ML17263A012

From kanterella
Jump to navigation Jump to search
Research Information Letter 0063, Loft Reactor Safety Program Research Results from Nuclear Loss-Of-Coolant Experiments L2-2 and L2-3
ML17263A012
Person / Time
Issue date: 11/01/1979
From: Levine S
Office of Nuclear Regulatory Research
To: Harold Denton
Office of Nuclear Reactor Regulation
References
RIL-063
Download: ML17263A012 (38)
v • d • e


Text

{{#Wiki_filter:.... ~ UNITED STATES NUCLEAR REGULATORY COMMISSION

  • WASHINGToN, o. c~ 20555

.1.. 119 ~ MEMORANDUM FOR:'.).jjar~ld. R. Denton, Director FROM:

SUBJECT:

t:*:::-/ OffiCe of Nuclear Reactor Regulati~n _Saul Levine, Director. *

  • office of Nuclear Regulatory.Re~earch.. ;.. ::..:, * * *-
  • *. RESEARCH INFOR.MATION LETTER - # : 63_'..LOFT REACTOR

~AFETY PRO~RAM R.ESEARCH RE.SUL TS. FROM NUCLEAR LO_SS."'.,. . OF-COOLANT EXPER!j~~~:' ~j:~,* ~D *L2:~.f !~~(/],~:r~:< .. **. ******* r.~ IrRODUCTI~.. * .. **~:~~-i~f~Tuf ~*~s.~~~{*~~~t'1¥§.:~~;;~;**********..... **.*. !*.. *..* ********* '.:. -~**~~;::*~{i~ _;-::~.:. :.':<.This *Research. Information Letter. tr.'ansinits the signi ffoaift rest,11 ts-:_that have". ;~~,t:;;..>:-::T;_~:. ::o:~

  • ..... _.. "-._\\:fr~-~:"b._~-~ri-o~ta.i1ned.ft.om *~be LOF!. :R~~~to}"_,~aJet.y::e-,~~:~earc.h.Pfogr~*m*fr.orn Octob,~r* l ! 1978~;~::~~**>~;_::*:;,*:

.-'}; >:::.'.::<'.. _t,nrough Jun~ l, 1979. :,.Durrng :this time,-. two;,.r,iµcJear 1oss-of-coolant exp~r1m~nts:~"*,*.. *'> * ',*;lI6"-J; ;_ ~::\\:~ ~:::; 1 :r;R:::;~:~:\\;u~~~f :~r1~~:~~~0ITIP 1 ete ~~erati ona 1

  • pressuri zect. * * *.....

_{~::ifL~~'.'.';~*,:,wa~er _reac'.(;Qr (PWR) _designed to.. operate* QV.~r~:t~e rang~ of power densities ~f,: ,:,~;:.,~:::i:?,:';:3:* commerctal PWRs **and. to_ s,tmulate. loss-of~*G.6olan.t acc.idents * (LOCA) ~ The * *.*. :

  • 1
~:;Fr+*>.:*,*~.JOFT s*ys~em and.'* ~ore _confi Q!Jrat_ions a.re* sh9wn *.ln_ Figures l and 2 *.. Jhe. >

,-. _. :=::

  • ._"~_LOFT Res<<;iarch Program (References 2, 3) has.been developed, to provid~ experimental,**:*~.'.. - -

... **. Jnfo_rmatiO,ti relevant to the* licensing criteria for: large comme.rcial PWRs. The . : 'major portion* of this progra111 is. directed at (lo' improved understanding of the *. -~ ~*, -. *i-;-. LOCA and the performar;ice of emergency core cOQ ling sys terns. us i_ng therma 1-hydrauli c, cpre pHysics,* structural and fuel behavior data obtained through - l oss.:.of-coo )ant experiments ( LOCEs).

  • This letter 1s based on data obtained from the.first two nuclear LOCEs

-. conducted inthe LOFT facility *. The two are: part of the L2 experiment series in wbich the effects of. a cqmplett;! offset.shear of a primary coolant

  • pipe a*re stµdied~. L2-? was c;onducted at a maximum linear heat generation
  • rate ()f. 26.4 t.. 2 kW/m* which is* approximately 2/3 the' nominal value of commercial PWRs *. L2.:.3 was conducted at the nominal maximum PWR value of 39.0 + 3.0 kW/m.

J\\ descriptio'ii of :the system configuration and initial *conditions for these experiments :;s contained in Table. I.

~/ _, : H. ). * ~~n~pn *- *-:' ~~-..... - ~-.

  • .:**, *: "::.. ** -~~".'.~*- ~.... _ :,,_.:.... '...
  • ~~~~*fr.'*~;~j~;";L-; **.*.

2:'~'~;:~~-?l((.Ih1$.'JJtt¢r **revlews *the objectives of.. the. LOFT program. and **reports

  • ~-;~:}~~;f;:;,>::;;li~'l<p*~riment~r*cind-analytical results wh~ch.address those objectives.

\\'2;':t}~~~~;*,~~~J'h~. ~xp,~rimerital. results, are.. froin'the two nuclear. powered fu11.-sized .,*:*::;;:-.*J.'"'c~*~*>... ~ou~Je..;_ended cql_d-leg

  • brea~ tests,. L2-2 and L2.. 3~*. Extrapq]at1on l>~tween
  • -r:;::fD;:~::i};~:~~})~$e test~resul~s and.tho:se of the.:zer()-powered Ll.-5:.test provide_the *..

'*-;~ 1.:~~1:~*~<~~2:~<->fe>UQWi!lg conclu$ions and* informati()n whi c.h :CiPPl.Y to the full range of >.. _*. ~~"*::::.:: --~:.*.*.::* -6P.¢.rati_ng powers.. equivalent to ~ maxjmum 1 inear heat generation rate of. -~*-'zero.to.39.4 kW/m (0-12 kW/ft), when there is no loss of offsite power *. *.*-

([~~,i~z~~~~~;~~Q~
i!J ~ y~e~~~~~1:*~~!~:(~}t~o~e ffl ~~~ ~~~1n~~~~~~i~~~1z~ti~ri. ;. ** *

~;:.~'.':i:"~}?'e~~r.s:lJpon.t.he)"~~µ,rn* to po~itiV~ ~Qre. flow; the.. flowJs suffi~ient,_to quench th~ tore ~~~[~~!~t~0~~~;i~~~!!~~~~{~~J;i~l~;~~~J~iiif~~.;~f.~~~~!E.~2 9~.:rov:-.,..

~<t
~j
~~{U:.::.When ~CC from the accumuJatqt\\ begins.. to.. entef "the.co14..:1e9,* 1oca1*tonderis.atiori

' 2.;c}~h~,}:*;;'._\\:;~'.Causes \\a pre~SiJre re.duc~tc>r(_~-~d~*~ ~-* CQnseq'ue.rit~ flow.~'.fro!J] the*. uppef pJenum. :...*

    • i;cs
      *~:~{:;>>/tnto ~he.¢o:re~-... At lower.Jni ttar power~*, th'i~ 'flow,*b.* suffici.ent to ~wench <

if i~~;:~~tf :::::~ 1

. :::::i:::~~::~:r :~c::"::::!~~~~~J~:c::::::*1:::. :::y"PP~r....... *** *

~~1~1¥::.~.::,,,::y:,/ji1ith lni.tlal power to a full.:.p*owe.r -.value qf, 36 perc.~iit~.: Reactor vessel liquid * * *

  • t:,~_it~~;:'t-"~)~?:~:. d:intent rieve*r d~creases *~low* 40 *percen.t of pm xi mum~-.:.-TM s >ts somewhat greater f.!;:s:::.:;c~:":y:;:Jll~n best_~e,:s.timate predictfons *~nd *compares..to* JOQP.ercent depletion *predicted.

~:,~~~;':\\~'" ;,,~* : by<evaluatlon model calcµlations.' Siri¢.e both bypass and.minimum inventory -~- ::>':::* c*.":*:,.affe'ct the time to reflood 'and consequently:* ~hejieak *clad temperature t*~ :*. reached d1.1ring reflood~ these results provide a measure of conservatism

    • . jn best-estimate and evaluation model calculations.

Th,e 1-~~ges:t* hydraulic loads a.ss*ociated with a. large break occ~r in a *.. . plant fnitially_ at hot standby; and decrease with increasing power. *

    • Jhe ma'jodty _of the hydraulic J9ading energy content is in the frequency
    • *. ra_ngl;!.below 40 Hz.,, StrtJct.~rar design methods, similar to those used for.
    • :'... commercial PWRs*~ are _shown tQ have a large margin of safety..
    • .<: Al.1 four Q.f the best-_estimate codes used to predict L2-3 predicted generally
  • ,*higher cladding temperatifres_ than those measured. **
  • . *-. l.

. :,_Jhe. absence of a significant quench in the Semiscale counterpart tests

    • is bei_ng assessed.

e****

  • H *. R. Denton

... ~.: *... ~

  • - _.Improv~ents:'*_;n* RELAP4/MOD~i. input parameters and syste~: iOOdei's "tiav~ led

,_ '....,:,:.to predi.c;tiq,n~.of system hydraulics *and. cladding.temperature r,esponse:

  • . _;_which.agre~rwell with L2-2 an.d L2-3Jnea~urements. *: When applied to a ** *....
  • * :'*cormierc1al PWR~ t~is,improved :~ode predi~cts very similar thermal-hydraulic
  • . respO'rises *. ~ sc"al i.ng di_fferenc~s.*between LOFT )ind the commercial pl ant, * *

-.. *:*, suC;.h as core.flow~*core length, *and steam gerieratOr configuration,.are

  • shown to have no sig*nif~carit effect on. the conclusions reached.

.... ~*.. *.. As. ~- re~ult of the 11µclear ex.periro.fint. results obtained thus Jar and.*.

~s a result of the recent TML.accid,ent,' a new test *sequence is being
  • *:.: *** *" ** fe>tmulated._.which advances several small b'reak" and transient tests to. *

... begi_n.this year, and postpones :ttief,remafnirig.. :tes.ts.irl.thi()arge. break

  • -~:"'*-~;:... :.,-_: __..,'_series. unt_i1.*1ate 1980. and 1981.. >Information from sma.U. break and.-
    ~-.?<<~~~*--,_:;'.~~-_transient tests will be sent to you via.Res*earch Informatfon Letters

~.. *. - -... '. -*~.,.... . *:*\\. 0

  • T,he. specific*LOFT program objectives are:

~:_*-=~;**-.-:-:-..:...... 1~~5;r~-. **.*... l.*,.* *:::~H:~~t~~~!:m~:I=~~~;~~!~;!~~~ ~~~:cl~*~~t f~~~~s:ic;;.* !+/-:~;>~i{'.}~7~~;;:-:/.;~:'

a. The :transient thermal-hydraulic-, mechanical, :and nuclear response

.tI;)~~<~* '~<-::c:

  • ~-- ~~dt~~o~:~~~~r t~~~;~~n~n~0

-~~~~~~s ~ystem components under LOCA

b.

The capability of curr~ntE,merg.ency Core Cooling System (ECCsL. . *designs to fulfill their* intended function. -~

_-.,~

.. c *. The margin of ccinservatism inherent in the capability of current.. ECCS designs.

d.

The effectiveness of alternate ECCS concepts *.. .2. :. Investigate thresholds or unexpected phenomena that. could affect the

  • .*
  • validity of th~ ana1.Ytica1 models *used.to predict the thermal-hydraulic,
  • .**.mechanical, and nuclear response of the reactor system. *
.:.--:':"°':--

. "' ' -. **. ~ ~...

i _.

  • e I
  • H*. J~. Denton

... 4 -.... . ~...The.first LOFT. experiment series, designated thell series, was'. nonnuclear tn :~ .>:~,*~'.~'*:~:* **.. <nl* a 0 .. tu re a.nd s~r(.vbe)cl to.{ad) deval uaf:te and1 ver.~fy thed. dstruc1 tural. intfegri1ty ~f. t1 he **. . :., FT system; . *

  • prov1 ~-. ata or_ eva uat1on an. eve opment Q. ana yt1ca

.. :'modelS'us~d.to predic:tthe'hydraulics in response to*)arge pipebreaks; and. (c)_' provide operational experience.t:or.the simulation of large pipe_ breaks.in ... PWR systems at powered conditions *.. Several nuclear test series have been ~->.:: defined, one of which.is the t2* s~ries, wh.iCh is intended to provide -~ <.. -... :... *'".- integral systell_l exper.-:iti1~ntal. dQta *related to the full size.doubl e-'ended *.**.* * -~~** ;/> :.~ ::c*old:.:.leg.break_.at ascend}rig po~er leyel s and with cold-l_eg -ECC. fojectiori.* .This letter is based bn _lh!¥ results of two of the L2 **series *experiments, '.L2-.2 and L2-3, whi ch __ ~~re the first ful Ty integrated. PW_R systems. lo_ss-pf- .. -" coo 1. ant experiments.* to. *be conducted in the world. "~. '_:_ :-..-=- ;; **

  • :::' *. (.~-

.~*_... :.*_:... *.-:;:~:.~~-:~-~~---___ ~~:~~--- ! *:...... --* ;.

