ML20084H868

AO BFAO-7422W:on 740404,damage Discovered to HPCI Turbine Steam Supply Piping Hanger Support Rods,Piping Restraints, Steam Supply Valve FCV 73-16 Limit Switches & Turbine Inboard Bearing Pedestal.Cause by Slug of Water

ML20084H868
Person / Time
Site:	Browns Ferry
Issue date:	04/12/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
AO-BFAO-7422W, NUDOCS 8305060074
Download: ML20084H868 (4)

Text

C *

[j u

4

()

u TENNESSEE CHATTANOOGA, VALLEY TGNNEOSSE AUTHCPITY r"T T " ",\  :

37401 J \

.:- T

,,7,-T..TT.

. a J Z,  ; ,,

S. N, / <,

b .' a.

---)

Aprp. 12, 1974 p'

~ J

,ofNP II U h Y:\ -g SWi ru m e-

m. %, o ru :2

(,(iVi ,5

~ ~ , s. ,/c

, ,t, 1,g [q#I .3p' u- ' d -  :)

<. u. s c.

~ > , ,

r Q,\cjp/yh/ p rM .. oA l'.r. John F. O' Leary, Director - t '

Directorate of Licencing Office of Reculation -

U.G. Atomic Energy Co:=icsion

'dachington, DC 205k5

Dear I'r. O' Lealy:

TEi!! ESSE 3 VALLEY AITEORIT? - BRO'.:iS FEPJrf liUCL2R fit.IIT U:IIT 1 -

DOCiST I!O. 50-259 - FACILTTI OP3RATII;G LICHIS3 DPR IEOR1.L OCCUrd2:Cij R PO:iT BFAO-7h22*d The enclosed report is to provido deteilc concerning failure of the HPCI turbine cteen cupply piping hen';cr cupport roda, piping restrain c, stern cupply valve (FCV 73-16) liuit cuitches, cnd tur'oine inboard bearing pedertel. Thic event occurred on Brouns Ferry ;;uelcar Plent unit 1 on /pril 4,197::, cnd is cubnitted in accordence uith App:nd'.n 1. t , 2cculat:-,- Cu' d: 1.16, 20.-ision 1, Or.t:ter l';73.

Very truly yourc, TEI!1ECSEE VisLIZI AUTHORITY C h0 ./*s fs';,', k ' ,/ '

• 1

/

/g 12. F. Th'orns

, Director of Pouer Production Inelocure CC (2nclocure):

I;r. I!or.cn C.1:ccclcy, Director Region II Regulatory Operationc Office, USAEC 230 Pecchtree Street, D!. , Suite 818 Atlenta, Georcie. 30303

/

l' I < (l,b 1 w h/

4 % D G .O YC sl4(~h 1

8305060074 740412 #

i PDR ADGCM 05000259 I

PDR ,

COPY SEN1' REGION ,

.)

AhMORFAL OCCURRE!!CE n:'FO:lT

, im 4

(v)

(O)

Report no.: BFf.0-7422U Report Date: 1.pril 12, 1974 ,

Occurrence Date: !.pril h, 1974 Fccility: Brovnc Ferry lluclear Plant unit 1 Identification of Occurrence Failure of the HPCI turbine steen ::upply pipinc hanger cupport rode, pipin; rectrein9:,

ctem cupply valve (FCV 73-16) linit :nritchec, and turbine inboerd beering peccatal.

Conditionc Prior to Occurrcnce The reactor vac in a hot chutdoun condition. The reactor proccure une cppronir.tel-850 pai vith the outboerd HPCI ctern ::upply primary containment icolation velv closed.

.Descrintion of Occurrence The HPCI turbine steen cupply vac icolated on 1.pril 2, 1974,. for nainten:nce cctivitics on the ;1cnd ccel condenrer condencate pturp notor en' e lor l.inc cle"-

coc1 condencer head cachet uhile the reactor ucc in operation. Icelation vec accor.plished by clocure of the outboerd primer / contninnent icolation velve (1-73-3).

