05000361/LER-1982-019, Forwards LER 82-019/03L-0.Detailed Event Analysis Submitted

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Forwards LER 82-019/03L-0.Detailed Event Analysis Submitted
ML20055A630
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 07/01/1982
From: Ray H
SOUTHERN CALIFORNIA EDISON CO.
To: Engelken R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20055A631 List:
References
NUDOCS 8207190265
Download: ML20055A630 (2)


LER-2082-019, Forwards LER 82-019/03L-0.Detailed Event Analysis Submitted
Event date:
Report date:
3612082019R00 - NRC Website

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'f,fE0 Southern California Edison Company s AN ONOFRE NUCLE AR GENER ATING ST A TION NJ m h6 !I p.o.soxtaa S A N C LEMENT E. C A LIFORNI A 92672 - . jf H. B. R AY T E ( E Pe40 N E

. tar'oawaaaata July 1, 1982 m mam U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 92596-4368 Attention: Mr. R. H. EngelKen, Regional Administrator

Dear Sir:

Subject:

Docket No. 50-361 Licensee Event Report No.82-019 San Onofre Nuclear Generating Station Unit 2

Reference:

Letter, H.B. Ray (SCE) to R.H. Engelken (NRC),

dated May 24, 1982 (LER 82-012)

This letter provides the report pursuant to Technical Specification 6.9.1.13.b, of an event involving Limiting Condition for Operation (LCO) 3.7.5 on the Control Room Emergency Air Cleanup System (EACS).

On Apri1 24, 1982, Train "B" of the Control Room EACS was declared inoperable. The inline heater (E296) was cycling on and off for no apparent reason. LER 82-012, referenced above, was issued discussing this occurrence, including the installation of Jumpers across the flow.

control switch in order to permit the removal of moisture from activated charcoal by operation of the system for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with heaters on.

The defective flow control switch was later replaced, pitot tube reoriented and flow switch recalibrated in both Trains "A" and "B" as corrective action resulting from our investigation of that event.

Operability of the Control Room EAS was subsequently demonstrated by periodic surveillance in accordance with the requirements of Technical Specification 4.7.5.b, on 5/7/82 for Train "A" and on 5/21/82 for Train "B". On 6/3/82, however, the same surveillance test revealed that the heater on Train "A" was again cycling on and of f. Train "B" was shown to also exhibit a heater cycling problem and both Trains "A" and "B" were again made operable by installation of Jumpers across the flow control switch in each train. This LER (No.82-019) is a result of this second oCCurence.

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8207190265 920701 PDR ADOCK 05000361 S PDR N

< 1 Mr. R. H. Engelken July 1, 1982 Our research has determined that the flow control switch is installed by ihe heater vendor to satisfy an Underwriter's Laboratory requiren:ent for protection of the heater. Actuation of the switch results from the pressure sensed by a pitot tube in the air flow path. Vendor contacts indicate the switch is reliable, and the problem is most probably due to improper installation or erroneous specification of switch actuating range.

Proper installation was verified and an evaluation of switch selection and possible permanent modification is ongoing. The temporary mod-ification of installing jumpers across the. flow switch will remain in effect to maintain the Control Room EACS operable until permanent design changes are completed. Disabling this switcl. does not remove protection against heater overheating, as a high temperature cutout will protect the heater if the thermostat control fails.

A completed LER form summarizing this event is enclosed. If there are any questions regarding the above, please contact me.

Sincerely,

/ c

Enclosure:

LER No.82-019 cc: A. E. Chaffee (USNRC Resident inspector, San Onofre Unit 2)

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

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