ML20084U869
| ML20084U869 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 06/01/1973 |
| From: | Gerald Williams TENNESSEE VALLEY AUTHORITY |
| To: | Kruesi F US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084U431 | List: |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8306290339 | |
| Download: ML20084U869 (1) | |
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anreateu PARTN C A15 Hip June b.,1973 k/ hk
- d $f Mr. F. E. Krucci, Director
.Dir.cctorcte of.Eccule.tery.,0perations U.S. Atomic Energy Commission Washington, DC 20545
Dear Mr. Kruesi:
On May 3,1973, TVA made initial report to AEC-DRO Inspector W. S. Little of the failure of a channel A Traveling Incore Probe (TIP) cable and detector at Browns Ferry Nuclear Plant unit 1.
In accordance with paragraph 50.55(e) of 10 CFR 50, we are sutuitting the enclosed formal interim report of the failure. We expect to submit the final report by July 10, 1973.
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Godwin Williams, Jr.
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Assistant Mana6er of Pover' Enclosure CC (Enclosure):
Mr. Norman C. Moseley, Director Directorate of Regulatory Operations U.S. Atomic Energy Co= mission Region II - Suite 818 230 Peachtree Street, NW.
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. Brevns Ferry Nuclear Plant Unit 1 Deficiency Report; l
CHAICEL A TIp FAILURE L
On the morning of May 2,1973, TIP machine A drive cable and detector were fot'nd da= aged. The detector had been severed from the cable.
i It is believed that operation of channel A and 3 of the TIP system was initiated manually from the unit I control room. At that time the containment was pressurized to 49 psig during GE No.14 test of the integrated leakage rate.then in,, progress. Operation of a-TIP, channel requires that a ball valve be open in the guide tube to the drywell.
Apparently the containment pressure was applied down the guide tube containing the probe through the open ball valve to the operating mechanism J
of the chamber shield -limit switch. This limit switch nor= ally' stops further withdrawal when the detector on the end of the TIP cabic is withdrawn past the switch operating mechanism and through the shicid. Design of the limit switch operating mechanism, however, would allow the pressure to hold the mechanism against the switch actuator button and prevent detection of further P
withdrawal. Failure of the shield liuit switch to stop the drive nechanism appears to have allowed the channel A detector to be pulled.into the drive mechanism where the drive gear probably severed the cable. The channel B detector was pulled past its shield limit switch but did not enter its drive unit.
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TVA and CE are in the prccess of determining the safety implications of this failure and the corrective measures required. A final report on this failure is expected to be submitted by July 10, 1973.
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