,.~:-~ **

-~'

~.:...

c'i~~t~£~~;~~¥-,~~~lin!l ->...

  • -:.:::*:,..::*:;;*t:-~-

scal irig *rules applied in LOFT. are as fo_l lows: * ~ * *,..,,.... "_,,...,,;,:;::;;,,

_-~_::.:~.---~~-~~-- ',-

.: _*-. -~.. *.*~-. *.Fu.el llnea/h~a{.generation rate* is iull seal e.

  • The tiucl e~r
  • fuer*~ >,

~~i~~-:~:*~~:..,.-.,. --;>,...,

  • .* qesign_has.thesamel5.X 15 geonietry.ascommerc.i_al reactor fuel.*::

<:::~* . p.i fference's(from the commercial fuel are length ( l. 68m),.* . :*~;* *::.:._.,: *.. *..... 1 owet. fue 1 clehslty. and. fuel. pins. not prepressuri z_ed. (an experiment. ~:-*.~:i;:: *>::.'..using prepressutized _fuel is planned)~ *. -*~ *-* *. When feasible, core power is taken.as the basis for scaling of component volumes; that is, LOFT Volume = LOFT Power x PWR Vo 1 ume i" PWR Power. -. ::.. ~::..

  • Flow areas are scaled to provide similar mass fluxes.

The ratio o.f. bre.ak area :to system volume is set identical to. the

  • commercial PWR value unqer study. Hence, the primary coolant system percentage water* inventories vary in the same way with time.

Initial co.nditions (pressure, temperature, mass flux/core power) are set identical to the commercial PWR values.

    • LOFT is actually one of thre.e systems that *are related by this scaling rationale. The Semi scale faci1 ity (Refer~nce 6) is a scale model of LOFT usJng about the same scal:e ratios as were used. in sealing LOFT to the commercial PWR.. The**major scaling parameters for LOFT, Semiscale, and the conmercial PWR are sul1illariied in Table II.

~ -

  • .,.~.
  • -~
  • . ~ H~. _ R. oerlto*n. *..

~. .. ~.:. 5,;, .** )b:e.design and ope.ration of the.l.OFT. facility ensure that all* the significant .*: :. pherioplena _,oc¢ur; in apprqxin)atelythe s.aine magnitude.?.nd time seqlJence *as would

  • * -~ :: ' '
  • occur *. in* a. c::o11111erci a 1 PWR LOGA/.

A~ses'sment o.f the s:ca ling rationale is *. -*~ : ac*c::omplished by: (a) compari,son *of LOfT experimental results with tesul ts of -~j-_co*~n'!Jl:!rpart.:experinients*conduct.ecl in the _SemiscaJe* facility,*and (b) applying the s)im~* modeling ~~chniques to.LOFT and the eomrnerdal PWRs, with LOFT LOCE initial. .,*: c:ondlt,~ns;:/a1.1d eya_luating the comparisons~ :. *

    • ~*..

. -.;* ~-*.......... 1

1~.~~*
fo*:~*?~~}~ Pi:og ram Ac~.i V,i ties

~::;*;.:::~;.:::>:,..:.)he. l..OFT.Program consists of* bot_h experimental *and analytical phcises ~. The

iDf:i~:~].*;~~)'.'.:~~::exjierimerital
  • phase_):onsists.of t_~e phnnfog_, preparation,:arid ~onduct of the..

. _ ccifl~ufrent with tne* experiOJerital-'.program,- *supporting analysis provides._---*~_.-"'"'.. ::?::.~-~-~.,~:-.-.';.;~;'-* . ;* pree~p~rJm~n-~~r _pre~ist:~on;_and-* :~ost.;¢XP~t1m~nt~r~_an~lysi ~.-_.f()_r.. the *pu~p?se *. --"<:,}.'<':*;.;:\\::;~"':;:~~: .:*:" *of_deyelop1ng <<md ref1n*rng cQde. models an(f. Hlent1fyrng areas for add1t1onal -~:: <:-.. >;

  • .. code, developinentt_*:~ Th¢rmal-hydr~ulfc*J1naly!)i s of L2-2 and L2-3 was..

.. car.ri.ed oi:rJ;' pr,inCipally *with the RElAP4/M006 (Reference 12) arid FRAPT4

fReferenc;e 13)"- codes by EG&G Idaho,an*d-with the TRAC-Pl (Reference 14) and*..

' TRAC,;,,PlA (Reference 15) codes by Los Alamos.'"'> ~ ~-; . ~~----.-. -**;o

,.* 3. 4 ** LOF{ Oata. Uncertainties

,.. *... -. * -Iri general, the uncertainties in the principal measured variables are.as -.'~-~*.*:::

  • ** fol lows:

. temperature.

  • pressure*
  • differential pressure density momentum flux

. velocity . +3 K +0.03 MPa +0.-01 MPa * +0.03 Mg/m

  • +12.0 Mg/m.s

+2.7 m/s 1.0% . 2.2% 0.2% 3.75% 20.0% 13.5% .. Techniques*(lnd instruments are well developed for m~asurements of the first

  • fourvariables; consequently, these measurements* are relatively accurate.
  • . * ** l:fowever, '*the fuel cl adding.*temperature measuremen.ts can be up to 30 K low during transie'nt conditions. d4e* to hydraul 1¢ influences on the cl adding *

':. * *

  • external* thermocouple.
  • Th:e last two variables, momentum flux and velocity,

'are diffic~lt to *measure in *two-phase flow condi tion*s. *.The uncertainties. ' *:stated for* these. variables reflect thls difficulty and represent the 1 argest 'l..n'lcertainties whi¢h occur ~uring lci'w quality fluid conditions. Full-scale .flow calibration work, now in progress9 is expected to reduce these uncertainties.

-***e . ~ H. R.- Denton ~* - 6. -. 4*~()... RESULTS'.* ':...... 0 *::'*?<, *'./ "The 'resu.lt's obtained from '12.:.2. and ~L2~3-represent a significant

  • .-~~~<*,_: ;:, "'. c 'a¢hlev,ement Jh the *NR'C 1 s react()r.*sa:fety program.
  • _After many years of

_*.,\\'.;*;...>.. :-_PT~onfng, _construction~ *a,n~*:experimerita:tion, the first *experiments have been_ :* * ** .:_;;?~E~*{ ;:y(* *.. ¢cfo1pl e:te.4.,Y.ffler_ei n_.t.oe. :Jnte9rated.*effects from a, loss-:of.._.coo 1 ant accident.. *.. *.* <=i:fk'..::;~_::;~:~~:' Jn a.J,llllY.,;,OPE!rationat P.WR have: been *evaluated.,, The experimental data obtained

.:::i:tfEl.:*-* :~r >from t~:¢se Ji rst two* experi~nts ha'Ve many important impl ii.:;~tfons on the early

~:::~s;;~t'.~::\\:.* :_*.*:tt1H*i,r19 (Reference l6):'; :.whi ~h. formect the. bas is of "the 1 i censJng criteria in. effect"

_
l~>~>-.*<
*: _:today *.. The dat_a also have _implica-~ions on the expectations of thermal-hydraulic *
  • '.?l): ' :_. phenome"na in comitiercia 1 systems.. *: subjected to 'similar loss-*()f-cool ant accidents

,:*::~~0~~~/:,~~'i-i:/*:"aod'.O'n the s*afety margins* qes{ghed into the systems Jnaccorda*nc;e with the \\*~~1-~~};~~sfi~!~g:i~!.~~t~r~t;~~~~~~<l!~~:*;~~x~tC~7.~(~:~:;:~c!~4)~n~~~*~;i.~~e~,!~~1~:.r~~:~a-' *

  • "-~:~:;_;;~'.: *:. *.. --*-~t:1ond range of corril)er~1aJ,PWRs fr,ollt.hat standby conditions with the. reactor shut -

~~:;~;~~:. \\d,:0~11... -to _.n9~J~a1 fu1r'p_ow~r op~t7atjng c9n~i~tons. (v. i'.z.' maxfmum linear hea~ ..,..*~:~--.::.;:,~'lf-:-.z:..

  • gene_ratron: rate of.~9. 4 kW/m').-; * *Al 1 of~ the experimental data thus far*. obtained *

~~;~~::.;_J,s: indiCative of the"effe¢ts*c.*resuJting: froefJhe Ja_rgest possible pipe break ~

. _... }
,~i-52-:::E~~h'e qo,uble>ended offset.st;ear:'.of.. ~ *prfma*ry*coolant cold-leg pipe~ The results

~-,~~i~ri;Ji;g;:r;}~l.,}:2:?;'an.d L2-~,.an(l~f" th¢'rion:ry~~Je~r~-_t~st; *tl.~?**-*are pr:*s~nted". in the:,._**., ~;:*+?f.:j;';*~~;-tf(*:$J.l~Ceech ng **se.ct1ons ** ~ 1 ong with :the1r. :rel evancg. to t~e seal rng rat, ona 1 ~, ~~~ID'~;'~s?~'f:~!~f ~~~~~m~~~R1 t~;~~h~~~~~~l ~~ arid ijspects be 1 ieved to be;

  • f.:J:f~J3:~~~.. ::_:-~-~4-~:,~~\\JOFT LQCE Thermal-Hydra,ul ics

.' ;" _:_,~*_:. * *** ~1~/.~~;*:J/..,t;;;,;:::.:L1ij~~:i11~~~1~N'~raulic t"ran_si'~n~s in e~p~rime~t-~ L~-2 -a~d L2~3 are.-~-* --~:/' ~:' '....... ~;::"~~Li~:~>*l~,:;.;~:quB:f!titativ~lY:jiescribed by _the sequence of.events given *tn Table IIF >-: _ "*.

    • ~:c~;t':>(<~,(**and by the_sµmmary *of phenomena resalt-s giveri fo Table. IV.: The information..... ::
-'~'.im;.
;-('~:,<.: in* T~ble HI and *1v ;' along with the, initial C()ndi~ions def foeµ Jn Table 1,-:::

0

~~=::;',~:{<. ?i.. >pr.Qvfdes a clear description of the. loss*::.o.f"".coolant-phenomena resulting.. **

_ *. front a double ended offset shear in the cold leg of a PWR priinary coolant - .* :~ .. :};,,::'. '* : piping loop.

      • :. ~-

. < ~Th*e*chr.onolpgy of events shows very similar behavior between the two ,. ~**,; )~.,~"_,:,,.-*n~clear experi'ments and also.very simi'lar behavior between nuclear and 1~/:r-:nonnuclear experiments for those ~v~rits not 'Strictly.associated with core

  • _:,;;~'-~.'.:~.:~":tpower.** All q()nclusions fr.om the nonnuclear series and reported in RIL #37
    • <*:+.\\.. (Reference 4) were verified in the 12-2 and L2-3 tests. * *

/: :; Th~{~essation of :fuel cladding temperature rise and subsequent core-wide ,,,, :..:return-'t>f fuel cla~di-ng temperature to fluid satu.ration t.emperature within. the first lO*seconds of the transients were the dominant events that influenced the

  • *;;' simHa
    r ~equence characterHtits which occL1rre<:t subsequent to the first 1 o seconds

.in both 'the nuclear and nonnuclear experiments.*. These thermal phenomena are the, ** .-- "'result of primary coolant system hydraulic phenomena that are dominant and which'..

  • control' and limit the fuel cladding maximum temperature to well below damage_. _

thresholds *. As the chronology shows, the cladding returns to fluid saturation,

  • ~.-*.

