ML20003D568
| ML20003D568 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/18/1981 |
| 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 8103270672 | |
| Download: ML20003D568 (3) | |
Text
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i TI.Y, r M c E V A LLEY A L ~ '-
400 Chestnut Street Tower II March 18, 1981 SQRD-50-328/81-18 Mr. James P.
'Reilly, Director Office of Insp tion and Enforcement U.S. Nuclear Re atory Ccmaissico Regica II - Suite 100 101 Marietta Street Atlanta, Georgia 30,
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - ENVIRONMENTAL QUALIFICATION CF VALVE LI. T U
SWITCHES - SQRD-50-328/81 REVISED FINAL REPORT The subject deficiency as initially reported to NRC-OIE Inspector R. W. Wright en February 2, 1981, in accordance with 10 CFR 50.55(e) as NCR's EEB 8102, 8104, and 8105. A final report as submitted on March 4, 1981. Enclosed is our revised final report. The report has been revised in order to clarify our earlier response.
If you beve 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 j
oc: Mr. Victor Stallo, Director (Enclosure) y Office of Inspectia: and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 9
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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)
REVISED FINAL REPORT Description of Deficiency Limit switches associated with containment isolation valves in the control air, main steam, and sampling systems have been determined to be not qualified for the calculated accident environment for the area in which they are located. The limit switch manufacturer, model number, and accident environment are noted below.
Manufacturer Model No.
Environment Valve ID Namco EA-700 Temperature:
150 F FCV-32-81 Namco SL3C-B2 Pressure: ATM FCV-32-103 Relative Humidi.yy (RH) 100% FCV-32-111 Radiation: 7X10 Rads Chemical Spray: No Namco SL3C-B2 Temperature: 297 F FCV-1-149 2
Pressure: 22.9 lb/in FCV-1-148 RH:
100%
FCV-1-147 Radiation: NA FCV-1-150 Chemical Spray: No FCV-1-14 FVC-1-32 FCV-1-25 FCV-1-7 Microswitch P/N-LSC4C Temperature: 327 F FCV-43-2 2
Pressure: 26.4 lb/in FCV-43-11 RH:
100%
FCV-43-22 g
Radiation:
1.2X10 Rads FCV-43-34 Chemical Spray: Yes FCV-43 FCV-43-201 FCV-43-202 FCV-43-207 FCV-43-208 Safety Implications Since adequate environmental qualification cannot be confirmed, the limit switches must be t sumed to fail in an adverse manner. This
" worst-case" condition e.sid result in a spurious signal from the open limit switch that causes valves FCV-32-81, -103,. -111, and FCV-1-149, -148,
-147, -150, -14, -32,
-7, and -25 to change position (open) when the containment isolation switch is reset. A local containment isolation reset switch has been added for valves FCV-43-2, -11, -22, -34, and -75 such that they remain. closed-when the containment isolation relays associated with 9
' O the solid state protection system (SSPS) are reset even if the open limit switches have failed. Failure of the limit switches for valves FCV-43-201,
-202, -207, and -208 could result in a false indication of the valve position only. This potential for false indication of valve position applies to all of the valve limit switches identified above.
Without proper assurance of limit switch conditien, any inadvertent actuation of the control switches for these valves could possibly result in loss of the containment isolation boundary.
Corrective Action Before June 30, 1982, the unqualified limit switches will be replaced per the guidelines of NUREG-0588 with switches that are environmentally qualified for the calculated accident environment. In the interim TVA has established administrative controls that require the handswitches of these valves to either be placed in the proper position such that the valve will be unable to change position in the event of limit switch failure or have control power removed before manual reset of the containment isolation relays. These controls are being utilized at Sequoyah unit 1.
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