ML19345G172
| ML19345G172 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 01/28/1974 |
| From: | Hartley F CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| AO-74-02, AO-74-2, CYH-2580, NUDOCS 8103100175 | |
| Download: ML19345G172 (1) | |
Text
'Qf,g I5 OI' CONNECTICUT YANKEE ATOhkiC POWER COMPANY CL-HADDAM NECK PLANT RR 21. BOX 127E. EAST HAMPTON, CONN. 06424 January 28, 1974 CYH-2580
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'p'Ai(/[NixqU Mr. A. Giambusso Deputy Director for Reactor Projects 50-213
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Directorate of Licensing United States Atomic Energy Commission y g,i_[
Office of Regulation H
Washington, D. C. 20545
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Dear Mr. Giambusso,
As defined by Technical Specifications for Connecticut Yankei-Atomic Power Station Section 5.3, the following information involving the malfunction of two main steam line excessive flow differential pressure transmitters is reported as Abnormal Occur,ence 74-2.
At 0612 on 1/18/74, a data logger alarm message was received indicating a main steam line high steam flow condition in the #2 steam line. Two minutes later a similar high steam flow condition was annunciated for the #1 steam line. The coincidence of two high steam flow signals satisfied the tripping logic and a reactor / turbine trip occurred from full power (s 600 MWe).
Subsequent investigation revealed frozen instrument sensing lines leading to the differential pressure transmitters for the #1 and #2 main steam line excessive flow instruments. The instrument sensing lines were thawed and the instrumentation returned to normal.
The instruments in question are housed in an enclosure attached I
to the outside of the reactor containment.
Sub-zero temperatures and l
strong winds created the freezing environment. Additionally two unit heaters in the affected area were not operating.
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The two unit heaters were repaired and returned to service. Two additional electrically operated, thermostatically controlled heaters were placed in the affected enclosure for backup freeze protection.
l Several openings to the outside environment are in the process of being sealed.
With the installation of backup electrical heaters and sealing the several openings, it is not expected that this situation will reoccur, yN 4
i gg' Very truly yours, fe kh@&
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. W. Hartley
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cc: Mr. James P. O'Reilly, pd/d$/K DR0