ML20207P813
| ML20207P813 | |
| Person / Time | |
|---|---|
| Site: | General Atomics |
| Issue date: | 01/09/1987 |
| From: | Asmussen K GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 38-1006, NUDOCS 8701200272 | |
| Download: ML20207P813 (2) | |
Text
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- GATechnologies G A Technologies Inc.
PO BOX 85608 SAN DIEGo. CAUFORNIA 92138 (619) 455 3000 January 9, 1987 38-1006 gC d g/
Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Mr. Denton:
On Monday afternoon, January 5, 1987, the NRC Office of Region V was notified by telephone of a reportable occurrence concerning the Mark I reactor (R-38).
Details of the occurrence were presented at that time.
This communication is the ten-day written report required by the applicable technical specification. The details are presented below.
After termination of a customer's irradiation at 11:46 A.M. on January 5, the SAFETY rod, which was fully withdrawn during the run, did not drop when the reactor was scrammed.
Details of the subsequent observations are adequately presented by the operator'n logbook entries:
SAFETY rod did not drop.
Console power turned off.
Rod still did not drop.
Manually dropped rod.
Ran rod part way out and dropped. Ram rod completely out--did not drop.
" Determined that mesh screen which protects rod barrel from debris was too tight, binding the rod.
Screen removed and replaced more loosely."
Senior facility personnel participated in the above described series of observations, subsequent analysis, and actions.
During December 22-23, 1986, the annual fuel inspection and control rod examination was con-ducted.
After this activity, the mesh screen was positioned slightly lower than normal for these control rod barrels and that the plastic Ty-Rap (nylon tie-wrap) us.ed to secure the screen may have been applied too tightly.
On January 3, 1987, all control rods were recalibrated.
In the process of calibrating these rods, each rod was manipulated from full DOWN to full R.
The SAFETY rod dropped from full UP_.
The following Monday, January 5, the failure to drop was observed.
When the surveillance personnel replaced the mesh screen, the screen and Ty-Rap were placed a few inches lower than normal.
As a result, the dashpot piston in its uppermost position (when the rod is fully withdrawn) rested under the h
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9... j too tightly applied Ty-Rap.
By moving the mesh screen and its new Ty-Rap to a higher position, more normal position, no further binding of the dashpot piston was observed.
In the future, at the completion of the annual control rod inspection, a'-
senior facility staff member will examine the position of the rein-stalled mesh screen and the operation of each control rod, especially in -
the full E position, to assure correct installation of the protective mesh gauge.
If you have any questions concerning the above, you may call me at (619) 455-2823 or Dr. William L. Whittemore at (619) 455-3277.
Very truly yours, p
W.
N Keith E. Asmussen, M? nager Licensing, Safety and Nuclear Compliance KEA/mk cc: Mr. John B. Martin, NRC Region V Mr. A.- M. Baxter, Chairman, TRIGA Criticality Safety Committee (GA)
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