ML20006E395

LER 89-010-01:on 890303,automatic Depressurization Sys Permissive Switch Found W/Setpoint in Excess of Reject Limit.Caused by Setpoint Drift.All Static-O-Ring Reactor Vessel Level Switches Will Be replaced.W/900214 Ltr

ML20006E395
Person / Time
Site:	LaSalle
Issue date:	02/14/1990
From:	Diederich G, Jacklin N COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-010-01, NUDOCS 9002230049
Download: ML20006E395 (6)

Text

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, .: _l Y 1' Commow oalth Edison

- LtSalle County Nuctrar Station ,

.4 . Rurat Route #1, Box 220

l~ 3- Marseilles, Illinois 61341 N O  : Telephone 815/357 6761

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February 14, 1990 l

Director of. Nuclear Reactor Regulation U.S. Nuclear Regulatory Coasaission Mail Station F1-137 j Washington, D.C. 20555

Dear Sir:

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Licensee Event Report #89-010-01, Docket #050-373 is being 9 sutaitted to your office to supercede previously submitted Licensee Event Report 89-010-00 which was reported pursuant to NRC 1.E. Bulletin 86-02, " Static-O-Ring Differential Pressure Switch."

NO G. J. Diedert h hlstationManager LaSalle County Station GJD/NWJ/kg ~l Enclosure I

.xc: Nuclear Licensing Administrator NRC Resident Inspector NRC Region III Administrator l

INPO - Records Center l l

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I ll pff223OO49 S ADOCK O 9$0 hob 73 PDC . ') ,'f'!

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p LICENSEE EVENT REPORT (LER) Fonn Rev 2.0 Docket Nunber (2) Pace (3)

Facility Name (1)

L W 11e County Station Unit 1 01 51 01 01 01 31 11 3 1lofl0l5 Title (4) "

Setool'nt Drift of Low Level Confinned Automatic Depressurization System Pennissive Switch LER N m r (6) Report Date (7) Other Facilities involved (8)

Event Date (5) Facility Names Docket Wweer(s)

Day Year Year / Sequential Revision Month Day Year Month

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// Noter r

01 51 01 01 01 1 I L

01 3 01 3 81 9 81 9

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0l 1 0l2 11 4 91 0 0151010101 l l l TH15 REPORT IS SUBMI1TED PUR$UANT TO THE REQUIREMENTS OF 10CFR (Check one or more of the followine) (11)

MODE W 3 20.402(b) 20.405(c) _ 50.73(a)(2)(iv) _

73.71(b) 20.405(a)(1)(1) 50.36(c)(1) _ 50.73(a)(2)(v) _

73.7t(c) .;

i. POWER _ _

50.36(c)(2) 50.73(a)(2)(vil) ]L Other (Specify-L LEVEL 20.405(a)(1)(ll) _ _

50.73(a)(2)(vill)(A) in Abstract (10) 0l0l0 _ 20.405(a)(1)(lii) _

50.73(a)(2)(l) _

50.73(a)(2)(vill)(B) below and in

/,/,/ ///,/,/////,/,/,///,/,/,/,/,/,/,/ 20.405(a)(1)(lv) 50.73(a)(2)(ll) ,_,

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50.73(a)(2)(lii) 50.73(a)(2)(x) Text) voluntary L '/,'

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'/'j'j/ 'j'j'j'j'j/'/'/// _ 20.405(a)(1)(v) _ _

LICENSEE CONTACT FOR THIS LER (12)

TELEPHONE NUISER Name AREA CODE Ned Jacklin. Technical Staff Enoineer, extension 2397 8 l 1 15 315171-l6171611 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE ' SYSTEM COMPONENT MANUFAC- REPORTABLE CAUSE SYSTEM COMPONENT MANUFAC- REPORTABLE TURER' TO WPROS TURER TO WPRDS=

X 5I B l l Li S SI31812 Y I l i I I l l i I I I l l l .

