ML20114D711

Ro:On 920824,several Annunicators Re Reactor in Manual, Servo Deviation Greater than 10% & Clutch Power Off Received.Caused by Shim 3 Slipping & Clutch Current on Low Alarm.Potentiometer Wiped Clean & Current Adjusted

ML20114D711
Person / Time
Site:	National Bureau of Standards Reactor
Issue date:	09/02/1992
From:	Rowe J NATIONAL INSTITUTE OF STANDARDS & TECHNOLOGY (FORMERL
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9209090271
Download: ML20114D711 (1)

Text

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/ UNIT 3D DTATES DEPAATMENT OF COMMERCI

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%rus 3,l (301) 975-6210 FAX # 869-4770 September 2, 1992 U.S. Nuclear Regulatory Commission Attention: Document Control-Desk Washington, D.C. . 20555

Subject:

Information Letter, Docket No. 50-184 Gentlemen On August 24, 1992 with the reactor operating routinely in ,

automatic,-several annunciators were received - reactor in manual, servo aeviation greater than 10%, and clutch power off.

Reactor power decreased to about 10%. Shim No. 3 had slipped from 26* to about 21.4' r.nd its clutch current was on the low alarm.- The clutch current was reset and indicated normal. The shim was pulled back to position, but a short time later, tha same slippage occurred. The' current potentiometer was wiped clean and the-current adjusted.- However upon pulling the shim again, current monitor fluctuations were noted and as a result the reactor was shutdown.- Subsequent checking determined that chim No. 3 clutch output card was faulty. A spare card was installed and its operation was verified, after which the reactor was restarted. Since-then, reactor. operation proceeded normally.

Sincerely, J. Michael Rowe ief, Reactor Radiation Division l cct- Project Scientist L U.S.-Nuclear Regulatory Commission Region 1 475 Allendale Road.

L King of Prussia, PA 19406 Project Manager Non-Power Reactor Directorate U.S. Nuclear Regulatory Commission Washington, D.C. 20555

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