05000219/LER-1983-002, Forwards LER 83-002/03L-0.Detailed Event Analysis Encl

Forwards LER 83-002/03L-0.Detailed Event Analysis Encl

ML20069A716
Person / Time
Site:	Oyster Creek
Issue date:	03/04/1983
From:	Fiedler P GENERAL PUBLIC UTILITIES CORP.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20069A718	List: 05000219/LER-1983-002, Forwards LER 83-002/03L-0.Detailed Event Analysis Encl 05000219/LER-1983-002-03, /03L-0:on 830123,startup Banks Removed from Svc Due to Dilution Plant Main Breaker Cable Termination Failure.Cause Under Investigation.Dilution Pump Power Feed Terminations Replaced
References
NUDOCS 8303160214
Download: ML20069A716 (3)

LER-1983-002, Forwards LER 83-002/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2191983002R00 - NRC Website

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GPU Nuclear NQQIQf P.O. Box 388 Forked River, New Jersey 08731 609-693-6000 Writer's Direct Dial Number:

March 4, 1983 Mr. Ronald C. Haynes, Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

Dear Mr. Haynes:

Subject: Oyster Creek Nuclear Generating Station Docke t No. 50-219 -

Licensee Event Report Reportable Occurrence No. 50-219/83-02/03L This letter forwards three copies of a Licensee Event Report (LER) to report Reportable Occurrence No. 50-219/83-02/03L in compliance with paragraph 6.9.2.b.2 of the Technical Specifications. We realize this LER is being subnitted beyond the time limitation specified in Technical Specifications, paragraph 6.9.2.b.

The cause of the delay is attributed to administrative delay within the department responsible for the investigation of the event described herein and the preparation of this LER.

Very truly yours, Peter B. Fiedler Vice President and Director Oyster Creek PBF:jal Enclosure s 1

1 l

cc: Director (40 copies)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.

20555 I

1 Dire ctor (3) l Of fice of Management Information and l

Program Control U.S. Nuclear Regulatory Commission Washington, D.C.

20555 NRC Resident Inspector Oyster Creek Nuclear Generating Station (d

Forked River, Ni 08731 8303160214 830304 SRADOCK05000

clear is a part of the General Public Utikties System

i OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/83-02/03L Report Date March 4, 1983 Occurrence Date January 23, 1983 Identification of Occurrence Bank 5 (Startup Transformer A) was taken out of service to allow investigation of s

'S actrical fault on the dilution-plant power feed. This condition ce es operation in a degraded mode permitted by a limiting condition for og

- on as specified in the Technical Specifications, paragraph 3.7.B.

This event is considered a reportable occurrence as defined in Technical Specifications, paragraph 6.9.2.b.2.

Conditions Prior to Occurrence The reactor was operating at steady state with the mode switch in RUN.

Power :

Reactor 955 MWt Genera tor 245 MWe Description of Occurrence At 10:44 a.m. on January 23, 1983 Thermal Dilution Pumps 2 and 3 tripped due to a trip of the dilution pumps' main breaker.- It was discovered that the dilution plant cabling high voltage terminations (stress cones) had failed.

The terminations were located on the load side of the dilution plant main 4160V breaker which draws power f rom a connection to Bank 5 startup transformer (of fsite power). Startup Bank 5 was taken out of service to investigate and test for damage to the transformer or degradation of the cable on the secondary side of Bank 5.

Apparent Cause of Occurrence The cause of the occurrence is attributed to the failure of the dilution plant power feed terminations. Bank 5 (Startup Transformer A), was removed from

~

service, as a precautionary measure, to ascertain if the cable termination fault had caused damage to the startup bank cables or equipment, which could lead to further failures, and alleviate danger to work crews replacing the i

failed terminations.

• (

Licensee Event Report Page 2 Reportable Occurrerce No. 50-219/83-02/03L The. power feed to the dilution plant is composed of 5KV shielded cable and heat shrink stress cones terminated at an outdoor GE 4.16 AM 250 Magneblast circuit bre aker. The visual indications observed following the fault showed the origin of failure at the' shield to stress cone interface (the area of highest electric field stress). Further, the fault progressed from inside the cable to the external surface indicating an internal failure of the stress cone due to corona (high field stress).. Additional support for a failure due to corona was the time frame between cable installation to cable failure, which was approximately 3 years:

the approximate time for new SKV cable to degrade when excessive corona is present.

At-the present time it has not been concluded whether the presence of corona in the cable termination was due to construction error or misapplication, although the design was reviewed and appears consistent with the manufacturer's recommendation.

Analysis of Occurrence Startup Bank 5 via startup breaker S1A supplies power to the 1A 4160 bus in the event normal power cannot be supplied by the main generator via the station auxiliary transformer through the 1A main breaker.

The safety significance of this event is considered minimal for the following reason:

During the time that Bank 5 was out of service, had the 1A 4160 bus lost power from the auxiliary transformer, all emergency loads on the IC bus, which is normally powered by the IA-bus, would have been supplied by Emergency Diesel Generator No.1 which remained in operational condition throughout the entire 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> period that Bank 5 was taken out of service.

Corrective Action

Startup Bank 5 and its associated cables were satisfactorily neggered and returned to service. The dilution pump power feed terminations were replaced and the dilution pumps were returned to service on January 30, 1983.

As of this date it has not been determined if the installation of the terminations or the material itself was the cause of failure. Although it is not believed f rom visual evidence that cable or termination design was deficient, the failed sections have been rete.ined and will be sent to the termination manufacturer for evaluation.

Additional high potential testing will be performed during the current refueling outage to further quantify the integrity of the cable terminations in the affected system.

- Failure Data Manufacturer: Ray Chem High Voltage Termination HVT-0-A-1-00 Anaconda 5 KV Unishield Power Cable d

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