ML20198P254

Ro:On 971104,change of Mode Switch from Manual to Pulse Positions Did Not Reliably Switch Between Normal & High Range Signals.Caused by Malfunction of Switch.Applied Switch Cleaning Fluid to Switch

ML20198P254
Person / Time
Site:	05000113
Issue date:	11/05/1997
From:	Williams J ARIZONA, UNIV. OF, TUCSON, AZ
To:	Mendonca M NRC
References
NUDOCS 9711070040
Download: ML20198P254 (2)

Text

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t4UCLE AR Et4 Git 4EERIl4G TEL1520-621-8096 tiov 05.97 14: 18 No.003 P.01 j'b - //1 l

Date: 5 Nov 1997 To: Attention of Marvin Mendonca, By Telefax,(301) 415 3313, USNRC, One White Filnt North 11555 Rockville Pike Rockvlile, MD 20852 2738.

From: John O. Willinmn, Re .: tor Laboratory Director, Engineering Building 20, University of Arizona, Tucson, AZ 857210020 (620) 621 9729 Ret Reportable occunence, trar.smitted within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

The occurrence documented on the following page was reported by telephone to you at 1345, local time, today. Mr. Steven Holmes' meunge system also received my call.

The tequired telegraphic report is submitted via telefax herewith, for recording on our License Docket. A fuller written report will follow within 10 days.

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_. _ _ _. _ _ _ .m HUCLEGR ENGINEERING R EL:520-621-8096 Nov 05.97 14: 10 tio.003 P.02 FACILITY I,1CP.NSE R 52 t ,

Malfunction of Mode Switch in Pulse Mode i

Prcliminary Report. November 5,1997

O'i November 4,1997, a pulse was performed with the mode switch in its Pulse High I netting and with the transient rod anvil net for a $1.75 pulse. De transient rod operated normally, fuel temperature rise was recorded showing energy deposition in the range r

, expected for a normal pulse and the timer scram operated normally. No valid indk.ation '

appeared, however, for the peak tenctor power or the Integrated pulse energy. %e right ,

safety channel lndicated a trip on reactor power.  :

A digital data acquisition system connected to the right safety channel showed that the algnal on that channel dispinyed a normal reactor perlod of approximately 11 ms, but then  !

saturated. This showed that the channel was connected to a valid Indicatlou of reactor 1

[ power level from the km chamber that is normally connected in steady state mode, not the j high range ion chamber which should be selected in pulse mode. De trip on the right

bafety channel was attributed to power in excess of 110 kW, which is the s'cady state limit.

Testing of the mode switch revealed that changing the switch from its manual to pulse positions did not rcilably switch between the normal and high range alsnals. De problem

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was corrected by app!kation of switch cleaning fluid. After this w as done the system appeared to behave normally. He reactor was then operated at 95 kW steady state while i the high range channel was calibrated and shown to behave normally.- A pulse was then -

performed and normal indications were found on all channels.

A malfunction of the mode switch was the cause, it resulted in failure to pick a relay

which switches from the normal to the high range channel when pulse mode is selected, and which also switches in the nyt circuitry that indicates integrated pulse energy. The system failed safe caum. 4.ictuation of reactor scram at 110 kW. He reactor did not operate outside its normal envelope, and there was no threat to health or safety of the public, f.f J. O. Williams. Reacer laboratory Director ,

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