ML20086Q269

Ao:On 730911-12,setpoint Shift Found on Pressure Switches PS-2-5-120 & PS-2-2-3-550,respectively.Caused by Setpoint Set Too Close to Tech Spec Limit for Switch PS-2-5-120.Cause of Shift on PS-2-2-3-550 Unknown

ML20086Q269
Person / Time
Site:	Peach Bottom
Issue date:	09/19/1973
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8402270496
Download: ML20086Q269 (3)

Text

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• o o 50-277 PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET [$ )

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l] T [' Y 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 Occurrence

Dear Mr. Giambusso:

During the week of September 10, 1973. surveillance tests were performed on instrument systems required both for shutdown as well as power operating condi tions. Two setpoint shif ts in swi tch calibrations were noted and reported to Regulatory Operations. During the week, the reactor was in the shutdown condi tion and had not achieved ini tial cri ticall ty. .

The following items were reported to Mr. Tom Shedlowsky, A.E.C. Region 1, Regulatory Operations Office on September 12, 1973:

PS-2-5-l20 Setpoint Shif t 9/11/73 PS-2-2-3-550 Setpoint Shift 9/12/73 In accordance with Section 6.7.2.A of the Technical Specification

1. Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, these setpoint shif ts are being reported to the Directorate of Licensing as Ab-normal Occurrences.

PS-2-5-12C During routine instrument surveillance testing on 9/11/73, switch PS-2-5-12C was found to operate slightly beyond the Technical Specification limit of g 2 psig (Technical Specification Tables 3.1.1 and 3 2.A) . The "as found" setting was 2.02 psig. This switch supplies the High Drywell Pressure trip signa? to R.P.S. channel A-2 and to the P.C.I S.

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Investigation:

Investigation revealed.that the swi tch had originally been set so close to the Technical Speci fication limi t that it was possibic to remain wi thin the manufacturer's tolerance for this device and still exceed the limi t. The three other switches providing similar R.P.S. inputs were tested and found to be within the Technical Specification limits.

Corrective Acti on:

The acceptable setpoint ranges for these and other Technical Specification !imited iratruments are being re-evaluated to arrive at more viable setpoints where possible to allow a greater margin between the setpoint and the Technical Specifi-cation limits.

Safety Implications:

Since the requirement for primary containment integrity (Technical Specification. Limi ting Conditions for Operations -

3.7.A.2) does not exist at this time,. no safety hazard exists as a result of this failure. Addi ti ona l ' y, the operation of the companion switches would have correctly initiated action under high drywell pressure conditions.

PS-2-2-3-550 During routine instrument surveillance testing on 9/12/73, switch PS-2-2-3-550 was found to be out of calibration. This switch supplies the '

Reactor High Pressure trip signal to R.P.S. channel A-2. The "as found" setting was 1080 psig. The Technical Specification limi t is i 1070 psig (Technical Speci fication Table 3.1.1) .

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Inves ti ga tion:

Investigation of this setpoint shif t failed to disclose any specific reason for this shif t. The three other switches providing similcr R.P.S. inputs were tested and found to be wi thin the Technical Specification limi ts.

Corrective Action:

The acceptable setpoint ranges for these and other Technical Specification limited instruments are being re-evaluated to arrive at more viable setpoints where possible to allow a greater margin between the setpoint and the Technical Specifi-

cation >1imi t.

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• i Safety Imolications:

The shif t in setpoint of this switch presents no safety hazard since these R.P.S. inputs are not required when the reactor is suberitical and the reactor water temperature '

is less than 212 F (Technical Specification Tabic 3.1.1, note 7). These conditions exist at the present time.

Additionally. the operation of the companion switches would have correctly initiated action under reactor vessel high pressure condi tions.

1 Very truly yours.

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M. _. Cooney i Ass' t. General Superintendent Generation Division MJC:1pm j cc.: Mr. J. P. O 'Rei l ly 4

Director. Region 1 f

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