ML20151L017

Forwards Finalized Task Action Plan for Resolution of Generic Issue 93, Steam Binding of Auxiliary Feedwater Pumps. Progress on Schedule

ML20151L017
Person / Time
Issue date:	06/25/1985
From:	Bernero R Office of Nuclear Reactor Regulation
To:	Knight J, Russell W, Speis T Office of Nuclear Reactor Regulation
Shared Package
ML19284F128	List: ML19284F127 ML20151L017 ML20151L059 ML20151L129 ML20151L221 ML20154E288
References
NUDOCS 8507080092
Download: ML20151L017 (1)

Text

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, b'l i I C O d.

f, UfflTED STATES o

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L i;E:'0RA UJM FOR:

'd. P.cssell, Acting Director, Division of Hur.an Factors Stfety J. P. Knight, Acting Direciar, Division cf Engineerir.g T. Speis, Director, Division cf Safety.Techno1 cry H. Thempson, Director, Division of Licensir.g FF.0M:

Robert M. Bernero, Director, Division of Systems Integration SUEJECT:

GENERIC ISSUE NO. 93, " STEAM BIliDING OF AUXILIARY FEEDWATER FUMFS" - TASK ACTION PLAN (TAC li0. 56191)

,i Enclosed for your information is t'he finalized Task Action Flan (TA?) for res:;1etion of Generic Issue lio. 93, " Steam Binding of the Auxiliary Fee 6:eter Pumps."

The TAP has been revised to incorporate co s ents received frcm the li?.P.

divisions and other liRC offices, and includes an updated status of tasks and revised GII'CS.

Progress on this issue is currently. on schedule.

A r

f A ert M. Bernero, Director Division of Systems Integraticr.

Er.cl e:are :

As StErid ec *./cr.-ic st're :

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!;. F.*isipher i

7. f.m::: 2 L. P.itni D. Cr?.:hfisid T. Chandrcsekaran G. Lii:.ss U. L'.oning

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F. ". :2 r.21-J. i.ermiel

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r.r,e rs

D. Allison

Contact:

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- TASK ACTIO!! PLAf!

STEAM Bl.GItiG OF THE AUXILIARY FEEDWATER FUMPS GENERIC ISSUE H0. 93

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Leti Orgar.t:stier.:'

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Division,.of Systems,Integrzti n (DSI)

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l" Auxiliary Systems Brer.ch (ASB)

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Task lininger:"

' T..Chandrasekaran a. T 121 ' ',.1"' '.

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c-Lead Iapervisor:

Jared S. Wermiel, Section Leader, ASB L

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F.P.."rinci;11 ?s.teuers:

T. Chandrasel: aran,

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Auxiliary Systems Branch

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Division of Systems Integration u

s I.; ::i:;' i'ity:

AllPW?.s(CPorOL)

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i Frt.:t C r;1: tion:

l'ay 1926 (if plant tptcific)

April 1987 (if generic) h k

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7.

Cescristion Of Problem A.

Statement Of Issue l

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Generic Issue 'ho.' 93, " Steam Binding of 'the Auxiliary Feedeater Pumps" 4

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decis with the poter.tial problem of steam binding o'f the Auxiliary Feedwater (AFW) pump (s) in PWRs due to possible backleakage of hot main feedwater (MFW) or steam from the steam conversion system (steam generator and/or MFW system) to the AFW system via remotely-operated "

valves and/or check valves which isolat: the AFW system from the steam,/

convertien system.

This backleakage can occur while the AFW system is idle' and the steam conversion system is operational.'

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The concern expressed in this generic issue is applicable to ali FURS for the following reasons:

w i

h 1.

Even though backleakage must occur through c;1tiple valves in series to cause steam binding of a single AFW pump, once it 6 curs, r

the pctential could exist for com;on ecde failure of the AFU.

system because the AFW pu:rps are generally connected by c:.m.cn

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pi;:f r.g (discharge header and/or recirculatien pipir.g) in m:st p

ft:i r.s 1:ith usutliy a single check vcive te prev nt br.:kisd.!;s g

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to a sec:r.d or third AFl! pump.

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2.

A study cf operating FWRs in this regard did n:t identify eny n

v.plicit ic;ulatcry requirements or uniform pict.t practicas to r3 ;ce tna lihelihood of steam binding of the ATP pa:;s cnd co.:en mode failure of the AFW system.

3.

T:e staar, binding' problem has major safety cignifican:e because

,1) Icss of a single AFW train due to steam binding is presently f

an undetectr.bic failure that ~ jeopardizes the capabiliti of the AFW system to meet the single failure criterion i.e., common mode failure and 2) the unavailability of the AFU system due to stcam binding centributes significantly to the risk of core melt in FWRs.

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/. study of operating history of PWRs during the prior 1981-1923 I

shewedthatthesteambindingoftheAFWpump(s)duetb br.ckler.ht.ges into the AFW systems o: curred in 'a number.of P'r*Rs. '

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Eact:cround p

S:me effort relating to this_ potential problem has already been com-pleted by tha str.ff and industry.

The major efforts in this regard 7

are li:ted below:

L 1.

CSThascob.'pletedaprioritizationevaluationofthispotential

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1 problem.

The evaluation has assigned a high priority for resolu-L tion of this poter.tial probicm.

2.

IE issued cn information notice on January 25,1984, byk.hichcli N3 applicants ind licensees were informed of this potentici pr:biem in the AFh' systems at their facilities.

