ML20086K924

Telecopy AO 74-28:on 740525,switch DPIS-2-2-118D Failed to Trip Consistently.Caused by Improper as-built Positioning of Mercury Bulb Type Reed Switch.Mercury Bulb Repositioned to Provide Positive & Consistent Operation

ML20086K924
Person / Time
Site:	Peach Bottom
Issue date:	05/28/1974
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086K917	List: ML20086K914 ML20086K924
References
AO-74-28, NUDOCS 8402070078
Download: ML20086K924 (2)

Text

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I d* May 28, 174 Mr. James P. O'Reilly, Director l .. United States Atomic Ibergy Comaimaion b

Directorate of Regulatory Operations y

, 631 Park Avenue j,

King of Prussia, Pennsylvania 19406 i

Subject:

Abnormal Occurrence 24-Hour Notification Confirming my conversation with Mr. A. D. Toth, A.E.C. Region 1 Regulatory l j Operations Office on May 26, 1974. ,

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Reference:

License Number DPR 44, Amendment Number 1 Technical Specification Table 4.2.A l l

l Report No.: 50-277-74-28 l Report Date: May 26, 1974 1 Occurrence Date May 25, 1974 i

I Facility: Peach Bottom Atomic Power Station '

R.D. 1, Delta, Pennsylvania 17314 l

Identification of Occurrence:

l E- Failure of APIS-2-2-ll8D to trip consistently J

Conditions Prior to Occurrence: '

j Plant operating at close to rated power.

i 4 Description of Occurrence:

[! During a functional instrument surveillance test, dPIS-2-2-118D, a

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PCIS Group I input on Main Steam Line High Flow, failed to trip >

consistently. This switch monitors steam flow in the "C" Main Steen Line.

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( Designation of Apparent Cause of Occurrence:

Improper "as built" positioning of the mercury bulb type reed switch  :

! arch that the magnet would not fully pick up the reed consistently.

I When the switch did function, however, it did function at the proper

setpoint.

d Analysis of Occurrence:

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There are no safety implications associated with this occurrence t since its companion switch in a one-of-two-twice logic on the same steam line had just been tested and found fully operable.

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Corrective Action:

The mercury bulb was repositioned to provide positive and consistent operation. The device was recalibrated and tested per t':e calibration

! check type of surveillance test which includes a functional test. On May 27, 1974, the other 15 similar switches were inspected for a afeitar l . problem, and functionally tested with no failuress and no adjusteente necesamry. -

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hilure Data:

A functional failure of a similar switch was reported as an Abnormal  ;$j

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occurrence on september 6, 1973 -4'+

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{l W. T. Ullrich, Superintendent

i. Peach Bottom Atomic Power Station i

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