ML20136H329

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Ro:On 851112,wide-range Log Channel Malfunctioned During Operation of Reactor.Caused by Faulty Calibr Switch in Log Channel.Switch Adjusted & Reactor Operated at Several Power Levels Up to 95 Kw
ML20136H329
Person / Time
Site: Dow Chemical Company
Issue date: 11/13/1985
From: Kocher C
DOW CHEMICAL CO.
To: James Keppler
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 8511250086
Download: ML20136H329 (2)


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November 13, 1985 MICHIGAN DIVIStoN MIDLANo, MICHIGAN 48640 PRIC1ITY ROUTING

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M, /Np 799 Roosevelt Road FILE w Glen Ellyn, Illinois 60137 MALFUNCTION OF THE WIDE-RANGE LOG CHANNEL DURING OPERATION OF THE DOW TRlGA RESEARCH REACTOR On Tuesday, November 12, 1985, at about 10:18 A.M., Senior Reactor Operator T. J. Quinn was taking the TRIGA reactor to a power level of 95 kw. As this was the first operation of the day, Mr. Quinn first i performed the daily checkout and then measured the core excess at a power level of 5 watts. As this core excess was correct for the current 3 configuration of the TRIGA reactor, Mr. Quinn then initiated the rise of power to the desired level by pulling the shim rod while watching the period meter and the log power and linear power recorder traces. Within a few seconds he observed the period meter indicate that the period was decreasing, the log power recorder trace indicate that the power was leveling off at about 12 watts, and the linear power recorder trace indicate that the power level continued to rise. Mr. Quinn initiated a manual scram and secured the reactor. He then notified the reactor supervisor. A meeting of the Reactor Operations Committee, consisting of D. L. Berry, Chairman, W. L. Rigot, Assistant Reactor Supervisor, (

C. W. Kocher, Reactor Supervisor, and H. W. Emmel, Senior Reactor Operator, was called. The events were reviewed and compared with the events of about 11 months ago, which were strikingly similar. It was decided to check some of the circuits in the log channel and then to restart the reactor. Mr. Knicely of the Region III office of the U. S.

Nuclear Regulatory Commission was notified by telephone shortly after 3:00 P.M. the same day.

The ' calibrate' switch in the log channel was found to be at fault.

After a discussion with a representative of the manufacturer the switch was adjusted and the reactor was operated at several power levels up to 95 kw to check the operation of the log channel and to compare the log 0511250086 851113 PDR ADOCK 05000264 S PDR I

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u-t', ^ s e t' J. G. Keppler November 13, 1985 Page 2 channel calibration with the linear channel. The log channel was found to operate over the range of interest and to agree with the readings of the linear channel. The reactor was returned to service.

CU /6' O. W. Kocher Reactor Supervisor Analytical Laboratories 1602 Building cc: D. L. Berry, Chairman Reactor Operations Committee The Dow Chemical Company 1602 Building Midland, Michigan 48674 L. W. Rampy, Chairman Radiation Safety Committee The Dow Chemical Company Midland, Michigan 48674 kf l

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