ML20062H008
| ML20062H008 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 08/06/1982 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-82 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8208130263 | |
| Download: ML20062H008 (2) | |
Text
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..'^- A U w.I TENNESSEE VALLEY AUTHORITY
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CHATTANODGA', TENNE %SEE 37401 00 Chestnut Street' Tower II A/O.Agyst6,1982 (p-4$$
U.S. Nuclear Regulatory commission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street,' Suite 3100 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNIT 1 - EXCESSIVE VIBRATIONS OF ERCW PUMP / MOTOR -
NCR 1249 - SECOND REVISED FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector F. S. Cantrell on August 19, 1980 in accordance with 10 CFR 50.55(e).
This was followed by our interim reports dated September 17 and December 2, 1980, our final report dated February 4,1981, and our revised final report dated September 8, 1981. As discussed with E. H. Girard by telephone on July 23, 1982, enclosed is our second revised final report. The reason for this revision is to provide additional information to clarify the report.
We consider 10 CFR Part 21 applicable to this deficiency.
If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY
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L.
M.' Mills, Manager i
Nuclear Licensing Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission Washington, DC 20555 i
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ENCLOSURE BELLEFONTE NUCLEAR PLANT UNIT 1 EXCESSIVE VIBRATIONS OF ERCW PUMP / MOTOR NCR 1249 10 CFR 50.55(e).
SECOND REVISED FINAL REPORT Description of Deficiency Excessive vibrations have been observed in essential raw cooling water (ERCW) pump / motor assemblies for. unit 1 pumps 1A-1 A.and 1 A-2A while running. TVA and Weir Pumps Limited have agreed that the vibration experienced on the ERCW pumps was because of resonant amplification caused by the operating speed being too close to the natural frequency of the pumps.
The fundamental cause of the problem was-that pump design resulted in natural frequencies too near the running speed. A contributing factor also appeared to be the fact that the floor under the pumps was reworked.
Safety Implications Excessive vibrations could lead to failure of the pump and/or motor resulting in failure of the pump to perform its intended ; function of providing raw cooling water to the plant..This would result in loss of the cooling to safety-related equipment and would have affected adversely the safety of operations of the plant.
Corrective Action The solution to the vibration problem proposed by the. pump vendor consists l
of shifting the natural frequency away from the running speed by adding mass to the motors. TVA has evaluated the solution proposed by Weir and-determined it to be effective.
l The permanent addition of weight to the, motors has been seismically l
requalified.- The seismic qualification of the ERCW pumps was verified by a Weir Pumps Report (Report No. TECH /LPD/NV/737/81, Revision 0, dated May i
l 1981). This report was based on the original analyses performed by Mcdonald Engineering and presently included as an addendum to it.
The report concludes that 2500 pounds of additional weight could be added
.to the pumps without altering their seismic qualification. 'TVA has added approximately 1700 pcunds to the 1 A-1 A pump and approximately 2100 pounds to the 1A-2A pump. The vibration levels for each motor are now less than three millimeters (measured from peak displacement).- This is within acceptable limits. Modifications, if required, to other JRCW pumps will be considered separately when they become operational.
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