05000455/LER-1990-007-10, :on 900928,ECCS Throttle Valve Found Closed Due to Procedural Deficiency

:on 900928,ECCS Throttle Valve Found Closed Due to Procedural Deficiency

ML20062C663
Person / Time
Site:	Byron
Issue date:	10/26/1990
From:	Gierich T, Pleniewicz R COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BYRON-90-1029, LER-90-007-10, LER-90-7-10, NUDOCS 9011020042
Download: ML20062C663 (5)

LER-1990-007, on 900928,ECCS Throttle Valve Found Closed Due to Procedural Deficiency

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii)
4551990007R10 - NRC Website

text

ex Commonwo:lth Edison

') 4450 North G2rman Church Ro:d Byron Nuctrar Station

• /

i

• ( v-J Byron, Illinois 61010 October 26, 1990 Ltts BYRON 90-1029 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.

20555

Dear Sir:

The enclosed Incenseu Event Report from Byron Generating Station is being transmittsa to you in accordance with the requirements of 10CTR50.73(A)(2)(1).

This report is number 90-007; Docket No. 50-455.

Sincerely, i

A R. Pleniewict Station Manager j Byron Nuclear Power Station RP/mim Enclosure Licensee Event Report No.90-007 cci A. Bert Davis, NRC Region III Administrator W. Kropp, NRC Senior Resident Inspector i

INPO Record Center CECO Distribution List (0659R/0077R)-

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• -~4 9011020042 901026j5 gg 4

DR ADOCK O ll g

j LICEN$EE EVENT PEPORT (LER)

F;cility Name (I)

D:cket Number (2)

Pane (3)

B ron. Unit 2 01 Sl Ol_01 01 41 51 5 1lof!Q_!4 I

Title (4)

ECIS Throttle Valve Fagnd Closed Due to Proegdural Deficionev

_LyinLD. Alt _f 5)

LER Nabg.r (6)

Report Datg_f7)

Other Facilitin_inyslyed (8)

Month Day Year Year

// Sequential /j/

// Revision Month Day Year Facility Names Docket Number (s)

/,/p _ Number ff

_N_ sher

//

NONE 01 51 01 01 01 l l

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~

019 2 IB 9 10 9 10 0 1 0 17 0l0 110 2_l6 9 10 01 51 01 01 01 I

{_

THIS REPORT !$ $UBMITTED PUR$UANT TO THE REQUIREMENTS OF 10CFR I h'ELEUI' 2t_20IA._o f. the f olleyj no) (11)

E 6

20.402(b) 20.405(c) 50.73(a)(2)(Iv)

_ 73.7)(b)

POWER 20.405(a)(1)(1)

_ 50.36(c)(1)

_ 50.73(a)(2)(v) 73.71(c)

LEVEL 20.405(a)(1)(ii) 50.36(e)(2)

,_ 50.73(a)(2)(vil)

Other (Specify l

g (10)

I I O 20.405(a)(1)(111) _lL 50.73(a)(2)(1) 50.73(a)(2)(viii)(A) in Abstract

///////////////////////,/,/,/,

20.405(a)(1)(iv) 50.73(a)(2)(li) 50.73(a)(2)(viii)(B) below and in

//////////////////////}/}/}/'/

20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(n)

Text)

Ll{LH$1E CONTACT FOR TH11_LER (12)

Name TL(LEHQN[,tgjtgER AREA CODE T. G[grich. Doeratina Ennineer Ext. 2218 8l115 21314l-l514141_1 CQlELLTE ONE LINE FOR EACH CQM20HERLIAILDRE DESCRIBIQ IN..THit REPORT (13)

CAUSE

SYSTEM COMPONENT ENUFAC-REPORTABLE

/

CAUSE

SYSTEM COMPONEN. l M**/JFAC-REPORTABLE

_ _TURER TO NPRDS (URER 20_NERQ1_

l l I l l l 1:

1 l l 1 1-l 1 l

I l I l _ _ L l_

1 I I I

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$1)ff.LLtENTAL REPORT EXPECTED (14)

Expected Month.j_Dar_Lnar

$ubmission Date (15)

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_lYt1_II.Lyth 10mRleit_fJLPLCIID_SUSMISS10N_0ME) x LN0 I

I I I l - --

ABSTRACT (Limit ~ to 1400 spaces, i.e. approximately fif teen single-space typewritten lines) (16)

On 9-28-90 at 2130, during performance of Technical Specification $urveillance 28v5 0.5-2.$1.2-1, " Safety injection Pump Cold Leg injection Flow Test", it was found that the RC$ Loop *A" branch indicated tero flow while the associated RCS loops "B, C and D" branches Indicated higher than expected flowrotes. The test was suspended and a preliminary investigation revealed that the Loop "A" Cold Leg Safety Injection ($1) (SQ) Line Throttle Valva, 2518822A was closed.

This_valrr is an Emergency Core Cooling System (ECCS) Throttle Valve and is required to be h ked in a pre-set throttle! open position to provide a balanced flow to each of the RC$ cold legs. The valve is believed to have b;en closed to support maintenance work on a dif ferent $1 valve during the previous outage and the valve was not placed in the correct throttle position at the conclusion of this work.