IE has

[_

t.dfition!.11y prepared Temporary Instruction 251C/~~, hrvey of 1

Lken:ce's Respor.se to Sciccted Stie'ty Issucs (isp 11 %2,192!,),

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which instructs resident inspectors on infonr.stic. to be gathcrad indi:ating hew th:ir respective licenrea hts deslt t;ith the con-U cerns raised by AFW check valve bcchleth:ga and dr.termine hcw they h?ve i..plemented the recommendaticn: in I!!PO SCER C4-3 The re:uits cf this survey were received from lE in June 19L5.

1.

The Institute for 1:uclear Pcwor Operation (II:PO) prcpared a fl'

~,ignificant Operating Experience Report (SCER) S4-3 dated April 17,-

1004 which was given limited distributicn.

Besides lir4fng scme of the events of backleakage into the /JW system that c: curred in 1983, the report included recommendations for improving the pro-i 1

tection against steam' binding of the /JW pumps.

4.

Co=ents on this issue were received by memorandum to R. Ecrnero from J. Snie:ek dated November 2, 1984

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AEG3 prepared a case study report entitled " Steam Sinding of Auxiliary Feedwater Pu;nps" in July 1984.

The report provided l

an "in-depth" backgrcund of this potential problem ar.d also included recom.mendations for reducino the likelihood of steam binding of the AFU humps and the potential for common mode failure i

.cf the AFW system due.to steam binding.

J The AEOD study reported the-following major findings: '

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L a.

Durir.g the period 1981-1983, 22 events of backlerkage into the 'AFl!

F system t.t six operating PWRs. in the US (five Westinghouse designs and one Babcock and Wilcox design) and one foreign F':R (ri.5r0 !;uclea.r l

Froject, Yugoslavia) were reported.

Most of these events resul ed in at least one AFW train being de:lared inoperabis.

Fei. of these cvents affected mere than one AFW train.

Of.tnese reported c.er.:s, i

14 c currid in 1983, indicating an increasing trer.d.of the reported everts over th previcus years.

rt;;rtad events may not accurate.ly refisct either the nur:cr t-i.

'th:

cr ;!r fre:;uency of steam binding cvents or tha number cf.he AF:!*

p r",.s that t.re simultaneously affected in any single plant by M :hlatkage. This is true because currently, backlethy? in o the AF'r tys.1:t. is not by itself a reportable occurrer. e urless it ru.~.ts in ar. e.ar.t which is other.:ise re;crtt.51c by pitnt Te:hnical Specifications.

i Cr. th; !. asis of the reported ever.ts, the AFU sy: tem at l'estir;h:Os2 g

cesi;nad i:P.s appeared more susceptible to backleakages and steam '

" binding of the AFW pumps, presumably because the remetely-cpertted valve which is in series with multiple che:k vcives (the.t isciate the AFl! system from the MFW system) is normally cpen in the i

L'estinghouse designed PWR.

It should, however, be noted that E&W PilP.s (er. cept Davis Besse, Oconee and Arkansas) and one Combustion t,

i eeewp-- at-*W. a e esse op. av es.=e w* w-p e a.4 f

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f Engir.eerir.g (CE)_ P'n'R (Calvert Cliffs) that have normally open or i

partially open (for'Calvert Cliffs) remotely-operated valves in series with multiple check valves (that is,olate the AFW system e

L frcm the steam.cn'icrsion system) have r.ot repcrted events

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in olving backleakEge into the AFW system.

The exception to this,

• is Crystal River, Unit 3, a'B&W plant, where an AFU train was declared inoperable possibly due to steam binding caused by back

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leakage, though the licensee did not identify this as the ressen.

p Also, Rcbinson, Unit 2, a Westinghouse FWR reported quite a few events involving backleakages into the AFW system, even though it n

has norcally closed remotely-operated valves.

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d.

Even though the AFW designs at CE and B&W operating PWRs are very sir.ilar tc the AFU designs at operating 1 5.stinghouse PWRs, steaa L

tir. ding of the AFW pumps due to backleakage has r.ot bten geaerally tir rted at thste plants (except for Crystal P.iver, Unit 3, i cre it f

it, ir.ferred to have oc:urred).

It is r.ot clear uhether the absen:t 4

f repcrte c.e.ts involving br.ckleakagas at these rr.rcion is det d

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.:; ;...it-:picific features.

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2.

.. -e tr';s! cvents involved the ci:op:rati.n or Tailure cf aMut 4

0 che:k valves.

Oparational experience shows that check vaivcs, fit general,'have a history of leakage problems in a vr.ri:ty cf tys t r.: ir.:1udi..; the AFU system where thiy feil op2n er itch c'.

tins.s. A review of the AFW system designs for the thr:2 typcs of

• • lr.3 (.l:.::inghouse, CE and E&W) indicated thet the p tential for f

tre leake;e is scneric to all the AFW designs, because'the check valves isolate the AFW system from the stcim conversion, system in r. cst de:igns.

The analysis of the causes for the reported che:h t

valve Icakage into the AFW system did not identify any pattern er sir.gle rajor cause of the failures of the check valves. The causes g

l dlffered between plants and involved different valve designs and renufacturers.

Furthermore, in most cases, the check valves experienced recurring leakage even after repair and/or replacement.

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f..Ea:kleakage must occur.through multiple valves in. series before steam binding can occur at.any single AFW puEp. 'If bEckleakage L

thrcugh a check valve arises due to improper; seating of the valve, multiple check valves in series may not provide added protection against backleakage.. This is so because the multiple check valves would have to close simultaneously in order to fully *

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seat properly.

