ML20055H263

Discusses Model 3RE-7870 Not Being Declared Operable Due to Lack of Process Flow.Monitor Failed on 900708.Caused by Moisture Intrusion Into Housing.All Affected Components Repaired or Replaced

ML20055H263
Person / Time
Site:	San Onofre
Issue date:	07/23/1990
From:	Nandy F SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9007250388
Download: ML20055H263 (2)

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Southem Califomia Edison Company 23 PARKER STREET

'. IRVINE CAUFoRNIA 927 80 F.R.NANoY TELEPHONE o cz,..oe. , ,,veu.. uce ei~o July 23, 1990 m.i eere.=

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U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555

Subject:

Docket No. 50-362 Special Report San Onofre Nuclear Generating Station, Unit 3 This report is being submitted in accordance with Technical Specification (TS) 3.3.3.1, Table 3.3 6, Action 19, of Facility Operating License NpF 15, San Onofre Unit 3. The TS requires Southem '  ;

California Edison (SCE) to submit a Special Report when Condenser Evacuation System Noble Gas

- Activity Monitor 3RE 7870 becomes inoperable for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> during Modes 1,2, and 3 for v the wide range channel, and during Mode 4 for the normal range channel. i On July 7,1990, at 0745, Unit 3 entered Mode 4 from the Cycle 5 refueling outage. At that time, TS 3.3.3.1, Action 19, was entered because 3RE-7870 had not been declared operable, due to the lack of i process flow, following satisfactory completion of the quarterly channel functional test (CFT) requhed by TS 4.3.3.1, Table 4.3 3 (the monitor is TS 3.0.4 exempted). ,

On July 8,1990, with the unit in Mode 4, the operations surveillance performed for retuming 3RE-7870 to operable status found the monitor failed. While troubleshooting efforts were in progress, the unit proceeded to Mode 3 on July 14,1990. ,

Troubleshooting results determined that moisture intruded into the monitor housing, due to 3E 7870 [

being out of service for a period of time following completion of the CFT. Moisture originating from E air ejector discharge stack accumulated in the monitor discharge line and reached the monitor detector.

Moisture intrusion was prevented on the suction side of the monitor by the sample pump filters.  ;

The monitor discharge line was drained and all affected components were either repaired or replaced.

Appropriate plant startup procedures will be modified to specifically address reviewing return to senice requirements for radiation monitors prior to changing operational modes.

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9007250388 900723 PDR ADOCK 0500036:2 S PDC fDel p

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Document Control Desk 2- July 23, 1990 t-Y.

Following completion of satisfactory CFT and operability testing,3RE 7870 was returned to service on July 18,1990.- If you require any additional information, please let me know.

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Very truly yours,

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cc: J. B. Martin (Regional Administrator, USNRC Region V)

C. W. Caldwell (USNRC Senior Resident inspector, Units 1,2, and 3)  ;

J. R. Tatum (NRR SONGS Project manager)

Institute of Nuclear Power Operations ONPO) '

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