ML20012E066

RO 90-01:on 900228,reactor Operator Received Servo Fault Alarm.After Directed Shutdown,Complete Loss of Linear Power Channel Noted.Caused by Corroded Connector at Detector Leads.Connector Replaced.Part 21 Related

ML20012E066
Person / Time
Site:	05000128
Issue date:	03/09/1990
From:	Ives T TEXAS A&M UNIV., COLLEGE STATION, TX
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-PT21-90-038-000 90-01, 90-1, PT21-90-038-000, PT21-90-38, NUDOCS 9003300021
Download: ML20012E066 (2)

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TEX AS ENGIN EERING EXPERIM ENT STATION TEXAS ~ A&M UNIVERSITY COLLEGE STATON, TEXAS 77643 3575 l' 9 March 1990~

E NUCLEAR SCIENCE CENTEP 409/845-7551. .. ~.-w m

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'Mr. Robert D. Martin jj: hl  !:

. Regional Administrator  ! g; $lggQ i I I

U.S. Nuclear Regulatory Commission j l i

- Region' IV, 611 Ryan Plaza Drive L _

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Arlington, Texas 76011-

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Dear Mr. Martin:

I am forwarding the final report of the reportable occurrence of 28' February 1990.

This . report. is- being submitted in accordance .with the reporting requirements of Technical Specification 6.6.2 for License R-83, Texas Engineering Experiment

.. Station / Texas A&M University System.

-Respectfully,. f '

y Thomas W. Ives,, Manager

. Reactor. Operations TWI/ym Enclosure oc:' Dr. K. R. Hall, Deputy Director, TEES Dr. K. L. Peddicord, Assistant Director, TEES Dr. J. W. Poston, Head, Nuclear Engineering Mr. F. Jennings, Chairman, Reactor. Safety Board Mr. S. - H. Weiss , USNRC, Washington,- D.C.

Mr. D. E. Feltz,. Director, NSC L Dr. J. A. ' Reuscher, Director, Nuclear Research Reactor Programs, NSC Mr. B. Ernsti American Nuclear Insurers

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% Reportable Occurrence 190a01 ,

4 Failure'of Linear Power _ Channel Operation- +

as Specified in the Technical Specification

, llr DESCRIPTION- [

,t i _ . . F J On; Friday , ~ ; 28 ' February 1990, at approximately 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the reactor operator.

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received; a Servo Fault Alarm. The operator looked at- the~ linear power meter and V :noted an indication of approximately 50%. The ' Senior- Reactor- Operator soon after - -t 1 the alarm,' noticed .the : Log Channel and both Safety Channels reading Lapproximately +

. 1005.- The Senior Reactor Operator directed a shutdown and the Reactor Operator - t performed a normal shutdown of the reactor. During the shutdown a complete loss of- i E. j theLLinear Power Channel was noted. -Troubleshooting _of the Linear Channel ' began. J

? ';immediately. 'The Electronics. Technician found a corroded connector at the detector jkv leads. Ontthe sameLevening of the occurrence, the connector was replaced and. pre- ' '

d M parations were started for a power calorimetric to be performed > the. following day.

I" .The Linear ~ Channel-high v'oltage was left on overnight. The following morning, the Ldetector was not responding' properly to the decay . gammas from .the core. After f troubleshooting it was found that the -voltage connections. to the detector had been

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W reversed 'following initial; maintenance causing an . incorrect response . to the gammas 4

from the< detector. 'Arter-the leads were properly connected, the detector.' responded ~

asLexpected toithe decay gammas and the neutron source.

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SAFETY: ANALYSIS AND EVALUATION The nfailure' of the linear power channel during reactor operations resulted ? in -

U. -immediate ' action to prevent - operation of the reactor without one 'or the ' Reactor:

9 Control Systems required in' Tech Spec 3,2.1. Therefore , i this : incident falls . under

' the : reporting nreqtiirements for Reportable- Occurrences of Tech Spec _'1.29(c). As' '

soon:as itjas; determined that the channel was malfunctioning,' operations personnel commenced:aireactor shutdown. The ' loss of the linear power l measuring channel did

. - .not ? result?in? any. safety. limits = being exceeded Land all automatic safety.. systems .i

[ remained : operable throughout the incident. The corroded connector was the only . .g

. problem found in the whole Linear- Power Measuring Channel'. After,. replacement of '

- ithis connector, no other_ problems were observed. -4

. CORRECTIVE MEASURES

, Fb11owingallcorrectivemeasures,.a'. power.calorimetricwasbeguntheafternoonof' I

-1' March 1990. 00n.the morning of 2 March 1990,.the power calorimetric procedure was-s ,

completed ; satisfactory. - On Tuesday, 6 March - 1990, the night crew observed : a [

Esatisfactory Compensating: Voltage Check of the linear channel. The_. channel performedL correctly through all required checks, and ,is currently working as L well ,

, ins.-it did prior . to .this ' incident. It is obvious to the NSC . staff that the only 1

.cause of the Linear Power.ChannelcFailure was-the corroded connector,'and that the4 L NSC- operations staff can' expect reliable operation from this measuring channel.

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