ML20003G468
| ML20003G468 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/23/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, SQRD-50-328-81, NUDOCS 8104290548 | |
| Download: ML20003G468 (4) | |
Text
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400 Chestnut Street Tower II
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April 23, 1981 1
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SQRD-50-328/81-10 ISOW L
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Mr. Janes R. O'Reilly, Director p
Office of Intepection and Enforcement 4_
U.S. Nuclear gulatory Commission
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Region II - Su e 3100 101 Marietta Str t Atlanta, Georgia '0303
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - CORROSION OF CAR 30N STEEL PIPING -
SQRD-50-328/81 SECOND INERIM P2 PORT The subject deficiency was initially reported to NRC-0IE Inspector F. S. Cantrell on December 30, 1980, in accordance with 10 CFR 50.55(e) as NCR SQN NEB 8035. This uns folicwed by our first interim report dated January 29, 1981. Enclosed is our second interim Mport. We expect to submit our next report by June 9, 1981. This NCR has also been reported for Watts Bar and Bellefonts Nucicar Plants.
If you have any questions concerning this matter, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager l
Nuclear Regulation and Safety i
j Enclosure cc:
Mr. Victor Stello, Jr., Director (Enclosure)F Office of Inspecticas and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 OYsb P00RBRIGllMI.
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A27 810424 013 400 Chestnut Street Tower II April 23, 1981 SQRD-50-328/81-10 Mr. James P. O'Reilly, Director Office of Inspectica and Enforcement i
U.S. Nuclear Regulatory Commission j
Region II - Suite 3100 l
101 Marietta Street Atlanta, Georgia 30303
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - CDRROSION (F CARBCN STEEL PIPING -
SQRD-50-328/81 SECOND INTERIM REPORT t
i The subject deficiency was initially reported to NRC-0IE Inspector F. S. Cantrell on December 30, 1980, in accordance with 10 CFR 50.55(e) as NCR SQN NEB 8035. This was followed by our first interim report dated January 29, 1981. Enclosed is our second interia report. We expect to I
submit our next m port by June 9, 1981. This NCR has also been mported I
for Watts Bar and Bellefonte Nuclear Plants.
If you have any questions concerning this matter, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, i
TE181ESSEE VALLEY AITTHORITY l
L. M. Mills, Manager
,(
Nuclear Regulation and Safety y.
S DLL:DLT:ATK l
Enclosure l
cc:
Mr. Victor Stello, Jr., Dimeter (Enclosure) l Office of Inspectia: and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 cc (Enclosure):
l ARMS, 640 CST 2-C A. W. Crevasse, 401 UBB-C H. N. Culver, 249A HBB-K H. J. Green, 1750 CST 2-C g
Resident Inspector, Sequoyah-NRC l
H. S. Sanger, Jr., E11B33 C-K G. G. Stack, Sequoyah F. A. Szczepanski, 417 UBB-C COORDINATED: EN DES /Bianoc, NUC PR/Maehr
ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2 CORROSION OF CARBON STEEL PIPING SQRD-50-328/81-10 10CFR50.55(e)
SECOND IfEERIM REPORT Description of Condition It has been found that the original criteria for the use of carbon.
l steel piping in raw water systems at TVA nuclear plants may not be l
adequate. Corrosion has been found to cause greater than predicted l
pressure drops when pipes are sized according to standard industry practice. In addition, the corrosion can cease a thinning of the pipe wall which may not have been accounted for in the design of the systems. This condition could affect all raw water systems with carbon steel piping, such as the ERCW System, High Pressure Fire Protection System, and the pump room and oil coolers for the centrifugal charging pumps, the safety injection pumps, and the containment spray pumps. Alsd, most electrical board and room air-conditioning units use carbon steel piping.
The problem of corrosion has been the subject of considerable study at TVA. A brief history of TVA's investigation of this matter was included in our first interim report.
Nonconformance report 2849 reported that the 1/2-inch prelube lines to the ERCW pump bearings and the 1/2-inch cooling water lines for the ERCW pump motor thrust bearing coolers at Watts Bar Nuclear Plant were f.ound to be severely corroded. These lines were later cut up and nowhere was corrosion i
found to completely block the pipe. It has not been determined whether these 1/2-inch lines were capable of passing the design flow. However, l
they should have been changed to stainless steel as previously reco= mended. The recommended changes for Sequoyah were identified in a memorandum dated January 4, 1978. That memorandum contained a statement that the same changes should also be made at Watts Bar. The Sequoyah ERCW pumps did not require bearing prelube and the motor thrust bearing cooler line was already stainless steel. This subtle difference between the two plants was not recognized and, thus, the 1/2-inch lines at Watts Bar were overlooked.
Interim Progress As noted in the first interim report, TVA undertook a comprehensive study of corrosion in carbon steel piping in raw water systems, ultimately defining new, more conservative criteria for design of such piping. TVA is l
continuing its evaluation of Sequoyah Nuclear Plant's (SQN's) raw water l
systems using this criteria to identify any system which does not maintain j
safety capability during the life of the plant. Potential problem areas I
will be identified and corrective actions proposed, i
l i
In the interim, TVA does not consider unit 2 fuel loading contingent on this evaluation. The successful completion of preoperational tests on the safety-related raw water systems will verify the open ability of these systercs in their current condition. In addition, a surveillance test program is being investigated on the safety-related raw water systems to confirm that the safety capability is maintained -during operation.
It should be noted that the first unit 2 ERCW system preoperational test revesled several flow deficiencies, as indicated in Test Deficiency Report PT-631 and nonconformance report SQN SWP 8107. TVA believes these deficiencies were caused in part by improper simulation of reservoir level following loss of downstream dam. Additional testing is planned to further investigate the present capabilities.
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