I I I I I I I SUPPLEMENTAL REPORT EXPECTED (14)

Expected Month l Day i Year Submission lyes (If yes. complete EXPECTED SUBMISSION DATE) X l NO Ll ll ll ABSTRACT (Limit to 1400 spaces, i.e approximately fifteen single-space typewritten lines) (16)

At 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on March 3,1989 Reactor Vessel Low Water Level 3 Confinned Automatic Depressurization System (ADS) Pennissive Switch LS-1821-NO38A was found with its setpoint out-of-tolerance in excess of its Reject Limit. The failure was in the conservative direction. This discovery was made during the perfonnance of a routine surveillance while Unit I was in Mode 3, Hot Shutdown.

Because its "As Found" setpoint was still within Technical Specification limits, LS-IB21-NO38A would have properly perfonned its ADS low level confinned function as required in the event of low reactor water level.

50R differential pressure instruments which exceed their Reject limits are rejected from further service and replaced.- The switch replacement and calibration were conpleted by 2245 hours0.026 days <br />0.624 hours <br />0.00371 weeks <br />8.542225e-4 months <br /> on March 4, 1989. The rejected instrument was disassenbled and inspected to attengt to detennine the root cause of failure. No definite cause of failure could be detennined. Nothing abnonnal was found. The level switch which precipitated this event will be replaced by an analog trip system during the fourth refueling of Unit I, currently scheduled to begin in the Spring of 1991.

This event is voluntarily reported to the Nuclear Regulatory Comnission in conpliance with the requirements of Inspection Enforcement Bulletin 86-02 (IEB 86-02).

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Fom Rev 21 j iFACILITY NAlt (1).

Lire *KEE EVENT REPORT (LER) TEXT CONTINUATION DOCKET NUPSER (2). LER C R (6) Pace (3)- j e . Year g/// Sequ;ntial // Revision i thaber~ /j/j/

J /// / Number _ -$

lie County Station' unit 1.*

O l'5 l'0 1 0 l'0 l'31 il 3 819

- 0 l l'l 0 - 0 l- 1 01 2 0F 01 5 f '

' , TEXT . . Energy Industry identification System (Ells) codes are identified in the text as [XX]-;

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PLANT [ AND SYSTEM IDEWilflCATION i

General Electric - Bolling Water Reactor i

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Energy Industry identification System (Ells) codes are identified in the text as (XX].

l A. CONDITION PRIOR TO EVENT Unit (s): l, Event Date: 3/3/89 Event Time: 1000 Hours- ]

3 Mode (s) Name: Hot Shutdown . Power Level (s): '05 Reactor Mode (s):

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, 8. DESCRIPTION OF EVENT Reactor Vessel (NB)'[AD) Low Water Level 3 Confimed Automatic Depressurization System (ADS) (58]

' Pemissive Switch LS-1821-NO38A was found with its setpoint out-of-tolerance in excess of its Reject.

Limit in the conservative direction.. This discovery,was made at 1800, hours on March 3, 1989,.during the perfomance of 'LaSalle Ins'trument Surveillance LIS-N8-106, " Unit 1 Reactor Vessel Low Water Level .

Confimed Automatic Depressurization System Pemissive Calibration." Unit I was in Hot Shutdown (Pode

3) at the time.

The' subject instrissent tripped as expected due to low reactor level during the reactor scram which.

occurred at 2302 hours0.0266 days <br />0.639 hours <br />0.00381 weeks <br />8.75911e-4 months <br /> on March 2, 19894 (See LER 373/89-009-00.~) .

The "As Found" setpoint for LS-1821-N038A was 55.2 inches of water colisun ("WC), corresponding to 24.6 '

' inches of indicated reactor water. level ("Ihr). The desired setpoint (at atmospheric pressure) of this

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switch is 19.40 "ItiL (58.9 "WC) with a tolerance of +/- 0.71 " Inn. (>/- 0.50 "WC), Action Limits of +/-

3.% ."Init (+/- 2.80 "WC), and Reject- Limits of +/- 4.10 "Indt (+/- 2.90 "WC). The upper Reject Limits is ' i

' 23.5 "It#L, so the "As Found" setpoint exceeded the Reject Limit by 1.1 "Infl. :The Technical' Specification Limiting Condition for operation is >/= 11.00 "IniL (</= 64.84 "WC) with a Nominal' Trip Setpoint of 12.50 "InlL (63.78 "WC). The infonnation in this paragraph is graphically displayed in

