ML19343C288
| ML19343C288 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 01/23/1976 |
| From: | Graves R CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| CYH-3160, RO-76-1-P, NUDOCS 8103050136 | |
| Download: ML19343C288 (1) | |
Text
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..o CONNECTICUT YANKEE ATOMIC POWER COMPANY
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HADDAM NECK PLANT RR ;* 1. BOX 127E. EAST H AMPTON. CONN. 06424 tb January 23, 1976 o
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50 - Rl3 U. S. Nuclear Regulatory Commission Directorate of Regulatory Operations Region I 631 Park Avenue King of Prussia, Penns';ivania 19406 Attention: Mr. James P. O'Reilly, x
Director sQ
Dear Mr. O'Reilly:
In accordance with the reporting requirements of Connecticut Yankee Technical Specifications, Section 6.9.2.a, the following preliminary report (76-1/P) concerning the malfunction of two main steam excess flow differential pressure transmitters is hereby submitted.
During severe sub-ze:ro weather conditions, sensing lines to two high steam flow differential pressure transmitters froze.
The coincidence of the two high steam flow signals satisfied the tripping logic and a reactor /
turbine trip occurred from full power (s 593 i?.!a).
The instrument sensing lines were thawed and the instrumentation returned _a normal.
The-instruments in question are housed in an enclosure attached to the outside of the Reactor Containment. Sub-zero temperatures and strong winds coupled with some openings inadvertently left in the wall as a result of a recent (high energy pipe break) modification to the enclosure overcame the enclosure heating system and caused local free:ing of the sensing lines.
The enclosure building openings were plugged and additional freeze pro-tection was applied to the sensing lines.
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g p--q% i Very truly yours,
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Richard H. Graves, Ic7 f s ,ga,; 7 4l}/
Plant Superintendent
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