ML20083Q822

AO 73-11-10:on 731110,reactor low-low Water Level Switch Setting Actuated Above Normal Setpoint.Caused by Setpoint Drift on Yarway RE02D Sensor.Sensor Recalibr

ML20083Q822
Person / Time
Site:	Nine Mile Point
Issue date:	11/13/1973
From:	Burt D NIAGARA MOHAWK POWER CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20083Q821	List: ML20083Q818 ML20083Q822
References
AO-73-11-10, NUDOCS 8303140653
Download: ML20083Q822 (3)

Text

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!!r, Janes O'Reilly 7 AEC IIllGOFPh0SSIA,PA,

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TELECOPY TO L .0-1 ABdOR!i4LOCCURREllCE 73-11-10 FAILURE OF O!!E LOW LOW LEVEL SENSOR

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l DURIHG ROUTINE SURVEILLANCE TESTING O!! 11-10 73 AT 1509 HOURS, ONE Of TWO INSTRUMENT CHANNELS WAS FOUND TO ACTUATE AB0VE NORMAL SET POINT, BUT WITHIN THE ALLOWABLE RANGE OF TABLE 3.G,2 0F TECHNICAL SPECIFICATIONS. HOWEVER, FOLLOWIllG A RLVIEW O!1 10/12/73 - HONDAY - Of Tile SURVEILLANCE TESTING, IT WAS HOTED ,

THAT IN THE BASES OF THE TECHilICAL SPECIFICATION, Tile INSTRUMENT WAS BEYOND 175 HOFSAL DEVIATION. THERE-FOREf ASlDEFillED IN TECHNICAL SPECIFICATIONS 1,13d, WE ARE REPORTING AS AN ABNOPPA OCCURREHCE THE FAILURE OF ONE LOW LOW LEVEL set 150R. TECHNICAL SPECIFICATION 3.6.2 (PBOTECTIVEINSTRUMENTATION) STATES: "THE SET POINTS, MINIMUM HUM 8ER OF TRIP SYS1 bis, AND HIrlIMUM NUMBER OF 1HSTRtB!ErlT CREJlliELS THAT MUST BE OPERABLE FOR EACH POSITIO'i 0F REACTOR MODE SWITCH SHALL BE AS GIVEN IN TABLES 3.6.2a TO 3.6.2j.

PARAMETER HINIMUM NO. Of TRIPPED HINIMUM NO. Of OPEPABLE SET POINT

• DEVIATION OR OPERABLE TRIP s !1NSTRUMENT CHANNELS PER SYSTEMS OPERABLE TRIP SYSTEM LOW LOH REACTOR - 2 2 <5 ft. below +2.6'

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WATER LEVEL ,

iiinimum nomal water level

- THE REACTOR LOW LOW WATER LEVEL SENSORS (2 EACH PER TRIP CHANNEL) WERE ROUTIHELY TESTED. RE02D WAS FOUND TO ACTUATE AT 4' 9" BELOW MIHIR)M N0PPAL WATER LEVEL. HOPy.AL g ACTUATION IS S' 0" BELOW MINIMUM NORMAL 12.6".

SYSTEM , REQUIRED LOGIC REPARKS q

PRIMAP.Y C00LEllT 150LAT10N 2 SENSORS PER TP.IP CRAllNEL WOULD CAUSE CONTV ~ 'EHT ISOLATTM 1 SENSOR PER TRIP CHANNEL REQUIRED EMt.imuu C00L1m. .. ;1 ATION TO INITIATE FUNCTION AT START CORE SPRAY PUMPS 5 FT BELOW l Min. NORMAL LEVEL t

INITIATES CONTAINMENT SPRAY c 2 SENSORS PER CilANNEL ' WOULD CAUSE

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( O!!E SENSOR PER TRIP CHANNEL TO PARTIALLY REQUIRED FUNCTION AT l

8303140653 73111 INITIATE) ALSO HEED HIGN PDR ADOCK 05000220 $ $ FT. BELOW PDR DRYWELL PRESSURE HIN. NORMAL M' LEVE(. AND 3.5 PSI'

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p l_ p AC. IllE SYSTEMS LISTED AB0VE WOULO FUNCTION AT Ti1E REQUIRED SET POIliT. Tile CHAH!

12, TRIP UGULD OCCUR AT 4' 9" BELOW I4INIMUM NOFJiAL AND THE CIWNiEL 11 TRIP WOULD AT 5' DELOW lilllIllTl NORMAL (ACTUATING THE PROTECTIVE FUCTION). BOTil TRIP CHANNELS HUST tuf!CTION TO OBTAlti THE Pf.10TECTIVE FUNCTION NiD EVEtt if Tile 12 TRIP CHN{t(EL FUN L;tU'~.E IRST, THE SYSTEM PROTECTION FUNCTION WOULD NOT OCCUR [,

y JWTIL THE 11 TRIP SYSTEM ACTUATED. TESTING OF ALL SEH50kS IN TilIS LOGIC SHOWED tl0RP.% PROTECTIVE FUNCTION WOULD BE THITIATED AT THE DESIRED LEVEL (5' BELOW 111N11Mi NOPF.AL). THE~ INSTRUMENT, RE020. WAS RECALIBRATED AND VERIFIED TO OPERATE AT THE 5' bel.0W HINIMUM NORMAL SET POIlit.

BASED ON THE AB0VL, NO UNDUE SAiLTY HAZARL WAS PRESENTED TO Tile GENERAL PUBLIC fl0R WOULb ANY SYSTEM REQUIRED 70 FU;C10N FAIL TO FUETION PROPERLY AT ITS REQUIRE 0 SU POIllT.

• TIIE DEVIATIOlS ARE FOUND IN DIE BASES OF TiiE TECfullCAL SPECIFICATION 3.6.2 NIO ARE liOT PATT OF TIE TABLE.

P. ALLISTER BURT GENERAL SUPERI!TTEllDENT

!{UCLEAR GENERATIO!1 NitlE H1LE PQllit NUCLEAR STATION s

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Form AEC-93 (Rev. May I4,1947) AECM 0240 Note one return. For signature. Feir informatioA TO (N.m. and una) uaTiAts atMAnns RO: Chief FS&EB A0-73-11-10 NIAGARA MOHAWK - NINE MILE POINT RO:HQ (5)

RO Files D^" DN-50-220 Central Mail & Files TO (Name and unft) P4TIAL3 REMAAKS Regulatory Standards (3) The above A0 is forwarded for information.

Directorate of Licensing (13) *^" Distribution will be made by this office to the

$@i{1directrs PDR, Local PDR, NSIC, DTIE, and State TO (Name and unit) INI!!ALS REMARKS Representatives.

oAn FROP4. ( ' meAnd unst) atMARKS

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E. J. Brunner RO:I

• PHONE M OATE 3-337-1246 11/13/73 USE DTHER $4DE FOR ADDIT @NAt R(MARK $

.w..._ CPO 19711

• 445 469

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