ML20085M639
| ML20085M639 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/28/1973 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085M634 | List: |
| References | |
| AO-BFAO-7343W, NUDOCS 8311090120 | |
| Download: ML20085M639 (2) | |
Text
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m TENNESSEE VALLEY AUTHO AITY C-1K' /,-
CHATTANOOGA, TENNESSEE 37401
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November 28, 1973 50-259 an nss
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Mr. John F. O'Ieary, Director Directorate of Licensing Office of Regulation U.S. Atomic Energy Commission Washin6 ton, DC 20545
Dear Mr. O'Ieary:
TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCLEAR PLANT UNIT 1 -
DOCKET NO. 50-259 - FACILITY OPERATING LICENSE DPR ABNOMAL OCCURRENCE REPORT BFAO-7343W The enclosed report is to provide details concerning si nificant 6
vibration in torus and torus-ring header upon opening relief valves during startup testing which occurred on Browns Ferry Nuclear Plant unit 1 on November 18, 1973, and is submitted in accordance with A,pendix A to Regulatory Guide 1.16, Revision 1, October 1973 1
Very truly yours, TENNESSEE VALLEY AUTHORITY 4I b
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Mr. Norman C. Moseley, Director
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Region II Regulatory Operations Office, USAEC 230 Peachtree Street, NW.
Atlanta, Georgia 30303
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ABNORMAL OCCURRENCE REPORT Report No.: BFAO-7343W Report Date:
November 28, 1973 Occurrence Date:
November 18, 1973 Facility: Browns Ferry Nuclear Plant Identification of Occurrence Significant vibration in torus and torus-ring header upon opening relief valves during startup testing of unit 1.
Conditions Prior to Occurrence The reactor was at approximately 35-percent power during the startup test program.
Description of Occurrence During testing of relief valves on November 8, significant noise was heard emanating frca the torus and dryvell when the relief valves were opened. The noise associated with two valves was significantly greater than from the others.
On November 11, a dryvell and torus entry was made to inspect for possible change; none was found but it was noted that one relief valve discharge pipe had vibrated against floor grating within the dryvell. Clearances were increased to eliminate this interference.
On November 18, with spscial instrumentation installed on the torus to measure acceleration and deficction, the relief valves were again opened. The deflection h
measured was more than desirable but still within the range predicted by General Electric Co=pany. During these tests, it was noted that three torus support feet vere not in full contact with their support pads. At this time, the conditions were reported as an abnormal occurrence.
Desisenation of Anparent Cause of Occurrence i
Torus vibration as a result of relief operation is an expected phenomenon.
However, during inspection on November 19, it was discovered that nine torus support saddle feet were not in full contact with their support pads. Lack of contact may be the cause of the excessive vibration. Continued inspection is being conducted.
Corrective Action The space between the torus support saddle feet and the support pads
- vill be shimmad as necessary to ensure proper contact and support for the torus. Additional.
g vibration testing vill be performed following this corrective work.
The design fix arrived at for unit 1 vill also be applied to units 2 and 3 Sii?2