W Nudear Fission Reactions. W Compound Nudear Reactions A+8—>2e*— + c+0 Q Direct Reochens A+B—sc+Dd Nuclear Fission +/Fisstom Reaction Nuclear fission is the process in which a heav nudeur splits into eo fragments , cotth the releane of considerable energy and the emission of neutrons and Jovags \ ws osc at on + | BUl—> ater Pt a oO hare , Pris the number of neutrons and is eqpol to 25 GQ-is the releaned energy ard is about 250 Mev gn -is tha projectile called Thermal neutron and its energy is about 0-025 ev oe is heavy muilei set ao target A.B - aw the fissim fragments yin - is yeleaned neutrons called foot neutn amd its ener gj is aloout 4 Mev% Relation behooen Y and y The average number of neutrons both prompt- amd delayed Yeleaned per fission j¢ diven the Symbol PAs the energy of incident aeons vraised , ) increase slowly We define a new parameter 1 which is equal to Aha number of neutrons yelained in fission per neutron alosorbed by a fissile nucleur Since radiatve capture —completen wilh fission is always smaller than D ee On particular, is equal to Y multiplied by the relative probability 6 that an absorption. leads 4o fission 6, qo Sy = yt 5+ 6e. [ 1 & a wey oeW Energy Distribution of fission fragments: qn a fission veacton the Sissioning. muclai almost aluaay s split into +0 fragments of unequal mars Sine momentum munt be conserved in fission, Ake lighter group of fragments receives more. energy han the havier group The distribution of fission. teagments kinetic enevgion dharefore exhibits too peakr an shown in fig-1 amd the higher energy peak, coven ponding fo the lighter fission fragments Lighter a) voup Fragments per unit energy Fission yield -% ° ‘ oa ue bo Ge E in He Jo % WW 130 15d Man namber From the fig 4Re lighter group ith A=95 han an enery of a pproximatel4 lSOMev, Whikk heavier 4reup witte A140 yeesiven alow 68 Nev °Man distribution of fission fragments: fissios Yeil do i ee Ham jumber A Fission ‘is almost always amymmetric so that 4Ra mamer OF the two fragments are substantially alifferent Prpbability of having fission fragments 5f equal man ‘number is veg small From figure fhe most probability of fhe fission. fragments aster the fission reaction are Of man mamber X and 2 And the. probability of producti of qual fission fragments is the Iswont in the figure ply Share oF energy betweon the fission products Vissi fragments 146 Mev, 108 He 89% ~ Neutrons lo Mey 12 ° Se vPrays 5 He F 25), Neutrivo 5 Mev Qo. wv Others 2Mev 3-10 1% B vays Toted 260 ve 10's. trompt P- Tays 3W jrormal Neutrons: A velatively slo moving. neutron whose energy is dighibuted by tba Maxwellian “function. i called tarda meutrons Tdeal thermal neutron energg¢ is 0-025 ev ab the oom temperature (298 Most of Re neutrons yeleared in fission ur ynore than 99% are emitted assentially, at the instant of fissim Thea are called prompt neutron - g Del ayed Neutronss Some neutrons are emitted after foro second of fissim event They came ouk a a result of decay of some fission fragments “Hey are known an delayed neutrons 4 Thermal neutrons (= 0-045" av’) 2 Epithermal neubons (&% 1 kev) 3 Foot reutens E!t2 Mev)MH Fission Yield / Fission product Yield That is tha. percent of the fission. raj ments produced with a given mam rumber Tt fs a funchn of mam number H_The valu of GY ond Me The value» ase plotted in tuble for fission induced ‘f 4hormal neutrons (0:08253 ev) » ws Ss 2 a ou 534. 2499. 