ML20024E472

LER 83-076/03L-0:on 830703,during Mode 5,pilot Flames of Trains a & B Toxic Gas Isolation Sys Butane/Propane Monitors Found Extinguished.Caused by Low Alarm Setpoint.Low Alarm Setpoints raised.W/830802 Ltr

ML20024E472
Person / Time
Site:	San Onofre
Issue date:	08/02/1983
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
1309U, LER-83-076-03L, LER-83-76-3L, NUDOCS 8308150096
Download: ML20024E472 (4)

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES O10 o 2 l On July 3,1983, at 0958, with Unity 2 and 3 in Mode 5, the pilot flames of l 1o 1211 Trains "A" and "B" Toxic Gas Isolation System (TGIS) butane / propane monitors l o 4 l were found extinguished while performing the once-per-shif t surveillance. In j l 15 I Lac _cordanc.e_with LCO 3.3.2, Table 3.3-3, Action Statement 15, the Control Room l Io le l l Emergency Air Cleanup System was manually placed in the isolation mode of l o l 7 l l operation within one hour. Public health and safety were not affected by this  ;

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l 5 lo ll Investigation revealed no apparent reason for the pilot flameouts. The failure l l t li ll of TGIS to actuate upon the flameout was apparently due to a low alarm setpoint l 1 2 l on both butane / propane monitors. No cause for the low alarm setpoint has been l

[il3ll determined. The low alarm setpoints were raised and TGIS Trains "A" and "B"  ;

i 4 l were returned to operable status on July 3,1983,at 1635 (See Attachment.)  ;

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<r-i ATTACHMENT TO LER 83-076 SOUTHERN CALIFORNIA EDISON COMPANY SAN ONOFRE NUCLEAR GENERATING STATION UNIT NO. 2, DOCKET NO. 50-361 SUPPLEMENTAL INFORMATION FOR CAUSE DESCRIPTION AND CORRECTIVE ACTIONS The investigation into the flameout of both channels of TGIS when sufficient fuel supply exists is continuing. The possibility of nitrogen entering the instrument air line to the butane / propane monitors is being examined.  ;

The method of flameout detection and subsequent TGIS initiation is being reviewed.- TGIS utilizes the low alarm setpoint to detect a flameout condition. However, the low alarm setpoint is near the operating level of the monitor and excessive spurious alarms occur.

A revised LER ill be submitted by September 16, 1983.

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a ES GVED EC Southern California Edison Company Wf=

S AN ONOFRE NUCLE AR GENER A TING ST A TION si f

P .O. B O K 128 S A N C L EMEN T E. C A LIFORNI A 92672 H.B RAY **  ! $.y TELEPHONE u m ,oN +.a Naan.

August 2, 1983 " ' ' ' " * " "

U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368 Attention: Mr. J. B. Martin, Regional Administrator

Subject:

Docket Nos. 50-361 and 50-362 30-Day Report Licensee Event Report No.83-076 (Docket No. 50-361)

San Onofre Nuclear Generating Station, Units 2 and 3 Pursuant to Section 6.9.1.13.b of Appendix A, Technical Specifications to Facility Operating Licenses NPF-10 and NPF-15 for San Onofre Units 2 and 3, respectively, this submittal provides the required 30-day written report and a copy of Licensee Event Report (LER)83-076 addressing an occurrence involving Limiting Condition for Operation (LCO) 3.3.2 associated with the Toxic Gas Isolation System (TGIS). Since this occurrence involves a shared system between Units 2 and 3, a single LER for Unit 2 (Docket 50-361) is enclosed in accordance with NUREG 0161. As indicated in the enclosed LER, our investigations into this incident are continuing and a revised LER, based upon the results of this investigation, will be submitted by September 16, 1983.

If there are any questions regarding this event, please so advise.

( Sincerely, l

H6h 7 /rw4

Enclosure:

LER 83-076 9

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Mr . J. B. !{artin August 2, 1983 cc: A.E. Chaffee (USNRC Resident Inspector, Units 2 and 3)

J.P. Stewart (USNRC Resident Inspector, Units 2 and 3)

U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Division of Technical Information and Document Control Institute of Nuclear Power Operations (INPO)

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