I . :*-~*....... ""

~

'-c::::..;.,.: _:*'.*, -~****-**:*.:_::-.c::**** _H; R. *oenton * - - *7 - -_. -;... : *.-~... ~,,......... ---.. ~- *:.; -*. . ~-**.. ._* :* :*.-. P-efore actuation of. a~y::*~rf the ECC sys-tem~*::ci~ *b~th 12~?~-~i\\((Li~3*~:-:'.' Ih:if. :*. - 'clem,~nstrates t_hat for.the* ca.~.e of,no *1oss of offsite pow~.r the ~ydraufi_c'. __ phenortienon that_ causes the* core~widEf return of cladding temperature tc.> fluid -~~aturaticm temperature is *suffit;:ientlY. dominant to overcome the thermal. driving force for maximum linear heat generation rates up to the nominal

  • * ' ~-~R va 1 ue* gf. 3~-* 4 kW/m.
  • _Tbe hyd.raujJc limitation of the. f~el cl.adding_thermal respon~~ was cau.sed by

.***. "C:::.:t..hereestablishment of a positive core* flow of high den_sity*fl.ui_d during_ the -.. *-* period from about 2-. 5 to 6 secori~s after.*breaf io.itiation (Reference l i, 18). Th~ *resumption of positive cote flqw occurre~ once.. the lower. plenum fluid reached ~: sa,turation, effectively.decoupling the bro'~eri, lopp'.'co1 d l_eg ~.and' Ct>:re Jnl et.*.* . ),~;J.::. **.. :* . mas$ flows~'~: Since the primary.c*ool1'.nt pumps. h'ad not ye:t -~tegracltad~_sfgrjificantly,. ~~l7~~tii~;:!:~~i~tJ;f g~~!Uf ige!fu~~]:ij~~li;~~;:ti¥m;~¥tw~;i!Ef~;~!j~i~i~ 1z.':':.**.f::::-:".-: :~~~':. flow *.at. th1s time $U.cb that the.. roass eJected :wa~ Jess than that supplied *.,,::;:*;""'.:;-'"::.:=',;-o'~:."'*;'.. ::*~"""-"'-"': i;:;,?-Yt:':\\f1::;:~'" to the downcomer. from "the-pri*mary coolant*_:pumps<; Ttils. condition_*: -~,;~*~-.. : :.,:~~"'.:.:,:.;*.,::=-::;;:'** _: *:::_:\\T.'~~:~2~fr 1::-\\c;t;:: *J:-;:.. of excess coolant flow. into the downstream siae* or *the :core lasted until* *

  • _ * : **<" /;:;~<'t;!;.~

'.. ;i :::=:;:*.. :~about'6 seconds as shOwrj in Table*: iv... *_ CQriseiu.1¢'ntli{during th.is period,' the

  • .:_{'::::*:~:El:{~.

'.:*~--.7-: ::.*~re*established positi.ve. core. flow 'prov1dad-.:~specially. good: heat transfer. from

  • .*the.core and a core.:.wide return of fue1 *cladding temperature_. to. fluid
'*-~~:

s t t* t t 2. aura1on emperaure *. - .~..., ~-

-=-~:-'*-

.. *.. ~ ~ -**~--- i* .. *--~~::::-\\*~~-E;~-~1:~ar.1*y~ to* predict the co~ciitions *de~_cri.b~d ati6~~~,- a.. ~~de_ m~st pertnit*:asYi'.nmE!trie. __,. *; :*-~:

    • .,:*::::;:_:):~~:{:: downcomer flows.,:*. In additior:i. nod~liZation_.10 lumped'"paramc;iter modelS becomes:;<~::.:.,..

-.:*~::::'*:-~~:;; ___,_~impprtant tn the handling of.the propagation of density and temperature waves*,.._*_*.._.*--~ . -~.:-* --'::*_. in',the downcomer.. A!nplitud,e reduction through mixing in the modeled volumes_ _... ~.. -..:~.-- **can result *;n-underpredicting the *amplitudes of thermal-hydraulic phenomena.:-- :., _- * .. --. ----*.---.Split downcomer models and nodal optimization studies can be made using -~....

-,~.::**'.. :.
  • L2-? and L2-3 results as references in order to minimizc;i_this deficiency.

'~. '

  • ,The influen~e of the prima..ry. c;oolant system hydraulics *an. the *fuel cladding
the".'.mal response js shown in* three-dimensional Figures 3 and 4.

During the . first 10 seconds t.he hydraulic behavior just described resulted in a significant _rel)10Val of the store.d energy in the fuel: 65 *perc~nt in the L2-2 case and 64

*
  • petcent *in the L2_.3 case. After* JO seconds the remaining stored energy was.
  • .sufficiently small that_ subseq.uent clad temper~tlires did not rise as high as*

the initial values, and the. c*9urse of both experiments proceeded without

  • significant.differences in the* phenomena and chronology of events.

2

    • .*. A modif1e> )nd uridam.~ged_ after two. nuclear~ LQCEs.{Reference 20) ~:-~-Al so,. wat.~r chemistry samples.

-~.:: haV~ ~hQ\\'iO flO. fuel dartl(lge or lea~age pf:,fission products.;: furthermore~ lead ~>.:{': 0

rod t~sts (lLR 1 to 4 ari*d loss,;,.of.;;;coola.nt*test, LOC.. 11) done.in the P.ower
  • ?~::L~=~->.~:.*.: Burst Facility demonstra.te tha'.t th¢ degree of damage to the fuel': is not too

.*.:~~;.;;,, *:::-::::.;'-* severe to prevent re_use,._even in tbe event the rue,. \\'{as prepressuri zed... -~>~:~~>.:~~:j'::***-~~~ur~s 3 and 4 al~o.sho~ t~~t al~ dad~ing.temper~tur~-~- i~ -~h~ L2,-2 c~*s.e,.*:... ~...... *., \\

  • and the upper 1eve1
  • cl a_dd frig temperatures. in the L2-3 case, quench* once i}i?>:-::' ::*::~;~>again at aoout*;.18.. Se!=Ond.s,... Very shortly afte~.. the aCC~rTIIJlator,;Jnjection *began.:.*.. _**.. ***'*:*:c

-~... *::.~; ~ -:.... ~'.~s.. ~rZ!::~t~2'Y*:, nonnuclear --experiments~ The ECC ~ypas~, increased: slightly with, ncreasrng core ~?fi*~f:'::>~..'**power density. At t.h.e*'~nd of acc~m1.1latq,r.flow. in tne *ntmnuclear experiment ** *. *

  • ~'~:~:::_:.;* *: u.. :511

~he.Ecc-bypass:*w~~- 3o*percent of the total ~cc-injected.up to that time *. <<"=> . T~e ~cc bypass inC:reas.ed to 32 percent in L2;..2 (initial power 26.4 kW/m) and. * -36 percent (initial power _39.0 kW/m) in L2-3. 4 ., *.** ECCS in cord unction.\\;lith the. tlydraul ic phenomena. iri.the pr.imary *'coolant system ***

:preve)'.lte9 c:-omplete depletion.of fluid. mass in the reactor vessel during the

..*.transients\\* Ca ltulati.ons of mass inventory in the reactor Vessel as a function ". -~-"**' 'of time showed tMt r~actor vessel fluid mass does not deplete to... less than approximately 40 percent of ma>.<imum at.any tittiEL.... The lower plenum mass inventory_ ~*****was nOt._fu*1.*1y,depl~.i~d at: any tttri~ du~i*li~J. -~he* L2-2.:-and* l-2-3 *~ransientso. B_est

  • 'estimate *calculations (Jsil'lg the RELAP4/MOD6 co~e also show incomplete.

". depletion of lower plenum fJuid, but ma.re depletion than the.* experimental data as shown in Figure 6~ Applicatfon of Appendix K evaluation model criteria to these test conditions results in c~l culations of complete depletion of the.

  • lower plenum fluid.**. Thus; AppendiX K is demonstrated to be conservative in the calculation of lower plenum refill and start of core ref1_9od.

3 .Movies are available from -the.coordination contact for this RIL which show the progression of the quench fronts through the* core as described. ...

  • 4These bypass* figures* are based on.the results o*f the no.nnuclearseries, *which. *

.. '*was specially designed to evalu.ate bypass-(:Reference 21)~.inodified in accordance

  • with.broken-loop flow measurements *and other ex*perimental_ df fferences.

An independent measurement of ECC bypass by Kehler (Reference 22) supports the .* ECC bypass calculations.

..... :J*....

=.** i:!~t... ~... *=~.. *:.
        • ~'.~~~.:\\:

-. "*:>_:~;?~!'.:~:\\. <:.. ~::.-*. ~.. ~<~*'..' *,-.....

  • ~**
.~c.. -:.:r.~:,.. :**..

---~

  • ~ *:...

.;.~.. ..:~.~- :** . _. The core r~flood rate was _essentially the saine in all experiments p'.rincipal ly*

  • .* : -~.- _b,ecaus13.of tile s_ig.ni ficant ~em(>val of stored *ene.rgy from the fuel early in.-..

_ * ;.the transient." However~ quen¢hi:ng of the fue} cladding in the high powered * -:..- region of the core *was delayed with increasing tnitial power," as shown in Figure _7. 5

  • _-: 4.1.3 Jhe Effects of Cladding Surface-Mounted Thermocouples_ ot'l the Results

/ ~... -,,,~~-<::- _ :-* *. Mariy investigators, including _i group of 44 specially convened experts* (Reference. 23)

  • ;_i:*'.~1~:*:}7'.~"5;:*~.h~ve studi~d the poss i_bi li ty t:hat ~he. pres enc¢_ of. thlf cl ad~i,ig surf~ice.:.maunted, ::. *. --

.:c.~:-_; __ ~;;,

.>:< thermocouples influenced the early cladding quench observed.*_ While. the*majority*--* *-** * *
    • -~~;..
  • agree~ that. the perttnent ~ata (Reference 2_4) support :the.. coticlusi on that there

'.. :was no significant lnfluence, it is felt that.-current.:experimental wC>rk described:.-

4\\~-;\\;W;
,* ~--*~:: ~ b,~ l~w wi n_ -~;~e~ -~r: -~/~-~~~ *:j_~'.X~~J ~;~ir~~~:~~~~0-~~~~i_-_-:9~j~~:\\~~~~-:1~: :~ -_ *' > -** _::*. :. \\..

/:~:;.::~~~:-:::: ':::;;'~:,.Reg~rdJ.rig. th~. acc(iracY._of the-* cJaddi_rig t¢mp_~r~t4.r:t:!.)~ea-~ur~!ilf:!nt by these ;* :*_ ,:~t~f~~;;.::;~f)~Lthgfylc>'c()u~J~S~ :exp~rim,ents_).h Jhe.,LQFr;_.~~s~'."~~*ppo_~~Ja,.~i.l1~~ _ (~ TSf h the.Po\\fier.:~.-,,*=**_-........ '.~j£::~:&;frt:*::: Burst F~clll_~Y~.the he~t _tr~ns.fer f~c1lltY at.:C.ol_ymb1~)Jn1vers1ty; and the*,

  • ...... _"',,;.,,**r.*,.,-;,
~r;::;?~s/r::~~L:,.German* B;aEKA-f~cilftY: h~ve* 1~d. to* the '_conclusioif:-th~f".th~ _thermocouples:_ **
gi[
f~~:;;;:,*:;-,::;:F:'_:de> *not* signifi_cantly_ pertur~ *th~ cladding s.urf~.c:~r:tempera~ure~ - The*. LTSF:.: *. _... _
~f~~"!~i~i:\\~f.'{:;0~" :~te~~1~*~~ lp_di.cate --~~at)he ext.~rnal.- thermoc~_~pJ.~s_.agr~.~ :wtth.,_ imbedded * --- :: : * *
~*
;,i7h:'~~~1~S~/ thermocouples to. w1 th1 n 30
  • K~ : Independently ;.*"analys 1 s w1_th. the. FRAP-T4,..... :

g;f~4-:;f'~cf"~~~::<arid*:'.other--code_s. has shownj '.through fuel :rod,_stOred energy correlations,:.. :..,-- -<.:._ '~1~~~~;f;~x:;;,'~*~~~~?'~Jha*t the LOFT-external thermocaup le *measur~ments" are' not"' si gni fi. cantly perturbed - * 'i1~;;;~~fr~~:i1:;;~~~~'Lf:>Y the therm,ocouple fin ~ff_ect-o : Furth~r experimentation iri.. this* *area is being ~~5~~";,2.;~~-:dt}::':P~rri_ed otit _*in_ these._ a_nd *other -faci l ith~s t9.- corrobor~te these.conclusions,*_. f=::;i,:YF,~~- :*:.. :'-~c define thetr l imitations, and "better quantify measurement.uncertainties.*

  • ,:_*/ **~:-:::..... '.

-'.:::'._,. :.:* 4.1.4.. Hydraulic Loads During-S~bc~~led :Slowdown The three experiments,, Ll-5, l2-2 and ~2"'.'3 cover the range of core 6T. ';.,~ ::.* <- ** *values whjch:oc_ct.ir in:PWRs -{O-, 22 *.1 and *32.3 K, respectively). Hence- .. :---* _.these experi,tnen:ts provide information fo'r determining the pressure transient. *

  • .. * *. typic_al pf that in ~WR's that. re$ul t from.the largest pipe break for initial

~-

  • .
  • conditions varying from hot ~tandby to nominal operation. The system. ** * ** __ >-.

~ .., -* pressure data are shown in Figure 8 and the chronology. of events in Table III.

  • subcooled blowdown la_sts lon.gest (0.10 seconds) for the hot standby condition test,
  • ** - ll-5. *This is because the conditions provide for the_ la_rgest difference

' between initia*l and s~turatia*n p*ressure *. However, the subcool ed blowdown ** time also depends on the sonfc velocity which decreases as the temperature increases. Thus~ as observed in Figure 8,.as the temperature increases ~._.in the~'upp'er plenum (ln~- hot *leg, the rate Of depteS$Urization*decreases..

  • S.i_nce hydraulic loading of reactor components is reduced both by the reduction

'ln d~pressurization rate and by *the reduced subcooling, the subcooled blowdoWn loads are less severe as the core t:iT increases. 5 For example, Figure 7 shows that in L2-3 the central fuel assembly, module,5; did not quench* until about 10 seconds after.the flooding level passed.

1*'* ,~ --~ -~~...... __.:_ ~* ~---**.,,.. ~~ -~

  • ' **:~.- *:' *.,

-~-~--. *.. l"*... *. <* * *** : '-~ '*-:, __ The :_data out to o.*2 se.conds were taken at a b~*ndwi*d~h of 1000. Hz to ~n~u:*re ~~~sureC*:; **<-- _ .. *: --:*ment of all signifitant _frequencies. Analysis of the subcooled blowdown pressu*re _:----- =-~ _* -

..,. data reveals negligible energy, content at 'frequ_encies*:above 40 Hz." Furthennore, _- -.........

_,. *.th~-:.data indiCat'e that at _high*. ~inperature and press1.i'res where water densi tYJs. : -.... *:.

  • :-.: *::::; only 2/3 the maximum *1ower-teniperature value, the.attenuation of high frequency.* :.: \\": /::

<.-:.:~\\:~-~§~_;::~pressure waves is very high. *The LOFi :system*~as-desi_gned: usi_nQ'~HAM6 code.su~cool_~d ;... ~(:;::~~;--:~'.;:;\\\\ blowdow.n predictions* as for.ci,ng functions for. str(Jctural ~nalysis codes-~. The re-.~~;;*:_,:.~.*::-: <;;~~B~:-':._*,--:At.Jire*ments imppsed on tpe.\\&!HAM6.c(ll~ulations_ weteJm isoth~_rmar.sys~~m conditi()n~*:;.~;:.;:~;-:C~(",-. ~:_~*:Ei,=~:~;:;':' ~::.~.. very ra_pid l.On:iillisece>nd break op~ning time;_and no *pressure wave attenuation; .::_~:~~~+:.~,:~*

3f%;,tt\\:;:\\-'<. Consequently*,_ the system was* predict~d to re_rn~in.structuriilly.S.Qt.1nd *with a* large:.'"'* f*X~:"~:;-.'.
  • ~fr~~&:~:~ :, ___ l!largi.n of safety.

Me~sure!llents of str.!lin and ac~eleration ~b~ve con.firme_d this.. *:.. ::>-~ > *;=:

  • _.~'c;:,~lt;~:: s~mi~c~l°e_ ~ounterpart experim~nts_ to* L2-2 ~_an~*t2-{_~h-~~?'th~*;::~~m~~b;si 0

c _-_~_.~;;:?:.:- -i_<:-... _ * * -_'.

f.;;j~:~~l:Jiydtaul'iC-?phenomen~ *on approximately JhEf$ariliif:'t.imihg*** s_eq1.,1ence_.*c~e-feren~es 9, _

l.O)~\\C~:>.. *. -~.,""..

?~f~~f:t. W-~~-re: differences occur -~ney*_are-usualiY: attr.ib~~~hle**~.o ~overfi_.d(;l~ib'.flh.~-s~aling*'.:.~F<.-:

Jf:\\'.'.;'./:}~2~'.;_::/rationale (References 25, 26, 27Lstich as'preservationC(>f core.and doWncofuer. lengths. fJ;-~~£:'~~~~~3~:;* 2 d~~- '-~6-~a~ ~ :e, -cii:f f erence in results* wa*s* ~h~* 'ah~~~c~:'.*:~~-;.'::i~~ ~: i1y

  • que~~:b;/( ~h~-,c: :. :

~- -~~-..*. : * :,. <..

~
?,
::**::':~;* following possible reason-s. for this difference are *:being a~s~s~_ed: * * *

. '~. ':.... *. ~:* ~-

1. Differences.in core hydraulics;
2. *.Inherent differences between a Semiscale electrical heater.

rod and a nuclear rod;

  • 3. Stainless steel cladding as* opposed to LOFT zircaloy cladding;
4.

Power profile used in Semiscale to simulate the LOFT nuclear core behavior; .

  • 5.

Pump locked rotor simulation in Semiscale broken loop hot leg as opposed to a free wheeling pump simulation. in LOFT; . The fir~t.two items are considered to have t_he most influence. Calculations,.

  • ** "*.:- *.. using the INVERT code; and the actual hydraulics measured in the LOFT experiments

~ith the same heater rod power profiles *resulted in a predicted Semiscale -_core thermal response* that was in rnuch better agreement with the measured .~OFT core thermal.response. Also, the return to fluid saturation temperature was.. then calculated to occur. However~ sfmi*lar calculatfons witti' the-RELAP4/MOD6 code

  • did.. not show the return to fluid* saturation. Analysis is continuing in an.-..

attempt to explain this difference.

-~. \\ .*~. '..:. _-.. ~~~:'.'._ -_-.;:. -**11 _:.. _ f--~~::.::.;./ *,: **. Hf R. Denton -**

  • -*** *-~.,;.

. **~. :*..- ~-. :. ' ~::..... . :-~- *. ~ : *.. ........ *. _.~.. -~.. . *:. :. ~.. '.'

  • ~.:.~_: *- - The p_erforoman_ce of t_he _TRAC and RELAP4 codes in* predicting-the return of the-_~_:
  • cladding temper_ature to the fl_uid saturation value_-in
  • L2-2 and L2-3 is being
    _::,: --:. * >:-.:~s.tudiedv ;*Pr_eliminar:y *results show: that the <:l~<:fdir,1g* thernial response can be -
    -~.

>.:*:~alcu.lated by)tlodifying ~he_ h~at;*tr_a,nsfer *logic*jn-_ the( codes.-: This. can result

  • ** from a different s~lec_tion of the. transit;_iorl' boil ihg correlations, the minimum

- * * -film bojJing *point-, and the critical hE!at fluX.co(re1aiion.:* At this time

  • .-. Jnsufficient l>ost,;,CHf experimental data in t~e region' of low flow and low qual'ity h~ve.. been assembl_ed' on which to base t~¢ propf:!r heat_ transfer logic.
However, theoretical work is -~cmtinuing il'l this area ancj,---as experimental

-- data continue to be added~- the correct hE!at _transfer __ logic is expected to result~ . - ;.*... :~'., ~- ~-"'~ ~':... -~-,>-

?::~I:k.;~~~<:.:,':,A. 3 Commercia 1 PWR c~nside~atfo-~s--_~: *

,k\\~:~}~;~*'.'f{E~-~.§.~e.*z:~\\.~~~te}~~ ~iq'.,~'Ql~iclions...... ***.*.. **....

  • i+._.,

-.<:j5\\i\\~li.. f9urJridepende)it pr~t~-st bes.t~estini~te pr~dictions_'wer~tmade of Jhe*.. ~~:::3 ~ests9.

.:-.~*:-.-*'
~~..,!.'..,,::;::S?:S;.~~;_using the~ __ Cqmbu*stic>ti tngine¢ring BE -~9.de pac~age (Referenc:e 2s)'*;* EPRf',.s RET.RAN. ~: ~-z--::

~'-"-' *_ ~:J,X~~.:,~,*\\::iJ.-:,::::*(Refer~nce --2~t_~:_1N;L.- 1 s-FRAP--S3/RELAP4MOD_~* package_ (Reference* 30).::*and-"(ASVs::_.. _:\\:* :.~:~-: --. ' -

  • F;
    Li'.*{
    .)\\~:tR~C-P;IA (Reference.:3l):* A ~ri.ef comparisor(is giv~ri_}n_ (Referehce:;3*2r:and.c:
_t~~
~-~)tA~~'.~~r~=~~~;~:~JYAf i~~~!3-~~'.~~*~-~ci~*~-~~ ;.?? n4.~~1t~~* -l s-~~:=~d~~-~e i-~~-~-~-r~i~-~~~-~~~~g~:~?:~l~~~~---:.~::. :'._ -..

,:;;;>})/':i;;;~~=~< time**of *the_ -_f'.irst **ql1ench; however,* only ~he -CE. predict.fans.showed* a quench *at*~~, *--:

-.-=--~->:,*:_<..... "the high*-powered location,* and this was not core wide.

Thus,* all best-estimate* .. :.. ~* 3,~- -.-----~-'-- _coqes predicted g'eneral ly higher cladding temperatures than *measured.-_, -, -

  • ~:~)~.. ---;..- ~-:~_... ~/~:i-WREM. (Water Rea~~or* Ev al uat-ion Mo.del) prediction-wa~. ri1ade t6~~r2*~3::,*~Y oss. : *:
  • ,..... :-... -_-- Thus;* L2-3 provide_s a basis for the evaluatioh o:f the margin of conservatism in '->
- _the WREM code package.--* Analyses are'_ being _performed _withi_n.the Standard Problem>

- program and under the guidance of *oss to qual ifyjiarious conservatisms contained

  • in WREM.

4.3.2. Application to the Zion PWR _ Since L~-2 took place, several relevant improvements were made to the INEL -com.puter code* package~ The hydraul iCs had not been predicted correctly for L2-2. -: : ptincipally because of a la~k of* 1,mderstanding n~eded to define the values of

  • certairi inp~t parameters such as the critic~l flqvi transition quality and multipliers for the Henry-Fauske and homogeneous *equili.brium models {Reference 33).
    • '- *... Post-experiment analyses have led*lo signifi_:cant improvements such that best-estimate_*
  • predictfons -of*system hydrauliCs na*w agree very well with 12-2 *and L2-3 hydraulics

(~eferences 34, 35, 36).

