ML19312E362

Final Deficiency Rept Re Incorrect Current Sensor in 480- Volt Load Ctr Circuit breaker.Safety-related 480-volt Breakers Inspected Visually.One Sensor Replaced.Manufacturer Notified

ML19312E362
Person / Time
Site:	Summer
Issue date:	05/28/1980
From:	Crews E, Wactor J SOUTH CAROLINA ELECTRIC & GAS CO.
To:
References
NUDOCS 8006040304
Download: ML19312E362 (3)

Text

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' />4 f Sourn CAROLINA ELECTRIC a gas COMPANY nost orrece son re.

Cotune:A, south CAnouMA 29288 E.H. C a rw s, J n.

vice-Petseesat ano Gnove Cascums c...ir.. . o ca sv.uce May 28, 1980 Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission Region II, Suite 3100 101 Marietta Street Atlanta, Georgia 30305

Subject:

Virgil C. Summer Nuclear Station Reportable Substantial Safety Hazard Incorrect Current Sensor in Circuit Breakers - Nuc. Eng. File 3.1051

Dear Mr. O'Reilly:

On 4/30/80, a substantial safety hazard, as defined by 10CFR21, was reported to NRC resident inspector Jack Skolds on an incorrect current sen-sor in a 480 volt load center circuit breaker. The safety hazard is being l

reported under our 10CFR50.55(e) procedure. Detailed information is on the attachment. This is onsidfred the final report on the matter.

f 1 .

e tmly yo s E. H. n ews, Jr.

JAW:EHC:rh ,

cc: H. T. Babb .

E. H. Crews, Jr.

O. S. Bradham D. R. Moore IL Radin J. Skolds V. C. Summer NPCF/Dixon -

File Document Mana gement 3 ranch

/ Washington,.). C.

8006040 3o j

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10CFR21 - SUBSTANTIAL SAFEIT HAZARD

1. Namo_and Address of Reporting Individual James A. Wactor South Carolina Electric & Gas Company

_P. O. Box 764, Columbia, S. C. 29218

2. Identification of Basic Component 480 Volt Load Centers

3. Identification of Firm Supplying Component L

Gould-Brown Beveri i f

4. Nature of Defect, Substantial Safety Hazard Created, and Evaluation Circuit breakers in the 480 volt load centers are equipped with solid state over-5 current devices. Current signals are provided to these devices from current sensors in each phase of the breaker. After finding a wrong sensor in a non-safety related breaker, an inspection of the safety related load centers was initiated. The feeder breaker for mot,or control cent _er XMC-lL 31X-ES_ ijn load center XSW-lEB1 was found to have a current sensor for a 225" amp breaker instead of the 600 amp sensor it should have had.

With this incorrect sensor, the breaker would have tripped at approximately 37.5% of the full load setting (the ratio of 225 to 600). Therefore the motor control center could trip with less than normal load. The service water pump B train discharge valves are fed from this motor control center, so loss of the center would result in loss of the B train service water pump and subsequently loss of B train emergency cooling water. Therefore a substantial safety hazard could be created.

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5. Date Information of Defect Was Obtained - April 9, 1980

6. Number and Location of Defect One incorrect current sensor was found in load center XSW-lEB1, in the feeder breaker to motor control center XMC-lEBlX.

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7. Corrective Action The safety related 480 volt breakers have been inspected visually. The one incorrect current sensor has been replaced. The manufacturer has been notified concerning the problem.

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) 8. Advice to Purchasers or Licensees l

Since normal testing of the solid state overcurrsnt devices dill not reveal this i

problem, it is recommended that a visual inspection be made to insure the correct sensors are installed.

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