, A special procedure will be written to balance the branch line flows for intermediate head $1 to the cold legs.

Subs:quent to the flow balance all four of the valve's locking devices will be welded into position to prevent imp.'oper positioning in the future.

This. event is being reported pursuant to 10CFR50.73(A)(21)(B) as any operation or condition prohibited by technical Specifications.

(0659R/0077R-2)

i LIEENSEE EyiMI_.lt[ PORT (LER) ftXT CONTINUATION Form Rev 2.0

.FACIL!fY NAME (1)

DOCKET NUPSER (2)

LER NupeER (6)

Pane (3)

Year

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Sequential

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Revision fff fff

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Number

///

Numbar_

Jvron. Unit 2 0 l 5 1 0 1 0 1 0 l 41 51 5 910 01017 0 l

,.Q, 0 12 0F 0 14 TEXT Energy Industry Identification System (E11$) codes are identified in the text as (XX) l A.

PLANT C04Difl0NS PRIOR TO EVENT:

tvent Date/ Time 9-28-90 / 2130 Unit 1 MODE 1

_fower Operation..

Rx Power.321.__

RCS (AB) Temperature / Pressure _Hormal Optta11g_

Unit 2 MODE.1__

[!algelad Rx Power _QL.

RCS (AB) Temperature / Pressure 80 /

0 6.

DESCMEI1QtLQL EYEMIl 1

On September 28, 1990 at 2130 with Byron Unit 2 in refueling outage with the core off loaded, Intermediate Head $afety injection (SI) (9Q) to Cold Leg Loop A Throttle Valve 25!8822A, was found in the closed position. This valve is required to be throttled open to provide balanced flow to the Reactor Coolant System (RCS) (AB) cold legs. The valve was discovered closed during an !$1 check valve stroke vertf tcation H

which found aero flow on the loop A branch line. It is speculated that this valve had been closed since the previous refueling outage in February 1999, following its use as an isolation point for maintenance work on a downstream check valve.

l No other ECC$ equipment on these branch lines was degraded at the time of discovery of the secured closed valve. There were no Safety System Actuations resulting from this event, nor did any conditions exist that wovid require mitigation by ECC$. Notification of this event was made within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> at 0106 on 9-29-90 in accordance with 10CFR50.72(b)(2)(1). The plant remained stable throughout this event.

C.

CMSC_0LLVLH1:

l.

Review of available data indicates the most recent manipulation of this throttle valve to the closed l

position occurred on or around February 12, 1989. The throttle valve, 2$18822A, was most Ilkely used as an j

isolation point for work on RC$ Isolation Check Valve, 2$18819A. On December 19, 1988, Nuclear Work l

Request (NWR) B63373 was written to repair a seal weld on the bonnet of valve 2518019A. To support this L

' work activity, Out-of-$ervice 89-2-0622 was prepared which presumably incorporated valve 2$18822A as an l

1 solation point. The Out-of-$ervice (005) documentation was unavailable for review because 00$ documents

,l are routinely retained for only six months. NWR B64048 was written on January 12, 1989 to obtain the "As 12 Found" valve position using a micrometer to measure the valve stam position to support the Operating Department in taking this Out-of-$ervice. Following maintenance i the check valve, this NWR would also support the throttle valve's return to service to its "As Found" position.

Shif t authorization to perfotu en initial measurement of the throttle valve's stem position (As Found")

was granted on January 14, 1989. The initial measurement of the throttle valve's stem position as compared to the top of the handwheel nut, indicated the stee to be 0.095 inches from the nut. This measurement was I

carried out per the NWR's work instructions. At 1900 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br /> on January 14, the out-of-service was implemented. On January 16, Shift autherlaation was granted to begin repairing the seal weld on the check valve. This work was completed on January 24. The out-of-service remained in effect.

(0659R/0077R-3) a

i Lli[H1EE EVENT REPORT (LER) TEXT CONTINUATION rgretRev 2.0 t

' FACILITY mME (1)

DOCKET NVPSER (2)

LER NupeER (6)

._... P a 9t_O )

ffj/

Sequential

//

//j Year

/

Revision g//

///

Number

/

Number Ryron _ Unit 2 0 1 5 1 0 1 0 1 0 1 41 51.5 9 10 01017 01 0 t) 13 0F 0 14 TEXT

. Energy Industry Identification System (E!!$) codes are identified in the text as (XX)

On February 11, 1989, the Technical Staf f began performance of surveillance 2BVS 0.5-2.$1.2-1 " Safety Injection Pump Cold Leg Injection Flow Test" at 1024 hours0.0119 days <br />0.284 hours <br />0.00169 weeks <br />3.89632e-4 months <br />. The performance of this surveillance would have necessitated a temporary lif t of the out-of-service on the 2 SIB 822A valve in order to verify flow past the 2518819A check valve. No temporary lift documentation is available. This surveillance was satisf actorily completed at 0430 hours0.00498 days <br />0.119 hours <br />7.109788e-4 weeks <br />1.63615e-4 months <br /> on February 12. Flow was verifled past the check valve and therefore through the throttle valve.