2-284 235, a sen 2418 2-066 239 on Far. 297) 2108 24 gy Pt. Lovo 29IF DIYs q Energy vepleared in Nudsar Fission : Ponsrntaige Fissim Fragments 166 Mev ey'/, 2 B- rays 8 Mev an P- rays F Mew 354 Neutrinos 12 Mev Cy Prompt P- vays % Mey ast/ Fission neubens > Mev sf Others 3-10 Mev nen ST 260 Mev ‘607. TotalMh Fssile_nucleté Nudeii that lead to fission Folloring the absorption. of a 2er0 kinetic energy neutron are called fissile nuclew- A. fissimable nuclun thot can be jnduced to fission with "loo eherqy thermal neutrons with a high probability is veffered to ar fissile nuclei Natuce 4 Pal ee oy a Example: C2) ED), SPH . Pu — (sneha Thermal noatrons (0-025 Wav) induce fission corth Re fissile nuclei and 5% ts very large (low) The term fissile vepresents a special cane of the more general term ‘ fissimable E WH Fertile Nuelei : a whisk de Fertile material ig a materiel n abile not itselE Fissionadele by thermal neutrons bul can. be converted ind a fissile “material by neutron absorption amd subsequent? nuelei : 232 234 238. Example wal) gel? oo Onls fart quutrons with energy greeter than. o-F Nev can induce. fission GE is vert small Ce tb) but fission crosssectionq Prompt neutron distributin/ Thermal neutron spectrum Fission neutron energy distribution: The prompt fission nectrons ase emitted corth continuow’ energy speetrum shown in Figure. hich {5 Known an neutron energy spectrum, KE) oe Hen” on em Oe E (Nev) —> The distribution or spectrum is dlefined, bp ite “function X (EB) = 0-459 2'8E sinh 229° where XE) is defined sothab HE)dE % the fur namber/ im of E ond €4d€ at is is normalized, 40-thod, a qOde= 4 @ neutrons with energy betwetn in MeN The function TIE) @ “Tha avarage energy E of Re neutron can be-fourd from, E | E XWde = 1:98 Mev The probable energy corres ponding neutron energy Speehrurn. to the peak 15 0-73 MevNeuttons classification : Average energy 0-025 ex ae salad pop Themed mewbin/ wrpceochbien funchion Enargq of neutron. TRarmal neutrons Z o-t ev Epithermal neutrons > 1 Kev Dntermediate ener neutrons 2 10 Kev Foot neutrons vy. 1 Nev \o yor? o cress Sechien. ove Lev AMeN energy —>MH Nuclear exoss section: Nucleav erozs sectim j$ a quantly, of the probability that an interaction will take “phace betioeen an incident -quetews and a torgeh mentor Geis an area such that the rumber of interachons which ocer in a sample exprsed to a beam of qeatrons 15 equol fo Re product of tre number of- nuclei in He sample and +s number uf neutrons inthe beam -thak would pam through +h area their velocitan coere perpendiculan to it 9+ is denoted by & The unit of nuclear cross-section. is barns 4 barn = [0-24 emt FE Neutron Crass.schion- All neutron e7635 sectimm ane function OF he energt of tha incident nautrons and the notune of the target nuclaur ® Corn pownd Nucleon: (hen The incident neutron is absorbed by th target nuckunr dusying interachom & les edHh Compound Niucleun Fremabion: Most: neutron interachon procerd in two Steps The incident neutron or projectile on striki dhe. target muclkurn first coalesces with it to form a compound — nucleur aes the ararget nucleus is AZ te compound nucleuo ig AY 2 Th compound’ nueleur fren decay inh a number of ways Fay example x JoMev neifron strike a S6Fe mugleur, +e compound muckur is 576 formed and this nucleus mad. decog ba emitting an elarhe or inelaotc neutron > a Pray or two Neutron Tn symbols There processes ore See +n (clastic scattering’) 7 eer