ML20086K479

AO 74-34:on 740627,rod Block Setpoint of Two APRMs Exceeded Tech Spec Limit.Caused by Instrument Channel Drift. Setpoints Recalibr within Tech Spec Limits

ML20086K479
Person / Time
Site:	Peach Bottom
Issue date:	07/07/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-74-34, NUDOCS 8401270136
Download: ML20086K479 (2)

Text

. - - _ _ . . - - . .

O O ,

PHILADELPHIA ELECTRIC COMPANY ri

,p- ;: 0 ^ , N, 2301 MARKET STREET / ,

PHILADELPHIA. PA.19101 f b fit LI hW ) 9%I

e. 121518414ooo Q Cs JULU197.b.

a* ' ; c '.nt f &)

v

C hY. + w[, ; :,' /

July 7,1974 Q,%.  !.J)y -,,,,f )

Mr. A. Giambusso '

Deputy Director of Reactor Projects United States Atomic Energy Commiss ~1 Directorate of Licensing Washington, DC 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. Tom Shedlowsky, ,

A.E.C. Region 1 Regulatory Operations Office on June 28, 1974. Written notification was made to Mr. James P. O'Reilly, Region I Regulatory Operations Office on June 28, 1974. In accordance with Section 6 7 2.A o.~ ti e Teclin i o. i Aner.i f ic a r i nns , u,nna nce i v a ne sweuq*e em: 2 Pc _.-h 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 3 2.C Report No.: 50-277-74-34 F eport Date: July 7, 1974 Occurrence Date: June 27, 1974 Facility: Peach Bottom Atomic Power Station .

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

Rod block setpoint of two average power range monitors exceeded technical specification limiting setting by less than 0.4%.

Conditions Prior to Occurrence: <

The reactor was at 97% power.

Description of Occurrence:

During a routine functional and calibration surveillance test of the JPRM system, two channels were found to hwe their rod block tri .

setpoints in excess of the technical specification upper limit '

r

' ,l O' '

() ' ' (,)

8401270136 740707 PDR ADOCK 05000277 S PDR (A/'v [ ~,

' lf )

j

~O(JrY SERr REGION.

Mr. A. Giambusso (

July 7, 1974 Page 2 Channel A exceeded the limit by 0.4%' power and Channel D exceeded the limit by 0.2% power.

Designation of Apparent Cause of Occurrence:

1 A review of the previous wcek's APRM surveillance tests in-dicated that the trip setpoints were left in the conservative direction by less than 1.0% power. The setpoint failure is, therefore, attributed to slight instrument channel drift.

Analysis of Occurrence:

Due to the minimum 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 channels can initiate a rod block), this occurrence has minimal safety significance. a Corrective Action

~

The rod block setpoints of the two out of specification fi 4

channels were immediately recalibrated to within the technical speci-fication limits. The scram and rod block setpoints of all six APRM -

J channels were innediately checked and found to be satisfactory. The calibration procedure has been changed to provide a 1% conservative -

setpoint to prevent recurrence. These setpoints have been applied to ,{

each channel. --

l Failure Data:. j i

L No previous failures of this type.

]

, Very truly yours, i

I }' s[Lbl.lL M.f.Cooney

, Ass t Gen'1 Sup,erintendent t l

Generation Division l

. cc: Mr. J. P. O'Reilly ,

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

. fn

, l

! lI b

r s I-

_ _ - . _ _ _ _ _ _ . _ . _ _ . _ . _ . _ _