Such a situation appears unlikely to occur.

In

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such cases, only one check valve may be effectively p eventing

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backleakage due to the differential pressure available to saat valves in series (reported events involving backleakages into the AFr.' system at Surry, Unit 2 tend to support the above conclusica).

The potential for common mode failure of the AFU syste$ is present g.

st.er.ever one AFW pump is steam bound because the AFW pumps are generally connected by cor=on piping (dischcrge header and/oi-L re:irculaticr. piping)withusuallyasinglecheckvalvetoprevert ha:hitakage into a seccnd or third AFW purrp.

Fcr example, at Arry, Unit 2, schcre all the AFU pumps sh:re a :twor dis:htra p

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' nfer, t, s AFU p mps >:ere simultaneourly steam L::nd in Krie:hr i

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!!!3.

S rrant regulatory requirements do r.ct require i n k'testir.g of any f

y cf the valvss is:lating the AFW rystem from the stcam conversion o ;asuvic:

r/ste, as part of the containc.ent leck rate testin:

testing programs to ensure the isolation fun: tion of these valves.

Fur r.ornsre, existing Technical Specificaticas f:,r cpartting Til.~.s do r. t contain surveillance requirements relating to monitoring a

l or detecting leakage into the AFW system. Also, a study of l

cperating HlRs did not identify any uniform plant practices to l[

redu:e the likelihood of steam binding of the AFW pump (s) and c:=.on mede failure of the AFW system.

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. Tr.e AIOD' report included a sumary of the backleakage events Linto i.

the'AFWs.ystemduringtheperiod 1981-03'.' The sucmary is given h i os. -

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StDNARY OF dACKLEAKAGE EVENTS'(1981-83)

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Con $ents

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Date' No. of Valves Leaking

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'7tioCheckValves

. Turbine-driven AFW pump.

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(TDAFkP)casinghot.

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Pum'p isolated and the train declared ineper-c.

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able.

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2-1/16/83 Two Check Valves TDAFWP casing hot.

Plant in operaticr.a1 lL mode not rce.uiring

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.n'cmps to h. cperable.

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• 2/I.0/52 Or.e Check Valve Train declared incper-

• ?..3/32 able.

Sr.eklet b.;2

,i ct.used AFW flou sensor 9'

t to fail.

l i < 2;. 2 f/11/21 Two Check Valves and Motor-drivch AFlf pump Dr.e Meter Operated (MDAFUP)trippedduring Valve plant startup.

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: 2 i/15/81 Tvio Check Valves and MDAFWP tripped after One Motcr-Operated reactor trip.

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ll 7e AFa' system at Crystal P.iver, a B&W plant, is connected to be.h the

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ta= :r.orttors and the MFW system.

The AFW systems at other ELW

.t treratir.;.:lants are connected only to the steem generators.

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Date I,'o. Of Valves Leaking Co rnents e

cr 2 6/19/51 Unknown IiDARlP tripped on lovt discharge pressure after i

reactor trip.

TDAFh*?

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out of service.

Pump trip believed to be

,f caused by improper dis-charge valve throttle i

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setting. 'Same pump tripped on 5/16/S1 due r

to steam binding.

tr2 4/19/83 Two Check Valves and liDAFh'P tripped after 1

One I:stor ~perated Valve reacter. trip.

Steam vented frcm pump casir.g.

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/.,'12,'E2 Fcur CFech Valves and C:th l'.2.!!D

..a s i. g s h ot.

T : !'. ster-Operated

• Ltahace orth for het

. 4u V.1ve or Three Check utter to t:2 s eccr.d Valve., and One liotor-

r. ump not identified.

l Cp rated Valve Lochage to the seccr.d

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pwp telieved to be i

through cither the c: m on discharge hee h r cr the recirculation j

piping through a. single check valve.

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[:in:en2 7/21/E3 Or.e Check Valve and TDAFUP casing hot.

One I:utor-Operated Steam vented from the Valve casing.

Train i

inoperable.

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!!c. bf Yalves !.eakin[

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I 11/12/53

.Feur Check Valves l'DAFllP.stee:n bour.d.

12/E/E3 Failed to develep flow L

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(11/18/83). Train declared inoperable (12/06/83).

l 2

11/20/33 Eight Check Valves l'.DAFWP and TDAFr.'P

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steam' bound. Trt. ins

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inoperable.

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fcur-Twelve Check I0AFllPt.ndTDAPM f

. a i.v.s c.i d- -

Va*Ves per unit casir.gs het, sor.etics: -

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sir.191taneously.

Pumps run to reduce terpara.

I ture.

I!o pu: p declared inor.ereble b'v it:ense..

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F 7/31 Feur Che:h Valves Gr:ss be.chicaktge fre1 the s tet? g.r.erators li to the APr! pr.ips during hot functiona'i tarting.

1:sterharc.crs c :urred L

5: hen AFllP started (Perps riot required tobeoperable).

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.f r.i.. of six ever.ts are assumed to have occurred at both Farley l

l-ur.its a*.though each train has been affected core than one time since 1923.

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Ho. ~ 0f Yalves. L.ea king " '

Comtents :

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.'.re i E/25/81 Two Check Valves Slow closing of CYs caused't'he AFW" pump -.

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suctionpiping'iobe s

overpressurized

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causing gross back-

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leakage.

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~r.t AE3 study also included the corrective measures undertaken at' the various ft:iiitics i:r.are these back1'eakage events caused steam bindi g of the AFi!