The inboard velvo (1-73-2) remained open thuc, a portion of the line was enpoce to reactor stcen.

The unit cerc=ed at 6:55 p,.u. on April 3 due to a cenerator lota rejection tri; cauced by tornado dnnage to trene.niccion lines. On 1.pril 4 ct eppro: 70.tcly 2:00 a.u. , while the unit unc still in the chutdo.m condition, the cteen cuppl; line urn chcrried with stem to the ste.nn nunnN vr.ha (PCV 77 MI M incent tn ^

the turbine by opening the outbotrd i::olation trive (1-73-3). l.hprobts.tely'E pai eteen preccure wac availcble for charging the line. Uhen the line une chexced, it custained enecccive laterel end vertied novenent in the portion ocuucen the outboerd containment icolation velve end the ctern cupply velve adjacent ::

the turbine c:: the result of c. cuppositioned slug of water. The dera o ucc diccovered at approninately 7:30 p.m. on 2pril 4 by en in::pection ter:- ho :tr nr.hin'; a routine chech of piping ::hoch errestorc. Ho attempt has been rado to opere.tc the HPCI in the interin.

Desinnetion of I' meront Crure of Occurrence The single apparent cauce of the occurrence ucc n clug of unter crented by stcm condon::cd in the steen cupply line upstream of the princr/ contnirc.cnt outbocri isoletion velve (1-73-3) tovin ; doun the pipo vhen it rac chrrged. 1. contribu-ing factor to the creation of a unter voluno in the piping vac the errangerent of valves end their positioninc. The princr/ containment outboerd isolation velve (1-73-3) van tecced chut on !.pril 2 ucing the nornal hold order clearence procedure to ellou repair of the ;1PCI turbine gland ccal condencer loc.hing head crchet =d replacenent of the gland condenser condensate pu p notor. Tcccing the outboerd velve for c1rrance procedure is nornel beenuce it is outside the dry..cll, thuc accenciL for tcccinc. The inboard priner/ containnent isolation w ce (1-73-2) recained in the open pocition. Thic vclving clicnnent allo ci steen from the reactor to condence end forn a unter volune upstrec= from valve 1-73-3 When velve 1-73-3 vac opened te varn the stemline, the valve openin:: contact:

senled in accorda.nce with desir;ned intent and the valve opened ell the uey.

l

& g.

Analycic of Occurrence The derage resulting from the occurrence concicted of the follo'. ring:

A. Piping adjacent to the turbine -

1. Three vertical pipe hancer rod (7/8" dicmeter) ucre broken and one rod was bent.

2. Tuoricidvallrestraintscustainedbendingand/orbuchling.

3. One hydraulic restraint elevic uas chcared off end it: accociated un11 plate una buckled.

4 Tuo hanger lugc atteched to the pipe ucro clicht2,y deformed.

5. A vell enchor accc foly for the turbino diccharge pipe vac stuck by the stecnline end the ecce-bly vac buchied clight3;r.

B. Turbine - The inboard turbine journal bearing cact-iron pedectc1 fractured in tuo locations.

C. Stocm supply valve adjccent to the turbine (FCV 73-16) - The overhuns plactic limit cuitch on the top of the notor operator unc brohen. There unc no relence of radioactive stern or atterial as a result of thic occurrence.

Corrective Action Follouing discuccionc of the occurrence, uritten in::truction: (:FI 15.2-A) ucc prepered uhich deci ncted the cecyc of the vorh to be performed includin3 corpnen; inspection end nondestructive tectin;.

