05000395/LER-1982-062, Forwards LER 82-062/03L-0.Detailed Event Analysis Encl

Forwards LER 82-062/03L-0.Detailed Event Analysis Encl

ML20083M264
Person / Time
Site:	Summer
Issue date:	01/19/1983
From:	Dixon O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20083M267	List: 05000395/LER-1982-062, Forwards LER 82-062/03L-0.Detailed Event Analysis Encl 05000395/LER-1982-062-03, /03L-0:on 821220,seismic Switch YM-1782 Found to Have out-of-tolerance Trip Point on Transverse Sensor. Caused by Setpoint Drift on Horizontal Transverse Sensor. Switch Calibr & Returned to Svc
References
NUDOCS 8302010111
Download: ML20083M264 (2)

LER-1982-062, Forwards LER 82-062/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3951982062R00 - NRC Website

text

SOUTH CAROLINA ELECTRIC & GAS COMPANY POST OFFICE 764 COLUMBIA. SOUTH CAROLINA 29218 c')

O. W. DixON, JR.

Q vict PRESIDENT NUCLEAR OPERArioNS e

n.

• P Mr. James P. O'Reilly, Director 0

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

Atlanta, Georgia 30303

SUBJECT:

Virgil C.

Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Thirty Day Written Report LER 82-062

Dear Mr. O'Reilly:

Please find attached Licensee Event Report #82-062 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 (a) of Technical Specification 3.3.3.3, " Seismic Instrumentation," on December 20, 1982.

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

Very truly yours, l/

WS m

O. W.

ixon, Jr.

CJM:0WD:dwf Attachment ec:

V.

C.

Summer A.

R. Koon T.

C. Nichols, Jr.

G.

D. Moffatt E.

C.

Roberts Site QA

0. 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.

l 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 M. N.

Browne NPCF File CON

'OW 0302010111 830119 PDR ADOCK 05000395 PDR gg AjL./

O

J Mr. James P. O'Reilly LER No.82-062 Page Two January 19, 1983 DETAILED DESCRIPTION OF EVENT On December 20, 1982, with the Plant in Mode 1, the Reactor Build-ing Foundation Mat Triaxial Seismic Switch (YM-1782) was f ound to have an out-of-tolerance trip point on the Transverse Sensor.

The trip point was found to be set at approximately 0.16g instead of the required 0.lg during performance of the Channel Operational Test identified in Technical Specification 3.3.3.3, Table 4.3-4, Item 1.c.

The seismic switch is designed to initiate an alarm upon the recognition of a seismic event yielding a ground acceler-ation greater than or equal to the Operating Base Earthquake (OBE).

PROBABLE CONSEQUENCES There were no adverse consequences from this event.

At the time of discovery of this event, there were other seismic instruments in operation which would have properly recorded earthquakes and provided alarms.

A response spectrum recorder at the same location provides indication and alarm in the Control Room for any earthquakes producing ground motion greater than or equal to the OBE (.lg), while a seismic trigger unit at the same location (set to.0lg horizontal and.00679 vertical) activates two (2) time history accelerographs and produces an audible alarm.

Therefore, instrumentation was available to adequately record seismic events.

Additionally, the seismic switch is a triaxial device capable of acceleration measurement in three (3) orthogonal directions-(one vertical and two horizontal) and initiation of alarms as a function of these measurements.

The Horizontal (Longitudinal) and Vertical Sensors of this seismic switch would have operated.

CAUSE(S) OF THE OCCURRENCE The cause of this occurrence is attributed to setpoint drift on the Horizontal (Transverse) Sensor of Seismic Switch YM-1782.

IMMEDIATE CORRECTIVE ACTIONS TAKFN A calibration of the triaxial seismic switch was performed with the appropriate surveillance test procedure, and the equipment was subsequently returned to service on December 21, 1982.

ACTION TAKEN TO PREVENT RECURRENCE The Licensee plans no additional action in regards to this event other than the normal surveillance testing.

-,m.

w