  • Al so; improved understanding of the heat transfer surface

-. used. in RELAP4/MOD6, now perm1.t-'predictions of the early *cladding quench measured - in L2...;2 and 12.:.3; although, as discussed above, a:* better understanding is sti_ll being sought. _ _ The improved LOFT mo_del ing techniques have been used in RELAP4/MOD6 and applied to the ZION commercial PWR. Predictions of system therma_l hydraulics were made

~*. *- . using-L2-2 *anci L2:3 initi_al con-ditions:.. The rii~ss flowrate results w~re

  • divided by_the ZION.;.LOFTvolume*ratio for comparison tothe LOFT"results *.
::~*comparfsons of* the mc;>st significant thernicil~hydraulic phenome_na in LOFT and
  • .,,.:.'..- -* <>ZION,~are* _sht>wrr in figure 9 for L2*2 ini*tial-conditions, and in Figure 10 for
  • ~* *. "'* *.J.2-t.initial co!Jditions. Correspondi'ng toiTipari sons of LOFT predictions with
  • ._* :. ~OFT data,a.re ~shown i_n Figure 1 l _for L2-3 *. Comparison of corresponding
  • * * ~

curves ih _Figures 10 and Tl generally show a strong ~imilarity~ and the only . :'-~area :where LOFT data ahd ZION prediC:tions differ appreciably is in the core ~~hermal response. The predicticm shows that the cladding in the -. * <.',,hot region of the ZION co*re*does not return* to fluid.'saturation conditions

  • o.. ***-:-,- __ within the first lO seconds: of* th~. tfansieht with L2-3 initial *conditions *. However,

... 'as. s~c>wn :in Figure 12, the cooler reg_ions of th.e ZION tore.approach fluid ---~aturatfo'1 te_1_11peratur~: withi.n.. t.he* first 10 seconds~

  • Temperature turnover does

____ _ *occur ~hroughout the ZION c_ore-,.. _~l'.ld the* maximum cladding temperature is reached .;~~~~f::~:<::.~--~~ _ ---_-wi th1 n the first la* seconds-~:*_.~*:... -.:::;~;_:_.:-~:*::* ~*

  • * --***:~*~:-

~~~J;~l~{ /<b~e : impo~t~n t~-pa ~amete~-~iii~61:;~;J::~~ ~:'~f ~e --~O.ET ~ lI ON : comp at i s6ri* i 5 core, fl ow.:* -* *

  • _:: *.

.,.,.<::_::*."~*'.**~

,~]~~;£~.;;._
,
_:;::~:_*Jwo 'Se.pafa-te. scali.ng consi.de_ratiOns* *cause the.. LOFI.*core flo\\1 'to *b.e different,.,_,_...

__ ;:~,-'.0* ~i?i1t7::2tr;::,._;:_:;:fro!Ji'. tha(ln-_iIQN~-::~~-,~l.o.J*1:ia_l*lY~* *_~he_. int~ct_-loop?~

  • whi c~ r~present_s** thre¢ i_ntact:,;:f('.::f(~;;~:~t~I~:

:*::~:~:':~:?"./":~*::*_Lloop*s, m"Ust__carry :the flow of four loops because the broken loop is*quiescent'.*:-s**:.-~ --.~<::*:':',2:'f.~;;_ ,~~~11~;_3~*u@~~~2~~~6~~.S~~s.~-~~9.tr~~-~~~;~1}{~! 1 E~F1:'~-~~~v~i ~~t~u~-~tb~"~~~~;~~-~~ **:b~r:~~ pl:r~~~-t -~f --~~e *;.;.~_,~:--~~.;-- *** **

.,d<.--{:::~~::'f;ii-:;':' ZION.core: flc>w:.~/The'"'(:ombfMti'on of these* two effects results.* in a LOFT" core
  • ~:sf:<;:~:::~'.::,t:ft':tl.QW":wll"fch'*:1(~6l' :p~_rc~nt**~lower than.the* ZION value~ and* h-~nc;:e*conservative, by

-~--->-':*--:._::'comparison-~ ~.uring the.initial part of the test. An indica.tion.of this.'.. _,,~~~,;*r :.~*::.;:Y;':f.C:bnservatism* is'. shown by -comparing the LOFT results with the LOFT predictjons :~, _;~:,~-~*~*::i.-;.::;'~i/:T(Figure JJ where: tbe predictiQ.n exceeds _the meas~rerrientJ and then -comparjrig :.. ~~-- .-~r--:/J;:~~,~~;::;\\;::Jhe lPFl.,ineasuretn¢nfwith toe ZION prediction (Figures' 9 and lQ,*. where the:'

-:~:::~_*:y:*.:s:- *.. c:measurement.exceeds the ZION prediction)._-;.. :..... **. _ _..

/:~%i:~~*-:*~;t\\;~:U~\\h~.q.uestion ?f. the d.iffer~nt cQre leng~*h~- i,n:~*ol~~-d ~as been ~dd:e~sed in the -,~-

':;!~*::*',:;:;::"~**.;.;
  • _Sem1~~ale fac1l1ty.:*

Exper1m~nt~l results shown. ~~:F1gure 13 ind1cate that core

f:".'"::'.~~~~':t;;,:,. length.,does: not have a significant effect on-p"eak cladding temperature (Reference 37). -"** -*

,:~;~:F\\i'.~~~~~::::.*-~.The ZION stearn generator' design was var"ied as. shown in Table V to change ~;:-,w:4:{~_y:;,;. *;the *peysic.al properties affecting heat transfer-.* The Jargest change was to use the -~~~*:.::,~::--:-:--:<:.*. LOFT :steam generator tube design. The results* of"the changes to the ZION steam _::.::r* -*-gener~tors on the sy~tem hydraulics were negligible. *The* core thermal response

  • showed a ri_~gligible change in peak claddirig temperature except for the case

-- _involving.the LOFT steam generator tube.design in which the peak cladding .*... *:_temperature showed a decrease of 50 l<. :However, as discussed above, the LOFT

  • predictions ~how higher.pe~k cladding temperature *than LOFT data which in

- :; turn show a ~igher peak cl add frig temperature than ZION predictions. We

"_.. *conclude th~t the* ~oml>ined eff,ect _C>f the v~rio_us scaling discrepancies is
  • <to prQduce a conservative.indicati-On of PWR core thermal response. The
  • details of the ZION calculations are being prepared for publication.

_..... _--:_.: ~-:.. :. ~. *. ~**, :*"*. '.. -~-. -~*..... ~ **-. -*. *_**e****. t**."' ... *.~.... . -... *:. :.:~7..... - ~- ;:,.-.... ~-:*. -..;' --~_:.**: =.->-.. ~*, .. ~--* '.

    • * * -:~- The *results of the LOFT exp~riment$ described in this letter are applicable'_--

.*. ~

  • .-*: tQ Jarge co,d-le'g, breaks *in the_prJmary piping coolant loops of PWRs.~* They-.

~:~:<~Are** re_Gommejided for "use* by_ NRR *1n its. interpretation.. and application o*f. _;..-:.~.. -**:._ *1ocA ECCS evaluatfon model criteria and related codes.*

  • 6. 0.. FUTURE PROGRAM*
i~l?ii:/'"*~*:;-:::** *The tests remaini_ng in *the la.rge break power asce.nsion series *are designed
-.,
...,,~:;::~:~: * -. to *
  • __.. ** *.* :_::-."):*.. ::... _'._:~_:_.-~*'.:._:;;:_:.'._.. **,.. *_,**.*_;_;:_~*._.:,_._.- __.*... _..

~~{'.::~~<~~: ~-~.. *: .: ~:~. : *_.. :' _,.. ~ ~,_ :

-* ~. ~-:....*.., :L,~-.::::.e';~~--:~::?---5*"~\\ *- -. :>

_.' ~>--::: .'.~-.>.~:-~- ~-.{i) L2-4: *. evaluate.the--C:ore.thermal. response to.. lrt1Cicf1lf.9rt~1'~pow~r.. : increase~:_,,;::;~~ '..~=-:*:~-:. ~-: *.. __.. '"_ - ~-*.. (i.e.,. to 52. 5_J<W/m, equi_val~n~_.JtfJ~~ -perc~~~ )i0.~l'-J:.u1J power )_t*:~-~-~: )::_2 '::.:;yt.:':>_<::*;*...

  • _tests~.- have be~1f9sed ih predicting the results of the rernaini_ng.tests; _these ~::?;'"::_~;;~:!f.01&-f?
{l~1
~Z~L****** ~~*s~~~f ~~i.** !~c!~~

1 i/ihe ~~~~*6~"~~~5 f~~M 2 t~0'{j ~~~~n:r~O:;r:~e~t~~ to ; 5 ;;'5}ff I;~

  • i.~;;it::t"::~;'.:: *
  • expe~ted t() r~~~h* a maximum at~ much later time and reflood several seconds.

.~:-~:S~:_r.-~;;':=;:*.';.~,J ater. than.* any.other test-. in,this.: series/. : The importance of. p_erf ormi ng the

~;i}~~;:;:,.::~*;F~~;<~bove.tests --whkh remain in the power _ascension series 1 iesin the extension; *
~0~~~r~-;
~-~-\\:?' of the range of conditions over which our conclusions and codes can be

-~

~;
;(.:;::7.. ""':*: :. -~emonstra.ted tQ be applicable.
~
*:[:*~::_..".- ::*:*

1:

~
-:~.: *:
  • _; C*c B~cause of the TMI* q.ccident,
  • t:he focus of the LOFT program has shifted
    • ....* to the small break experiments*.: The existing t.e,s.ting sequence is, there-
  • fore,. revised to* reflect this shift. : A new experimental sequence has tentatively
    • be.en defined, *as shown in Table Vii, which advahces the. small break experiments

.* ;$ucti th~t they begin* this year*~. Pla..nning for these small break tests is based on . input from your staff (Refere,i*rc~ 38) ~ vendor *recommendations (Reference 39) . ; and review group advice (Reference 40).

  • Information o*n small break tests should be available early in 1980.

. ;~, ~:-II**--*---*

14.

~* *-.~-...... _....

  • ':'~.. ':":!""
  • r** *;.--*~: "

~~~-::-. ~-* -~~* ~-' *.. -**~ .. ~'.

-.:*--:~*-*.

--;:.~ *::- -*. ..,_.. ' ' ___,_~*-*.:.:: --~---- *.. . - ; ~*.........

~'--*.. . **"fl.: ~;1.. ~** Intact loop Steam INEL-8*10057*.2 Figure l. LOFT System Configuration

r-.* l.*t~:l:A* ~ ~i::J';,f i::r* ,.,:'";"< ~... ' -~-:~ :* *:* .)*** .. ;,~~*-. l* ~ ;.~-. ~ : ..:., ~- .\\ INEL*A~901 Figure* 2. LOFT Core Configuration* -i:.. --,i~ *. ._, ___ i:

.. ~ -~. *. -"-.... -.:::-'**~: '*. o.. a* ~~" -*~;-.-,

  • -- -Ftgure*3. LOCE_ L2-2 *Axial Profile of Cladding Temperature in Fuel Module 5.

Figure 4.LOCE L2-3 Axial Profile of Cladding Temperature in Fuel Module 5. 800.

IC 700.

Ill llC

I...

~ llC 600.... A. z Ill... ~oo. Ci Cl ~ u ~ -. *-.

  • ~I *

.*,.. I 1000. 900. 800. ~ ~ a: ~ eoo. ~ Q Q 900. ~ I*

      • -k

. r*

--~ *... - 1100 _:: _,L~ tooo ~-- ~... -.. I - " I~ >-" e Q).**- 0.>. 900 *. _. ~ ~:* Q)" CJ

  • aoo*
  • -r:

--a r:: .:g 700

co
  • u 600 LOCE l.,.2-3 50Q'--~~-'-~~--L~~~..A.....~~--'-~~---"L--~--,....L...~~--"~~~

0 2 4 6 8 10 12 14 16 Figure 5

  • External pressure (MPa)

. Temperature-Pres*sure Hi story of fyel Rod Experiencing Peak Cl~dding Temperature During LOCE L2~3 Compared with Modes of Cladding Deformation (Ref. 19).. INEL-A-12 309 -~---..-. *.... : I

~- -~.-:..... 0'--~~~~~--'-~~~~~~1-.~~~~~--L-~~~~~--' 0 10 20 30

40.

Time after rupture (s) INEL*A-13 390 Figure 6. LOFT Data and LOFT Best Estimate Prediction of Lower Plenum Mass Inventory in LOCE L2-3 ..J

  • -."';**=-**.:
  • ** **A

~ z w ~ 0 0 -*4 !IO i*I 40

  • ll 0

I

  • 30,__~-'-~~-'-~--'~~~~--.L-~-'-~~-'-~--'
  • 1 :*

/ .t' I

  • I I

"~ ~ ', \\' ".; '. r * ' I t ~ ! I*,. .... '~ ' '. '. '~ ;; '. 0 8 i 1 * . 0 0.2$ 0.!IO 0.75 1.00 1.25 1.50 11~ 200 0 0.25 0.50 0.75 1.00 1.2$ . 1.50 1.75 2.00.0 . 0.25 E.tewal1on lfom core bOttom (m) Figure 7. Elevallon lrom core bOllom (m) Fuel Cladding Q~ench in the LOFT

  • . Core Compared with the Refl ood Rate in LOCE L2-3.

~. - Module3 0 ..e

  • O 0

0.50 0.75 1.00 1.50 1.7!'> 2.00 Elevalion from core bottom 1m1

I I

  • ~*. '.* i ao.o,......,~_,1..