It is speculated that the throttle valve was reclosed upon termination of the temporary lif t.

On February 13, 1989 Mechanical Maintenance and Operating personnel were dispatched to reset the throttle valve to its "As Found" position per NWR 64048. A mechanic measured the stem position, again compared to the top of the handsheel nut, to be 0.090 Inches from the nut.

Upon completion of these activities, the out-of-service was cleared at 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on February 13 by Operating Department personnel. On February 18, 1989 at 1631 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.205955e-4 months <br />. Operating personnel performed survel11ance 280$ 5.2.g.1-1 which verified the mechanical stops were in place. This surveillance was done to complete NWR B64048 testing requirements, but did net verify valve position.

It is not positively known whether the measurement of 0.090 inches was made with the stem above or below the nut. It should be noted that 0.090 inches in the negative direction (stem inside the nut) represents

.the fu11-closed position of this throttle valve. This is the position the valve was found on September 28, 1990.

During intervlee, the mechante indicated that from the work instructions given, he would not have known i

which direction the valve stem should have been measured from with respect to the handwheel nut, and it was possible that he would have measured this in the negative direction. The mechanic could not recall exactly what happened because this activity took place 19 months ago.

I D.. SMUyRIAL151$:

The safety of the plant and public was not jeopardised by this event. An analysis was perfonned by Westinghouse using the system flow data collected during the surveillance with Branch A Cold Leg Injection Throttle Valve, 2 SIB 822A' closed. This analysis indicates that less water than assumed in accident analysis would have been infected, had the Safety. Injection System been challenged while in this

- configuration. Thg, rCCS configuration was analysed from large and small break LOC /. long-term post LOCA cooling, non-LOCf-.entainment integrity and system operational standpoints. In **i1 cases, the Peak

. Cladding Temperature remained well below the limits of 10CFR50.46. This analysis included all worst case design accidents as described in Chapter 15 of the UFSAR. The analysis concluded that no regulatory or design limits were exceeded with 2$18822A closed.

(0659R/0077R-4)

e LICENSEE EVENT REPORT fLER) TEXT CONTItluATION fore Rev 2.0 i

DOCKET NUPSER (2)

LER NUPRER M1 Pag _f 31

.FACJLITY @ME (1)

Sequential Revision g//

g//

Year

/

Nygher

/

Number

,jyrgn. Unit 2 0 l 510 l 010141515 9 10 01017 QJ 0 0 14 0F Lji TEXT Energy Industry Identification System (t!!$) codes are identified in the text as [XX)

E.

EORRECTIVE_ ACTIONS:

A Unit I containment entry was made shortly afW da Unit 2 discovery to ensure that the Unit I valves were in their proper throttled position. The valves w:re found to be throttled in accordance with preoperational values with the exception of one valve which was slightly more open than required.

To correct the immediate problem of throttle valves 2$18822A wrong position. Technical Staff personnel performed an ECC$ Cold Leg injection Flow Balance on Unit 2 on October 1,1990 ($PP 90-70) to re-establish correct flow through all loops. Due to one of the differential pressure gauges being found out of tolerance upon post-test calibration, a flow verification test ($pF 90-73) will be performed to ensure all Technical.$pecification (3/4.5.2.h) requirements are met. In addition, this flow verification test will be performed for the High Head Cold Leg injection loops and Hot Leg injection loops on Unit 2 prior to entering mode 5 during the current refueling outage. Upon satisfactory results, all 12 safety injection system throttle valve's locking devices will be tack welded into place. The same flow verification test will be performed on all three injection flowpaths on Unit I during refueling outage BIR04 These ECCS throttle valve's locking devices likewise, will be tack welded into place upon satisfactory results.

AIR's90-257 and 90-258 will track these actions.

Byron station has procedures in place to address ECCS throttle valve measurements. These procedures, BVP

.900 4 for Unit I and BVP 900-5 for Unit 2, instruct personnel on correct valve stem measurements, locations, and directions. The original versions of these procedures dif fered slightly in the techniques used in measuring. Both procedures will be revised te provide a uniform method of measuring the throttle valves positions. In addition, surveillances 1/200$ 5.2.g.1-1 were revised on August 30, 1990, to incorporate the use of the aforementioned BVp's to verify the ECCS throttle valves are in their proper positions. AIR 90-255 will track these procedure revisions.

The Technical Staff will identify, on a system basis, all throttle valves which have critical settings that should be measured using a m:crometer. Appitcable measuring and tracking procedures will be developed, as needed. The Essential serviae Water ($X), Component Cooling (CC) and Containment Spray (CS) Systems are known to have throttle valves and are being reviewed at this time. AIR 90-256 'will track this invest'gation.

F.

f1EHQU$ OCCURRENC[1!

There are no previous occurrences of an ECCS throttle valve found in a closed position..

G. - (0Mp0NENT FMLURE DATA:

No components f ailed during this event.

l L

(0659R/0077R-5)