05000346/LER-1979-071-03, /03L-0 on 790704:while Performing Valve Lineup for Auxiliary Feedwater Sys Test ST 5071.04,valve AF 3870 Was Discovered to Lack Position Indication at Control Room Switch.Caused by Short in Motor Winding or Single Phasing

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/03L-0 on 790704:while Performing Valve Lineup for Auxiliary Feedwater Sys Test ST 5071.04,valve AF 3870 Was Discovered to Lack Position Indication at Control Room Switch.Caused by Short in Motor Winding or Single Phasing
ML19242B219
Person / Time
Site: Davis Besse 
Issue date: 08/01/1979
From: Naylor R
TOLEDO EDISON CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19242B216 List:
References
LER-79-071-03L, LER-79-71-3L, NUDOCS 7908070692
Download: ML19242B219 (1)


LER-1979-071, /03L-0 on 790704:while Performing Valve Lineup for Auxiliary Feedwater Sys Test ST 5071.04,valve AF 3870 Was Discovered to Lack Position Indication at Control Room Switch.Caused by Short in Motor Winding or Single Phasing
Event date:
Report date:
3461979071R03 - NRC Website

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HE.RT D ATE S3 EVENT DESCRIPTICN AND PROB ABLE CONSECUENCES h l On 7/4/79, while perf ornirg a valve lirleup f or Auxiliary Feudwater System Surveillance l o

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control room switch. An attenpt made at 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br /> to operate the valve electrically l gg lwas unsuccessful.

As the unit was in Mode 5 at the time of this Occurrence, the Actiorl o

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFOIU1ATION FOR LER NP-33-79-78 DATE OF EVENT:

July 4, 1979 FACILITY:

Davis-Desse Unit 1 IDENTIFICATION OF GCCURRENCE:

Failure of motor operator on auxiliary Feed Pump 1-1 Stop Valve AF 3870 co Fream Generator 1-1 Conditions Prior to occurrence: The ur.it was in Mode 5, with Power (MWT) = 0, and Load (Gross MWE) = 0.

Description of Occurrence: On July 4,1979 at 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, operations personnel closed supply breaker BE 1147 for Auxiliary Feedwater Valve AF 3870 wbile performing lineups f or Auxiliary Feedwater System Surveillance Test ST 5071.04.

At 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br />, it was discovered that there was no position indication for AF 3S70 at the Control Room switch. The problem was noted, and the test was continued for Auxiliary Feed-water Train 2.

At 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br />, testing was completed on Auxiliary Feedwater Train 2.

At this time, the operator attet.pted to operate AF 3870 electrically.

The valve would not operate and was declared inoperable.

Technical Specification 3.7.1.2 re-quires two independent steam generator auxiliary feedwater pumps and flowpaths be operable in Modne '

?, and 3.

This report is bei :g submittad as documentation of a component fa ilu re.

Designatien of _ Apparent Cause of Occurrence:

The control circuits for the motor operator for AF 3870 were checked and found operational. The motor was determined to be defective due to low winding resistance, a daruaged winding lead, and the open circuit dirough the overload heaters.

The motor was returned to the vendcr for further analysis.

The analysis by the vendor resul ton in two po un ibl, cm.9 as of this occurrence:

(1) an electrical failure in the notor for AF 3870 from single phasing in the motor caused by damage to a motor lead during installation or main-tenance, or (2) a premature winding failura due to internal shorting.

Although damage was discovered to a winding lead, it could not he deternined by the vendor that this caused the winding failure.

Analysis of Occurren.:e: There was no danger to the health and safety of the public or station perstonel.

The unit was in Mode 5, and the Auxiliary Feedwater Train 2 was ope able a*

the time of the occurrence.

Feedwater Train 1-1 could have been made functional if required by manually operating AF 3870.

Corrective Action

Under Maintenance Work Order 79-2739, the notor, the motor over-load relay, and the overload Featers were replaced. The motor and control circuits were tested per ST 5071.04 and determined operable on July 5,1979.

Failure Data:

Although there have been several previous railures of motor operators, there hrve been no previously reported occurren tes due to motor f ailure.

LER #79-071

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