vw Cinelashe seattering Neue +P Coodiatva seatering) Fe ton (a2) reaction. vy 56, ol t Fe [ee]® Fission exuss seetion fn vm on, Q al i [0. be) oh os 0 Say ao" Neutron ener - _ tho eva es :MH Neutron Intenactio: Onerof tke, striking. feakiner of. intenachims fat proceed by woo F compound nucleur brmedion is hot thar cross-sections exhibits maxima ot certain sudh maxima ane callea incfdent — neutron | enengien qesonanus The target nuchei have certain excited stokes corresponding to diffensnt configurations of nucleons in 1Re nuclei TE qurns out tint tee incident” mautron amd target nucleus ane mone likely to combine -#F and fies form Campound Nucleus g4 the energy of 462. neutron is such stab Re compownd nucleus 15 Hprodueed in one of Hhase excited staben These resonance shar upIRem in toa cross-sectim §— bocaune it is rneacessanh to form +x Compound nucleus before the inferaction ean proceed Resonances fen neutron (6) Fig: The elastic seottening and Total cross section Jor Ie MH Thelastle Scattering: This proctss does mot oceton un Lem the cnelitrm har sufficdent enangy to place: Be tanget qucew tn te fitse ot Stele As a result cross geetlm is geo up te some +threshad enengy brawenally t64 enengy at cobicks -the first exciteol stake 15 found “deerates wittr imeren sing mam numberAZ a consequence, 5; -i8 monaeno over a langer enerig ‘region for Rei pewier nuclei than for the lighten nucle. The thneshed for inelost'c seattens is 4° Mevifor [2¢ CDhile it ve onla. 44 Kev = 23% AL enengion well above thushold -5 is rough egal to Se’ MB Rodiative Gplune: we can divide Re. radiative capture erocs Section into three enenga region Th fe loo region of mst nuclei, Sy vanio an t/pe joherd E fs dhe neutrm enengy> “Thin muons Bat 5 varia os 1, The law enangy Region fs Byerafore called I%/y Megion Vis die neutron velocity, Tna log-log scale +e loos el veross section appears oo a straight line with a slope of ->+ sab arnt : Newton, eee evs, Fig, Roddetive capfune cress section of AYAbove the % regi ffene fs a region of mesonantis fat occurs ot fin same enengivn an tie resomancer in &: Neat 00 isolated resonance at the enangg Ey Sts. qiven. by Re Breity-Wignen ong-Level formula ie a He 2] an Ea ye Ohene, de is the wavelengths of neutrons woth eneniag Er, gis & constant Known ao statistical factor. Mn ama 14 ane constant -called respectively tha neutron width amd Madiadln coidth and FP a=Pnapg it the told width PF fs the width of Hu mesonanu af one-half its hei Above te resonance regio reahich ends ab about 1 kev in +Pe heavy nuclei and at ineruasingry ight enangios in lighten nuclei Sy drope rapidly and gmat ‘fe vany Smoll vahrer_ Chaw ged. particle, Reactions: The ‘Co Pyne) and offen sharged particle reactions han got certain tnesholds. Reactions ate endothermic Thein erots section’ alto 'rtend to be small even above threshold especially for +he heavier nuclei» Howaven Rue ane some important -exotfenmic reachions in hah nuclei One fh tRese ig log (re) F; cohose cyoss section ts shown im the Follecing figure A L 0, . (sn00b 07+ '28 —> gli the cre o t 01 heey Nesetron, cnanget ©) 64: Te ers sedim fr 6m) FL; reeachim Fram oi ev ty (96 ay . Te will be observed that & is veng lange at loo anergy amd ois + oven saverrol orden of- mregnitucle & energyg Tofet crass cect: ieee ne . ve & = ine ve ‘ WA Fission Gross setin: — eee de The cross sechong -of fissita. for neutron -induced fessPn reagemble nadiative capture cross section in tReirt depencema on Retr fhe. energ¢ of incident neutron Ln Figure he fission cross Sec on > fori 225 ony fRame are frrer distinct reagions AL [eo enertgy OF is & on nearly so; ARis is Soll owed by region oP resonance finaly above the rasonanve rugion 6p is smevth and relling ioamb Ad very tne Brsnid (IPanmed es) ins ml rr Go s000! 