ML20086J516

Telecopy AO 74-3:on 740820,setpoint of APRM Inoperable Trip Circuit Found Less Conservative than Allowed Tech Specs. Caused by Slight Setpoint Drift.Bistable Trip Device Recalibr

ML20086J516
Person / Time
Site:	Peach Bottom
Issue date:	08/21/1974
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086J513	List: ML20086J510 ML20086J516
References
AO-74-3, NUDOCS 8401240049
Download: ML20086J516 (2)

Text

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August 11, 1974

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A Mr. James P. O'ReillfEDTrector United Stat es Atomic Energy Cocsaission Directome of Regulatory Operations T 631 Par 6 '.v enue King of .ussia , Pettnsylvania 19406

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Subject:

Abnortaal Occurrence 24-Hour Notification -

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Confirming W. T. U11 rich's phone conversation with Mr. V. Baunack,

= 7~ ~A.E.degW1%gulatcdfUp~eranons MIice en August 21, 1974. ~@

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Reference:

License Number DPR-56 Technical Specification Table 3.1.1 Note 11 I

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50-278-74-3 I i Report No..

Report Date: August 21, 1974  !*

Occurrence Date: August 20, 1974 i Facility: Peach Botton Atomic Power Station %y*

f R. D. 1, Delta , Pennsylvanj2i 17314 I g Identification of Occurrence:

g Setpoint of APRM inop trip circuit less conservative than allowed by W the Technical Specifications. @-

aw-3i2E Conditions. Privr to Occurrence:

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The reactor was shutdown in a cold condition. A Jg=

Description of Occurrence: y During a surveillance tcat of the APRM systen the inoperative trip sigul from the LPRM count circuit was found to have it s setpoint out of the allowable tolerance on one APRM channel. The Technical Specification q requires that cach AFRM produce an inop trip when less than 14 cperable g LFRM inputs exist for that c hannel . The as found setpoint would have g allowed operation of APRM Channel B vith 12 operable LPRM inputs, g Designation of Apparent Cause of Occurrence: h g

Slight setpoint drif t of bistable trip device, er a

Analysis of Occurrence:

The APRM inop signal satisf actorily produced a scran and a rod withdrawal g block. The setpoint shif t was slight and of minical saf ety significance @

because no LFRM's in the APRM system were bypassed or otherwise inoperable. $

This trip is an electronic enforcement of an administrative limit that was g being complied with.

Corrective Action: $ --

The bistabic trip device was i::anediately recalibrated to produce an inop trip with less than 14 operable inputs. The survei lance test is being Y revised to change the LPRM dropout trip setpoint in the conservative direction. f =-

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8401240049 740830 c.g-PDR ADOCK 05000278 PDR  %

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Failuro Deto:

h previous foi en of this type cinco initial ibration.

Very truly yours, .

W. T. Ullrich, Superintendent Peach Bottom Atomic Power Station --

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