ML19291B529

Abnormal Occurrence 50-289/75-15:on 750605,pressure Transmitter Trip Setpoint of Reactor Protection Sys Channel B Tested Out of Calibr.Caused by Trip Setpoint Calibr Drift

ML19291B529
Person / Time
Site:	Three Mile Island
Issue date:	06/13/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
Shared Package
ML19291B530	List: ML19291B529 ML19291B532
References
GQL-1153, NUDOCS 7911080560
Download: ML19291B529 (4)

Text

NRC 6 - sTRIBUTION FOR PART 50 DOCKr a1ATERIAL ,

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CONTROL NO: 00/2-w FILE: INCIDE!.T REPORT FILI FROM: M*tr Potitan Edison CompanDATE OF DOC DATE REC'O LTR TWX RPT OTHER Reading, Pa R C Arnold 6-13-75 6-19-75 XXX ORIG CC OTHER SENT AEC POR XX TO:

DI, one signed SENT LOCAL PDR XX CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:

XXXXXXXXX 1 50-289 DESCRIPTION: ENCLOSURES:

Ltr reporting abnormal occurennce #75-15 on 6-5-75. . . . concern ing our of limits -

setting for the reactor co&lant pressure p** A 7

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Dear Sir:

Docket No. 50-289 Operating License No. DPR-50 In accordance with the Technical Specifications of our Three Mile Island Nuclear Station Unit 1 (TMI-1) , we are reporting the following abnormal occurrence. ,,%

'- s (1) Report Number: A0 50-289/75-15 p,y\ gz,g, v c:: 2

...s (2a) Report Date: June 13, 1975 7 "";

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• 0' (2b) Occurrence Date: June 5, 1975 --l- k k. -. _' _. i-d

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(3) Three Mile Island Nuclear S tation Unit 1 u s r d'

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(4) Identification of Occurrence:

Title:

Out of Limit Setting for the Reactor Coolant Pressure Trip Setpoint.

Type: An abnormal occurrence as defined by the Technical Specifications, paragraph 1.8a, in that the out of limit setting for the reactor coolant system (RCS) was less conservative then the limiting settings established in the Technical Specifications.

(5) Conditions Prior to Occurrence:

The reactor was in a cold shutdown condition with major plant parameters as follows:

Power: Core: 0%

Elec.: 0 MWe 1583 175 6812

RC Flow: 0 lbs/hr.

RC Press: 0 psig RC Temp: 122 F PRZR Level: 270 in.

PRZR Temp. : 122 F (6) Description of Occurrence:

On June 5,1975, pressure transmitter calibration and corresponding pressure trip setpoints were being checked in accordance with Refueling Interval Surveillance Procedure 1302-5.2 & 5.3, "High and Low RC Pressure Channels ." Reactor Protection System Channel B was bypassed and the associated pressure transmitter was checked by applying measured test pressures. This check revealed that the pressure transmitter was out of calibration, resulting in a high pressure bistable trip setpoint that was less conservative than allowed by the Technical Specifications. The transmitter was immediately recalibrated and Reactor Protection System Channel B was returned to service.

Each of the remaining pressure transmitters was checked in sequence by insuring all channels were in service and then bypassing the applicable Reactor Protection System channel, applying test pressures , checking transmitter calibration and pressure trip setpoints, and returning the channel to service before proceeding to the next channel. All high and low pressure trip setpoints for these channels were found to be within Technical Specifications limits.

Die "as-found" setpoint (before transmitter recalibration) and the required setpoint for the channel out of specification was as follows:

Table 2.3-1 Applicable Measured High Pressure Channel Trip Setpoint Trip Point B 2355 2377 (7) Designation of Apparent Cause of Occurrence:

The apparent cause of the occurrence was the component in that the out-of-specification trip setpoint was due to minor calibration drif t in the Reactor Coolant System pressure transmitter. The transmitter was last calibrated less than seven months ago (November 22,1974) , less than the refueling-interval period required by the Technical Specifications.

Procedural modifications noted in the long-term corrective actions of our Abnormal Occurrence Report 74-24 (dated December 2,1974) have been made.

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(8) Analysis of Occurrence:

It has been determined that the out-of-limit setpoint did not constitute a threat to the health and safety of the public for the following reasons:

a. The setpoints for the other 3 RPS channels were within limits, and these channels would have performed their protective function within Technical Specification limits had an overpressure condition occured.

b. The trip setpoint setting for the channel out-of-specification was more conservative than that used in Chapter 14 of the TMI-l Final Safety Analysis Report.

(9) Corrective Action:

Short term corrective action was taken as described above to recalibrate and retest the out of specification transmitter and to return the affected Reactor Protection System channel to service.

Long term corrective action wil] be taken to submit a Technical Specification change request to permit a 30 psig transmitter calibration drif t (which is within the limits established by the safety analysis) as noted in our Abnormal Occurrence Report 74-24 dated December 2,1974.

The Plant Operations Review Committee and S tation Superintendent reviewed and approved the above actions.

(10) Failure Data:

a. Previous Failures: See Abnormal Occurrence Report 50-289/74-24.

b. Equipment Identification Westinghouse Electric Corporation Reactor Coolant System Narrow Range Pressure Transmitter Model 59 PH Sincerely, f

R. C . rnold Vice President RCA: RS B : tas File: 20.1.1 / 7.7.3.5.1 cc: Office of Inspection and Enforcement Region I 1583 177