ML20062G364

Special Rept:On 901108,reactor Bldg Ventilation Accident Range Radiation Monitor Inoperable for More than Seven Days. Caused by Component Failure.Reactor Bldg Accident Range Radiation Monitor Declared Inoperable

ML20062G364
Person / Time
Site:	Hatch
Issue date:	11/16/1990
From:	Hairston W GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-1370, NUDOCS 9011290142
Download: ML20062G364 (4)

Text

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{ Georga Powet Cut parrt

,, ... 333 Peomont A,enue 4 Attarm Goorg a 30308 ,

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.blephonri 404 526 3195

• • Ma. Lng Address 40 invernon Center Panay .

Post Once Box 1295 B>rrninghurt Alabama 3L201 lelephcne 20$ Bf;0 5581 -

' the soahern ek: ant. system W, G. Hairston,111 -

Son-or Vce Presdent Nudear Operabons

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1000932 November 16,.1990- I I

U.S. Nuclear Regul'atory Commission ATTN: Document Control Desk i, l Washington, D.C. 20555- 1 PLANT HATCH - UNIT 2' .

NRC DOCKET 50-366- J l

OPERATING LICENSE NPF-5 .

. SPECIAL REPORT-2-90-004 REACTOR BUILDING VENTILATION' ACCIDENT RA "t S RADIATION MONITOR INOPERABLE FOR LONGER l

THAN SEVEN DAYS RESULTS IN SPECIAL REPORT Gentlemen:

In accordance with the requirer:nts- of the Unit 2 Technical Specifications Table 3.3.6.4-1, 'ncte (b), Georgia .Powerf Company is submitting .the enclosed Special -Report concerning an' event where. the reactor building ventilation accident. range radiation monitor- -was inoperable for longer than seven days'. 'This' event- occurred at Plant Hatch

- Unit 2. 1 Sincerely, y)). $lYW W. G. Hairston, III' JKB/et

Enclosure:

SR 50-366/1990-004 c: (See next paga.)

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L 9011290142 901116 l {DR ADOCK 05000366 l PDC '

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Ge$tyia PowerI l$ j e  :

I -i l- U.S. Nuclear Regulatory Commission November 16, 1990 Page Two .!

c: Georaia Power Company .

Mr. H. L. Sumner, General Manager - Nuclear Plant }

Mr.'J. D. Heidt, Manager Engineering and Licensing . Hatch 9

NORMS H

.I U.S. Nuclear Reaulatory Commission. Washinaton. D.C.  ;

Mr.-K. Jabbour, Licensing Project Manager - Hatch  ;

U.S. Nuclear Reaulatory Commission. Reaion II .i Mr. S. D. Ebneter, Regional Administrator . . .

Mr. L. D.- Wert, Senior Resident Inspector.- Hatch 1

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ENCLOSURE l =

' PLANT HATCH - UNIT 2-l NRC DOCKET 50-366'

-OPERATING LICENSE NPF-5 SPECIAL REPORT 2-90-004-REACTOR BUILDING = VENTILATION ACCIDENT RANGE RADIATION MONITOR INOPERABLE FOR l .I

. LONGER THAN=SEVEN DAYS RESULTS IN SPECIAL REPORT' a

L_ A. REQUIREMENT FOR REPORT This report is required per Unit'2 Technical Specifications Table 3.3.6.4-1 note (b). Item 14 of. that table requires this instrument to remain operable' <

l while the Unit is in operational conditions 1, 2 or 3. If the instrument..is inoperable for a period greater than seven days, a Special Report must-bei submitted to the NRC within 14 days of theievent outlining'the action ~taken,.

the cause of the-inoperability, and the plans and schedule for restoring.the system to operable status.

B. UNIT STATUS AT TIME OF EVENT.

l On 11/08/90, Unit 2 was in the Run mode at an approximate power level of 2436; CHWt (approximately 100% of rated thermal power).

I C. DESCRIPTION 0F EVENT On 11/08/90, at approximately-1300 CST, the reactor building accident range radiation monitor was declared' inoperable due to an erratic output. ,

Deficiency Card 2-90-3344 was written to. document the' condition and Limiting .

Condition for Operation 2-90-346 was initiated. Maintenance Work Order 2-90-3302 was initiated to implement corrective action.

In an attempt to restore the monitor to operable status, severa1Leourses-of ,

action were pursued, including the replacement of several circuit boards in.

the system. On 11/11/90, following replacement of these electronic . . A components, and with the system still in an: inoperable status;1 technicians  ;

observed that an error code was-now being displayed on the! associated panel 1 in the Main Centrol Room. The error code indicated a detector element. failed such that the monitor's signal output was zero. Consequently, a replacement of the dete,cor would be required. Since no replacement was in warehouse.

stock at t :at time, a detector was ordered. '

The replacement detector element was received on site on.11/15/90, and work' was begun on replacing the detector element at that time. However, on 11/15/90, the accident range radiation monitor-was still inoperable and this Special Report is required.

On 11/16/90, the detector. element was replaced and. successfully functionally-tested. The monitor was declared operable and LC0 2-90-346 was terminated.

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• 1 ENCLOSURE SPECIAL REPORT 2-90-004 REACTOR BUILDING VENTILATION ACCIDENT RANGE RADIATION MONITOR. INOPERABLE FOR .

t LONGER THAN SEVEN DAYS RESULTS IN-SPECIAL REPORT ,

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D. CAUSE OF EVENT l l

l The root cause of this event was component . failure., - Specifically, .a . .

! radiation detector element failed resulting in a complete loss of output-signal.

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i E. ANALYSIS OF EVENT The reactor building vent stack radiation monitoringLsystem consists of two redundant sampling channels and an accident range monitor with one: sampling' channel. The purpose of = the system is.to monitor the activity of gaseous 1 effluent from'the reactor building stack and to proside an alarm in the' main-control room should activity levels exceed preset values.

In this event, the subject monitor was rendered inoperable by a-failed- (

detector element. The normal range detector-was operable and continued to-provide monitoring of reactor building' stack effluent. . Moreover, at 1300 l CST on 11/08/90, the preplanned alternate method of monitoring the reactor l building stack effluent was initiated. per 64CH-ADM-001-OS, " Chemistry l Program." At no time during this event- were'. activity levels . abnormally high.  ;

Based on the above analysis, it.is concluded that 'this event had no. adverse impact on nuclear safety. ~ The analysis is applicable to all power. levels. .

F. CORRECTIVE ~ ACTIONS

1. Declaring reactor building accident range radiation monitor inoperable and initiating LC0 2-90-346.

2. Initiating the prepla:'ned alternate method of reacto'r building stack radiation monitoring.

3. Initiating Maintenance Work Order 2-90-3302 to implement replacement of

, the failed detector element. -The monitor was replaced, successfully l functionally tested, and returned to service on 11/16/90, i

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