ML20244A740

Ro:On 890317,reactor Trip W/High Primary Coolant Temp Indication Occurred.Caused by Failure of Specific Temp Recorder Sys Due to Dust/Corrosion Buildup on Slide Wire Causing Excessive Resistance.Buildup Cleaned Off

ML20244A740
Person / Time
Site:	05000083
Issue date:	03/31/1989
From:	Vernetson W FLORIDA, UNIV. OF, GAINESVILLE, FL
To:	Ernst M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 8904180168
Download: ML20244A740 (2)

Text

-. _. _ _ _ _ _ . __ . _ _ _

NUCLEAR EN2iNEERIND SCIENCES DEPARTMENT Nuclear Reactor Facility l University of Florido l ca.vem.i.on, omciar .

! meuunwo.uw,s -

i s ~- mm 39a,PR6 A9 .

51

[. Phone (904)392 M29.Teles56330 March 31, 1989 Final 14 Day Report:

Trip on High PC Temperature <

Indication Due to Monitoring System Failure l

Nuclear Regulatory Commission, Region II 101 Marietta Street, N.W.

Suite 2900 Atlanta, GA 30323 Attention: Mi.colm L. Ernst Acting Regional Administrator, Region II RE: Universi.ty of Florida Training Reactor Facility License: R-56, Docket No. 50-83 SCENARIO On Friday, March 17, 1989 the University of Florida Training Reactor (UFTR) was started up at 1038 hrs; at 1836, hours af ter approximately 7-hours of sample irradiation at full power (supporting neutron activation analysis),, the reactor tripped with a high primary coolant temperature indication. The SRO on call (P.M. Whaley) was in the reactor cell conducting radiation surveys and responded immediately to assist in evaluation and response to the occurrence. The reactor operator (Mike Wachtel) at the controls responded promptly to shut down and secure the reactor at 1837 hours0.0213 days <br />0.51 hours <br />0.00304 weeks <br />6.989785e-4 months <br />.

Since the trip indicator was high primary coolant temperature, the temperature recorder was left in operation following the trip event. In this way the RO and SR0 were able to observe indications that the cooldown was normal with no one fuel box outlet temperature significantly higher or lower than the group; this data indicates normal flow. The trip itself was noted to have occurred on fuel box temperature #6, not f uel box #1, so the recording instrument did not start to drive to that point f rom very f ar down scale which could have resulted in an overdrive to give a trip. It was also noted that there was no trend on the temperature prior to the trip as one point printing indication was slightly high that the and trip the next jumped occurred over 10 F at an indicated to cause the temperature trip. Finally, of about 151.5 Fit which was noted,Fis 3.5 below the nominal limiging safety system (trip) setting of 155 F. The audible warning alarm set at 150 F was also noted to occur.

qe r deys]k+

$8421sI*n s Sh3 --~

P DM s(

qlu tp uWu oa u ~ 3nor p

i I *.

b i ,.

Malcolm L. Ernst March 31, 1989 Page 2 This entire scenario as well as readiness to restart was communicated to Mr.

Paul Frederickson (Region II NRC) on March 21, 1989 after initial attempts at telephone communication were unsuccessful on March 20, 1989 due to problems with i the Region II telephone system.

EVALUATION / CORRECTIVE ACTION Under Maintenance Log Page #89-18, the specific temperature recorder system failure has been determined to be dust / corrosion buildup on the slide wire  ;

which caused excessive resistance and drift of the indicator upscale through the upscale burnout feature. This dust / corrosion buildup was cleaned off and the temperature recorder was checked out to assure proper response. The required teactor systems were then checked out with restart confirming proper operation on March 21, 1989.

To prevent recurrence of this event, further corrective action is being instituted as a standard maintenance action to require cleaning the temperature recorder slidewire and associated recorder connections and contacts quarterly at intervals not to exceed four (4) months as part of the Q-1 Surveillance.

CONSEQUENCES .

l The Reactor Safety Review Subcommittee (RSRS) Executive Committee met on March 20, 1989 and agreed with the trip evaluation and that it was probably not promptly reportable but that it should be reported anyway in conjunction with a report on a "f ailure to post a radiation area". The committee authorized .

restart for normal operations upon successful completion of the temperature j recorder repair. The full RSRS was updated on the occurrence at its regularly I scheduled meeting on Tuesday, March 21, 1989 where all members were in attendance. ]

Reactor staf f and administration including Director W. G. Vernetson present on l Friday, March 17, 1989 agreed there was no compromise to reactor safety in this I event, nor was there danger of personnel receiving excessive radiation doses. l All other reactor safety review and control systems responded properly. l l

If further information is needed, please advise.

Sincerely,

~

i k>utbc.u_ v William G. Vernetson

(' Notary P 4 blic Director of Nuclear Facilities cc: P.M. Whaley Reactor Safety Review Subcommittee Document Control Desk

_ _ _ _ _ - _ _ - _ _ _ _ _ _ _ - _ _ _ - _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ - - _ -