ML20086Q218

Aos:On 730904,06-08,setpoint Shift Found on Pressure Switch PS-2-14-44A & Intermediate Range Monitor Channel C & Functional Failure Found on Differential Pressure Switch DPIS-2-119A & Level Switch LB-2-3-231D

ML20086Q218
Person / Time
Site:	Peach Bottom
Issue date:	09/14/1973
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8402270477
Download: ML20086Q218 (4)

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'Ei PHILADELPHIA ELECTRIC COMPANY l

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, i- September 14, 1973 Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, D. C. 20545

Reference:

Peach Bottom Atomic Power Station - Unit #2 Facility Operating License DPR-44 Docket No. 50-277

Subject:

Abnormal Occurrances

Dear Mr. Giambusso:

During the week of September 3, 1973, surveillance tests were performed on instrument systems required for both the shutdown as well es power operating condition. Certain set point deviation and switch deficiencies were noted snd reported to Regulatory Operations, at the present time the reactor is in the shutdown condition -- having just received the initial fuel load. The reactor has not yet been brought to the critical condition, therefore, safety problems associated with heat removal and -

radiation do not exist. y The following items were reported to Mr. T. Shediowsky, AEC Region 1 Regulatory Operations Office on .the dates indicated: .

PB-2-14-44A Setpoint Shift 9/5/73 dPIS-2-2-119A Functional Failure 9/7/73 l(Isf IRM Chan C Setpoint Shift 9/7/73 3h) LB-2-3-231 D Functional Failure 9/9/73

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, In accordance with Section 6 7.2.A of the Technical Specification

(,[ Appendix A of DPR-44 for Unit #2 Peach Bottom Atomic Power Station, these fail-T, ures are being reported to the Directorate of Licensing as Abnormal Occurrances, ys-

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_ . . . _ _ _ _ . - ~ _ __ E=d n G O V PS-2-14-44A 9/4/73 During routine instrument surveillance testing on 9/4/73, pressure switch PS-2-14-44A was found to be out of calibration. The acceptable range for this switch is 185 + 5 psig. The "as found" setpoint was 191.7 psig, which is less than 2 PSI out of limit. This switch is used in the Automatic Depressuri-zation System logic to provide the " Core Spray Pump Running" interlock permissive (at 185 + 5 psig, Tech. Spec. Table 3 2.8) .

The switch was recalibrated, retested according to the same instrument surveillance procedure ST 2.1.04A, and found to be within acceptable limits.

Inve st i gati on Investigation of this setpoint shif t f ailed to disclose any specific reason for this shif t.

The remainder of the switches used in this same type of application were checked and found to be satisfactory. This consists of four en the Core Spray System and eight on the Residual Heat Removal System.

Corrective Action No further corrective action was deemed necessary.

Safety Implicatiens The f ailure of this switch presents no safety hazard to the plant under the present conditions in that the reactor contains no irradiated fuel and has no decay heat. Additionally, the Technical Specifications indicate (Section 3.5.E.1) that the Automatic Depressuri zation System of which this switch is a part is not needed to be operable if there is no irradiated fuel in the reactor or the reactor pressure is less than 105 psig. The plant presently meets both of these conditions. -

2 dPIS-2-2-119A 9/6/73 During routine instrument surveillance te' sting on 9/6/73, differential pressure switch dPIS-2-2-Il9A was found to be inoperative. This switch is used in the main steam line leak detection circuit to provide the main steam line High Flow signa! to the Primary Containment Isolation System Logic to initiate Main Steam Line Isolation Valve Closure.

Investigation It was found that the switch could be actuated at the setpoint by tapping the case. Internal inspection revealed that the linkage was binding slightly at the first pivot point. Straightening of the hold down plate at the pivot allowed the linkage to then operate freely.

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N e 4 O.e O 3- l The calibration was rechecked and the instrument returned to service.

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Corrective Action The remaining switches of this type are being investigated for binding and for proper se'tpoint to preclude repetition of this type failure.

Safety Implications Since the requirement for primary containment integrity (Tech.

Spec., Limiting Conditions for Operation, 3 7.A.2) does not exist at this time, no safety hazard exists because of this failure.

IRM Channel C 9/7/73 During routine neutron monitoring system surveillance testing on 9/7/73, both the HI and the HI-HI setpoints on IRM Channel C were found- to be out of calibration. The acceptable setpoints are as follows:

a. HI, which provides a rod block, ~

108 indicated on scale (Tech.

Spec. Table 3 8.0)

b. HI-HI, which provides a scram input, - 120/125 of full scale (Tech. Spec. Tabic 3.1.1)

The "as found" setpoints were:

a. HI trip at 109

b. 'HI-HI trip at 120 5 The Dual Trip Unit was recalibrated, and re-tested using the same surveillance test ST 3 2.1, found to be within acceptable limits, and returned to service. ,

e Investigation ~"

The setpoint drif t was found to be wholly within the G. E. Qual Trip Unit which has exhibited drif ting in the past. The observed drift has been in the range of less than 1% per month. No component f ailures were evident.

Corrective Action Since there is no requirement to have these setpoints this close to the upper limit, the ' Instrument Group was directed to reset the trip points to 116% for the HI-HI trip (Scram) and 104% for a HI trip (Rod Block) . This permits a greater drift in the trip unit before a setpoint limit is reached.

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i Safety Implications The Plant Operations Review Committee agreed that this minor drif t in setpoint did not have any safety effect in that with the non-coincident i scram circuits presently installed, the required scram would have occurred on the other channels which were correctly calibrated.

LB-2-3-231D 9/8/73

' During routine instrument surveillance testing on 9/8/73, level switch LB-2-3-2310 was found to be inoperative. This switch is one of four which pro-vide scram inputs on Scram Discharge Volume High Level.

4 Investigation Internal investigation showed that the switch mechanism was binding slightly. Readjustment of the float mechanism succeeded in freeing the switch movement. The trip calibration was then checked using the " calibration check" surveillance procedure ST 2.4.110, and the instrument returned to service.

Corrective Action -

j The other three level switches which provide the same reactor pro-

tection system input (scram) were checked for binding and for proper

setpoint and found to be free and acceptable.

! Safety Implications

, According to the Technical Specifications, note 7 to Table 3.1.1, the Scram Discharge Volune High Level switches are one of the four-scram functions required to be operable when the reactor is subcritical and the reactor water temperature is less than 2120F. The other oper- ,

able switches in the scram circuit would have properly-caused a reactor

scram should discharge volume high level have occured.  ?

4 l Very truly yours,. ,,

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.'h' . Coo mG(ney /

Ass't General Superintendent j G4neration Division 4

i cc: J. P. O'Reilly Director, Region 1 l

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