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.::p(s) ar.d consequent incpera'bility of the Ai?/ train (s).

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tepairing ti.d/.or raplacing the involved valves, other corrective r.easures vers also underte. hen at these facilit'ies only. The chief corrective

eras are listed:

ht.

1.

. t TcF.';ca 2, procett al changes invciving.vsnting cf tl.e AFi! pt:ps c::h 1.4f*. u.d deitying closing of the motor cperated va*.ver until check vcive: 'htye had tir.ie to seat properly > ere adopted in Aly 1933.

Ever, rince, no AFU pump trips or backleakages into tt:e system have teen reported.

2.

At Surry 2, precedural changes requiring frequent (during cperator roe.ds) cheshi g cf the AFW system for elevated tc:peratures by using a htr.d held

yr

.eter and leak testing of the valves during refueling outegos v.' ara ad::ted.

2.

Farley 1 & 2 n:,dified the AFW check valves by adding additional 6:eight to tha hichride of the check valve discs to ensure proptr seating of ita cites against the backpressure in the system.

In addition, Farley proposes to install temperature monitoring of the AFW system with annunciators locally j

and in the control room.

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At Crystal River 3, upon receiving erratic indicrtion frem the AFW flow instrument, th,e AFW pump is run to put cool water into the AFW' piping.

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5.

Ad hoc procedures have been adopted in a few operating p16nts..

iI (primarily in those plants which experienced backleakage

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problems)'whichrequiretheoperatortodetectelevatedtempera-tures in the AFW systems.during routine shift rounds by touching the system piping and the AFW pump casings. While this procedure has been'usually effective at the affected' plants, an AFW pump -

at Rcbinson 2 became steam bound even though it was checked once every fcur hours.

As mentioned above, the study recomended periodic leak testing of the AFW system isolation valves as part of the operability require-

. ['-

morns for the rystem, monitoring the system fluid tsmperature, and i

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revising plant precedures to spell out ccrrective actions to Le tshan in case a high temperature conditien is detected in the sy.e t:e..

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ihe prpose of jhis task action plan is to evaluate the adecyacy cf plant I;ecific inform tion obtained in response to IE Tc:.'porary

• s:ruction 151E/C7 in the area of 1) improvir.g the ic11 ability cT tcc i

r.

AFW tystem isoi!. tion valves fcr preventing in-lethage'into the sy:te.v.

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2) pcric<ically monitoring the fluid conditions in the AFW cystem, and l'l

3) tskir.g appropriate corrective actions for relievi.,g steem binding

'I thculd it occur. The need for additionel and/or alternative generic l

cr plant specific requirements will be identified based on the above i

t evaluation..

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Flen For Problem Resolution F

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ircrctch In devaleping generic or plant specific requirements for resolution of this generic issue, the following approach will be tdopted:

1.

The findir.gs and recommendations given in the July 1984 AEOD ctse

,/

study and INFO SOER 84-3 will be utilized as the starting point.

t 2.

Ir. formation gathered frcm the staff review of plant specific informa-i tion gathered from. Temporary Instruction 2515/67 mentioned abcve, and suggestiens and rece;imandations by interested interagency staff such

^

l es resident ir.spectors, ORAS staff, MES staff, etc., and industry

ccups will be utilized in datermining uhother plants have adt;v tely i

t'sait with the concerns raised in this issue.

If it is con:luded that tr.ty have been inadequately considered, then cdditional cnd/or alter-r.ative generic or plant specific requi:tments will be icter.tified.

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... PS:c...ica r

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2 item, "F.blem/ Resolution" and the spccific ttsks described in he er. icstd 5:.';ICS schedule for this gencric issue.

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GENEP.IC ISSUE MA!!AGEMEllT C0fiTR0i.~ SYSTEM ~

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' Tyre Level Office /Div/Br' Manacar T!.C !!o.

53 Safety /

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.NRR/DSI/ASB T. Chandrasekaran 56291 Mich'

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l Ti;;e...................----Steam Binding of Auxiliary Feedwater Pumps v

il:rk Auth:rizt. tion----------Memorandum to R. M. Bernero from H. R. Denton '-

i dated October 19, 1984 u

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n..,................ pr.y,,3n;j ye m3 j a:c;,.n:3 r eetu.:s co ent..; e the 4

it.ter.did fur.ction of the AF,l syrt;.r. inb.w.

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I valves, surveillance prcgrc:.is far conitoring

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the I.Fl! system fluid conditions, tr.d neefed i

corrective actions if surveillance indicates occurrence of backleak=.ge into the AFl! systcc t

will be cetermined.

These d2tc..ninsti na ::111 be based on the 1) firdings, suri, ary cf rep:rted I

52:hleak:.ge event:, and rs:er.er.dttion: given in the AE00 study and IGPO SOER 84-3, 2) staff revieu of the ple.nt specific rc:ponses to IE T :perary 3

Instruction 2515/67and3)suggestionsb.v l

inte, rested interagency staff such as residsnt lt inspectors, ORAB staff, MEB staff, etc., and I

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industry groups.

Specifically, the determination may include the periodicity of preventive mainte-nance leak tests for the AFW system isolation valves if it is concluded that such tests are needed. Also, it will include the periodicity and methodology for monitoring the fluid concition in the AFW system.

The final generic or plant

/

specific determination will involve any cr.e of the following determir.aticas as appropriate for resolving the identified generic concerns in this k

regard:

1)concludingthatthelicensee'sor applicant's proposed procedures are acceptable or E

I

2) proposing additional and/or alternative pro-

f cedures generically or for some plants as Adaitionally, the work scope c.ay necessary.

