ML20086J108

AO 74-40:on 741224,setpoint Shift Found on RHR Loop Selection Jet Pump Riser Switches DPIS-3-2-129B, DPIS-3-2-129D & DPIS-3-2-129A.Caused by Constant Cyclic Action & Low Differential Pressure Range

ML20086J108
Person / Time
Site:	Peach Bottom
Issue date:	01/03/1975
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A Office of Nuclear Reactor Regulation
References
AO-74-40, NUDOCS 8401230181
Download: ML20086J108 (2)

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- PHILADELPHIA ELECTRIC COMPANY l.JJ 2301 MARKET STREET . ;;

PHILADELPHIA. PA.19101 , 'l JI Q%3s g'jt " 7

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, --f taisi o414ooo ..,g,-ji 3 , ff January 3, 1975 -

s tir. A. Giambusse ~:" '.

- Deputy Director of Reactor Projects , .

United States Atomic Energy Commission Di rectora te of L'icensing Washi ng ton, D.C. 20545

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Subject:

Abriormal O currence The following occurrence was reported to Mr. Wal t Baunack, A.E.C. Region _1, Regulatory Operations Office on December 24, 1974.

Written notification was made to Mr. James P. O'Reilly, Region 1 Regulatory Operations Office on December 24, 1974. In accordance with Section 6.7 2.A of the Technical Specifications, Appendix A of DPR-56 for Uni t 3 Peach Bottom Atomic Pownr Station, the folinwing report is being submj tted to the Directorate of Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-56 Technical Specification

Reference:

3 2.B Report No.: 50-278-74-40 Report Date: January 3,1975

_ Occurrence Date: December 24, 1974 Faci li ty r Peach Bottom Atomic Power Station

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

Setpoint shif t on RHR loop selection jet pump riser 4P

} swi tches, dPIS-3-2-1299, dPIS-3-2-1290, and dPIS-3-2-129A.

Condi tions Prior to Occurrence:

u Unit 3 oparating at 72% power.

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_De'scription of Occurrence:

x During routine instrument surveillance. testing, dPIS-3-2-1298

+ was found in the tripped condition and would not reset. dPIS-3-2-129D

>..was found to trip at 0.45 psid. The technical specification limit is  !

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8401230161 ppR ADOCK 05000278 750103

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PDR pg

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Hr. A. Giambusso January 3, 1974 Page 2 ,

0. 5 < p < 1. 5. As part of the corrective action, .the remaining two switches were then tested with the following results: dPIS-3-2-129A was found to trip at 0.48 psid. The "C" switch was within the technical speci fication limi ts.

Designation of Apparent Cause of Occurrence:

These switches are subject to a constant cyclic action due to the normal pressure di fferences between the . jet pump loops. This action plus the low di fferential pressure range that these swi tches most respond to make them prone to setpoint drif t, the. apparent cause of this occurrence.

Analysis of Occurrence:

The jet pump riser t.P is used in the LPCI loop selection in a one out of two twice logic. With the conservative assumption that the "B" swi tch would not have reset under reverse d/p condi tions, the other switches still would have provided the correct LPCI loop selec-tion logic inputs, since they were proven to be functional, and they were only slightly outside the technical spect fication limits. .There-fore, the safety implications of this occurreace are considered to be mi nima l .

Cortecti ve Action:

dPIS-3-2-129B and D were immediately calibrated and checked for proper operation per tbc applicabic surveillance test. The.re-maining two switches were then tested at which time the "A" swi tch was found to be slightly outside the technical specification limits, as described above. The "C" swi tch was satis factory. The "A" swi tch was then calibrated and checked-for proper operation in accordance with the applicable surveillance test.

Failure Data:

Previous failures of this type have been reported in abnormal occurrences 50-277-73-16, 50-278-74-21, and 50-277-74-52.

Very truly yours,'

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M.

Ass,J. Cooney

t. Gen 1. Supt.

Generation Division

- cc: Mr. James P. O'Reilly . '

Di rector, Region 1 United States Ato:nic Energy Commission i 631' Park Avenue *

,. . King - of Prussia, PA 19406 n

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