....,1,.....,...,. *.,.. 11~...... ~,,....----~---.--..-...-0t"!'........,.............,.....,....,,._...,...,*~.~......-........................,........,................. ~,.........-.,....... ~~...,~

  • I
  • I* *.I 1:1

.J:: --*I. *.1' ~,_*I lJTI _. 1,.0CE Ll-5_ --..,_ LOCE L2-2.-1-......+~f'-f-++-1-++..----+--+--f---+'~!4..H----+--+--+--1-+..+-1 .. -1" ~-*-t--1--t-...... ~T:H

  • ~** r----~

.. "1---"t"'~t--~~~ .. + ...+ot~,------t----+--+-+-+-+-+-t..... --.... --"---+--+....a........-....i1oo1-............................. -.1i-i**~;o1-1.~............................ --1~+-~~.+.~.~ \\ ...---~lr-t....,...-+....,..t-t-it-++t".'H,~.....,...--1---f.;...,...-t-.f,-..ll-++-f+-_,.--.....,..;...;,...J-.....+.o,..l....... ~-+l~---J..,...~l-,-+..+-ii..-1-f-~----1...... -t-~J.-il-f~+-H* ' 15.0 ~==::~~ 8._i:::1::~t;i~~i:;:*:*---....:;;~;t:::::t::t:::t:::l::ld~t:::::::lt::::*tll:;t:~*~**~;~'.:j:+/-, .. 1:t:t::::::::::'t::::t:;j~t:t:l:i:t:l:::::::lt:::::t::t::J!:ll:l;t::tj .r '~......... I ., "-......'\\... LOCE L2-3-t--t-+-t+t+---"t'~,~ ~......,:-+-++++.++----+....,..-+-t~;;..,. ...,_,.-f .. ~1+---..+-+-+-f-~1-f..,,M-....---+-+-+-+-t-+++1 ....... --... _.................. +-+--llo++t........,. __.._ __......... ~~-+.... +++------+~-.&--......... ~,~**.,.................................. ~~ ................. __ ~ .... ~ ...................... -+I r---.,.......... r-,..;--t-tt-tt---~t-_,..... *\\rt-*,...,,,..'"'c:+-tt++----11--* :*Loce'~i::~*s3:.,,,.~---1...... -....... +-+*-i***...............__................................. _..~~ \\\\' .'\\.

~i----+---tl--+-+-t-t-+-i--------11----+--+--t~i-t.... ++------... ---t--.............. +-l... ______..., __..., __._...... ~~+-------~.,~~...................... +-ll-C

-'\\'~ 1--~-.f----1~+-+-+-+-+-l1-t-~--+-~+--t--t--+-1~++-~-+~-+--+-+-+-+-+++~~--1--+---1~.LOCE L2-3~-9~~,,~t-t-f-t-t-H 111111 o.o....... ...,j..........................................................................................................................................

    • ~*............................................

0.0010 0.0100 O.IOOO 1.H TU* Al'KR llW'Tim CKCGIGSI Figure 8. Pressure*as a Function of Time for LOCEs Ll-5, L2-2,. and L2-3 ,..:. ;. ~

~.... i ~ ~* a rt... "' I c II: ~ c a:

  • . o O.!I o.o 0.15 0

1500 0 1!!10 -eso 0 1.0 L2-2 Experiment Zton RELAP4/l<<l06 ~.... i I!! Q o.o 0.15 15 10 115 20 25 30 0 !I 10 l!I 20 !I Tl"E.Al'TER RUPTURE l t 1 lllTACT LOOP COLO LEG DENSITY L2-2 hperlment Zion RELAP4/M:l06 10 l!I 20 TllOE Al'TER RUPTURE It I IHTACT LOOP COLO LEG M.\\SS FLOWRATE 10 1 LZ-2 Experiment 2 Zion R£LAP4/l<<ID6 l!I 20 Tint ArTER RUPTURE ltl DIFFERENCE BEMEll IllTACT LOOP AND BROICEN LOOP COLD LEG HP.SS nOWRATES I:! ~ ~ ....... I 2!1 30 ~.. c R i...... i i 25 30 . !100 0 0 1100 800 !100 0 Tl"E ArTcR RUPTURE l t I BROICEN LOOP COLO LEG OENSllY

  • L2-2 Experiment Zion RELAP4/l()D6

!I. 10 l!I 20 Tl"E ArTER RUPTURE l t I BROKEN LOOP COLD LEG Kl.SS FLDWRA TE 10 L2-2 Experiment Zion RELAP4/l()D6 15 '10 Tl"E AFTER RUPTURE l*I CLADDING TEMPERATURE IN THE PEAK POWER REGl<JI Figure 9. LOFT Data and Zion Prediction Com-parisons for LOCE L2-2 Initial Condit ions. I 25 30 25 30 25 30

Z!IO. l2-3 Experiment Zion RELAP4/1()06 1000. w c c c...... E w '750. 0 c .J u I; 1! i I '.J L2*3 Experiment Zion RELAP4/H006 -eoo.L-~~.i..~~-'-~~....1~~~.... ~~.i..~~-' 500. i!O.O 10.0 15.0 o.o e.o 10.0 l!l.O i!O.O i!!l.O 30.0 o.o 5.0 TlftE A~TER RUPTURE l*I

  • DIFFEREMC£ BE'TllEEM INTACT LOOP AND IROICEll LOOP COLD LEG MSS FLOWRATES Figur~ 10.

Tl"E A~TER RUPTURE Ill CLADDING TEMPERATURE IN THE PEAK POWER REGION LOFT Data and Zion Prediction Comparisons for LOCE L2-3 Initial Conditions. i!5.0 30.0

I .. - -*~

  • -:* :~;.~:..

!;_:.,~.~: . ~. -.~.* . *, ~...,.'. 1.0,.................................................. _. __.., __________._..., 1.i~*3 Experiment 2 l2*3 RELAP4/Kl06

{,

.R J,,'-~ij;5..-1-+++-IH-.-l1Nl-l','lfltl.;..*H+~1-+++-1-+...,_ll+.._-l+IH--++Hlt-I . ;t: :,,-,,...

    • 1~n I"

-.,'.*.... :;1-:?~;*~1*.iijJj~ttfi--i.

  • l* ~~~~~-'~i~~~~t;iiiw~~*~*--*

a j

  • -o. 51.._........_............,..._......,........,......,....,...,.'-'-.... _,_......,.,._...,......,
  • . *a.o 11.0
  • 10.0 l!l.D 20.0 2!1.0
so.o T lftE AF'TER llUPTURE C 1 I INTACT LOOP COLii LEG D£NSITY

!100.r-1-,-.,...,l"T~r-T--_...__..._.... __,... __,......,............ _, 1-11-+-++-H-++.,, LZ-3 EXpertnent L2*3 RELAP4il<<>ll6

  • ~11*0 **""'*""""'"'"".............................................................. '-lo"-1...o.;.i..I O.D

!l.O 10.0 l!l.O i!O.O 2!1.0 30.0 Tift£ A'.TEll llUf'TUll[ 111 INTACT.LOOP COLO LEG MASS ROWRATE

  • 2110................................ _......,._._.._....... _..... _._.... _....,

L2-3 Experiment

2. LZ-3 RELAP4/l<<>D6

. r. '. '~. L2-3 Experlr..,nt L2-3 RaAP4itrl06 * ~~ I! ~- .: :::,,:~;~ ~,l1 jj ._ ttUt!tilf:t!ii~~=~~~i** j..... .i I . -o. !IL.l...a...I ,. -'-'~.............................................................................. o.o !l.O 10.0 1!1.0 20.0

211.0
so.o BROKEN LOOP COLD LEG DENSITY 1000.r-1-r,-,-;-T"il"T""""....................._...............................,

~2110 :tt:t:l:!:ljj:t:ltl:t:ttt:t:t:t:tjj::t:Jt!:t:tttW o.o !l.O 10.0 *. l!l.O. 20.0 2!1.0 JO.O

  • T iltE A,T[ll' llUPTURE.. 101 0

BROICEN LOOP COl.D LEG IWISS FLOllRA TE 1000.f~t:EI:t:J:El:-""'.'.... --~~~:;-;;:;;:;:;::;;;......... ~ .... :J L2-3 ExP.erfment LZ-3 RaAP4/1<<>06 . '.,, -~ 800.. . w.'- ~

    • ~:.

100,:

  • 1. '.*

i l , ~ -~!ID. H.-4ll'Hl-+++-t-++-t-+-+-+-IH-+-+-t-++-ll-+-+-+-t-++-H ~...,,. --' : ~*, 1~~~*:**: ~~:;:*:* a.i1-+-+-l-~-++H1-+-++-~-+-l-H-+-4--Hl-+-f-+-l-+-f--f ~500.IL.l...L."'-&;..&..r...1..11...1;.,.i...i..1...i."'-i..i...r...1..1:..i."'-l.l.-'-.l..l-.r."'-~

  • a.o

!I.a 10.0 1!1.0 20.D Tl~E AFT[ll llUPTUAE 111 ~.. eoa*_. 1tOO. o.o. !l.*O 10.0 1!1.0 20.0* 25.0_ Tl~[ AFTER llUPTURE 111 DIFFERENCE BETWEEN INTACT LOOP AND BROKEN 'LOOP COLD LEG MASS FLOWRATES CLADDING TEMPERATURE IN THE PEAK POWER REGION i Figure 11.* LOFT Data* and LOFT Pre- .: diction Comparisons for LOCE L2-3 .:so.o

~:;. .**~ 'L, *. ** Fig*ure L

12.

Zion Predicted Axial Profile of Cladding Temperature 800 *. -700. 600. o.... --~--:.. - - " ~...... ';:)"'.* . oC. ; z 8 oC .J' U* ' i

  • I.~~,:*-:. *, *,'

~

  • ~ *1,

~.- Q) a.. ..aJ250 m ' a.. . G>, ~-E ' ~ *:--G> 1000 I L:;.* . 'Cl) <U . Gl ..s::. ' 7 50 Q)... 0 0

  • ******* Short core (Mod-1)
  • -Long _core (fv1od-3).. ***.

'; ~. : ....**. ~.... ~.. ~~**********~~***~* - *. soo------~~~~"--~__._~__..~~-'-~~ 0 10* 20 30 40.. 50 Time after rupture (s) 60 70 INEL-S-19 603 Figure 13. Measured Rod Temperatures at Midpl ane of Semi seal e Core

.~
  • .. *.*\\*.,

TABLE I S'f'.ST~._coNi:rG_!JRATION AND INITIAL CONDITIONS : . FOR NUCLEAR LOCES LZ-2.and L2-3 Parameter. . *lpe rea :* *

C:ocati()tl.
  • .. Size* *.*.. *
  • *opening _time (_nis)

LOCE L2.-2 co.ld leg

  • 200%
17.

Primary syste111. pump operation:

  • Powered to To + 200 s
  • B~oken_ loop pump _sfniulat.or*'
  • Operating pump K
  • 9.95.

Intact loop. resistance 'Law* resistance K

  • 131.°7 ECCSs

~ _ HPIS, LPIS, and ECC injec~ion location

  • ecc* actuation mode:..

... Accumu 1 a tor . LPIS HPIS Steam gen~rator s~ondary:. .. :t* ~,,'. *Press.ure (MPa).. **. ***** .. f'low ri!te ( kg/s) --. *. Primary sYsteni: Pressure (MPa) Temperature (K):

  • Hot' leg
  • cold leg
  • Core poWer (MW)

. MLHGR (kW/m)

  • Mas~ f1 ow ( kg/s)

Soration (ppm) ECCS accumulator:.

?,.essure (MPa)

Temperature (K) . Sorati on (ppm)*

  • Injected volu1J!e (m3)
  • Gas volume (mJ)

..... \\',.

  • .* 1' accumulator Int~ct loop co.ld leg Pr~ssure.* '.' * * *.* * *
  • Pressure-level*

-)ressure-level -~ :

  • r

'*. 580.4.-3 .. 557.7.! J 24.9 + 1.0 26.4 + 2 194.2-+ 16 838 + if . 4.11 + 0.05 300.8-+ 3 3301 +-19 1.68 + 0.03 '1.05 + 0.03 LOCE L2-3 cold leg' *..* 200%

  • 1.7.i

,_.- *:.1.

  • . Power.to r0 + 200.s *' _:;

Operating* pump ~ '"*9.95 *

  • LoW resistance K ~ 131. 7 HPIS, LPIS, and * *.
  • accumulator Intact loop col.d leg

. *.. ;*.,.:..~. ~*'.::\\.:;_.~.. :. -* Pressure. *'t.*: *;:;-- . Pressure;.1 e*ve f < * -.' Pressure-1eve1 : ~*: 5~*18 + o.oa < 19,S ! 0.4*. - 15.06 ! *a.OJ. 592.9 + 1.8 **. 560.7 ! 1.8.* 36.0 + l.O*

  • 39.0 + 3.0 199 +-6~3 679 + 4.

