05000296/LER-1981-052-03, LPCI Motor Generator Set 3EA Alternate Feed for 480-volt Reactor MOV Board 3E Removed to Repair Unstable Voltage Regulator.Caused by Feedback Capacitor C8 Failure

LPCI Motor Generator Set 3EA Alternate Feed for 480-volt Reactor MOV Board 3E Removed to Repair Unstable Voltage Regulator.Caused by Feedback Capacitor C8 Failure

ML20027B748
Person / Time
Site:	Browns Ferry
Issue date:	09/27/1982
From:	Christopher W TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20027B744	List: 05000296/LER-1981-052, Forwards Updated LER 81-052/03X-1 05000296/LER-1981-052-03, LPCI Motor Generator Set 3EA Alternate Feed for 480-volt Reactor MOV Board 3E Removed to Repair Unstable Voltage Regulator.Caused by Feedback Capacitor C8 Failure
References
LER-81-052-03X-01, LER-81-52-3X-1, NUDOCS 8209300055
Download: ML20027B748 (2)

LER-1981-052, LPCI Motor Generator Set 3EA Alternate Feed for 480-volt Reactor MOV Board 3E Removed to Repair Unstable Voltage Regulator.Caused by Feedback Capacitor C8 Failure

Event date:
Report date:
2961981052R03 - NRC Website

text

NRC FCRM 366 U. S. NUCLEAR REGULATORY COMMISSION UP,DATE REPORT w

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60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT OESCRIPTION AND PROBABLE CONSEQUENCES h IO I2l l During normal operation. LPCT MC set 3EA. alternate feed for 480V roncenr l

10 l 3 l l MOV Board 3E, was removed from service to repair its ufistable voltace reculator.

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3 35 36 37 40 di 42 43 44 47 CAUSE DES'CRIPTION AND CORRECTIVE ACTIONS h l t l o l lFeedback capacitor C8 failed causine the nenerator volence to swinc about 5 en in l

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Basler Electric tvne KR4F. model P/N-4-1161-100 volenen roeninent m I

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Tennessee Valley Authority Form BF 17 -

Browns Ferry Nuclear Plant BF 15.2 2/17/82 LER SUPPLEMENTAL INFORMATION t'

BFRO 296 / R105p R1 Technical Specification Involved 3 9_n_11 l

Reported Under Technical Specification 6_7_9 h. (p)* Date Due NRC 1

Event Narrative:

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Unit 1 was in a refueling outage; unit 2 was operating at 99-percent power; unit 3 was operating at.97-peroent power.

Units 1 and 2 were not affected by this event. During routine check, the generator voltage was observed to swing about 5 to 10 volts frcm nominal. The 3EA LPCI MG set was removed i

from service and the Basler Electric Company type KR4F' model P/N-9-1161-100 voltage regulator was replaced.- There was no effect on public health and safety. All other unit 3 LPCI FG sets were operable and LPCI MG set 3EA was returned to service within the time limits specified by Technical Specification 3.9.B.11.

There had been two previous similar failures which were not reportable because of equipment status at time of the failures.

The three defective voltage regulators were returned to Basler Ele'ctric Company for failure analysis. Their analysis showed that all three failures were caused by failure of feedback capacitor C8. Basler Electric stated, in a letter dated May 4, 1982, that their records do not reveal recurring failures of this type. During a telecon between Louis Allis, supplier of MG sets, and TVA on December 4, 1981, Louis Allis stated that the failure of capacitor C8 would manifest itself in an output voltage l

variaticn most apparent at low-or no-load operation and generator output would not be significantly affected. Thus this type failure would not make the PG set inoperable. Also in the past 11 months.there have been no more capacitor failures in the eight regulators now in service.

It is concluded from the above evaluations and operating experience that this failure is not a significant generic equipment problem. Therefore, no further f

recurrence control is required.-

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