ML19320B495

Ro:On 800616,while Verifying Sample Loading of triple-tubed Sample Irradiated Facility Located in Ctr Test Hole,One Tube Was Found Missing 2-inch Long Spacer.No Unreviewed Safety Question Existed During Period of Operation

ML19320B495
Person / Time
Site:	University of Missouri-Columbia
Issue date:	07/07/1980
From:	Alger D, Mckibben J MISSOURI, UNIV. OF, COLUMBIA, MO
To:
References
NUDOCS 8007140351
Download: ML19320B495 (2)

Text

Research Reactor Facility UNIVERSITY OF MISSOURI Research Park Columbia, Missouri 65211 July 7, 1980 TPhoa* (3:4)882-421 Director of Nuclear Reactor Regulations U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Reference:

Docket 50-186 University of Missouri License R-103 Description On June 16, 1980 during a scheduled maintenance shutdown, it was determined while verifying the sample loading of the triple-tubed sample irradiation facility located in the center test hole; that one tube 1:as missing a 2 inch long spacer. Therefore, the remaining 28 inches of saraples and spacers had 2 inches of free space. This was in violation of Technical Specification 3.6.e requiring samples in the center test hole to be rigidly held in place during reactor operation.

Analysis The center test hole at the University of Missouri Research Reactor is a high flux region used for the irradiation of samples of 1 inch di-ameter and lengths varying from 2 to 5 inches. Three 1 inch diameter tubes are banded together in a triangular arrangement with a total ver-tical profile of 30 inches. During reactor operations, a three-pronged hold down device is pinned in place preventing vertical movement of the samples.

On June 16, 1980, when the operating crew unloaded tube A to verify the loading, it was determined that a 2 inch spacer had been left out. ,

The last sample change evolution had occurred at 0515 on June 15, 1980 l during a scheduled shutdown for that purpose. The reactor was started I

, up at 0525 on June 15, 1980, and operated continuously till the scheduled i shutdown for the maintenance day at 0400 on June 16, 1980; during this shutdown the discrepancy was discovered. The reactor was operated with tube "A" samples not held rigidly in place for 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> and 35 minutes.

[0M s l

g 8y,v //O h[f COLUMBIA KANSAS CITY ROLLA ST. LOUIS 8007140 0 "y'* " ' ** "'""' '"""$

Direct:r of Nuclear Reactor Rsgulations

< July 7,1980 Page 2 No unreviewed safety question existed during this period of oper-ation. The reactivity of all samples in the flux trap is restricted by Technical Specification 3.1.h to less than that which could cause fuel element failure. If the samples had moved up in the tube so that the two inch free space was on the bottom, the effect would have been . .,

less than five cents worth of reactivity change. Additionally, the pool cooling system directs a downward flow of coolant through the center test hole region, which helps prevent the upward movement of the samples. A review of nuclear instrumentation recorder charts for the period in question shows no variances in reactor power which would have existed if the samples had shifted during critical operation.

Corrective Action The rod used for unloading the flux trap has been marked so that it will be used to verify the sample region has been properly reloaded with 30 inches of samples and/or spacers. Additionally, the sample loading sheets will be verified to insure proper loading prior to and following the evolution.

Sincerel , -

f.

w

g. .

~

J. C. McKibben Reactor Manager e e and approved %h, Don M. Alger Associate Director JCMK:vs '

cc: U. S. Nuclear Regulatory Commission c/o Document Management Branch James Keppler, Director Regulatory Operations - Region III Reactor Advisory Committee Reactor Safety Subcommittee

.