0.001 001 out : Neutwn enengy (av) —> Fig: Fission crass section fe 25u Flesion cross section at high anenay Tntermadi att onengit’ eros slim (nesim ePrewmnc) Siete ae ft 7 above Ha nesonene aay 190) use t AME Ceaction -for “ferlile Nioberiol 13% 299 & 239 BO 239 oat (-») oe o3\p —— oy A 232 239 pr 232 as ) e 233 ooh (»») aah Ps Bu BB adawecd Unaninm contains 99-37 2364 and ly, QF 1 235, ong 077 » 235 ftoim. oceun lange fe ‘285 u ME Fision cross section for 2984j° (Fant neutrons): SS 4, hob Asin : Bim P| oT May Neutron erenyy on Muy 3 Fart Newton: A meutron produced ba nucleon fisiat het hos fost Little enemy, tg collision 4 han fp Re tn vexetoy of 0-0 MevHB Caleatole the amount of eres melee in fission. cing alee te eeeee Hise Banking “energy curve, : t I is? A 5 6 = ° 38 ‘6 De Ie Ww EBD Amic mam number A — i fy: Binding enangy cunve ® Firm figure we depict deati dhe bin euungt per pe ee Apon thet for weactmnt 225 an ‘3 oO 93 L aby 5 T 26!" ooo In + PFU cl ce +, fe 430 ° a From binding ener tunve we get thd Nuglide omens pn rnuclson Ya Man num ber (a) m3 93 4 RL gt Mev 140 © : 1 le G4 Mev 25 Fe Mev 235 orTe : ye ounyt rueltored coil! be equivalent” eee Herenee in tea binding enengy between ft and the products " tteny Seton Be rence ABE = : a BE products — BE pea, = (GF per BE «) pea s {(eax8-7) + (tuo x@-4) — (298 x70 Mey = 199:1 Mw W loko ther the lim loho teen the Un shone of the in fissim > Toked- den _thonc_ of fhe eng ele fhe fission fiagments -feke fee Gon shae of the enenae rulsonsd in ficsion — becoune They have. Mea « mans 16g Me if Shared 4 them Hh Fission dain reaction: neuctron In fisstm reaction A ™ mie nucleus bith causes fis ofr, “neutrons is called fiesion colliding wittr an ator S\on and in this reaction eject ona on ™ whida induce Ofhin smuclet to split cain reactions Here ttre product of ore step isa ruattent of tn tfc’ follwing step. 30 tt happen rapidly.WB) Hu bidicaten fact Ki david b The ratio of Hie neutrons numbey: in one ein ‘bow heutevitd ntimber “tn ‘precheding genenation is called ‘Mulltiplicalin factor: K'- ; no ‘of “paws in one geneodion no neutrons. in mraetaling gertnadion K is also called oun factor. ia Tnfinite. mattipticati fretor Th patio of Hie number vf fot reutions” in sucessive genenodions in an infihite sgstem for % given htactor system is called the fafinite inultipliceh’an sretor Mh ig Aenoted oka ie kaa nepf Goins, n= tle mumbey “of fiction neutrons realeased pert neutron absorbed in the fuel. mucleur. _ [3 = dhe. foot fission retac Po- the resonanee escape prepbilty, : fiz the thenmal atitizatin factor;MH Effective mmultiplicotin factor: : : fr an, assembly of finite sdienansins eran —— ane Kett eoil{ be Less than as “facton &?2 Ttghide 5s Aster mined ty the ae leakage Som the system Kigh = Ka i oO loko Lis the neutron’ noi - Lea kaye, probability tomvenienty eqandt Tok. leapage affect into, treo components » a fagh vheutrons , leakage. factor» ‘4 samd a Renmal nectrons leakage, facto. Ayg Le 4 x te —0p u Kap = kale Lag ce. By _Medenaton:_ We miterial whit stow down on “Pranmalized 