ML19317F788
| ML19317F788 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/27/1975 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19317F789 | List: |
| References | |
| NUDOCS 8002210553 | |
| Download: ML19317F788 (1) | |
Text
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G:.]UB3 SACRAMENTO MUNICIPAL UTILITY DISTRICT C 1708 59th Street, Box 15830, Sacramento California 95813:(916)452 3211 March 11, 1975 7 hi
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Division of Reactor Licensing C
U.S. Nuclear Regulatory Commission C
4 Washington, D.C.
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Re: Operating License DPR-54 Docket No. 50-312 Abnormal Occurrence A0-50-312-75-3
Dear Sir:
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As defined by Proposed Amendment No. '30 to Technical Specificatio'ns for the Rancho Seco Nuclear Power Station, Section 6.9.1, and Regulatory Guide 1.16, Rev. 3, Section 2.b(1), we are reporting the following Abnormal Occurrence as A0-75-3.
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On February 12, 1975, during steady state ooeration at 9?T full nnuar the turbine-generator tripped when an overspeed trip relay falsely became de-energized. The reactor coolant pressure increased to 2355 psig tripping reactor protection high pressure channels A, B and C.
Reactor protection high pressure Channel D did not trip during the transient.
The pressure e
transmitter was checked with the original calibration data and the inforna,
tion revealed that the zero ref rence had drifted. This drift increased the pressure / response curve throughout the entire band resulting in an.
actual trip setpoint well above the specif.ied limit. The transmitter was removed from service and a unit of the same model was installed in its place. The new transmitter was calibrated and tested satisfactorily on February 12, 1975,the same day as the trip. The drifted pressure transmitter will be returned to the factory to determine the exact cause of. failure.
Since the remaining reactor protection high pressure channels have identical transmitter-units, a recalibration of the units to check the stability of the transmitter will be performed on each unit within sixty (60) days of
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this occurrence.
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The drifted unit was manufactured 'f:
Westinghouse Electric Corporation Veritrak Products Phoenix, Arizona 4
and is model number 59 PH 4443-7050.
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