A representative of the turbino nanufacturer ucc celled to the cite to essict in the invectigation end corrective cetion. . visuel incpection of the eter:. cupply piping from the reretor veccel co the turbine nac conducted. There - cro no indicttions of pipe derece or dict rbence incide the dry. ell. The firct ci r C denece ucc on the caccad pipe henser ou: cide the drynell rnd beerne uore enue.;cive in the direction of the turbinc. The drjucil pcnctrrition,1 rge ceicnic-rct cc:c force rectrnint outside the dr/ucil, the outbc?rd pri;r/ conteirrent icole t:.;.:

velve, and the first hanger eccenbly on the pipe ucre in good condition. Ill ,iping inculation vac renoved from the :: term cupply pipin; fron the dry rell ponctration to the turbino flan;c. "c.c inculation vec c1co removed fron the upper turbine encing. The uninculated pipo unc thorough 2,y inspected vicuelly for crechc, dictortions, cnd desage of any r/pc. All pipe ucid: ucre liquid penetrent checked and colected ucid: ucre ultreconically checked. Five pipe ucida ucre radio;rrphed and revicued for unacceptable defects or derace. The lu.;c attached to the pipin; ucrc licuid penetrrat cheched end edjacent pipe crenc ::cre liquid penetr:nt cheched. Ultrasonic pipe vall thichnoc mencurcrents vere tr. ken on the circumference addncent to the turbine flance connection. Ultroconic urll thic"necc r.tec:nu'cr.cate of the pipe inline uith the ubitu:1 uc11 chie:=ccc 1..cacurcJ circunferenticily ucre taken from the turbine pipe fl'nce upctrec= to 7CV 75-16.

9 '% '

.. . e )

Correctivef.ction(continued) .

Circunferentiel ultraconic vall thicknecc mencuremente ucre taken on the pino upctreel.1 of the first c1bou fron TCV 73-16. I.11 creac uhere there vac eny cunnicion of denece or poccible derece vero nondectructive tected. There were no dene m pipe ucido diccovered end the piping integrity unc cound. All pipe vall thichnecccc vere trithin accepttble limitc. The brohen henger rode, cupport lu;c, and anchor platcc were replc.ced .rith neu raterial. The broken turbine pcdecb 1 nac replcced with a neu podent:1 from the unit 3 turbine. A visual incpection vnr conducted of the uninculated turbine encing end velve caning. Cecing lucc "'c 4 sh cnte with inboard podent 1 ucre liquid penetren' c tacted. A 1erge crcc of the cccing adjacent to the pcdectc1 nac liquid penetrent tested. Uo denece ucc found by the nondcatructive testing. Both cides of the stop velve flence ucre licuid penetrent tested, and no crecha or densge ucre found. Cther inspections on

, . turbine to ptp couplingc, journr1 berrin;c, chaft accic, chnftc, p=n thrur'.

bearing, end other pu p-turbino coroonente vere conducted. The only denece c : a triped thruct bearing on the turbine which did not occur during thic incident. ..

new thruct becring cacc=bly unc inctclied. -

In cunner,/, the nondestructive tccting choved the turbine end it: piping to '.-

integrent c.nd cl1 doncGo to pipe cupports end rectraint vac corrected. The .urcine pedcctel brechrce was the only der.ece cucteined by the turbine cc r recult Of:

the clug of utter end it uc.c reycired by neu pc.rtc replace-ent. The ceuipne n una properly recligned cad ecce.mbled in prepa*ntion for post meintenrnce tent ~~.

A uritten post me.intenence tent progren uns prepared end perfored, ifnich cec ~ red that the 1equipment vac operatienc1 and should perfor:: its intended function.

th n- M 4. *.. a

.~ ~

m=..

. i e u. ~.,- w ..e m.

s t #.. e . a uana vvm c.w;:=em, .=a: 1cc e:.cng cnd returning the cyctc~. to cervice have been modified to nininice large cccurulations of water in the etc=line end poccible cubcequent unter hr;.=er.

The inherent prob 1c't in the piping de::13 fnich ellous cuch en occu-rence hr con relatedtothep).cntdesicnengineer for corrective cetion. A pornenent nef 'i-cetion 1:: c::poeted uhich uill help el+.c.te this rator colunn colleccion prx'.r..:.

Fr.ilure > tr Ho previous cinilar feilure he.c occurred et 3rounc Ferry, l

i 1 i

1 l

l l

. _