ML20086J520

AO 74-2:on 740729,refueling Floor Exhaust High Radiation Detector RIS-3-17-458D Found W/Trip Point in Excess of Tech Spec.Caused by Device Being Conservatively Set.Device Set to Trip at More Conservative Indicated Value

ML20086J520
Person / Time
Site:	Peach Bottom
Issue date:	08/08/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086J521	List: ML20086J520 ML20086J523
References
AO-74-2, NUDOCS 8401240052
Download: ML20086J520 (2)

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PHILADELPHIA ELECTRIC COMPANY g,. \,\ j

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.W August 8, 1974 Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Corgnission Directorate of Licensing Washington, DC 20545 50-278

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. R. A. Feil, A.E.C.

Region 1 Regulatory Operations Of fice on July 29, 1974. Written noti-fication was made to Mr. James P. O'Reilly, Region 1 Regulatory Opera-tions Of fice en, July 29, 1974. In accordance with Section 6.7.2.A of tha T.,-hnic.=1 % cificu<nne, n,n,n-,4ix A of DPD-56 f ar Vai t 3 Deee sottom atomic rcwer station, tne rollowing report is being submitted to the Directorate of Licensing as an Abnormal Occurrence. .

Reference:

License Number DPR-56 Technical Specification Table 3 2.D Report No.: 50-278-74-2 -

Report Date: August 8, 1974 Occurrence Date: July 29,1974 Facility: Peach Bottom Atomic Power Station -

R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

RIS-3-17-4580 refueling floor exhaust high radiation detector l was found to have a trip point in excess of the Technical Specification value during instrument calibration Conditions Prior to Occurrence:

Fuel loading of initial core in progress. h

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Description of Occurrence: \

R IS-3-17 i l SPD refueling floor exhau.st high radiatien monitor

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[ was ' found t o h we a t-io point of about 24 FP/P actual during instra-

[ ment calibration. Technical Specification required setpoint is 16 mR/HR.

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l Designation of Apparent Cause of Occurrence:

The device had been conservatively set to trip at 10 mR/HR indicated value. During the calibration of the device with an ex-ternal source, it was discovered that actual 16 mR/HR yicided an in-dicated value of 7 mR/HR. The device is a four-decade log device and this reading is within the instrument accuracy in percent of equivalent linear full scale. No problem exists with the instrumentation.

Analysis of Occurrence:

3 This device is one instrument in a.one-out-of-two-twice logic 1

which initiates a ventilation system isolation on refueling floor ex-haust high radiation. Since there is no irradiated fuel in Unit 3, there j is no situation which could create the initiating signal. There are

! no safety implications associated with this trip point deviation.

Corrective Action:

All four devices which monitor refueling floor exhaust high radiation were set to trip at a more conservative indicated value. This indicated value, when compared to the actual calibration trip value, is i significantly below the required actual 16 mR/HR in all cases.

Toilure Data:

This same problem occurred on a similar detector on Unit 2 and was reported as an Abnormal Occurrence on October 29, 1973 Very truly'yours,

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A. C6one'y Ass t Gen't Superintendent Generation Division 3 cc: . Mr. J. P. O'Reilly

' Director, Region i United States Atomic Energy Commission-631 Park Avenue King of Prussia, PA 19406 1

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