ML17252A896

Letter Regarding a Change in Analysis of the Causative Factors Relating to an Occurrence Detailed in a May 25, 1973 Letter - Indian Point Unit 2

ML17252A896
Person / Time
Site:	Indian Point
Issue date:	07/23/1973
From:	Caldwell W Consolidated Edison Co of New York
To:	O'Leary J US Atomic Energy Commission (AEC)
References
Download: ML17252A896 (2)

Text

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William E. Caldwell.A.

';..-;~.-* L~/ Vice President W 50-247 Consolidated Edison Company of New York, Inc.

~OM~-~~~~.*4 Irving Place. New York.NY 10003

," *, lephone (212) 460-5181

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\ July 23t 1973 Re: Indian Point Unit No. 2 Facility Operating License DPR-26 Mr. John F. O'Leary, Director Directorate of Licensing

u. s. Atomic Energy Commission*

Washington, D.C. 20545

Dear Mr. O'Leary:

1 ~

By letter dated May 25, 1973, you were informed of Abnorrn'i:tf' Occurrerite No. 3-2-5, and of the action Consolidated Edison intended to take to prevent its repeti t'ion. This letter is to advise you of a change* in our analysis of the causative factors relating to the occurrence, and to apprise you of our current plans with regard to remedial measures.

In my previous letter, an apparent design deficiency with respect to the suction valve for the refrigerant dryer com-pressor was identified as the principal cause of the occur-rence, viz, it appeared that placing the valve in the full-open, or back-seated, position caused isolation of a pres-sure sensor and this, in turn, caused the refrigerant dryer to run excessively and bring about an interruption of air supply to the Instrument Air System.

The corrective actionpplanned at that time was to relocate the pressure tap to a point directly on the suction of the compressor, which would allow.back-seating of the suction valve to prevent leakage of refrigerant past its gland.

l While making a detailed study of the dryer design during the last week in May, specifically for the purpose of lo-cating a suitable place for the pressure tap, our original finding as to the prin6ipal cause of the occurrence was found to.be erroneous. Contrary to what I reported in the May 25, 1973 letter, it was found that back-seating of the compressor suction valve would not have any detrimental ef-fect on the dryer's operation whatsoever. The tap for the suction pressure controller is, and had been, properly lo-cated in the body of the valve. It appears in retrospect that the refrigerant expansion valve, which was found im-properly set during the initial investigation, actually caused the abnormal occurrence.

5760

Mr. John: F. O t:Le~ry* July 23, 1973

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In~addition to setting the refrigerant expansion valve pro-perly, which was accomplished shortly after the subject in-cident occurred, we are investigating the possibility of having a by-pass installed around the refrigerant dryers, designed to open automatically in the event that either of them causes blockage of air flow.

Our Nuclear Faeilities Safety. Committee* reviewed the cir-cumstances relating to this incident, and it has concluded that the occurrence is not one involving significant hazards considerations.

Very truly yours,