ML20080Q280

Forwards Updated LERs 83-105/03X-1 & 83-076/03X-1

ML20080Q280
Person / Time
Site:	San Onofre
Issue date:	09/28/1983
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20080Q282	List: ML20080Q280
References
NUDOCS 8310120342
Download: ML20080Q280 (2)

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S AN C L EMENT E. C ALIFORNI A 92674 'dhe H. B. R A Y ' t'u n asoN t SunoN AN Aae= September 28, 1983 o n o.2 , ..

U.S. Nuclear Regulatory Commission office of Inspection and Enforcerent Region V 1450 Maria Lane, suite 210 Walnut Creek, California 94596-5368 3

Attention: Mr. J. B. "artin, Regional Administrator

Subject:

Docket Noc. 50-361 and 50-362 Licensee Event Report Nos.83-076, Rev. 1 and 83-105, Rev. 1 San Onofre Nuclear Generating Station, Unite 2 and 3

Reference:

a) Letter, H. B. Ray (SCE) to J. B. Martin (URC),

dated August 2, 1983 b) Letter, H. B. Rai (SCE) to J. B. Martin (NF2),

dated August 31, 1983 he referenced letters provided you with the regtired 30-cay Reports parsuant to Section 6.9.1.13.b of Appendix A, Technical Specifications to Facility Operating Licenses NPF-10 and hFF-15 for w San Onofre Units 2 and 3, respectively, for occurrences involving Limiting Condition for Operaticn (tCO) 3.3.2 associated with the To::ic Gas Isolation System (TGIS) . As indicated in Reference (a),

a revise.f Licensee Event Report (LER) was to be submittad by September 15, 1983, however, additional tine was required to determine the appropriate corrective actions. Enclosed are LER 83-076, Revision 1, and LER 83-105, Revision 1, involving a similar occurrence which include corrective actions to prevent recurrence.

On July 3, 1983, and also on August 1, 1983, the pilot flames of Trains "A" and "B" Toxic Gas Isolation System (TGIS) butane / propane

" nonitors were found extingaished while performing the once-per-shift surveillance. For the July 3, 1963, event, in accordance with LCO 3.3.2, Table 3.3-3, Action Statenent 15, the Ccntrol Poon Emergency Air Cleanup System was manually ' aced in the isolation mode within one hour. Trains "A" and "B" wer e returned to operable status within seven hours. For the Aagust 1, 1983, event, since Train "B" was returned to operable status 9310120342 030928 PDR ADOCK 05000361 S PDR I

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• J. B. Martin September 28, 1983 Within one hour, in accordance with LCO 3.3.2, Action Statement 14, action was initiated to return Train "A" to operable status within

. seven days. Train "A" was returned to operable status within two days.

Investigation into the flameout condition by the operators revealed no apparent cause for these flameouts. Sufficient fuel supply existed and the valve lineup was correct.

For both events, TGIS failed to alarm upon a flameout condition.

These events prompted further investigation into: (a) the cause of the flameouts when sufficient fuel supply exists and, (b) the failure of TGIS to actuate upon a flameout condition.

The cause of the flameouts when sufficient fuel supply exists could not be determined. A design change is being prepared to eliminate the potential of back leakage of nitrogen into the instrument air lines to the TGIS butane / propane monitors. Installation of an enclosure around the pilot flames is under consideration to minimize environmental effects.

The failure of TGIS to actuate upon a flameout condition was due to limitations in utilizing the low alarm setpoint for flameout detection. TGIS utilizes a direct method of flame detection involving a thermister above the pilot flames. Due o fluctuations in the operating level of the monitor, it is difficult to maintain the low alarm setpoint close enough to the operating level without receiving excessive alarms. A design change is being prepared to:

1) add a new flameout detection signal to the TGIS actuation circuitry and, 2) to eliminate back leakage of nitrogen to the burner.

If there are any questions regarding these events, please so advise.

Sincerely, G5[

Enclosures:

LER 83-076, Revision 1 (Unit 2)

LER 83-105, Revision 1 (Unit 2) 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) l r.

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