I include proposing follow-up revisions to pla.it r

Technical Specifications (TS) to impie ar.: pro-i cedures if it is ccr.clud2d t'.It 5.'ch r5.*f:i: i are tiarranted.

?t is erptcted t%: tF.252 pl:rt j

fg specific precedural ch:npes and their irpic.+nta-y tion will reduce the lil:elihood of stet: b i r.di r.g cf the ATW pum-(s) ar.d percible cc:=:n m:di fcilura i-of the AFW s;; ten by e.,:urir.g that the AF;l ry: tem isclation valves perfera thsir interded ic :.ics..

f #e

tr;d Ec:u ents----------Plant TS for cc-rtain Fi:Ps r ty r.eed revisi n to ir.clude 1) pres ntive r.Lir.tcntr.:e te:ts fc: the i

AFW system isolation vaives, 2) surveillance of the AFW system fluid conditions, and 3J identifi-cation of corrective operator actions schen needed.

The need for these TS revisions will be dete:.ined generically or on a case ty case basis.

Standard q=--

~

,o F

14 F

t f-Review Plan -10.4.9 acceptance criteria relating to the AF0 system is considered to be adequate, how-

~

~

l-ever revision to areas of review nay be required.'

5tatus----------------------Some ' staff and industry effort relating to the potential problem of steam binding of the AFW

/

' d pumps has alreadybeen completed.

Previous work on this problem is listed below:

i

~

1.

Based on AEOD's Engineering Evaluation Report

~

f,

~

pertaining to the ste'am binding of an AFW pump

+

!~

on April 19, 1933 at Rcbinson, Unit 2 ILE issued an information notice on Janut.ry 25, 1534.

FWR applicants ar.d licensees stare 4

T-informed through this notice about the poten-l tial for the less of AFU cr.ctbility due to btchleakage er.d consequent steam ferreation in t

the A7W systems at their facilitics.

i sf

=

2.

Signific int Operating E::perience F.2 port (SOEP.)

s E4 's dated April 17, 1904 v : prepared by tha ni Instituto of l'uclear Poster Operation (II:PD) and the report hed limited distribution. This report cr..logued some cf tha btcidec.ht.,e (1.to the AFW system) events that o'ccurred in 1953.

i '

Tha report also included I:M 's retcm c..d i:ns pertaining to procedurcs, training, c:tinte: nance.,

i design, and surveillance measures (c.- improving protection against stecm binding of the Afil l

pumps.

4=

4

p 3

I 15

.v. :.

I 3.

AEOD completed a case study entitled g

~

~

" Steam Binding of the. Auxiliary Feedv: ster Pumps";in July 1984, wherein they presented their findings and recommendations for selvir;g L

,,the identified concerns in this regard.

4.

1&E has issued Temporary Instruction 2515-67 3

relating to this problem in April 19E5.

This /

{

instruction solicits inform.ation from all FilP.

licensees to identify.the actions they have r

taken to deal with the problem cf backleakage p

into the AFW system.

The results cf this fI

• survey were received from IE in June 1935.

I n.

Work on this generic issue vill comence ir.

l,..

accordance with this G'MCS.

~. :V.s.-/?.trolutier.----------Determine the gencric or piant specific m f r.tenir:e measures necessary to prcvide grattar ts:;-tra c

d that the AFU systcr irolatf n valves perf:r.; t' sir; intended function, method of parforming ristcd i

pSriodic surveillance of the AFV systcm fluid lj conditions, and corrective actions required to be taken should surs.ilience irdicate ta:l:lec;:rgt into the A7U syst;m.

Fler.t specific r:sp r.Je tr.d suggestiens from industry grcups.tnd the 17C staff, particularly, the resident inspectors will t:e utilized in this regard.

m

.IP I

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i m

T 16 Determine generic cr plant specific har6 tare modi-fications that may be required to implement the chosen' procedures for preventive maintenance, I

surveillance of the AFW system fluid conditions,'

and corrective acticns when they are neec'ed.

J If hardware modifications are needed, determine i

~

the acceptable interin measures to be adopted for the plant until the modifications are completed.

f Te:hr.ical F.e:olution--------After the above mentioned determinations are I

completed, suggest appropriate revisions to the plant TS as necessary.

L k

• i. r ' I':.

Title /Hilestones Stertinc_/

Cor.oletiqnft'e 1

M:;1r

.5-t of Guidelines Solicit recem Str.rt-l.e;ust :::5 manfatier.3 frca intarcsted interegency Ccspiete-0;t:' ar L-

lif :rch as resiftr.t inspcctorr, 02/.3

'. 5 E 3 4L

.t'.:fl. !;i2 sx;f f, ttc. for resolvinc

'hc ict:. if t:d conccrns in this reg 6rd.

l

~., *:p gridalines based en ite abt've ecc:m endatiens, t'.mnsry of reported hr. chi:anche events 'into the AFW sy: tem, j

...,d;n;r., and rc:cm.rsnditions given in t

t th: '. ECD.StJdy, and recommendatier.: given i

s.. C;e !!:?0 SCE.7 for resolving this g nert:

i issue.

