ML19312E362
| 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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e 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.
a L
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.
1 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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