ML20086J315

Telecopy AO 74-16:on 741015,hydraulic Snubbers on Piping Between Valves & Condenser Failed.Caused by Acceleration Amplifiers Out of Calibr.Snubbers Repaired

ML20086J315
Person / Time
Site:	Peach Bottom
Issue date:	10/17/1974
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086J293	List: ML20086J289 ML20086J303 ML20086J315
References
AO-74-16, NUDOCS 8401230568
Download: ML20086J315 (2)

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n7llg i l KG.gg D E l.tu t.tL PHILADELPHIA ELECTRIC COMPANY Peach Ecttom Atomic Power Station

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O b b*ty . C LUJ . Delta, naylvania October 17, 1974 [

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}ir. James P. O'Reilly, Director j United States Atomic Energy Coamission Directorate of Regulatory Operations I

631 Park Avenue King of Prussia, Pennsylvania 19406 Subj ec t : Abnorral Occurrenc_e 24-nour Notification Confirting W. T. Ullrich's phone convernat* ion with Mr. Walt Baunack, A. E.C.

] Region 1 Regulatory Operations Office on October 16, 1974 i _

Reference:

License Number DPR-56 Technical Specification Reference Paragraph 3.11.D

-] Report No.- 50-278-74-16

_ Report Date: October 16, 1974

) Occurrence Date: October 15, 1974 - - - -

Facility: Peach Bottom Atomic Pover Station R.D. 1, Delta, Pennsylvania 17314  %

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Identification of Occurrence: -

Y, ,. 9 Failed hydraulic anubbers on piping betvten bypass valves and condenser.

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Conditions Prior to Occurrence:

Reactor shutdown. Primary systes pressure 100 psig.

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Description of Occurrence: [,u - 7 7 During a routine inspection of the pipe hanger systes following a reactor

% * '8 a ,h shutdown on October 15, 1974, four snubbers on the piping between the bypass  ; j.9 valves and the eain condenser were found to be defective. The snubbar on & . t '-

the #1 bypass valve was physica)ly detached from the piping. The nuts and bolt which hold the eye of the snubber piston to the pipe clacp had 6, -k{.'.':(

vibrated loose. The snubbers on the #2 and #3 bypass lines were conne:ted TV .ic .

to the piping, but the pipe clatp had rotated around tha pipe approxi- ]J.Q{pg mately 1" to 1-1/2". The anubber on the d6 bypass valve was broken at the #

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point where the attaching eye screws into the cod of the snubber piston. #

All other snubbers appeared to bw satisfactory.

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Designation of Apparent Cause of Occurrence:

Out of calibration acceleration a=plifiers in the EHC systes caused bypass 4%

7.i;; y valre fluctuations on the #1, #2 and #3 bypass valves during a esin y.,.(p J :

turbice startup on October 4,1974 and on the $6 bypass valve during a 6 pf turbine overspeed test on October 7, 1974. Cycling of these bypass valves ;fj y) on about a one second interval for ceveral minutes is believed to have E. V .v..

caused the damage noted on the hydraulic anubbers.

8401230568 74102S

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PDR ADOCK 05000278 S PDR -

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Analysis of Occurrence.

It is believed that the cyclic operation of the bypass valve would cause excessive pipe t:otion. An inspection of the piping support syste:s by the piping support designer following the snubber failure did not disclose any additional failurcs. It appears that no piping overstress occurred as a result of this effort. The type ,

of operation experienced is not expected to reoccur. This occurrence, therefore, has minimal saf ety implications.

Corrective Action:

Repairs were made to the four snubbers noted. The pipe cla=ps were tightened and aligned properly. The bolts and nuts were secured such that vibration could not cause loosening. Individual .. .

valves were operated at 150 poig and full pressure during the plant startup on October 16, 1974. The full pressure test was observed by the piping support engineer. Piping supports and pipe snotion were judged proper during thcsc tests.

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Very truly yours, ff/ '

W. T. Ullrich, Superintendent ~-em_;

Pesch Bottom Atomic Power Station. 2

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