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~~ Title / Milestones Starting /

Com31etien Date

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2

. Evaluation of Plant-Soecific Restonses Start-Hove:ber 1935 Using the guide 11'ne: developed in Task Complete-January 19E,5 -

L No.1, evaluate plant specific infoma-tion obtained from IE Temporary Instruc-

/

tion 2515-57 concerning actions taken by individual licensees relating to preven-

~

tive maintenance measures, surveillance I

progracs for monitoring the AFW system r

fluid conditions, and performance of corrective operator actions when needed.

r i

3 Levelconent of F13nt-Scecific Re uirements Start-February ICES Eased en the plant specific review idanti Ccaplete-April 1926 l

fied in Tash Io. 2, develop additional cnd/

r cr alterr.ativa ;2nsric or plant sp :ific e

1 4

c:dific.: tic: s, t nd revisicr.s to pi:r.t TS a s r.:-:e s s a ry.

Additionally, develcp int ri:. reatures as recessary to be adopttd for tha applicable plants until tha proposed

'::chfits r.re ccepicted.

4 P c:n rr-f.ecult. tory "ecuirementt PacPace Start-May 1980 l

Co.mpicts-April 1957 l

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i Milestones Original Current Actual

ssue assigned to DSI 10/84

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l Pr:ptre Drtft Task Action 1/85-

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Ortft TAP cpproved by CSI 1/85 ~~

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1/22/25 Director i

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Zn:crp:rtte ec=. nts by 3/85 6/85 p

various divisions

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l r.tvi n tr.d reissue a; proved 7/85 F

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Tai: 1 - Cavalopment cf 8/85 t

cui:.;iiries for res..vir.g the

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.:.H*..! cer.cten: r2itti:.;

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.; :: :: ;u.:. i: ::2.

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S :'. 1 - Evaluttien of plant 11/83 tre:ift: infer.mation for.

h gecy cf prc edurts and c :.t { :.".: d e l i r.2 '*;i ~ n tM S t

n.: rn ; sine the geidelinss

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19 a

L Original Current

. Actual Vilestones 0

Tait: 3 - ?tvel pment of Generic 2/S6 or P1:nt 3;3cific Requirc ents...

f Generic or plant specific preven -

l

,tive c.aini.enance ceasures, survel;-

/

12n:e rc ;uitar.tnts and corrective

-t:tions ~ including ces't-affective g

itchfits tr.d TS revisiens when L

ritcde' d2 terr.ined based on evalua-r tier, cf :ltnt specift: infermation I

r.ierred to it. Tesh Ho. 2.

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.Tash 4 - r.agulatcry P.equirements F r.:'.t ;a l,

F y 1.: h :.::{ r. rt et rid:

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pr:;:rs'

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kt;: t ;;..*. c :' by l

i Direct;/, ?!!.

52r.t to

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Package sent to Cirector, NRR 6

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yew g %w ses om._

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Original ~ ^

Current Actual

!'.ile s teres t.

?t:::1;e tent to CRGR 10/86 i

CF.CR revieu 11/86

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EC2 approval.

FR Hotice 11/86 i

.is:Jed for public ccr.ent.

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:'.ii: ctr.:nts in:orperated.

1/87

'c.s Cattr27.Ce 17 nfta.ed.

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11.!) CTJ?. pachtga to 2/87 ea. s... r, l:...

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STEAM EINDIN3 Or AUXILI A8tY FEE 0'.lATER PU'.1PS -

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Ws'oa':t1 Ea:horound This issue was recommended 83.s..for prioritization by DSI af ter a review of the L

j AE03 ergineering evaluation report (AE00/E325)838 on vapor binding of the AFW-pt:ss at H. B. R binson Unit 2.

Further AE00 study of the event resulted 16 l

recomitadations which were docukented in AE00/C404.s 7 1

S37 discusses thirteen occurrences reported in 1983 of steam Linding The report of cat or a. ore AFW pumps resulting from the leakage of heated r,ain feedwattr L

frt: tr.a ;FW system.

The systems are isola.ted by various combinattens cf check valves and control valves.

The back-leakage occurred through several valves in series.

The heated train feedwater, leaking into the AFW system, flashed to

[.

stet.: in the pumps and AFW discharge lines and resulted in steam binding of the H

AF'd ;

.s.

2:trat4.; eroerience to date includes 22 events of reported back-leakage in 5 4

l

.;a-a.in; Fi?.s in the USA an'd at 1 foreign reactor.

In othar cases, back-t iet.e.;e,r'.ts been coserved but was not considered as reportabl6 cc:urrencts.

t I

7tt :::cr.'ai f:r cer.::n mode failure is present whenever one pu p is stetr.-

.:.: Ot: Fuse the pumps are connected to cet. men piping with chly a sin;ie crt-k

. al et ::, preven. t n:k-leakage of hot water to the.seccnd or third pr.p.

5.e t. a t'. & t :' r.:rt than cas peep us.s reported to

cur in 3 o' tre 13 evants Y

~. :a r a.: '..5 53.

' 4 i

bindir.g of the pt:ps was reported on only *f desigt.d plants,*a C..4. s.t o..

s:.-iencege event is br.lieved to have rendered an AFW (*.cw sanur 16.orsrt.':16 l

s. ';r; ::s1 r.iv:.r, e 2:.W-designed plant.

Tha actual e:eret'rg s:stus cf t h l

re;t: train du-ing this evcat remains unknoan.

How ever, the AFW sys t?1 in 1

s'.1 f.l;s is cuffi:iently sir.ilar so as to considor it a centri: 1. rob 1cn for t.11

'.. F s.

h'etv ~'

4fican:e

}

T e 06:P.-1+1ka;e of stetm represents a potential CCF for the /.FU systs: that cc.u'ic <ttit in the. lc.iss of its safety function.

l Pors'h,'e h1etions thtt regular monitoring of the temperature of the AFW jg 410' het ter crendedC37

c. ps :s impie:2nted to provide early detection of back-leakag., cf rrt.in feed-(

Tnts will permit bleeding off the heated water and/or ste m before t

ter.

i teute sitan binding'ef the pumps can occur.

