ML19352A139
| ML19352A139 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/04/1981 |
| 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, 10CFRR-50.55E, SQRD-50-328-81, NUDOCS 8103110433 | |
| Download: ML19352A139 (2) | |
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400 Chestnut Street Tower II March 4, 1981
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?$Q%e Mr. Jages P.
'Reilly, Director.
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Office of Insp' tion and Enforcement c-U.S. Nuclear Re atory Commissim
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Region II - Suite 100 101 Marietta Street Atlanta, Georgia 30., 3
Dear Mr. C'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - ENVIRONMENTAL QUALIFICATION OF VALVE LLMIT SWITCHES - 3QRD-50-328/81 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector R. W. Wright m February 2, 1981, in accordance with 10 CFR 50.55(e) as NCR's EES 8102, 8104, and 8105. Enclosed is our final mport.
If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Enclosure cc:
Mr. Victor Stello, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 (bo\\f 61 1
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ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2 ENVIRONMENTAL QUALIFICATION OF VALVE LIMIT SWITCHES SQRD-50-328/81-18 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency Limit switches associated with containment isolation valves in the control air, main steam, and sampling systems have been deter =ined to not be qualified for the calculated accident environment for the area in which they are located. The limit switch manufacturer, model number, and accident environ =ent are ncted below:
Manu facturer Model No..
Environment Namco EA-TOO Temperature:
150 F Namco SL3C-32 Pressure: ATM Relative Humidiyy (RH) 100%
Radiation: 7X10 Rads Chemical Spray: No Namco SL3C-B2 Te=perature: 297 F 2 Pressure: 22.9 lb/in RH:
1005 Radiation: NA
' Chemical-Spray: No Microswitch P/N-L5C4C Te perature: 327 F 2 Pressure: 26.4 lb/in RH:
100%
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' Radiation:
1.2X10 Rads Chemical Spray:
Yes Safety Implications Since adequate environment qualification cannot be confirmed, it must be assumed that the limit switches fail in an adverse manner. This
" worst-case" condition could : result in a spurious signal from the limit switch that causes a containment isolation valve to change position.- - This inadvertent action could possibly result in loss of the containment isolation boundary.
Corrective Action
- The unqualified _ limit switches will 'be replaced with limit switches that1are enviren=entally qualified for: the calculated accident environment. ~ A TVA engineering change notice (ECN) will be issued
'which specifies an implementation requirement for. this work to be accomplished before unit 2. fuel loading. This change will be implemented in accordance with 'thes'e schedu?i require =ents.
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