RBG-37145, Special Rept:On 920622,meteorological Tower Aspirator Fault Light Found Lit During Routine Surveillance.Caused by Roosting Bird.Addl Repairs to 30 Foot Flow Switch Ongoing & Util Is Investigating Methods to Remove Roosting Bird

Special Rept:On 920622,meteorological Tower Aspirator Fault Light Found Lit During Routine Surveillance.Caused by Roosting Bird.Addl Repairs to 30 Foot Flow Switch Ongoing & Util Is Investigating Methods to Remove Roosting Bird

ML20101Q273
Person / Time
Site:	River Bend
Issue date:	07/10/1992
From:	Odell W GULF STATES UTILITIES CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RBG-37145, NUDOCS 9207140221
Download: ML20101Q273 (3)

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EnftR BE %D $f 4*ON ' Post Wtri 80* 220 : St. TRANCISVLil LOutStANA 70776 ARI A (Opt 504 - 635 00fe4 N6eMI July 10,1992 RBG 37145 ,

File Nos. G9.5, G9.25.1.3'

-U.S. Nuclear Regulatory Commission

- Document Control Desk Washington, D.C. 20555 Gentlemen:

River Bend Station - Unit 1

_ Docket No. 50-458 Enclosed is' Gulf States Utilities Company's Special Report concerning inoperative meteorological instruments at River Bend Station (RBS). This repon .a submitted' pursuant to RBS Technical Specification 3.3.7.3 and 6.9,2.

Sincerely

.W.H. Odell Manager - Oversight ' q River Bend Nuclear Group LAE/PDG/JPS/DCH/DLR/kYm cc:  ; U.S._ . Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 -

. Arlington, TX-76011

- NRC Resident Inspector m .P.O. Box 1051-o$$ - St. Fmncisvilli,'.LA 70775

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@n INPO Records Cente.

PO 1100 Circle Parkway -

.pg Atlanta, GA 30339.-3064..

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CQ g< Mr. C. R. Olmrg.

m N Publi_c Utility Commissioner of Texas . -

OE - 7800 Shoal Creek Blvd., Suite 400 North - -

g/,k i 140i13 Austin, TX 78757 -

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.REPORTJS CONDITION On June 22,1992 with the reactor shut down for a refueling outage (Operational Cordition 5),

the meteorological tower aspiratcr fault light was found lit during routine surveillance.

Maintenance work order request (MWOR) R160607 was initiated to troubleshoot and repair and LCO 92-320 was mcorded to track completion. On 6/27/92 condition report 92-0522 was initiated to insure tha( a Special Report- would be completed pursuant to the Technical Specification 3.3.7.3 requirement of 10 days.

INVESTJGATION l The meteorological tower at River Bend Station is a 150 foot open tatticed tower located 2800 <

feet west of the reactor. Meteorological instrumentation is located at two levels 30 foot and 150 foot and was supplied by Teledyne-Geotech.

1 Iocated on the tower is instrumentation for measuring air temperatum at both 30 foot and 150 foot elevations. The air temperature RTDs are shielded from the sun and continuously washed by ambient temperature air by a motor aspirated thermal radiation shield (MATItS). The MATRS uses a switch to indicate flow. This switch controls the illumination of the aspirator fault light.

. This continuous wash of air is required to distinguish the very small delta temperature l diffeicaces between the 150 foot and the 30 foot booms needed to determine air stability classes. The stability classes are used in the event of an accident to calculate offsite doses and determine protective rtion recommendations such as sheltering or evacuating the public. The ruaguitude of these delta temperatures between stability classes is approximately 0.3 degrees F.

' i On !uly 7,1992, the condition of the meteorological tower was investigated under MWOR.

R160607. ' A large bird was observed to te roosting on the 150 foot boom. The instrument booms were lowered and the aspirator screens examined. Both the 150 foot and the :0 foot aspirator screens were found clogged with dirt. When the 150 foot aspirator screen was cleaned, the fault light extinguished. Since the 30 foot screen also showed dirt accumulation but no fault

light il!uminnted, the now switch was removed and examined. The flow switch in the 30 foot aspirator was found to be failed.

In addition, the 150 foot secondary wind direction vane was found to be; severely bent with numerous small holes and nicks. Similar nicks and holes wem found in the 150 foot primary  ;

wind direction vane. Coy,arate security examined the weather instntments and detennined that the damage was not caused by firearms. At present, neither of the 150 foot wind direction l instruments are operabic.

i Examination of the 30 foot boom showed evidence of mud and fresh blood. Substantial amounis.

of what appeared to be patches of fur littered the base of the meteotulogical tower The cause of failure appear.; to be caused by tue roosting bird.

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.CO'RIECTIVE ACTION Additional repairs to the 30 foot flow switch and repair and troubleshoothg of the 150 foot wind.

direction instniments are ongoing. GSU is investigating methods to remove the roosting bird.

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