05000361/LER-1982-012, Forwards LER 82-012/03L-0.Detailed Event Analysis Submitted

Forwards LER 82-012/03L-0.Detailed Event Analysis Submitted

ML20053B957
Person / Time
Site:	San Onofre
Issue date:	05/24/1982
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20053B958	List: 05000361/LER-1982-012, Forwards LER 82-012/03L-0.Detailed Event Analysis Submitted 05000361/LER-1982-012-03, /03L-0:on 820424,heater in Train B of Control Room Emergency Air Cleanup Sys Cycled on & Off.Caused by Erratic Functioning of Flow Control Switch & Pitot Tube. Switch Replaced & Pitot Tube Reoriented
References
NUDOCS 8206010375
Download: ML20053B957 (2)

LER-1982-012, Forwards LER 82-012/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
3611982012R00 - NRC Website

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S AN C LEME NTE, C ALIF ORNI A 92672 H. R. R A Y reterwoNe May 24, 1982 ira tion u AN Aos a m m "a U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368 Attention: Mr. R. H. Engelken Regional Administrator

Dear Sir:

Subject: Docket No. 50-361 Licensee Event Report No.82-012 San Onofre Nuclear Generating Station, Unit 2 This letter describes a reportable occurrence involving the Control Room Emergency Air Cleanup System, Train "B".

This submittal is in accordance with the reporting requirements stipulated in Section 6.9.1.13.b of Appendix A to the Facility Operating License NPF-10.

Technical Specification 4.7.5.b requires that each Control Room Emergency Air Cleanup System be demonstrated operable at least once every 31 days by running the system at least 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with the heaters on.

On April 24, 1982, during the monthly surveillance test of the Control Room Emergency Air Cleanup System, the heater of Train "B" cycled errat-ically between the on and off positions. This constitutes an unacceptable operating status in that the heater which is required to prevent moisture degradation of the charcoal bed filter cannot maintain the relative humidity in the air stream. The cause was traced to flow control switch FCL-9753-2 and the associated pitot tube.

The function of this switch is to shut off the heater current at low air flow to prevent the heater from burning out. Low air flow is sensed by a pitot tube and the resulting signal is transmitted to the flow switch.

The action statement associated with this Limiting Condition for Operation (Technical Specification 3.7.5) requires that an inoperable system be restored to operable status within seven days.

Operability of the system was re-established within the prescribed seven days by installing a jumper across the flow switch and successfully completing a full 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> surveillance test on April 26, 1982. Subsequent actions have included replacement of the flow switch, reorientation of the pitot tube, and recalibration of the system.

U[3 9,}1 8206010

Mr. R. H. Engelken May 24, 1.982 o

This incident had no effect on public health or safety.

Should you require additional information concerning this incident, please contact me.

Sincerely, I

6 Enclosure cc:

U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Office of Management Information and Program Control Institute of Nuclear Power Operations (INPO)

A.E. Chaffee (USNRC Resident Inspector, San Onofre, Unit 2)