ML20090E125

RO-84-4:on 840626,reactor Operator Noted That Fuel Element Temp Recorder Did Not Correspond to Digital Indication as Shown on Doric Temp Readout.Cause Not Stated.Failure Spurious & Could Not Be Reproduced

ML20090E125
Person / Time
Site:	05000128
Issue date:	07/02/1984
From:	Willits B TEXAS A&M UNIV., COLLEGE STATION, TX
To:	Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
RO-84-4, NUDOCS 8407190300
Download: ML20090E125 (3)

Text

a TEXAS ENGINEERING EXPERIMENT STATION 9$

THE TEXAS A&M UNIVERSITY SYSTEM

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COLLEGE STATION. TEXAS 77843-3575 1  !

2 July 1984 NUCLEAR SCIENCE CENTER 409/845-7551 Mr. E. Johnson Office of Inspection and Enforcement $@$$@ b' Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Driva, Suite 1000 M 10 m Arlington, Texas 76012 -

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Dear Mr. Johnson:

l I am forwarding the final report of the reportable occurrence of 26 June 1984. This report is being submitted in accordance with NSC Technical Speci-J fication requirements Section 6.6.2 of the Nuclear Science Center Reactor, License R-83, Texas A&M University.

Respectfully, S

BarryyWil its, Managerxa3 hit.

Reactor Operations BW/ym Enclosure 8407190300 840702 PDR ADOCK 05000128 S PDR CJ

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RESEARCH AND DEVELOPMENT FOR MANKIND i__

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Reportable Occurrence #84-4 Failure of Reactor Safety System

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Channel During Reactor Operation

! Reportable Occurrence-I- !0n.26 June 1984 at 1312 during normal reactor operation, the Reactor Operator noted that the Fuel Element Temperature recorder did not correspond to the

digital indication as shown on the DORIC temperature readout. Reactor power t

had been returned to 950 kw at 1310 following a brief reduction in power E .to load an experiment. The digital temperature for the fuel element thermo-couple #2 indicated 694.4*F (approximately the same reading prior to the transient) yet the temperature recorder indicated approximately 565'F. The

-operator immediately informed the Senior Reactor Operator and Manager of

. Reactor Operations of tha apparent abnormality. The Fuel Element Temperature recorder is hard-wired to monitor thermocouple #2 of the operational Instru-i mented Fuel Element, and the digital instrument (D0RIC) can be selected to  !

read thermocouple #1 or #2.- The digital thermocouple. instrument was selected to thermocouple #1 which indicated a temperature consistent with the digital reading of thermocouple #2. The operator observed proper response and indi-1 cation on all other reactor power level indication consistent with both digital thermocouple readings. A visual check of the temperature recorder showed i no apparent binding of the pen or drive mechanism, or any obvious cause for the improper response. At 1313.a reactor shutdown was commenced in accordance with S0P III-B, while closely monitoring the digital thermocouple instrument p and reactor power level instruments in addition to the Fuel Element Temperature

recorder. All indication, with the exception of the fuel temperature recorder, responded normally. The recorder reading remained at the original indication of 565'F du' ring the shutdown.

4 Corrective Action i

Following the' shutdown, initial troubleshooting-of the recorder caused the pen movement to begin functioning correctly when a slight pressure was applied i to the'slidewire.potentiomet.er control cable.- It should also be 'noted that

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the chart recorder showed the instrument tracked the initial down power ma-neuver to load _the experiment. Then when reactor power was increased, the recorder trace showed a normal increase from approximately 450*F until it

-suddenly stopped at about 565'F. Subsequent troubleshooting failed to dupli-cate the problem, and an operational check of the recorder was performed ,

satisfactorily. :An additional check-of the; instrument consisting of the ~

applicable portion of the Prestartup Checklist,.was made to verify that the  !

LSSS scram was functioning. NSC management concluded that the fuel element temperature recorder was functioning correctly and that the-failure was spu-rious and could not be reproduced, i

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A reactor startup was commenced while closely observing the temperature re-

. corder and the digital thermocouple indication. The recorder responded nor-mally, and at 1458 reactor power was stabilized at 950 kw. At this point normal reactor operation was resumed. Subsequent reactor operation has re-sulted in no recurrence of the temperature recorder failure, although the instrument is being closely monitored during reactor startups and power tran-sients. NSC management in review of the reportable occurrence has determined that the operators acted promptly and in accordance with approved S0P's.

The temperature recorder faile!re was a spurious occurrence and that at no point.during the incident was an operational power limit or safety limit exceeded.

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