Fast Breeder Reactor (FBR)University of Fukui

Tsuruga NPP (JAPC)

JAEA Tsuruga HQ

Tsuruga PeninsulaFugen (JAEA)

(JAPC)INSS

APWR Site Mihama NPP (KEPCO)

Research Center (JAEA)

Monju (JAEA)

( )

Professor H. MOCHIZUKINuclear Reactor Thermal Hydraulics Division

1

Nuclear Reactor Thermal Hydraulics DivisionResearch Institute of Nuclear Engineering

University of Fukui

Outline University of Fukui

• Pu production and fuel cycle• Pu production and fuel cycle• Characteristics of neutrons• Comparison between LWR and FBR• Physical properties of sodiumPhysical properties of sodium• FBRs in the world

C t f FBR “M j ”• Components of FBR “Monju”

2

FBR and LWRUniversity of Fukui

LWR：235U of 0.7% in the uranium ore is consumed. Uranium 235U will be consumed within 100 years

FBR: Breed nuclear fuel (238U⇒239Pu) We can utilize consumed within 100 years.

CRFuelBlanket fuel

( )nuclear fuel for a couple of thousand years.

238U

239Pu Core is small Large core239Pu

Liquid sodium

Core is small.Temp. is more than 500ºC.Atmospheric press re

Temp: ~300ºCHigh-pressure

FBR LWRPu(~20％)+238U(~80％) : MOX Fuel Slightly enriched uranium （ 3～

Atmospheric pressure

Pu( 20％) U( 80％) : MOX Fuel Slightly enriched uranium （ 34％ 235U）

Liquid sodium Coolant waterNon Moderator water

3

Non Moderator waterFast neutron Fission Thermal neutron

Fuel cycleUniversity of Fukui

MineFBR cycle LWR cycle

FBR

Uranium

U3O8

EnrichmentDepleted uranium

FBR fuel

Recovery UEnriched U

UF6

Depleted uranium

Recovery U & Pu

F l f b i ti

Spent fuel

UF6

Recovery U & Pu

Fuel fabrication(U & MOXfuels)

Reprocessing PlantFuel fabrication

Recovery U & Pu

LWRReprocessing Plant

Recovery U & Pu

LWR FuelsSpent fuelHLW

4

Intermediate storageUnderground storage

HLW

Fission in LWR or Graphite reactorUniversity of Fukui

ModeratorControl

moderationWater, Graphite

Fast neutron10,000 km/s1/30 of light speed

2 2 km/s2.2 km/s10,000 km/s

235U has a large fission cross section to a thermal neutron.

5

Some fast neutrons are absorbed in 238U and produce 239Pu.

Neutron irradiation chain of 238UUniversity of Fukui

15

238U 239U 240U452 2.7 22

15

239Np 240Np37

23.5 min 14.1 h

di i t ti Fi i ti

Half-life period

239Pu 240Pu 241Pu 242Pu 243Pu

2.35 d747.4

7.2 min62 min 1012 200

disintegration Fission cross section

239Pu 240Pu 241Pu 242Pu 243Pu270 289 361.5 18.8 90

14.4 y3.1

4.96 h

（n ) reaction241Am 243Am 76.7

242Am639.4

（n,) reaction

6

Microscopic cross section of 235U & 238UUniversity of Fukui

From R A Knief Nuclear Engineering

Easiness of fission

From R A Knief, Nuclear Engineering

0.7％0.7％

99 3％99.3％

Thermal neutronFission cross section is large for thermal neutron

Fast neutronFission cross section is small for fast

7

large for thermal neutron. is small for fast neutron.

Cross section of neutron capture of 238UUniversity of Fukui

8

Number of neutrons produced by one fissionUniversity of Fukui

239PuWhen η is less than 2, breeding is impossiblea

fissi

on

Pu breeding is impossible.

One must be used for fi i d th th

241Pu

oduc

ed b

y

a fission, and the other one should be used for breeding.

utro

ns p

ro

Some of them escape from the reactor.

