ML20101M849

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Ro:On 841203,wide-range Log Channel Malfunctioned,Resulting in Manual Scram.Cause Traced to Resistor in Filter on Detector High Voltage Supply.Repairs & Testing in Progress
ML20101M849
Person / Time
Site: Dow Chemical Company
Issue date: 12/10/1984
From: Kocher C
DOW CHEMICAL CO.
To: James Keppler
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 8501030275
Download: ML20101M849 (1)


Text

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December 10, 1984 ,,ot,so, u,cg,a,y 4,34, J. G. Keppler

, United States Nuclear Regulatory Commission Region III

.799 Roosevelt Road Glen'Ellyn, Illinois 60137 MALFUNCTION OF THE WIDE-RANGE LOG CHANNEL DURING OPERATION OF THE DOW TRIGA RESEARCH REACTOR c-On Monday, December 3, 1984, at about 2:40 P.M., Senior Reactor Operator T. J. Quinn was taking the TRIGA to a power level of 95 KW. As this war.

the first operation of the day, Mr. Quinn first took the reactor to a steady-state power level of 5 watts for a measurement of the core excess, which he found to be correct for the current configuration of the TRIGA.

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, while at the same time the log power trace was levelling off and the linear power trace continued to rise.

At this point Mr. Quinn initiated a manual scram and secured the reactor.

He discussed this event with Ward Rigot, the Assistant Reactor Supervisor.

They concluded that the wide-range log channel had malfunctioned, possibly in the Campbell circuitry. Mr. Rigot reported this to me as I returned to the building some fifteen minutes later. I reviewed the experience and the recorder tracings with Mr. Quinn and determined that a malfunction had occurred. I notified D. L. Berry, Research Manager and chairman of the Reactor Operations Committee and telephoned Mr. Kenneth Ridgeway at Region III, U.S.N.R.C., shortly'after 3:30 P.M. that day.

Subsequent investigation and consultation with the manufacturer indicated that the cause might be traced to a particular resistor in a filter on the detector high-voltage supply. Repairs and testing are in progress.

(,u) /(oL 3 C. W. Kocher Reactor Supervisor Analytical Laboratories 1602 Building cc: D. L. Berry, Chairman L. W. Rampy, Chairmen Reactor Operations Committee Radiation Safety Committee "he Dow Chemical Co.

i The Dow Chemical Co.

1602 Building 1803 Building Midland, MI 48640 Midland, MI 48640 lb B501030275 841210 PDR ADDCK 05000264 S PDR AN OPERAMG UNIT oF THE DOW CHEMICAL. COMPANY g Ife?