ML20140C442
| ML20140C442 | |
| Person / Time | |
|---|---|
| Site: | General Atomics |
| Issue date: | 01/21/1986 |
| From: | Asmussen K GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 67-8058, NUDOCS 8601280093 | |
| Download: ML20140C442 (2) | |
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AL OAN!A 92138 Refer To: 67-8058 (619) 455-3000 21 January 1986 Mr. Harold R. Denton Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Docket No. 50-1f3: Reactor Facility License R Information.
Dear Mr. Denton:
On December 30, 1985, the NRC Region V compliance office was notified by telephone of a December 29, 1985, occurrence concerning the R-67 TRIGA Mark F reactor. While the occurrence may not be a " reportable" occur-rence, we nevertheless want to keep you fully informed. Accordingly, the circumstances of the occurrence are described in writing herein as was suggested during the course of the subject telephone conversation.
The R-67 TRIGA Mark F reactor Technical Specification 10.2.6(g)(2) re-quires a radiation monitor capable of indicating a gross leakage of fis-sion products into the purgeable secondary containment be operable when devices having a purgeable secondary containment are irradiated in the core. This radiation monitor is referred to here as the " cell top moni-tor" and consists of a detector and associated electrical circuits and power supply. The detector is located near the top of the thermionic cells and will respond to the additional dose race produced if the pur-geable secondary containment should contain fission products.
During Mark F startup and rise to operating power on December 29, 1985, with thermionic devices having purgeable secondary containment in the core, the cell top monitor was observed to perform as expected during the initial phases of the power ascension and then it exhibited an apparent decrease in sensitivity. This apparent decrease in sensitivity was evi-denced by the monitor system showing slightly reduced readings as the power rise continued. The electronic count rate / power supply package (Eberline RM-14) was immediately replaced by a spare unit (which was kept in readiness for just such purposes) and the reading then returned to nor-mal. The Mark F logbook indicates replacement of the Eberline RM-14 unit at 1522 hours0.0176 days <br />0.423 hours <br />0.00252 weeks <br />5.79121e-4 months <br />.
Normal operation and sensitivity of the cell top monitor was verified by source checking at 1535 hours0.0178 days <br />0.426 hours <br />0.00254 weeks <br />5.840675e-4 months <br />. The estimated elapsed time during which the cell top monitor indicated reduced sensitivity was 5-10 minutes, fY 8601280093 860121
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10955 JOHN JAY HOPKINS DA, SAN DEOo, CALIFOHNIA 92121 h.
g John B.. Martin 67-8058 We trust you will find the above description satisfactory.
If you should have questions, you may contact me at (619) 455-2823 or Dr. W. L.
Whittemore at (619) 455-3277.
Very truly yours, sa 2. L Keith E. Asmussen Manager, Licensing &
Nuclear Material Control KEA:he cc: Mr. John B. Martin, NRC, Reg. V.
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