-i Figure 1. l LS-1821-NO38A is an SOR differential pressure switch of a type.which displays a shift in setpoint when

> placed at an elevated static pressure. This switch functions to confirm a low level in the reactor vessel and allow operation of Olvision 1 of ADS. This function was not inpaired by the out-of-tolerance ,

Jsetpoint.,

This event is voluntarily reported to the Nuclear Regulatory Comnission in compliance with the

. requirements of Inspection Enforcement Bulletin 86-02 (IE8 86-02). Personnel error did not influence

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fe the cause or severity of this event. The actions taken by plant personnel in response to this event were timely and appropriate.

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LICE *ME EVENT REPORT (LER) TEXT CONTINUATION Fom Rev 2.0 DOCKET NUSER (2) LER NHSER (6) Pee (3) ';

FACILITY NAME (1)

Year / . Sequential //j/ Revision k-J' - g//j/

/ Neter fM/ Nueer_ [

b 0 l'1 1 0 0 l-- 01 3 0F 01 5 h.

leMlle County Station Unit l' 0 l 5 1 0 1 0 1 0 l 31 71 3 8l9 - - 1

,> TEXT' Energy Industry identification System (Ells) codes are identified in the text as (XXJ C. APPARENT CAUSE OF EVENT This event was doparently caused by setpoint drift. After an initial actuation of a SOR dP switch, subsequent actuations (within a short time after the initial trip) tend to occur at a low differential pressure (conservative direction). This may also have contributed to the calibratton'setpoint being-foundintheconservativedirectionoutsidetherejectband.

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-The instrument wa: disasseeled and inspected at the station.to attenyt to detennine the cause of-fallure. No damage or other abnormalities were noted.

D. SAFETY ANALYSIS OF EVENT

? This event did not degrade plant safety. ,

LS-1821-#038A would have functioned as required in the event of low water level in the reactor vessel.

'Its "As Found" setpoint was within Technical Specification Ilmits. Also, since a vessel water level of L -129 " Inn. must occur before ADS automatically initiates, it is certain that this switch would have tripped by the time reactor water level became low enough.to generate an initiation signal. i h

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l l E. CORRECTIVE ACTIONS I 3

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1 As required by Comonwealth Edison's SOR Long Tenn Action Plan, SOR differential pressure switches which driftbeyondtheirrejectlimitsareconsideredtechnicallyinoperable. Accordingly LS-1821-N038A was

' declared inoperable at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on March 3, 1989.

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' The'inoperability of this-switch rendered the trip system of ADS Division I inoperable. Technical

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l' Action i -Specification 3.3.3 requires the ADS trip systems to be operable in Plant Conditions 1, 2 and 3.

' Statement C of this specification requires that an inoperable ADS trip system must be restored to l

operability within seven days, provided the other ADS trip systems, High Pressure Core Spray (HPCS) l- )

l [9G), and Reactor Core Isolation Cooling (RCIC) [8N] remain operable.

1 h l The Consnonwealth Edison SOR Long Tenn Action Plan requires that SOR instruments which exceed their' Reject Limits be rejected from further service 44d replaced. Work Request L88000 was written to replace L

the rejected instrument with another identical instrument which had been certified for use at LaSalle.

L The' switch replacement and calibration were conpleted by 2245 hours0.026 days <br />0.624 hours <br />0.00371 weeks <br />8.542225e-4 months <br /> on March 4, 1989 and ADS Division I was declared operable, within the seven days allowed by Technical Specification 3.3.3.

p The rejected instrument was disassenbled and inspected at the station to attengt to detennine the root l:

.-cause of failure.

