ML20084F345

AO 250-75-9:on 751119,pressure Switch PS-3-2058 Setpoint Exceeded Max Limit.Caused by Setpoint Drift.Pressure Switch Recalibr & Setpoint Returned to Proper Value

ML20084F345
Person / Time
Site:	Turkey Point
Issue date:	11/28/1975
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AO-250-75-9, NUDOCS 8304210107
Download: ML20084F345 (2)

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• h' November 28, 1975 q [(y% ", PRN-LI-75-5 N m ,

Mr. Norman C. Moseley, Director, Region II Office of Inspect' ion and Enforcement ,,

'U. S. Nuclear Regulatory Commission 230 Peachtree Street, N. W., Suite 818 Atlanta, Georgia 30303

Dear Mr. Moseley:

ABNORMAL OCCURRENCE 250-75-9 TURKEY PO:NT UNIT 3

• DATE OF OCCURRENCE: NOVEMBER 19, 1975 INCORRECT HIGH-HIGH CONTAINMENT ,

PRESSURE SWITCH SETPOINT A. CONDITIONS PRIOR TO OCCURRENCE The Unit 3 reactor was in the refueling shutdown condition.

B. DESCRIPTION OF OCCURRENCE Instrument calibrations were being performed in accordance with Maintenance Procedure 14007.1, entitled " Process Instrumentation and Calibration, Checks and Tests Prior.to .

and During Refueling". On November 19, 1975, it was~found that pressure switch PS-3-2058, which is one of three pressure switches used to sense high-high containment .

pressure, had a setpcint of 35 psig.- This is above the maximum setpoin't of 30 psig specified in Technical.Specifi-cation Table 3.5-4.

C. DESIGNATION OF APPARENT CAUSE OF OCCURRENCE The setpoint of pressure switch PS-3-2058 was out of i specification because of setpoint drift. The cause of the setpoint drift has not been determined.

D. ANALYSIS OF OCCURRENCE-

. Redundant high-high containment pressure channels are pro-vided as a-part of Engineered Safety Features instrumentation.

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Mr. Norman C. Mose' ley, Director, Region II Page Two -

November 28, 1975 Three high-high containment pressure switches are located in

• the cable penetration room, and each has its own pressure sensing connection to containment. Remote alarm and control signals are provided from each skitch. Actuation of two of the three switches will produce a high-high containment pressure signal input into the safeguards actuation logic.* During.

this occurrence, the setpoints of two of the three high-high containment pressure switches were within specification. If

an actual high-high containment pressure had occurred, the appropriate logic signal would have been generated, therefore, the health.and safety of the public were not adversely affected

, by this occurrence.

E. CORRECTIVE ACTION Pressure switch PS-3-2058 was recalibrated and its setpoint returned to the proper value. A similar switch will be tested i

to determine if the setpoint drift can be reproduced. If the I test reveals significant information regarding the cause of the setpoint drift, a supplementary report will be submitted.

F. FAILURE DATA Pressure switch PS-3-2058, S/N 69127, is a Type 6N-AA3-XRR switch manufactured by the Static O-Ring Pressure Switch.

Company. .

There have been no previous Abnormal' Occurrence reports j 1

involving setpoint drift of a high-high containment pressure

switch. ,

1 Very truly yours, i

w- '

! . D. Schmidt

, Vice President

' Power Resources MAS /cpc cc: Jack R. Newman, Esquire i

, Director, Office of Inspection and Enforcement (40)

I Director, Office of Management.Information and Program *

• i Control (3) l l'

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