ML20024D233
| ML20024D233 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 07/05/1983 |
| From: | Fleischmann R PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 8308030348 | |
| Download: ML20024D233 (1) | |
Text
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i PEACH BOTTOM ATOMIC POWER STATION-Delta, Pennsylvania 17314 4
j July 5, 1983
~
Dr. Thomas E. Murley, Administrator j
_U.
S. Nuclear Regulatory Commission Region I
'631 Park' Avenue
-King of Prussia, Pennsylvania 19406
SUBJECT:
FOLLOW-UP REPORT FOR SEISMIC MONITORING INSTRUMENTATION I
i
. TECHNICAL SPECIFTCATION 3.15R and 6.9.3 l-
REFERENCE:
t,'
Dear Dr. Murley:
As reported in a previous letter, the Response Spectrum Analyzer (RSA),
a component of the seismic monitoring system, has been experiencing intermittent operability problems. Several attempts that included both on and off-site vendor technical support.were made before the problem was finally resolved.
j APPARENT CAUSE:
[
A series of tests were performed to isolate and identify the source of the problem. One test involved removing the 'AC Auxiliary Relays. The only function of these relays was to provide control room annunciation.
1 i
i During the time.the relays were removed, the RSA did not fail. 'Further investigation determined that the AC Auxiliary Relays, cables, and fuses
.had been causing induced noise on the DC signal lines of the seismic b
instrumentation..The induced noise caused voltage spikes in the DC current, i
_ which disrupted integrated circuits and resulted in.the intermittent operation.
4 CORRECTIVE ACTION:
To resolve the problem, the AC Auxiliary Relays, and fuses were removed.
The annunciators in the control room now use DC-power relays located in 4'
the Seismic Warning Panel, a component of the system.
The system has been tested numerous times since the modification'was completed and has performed satisfactorily.
Sincerely, 7
i 8300030348 830705 PDR ADOCK 05000277 l
S PDR_
i R. S. Fleischmann Station Superintendent
)
l RSF:waf cc:
R. C. Stott qf S. J. Kovacs S. A. Spitko File 1
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