Thermal neutron Fast neutronber o

f neu

Thermal neutron Fast neutron

Num

9

Energy of neutron (eV)

Characteristics of FBRUniversity of Fukui

• FBR can produce nuclear fuel more thanFBR can produce nuclear fuel more than consumption. Configuration of FBR is different from LWRsdifferent from LWRs.

• Neutrons are not moderated in order to breed nuclear fuel efficientlybreed nuclear fuel efficiently.

• Enrichment of fuel is higher than that of fLWR in order to raise fission probability.

• Fuels should be cooled by good heat y gtransfer coolant (sodium) because power density is high.

10

y g

Comparison of reactor vessel between FBR and LWRUniversity of Fukui

Monju238MWe

Mihama Unit-3238MWe

Reactor vessel is

826MWe

Reactor vessel is thin due to low

t

vessel is thick due to highsystem

pressure

to high system pressure

11

Comparison of fuel arrangementbetween FBR and LWR

University of Fukuibetween FBR and LWR

238U+Pu(20%～30%)Driver fuel

Blanket fuel of 238U is placed in the peripheral, upper and lower region of the core in

Example：238U（96%）＋ 235U（4%）

lower region of the core in order to breed effectively.

•Small core•Short fuel

•Large core•Long fuelShort fuel

•Small diameter fuel

•Long fuel•Large diameter fuel

Enrichment is high in the outer region of the core in order to

12

flatten the power distribution.

Comparison of fuel assemblyUniversity of Fukui

y

Length 4 2m

Length：2.8mFeul elements：162Bl k t ll t

Length：approx. 4m Effective length：Approx. 3.6mWeight：670kg (17×17)

13

Length：4.2mBlanket pellets are inserted in the cladding.

Weight：670kg (17×17)

Comparison of turbine systemsUniversity of Fukui

13MPa483℃

p y

Main steam MSIVLow P turbine

Containment Vessel

0.8MPa

GMSIV

高圧タービン

Low P turbine

Generator

Condenserバイパス弁

DB

6.4MPa278℃Condensate pump

Control valve

Sea waterA

0.0042MPa at 30℃

Vacuum200℃

Turbine rotor

Low pressure feed-waterheaters

Feed-water pumpHigh pressure feed-waterheaters

15 7MPa

Vacuum 25℃

Feed water heaters

Generator

Control valve

Casing

Cross-over pipe

15.7MPa325℃

Casing

Main steamControl valve

Efficiency: ≈32%

14

Extraction Efficiency: ≈40%y

Rankin CycleUniversity of Fukui

TC

Critical point347.15 ℃22 1MPa

TCritical point647.3 K22.1MPa487℃

B’C’

C

LiquidSuper heated

22.1MPa

B’ C’Liq. Super heated S

280℃328℃ Higher energy

- Receive Q1

- Release Q2

Power output L

AB

DD’E

Saturation curve

Super heated steam

MixtureA

BD’

E

heated S.

Mixture~300K

- Power output L1

- Pump work L2Ｓ0

SA S’C SCＳ

0SA S’C

2

1

)()''(

ASADSAreaiiQBSCSCBBAreaiiQ

ACAD

ACBC

'2

'1

)''()'''(

ASSADAreaiiQBSSCBBAreaiiQ

ACAD

ACBC

2121 QQiiiiLL ABDC )''(2121 CDACABBAreaQQLL

F

21''21 QQiiiiLL ABDC )'''(2121 ADCABBAreaQQLL

L

15

)''(11 BSCSCBBAreaQQ ACF )'''(11 BSSCBBAreaQQ AC

L

FBR & LWRUniversity of Fukui

FBR LWRNeutron life time 10-7 seconds 10-5 secondsRatio of delayed neutron 0.34～0.37% 0.55～0.7%Mean free path long shortCoolant Sodium (low corrosive) Water (high corrosive)Fuel UO2,, PuO2 (Enrichment ～

20%）UO2 (Enrichment 3～4%）%） %）

Cladding S.S. ZircaloyDia. of fuel pellet 4～6mm Approx. 1cmOutlet coolant temperature

500～550℃ 280～320℃

Temperature difference 130～150℃ 15℃（B)～35℃（P)Temperature difference 130 150℃ 15℃（B) 35℃（P)System pressure Atmospheric 7MPa（B)、15MPa（P)

Power density Approx. 300kW/l Approx. 90kW/l

16

Burn-up 100,000MWd/t 30,000～60,000MWd/tEfficiency Approx. 40% Approx. 32%

Characteristics of sodiumUniversity of Fukui

◆ Sodium : alkali metal which is soft and has metallic color.Weight of sodium : 0 97 times of water at 20 ºCWeight of sodium : 0.97 times of water at 20 ºC.◆Melting point : 98ºC（97.8 ºC ）.