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n LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Form Rev 2.0 FACILITY NAME (1) DOCKET NU SER (2) LER NU SER (6) Pace (3)

Year- /// Sequential /jjj/

/ Revision j/jj

// Nueer /// Nweer__

LaSalle County Station Unit I- 0'l 5 1 0 l'0 l 0 1 31 71 3 8l9 - 0l110 - 0l 1 01 4 0F 01 5 l-TEXT Energy Industry identification System (Ell 5) codes are identified in the text as [XX)

'E. CORRECTIVE ACTIONS (Continued)

Modifications are planned to remove all SOR reactor vessel level switches at LaSalle and replace them with analog trip units. The analog trip units were chosen partly because of their setpoint stability.

They are expected to inprove the perfonnance of the Reactor Vessel Wter Level Sensing System. The level switch which precipitated this event will be replaced under modification M01 1-87-097 during the fourth refueling of Unit 1, currently scheduled to begin in the Spring of 1991. Action item Record AIR 373-123-87-00003 is tracking the completion of this modification. ,

F. PREVIOUS EVENTS l: LER Wunt>er Title t

374/96-007-00 Excessive Static-0-Ring Pressure Switch Drift 374/96-011-01 Failure of 12.5" DP Level Switch to Respond to Low Level ,

374/96-019-01 Reactor vessel Low Level Confimed ADS Pemissive Switch Out of Tolerance Due to Setpoint Drift 373/87-013-01 Automatic Depressurization System Low Level Confimed Switch Setpoint Found Out. of j.

Tolerance Due'to Setpoint Drift 374/87-011-01 Residual Heat Removal Peip Minimun Flow Bypass Differential Pressure Switch found L

l- Out of Tolerance Due to Setpoint Drift 373/88-028-01 Setpoint Drift of Reactor Vessel Low W ter Level Switch 373/88-029-01 Setpoint Drift of Low Level Confinned Automatic Depressurization System Permissive Switch 374/88-005-01 High Pressure Core Spray Minimun Flow Bypass Flow Switch Out of Tolerance Due to L Setpoint Drift 374/88-013-01 Low Pressure Core Spray Mininen Flow Bypass Differential Switch Found Above RejectionLimit 374/88-015-01 Residual Heat Renoval Pung Minimum Flow Bypass Differential Pressure Switch Found l Out of Tolerance Due to Setpoint Drift L 373/89-003-00 Setpoint Drift of Reactor Vessel Low hter Level Switch I

L 373/89-005-01 Main Steam High Flow Switch Outef-Tolerance Due to Setpoint Drift '

l 373/89-008-01 Setpoint Drift of Reactor Vessel Low Wter Level (Level 2) Switch 374/89-004-01 2A Residual Heat Removal Minimum Flow Bypass Switch Found Greater than Reject Limit During Surveillance Testing 374/89-006-01 Setpoint Drift of Low Level Cor. firmed Automatic Depressurization System Pennissive Switch L

G. COMPONENT "AILURE DATA i

Manufacturer Nomenclature Model Number MFG Part Nueer 50R Inc. Differential 103-AS-8212-WX-C I A- NA

! Pressure Switch JJTTX6 l: .

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> p.y , Form Rev 2.0 =j J LlWE IM REPORT (t1R)' TEXT COWilNUATION 'l DOCKET NUSER (2)' LER NilSER (6) Pee (3)

FACILITY NAME (1)

Year. ' fjj/

// Sequential /gj . Revision .i

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' /// Neuber = /// Neuber

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' Alle County Stat ion Uni t 1. . . ' O' l 5 1 0 1 0 1 0 1 31 71 3 819 - 0lIl0 - 0 11 1 01 5 0F 01 5 ll 1 EXT . Energy industry identification System (Ells) codes are identified in the text as [XX). '

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Inches Of Indicated  ;

Reactor Water Level-i "As Found" Setpoint-(Atmospheric Pressure)- + 24.60" 23.50" g - - -

5 23.36" ,

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> 20.11" Desired .i Reject . Setpoint F-Action Tolerance 19.40" Setpoint .j Limits = Limits e

. Atmos. Press .q l . . . .

> 18.69" .

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L.  ; 15.44" 15.30" 1 q

.i Calculated Trippoint (Rated Pressure)  ; 13.39" Technical Specification Nominal Setpoint. +- 12.50" l Technical-Specification Limit > 11.00" )

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[ Figure 1: Static 0-Ring Setpoint Information :l 1

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