ML20086L518

AO 74-10:on 740316,setpoint Shifts Found on Switches PS-2-2-3-134C & 134D.Caused by Inability of Switch to Hold Precise Setpoints.Calibr Checked,Setpoint Reset & Checked in Accordance W/Surveillance Test

ML20086L518
Person / Time
Site:	Peach Bottom
Issue date:	03/21/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-74-10, NUDOCS 8402080288
Download: ML20086L518 (2)

Text

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March 21, 1974 ' -

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?(E Mr. A. Giambusso 50-277 Deputy Director of Reactor Projects United States Atomic Energy Coninission Directorate of Licensing Washington, D.C. 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. E. Brunner, A.E.C. Region I, Regulatory Operations Office on March 17, 1974 Written noti fication was made to Mr. James P. O'Reilly, Region I,

. Regulatory Operations Office on March 18, 1974. In accordance wi th Section 6.7.2.A of the Technical Specifications, Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-44, Amendment No. 1 Technical Specification Table 3.2.A Report No.: 50-277-74-10 Report Date: March 17, 1974 Occurrence Date: March 16, 1974 Faci li ty : Peach Bottom Atomic Power Station - Unit 2 R.D. #1, Del ta, Pennsylvania 17314

Identi fication of Occurrence: .

Setpoint shi f ts on PS-2-2-3-134C and PS-2-2-3-1340 which isolates the main steam lines if pressure drops below 850 psig when i

in the run mode.

l Conditions Prior to Occurrence:

l Plant stable at approximately 30% power. -

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8402000200 740321 PDR ADOCK 05000277 .

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p Hr. A. Giambusso 9 9 March 21, 1974 Page 2 Description of Occurrence:

During instrument surveillance testing, PS-2-2-3-134C and PS-2-2-3-134D tripped at approximately 841 psig and 847 psig, respectively, instead of 2 850 psig as specified in the Technical Speci fica ti ons.

Desionation of Apparent Cause of Occurrence:

I,nability of switch to hold precise setpoints.

Analysis of Occurrence: .

Setpoint shift of the subject switches would not have defeated the logic to produce the required actions. The operable switches in each channel would have caused trips at the proper setpoints. Setpoint shif ts were minor and have no safety implications.

Corrective Acticn:

The calibration was checked, setpoint reset and checked in accordance with the surveillance test. The remaining switches in this logic were checked and found to be within the Technical Specification limits. Investigation into the cause of long-term setpoint shift on this type of instrument is in progress.

Failure Data: ,

Two setpoint shi f ts outside the permissible range' have been previously reported on switches operating in the same pressure range in a different logic system.

Very truly yours, r i b ,/ <p(dc g M. . Cooney Ass}'tGen'tSuperintendent-

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Generation Division cc: J. P. O'Reilly-Director, Region I United States Atomic Energy Comnission 631 Park Avenue.

King of Prussia, PA 19406

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