ML20086K475

AO 75-9:on 750125,setpoint of APRM C Inoperable Trip Circuit Found Less Conservative than Allowed by Tech Specs. Caused by Accidential Gain Change to Circuit.Trip Unit Recalibr

ML20086K475
Person / Time
Site:	Peach Bottom
Issue date:	02/04/1975
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A Office of Nuclear Reactor Regulation
Shared Package
ML20086K477	List: ML20086K475 ML20086K487
References
AO-75-9, NUDOCS 8401270135
Download: ML20086K475 (2)

Text

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O O s PHILADELPHI A ELECTRIC COMPANY , '.

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2301 MARKET STREET IEO S $U/,5 '

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February 4, 1975 >

Mr. A. Giambusso Director, Division of Reactor Licensing Office of Nuclear Reactor Regulations United States Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Giambusso:

Sub' ject: Abnormal Occurrence The following occurrence was reported to Mr. Robert Carlson, N.R.C. Region 1 Of fice of Inspection and Enf orcement on January 25, 1975 Written notification was made to Mr. James P. O'Reilly, Region 1 Of fice of Inspection and Enforcement on January 25, 1975 In accordance with Section 6.7 2.A of the Technical Specifications, Appendix A of DPR h4 for Unit 2 Peach Bottom Atomic Power Station, the followina report is being submitted to the Director of Reactor Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-44 Technical Specification

Reference:

Table 3.1.1 Note 11 Report No.: 50-277-75-9 Report Date: February 4,1975 Occurrence Date: January 25, 1975 Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

Setpoint of APRM "C" inop trip circuit less conservative than allowed by the Technical Specifications.

Conditions Prior to Occurrence:

Unit 2 at 65% power.

Description of Occurrence:

During a routine surveillance test of the APRM system, the inop trip setpoint in the LPRM count circuit s:as found out of the allowable tolerance on one APRM channel.

8401270135 750204 PDR ADOCK 05000277 S PDR

v v-Mr. A. Giambusso n U Page 2 February 4, 1975

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Designation of Apparent Cause of Occurrence:

Apparent accidental gain change to this circuit during APRM gain correction for startup.

Arialysis of Occurrence:

The APRM inop signal satisfactorily produced a scram and a rod withdrawal block. The setpoint error is of minimal safety sign.if-icance because only one LPRM in this APRM channel was bypassed or in-operable at the time. This trip is an electronic enforcement of an administrative limit that was being complied with.

Corrective Action:

The bistable trip device was checkad to ensure that the only problem was the accidental setpoint change. The trip. unit was then recalibr ated to be more conservative than the Technical Specification limit. This was checked in accordance with the applicable surveillance test and the APRM was returned to service.

Failure Data:

Previous APRM inop setpoint shift reported as 50-278-74-3 Very truly yours, M. J. Cooney Ass't Gen' t Superintendent Generation Division cc: Mr. J. P. O'Reilly, Director Office of Inspection and Enforcement Region 1 United States Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406