ML20236B883

Ro:On 890301,as Second to Two Std Control Rods Being Withdrawn,Other Two Rods Automatically Scrammed.Caused by Frayed Wires on Rod Drive Mechanism Resulting in Short Circuit.Electromagnetic Assembly May Be Replaced

ML20236B883
Person / Time
Site:	Kansas State University
Issue date:	03/02/1989
From:	Faw R KANSAS STATE UNIV., MANHATTAN, KS
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
NUDOCS 8903210351
Download: ML20236B883 (1)

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Department of Nuclear Engineering 1

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I 2 March 1989 '

U. S. Nuclear Regulatory Commission, Region IV 611 Ryan Pla::a Drive, Suite 1000 Arlington, TX 70011 Re: License R-68 ,

Docket 50-188 I

Dear Sina. 1 This is to report a malfunction of the drive for a standard control rod .which j took : place on 1 Mar 1989 . at the KSU TRIG A MkII . Nuclear Reactor  ;

' Facility, Reector startup was in progress after previous operation earlier in ]

the day. The safety rod was withdrawn fully and one standard rod, the I shim ' rod, .- was partically withdrawn. As the second' of two standard rods, {

the reg rod, was' being withdrawn, the other two rods were automatically {

"ectammed." . At that point,, the reg rod was manually driven into the core. l Then, with the safety and shim rods fully inserted, an attempt was made to withdraw the reg rod. The reg rod could only be partially withdrawn and automatically .was " scrammed" at approximately the same rod position that the prior shim and safety rod insertion had been triggered. A second test l revealed that the manual scram capability was not impaired and at no time was a safety system prevented from performing its function. The reactor was .

then secured and an investigation undertaken.

' Inspection of the ' reg ' rod drive mechanism revealed frayed . wires and an apparent short circuit in the . magnet-power supply line, it is our intention to remove, disassemble, inspect, and test the control-rod drive mechanism  ;

and, as necessary, to replace the -electromagnet supply line or the entire electromagnet assembly. To prevent re-occurence, we plan . to modify our procedure for biennial control rod inspection to' include inspection of the f entire rod-drive mechanism and,' as well, the console's rod-drive switch assembly. [

Sincerely, I f. .

Richard E. Faw, Director i KSU Nuclear Reactor Facility l

j! cc: Reactor Safeguards Committee i

8903210351 090302 PDR ADOCK 05000108 S PNU:

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