ML20084U921
| ML20084U921 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 06/06/1973 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | Kruesi F US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8306290418 | |
| Download: ML20084U921 (2) | |
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J-TENNESSEE VALLEY THOAITY j:
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Mr. F. E. Kruesi, Director
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Directorate of Regulatory Operations U.S. Atomic Energy Commission Washington, D.C.
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Dear Mr. Kruesi:
On May 7,1973, TVA notified Directorate of Regulatory Operations Region II office by telephone of what was believed to be a reportable deficiency in a cable connector at the Browns Ferry Nuclear Plant.
In accordance with paragraph 50 55(e) of 10 CFR 50, we are submitting the enclosed formal report of the deficiency.
Very truly yours,
. E. Gilleland Assistant to the Manager of Power Enclosure CC (Enclosure):
Mr. Norman C. Moseley, Director Directorate of Regulatory Operations U.S. Atomic Energy Commission Region II - Suite 818 l
q, 230 Peachtree Street, NW.
j.p Atlanta, Georgia 30303 t,.
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ENCIDSURE
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BROWNS FERRY NUCLEAR.PIANT UNIT 1 REPORTABLE DEFICIENCY - FINAL DEFICIENCY REPORT FAILURE OF CABLE CONNECTOR' E5 FOR DRYWELL BLOWER 1A4 AT PENETRATION EA l
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Dryvell blower 1At vas in service to support the Primary Contain=ent Leak Rate Test.
On May 4, 1973, a groura vas detected on 480V shutdown board 1A.
It was traced to the cotor control center (FCC) feeder co=partment for dryvell b1cuer 1A4. The source of the grourd was traced to the power leads for the dryvell blower. These power leads are routed throu:;h electrical penetration EA, connection E5-5E. Further checking showed that a 10,000-14 ohm resistance path existed fro: 3 phase to the shell of connector E5 (cable half of the connector outside the
_ _ _,dryvell). The connector in question had been potted folluving nor=al procedures. The connector was cut away
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from the cables ard was tested after heating. The resistance path was then ceasured to be 5,000 ohms. After
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cooling to a=bient te=perature, the resistance increased to 10,000 oh=s.
The pottirs co=pourd was re=oved from the connector, ard the connector was retested. The resistande path had changed
. from 10,000 oh=s to 50 megeh=s. This was measured at 500V
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DC with a portable cegger.
It was concluded that sc=e i= purity was in the connector prior to potting. After the potting co= pound was re=oved and replaced, the ano=aly no longer existed.
Since this dryvell blover is powered from an ungrounded system, no loss of function would occur from this single grouni. There are 10 dryvell bleve.rs installed, eight of which are required for continued power operation, but serve no safety function durirg a design basis accident.
In onier to assure that the other connectors for Unit 1 do not have similar defects, TVA vill conitor the grouni detectors during the preoperational and startup test a
v programs. In-service conditions vill be sufficiently severe during these programs.to ferret out those connectors c
that may have a similar defect. Future connector pottir4 vill be more closely controlled and installed in accordance with a procedure now being developed for the Browns Ferry
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Construction Quality Assurance Manual.
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