ML20086J372

AO 74-12:on 741004,setpoint Drift on RCIC Turbine High Reactor Water Level Sensor Found in Direction Less Conservative than Specified in Tech Specs.Caused by Binding of Wheel on Cam Follower.Cam Follower Assembly Replaced

ML20086J372
Person / Time
Site:	Peach Bottom
Issue date:	10/14/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086J376	List: ML20086J372 ML20086J381
References
AO-74-12, NUDOCS 8401230616
Download: ML20086J372 (2)

Text

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PHILADELPHIA ELECTRIC COMPANY  ; g.

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October 14, 1974 b'

% b #yfky' Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Cormiission Directorate of Licensing Washington, DC 20545 '

Subject:

Abnormal Occurrence i

The following occurrence was reported to Mr. Walt Bounack, A.E.C. Region 1 Regulatory Operations Office on October 4,1974.

Written notification was made to Mr. James P. O'Reilly, Region I Regu- 3 latory Operations Office on October 7,1974. In accordance with Section 6.7.2.A of the Technical Specifications, Appendix A of OPR-56 for Unit 3 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence:

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Reference:

License Number DPR-56 Technical Specification Reference Table 3 2.B j

Report No.: 50-278-74-12 e

Report Date: October 14, 1974 i Occurrence Date: October 4,1974 Facility:

Peach Bottom Atomic Power Station

[d R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

1 sensor Setpoint drif t on the RCIC turbine high reactor water level .%

k in a direction less conservative than specified in the Technical Speci ficati ons.

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Conditions Prior to Occurrence: n 200 ps i .

Unit 3 Start-Up, reactor critical, reactor pressure less than k

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Mr. A. Giambusso p .

October 14, 1974 V p) g_,age 2 Description of Occurrence:

During.a routine instrument calibration surveillance test, the setpoint of one of the RCIC turbine high reactor water level sensors, LIS-3-2-3-101A, was found to have drifted outside the limit called for in the Technical Specifications. The prescribed setpoint for this de-vice is145". The device was found to trip at 45.1".

Designation of Apparent Cause of Occurrence:

The wheel on the cam follower was found to be binding, requir-ing greater motion on the cam to trip the switch.

Analysis of Occurrence:

Since the setpoint was minor, and would not have prevented the ,

sensor from providing a high level signal to the RCIC turbine trip logic, this occurrence has minimal safety implications.

• Corrective Action:

The cam follower assembly was replaced; setpoint adjusted and checked for repeatability; and the instrument functionally checked per the applicable surveillance test prior to returning it to service.  ;

L Failure Data:

These dif ferential pressure switches have required frequent recalibrations to correct setpoint shifts. Since the start-up of Unit 2, setpoint shif ts cn the instruments in this service have required re-calibration on 24 occasions. Shif ts to values in excess of Technical er Specification limits occurred six tines including this occurrence. - Most of these deviations were only slightly beyond the' required setpoints and did not cons.titute a safety hazard.

Very truly yours,

/

. J. Cooney s

.A 't Gen't Superintendent d Generation Division cc: Mr. J. P. O'Reilly Director, Region 1 United States Atomic Energy ' Commission King of Prussia, PA

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