ML17252B000
| ML17252B000 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/19/1973 |
| From: | Worden W Commonwealth Edison Co |
| To: | Anthony Giambusso US Atomic Energy Commission (AEC) |
| References | |
| Download: ML17252B000 (1) | |
Text
50-249
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Commonwealth Edison* Company 72 WEST ADAMS STREET
- CHICAGO, ILLINOIS Addreu Reply fo, 60450 January 19, 1973 Mr. A. Giambusso Deputy Director for Reactor Projects Directorate of Licensing U. S. Atomic Energy Commission Washington, D. C.
20545
SUBJECT:
- LICENSE DPR~25. DRESDEN NUCIEAR POWER STATION, UNIT #3, SFCTION 6.6.B.2 OF THE TFCHNICAL SPECIFICATIONS.
Dear Mr. Giambusso:
This is to report a condition relat~ to the unit in which, on January 10, 1973, a containment spray system 1 core height inter2ock sensor was fou,n4 to be.out.side._ the.. Tec~caL.Specificat~ons.limit or Z 1
- core
- height.
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PROBLEM AND INVESTIGATION The two-thirds core height water level sensor (LITS 3-263-73A) is a Yarway serial number 24992.. The function of the sensor is to prevent use of the appropri~te containment spray system loop if the vessel water level is at or below ! core height.
- The setting found on the routine calibration
~heck performed January 10, 1973, corresponded to a level 2 inches below the J core height setting, full core height being 144 inches.
This sensor has not previously drifted more than 2 inches, remaining
.well within the band established to comply with Technical Specification: limits.
The difference between the previous instrument calibration setpoint andithe setpoint found on January 10, 1973, was seven inches.
No nuclear safety re-lated consequences resulted from this sensor setpoint change, s~e the 'inter-lock would still have operated at a vessel level equivalent to 1L.L. core height, which is still essentially j core height for all practical purposes.
CORRECTIVE ACTION 2 As stated earlier, this is the first q~c~n_9e of significant drift in the 1 core height level sensor~ The calibration surveillance frequency will be increased from quarterly to monthly until *it can be established that this instrument is not exhibiting an increasedhtendency to dP.tft.
~*~.w~,
W. P. Worden