The additien of a pyroreter on the l

AFd cis:harpe line at or near the purnp would permit monitoring of the tcm; era-ture of the fluid in the system by the plant operators dJring their routine 7

t

!I virus) i.:pections.

Records of the temperature readings would show the onset f.

of Itakage at an insidious level.

Trends of temperature rise tires would s1so 1

I ftM P1 0323

_ --. - _3 - 1_ _ _

3. 9..

12/3Di4 y----

pr: vide,f:r the determination of optical reading and recording intervals vnich i

uld ;rr i adequate assurance of system availability.

The use of a pyr: meter vould recute the possibility of error resulting from estimating the tempertture

. tr.e cperator placing his hand close to the auxiliary feedwater pumps or cis:narge lines.

r-12C ITY CITER"INATION 1:Su Oticr.s e

Pe eve.9tr experienced in 1983 are considered typical even though the number of events recorted annually (prior to 1963) are less.

The reporting of back-

'.eakage is enly required in those cases in which the pump has been rendered I

'n:per:ble.

Back-leana;e which may have been detected on the steam bled from l

na system ecfore a pump was rendered inoperable might not be considered a re ortaole c currence.

In fact, it is believed likely that the number of te:k-isska;.e events exceeds the number of events reported in 19S3 and prior years, r: wever, for this snalysis 13 events will bre used as the cnnual occurrence

'esq er:/ Of back-leaktge events.

- t'c eticulaticas, all plants will be assumed to have three auxiliary feed-iater pum:r although seme may have two.

The effect of this assumption will be

..ct t:.:.: tai unavailacility of the auxiliary feedwater system for those plants

..r,ir.; criy two pumos will.be about 50% Icwer than the actual unavailability, t

n er. c.s to the sr.all nutter of plants having only two puT.ps, this err:r is c

..:t.,4 : tad to sigr.ificantly impact trie results.

.r.-

r /:: ' 2 ve,ce Fr tim:te

~

t--

1~ ever.ts ef puts unavailability repertad la 19'5.

E*!ed upt-in

• ? r/; r.n c : :r.: s /F Y, 3 pu ps/ plant, ari 47 p1tr :,

..1 cr cat'.3:li.y/

- - l~; i: c 'cait ed es follous:

i4

& ek

a 1?/(47 x 3 x 15) = 6.1 x 10-*.

il

;..o fcilure c: curring simultaneously was rt:crted to tzic c: carn 1 in 2 :' *'e 22 eventr.

The failure of a second pur; is ti.cn expe:ted to c: cur I tir.c

'r 13 eve.. s, er t.t en cc urrencre rate of 3/13 or 0.;3.

/ s s a.? i r,-

'.h t 9 :u-s h*v'r-it:ome stet 7 bound, the ce n.11tient.1 ;. :::*bility thLt tr.e

.-l

'u. ;,,11

ts r

:cna steen cound is 0.1 re:ults in a c: 4*.c u..:vaii-

iitty of all 3 A~W pam;s of 1.4 x 10 4

e. :r Q' i.',.r'criti:ati:n w.5 barad u,non the Sequoy:h C32*!' study.

1 r.f s

.sissi: c:d t IML tequer.02 which lod to core melt and th2 d:1!n nt contair..qnt f

failurt

1? was due to hydrogcn burning.

It is th. belief of many in the PelA r'.5%, oa'.,:!s field t!.6L ine TML scquence will not le6a to ccie-nvit, and inat t'c ;rt::bility of centair.*ent failure due to hydrogen burning r.ay be re:v:(d g

y crc.rs cf ra.gnitude.

Further, to assume that the Sequcych containment (en

'ce cor:cr.str) can be utilized in generic calculations r.sy not be valid.

l.cn:e, i

1.52 c.:.sca tn:es were rr :..cmined using the results of the Rea: tor Safety 3

Stud / 'a (T:55) and the Sarry containment.

?

.'31/2.'.

3.93 2 N:F.C 2-C E23

L g..*

In the T.35 fer Surry, the Onavailability of the AFW system was calculated to be _1.5 x 10 */ demand which did not include stesm binding of the AFW pur:s.

Tne cajoe sequence affected is the TMLB'. sequence which is increased fros.

I 3 x 10 C/P.Y to 5.8 x 10.s/RY by the addition of steam binding to the A~W usavailadility.. In addition, a very small contribution is made by a TML i

seouence.

+

The FWR release categories are as defined in the RSS.. The whole Lody ren rem a

(:sa is'chtained by using the CRAC code '4 assuming an average population density of 340 persons per square mile (which is the mean for U.S. donestic sites) frcm an exclusion area of a one-half-mile radius about the reactor out i

to a 50 alle radius about the reactor.

A typical midwest plain meteorology is also assu:ed.

Based upon these assumptions, the public-dose resulting fremi each catsgory is as follows:

L 8telease Doce l

Catecery (man-rem) 1 5.4 x IOS e

g 2

4.8 x IOC 3

5.4 x 10' 5

1.0 x los p'

6 1.5 x 10s 7

2.3 x 108 The sten binding of the AFW pu:ps will increase the frequency of the folle, ting listsd s quences in the etteg: ries shown resultin0 in the listed dose.

