ML20043B664

Special Rept 90-09:on 900515,condenser Vacuum Exhaust Vent mid-range Noble Gas Monitor 2-RM-90-405 Inoperable for More than 7 Days.Caused by Damaged/Degraded Detector Cable.New Cable Expected to Be Installed by 900608

ML20043B664
Person / Time
Site:	Sequoyah
Issue date:	05/29/1990
From:	Wallace E TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
90-09, 90-9, NUDOCS 9005310081
Download: ML20043B664 (2)

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TENNESSEE VALLEY AUTHORITY  ;

- CHATTANOOG A. TENNESSEE 37401 >

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SN 157B Lookout Place ~

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MAY 291990 U.S.' Nuclear Regulatory C eyission  ;

ATTN: -Document Control % c'.

Hasnington, D.C. 20555

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- Gentlemen:

In,the Matter of ) Docket Nos. 50-328 1 Tennessee Valley Authority ) -t

'2. - ~ SEQUOYAH NUCLEAR PLANT (SQN)'- TECHNICAL SPECIFICATION (TS) 3.3.3.7 - SPECIAL REPORT.90-09 The enclosed special report provides details concerning the Condenser Vacuum Exhaust Vent Mid-Range. Noble Gas Monitor 2-RM-90-405 being inoperable for

-greater than seven days. This report is being submitted in accordance with TS' Action Statement (d) of Limiting Condition-for Operation 3.3.3.7. <

If you have any questions concerning this submittal, please telephone M, A.' Cooper at (615) 843-6651.

Very truly yours, ,

TENNESSEE. VALLEY AUTHORITY

)- n E. G. Hollace, M n&ger Nuclear' Licensing and Regulatory Affairs-  ;

Enclosure. )

cc-(Enclosure):

' Ms. S. C' Black, Assistant Director-for Projects TVA Projects Division 4

. U.S.: Nuclear. Regulatory Commtssion 1

' One White Flint, North 11555 Rockville-Pike Rockville, Maryland 20852 NRC Resident Inspector j Sequoyah Nuclear Plant 2600 Igou Ferry Road

. Soddy Daisy, Tennessee 37379 -

Mr. B.' A. Wilson, Assistant Director for Inspection. Programs '

TVA Projects Division U.S. Nuclear. Regulatory Commission Region II 101-Marietta Street, NH, Suite 2900 Atlanta,: Georgia, 30323 g 9005310081 900529 ,

LPDR ADOCK 05000328

's - PDC An Equal opportunity Employer 4

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< ENCLOSURE

- SQN SPECIAL REPORT 90 This special report is being made in.accordance with Action Statement (d) of-Limiting Condition for Operation (LCO) 3.3.3.7.- The mid-range noble gas- .

' radiation nonitor (RM) (2-RM-90-405) for.the' condenser vacuum exhaust-vent has

-been inoperable for greater than seven days.

On May 15,1990, at -1100 Eastern daylight time, with Unit i shut down. for a refueling outage and Unit 2 in Mode l'(100 percent power, 2,235 pounds per square inch gauge, and 578 degrees Fahrenhe i t), LC0 3.3.3.7 was entered when a trouble alarm on Control Room Panel 2-M-30 was observed. An investigation into the-situation revealed that 2-RM-90-405 had apparently malfunctioned.

Work Request C003224 was initiated to inspect the RM and return it to service. Inspection of the monitor revealed a damaged and degraded detector cable. The cause of the cable being damaged was indeterminate. When maintenance was1 scheduled to replace the cable, it was identified that a replacement' cable was.not available and that it will take approximately 14 days to procure a new cable. Based on this delivery date, the projected-schedule for receipt and installation of the new cable is June 8, 1990.

- Until the RM can be returned to service, an alternate method of monitoring the

. appropriate parameters has been established. The alternate method is accomplished by Operations closely monitoring the-condenser vacuum exhaust Postaccident Monitors'2-RM-90-255 and 2-RM-90-256. 'These~ monitor channels, which have overlapping ranges, monitor effluent radioactivity concentrations by~ detection of' exposure rates in the vicinity of the condenser vacuum pump exhaust duct. These alternate monitors were originally the means of

-monitoring the condenser vacuum exhaust vent before the 2-RM-90-405 monitor was installed.

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