ML20235M471
| ML20235M471 | |
| Person / Time | |
|---|---|
| Site: | National Bureau of Standards Reactor |
| Issue date: | 09/23/1987 |
| From: | Rozier Carter NATIONAL INSTITUTE OF STANDARDS & TECHNOLOGY (FORMERL |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8710060206 | |
| Download: ML20235M471 (1) | |
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UNITED STATED DEPARTMUNT CF COMMZPC5
<j kg)h N tion:t GCurocu of t2tand:rda Geithersburg, Maryland 20899
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. September 23, 1987 L
Director, Office of Nuclear Reactor Regulation U.S. Nucicar Regulatory Commission Washington, D.C. 20555 Attn Document Control' Desk l
Gentlemen:
Subject:
Shim Arm No.i 1 Drive,' Docket No. 50-184 On September 11, 1987, while performing chim arm calibration tests at low power, it was noted tnat shim No.1 would not drive out but would drive in.
It was suspected that the clutch was slipping.
The shim arm was inserted and then withdrawn while observing the drive. The shim arm withdrew only a
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short distance beyond.the original point, however, it could' be inserted.
Subsequently,,the shim arm would not withdraw or insert and would not scram.
The reactor. was shut down, and shim arm No.1 was lowered by rotating the clutch plate by hand, in order.not' to cause any damage.
The drive was removed and the' shim arm blade was tested and it moved freely.
This confirmed that the problem wasecaused.by the drive.
The drive was disassembled ~and cleaned and two'small thrust bearings were replaced because one of the bearings appeared not--to rotate smoothly.
The drive ~was reinstalled and tested satisfactorily.
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.m Prjor to. the shim arm calibration tests, all four drives had been removed in order to' replace the' sham cadmium blade due to cadmium burnup over the last seven years of operation.
Following the blade replacement, the drives were reinstalled and tested satisfactorily.
This was followed by the calibration tests when shim arm No. 1 drive malfunctioned as indicated above.
The performance of all shims will continue to be monitored to assure that the drives are functioning properly.
Sincerely,
~MT2 -ceAa x-e Robert S. Carter Chief, Reactor Radiation Division b
8710060206 370923 ~
PDR ADOCK 05C00184 9
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