ML20206B993
| ML20206B993 | |
| Person / Time | |
|---|---|
| Site: | University of Missouri-Columbia |
| Issue date: | 10/31/1988 |
| From: | Brugger R, Mckibben J MISSOURI, UNIV. OF, COLUMBIA, MO |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8811160067 | |
| Download: ML20206B993 (2) | |
Text
October 31, 1988 Research Reactor Facility UNIVERSITY OF MISSOUni g,,e,,t, p,,,
Colvtb.a M ssoon 65211 Te'epN>ne (314) 882-4211 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail. Station P1-137 Washington, D. C.
20555
REFERENCE:
Docket 50-186, University of Missouri Research Reactor License R-103
SUBJECT:
Revision to a Report as required by Technical Specification 6.1.h(2) concerning reactor operation with the regulating blade inoperable.
Dear Sir:
The University of Missouri Research Reactor submitted a report as required by Technical Specification 6.1.h(2) dated October 19, 1988.
In routing that letter for review within the facility, it has been brought to my attention that the second sentence in the letter could be read and interpreted with an erroneous meaning.
Therefore, I have attached a revised first page to that letter with the revision lines marked with a bracket (]) in the right margin.
Hopefully, this will alleviate any concerns due to an unintended interpretation of the first paragraph in the October 19, 1988 letter.
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REV! SED Research Reactor Facility UNIVERSITY OF MISSOURI October 31, 1988 co'et,.tO.*Eo'[es/il Te'ephone 0 14) 882-4211 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Station P1-137 Washington, D. C.
20555
REFERENCE:
Docket 50-186, University of Missouri Research Reactor License R-103
SUBJECT:
Report as required by Technical Specification 6.1.h(2) concerning reactor operation with the regulating blade inoperable.
1 DESCRIPTION:
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At 1145 on September 21, 1988 with tht reactor operating at full power in the automatic mode, a channel 4 high power rod run-in occurred.
The duty operator reset the rod run-in and recovered to full power.
When he determined that the regulating
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blade would not respond in either the automatic or manual mode, the reactor was
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shutdown by manual rod run-in to repair liie regulating blade drive system.
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Preceding the failure, the reactor had been in continuous full power operation with the regulating blade properly maintaining power in automatic control for a period of 129 hours0.00149 days <br />0.0358 hours <br />2.132936e-4 weeks <br />4.90845e-5 months <br /> 45 minutes.
The operability prior to the the failure was veri-fled by review of Operations logs and the wide range monitor chart indication.
The reguleting blade indication was observed changing by the duty operator shortly before the channel 4 high power rod run-in.
The reactor was shutdown to be in accordance with Technical Specification 3.2.a which states "all control blades, including the regulating blade, shall be operable during reactor operation."
ANALYSIS:
The regulating blade controls reactor power at a desired level set by the duty operator (normally 10 MW). The blade is constructed of stairiless steel and drives at 40 inches per minute.
The regulating blade drive mechanism lead screw translates rotary motion of the drive motor and gear box into linear motion of the regulating blade.
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