ML20141H669

Monthly Operating Rept for Mar 1997 for Univ of Missouri

ML20141H669
Person / Time
Site:	University of Missouri-Columbia
Issue date:	03/31/1997
From:	MISSOURI, UNIV. OF, COLUMBIA, MO
To:
References
NUDOCS 9708010071
Download: ML20141H669 (3)

Text

,?

vcl eI,AWR ,f6 ea -

M" DBMA e-PAO J.  !

~

FILE-lyn A UNIVERSITY OF MISSOURI RESEARCH REACTOR OPERATIONS MONTHLY

SUMMARY

i 1

March 1997 Prepared by: l Operations Staff l

\

l l

\Mlllk$kNk{N[SkN,!

\

f s\s 010011 ~

9700010071 970331 PDR ADOCK 05000186 R PDR MAY 0 2 37

~

O O March 1997 The reactor operated continuously in March with the following exceptions: five shutdowns for scheduled maintenance and refueling; three unscheduled shutdowns.

On March 3, a manual rod run-in was initiated by the console operator when, for several minutes, the needle indicator remained below scale on the air plenum #1 area radiation monitor.

This monitor typically indicates in the 0.1 mR/hr to 0.3 mR/hr range while the reactor is operating at 10 megawatts. This iridication is due to a source installed inside the detector housing which prevents a false " loss of signal" failure alarm which would initiate an unwarranted reactor isolation.

Without this source, the air plenum activity is below scale on the air plenum monitor.

This monitor is one of two air plenum monitors and consists of a Geiger-Mueller type detector mounted in the containment exhaust air plenum, connected to an electronic module with indication in the control room. The air plenum electronic modules are connected to the safety system. In the event that this detector's indication reaches the alarm setpoint of 3 mR/hr, a reactor scram and isolation is initiated.

This detector model type is designed so that if a one minute lapse occurs between input pulses, the internal failure alarm relay initiater the equivalent of a high alarm, resulting in a scram / reactor isolation not attributable to high airborne radioactivity. While a below scale needle indication is not normal, and warranted a shutdown and investigation, this unit was determined to be capable of performing its safety function at the proper radiation level.

A red light emitting diode illuminates with each input pulse and can be seen at the back of the instrument, indicating that'the unit is operating. There is no mechanicallinkage between the indicating needle and the alarm setpoint--the alarm is initiated electronically, the function of which was tested satisfactorily. An electronics technician source checked, tested, and verified the satisfactory operability of the detector. The scram / isolation function was tested and operated satisfactorily. No particular cause for this downscale indication was determined and, after testing, this situation has not recurred. This detector and alarm unit was removed and its calibration checked satisfactorily on the following maintenance day.

On March 5, a rod not in contact with magnet rod run-in occurred when control blade 'B' separated from its magnet during a routine shimming evolution. The control blade drive mechanism was removed and inspected, and the guide tube alignment was checked. The specific cause could not be determined nor reproduced at the time. On March 10, a rod not in contact with magnet rod run in occurred during a normal startup, when control blade 'B' again separated from its magnet.

The reactor was suberitical at the time. The control blade drive mechanism was removed and the guide tube was realigned in order to better center the anvil seating surface. The anvil and magnet surface was cleaned. The drive mechanism was restored to normal operation. The specific cause of the magnet separation was believed to be related to the slight misalignment of the magnet / anvil within the guide tube. No further problems of this type have recurred.

Major maintenance items for the month included: shipping eight spent fuel elements to the South Carolina Savannah River Plant; installing a NUMAC rod position indication on control rod 'D' per modification package 96-2.

/-

, - ~ . - . - . - - - . - - . . - - - . . - - - . ~ . . _ . - .

O O UNSCHEDULED SHUTuGWNS j I

Date DI.m T.Y.RR C.au1R 03/03/97 1062 Manual Rod Run In ARM indication below scale 03/05/97 1063 Rod Run-In Control blade 'B' disengaged from magnet 03/10/97 1064 Rod Run In Control blade 'B' disengaged from magnet .

OPERATION

SUMMARY

HOURS OPERATED THIS PERIOD 680 TOTAL HOURS OPERATED 202,793 HOURS AT FULL POWER THIS PERIOD 676 TOTAL HOURS AT FULL POWER 199,741 INTEGRATED POWER THIS PERIOD 282 MWD TOTAL INTEGRATED POWER 77,375 MWD i

MAINTENANCE ACTIVITIES 03/03/97 Refueled - removed core 97-11, loaded core 97-12.

, 03/10/97 Refueled - removed core 97-12, loaded core 9713.

l 03/17/97 Refueled - removed core 97-13, loaded core 97-14.

i 03/24/97 Refueled - removed core 97-14, loaded core 9715.

1

+

03/31/97 Refueled - removed core 97-15, loaded core 97-16. Installed NUMAC rod position

indication on control blade 'D' per mod package 96-2.

I j

.