4.18 +. o.os 301.8-+ 3 . 3281 +-17 l.71 + 0.03 . 0.96 ! 0.03 ~

  • ~arcy K factor based on 0.016 _rn2 flow area *.

~'- '* ,. -~ . *' ~'

  • 1 *
  • .. i

.1.*

.~:*,.. '._:

TABLE II LOFf. SEMI SCALE.. LPWif' SCALING* PARAMETERS ' '('

  • Vol 1111es
.*, Total PCS (m3) l

.*.*.Reactor ve*sse1**c% of PCS):

  • Intact Loop (% ot PCS):
    • arok~n Loop (% of PCS) {

PIJWer (MW) Length of Active Core (m) Seniiscale

  • 0~23 37 44

.. 19 ': '

  • .*~;.(>::.*.
    • . ; "*i:sf and-,3.66 7.80... -

34

  • ' 47

'19 so ' : 1.67 '347 38': 51 '11 .3400 3.66

  • ~1 Rrti~
~

.: Volume/Power (m3/MW),. ( *

_ *** * *. *ereak Area/PCS Volume (m*l). _

. * *

  • PWR Vo 1lJlle/\\lo1 ume
  • ~. '; 1-.

0.14' '.* ' 0.0026 -1530; -.

  • . *\\...,.

....,... ~.- ':.*:. ~HRO_NoL!lGY. o.Fi EVENTS foR N~C.LEAR' L.ofr L2~2 AND _ l.;2:-3. WI1H:NONN4CLEA~ LOCE. Ll,.S ~OMPARATIVE VALUES.. * ~. '....

Time _After LOCE Inf ti at ion ( s)

Event lot£ 1n1t1ated tOCe:* L2-3

  • . LOCE' 'L2*2 '

.o..

  • -o LOCE Ll-S 0

0.10..

  • 0.0026 1

Subcoo.led bl owdowri ended a. o.os****'

  • Q.07.:
  • . Cl.1.

0.087 ..

  • Re'actor scram* :signal. received 0.103 _,.

'0~085 ,.,.;,*Tt"*. ~. at contra 1 room 1

  • _Earliest depart~re of cladding ~ernperature

-~-,'.0.9~* :"'*"< ~

  • from fluid saturation temper:ature (Tel ad > Tsat) -

.. ~~: ~- * '*,. Con~rol tods ~ompletely foserted,' 1.683 Subcooled break flow endedb 3.0

  • Ma.iciriltin cl adding temperature.
  • l:

4.95

  • attained.

.. Earliest i:ore~wide return of cla~d1ng - B.5

    • telilpera:ture' to fluid saturat'~on temperature HFIIS frijecti on initiated 14

. Pressurizer emptied

  • 14 *

. ~ccumulator *injection initiated

  • 16

.LPIS injection 'initiated 29 * * . i.;ower plel)um filled with liquid . 35. ~aturated blowdown ended.

