ML20084F437
| ML20084F437 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 10/03/1975 |
| From: | Schmidt A FLORIDA POWER & LIGHT CO. |
| To: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| AO-250-75-7, NUDOCS 8304210131 | |
| Download: ML20084F437 (2) | |
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FLontDA POWER & LIGHT CU.*.*PAMf.
October 3, 1975 1
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Mi. Norman C. Moseley, Director, Region II
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,U.S. Nuclear Regulatory Commission
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Atlanta, Georgia 30303 M~
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,o De'ar Mr. Moseley:
ABNOINAL OCCURRENCE 250-75-7
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.IURKEY POINT UNIT 3
.' DATE OF OCCURRENCE:'SEPTDIBER 24, 1975
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1%LFUNCTION OF HIGH PRESSURE' CGIPARATOR IN L
- PRESSURIZER PRESSURE PROTECTION SYST91 CHANNEL III A..
CONDITIONS PRIOR TO OCCURRENCE
'Ihe reactor was in steady state power operation at 99% rated power.
Pressurizer Pressure Protection System Channel III was in the tripped mode and a functional test of that channel was being perfomed per Operating Procedure 14004.4 entitled " PRESSURIZER PRESSURE AND WATER
. LEVEL PROTECTION CHANNELS Periodic Test."
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DESCRI1/rION'0F OCCURRENCE l
The periodic test was initiated at about 2:40 A\\1 on September 24,'1975.
At about 3:30 N1, the test signal input did not trip the Channel III high pressurizer pressure comparator PC-3-457A at the required setpoint.
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.C. DESIGNATION OF APPARENT CAUSE OF OCCURRENCE
. Tests of the comparator revealed two failed capacitors in the d.c. power supply._: Failure.of these capacitors permitted an a.c. signal to be superimposed on the d.c. signal.in the comparator.
This caused the ccT.parator trip.setpoint_.to bc.raisecl...above the required value.
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ANALYSIS OF OCCURRENCC a.
There are three channels of high pressurizer pressure protection.
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Pressurizer Pressure Protection System logic requires that two of the three channels be in the trip mode in order to produce a reactor trip signal.
During this periodic test, Channels I and II were verified operabic. Had an actual high pressurizer pressure occurred, a reactor trip signal would have been generated at the proper setpoint, there-fore, the health and safety of the public were not.affected by this i
occurrence.
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October 3, 1975 Page Two E.
CORRECTIVE ACTION Comparator PC-3-457A was replaced with a' spare comparator. The PRESSURIZER PRESSURE A\\.I) NATER LEVEL PROTECTION CHANNELS Periodic Test was then satisfactorily completed at about 4:25 Ah! on September 24,.
1975.
Correspondence with the vendor has been initiated to further evaluate the malfunction.
F.
FAILURE DATA The faulty PC-3-457A comparator was >!odel No. 4111082-001, S/N A0 564, manufactured by the Hagan/ Computer Systems Division of Westinghouse.
htalfunction of this Stodel No. comparator occurred on one other occasion.
It was described in Abnormal Occurrence Report 251-75-3.
A. D.
INfkt Vice President Power Resources h!AS/ jar cc: Jack R. Newman, Esquire ice of >!anagement Infomation and Pro Director, gice of Inspection and Enforcement (40 am Control (3)
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