Frequency Increase Oose Or m ; 3to w ce (R( 1)

(n ;- rt.ng I

1 TMLB' a 2.8 x 10 0 1.5 x 10 1 i

'2 TMLB '-6

1. 9 :: 10 4 9.12

~

eliLB ' y 6.5 x 10 7 3.12 r,

3

'ML-u 5.0 x 10.s 3.0 x 10 1 5

s i'L-p 2.8 x 10 10 3.0 x 10 5 H

6 T!!LB-c 5.6 x 10 7 8.4 x 10 2 7

TML-c 5.6 x 10 0 1.3 x 10 2 C r.sid+rf,; only '.he TML2' r quences the resulting dose is,12.5 racn-rem /P.Y.

The T'*L s>rusm:es a e r> clujed due to the presert un:ertainty reptrding ccre Telt c ' Pi t s o;;t.1:c.

For the 93 PWPs which cet expa:ted to be operating i;svi'g an t..srsge.1:,t cf 20.6 ycers, the total public dose will be 3.2 x 104 can-re.

~

Tae assa ad prcbability of 0.1 for the third pur p f ailing f rom steam binding, given v.3t ts:, has sa failed, may not be conservative, but rather v.ay be overly cptimistic.

If it is assumed that of the thro 3 events, where 2 puaps rcre rep r ed to have beer steam bound, that one event also involved 3 purps, then tae putife cose risk would increase by a failure of 3 to the value of 9.6 x *C4 can-rem.

r _w. ? ' t.w a -

. __.-.__. -. 2. 5.h 3.

_.~._ ___. _..

f.'.h1EG-0913

...s,3 L

Cest Esti.ste j

7, l

• n:'ustrv Cost:

Tr.e cost estimate was based upon a number of engineering assump'.

.icns.nien are celitved to be conservatively biased to,tard the high side of

-'1e costs it.ec1ved.

Equir:.ent costs for the pyrometers are estimated to be

~7,5*;0/ plant ($2,530 each); the selection, installation design, ordering, ins tallatica and test were estimated to be 10 person-weeks / reactor,, or 122,700.

.:o inerstse in operating cost is calculated.

It is believed that the reading.

.d recorcing of the temperature of the.AFW pumps can be included as part of the piant survst11cnce activities which are normally secomplished each operatin, raift.. Test and neintenance costs were estimated to be 1 man-week /RY.

For the 1

47 backfit reactors with an average remaining life of 27 years, the maintenance' costs total 32.9M.

For the 43 forward-fit reactors having a life of 30 years.'

,i the.ainte.a..ce ecsts total 52.9M.

It is further estimated that each pyrometer /

rill 52 re:, laced twice during the plant life at a cost of $32,000/ plant.

The total industry cost to install pyrometers at cr near each pump, based upon the t::cve, is 511.4M.

4 j.

~

1:r_C :s t: "752 GC ccst is estimated to not exceed 1 can'-week /rcactor or $0.2M l

fcr eTiffected plants.

l u.

l L

vthe!* cact Assessrent t

(L

(*.}

F:r the scencrfo in which the probability of the third purp failing steca if

. :::cac it. 0.1, the v:lua/irnpact score is given by:

j; 3, 3.2 x 104 ncn-ren j,

4 11.4 + 0.Z)H

[

ii n 2.8 x 102 ::n rt.n/'!i i

v.

.r s r tr,

, E i-b Ra prcbability ef " u. tM.d pura f allir; n

:,

d

• c * : ^. 2 3, t.E vlie;/i:Otet,r,ccre is given by:

i b

• 9.6 x 134 naa-rom l

i

$(11.4 7 6~i.T ~

1 m.8.4 x 108 tr.t n-ren/$f;.

l

• .,.. Q l

l ilj h?. t%.::..=1 Gr e in :"r.-rem crid the value/leptet secte very frca bortsring lt

!st n,

vien c-hi;h trierity for the third r' p fallere of 0.1, te bich cf the t A r t ;.et; f e ilurr-if the third pump faileras ucre 0.33.

In light of tha u..carttirty e.ssocicted with this issue a HIGH priority is tssigned.

t l

7::~~ W E5

~

l

'"!M *.*C0 (NUREC-75/014), " Reactor Safety Study, An Assessment of 16.

t.:ciesnt Risks in U. S. Co:cerical Huc1 car Pcwor Plants," U.S. Nuclear Ps;ulatory Comission, October 1975.

54.

NUr!3/CR-1659, " Reactor Safety Study Methodology Application Program," U.S.

Nucicar Regulatory Cor. mission,1981.

!I 12/3:/t',

3934 NUREG 0933

[

~. _ _ _

g(

n. v. e a.

c o

_ ( c s' 64.

f;UF.EG/CR-2000, " Guidelines for Nuclear Power Plant Safety Issue Frieriti:ation Information Development," U.S. Nuclear Regulatory i

Cc ?.ission, February 1983.,

635.1:ar.orandum for G. Holahan and W. Minners from R. Mattson, " Disp:sition of AEOD Engineering and Techn,ical Evaluation Reports," April 10, 1924.

536. l'amorandum for R. DeYoung and H. Denton from C.11eltemes,'" Vapor Binding #

of Auxiliary Feedwater Pumps," November 21, 1983.

637. AECD/C404, " Steam Et di'ng of Auxiliary Feedwater Pucps," Office for l

Analysis and Evaluation of Operational Data U.S. Nuclear Regulatory

• Commission July 1984.

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