scoring, once begun, bred continued thermal distress b) airborne debris from turbocharger impeller / diffuser damage c) inadequate oil flow due to. partially plugged strainer. The lube oil pump bushing failure is attributed to one or all of the following: a) debris from the scored piston / liners entering the bushing b) heat build up from excessive pump bypass due to partially plugged strainer c) increased load from higher pump discharge pressure due to partially plugged strainer.
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SCD #97 Final Report-Page 2
'The first' interim report erroneously stated that, "During preoperational
' testing of Diesel Generator "B", an unplanned actuation of the overspeed trip was experienced. Troubleshooting traced the cause to a missing jumper wire in the. governor controls and an improper time delay in the generator field (flashing circuit." Upon further. investigation of the overspeed trip problem,
.it was determined that this occurred on EDG "A" and only while starting in the test mode. No actuations of the overspeed trip device were encountered while the engine started in the emergency mode.
The jumper wire existed on EDG "A"
- as a temporary modification under " Woodward Governor" advice to troubleshoot &ng the cause for the trip. The final corrective action for this
. problem is described below.
SAFETY IMPLICATION If left' uncorrected, with the plant'in operation and the loss of offsite power, failure of one or both Diesel Generators could adversely affect the safe operation of the plant since one or both trains of equipment required for-accident mitigation would-be inoperable.
CORRECTIVE ACTION Based upon the information obtained,~ an analysis of the failure modes was
- performed. As a result, the following actions were taken:
1._
All defective / damaged components of the engine were replaced.
2.
The lube oil-filters were replaced _and the strainer cleaned.
3.
The EDC "A" Turbo Thrust bearing was replaced, failure detector was inspected and proper clearances adjusted.
4.
All protective shutdowns"and alarms have been retested including the
. turbocharger. thrust. bearing failure trip.
5.
Pressure indicators _on both sides of the engine lube oil strainer have been installed. DCN-IC-1833 (CIWA-840096) will be_ completed upon arrival and installation of_the differential pressure indicator.-
<6.
EDG "A" governor unit has been replaced and tested. The field flashing timers for both engines have been reset to proper time delays.
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SCD #97 Final Report Page 3 7.
Subsequent inspections of EDG "A"
& "B" thrust bearing clearances found essentially no wear to the bearings since their replacement. The correct turbocharger thrust bearing wear detector settings for each Diesel Generator have also been verified.
In order to prevent recurrence of turbo thrust bearing failures, the thrust bearing and failure detector clearances will be inspected as part of procedure MM-3-015, " Emergency
. Diesel Engine Inspection" every eighteen (18) months.
8.
Leaking tubes in lube oil heat exchangers were re-tolled and pressure tested.
All corrective action is completed. The supporting documentation has been reviewed. Both Diesel Generators have successfully passed the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test and Preoperational Test Procedure SP0-39-001 was completed and approved.
This report is submitted as the Final Report.
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