ML20086J131

AO 74-37:on 741216,torus High Water Level Switch LS-3-23-91A Failed to Operate.Caused by Switch Assembly Flapper Arm Slightly Restricted by Switch Case.Float/Shunt Assembly Dismantled.Switch Cycled & Rechecked

ML20086J131
Person / Time
Site:	Peach Bottom
Issue date:	12/26/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086J134	List: ML20086J131 ML20086J136
References
AO-74-37, NUDOCS 8401230213
Download: ML20086J131 (2)

Text

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

Subject:

Abnormal Occurrence The following' occurrence was reported to Mr. Wal t Baunack, A.E.C. Region 1 Regulatory Operations Of fice on December 16,1974 Written notification was made to Mr. James P. O'Reilly, Region 1 Regulatory Operations Office on December 16, 1974 In accordance with Section 6.7.2.A of the Technical Speci fications, Appendix A of DPR-56 for Unit 3 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing at an Abnormal Occurrence.

Reference:

License Number DPR-56 Technical Speci fication

Reference:

Table 4.2.B Report No.: 50-278-74-37 Report Date: December 26, 1974 Occurrence.Date: December. 16,'1974 Faci li ty: Peach Bottom Atomic- Power Sta tion R.D. //1, Del ta, -Pennsylvania 17314 Identi fication of Occurrer.ce: Failure of a torus high water level swi tch, LS-3-23-91A to ope ra te. This swi tch operates to _syway_p 11PCI suction from the con-densate storage tank to the suppression pool. 1 Im Conditions Prior to Occurrence: . Unit 3 at approximately 55% power.

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Description-of Occurrence: p -h . *- a- [ , During a routine instrument survei llance. test, LS-3-23-91 A -

       . failed to operate.

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                                                                                *   * 'e Mr. A. Giambusso Il U                                    I')

L December 26, 1974 Page 2 Designation of Apparent Cause of Occurrence: The switch assembly flapper arm was found to be slightly restricted by the swi tch case. Analysis of Occurrence: LS-3-23-91A and LS-3-23-910 operate independently to swap the HPCI suctior. from the condensate storage tank to the suppressior pool. LS-3-23-91B had just been tested and found to function properly. Because the failure of LS-3-23-91A to operate would not have interfered with the proper operation of the system, the safety implications are minimal. Corrective Action: Since a similar failure had occurred previously and a re-adjustment of the switch mechanism had been performed, it was decided this time to dismantle the float / shunt assembly. The shunt was found to have greater than an inch of excess vertical play. The amount of play was reducea to about one-sixteenth of an inch and the shunt moved higher on the float extension arm to allow adjustment of the switch assembly away f rom the base of the swi tch case. The switch was cycled a number of times using water to lif t the float, and then rechecked using the appropriate instrument surveillance test. Failure Data: A previous failure of this switch was reported as Abnonnal , Occurrence Number 50-278-74-25. Very truly yours, l'1 '] j. Yv , ll j M. J. Cooney Bu f Asst. Geni . Supt. Generation Division cc: ~ Mr. J. P. O'Reilly Di rector, Region i Uni ted States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406

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