ML20086D905
| ML20086D905 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 10/10/1973 |
| From: | Riley B VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20086D909 | List: |
| References | |
| AO-73-29, VYV-3051, NUDOCS 8312050649 | |
| Download: ML20086D905 (2) | |
Text
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U X 157 VEHNON, VERMONT oS354 October 10, 1973
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REFERENCE:
Operating License DPR-28 D
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'O Abnormal Occurrence No. A0-73-29 Gentlemen:
As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station. Section 6.7.3.1. we. are reporting the following At approximately 0900 on October 2, 1973, while performing a monthly functional test of the Reactor Protection System, a Drywell liigh Pressure switch (PSS-12A) failed to actuate at the required setpoint of <2 psig as specified in Table 3.1.1 of the Technical Specifications. The reactor was shutdown at the time of the incident.
Functionally, this switch operates in a one-out-of-two twice type logic and in a deenergized state actuates the Reactor Protection System. The three additional sensors monitoring drywell pressure were immediately tested and found to be actuating properly indicating that the system would have functioned if an actual high pressure existed in the drywell.
This switch was recet, functionally tested, and declared operable at 0930 on October 2, 1973.
The Plant Operations Review Committee (PORC), meeting to review the incident, concluded that this f ailure was an isolated instance of
" instrument drift" due to the fact that past surveillance testing relative to this parameter failed to indicate any previot.s discrepanci<:s.
8312050649 731010
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PDR ADOCK 05000271 S
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VERMONT V4KEE NUCLEAR POWER CORPORATION i
i Directorate of Licensing I
October 10, 1973
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Page 2 Since this sensor is tested on a monthly basis, no additional surveillance beyond that regularly scheduled was deemed necessary.
Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION O
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Bradford W. Riley Plant Superintendent WFC/kbd D
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