ML20041D700
| ML20041D700 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/17/1982 |
| 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, NUDOCS 8203080623 | |
| Download: ML20041D700 (2) | |
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TENNESSEE VALLEY AUTHORITY;cc prg i' CH ATTANOOGA. TENNESSEE 374ol 400 Chestnut Street Tower II 00
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February 17, l'932 SQRD-50-328/81-30 m
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Mr. James P. O'Reilly, Director
, h' R E C EIV E D Office of Inspection and Enforcement
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U.S. Nuclear Regulatory Commission MllR 051982> 31 Region II - Suite 3100 Ea k $ { d 101 Marietta Street Atlanta, Georgia 30303 1
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Dear Mr. O'Reilly:
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SEQUOYAH NUCLEAR PLANT UNIT 2 - FOAM SEALS IN MECHANICAL PIPE SLEEVES -
SQRD-50-328/81 FIFTH INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector R. V. Crlenjak on April 16, 1981 in accordance with 10 CFR 50.55(e) as NCR CEB 8108. Interim reports were submitted on April 23, June 30, September 18, and November 18, 1981. Enclosed is our fifth interim report. We expect to submit our next report by April 2, 1982.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY s
h L. M. Mill, Manager a
Nuclear Reg lation and fety Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 l
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9 ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2 FOAM SEALS IN MECHANICAL PIPE SLEEVES SQRD-50-328/81-30 10 CFR 50.55(e)
FIFTH INTERIM REPORT Description of Deficiency Some wall penetration piping sleeves shown on TVA drawing series 47W470 and 47W471 have safety-related piping routed through them. Silicone sealants are provided between the pipe and sleeve at certain locations as shown on TVA drawing series 47W472. These seals have not been cor.3idered in piping analyses for most cases and thereby could result in increases in pipe stresses and support loads for some situations. The maximum pipe movements at the sleeves may also cause failure of the sealant to perform its intended design function as a pressure, water, radiation, and/or fire protection seal.
Interim Progress TVA has conducted tests which show that the silicone foam is flexible in tension, compression, and shear. Initial test results and vendor physical data indicated the silicone foam will not tear or rupture for anticipated pipe movements.
In cases where the pipe is not centered, the movement of the pipe could tear the seal locally; however, a complete loss of a seal through a penetration is not likely. Tests recently completed indicate some loss of sealing where large displacements occur.
TVA is currently evaluating the effects of the silicone foam seals on the pipe and on the seal itself. Pipe movement data has been compiled for the evaluation.
Data from initial tests conducted by TVA on silicone foam seal indicated spring rates for the foam seal in tension, compression, and shear. It has been determined that these initial spring rates, determined from tests of a single pipe size, may not be realistic when applied to other pipe / sleeve sizes. Therefore, in order to obtain ~ realistic spring rates, TVA has performed an extensive test of the silicone foam seals involving a range of pipe / sleeve sizes. Techniques for modeling the foam have been developed.
Six points for piping that penetrates the shield building at critical elevations where large pipe movements could be expected were selected for analysis. Analysis of two of the six points has been performed with new spring rates from the test program. TVA has rescheduled review of analysis results on all six points and anticips.tes submittal of a final report by April 2, 1982.
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