ML20086K592

AO 74-52:on 741115,setpoint Shift Found on RHR Loop Selection Jet Pump Riser Switches DPIS-2-2-129A & DPIS-2-2-129C.Caused by Setpoint Shift.Switch Actuating Arm Replaced,Switches Aligned,Rest & Checked

ML20086K592
Person / Time
Site:	Peach Bottom
Issue date:	11/25/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-74-52, NUDOCS 8401270330
Download: ML20086K592 (2)

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.9 PHILADELPHIA ELECTRIC COMPANY ,

2301 M ARKET STREET .,

PHILADELPHI A. PA.19101 ,

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November 25, 1974 Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, DC 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. Paul Nelson, A.E.C. Region i Regulatory Operations Office on November 16, 1974.

Written notification was made to Mr. James P. O'Reilly, Region i Regu-latory Operations Office on November 18, 1974. In accordance with Section 6 7 2.A of the Technical Specifications, Appendix A of DPR-44, t

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 Number 1 Technical Specification

Reference:

Table 3 2.8 Report No.: 50-277-74-52 Report Date: November 25, 1974 Occurrence Date: November 15, 1974

-Facility: Peach Bottom Atomic Power Station 1

R.D. 1, Delta, Pennsylvania 17314

_ Identification of' Occurrence:

Setpoint shift on RHR loop selection Jet Pump RiserAp switches dPIS-2-2-129A and dPIS-2-2-129C . >

Conditions Prior to Occurrence:

Unit 2 operating near. full power.

Description of Occurrence:

During routine instrument surveillance testing, dPIS-2-2-129A was found in the tripped condition and would not reset when equalized.

' By applying a 'dif ferential in the opposite direction, the switch was

. found to reset at -l.1 and to trip at -0 5 psid. dPIS-2-2-129C was found to trip at 0.25 psid. The Technical Specification limit is +0 5

<p51 5 psid 12073 8401270330741125 PDR ADOCK 05000277 S PDR

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J Page 2 Noseface 25, 1374' Desionation of Accarent Cause of Occurrence:

Setpoint shift partially attributable to component wear.

Analysis of Occurrence:

Even thcagh both switches in the 'A' logic for selection of the proper recirc loop for RHR (LPCI) injection were outside of the Technical Specification limits, dPIS-2-2-129C would still have correctly sensed the direction of dp and allowed f er the correct selection of a recirc loop for LPCI injection. Therefore, the safety implications of thi s setpoint shift are not significant.

Corrective Action:

dPIS-2-2-129-B and D were tested and found to be fully opera-tional. Preliminary investigation yielded two findings: 1, the set-point shift was aggravated by a factory adjustment which allowed the switch actuating arm to eperate on the knee of the actuation cam.

This made the setpoint adjustment very sensitive and the actuator travel very short; 2, the roller on the switch actuating arm was found to have worn slightly on the ' A' switch. The switch actuating arm was replaced, the switches aligned in accordance with an approved procedure, reset and checked for proper calibration per the applicable surveillance test.

Failure Data:

A previous setpoint shift on this device occurred on 12/12/73 and was reported as Abnormal Occurrence 50-277-73-16. A previous find-ing of improper f actory adjustment on this type of device was reported as Abnormal Occurrence 50-278-74-21.

Very truly yours,

, // l J.(do. oney g a t . .

<M.[s'tGeneral' Ap Superintendent Gencretion Division cc: Mr. J. P. O'Reilly Director, Region I United States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406 l

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