ML20127A615

Special Rept:On 921211,meteorological Monitoring Delta Temp Instrument Declared Inoperable When Difference Between Primary & Secondary Sensors Noted to Be Excessive.Corrective Actions Did Not Resolve Problem.Sensors Replaced

ML20127A615
Person / Time
Site:	San Onofre
Issue date:	12/24/1992
From:	Rosenblum R SOUTHERN CALIFORNIA EDISON CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
NUDOCS 9301120022
Download: ML20127A615 (1)

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E714) 454 4506 NGC6 F AH F4E Clut Att.pnv AF# AFFM Mr. John B. Martin, Administrator U. S. Nuclear Regulatory Commission, Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368

Subject:

Docket No. 50-361 Special Report San Onofre Nuclear Generating Station, Unit 2 This report is being submitted in accordance with Technical Specification (TS) 3.3.3.4, " Meteorological Instrumentation," Action 'a' of Facility Operating License NPF-10, San Onofre Unit 2. The TS requires Southern California Edison (SCE) to submit a special report when the meteorological monitoring instrumentation becomes inoperable for more than 7 days.

Two channels (primary and secondary) provide delta temperature monitoring.

Each channel is provided with two temperature sensors, one sensor at the 10 -

meter elevation and the other at the 40 meter elevation. These sensors provide input to a computer for delta temperature readings.

On December 11, 1992, the meteorological monitoring delta temperature instrument was declared inoperable when it was noted that the difference between the primary and secondary sensors was excessive. Initial troubleshooting indicated the problem to be associated with cable connectors for the 10 meter secondary delta temperature sensor. However, corrective maintenance on the cable connectors did not resolve the problem. Both the primary and secondary delta temperature sensors were subsequently replaced, and the delta temperature instrument was returned to service on December 24, 1992.

If you require any additional information, please let me know.

Sincerely, i

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M B.Nuclear Regulatory Fields, NRC Project Commission Manager, SanDocument Control Onofre Units 2 andDesk 3

C. W. Caldwell, NRC Senior Resident inspector, San Onofre Units 1, 2 & 3 110087 - y1 9301120022 921224 PDR ADOCK 05000361 /lhu

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