ML19338D626

Discusses Deviation from Tech Specs 3.6,requiring Samples in Ctr Test Hole to Hold Rigidly in Place During Reactor Operation.Review of Importance of Visual Verification of Sample Loadings Conducted W/Entire Operating Staff

ML19338D626
Person / Time
Site:	University of Missouri-Columbia
Issue date:	09/18/1980
From:	Brugger R, Mckibben J MISSOURI, UNIV. OF, COLUMBIA, MO
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8009230586
Download: ML19338D626 (3)

Text

Research Reactor Facility UNIVERSITY OF MISSOURI Research Park Co!urnbia. Missouri 6s211 September 18, 1980 Telephone Q14) 8224211 Director of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Reference:

Docket 50-186 University of Missouri License R-103

Subject:

Report as required by MURR Techrical Specification 6.1.h(2)

Descriction On Augst 21, 1980, the reactor was started up following a routine sample change out of the flux trac region and run for a period of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 13 min-utes with 1 incn of free space in tube B of the flux trap located in the center test hole region. This Jermitted the remaining 29 inches of samples a free volume for rovement. This was a deviation from Technical Specification 3.6 requiring samoles in the center test hole to be held rigidly in place during reactor operacion.

Analysis The center test hole at the University of Missouri Research Reactor is a Sgh flux region used for the irradiation of samples of a 1 inch diameter and lengths varying from 2 to 5 inches held in place by the flux trap. The flux trap is made of three 1 inch diameter tubes welded in a triangular arrangement with a total vertical sample profile of 30 inches. During reactor operations, a three-pronged hold down device is pinned in place preventing vertical move-ment of the samples.

On August 15,1980 at 0515, a regularly scheduled sample handling shut-down occurred. Samples were changed in all three tubes of the flux trap. A required visual loading verifica+ ion was cmitted during the sample change out evolution because of operator error. The loading verification consists of raising the unloading device to the proper height and visually confirming that the top of the uppermost sample can is aligned with the unloading door. This O

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4 Director of Licensing September 18, 1980 Page 2 verification was instituted due to an incident reported to the Nuclear Regulatory Commission in a letter dated July 7,1980.

At 0600 samples removed from the flux trap were placed in a cask and transported to an exterior hot cell for processing. At 0640 the personnel processing the samples infomed the control room that an error had been made in the sample change out process. At 0643 the reactor was shutdown. Sample cans labeled 1 and 4 had been confused due to being poorly marked and sample number 4, a 3-1/2 inch sample ,

can, was removed instead of sample number 1, a 2-1/2 inch can. These {

sample cans are identified by engraving a number on the aluminum sur-face of the top and bottom of the cans. The sample cans involved in the incident had been engraved by a new employee and were not easily distinguished. The combination of the confused numbers and the omission l of the loading verification resulted in the reactor being operated with-out the samples in the center test hole being rigidly held in place.

No unreviewed safety question existed during this period of oper-ation. The reactivity of all samples in the center test hole region 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 l

tube so that the inch of free space shifted, the effect would have been less than 2 cents of reactivity change. A review of nuclear in-strumentation recorder charts for the period in question show no variance in reactor power which would have resulted if the samphs shifted during critical operation. Additionally, the pool cooling system directs a downward ficw through the center test hole region helping to prevent the upward movement of samples.

Corrective Action A review of the importance of the visual verification of sample loadings in the center test hole region was conducted with the entire operating staff. Personal interviews were also conducted with the op-erators who had conducted this particular evolution emphasizing the significance of their error; also their responsibilities and importance of their job were emphasized.

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! o i Director of Licensing September 18, 1980 Page 3 Additionally, a standard method has been institute d for formation of the numerals used to identify sample cans to elimini.te the source of the confusion of the numbering.

Sincerelv, Y

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J. C. McKibben

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Reactor Manager Endorsement Reviewed and approved g

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R. M. Brugger Director JCMK:vs N

cc: U.S. fluclear Regulat::ry Commission c/o Document Management Branch James Keppler, Director Regulatory Operations - Region III Roactor Advisory Connittee Reactor Safety Ccnaittee

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