  • 40*

~~~:"~~~~ ~~~~~~d~~ow e.nded.* :*]: . ~~. :,

    • - " L725*

3.8 5.8 8.0 12 ' 15 18' ". '29 **: 35 .*.~ 44 ,'.* ;~*' 25.6

  • 1~85' 0 1 '
te-~dY. state *;.-
  • value at time 0 4~
  • _.: 13

'14 ' 19 34 . ' 37 ' 47 54 59

a.

Enc;I of subc.ooled bl~down.f~ deffiied-H the oecurrence of 'th~ first pha~e tra~si~i~n* in

the system other than at ttie pipe break location. * *

'._.~'. . ~-**." : J" . *b~: End of subco9led break flow.is defined as the completion of subcooled fluid discharge from ~he break (hot and cold legs) in the broken loop. . ~... .,. ~. ~* -~

~ :..

... : ~. .. ~*-

  • .e TABLE IV.. **

SUf+IARY OF LOFT NUCLEAR . L'OCE RESULTS * /. ~xperiment Results

  • Times for> cladd1n~f temperature to ex~eed fluid saturatfon temperature (s)
  • _mi riimum *1!1. hot. region maximum fo hot reg i on.
  • Peak cladding.temperature Core* reflood rate :. (m/s)
    (K)

Miil.fqium mass/volume in reactor. ves~*el (kg/m3). Accumulator flow clJratfon.* _:: (s) :{ ___.. **:, . Maximum ac~uRKJlator fl~/~yste~ voruineo:-~..

Acc!Jm~la~t9r.. polytrop1c gas c*o~stanti. *

. Claddfng:*~u~n~~ tfme/cor~.reilood t:f~~-

  • ~cc bypa~s-at end Of acciJmula~Qr flOW. '.. C;:,**

(% of to-tal ECC injected): First 10 s -of the.transient . Du rat ion of primary punp press~re differential (s)

  • Mass. fl~w rat~/system volume 11 Irdt fa 1 value intact loop; cold leg *
  • (kg/s/m3) *.

Maximum value (t>O) broken loop cold leg (kg/s/m3) .. Tfme fnterva 1 cmsLct.>rfl1u:p* ( s) nm~ inte.~va i (ril1Lct.>rilBLCL)*

  • ( s)

Integral rilBLCL (kg/~3)

  • .Integra 1 rilILCL (kg/m3)

Differenc.e in m integrals;: . (kg/m3) i'. .. St9r'ed energy removed * * (%_of nuclear heat source::energy). BLCL ILCL broken loop cold leg intact loop cold leg~ LOCE L2,;:3 0.94 1.84. 914.:!:.3... 0.10 !: 0.02 431 !: 75 LOCE L2-2 . 1.00 . 2 *. 30 ]89.:!: 3. 468 + 75 29* ~. -

  • -* )~ *-- ~ - *. :_ -'.. *'. -'

..~.. 6.42.:!: OAS 31 --:. -~* ; .~..... ~.. 1.7i+/- 0.45 . ' 1.25 +/- 0.02.* " *. *.. *. 1-.22~ '0~02

    • <l 'tor all measuremen.ts.
  • 36 !: 4

...

  • 0 to 9 96.2' !: 14.4 to 3.65 3.65 to 5.71.

323.6.:!: 22.* 7 . 231.6.:!: 16 ;2 92.0.:!: 27.9 -= 64.

  • < 1 for 'a~n measurements 32 + 3 0 to 8

.. 24.9 !: 2.0 60.8 +/-. 9.1 to 3.60 3.60 to 6.16 254~7.:!: 17.8 215.0.:!: 15.0 '39.7..:!: 23.3 -=:' 65 -o. . : '*~ * ~ '. :"' .~ :_

l TABLE V

  • ZION STE.4Jot GENERATOR PARAMETRIC VARIATIONS.

' FOR. T.HERMAL-HYDR.AULIC EFFECTS ANALYSIS... Steam Generator Parametric Variation

  • ~hysical Change Tube mater i a 1 changed from Inconel Thermal conductivity decreased:

to SS 316 at 478 K 10.61 Tube geometry unchanged at 589 K 13.91 Heat capacity increasedslfghtly -'* -~* at 478 K negligible:* at 589 K 1.3 I Tube geometry changed: Heat transfer area reduce~: t

  • **.* ID increased from 19. 7 rrm to 22.2 rrm Prim!!ry side 13.4%.

OD increased from 22.1*rrm to 25.7 rrm Secondary side 13.2% Number of tubes decreas_ed from 3250 to 2430 Tube material unchanged (Inconel) LOFT tube geometry used: Heat transfer area increased: 10.2 11111 ID primary side 92.~ 12.7 mm OD secondary side 112.4i Number of tubes 12050

  • Tube materi a 1 unchanged (Inc one 1)
~_

Experiment L2-5 l2-6 t" \\ \\. TABLE VI EXPECTED RESULTS OF REMAINING L2 LOCES Vari at ions in initial conditions or system configuration rela.tive to LOCE L2-3 ower grea er Mass flow 25-30%.greater *. Core. fluid temperature differential

  • .remains unchanged.

Pumps.tripped at experiment initiation. HPIS and LPIS delayed. A 11 *initial condi-. tions are unchanged. A 11 conditions same as in L2-5' except pressurized fuel is used. Expected differences in -resu 1 ts re 1 at ive to LOCE L2-3 . arne

  • y rau 1c p enomena.

Similar fuel cladding tem-

  • perature transient with a peak value of 1100 K occurring at 5 s and core wide return to fJu id saturation by 9 s
  • Subsequent clad tempera tu res lower than peak value during blowdown.

Core wide*

  • .,cl adding quench _by ECC by
  • 60 s (5 s later than L2-3} *.

-In it ia 1 c 1 adding temperature response.will be similar. : with the clad temperature at 5 s possibly up.to 30 K higher. However, there will not be a core wide return of cl adding temperature to flu id saturation temperature

  • . in the hot region.

The* cladding temperature wi 11 - reduce 100 K by 7 s followed by a gradual

  • increa~e to the peak value

. of 950-1050 K by 35 s. ECC

  • .. quench of the c 1 add fog wi 11 be complete by 65 s.

Thermal response is expected to be the same as in L2-5.

i I . -IE.SL. : _: -JAHGU DATE* L3,-

  • 01-' 16-80

" l.3-5:.*; > - 07-80

'~..

- U-6 :, ---. 21-80 _,(6-l; --~~----. -. 05-09-80 ~:. ~. --.--, - .*: i.3-4:';.;;:": ~Jl5-16-80 L~-2 07-01-80 -LS-1 01-81 L6-4 02-81

LS-2 _-

.- 02-81 L6-5 oq-s1 l2-lf 81 l6-6 01-82 l2 01-82 -.. L1-l 05-82 l7-2 -. 07-82 l3-7 10-82. u-s*- .-12-82'. {. _,,,,,,.,,~ . :~, -: t*: ~. . TABLE~ VII ' LOFl FY 20 TEST s~aurn~E AND TARGET DATES.... _ eowrn U:.VEL (nlil. .~:>*, *-, ;._ *coMMErns MW:' liliLM. JiliL.EI. ~ : - ' 50_ . 52.5 16 ~>

.:c.sr~~~~---~~EAK COLD LEG.

BREAK FLO/l GREATER -~HAN> . : -.. ~.. - HIGH PRESSURE SAFETY WJECTlON FLOW, so.. 52.5 16: *.. Sr~ALL -~REAK COLD LEG., H1GH PRE&SURE SAFET~-~-- 0 0 o. 0 0 0 37 '39.4.. 12.:: 50 : 52.5 16_. 37 .39.4 ,12. 50 52.5 16 , :-* :.> INJE_CTION FLOW. GREATER THAN BREAK. FLOW, ~..

~MA~+ _BREAK ~OLD LEG~ PRIMARY CO°.LANT PUMP~,-~FF.:.;:_*

SMALL BREAK COLD LEG1 'PRIMARY COOLANT PUMPS-ON.~*:.** *

ir!:::~/::::::::;,r::~~:/::~.~~.~~if.f

-- Qp~RATlONAL TRANSIENT 1 io-ss OF rR;MARY*-*coq4~t>- _F_l_ow.

  • "<. --' ~

~-

  • SMAl~L sREAK cOLD
  • LEG~ *
  • H1 GH PRE~ SURE s"FETV -i: ;*:*~~.* - *

.)N~ECTiON FL,OW EQUAL TO.. BREAK FLOW, .,.~:-,

  • oPE~ArioNAi:. TRANSIENT~ *i::xcEssivE LOAD INCRE,AsE~- *;.. :. -

I * *

37. '39,q

~7 39~4 37. *- 39,q 37 39.4 37 39.4 . 49 51 *. 5' 37 .39.4 37 39.4 37 39.4 37-39,q 50 52.5 50 52.5 12 . 12 12 12-12 '16; '12.;.,,~:- ' _,.,*:'"{~~6\\~ DOUBL~~ENDED-COLD-LEG BR~A~ AS [2~..3--':~:. ~--:::;;:. ' -:' "sut:wl_'rH LOSS OF OFFSITE POWER;

    • INTERMEDIATE BREAK *uNsPECIFiED At THIS DATE/:

OPERATIONAL TRANSIENT: ROD WITHDRAWAL INTERMEDIATE BREAK UNSPECIFIED AT THIS DATE. ~.OPERATIONAL TRANsieNT: Loss oF ~EED'~ATER -* 16 K~llFT 200% DECL,. OPERATIONAL TRANSIENT: UNCONTROLLED BORON

DILUTION, 200% DECL WITH PREPRESSURIZED FUEL.

12 12 12'.

-STEAM GENERATOR TUBE RUPTURE & lOCA, 16 16 STEAM GENERATOR TUBE RUPTURE & LOCA,

--SMALL BREAK UNSPECIFIED AT THIS DATE, SMALL BR~AK UNSPECIFIED AT THIS DATE. - *TARGET DATES ASSUME NO SIGNIFICANT PROBLEMS NOR PROGRAM CHANGES ~-....

-1£... REFERENCES _ _ l... D. L.,Reeder, LOFTS.stem*_and Test Descri tion. (5.5 Foot.Nuclear .. ---*Core* l toss.;of.;,Coolant Ex eriments TREE-NUREG.. 1208 July 1978). _ 2~

  • G. P*. M.cPherson_, The Purpose of the LOFT Program and Its Applfcatfon

_: __ "to _Licensfng Acti:vfties, presented at.the Institute for Reactor

  • - Safety,* Vf enna, Aust r1 a, (~eptember 20, 1978) 3*. _o; L Reeder and V. T. Berta, The Loss"".of-Flu-fd Test (LOFT) Facility,
  • _presented at the 14th Intersociety Energy Conversion Engfneeri ng Conference, Boston, Mass., (August 6-11, 1979 J

.4 *. Research Information Letter - #137 LOFT Reactor Safety Programs* Re~earch -

  • Results._Jhrough Octo_ber 1, l978.

5_. I,.. J..Ybarrondo, s. Fabfe~ P,.- Griffith, pnd G.* D *. McPherson,. Exa*m1natfon

  • _* _ of LOFT Scaling,. presented at the ASME Winter Annual Meeting, New York, * :_

N~w York, (November 17-22, 1974).

  • )

~ . 6 *. L. J.- Ball, et aT,_Semi'scale P:rogram Description, TREE-NUREG-1210, (May 1978).

7.

~. McCormf(:.~"".B(lrger, E.xpertment Data Report for LOFT Power Ascension Test l2-2, NUREG/CR-0492, TREE-1322, (February l 979).

  • . 8 *.

P.* G. Prassfnos, B. M. Galusha, and. D. B._ Engleman~ Experiment.Data Report..'for 'LOFT. Power Ascension Experiment L2.:.3,

  • NUREG/CR-0792, TREE-l326 (July 1979).
  • 9.

.M. L. Patton., Jr.,_ B. L. Cql lins, _and K *. E. Sackett, Experiment Data _Re ort for.Semiscale MOD~.1 Te.st S':"'06.;2 (LOFT Counter art Test),. .. *

  • REE00 UREG-*. l 2.

August 7 *

  • lO. -_B. L. Collins, et al, Ex erfrnent Data Re o.rt for Semiscale MOD-1

. Test s.;.06-3 LOFT Counter art Test '_NUREG/CR;,.0251, TREE-123 Ju y 9 8 * -Jl. R. L. Gillins, K *. E. *sackett, and c. -E:.* Coppin, Experiment Data Report for._Semiscale MOD-l Test S-06.:.4. LOFT Coon'ter art Test); TREE-NUREG-1124

f,. - ~ *...

. 12~

13~

  • L,;.J. Siefken et ~1;. FRAP~T4._.::.**A Computer Code for.the Transient.

Analysis of Oxide Fuel Rods, CDAP-TR-78-027. (July 1978).

14.

Los Alamos Sci~ntific laboratory, TRAC-Pl: An Adyarrce*d Best Estimate . Computing Program for PWR tOCA~_Analysis,' LA-7777~MS', NUREG/CR-0666 (April 1979}. <.:.. JS *. Lo.s Alamos Scientific Laboratory, TRAC'.'"elA: An Advanced Best Estimate

  • * * *** *-. : Computing.Program for PWR LO'CA Analysis, Vol. 1, LA-7777-MS*,
    • --.:*:- **,.NUREG/CR-0665 (April 1979) *. *.

-:~;; ~t. 6". LOFT Engineered Safety Systems InvestigaHons, ID0-17258 (Aprii 1969).'. .J. H. Linebarger, D. L. Batt, and V.J. Berta, LOFT 'Isothermal and Nucl e'ar Experiment Results, presented at the 14th Ititetsoci ety Energy

    • ~ ':..

-c.* Cohv~rs-fcfrf Engf r'lffifring" conferen*ce,. Boston*, Mass~, (August 6-1 l,.1979). ~~. '.. ~.. ',.' ' -*~ 18~-. [)~ -~* -~.e.ed~r, Slowdown Hydraulic Influence on* Core Thermal Response ~.in LOFT Nuclear Experiment L2-3,

  • presented* *at the. ANS 1979 Winter*

_.* Meetfng, San Frantisco, CA., (November 11-16, 1979). , 19 *. C_. S. Ols~n; Zf rc~l?Y Cladding Col lalse ~Under. Off-Normal Temperature and Pressure Conditions*,* TREE-NUREG-.239 (Apr1 l 1978). 20 *. M. L., Russel, LOFT Iilstrumented_.f.uel Design a*nd Ope*rating .*. Exper*ie*nce~* *~resented* at the 14th' I,ntersoeiety Energy Conversion

  • !ngfoeerfng onference, Boston, Mass., Aug 6-11, 1979..
  • ,
  • 2l.

D. L. Batt, Downco.me.r Fluid. Phenomena in LOFT Noririuclear lOCEs, .NUREG/CR-0268, TREE 1139 {August 1978).

22. P._ l<ehler, Measurement *o_f the.Emergency Core -Coolant Bypass Flow
  • .*on the LOFT Reactor, NUREG/CR-0208, ANL-CT-78-37 (July 1978).
23.

L. 8. Thompson, Y. Y. Hsu, :"Minutes of the Denve*r* Meeting oil Rew.et

  • Phenomena," Aprf 1 11-12, 1979, USN RC 1 etter.
24.

E. L Tolman, D~ *A~.Nfebruegge,.an~ P~,G. Prassinos*, Nuclear Fuel

  • .'Rod. Behavior Durfitg LOFT Experiment L2-2, International

.... *Colloquium On Irradfatf on Tests for Reactor Safety Programs,

  • Pet ten, The Nether 1 ands, June 25-28, 1979.
i.

I ! I< . I i \\. I i t.

    • ~ -;'.

. ~ 7 ' 25 *. *J1.* *.A.* ~~ng_~rm~n ~.* c6hsi de~ati.~n. Of.S.caJ i ng.Effects in* t.~e.Loft:**Reactor.

  • .*syst~ During* a_200:%:co1d:1Le~~Break*Test*,. *SEMI-fR..;gps. (May J97~).:.*.*
26. *. G. ~k Rc)gers, ;, Analysis :of -Scaling -~he S~m{sc~l e'<Mob 3 System to a *.*

,. t

  • ~.Pressurfied Water* *Reactor~~- :**sEMI~ TR~oos, (May 1979) *. *

.. _M. A~ lang~rfllan,j)~.s~ chJ,.~-Ef.fect* of -Scaling Comprg~i_s~s Between*.. :_

  • Hq

. * :.Jemistale MOD. 1: i;"nd *1 OET 'D*irintj large* Bteak [oSS-Of.;cooJ apt Experiments,

  • -sEMI.;.TR-Oll (July 1979)~_-:,*_
    • _¢.ombusticm Engi.need.ng;_ Be'st *:*Esti~ate Pre~Test Analysis of LOFT
    • Test L.2~3., LD-79-029. (May :1979).:-

~ ~ . J. c.* -~~1 ls: et _~l~:-*Pretest: RETAAN AnalYs1s for LOFT.Test L2*3

    • (Standard Problem #10), ITl"".I-4016.-(May),1979).*.*

30~

  • _E. *J~ Kee and W. H~ Gr.~sh,' Be:st:istimate_ Predict1.on.for LOFT
  • .,,. Nucle_ar<Experifoent l2~3; E,P-L2*3:* (Apri 1., 1979) *. * : ".
  • .:... 31~ ~. c.: Peterson and* K~ A., J;illiams*, ~TRAd,i>1A Pretest.-~redict1.or1 6'f.
    • .. J\\**,: LO.FtJ*iuc.lear *rest L2.::3, fos idarilos_ Scfen_t1fic Laboratory Report
,,. LA-UR-79-1134 (May 1979).

. * *.. *32~:* Douglas *L~ Reede:r~ uick"."Lhok Re. ort on LOFT Nuclear Ex* ertment,..

: "*t2...;3, supplement 1, EG G~ ! Aug. 1979

-.<33~,P.. H~ll,_A Study.of CrtticaJ.f'low Predict*1ons for SemiscaleMOD-1° : , *}.**: *, Loss.:.Of.;.Cooni:nt. Accident Experiments, JREE-.NUREG-lo06' (Decem_be~,l 976) *~ ii. . *.; <3*4 *. E~.. J. Kee, J.... R~ W,,ite-,.* RElAP4/MOD6 Predictions Comparisons with LOFT LOCE l2-2 Dat'a9. LTR 20.:100 (May 1979) * <,.-35. J. R. White, W.. H.. Grush, t.. D. -Keeler~. Prel:imina.r>i_"Posttes*t *An.alySis ": -, :;... of.LOFT.Loss-of-Coolant Experiment t2.. 2~ i-rR *20..:1-03 (June 1979.). l. ' ~::.. 36. c~ o. Kec}er, J *. R~ Whi1;~*,.i'. R~L,A~4/MQD6 Ptediction:s Comparisons with . :-'.'.' LOFT LOCE L2-3 Data,: LTR* 20!!"104 (August 1979) *. *..

  • ,. 3i *. R~ G. l:f~nson; Quic_k Look RE!Port.Semiscale MOD-3 Test s.:..07-1 Base Line
  • ** _.. ~ Test se*ties,.Report. No.

WR::-S.~ts-ol 3 (July 1978). r . ~,.

-~**.*--- - *"" ~ L" I l. . 3a. G~. D *. McPhers*on;* summary of Jo-1nt Semisc~1e ~*nd LOFT Review Group .,*meetfng (NRC members only) to dfScfrss'_small. bre*at* tests*,- held in "Bethesda, Ju_ly 25, 1979. *

39.. G. D. McP,herson, *sunima*ry of NRC/Ve*ndo*r meeting to* *d1 scuss small bteak tests, July 24, 1979.

4p~;>. Minutes of. LOFl Revtew _Meeting. he 1 d *tn Idaho Fa 11 s, June 15, 1979.

  • .* * *.., fleld' in: Bethesda, July 25, 1979.

~-..

H. R. Denton - 14.. 7.0 COORDINATION CONTACT\\,, \\ \\ _,,.,,,,/' For coordination of any" further evaluation of these -results and for discussion and future experimentss contact Dr. G.-t:lonald McPherson LOFT Program Manager. RESs Telephone 427-4437. Distribution: Subj Circ

  • Chron Branch R/F **

Slevine JTLarkins. * *

  • TEMurley LSTong CEJohnson GDMcPherson RiF GDMcPherson NRC Form 3188 (4-79) NRCM 0240

~ ~ \\ \\ \\ \\ \\ \\ Saul Lev1net Director \\Office of Nuclear Regulatory Research \\ \\ \\ '\\ \\ \\\\ \\ \\ \\ \\ \\ \\ \\ \\ \\.*

  • u.s. C.OVERNMENT PRINTING OFFICE: 1979 -

2B9-37t

H. 7.0 COORDINATION CONTACT For coordination of any further evaluation of these results and for discussion and future experiments, contact Dr. G. Donald McPherson LOFT Program Manager, RES, Telephone 427-4437. Di stri buti on: ~ubj Circ Chron Branch R/F SLevine JTLa rki ns TEMurley LSTong CEJohnson GDMcPherson R/F GDMcPherson NRr'. Fnrm 11RR 14-7'll NRCM 0?40 Original Signed By ~ul Levine i,!:....... ***- Saul Levine, Director Office of Nuclear Regulatory Research ,.,,....... ~D...... ~......,. PPIMT!Mt":; nJ"t='lri='*

  • Q'J'Q-';'Q~-&n4 ii..}}
Retrieved from "https://kanterella.com/w/index.php?title=ML17263A012&oldid=5106799"