ML17037C127

Letter Regarding a Monthly Surveillance Test Where Four of the Four Triple-Low Reactor Water Level Sensors Appeared to Be Outside of the Allowable Tolerance of +/- 2.6 Inches

ML17037C127
Person / Time
Site:	Nine Mile Point
Issue date:	10/31/1972
From:	Burt P Niagara Mohawk Power Corp
To:	Skovholt D US Atomic Energy Commission (AEC)
References
Download: ML17037C127 (6)

Text

AEC -

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50-220 DESCRIPTIONS Ltr advising on 10-21-72 during surveillance monthly test. four of the four triple-low reactor water level sensors appeared to be outside allowable tlereence of +2.6 inches....

Nine Mi.le Point Unit 8' ENCLOSURES:

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MOHAWK Nine liile Point Nuclear Station Post Office Box 32

Lycoming, New York 13093 October 31, 1972 Regulatory

-File C'y.

Mr. Donald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing United States Atomic Energy Commission Washington, D. C.

20545

Dear Mr. Skovholt:

RE:

Provisional Operating License DPR-17 Docket No.: 50-220 On October 21, 1972, during a monthly surveillance test, four of the four triple-low reactor water level sensors appeared to be outside of the allowable tolerance of +2.6 inches (Article 3.6.2 of the Technical Specifications and Bases for the Nine Mile Point Nuclear Station).

Three of the four level sensors (RE18A, C,

5 D) appeared to be reading above the actual level while remaining sensor (RE18B) was reading less than the actual level.

The differential pressure type level sensors were immediately re-calibrated to be within allowable tolerance and checked out for physical damage and/or imperfections.

It was also decided to resort to a weekly test of these sensors.

During the first weekly test of October 28th, three of the four sensors were found as left.

The fourth (RE18A) was found to be outside of the allowable tolerance by about the same amount as detected on October 21, however, it was now in the opposite direction (reading less than the actual level).

The level sensor was immediately re-calibrated and examined for physical damage.

In addition, a surveillance check was repeated the following day on this level sensor.

It was found as left.

0

Mr. Donald J. Skovholt U. S. Atomic Energy Commission October 31, 1972 ileekly testing of these four sensors will be maintained during the next month.

If the sensors remain within allowable tolerance during this period, monthly testing will be resumed.

Furthermore, a careful review of present testing procedures for these devices is underway.

Very truly yours, P. Allister Burt General Superintendent Nuclear Generation

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