ML20236B883

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Ro:On 890301,as Second to Two Std Control Rods Being Withdrawn,Other Two Rods Automatically Scrammed.Caused by Frayed Wires on Rod Drive Mechanism Resulting in Short Circuit.Electromagnetic Assembly May Be Replaced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


Text

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3 @' @ {R UN8 [S T wa - 61989]l

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- g '1 Department of Nuclear Engineering

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3GlQqEAS Ward Hall h.;

ansas N N

9 3h"f, UNIVECRSITY 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The safety rod was withdrawn fully and one standard rod, the I

shim ' rod,.- was partically withdrawn.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,

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the reg rod, was' being withdrawn, the other two rods were automatically

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"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 The reg rod could only be partially withdrawn and automatically.was " scrammed" at approximately the same rod position that the prior shim and safety rod insertion had been triggered.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 or the entire and, as necessary, to replace the -electromagnet supply line 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.

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Sincerely, I

f..

Richard E. Faw, Director KSU Nuclear Reactor Facility i

l cc: Reactor Safeguards Committee j!

i 8903210351 090302 PDR ADOCK 05000108 S

PNU:

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