4a Fotst -remtron, i Knowon an modenato of modanating material, -Evample- ie leght water » H20 heavy water - Dro Giraphit e- eeWE Critic , Supercritical Q Suberitical neactér: « _Crittad » Supercritical & Suberiticad meadlde: Skyy <1 sytem Ish callbd evilizad fisactoh. “the rake meutron oe is ea x pasion fie pee consumption + Y ky>2, the Sct continusn te prodiset’ more feutrons Rane ib - consumer . anid 1S Ren said to be supereritical rivactor- Cenecrgy ettzaned ing chon poagtion Imenases wrth, Aime) $$ KypZ1 fewer ‘imautrons ane produced Han ane consumed such an’ assembly S said fo be suberitical reactr . Gitnans with, tine) B) Derive the a Aor. bs Assume #08 Start with mn, neutrons some of- them will cause fissim wife 8K with a consent indvense in de number of fact neytrons- Letus Jake account “of iS’ small Increase. shy. means, of a cetor & called the fast fission factor “The number of frot neutrons ts mmo increased to” mee Tha enangy of 40x fast neutron is aa reduced stead tg! collisions and Aen enter tote the fea a toy —@ AL +Re Integrals lane covvied gut over. the. same Velume and $0 thei integyale must abo be equal » 6 This is Known, on the. equadion of continuity} neutron “dinsity is indipendidt of time ate eqn tyducn to div? a a Bee go gp as hich “is “Kaown as tee steady Stoke. sqpation OF continuity eB microscopic -eross sectiin o7 macro seop!t cross section = Bacrescopk absoephios cop tedtn “b= neutron foxME Tee Ddiffunion Equstion: | We now substide the ficke law in the continuity eyodion Ficks ‘lassis T= — pv —O and continuity equation is, 20. 6-3 g-av 7 —O on DV beng a 24 _@® there, we have used = av Ta 4Re stationany a ima indepén clont cane a¢ =0 And the, Diffusion agn faker Re frm. Dvwo- =4 +820 This ts ta steady state diffusion equadton 038 com device the tohole 2qn by dD, Yb- Td - £'—O tokens we have. defined v___b : VS — — © 4% diffusion Leng tb “ts called’ He -Aiffucien’ artua. * RB) Soliction to biffusten om _( point source): Consider a point sounte emitting S neutrons . per Second isotropically in an infinite medium Tf fae sounte point is taken fe tbe. 'at the, copter raf a v spherical coordinate systems the fiux deponde only mr: |“The Diffuoten gh take phe form, |) - 1 I aq 4 Se Rg dee sw #0 The appropriodz source condition js obtained bg drawing 4 small Sphere around: he source evnd computing. Afe met number of, mautrons that pass through its sirface. per seeond,- OF tie vadiue of the. sphere Is Y this number fs just Ane te) s0-frot im the limit o vr gon te zero, the “follotstng “anditten is tained: Aim” ws tr) = 7 a a Yoo : To solve. eqn 0 it te conenlent +o imfroduee a new unetion = vd Using this condition. the atflusion eqn becomun Te general Solution ef this eqn is ae hal We dh 4 @ arte -—@© wi "Tova 4 dig "thane fare. . wk oo oe a w eatlt —@ MeWhine A amd € are? unknovon “vonstants~ p muat be. Funiain’ finite, apr becomen inflnite SotRat ¢. must be equ +0 "geno The constant A is fourtd from Re Source. condélion _. -b dd. See 4): Yh Bs amd 40 _s & 4rd a cen v/L fhe flax fs therefore given by = ————— ibe J 8 JEL the Group Diflasim Method ' Sine, meutons ina nuelean reactor har a distribution of enangy it muct be “taken inte account im the diffusion, equation we can davide the energy region into some Jreups F rod Mev Neutron ‘eld semanyy of neutrom— Figea ane ne v Neutrons cou emitted in fie wilt, a eendinu ous -eneng Spectram XE) aw sharon is Figure Re dtetyibudin’ rotibrowdens oa Re, meutrong ane, seattyned in te medium amd atftuse. abot the. system losing -onerga in zlastic..and iqelastic collisions , Tn thermal , rusetors mostof He fist neutrons sucdeed in Slowing agwn all fhe tong to thenmal anergier before pag ane absorbed in ARs Jucl In fast reactors » they s[oro Aown?