ML20086K316

AO 74-48:on 741105,main Steam Line Flow Switch DPIS-2-2-116A Failed to Trip Instantaneously.Caused by Binding within Switch Mechanism.Guide Repositioned & Calibr of Switch Rechecked

ML20086K316
Person / Time
Site:	Peach Bottom
Issue date:	11/15/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-74-48, NUDOCS 8401270024
Download: ML20086K316 (2)

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PHILADELPHIA ELECTRIC COMPANY . W~o\..t~j

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November 15, 1974

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Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, D.C. 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. Walt Baunack, A.E.C. Region 1 Regulatory Operations Office on November 5, 1974.

Written notification was made to Mr. James P. O ' Rei l l y , Region 1 Regulatory Operations Office on November 6, 1974. .a accordance with Section 6.7.2.A of the Technical Specifications, Appendix A of DPR-44

.for Unit 2 Peach Botton Atomic Power Station, the following report is bei ng subtr.i t ted to the Directorate of Licensing as an Abnormal Occurrence:

Reference:

License Number DPR-44, Amendnent Number 1 Technical Specification Tabic 3.2.A Report No.: 50-277-74-48 Report Date: November 15, 1974 Occurrence Date: November 5, 1974 Facility: Peach Botton k:omic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

Failure of Main Steam Line Flow Switch dPIS-2-2 116A to trip instantaneously.

Conditions Prior to Occurrence:

Unit 2 shutdown, cooled down below 212 F, and vented.

8401270024 741115 PDR ADOCK 05000277 S PDR 1131:3 WP 1 dr.Nf ItEGION. 1 ,

Mr. Gianbusso Movember 15, 1974 l Page 2 Description of Occurrence:

During a routine instrument surveillance test, dPIS-2-2-116A was found to have a delayed trip. In order to provide the proper safety action, the trip must be instantaneous.

I Designation of Apparent Cause of Occur.rence:

Binding within the switch mechanism.

Analysis of Occurrence:

The three conpanion switches in the one-of-two-twice logic were operable and fully capable of producing an isolation.

Therefore, this occurrence had minimal safety implications.

Corrective Action:

The guide for the switch actuation magnet was found positioned such that it was rubbing excessively. The guide was re-positioned to relieve the excessive friction and cycled fificen times to prove instantaneous switch actuation. The calibration of the switch was re-checked following the repairs in accordance with the applicable surveillance test.

Failure Data:

A similar occurrence on this type of switch in this service occurred on 9/6/73.

Very truly yours, r/-

b  ;};ffs/

M. . Cooney ,

Ass't Gen 'l St perintendent Generation Division cc: Mr. J. P. O ' Reil l y Director, Region 1 Uni ted States Atomic En? rgy Commission 631 Park Avenue King of Prussia, PA 19406

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