05000395/LER-1983-003, Forwards LER 83-003/03L-0.Detailed Event Analysis Encl

Forwards LER 83-003/03L-0.Detailed Event Analysis Encl

ML20064M693
Person / Time
Site:	Summer
Issue date:	02/07/1983
From:	Dixon O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20064M697	List: 05000395/LER-1983-003, Forwards LER 83-003/03L-0.Detailed Event Analysis Encl
References
NUDOCS 8302150613
Download: ML20064M693 (3)

LER-2083-003, Forwards LER 83-003/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3952083003R00 - NRC Website

text

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.r SOUTH CAROLINA ELECTRIC & GAS COMPANY Post orrica 7e4 COLUMelA, SOUTH CAROUNA 29218 O. W. DixoN, JR.

susl["o',*,*l"[ .. February 7, 1983 $ E c.c Mr. James P. O'Reilly, Director (C

~~

U.S. Nuclear Regulatory Commission Region II, Suite 3100 101 Marietta Street, N.W.

1. [

Atlanta, Georgia 30303 .

SUBJECT:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Thirty Day Written Report LER 83-003

Dear Mr. O'Reilly:

Please find attached Licensee Event Report #83-003 for Virgil C. Summer Nuclear Station. This Thirty Day Report is required by Technical Specification 6.9.1.13.(b) as a result of entry into Action Statement 6 of Technical Specification 3.3.1,

" Reactor Trip Instrumentation," Item 14, on January 8, 1983, and January 20, 1983.

Should there be any questions, please call us at your convenience.

Very tru y yo rs, O. W. i xoit , r.

HCP:OWD:dwf/fjc Attachment cc: V. C. Summer A. R. Koon T. C. Nichols, Jr. G. D. Moffatt E. C. Roberts Site QA O. W. Dixon, Jr. C. L. Ligon (NSRC)

H. N. Cyrus G. J. Braddick H. T. Babb J. L. Skolds D. A. Nauman J. B. Knotts, Jr.

M. B. Whitaker, Jr. B. A. Bursey W. A. Williams, Jr. I&E (Washington)

O. S. Bradham Document Management Branch R. B. Clary INPO Records Center C. A. Price NPCF File 8302150613 830207 DR ADOCK 05000 g s ,

5: q ggp .g bd? h

• f Mr. James P. O'Reilly i LER No.83-003 Page Two February 7, 1983 DETAILED DESCRIPTION OF EVENT On January 8, 1983, at 0705 hours0.00816 days <br />0.196 hours <br />0.00117 weeks <br />2.682525e-4 months <br />, the Main Control Board indication for Steam Generator "A" feedwater flow (IFI-477) failed low. On January 20, 1983, at 1017 hours0.0118 days <br />0.283 hours <br />0.00168 weeks <br />3.869685e-4 months <br />, IFI-477 indicated approximately 20% below redundant channels. The i plant was operating in Mode 1 at 50% power during these occurrences. The channel was declared inoperable, and its

, associated bistables were placed in the tripped condition within one (1) hour (during both events) in accordance with Technical Specification 3.3.1, Item 14, Action Statement 6.

PROBABLE CONSEQUENCES There were no adverse consequences as a result of the events since the downscale failure of the instrument channel was in the safe direction. A reactor trip would still have occurred with a Steam Generator low water level in coincidence with a steam flow /feedwater flow mismatch.

CAUSE(S) OF THE OCCURRENCE The cause of the two (2) events is as follows:

1. The failure of IFI-477 on January 8, 1983, is attributed to breakdown of the circuit board electronic components when exposed to the internal cabinet temperature.

j 2. The erroneous readings observed on January 20, 1983, is attributed to instrument drift of the circuit board installed on January 8, 1983.

t

Mr. James P. O'Reilly LER No.83-003 Page Three February 7, 1983 IMMEDIATE CORRECTIVE ACTIONS TAKEN On January 8, 1983, the channel for Steam Generator "A" feedwater flow (IFI-477) was placed in the tripped condition within one (1) hour. It was determined that the power supply card (FQY-477) would not function within the temperature parameters present in the instrument cabinet. The circuit board was replaced, and the channel was returned to operable status af ter the performance of a satisfactory channel calibration with the appropriate surveillance test procedure on January 8, 1983, at 1415 hours0.0164 days <br />0.393 hours <br />0.00234 weeks <br />5.384075e-4 months <br />.

Action was initiated to lower instrument cabinet and room temperature to prevent recurrence.

On January 20, 1983, the channel was again placed in the tripped condition within one (1) hour of the observance of the low readings. The output of the power supply card (FQY-477) was found to be out-of-tolerance low upon performance of a channel calibration. The output was calibrated, and the channel was returned to operable status on January 20, 1983, at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, upon successful completion of the appropriate surveillance test procedure.

ACTION TAKEN TO PREVENT RECURRENCE The licensee is implementing a modification to alter the relay room ventilation flow path for the purpose of providing more effective cooling to the instrument cabinets. Testing performed by the licensee indicated that air stagnation existed in the relay room from inadequate HVAC air distribution. A temporary modification has been installed with acceptable results to date.

The permanent modification is expected to be complete by April 15, 1983. This action negates the need to add air conditioning in the Relay Room as discussed in LER 82-016, Revision 2 (January 13, 1983, letter from O. W. Dixon, Jr. to J. P. O'Reilly).

Additionally, for the January 20, 1983 event, the licensee plans to initiate a follow-up investigation to determine the cause of the instrument drift. This is expected to be complete by April 15, 1983.

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