- aye bess ‘before mduein. fission required +o maintain -the chain reach Garon t py ei i Cee eee P| oy tt 3 rota ty 2 : Et] 2 baveop N= iS rT nop N Fog 2: Erensy qreup fire © greep=diffuales tnlelodion Th the qroup Aiffuolon methid » He entire energy t vegion ts divided into N groups aa. indiaka in Figure 2 . All eG the neutrons goithin each enenyy interval ano lumped togethers amd ffuin diffusion 7 Seatlening os a ns ‘ ‘abs oxphion ant deseribed in terms 6f suitable average diffusion coxfficients amd cross Sechions.Considint for tistanes fhe reutrm in the ath imtenval ave called “git grop tustzond Mosh “energetic. group is for Qe amd Least energetic group ts for gen Ge define tha flux of neutrms in tke git yroup ar tee § ote) ae —~) kine 40) is ‘te energy- dependent “flax:+ Neutrons disa ppean from tha’. qth qreuy bate eh absorption yeactim amd an a presult os sealea colltstms {Rob Case, Hem to .elonye * eninge de ob they mo lengen buing “he th group but ee another group ~The fofal Absorption vate per em> in the gh group in given by Absorption rate “f =) $e) de “Thus we have agen summed up all tte events that oeeun in the gtk group by defining tRe macroscopic yer absorption ¢ 7055 Section: aye coe fe Ee Ag * 3p [=O ¢ ce) de" 1) ‘ » ge The obsorphion yt. ein bes coriithen an. product of the group cross sectim and the group flares c+ Abeonphin ity 9tRe volte af whitch *meutrons Inde. gh, “group aw. ' Siédttensd, “in tReoth grep (5, .orithen ae. “fronton vate Satoh a S ; “ ; S44 oo) an is: Known a's group transfer cross sectton The total rote. at sohidr ,pautrns ae seattened aut of Re a gtOUp per em?/ see is Bani * A ‘ fe 17 SS dy 0 i saa & . — it! ge 969 fea entem’ +the = gee either from sources that emit neutrons directlg “Frrto He qreup Breas A vesult of seatlering from highen groups - “The number’ per m/sec entering Z from 4 thes c hth ‘are 3 b Tran me fm hte =And the total numben scattered into fi fs vobtotned bf summing oven oll” groups thot com seatten inte qt’ grup ‘that all highen enenig. “froupsi» Tot freon nate ole g = EE ae, gy hel EC At . 1 Combining tha term we can orite. ' Dy %bq — = we anew BEA yo g=8 Here bg ig tke grup dafhasion csefficients whidr ¢s given oy. ba = 4 d©) pee) 4e 1 da [re ies 205 f Fey tO ® tohere Zy ts the transport jeross section: ant 4 ts the tet nemben of neukins emithed per em?/see trto He gp: shape of Renctor in Buryiadesh ie Mexegenal ©Wy Recktor Fp b ' Classi fiaadion, of. reactors, according to Rein: uses: © Powers Reactor: " Producti of cleetricity Iso MW « Bamgladorh is planing to bud one with [600 Ney powent from | Russia. @D Researdr Regetor:, Pro dusch'on of neutrons 20 Mw Bangladn h haa got one with SMW power weajhtSitm OSA ep wh @ Breeden: Rucetors Proditctton OF Reactor fuel amd ic efectricitts ~ 400'MW BH Atomle Bomb (tun trin): . ra 7 ee Pakistan» North Korea, Argentina, Lsrach+lean reactor’ Wy Component of a nucteh wa ved ic ton Containment Figr Schematic disgram ofo nucleast reactor» Qeflectors aw made oft grephite Lithium or bergiicamn fo prevenk the leakage of! neutrons: Controt oda ant made Of