ML20136G185

Special Rept Spr 85-019:on 851202,malfunction of Train a ESF Load Sequencer Occurred During Surveillance Testing.Testing of Sequencer,W/Outputs Disconnected & Reconnected,Identified Noise Problem.Addl Filtering Network Added

ML20136G185
Person / Time
Site:	Summer
Issue date:	12/27/1985
From:	Nauman D SOUTH CAROLINA ELECTRIC & GAS CO.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
SPR-85-019, SPR-85-19, NUDOCS 8601080043
Download: ML20136G185 (2)

Text

e l

South C:rolina Electric & Gas Company Dan A. Nauman P.O Box 764 V(e President i 4 Colamtx4. SC 29218 thelear Operations l 9 (803) 748 35t3

{

'SCE&G '

December 27, 1985 (n f a

M f Dr. J. Nelson Grace {,

Regional Administrator 5:2 U.S. Nuclear Regulatory Commission l

Suite 2900 101 Marietta Street, NW 2 Atlanta, Georgia 30323 4 en

SUBJECT:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. N P F- 12 Special Report (SPR 85-019)

Dear Dr. Grace:

Attached is a Spec ial Report for th.i Virgil C. Summer Nuclear Station. This is a vo lu n t a r y report submitted at the request of the NRC Re s id en t Inspector.

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

ily yours,

\

h

' O. A. Nauman RMF: DAN /dwf Attachment c: V. C. Summer R. A. S t ou gh

0. W. Dixon, Jr./T. C. Nichols, Jr. G. O. Pe rc iva l E. H. Crews, Jr. R. L. Prevatte E. C. Roberts J. B. Knotts, Jr.

W. A. Williams, Jr. S. D. Hogge Group Managers  !&E Washington O. S. Bradham Document Management C. A. Pr ic e Branch S. R. Hunt INPO Records Center C. L. Ligon (NSRC) ANI Library I K. E. Nodland NPCF File j i

i 8601000043 851227 gDR ADOCM 05000395 m

$ * +I I; W

s Dr. J. Nelson Grace SPR 85-019  ;

Page Two '

December 27, 1985 l

l On December 2, 1985 at approximately 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br />, a malfunction of the train "A" Engineered Sa fe t y Features (ESF) Load Sequencer occurred during surveillance testing. The plant was in Mode 5

( Co ld Shutdown) during the performance of surveillance test procedure (STP-125.010), "In tegrat ed Sa f eguards Test 'A' Train."

The Licensee identified the ma l fu nc t ion to be a resett ing o f the sequencer during the load ing steps prior to completion of the loading sequence. The Train "A" sequencer and diesel generator were declared inoperable and the required boration flow path was shifted to Train "B".

The Licensee's Instrumentation and Control personnel tested the sequencer in an e f fort to determine the source of the ma l func t ion.

A number of tests were success fully comple ted with the s eq ue n c e r i outputs disconnected. However, pr ob le ms with the inadvertent reset [

c ont inued when the sequencer ou t put s were reconnected. '

Troubleshooting continued for approximately four days involving f tests and investigations by the Licensee's Maintenance Engineering i and Nuclear Engineering personnel along with vendor l representatives.

The investigations id e n t i f ied a noise problem which was affecting the reset circuitry. The investigation did not identify the source of the noise. Vendor representatives suggested a modification to pr ov id e an additional f il t e r ing network of capacitors to eliminate the adverse effects of the noise problem.

The modification was completed and the system was success fully t tested and returned to oper ab le status on December 6, 1985.

[

A retest was pe r f o r med on Train "B" to assure that no similar [

problem existed. A total of six tests were performed on Train "B" d u r in g the recent te f ue llng outage. All six tests invo lve d sequencer actuations and were success fu 11y completed withou t 1 e xc e p t ion ; there fore, no modification was warranted for Train "B". !

In addition, an ac tual Sa f et y Injection occurred on December 25, ,

1985 during which both Train "A" and Train "B" sequencers ,

f u nc t ioned properly. The modification to Train "A" and subsequent challenge to the Engineered Sa fet y Fea t ure s System provide assurance that the sequencers can perform their intended finction when required.

The Licensee's sequencers were manufactured by Automation Industries, Inc. (Vitro Laboratories Division) Mode l Numbe r ES FLS Serial Numbers 001 and 002.

i I

I