ML20086J270

AO 74-18:on 741024,rod Block Setpoint of Average Power Range Monitor Channel D Less Conservative than Allowed by Tech Specs.Caused by Setpoint Drift.Rod Block Setpoint Recalibr

ML20086J270
Person / Time
Site:	Peach Bottom
Issue date:	11/04/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-74-18, NUDOCS 8401230542
Download: ML20086J270 (2)

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November 4, 1974

. J["vfg e D- ,'*w] 9 Mr. A. Giambasso Deputy Director of Reactor Projects United States Atomic Energy' Commission Directorate of Licensing Washington, DC 20545

Dear Mr,

Giambus,30-

Subject:

Abnorggi Occurrence he following % $rrence was reported to Mr. Valt Baunack, A.E.C. Regico 1 RegulatNy Operations Of fice on October 29, 1974.

Written notification was made to Mr. James P. O'Reilly, Region I s.

Regulatory Operations Office on October 25, 1974. In accordance with Section 6.7.2.A of the Technical Specifications, Appendix A of DPR-56 _

for Unit 3 Peach'PIdttem Atomic Power Station, the following report is being submittad to the Directorate of Licensing as an Abnormal Occurrence.

Reference:

License Namber DPR-56 .

Technical Specification Reference Table 3 2.C Report No.: 50-278-74-18 Report Datee November 4, 1974

• Occurrcnce Date: October 24, 1974 Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

Rod block setpoint of the APRM channel'"D" less conservative 5

'than allowed by the Technical Specificatiens.

Cond tions Prior to Occurrence: "# '

The reactor was at 48/3 pcwcr.

Description of Occur _ren_ce: -

, During a reutine functional and calibration surveillance test of the APRM system, channel 0 was found to have i ts rod block trip set ,~

point less conservative than the Technical Specification upper limit of -

(66W+42) 2.63. The lirait was exceeded by 0 94 power.

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Mr. A. Giambusso U l November 47 1974 Page 2 i Designation of Apparent Cause of Occurrence:

The failure is attributed to setpoint drift.

Analysis of Occurrence:

Due to the slight deviation from the Technical Specification limit and the redundancy of the APRM system in its ability to initiate a rod withdrawal block (any one of the six APRM channels can initiate a rod block), this occurrence has minimal safety significance.

Corrective Action:

The rod block setpoint was immediately recalibrated to within the Technical Specification limits. Investigation of_the flow biased trip unit yicided no clues to the setpoint drift. The scram and rod block setpoints of all six APRM channels were checked and found to be satisfactory.

Failure Data:

One other f ailure of this type was reported as 50-277-74-34.

Very truly yours, Vl .f 3 u.a f M. J. Coon ey Ass't Gen'1 Superintendent Generation Division cc: Mr. James P. O'Reilly United States Atomic Energy Commission Directorate of Regu;atory Operations 631 Park Avenue King of Prussia, PA 19406 I