highly “reutren absmbing material ace boron Cadmium -omd gadolincam (halfnivni). Ctesirt neutron alosorplion eres sectim 15 ‘ver high)HD Light water Penctors (Lwe); IWR is moderated ; peeflected and cooled by Ordimang wot There ors basically to tymer of Lie ners in une - © Pressurized woken Reactors (ewe) ay Boiling. watert Reactor (awe) TE] Pruseurtzccl water Reactors. = tonholad drive assembiy Pressure vessel || Control reed © tontaof ed shroud tube, inlet nozale Zee | ovtiet noodle %25% 290’c 7 HT i Fit assembly align mant- plete i i Fut -assémbi: iI A Core support barrel Cort shroud ~ Core seppert assembly Tnstrumertotin nopztes. view Fig: Cros section of a we, Fudli U0, eramfe madenial Fuels enriched ty 25, upto $7. on Presume: 16M pgStainlen steel container or cladding yodiur [-2em ee Thickneva 200m Fig Single fusl etement of a PWR. Sina water dos not boil ingide te reactor, tHe steam for He turbine murt be produced extennal to the reactor « This is dome bg/ in Steam qoenabr s. tohidh are heat exchangers coith pressurized water on the hot sicle. A typical steam gqensitactor is shown in figure — Steam outlet te fun bite qeneteater moisture sepatiater Swirl vant. moisture sepayator Uppen stull ~ steam drum The bundle Hower shall- 2vapoyater sech' an Ferd water inleb Primo Paton tet Fig: skeom genenator ot a pwR. Primany cooteant ok LepHigh pressure , heated tooleent water from tke factor -enters at the bottom and passes upward amd -then deonward through several “thousand tubes each in the shape of an inverteol u [Ke outert sunfoces of -tRere tubes ‘ane Im veontact with Iswer pressure and ‘cooler feed ,cwoctert returning from the het—watert—trsie -funbind condenser Heat transfered from -tRe. ot unten Insiclethe U- tubes causes tke feed unten fo boil and produce steam. The lowen seetion of a steam generetor where the boiling oceuns §—§ called +Ra evaporation section. fhe wet steam passes upward amd ts drred in several moisture. separater Lange PWR system Lui lize on mony an Sourr Steam gerenaters which Produced steam at about 296 293°C cand 5M Pa “this gives an overall efficiency fh 327. fr a PWR plant: “The fuel sf/ im a POFRA. és slightly enyiched (2°57-) Urantum oliexida V0. whidh is a Black cevamie -matenial tote « amulking point oF 2800 "C : The cladding of a fuel element is cithea Stainless steal of 2in caloy tuber abot 4m longThe completed — prerssurized fuel node vane annanged tm a square lathice structure called a fuel assembly ons fhoon in -figue “The fuel assembly aru {Ren arranged in nean- tgylindricsl array fo form tRe core. the fuel poada in the fuel assembly ane Kept a port by voniaua Spaces - this is important — sine roda, Hat Come Into contac mad. overheat and fulease fi'sston products. eq: Fiat ansermblt of « PWR: © Contra contrel od (Control 4 chamical “shimFET The Boiling Waten Reccter (owe) Cone sh =f one shroud ante bte ——]— steam sepatector Redomten ineh \ n Aen |___— Fiat assembiy Manifoll own éonnen Jet pume = Recirculation VT ih Plenum Fig: Cross seettinn view of a BWR Obview advantage of BWR (s that the steam is formed in the react and goer dinactly to turbine. Storm gensnator fn separate lwp i's not necessand. For this reactor {fe BWR fs said te operate in Oo dAimeet cycle: the pressure in a BWR is “FM pa about ont half the pressure in a PWR Asa mesult the tkicknen vf pressure vessel Ps aho half -that ina PWR $0 cost of pressure vessel Is much less-