ML20086Q286

Ao:On 730824,reactor Level Switch LIS-2-2-1-101B Found to Have Setpoint of -15 Inches Reactor Level.Caused by Switch Sensitivity to Calibr Adjustments.Switch Recalibr,Checked & Returned to Svc

ML20086Q286
Person / Time
Site:	Peach Bottom
Issue date:	08/31/1973
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8402270501
Download: ML20086Q286 (2)

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August 31, 1971 j

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NL._ W 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 performance of a surveillance test on 8/24/73, a reactor level indicating switch (LIS-2-2-3-1010) was found to have a setpoint of approximately -15" reactor level . The required setpoint for thi s switch is 1.2 to 0" reactor level . This event was reported to Mr. B. Davis, A.E.C. Region i Regulatory Operations Office on 8/25/73 In accordance with Section 6.7 2.A of the Technical Spect-fication Appendix A of DPR-44 for , Unit #2 Peach Bottom Atomic Power Station, this failure is being reported to the Directorate of Licensing as an Abnormal Occurrence.

. The instrument utilizes two switches for protective actions, which are identified as switch #1 and #3 The acceptable range for switch #1 is 62.5" to 63 3" H 2O (corresponds to 1.2 to 0 inches reactor level). The "as found" setpoint for switch #1 cas approximately 74" H2 O (corresponds to -15 inches reactor level). Switch #1 is used in the reactor protection system to provide the reactor low level (?_0 inches reactor level, Tech. Spec. table 31.1) scram input signal to RPS channel B-1.

The acceptable range for switch #3 is 31.5" to 32 3" H 2O (correspands to 45 to 43.8 inches reactor level). The "as found" setpoint for switch #3 was approximately 37" H 2O (corresponds to 37.2 ,

inches recctor level). Switch #3 provides the high reactor water I level trip signal to the HPCI and (145 inches reactor level; l Spec. Tabic 3 2.B) reactor feed pump turbines. Tech.

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B402270501 730831 PDR ADOCK 05000277 COT'T hECTONM b S PDR

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r . o Psga 2 gust 31, 1973 After the switch was retested according to the same instrument surveillance procedure ST 2.4.100, It was found to be within acceptable limits.

INVESTIGATIO!!

The instrument is a model 288A Barton Ap switch, which it very sensitive to calibration adjustments.

There are four instruments of this type and model which have been tested. The "D" instrument was tested and found acceptable. The "A" and "C" instruments were found to have their #3 switch out of calibration. .

The #3 switch on the "A" instrument was in the unsafe direction as defined by the Technical Specifications as greater than +45 inches reactor level ("as found" setpoint was approximately

+S7 inches reactor level). The failure on the #3 switch on the "C" instrument was in the safe direction, less than +45 inches reactor Icvel ("as found" setpoint was approximately +43 inches reactor Icvel).

CORRECTIVE ACTI0ft:

Each of the switches has been recalibrated, checked by the appropriate instrument surveillance test, and returned to service.

Further, tnese instruments will be calibration checked by the same instrument surveillance test once per week until the reliability of the instrument is determined. The manufacturer has been contacted and will be consulted throughout the investigation.

SAFETY IMPLICATIONS:

At the present time, witrh only new fuel within the reactor '

vessel there are no safety implications associated with the setpoint drif t of these switches. Additionally, the Technical Specifications-permit these switches to be inoperable with the reactor sub-critical ..

0 and the reactor water temperature below 212 F, which is the present '

condition of the reactor. The surveillance testing was performed on a routine basis in anticipation of future start-up operations in the plant.

l Very truly yours, jL-f% L '

M. . Cooney A t. Gent. Supt.

Generation Division i

HJC:1pm cc: J. P. O'Reilly, Directorate of Regulatory Operations, Region I

.