◆Boiling point : 881.5ºC at atmospheric pressure.g p p p

Sodium is lighter than water Cut by a knife easily Liquid sodium

17

Sodium is lighter than water. Cut by a knife easily Liquid sodium

Reaction of sodium with water and airUniversity of Fukui

◆When sodium reacts with water, hydrogen gas and NaOH are produced.2Na + 2H O → 2NaOH+ H （Hydrogen）＋Heat2Na + 2H2O → 2NaOH+ H2（Hydrogen）＋Heat

Therefore, sodium must be separated from water.

◆Leak speed of sodium is slow due to atmospheric system pressure◆Leak speed of sodium is slow due to atmospheric system pressure. However, sodium reacts with air as shown in photos, and produces a lot of white alkali aerosol.

18

Blow-down of high-pressure and high-temperature coolant

University of Fukui

•Blow-down: Discharge of high-temperature and high-pressure light water

•ECC water injection in order to cool down the heat-up fuel

•Even a small amount of steam leak, a jet is very dangerous. This is a different point compared to a leak of sodium.

9 Aug 2004 at Mihama NPP,5 people were5 people were killed and 6 were seriously i j d

19

injured.

Sodium leak from secondary system on 8 Dec. 1995University of Fukui

Leak location IHX Reactor

EvaporatorSuper heater

Air coolerDebris of sodium from a broken thermocouple

20

Pump for secondary systemwell

Reason of superiority of Na among liquid metalNa K NaK Li Pb Bi Pb/Bi Hg

University of Fukui(70/30) (eutectic)

Melting point(℃) 97.5 62.3 40 186 327.4 271.3 125 -38.9

Boiling point(℃) 881 758 825 1317 1737 1477 1670 357Boiling point(℃) 881 758 825 1317 1737 1477 1670 357

Vapor pressure(600℃)(mmHg) 26 128 5×10-2 3×10-4 6×10-4 22(atm)Neutron absorption cross section

Thermal neutron (barns) 0.505 2.07 71 0.17 0.034 380

Fast neutron (100eV)(mb) 1.1 5(400eV) 1000 4 3 60

Half-life period 15hr. 12.5hr. 0.8sec. 3.3hr. 5days 5.5min.

Thermal conductivity 0.15 0.084 0.07 0.036 0.037 0.02

(600℃)(cal/cm/sec/℃)

Specific heat(600℃)(cal/g/℃) 0 3 0 183 1 0 0 038 0 038 0 03Specific heat(600℃)(cal/g/℃) 0.3 0.183 1.0 0.038 0.038 0.03

Density (600℃)(g/cm3) 0.81 0.7 0.47 10.27 9.66 12.2Heat transport capability 3.4 1.9 1.2 8.8 1.2 1.3 1.2 1.4

(4in.φPipe)(C.H.V./ft2℃sec.)Pumping forth (1/ρ2c3) 47 29.2 78 4.2 178 238 233 169

Price (￡/ft3) 3 42 16 120 40 500 300 730

21

Sodium cooled fast reactorsUniversity of Fukui

Loop type FBR “Monju” Tank type FBR “Phénix”

Secondary sodium

Primarysodium

Primary circulating

pump Air cooler

Turbine Generator

Super heater(SH)

Main motor& Pony motor

（AC)

EvaporatorSea water cooler

CondenserSecondary circulating

pump

Primary Heat Transport System (PHTS)Turbine system

Intermediate Heat Exchanger(IHX)

Core

Evaporator(EV)

Feed water pump

Primary Heat Transport System (PHTS)Secondary Heat Transport System (SHTS)

22

FBR around the worldUniversity of Fukui

BN-600, 800(Belouarsk)Super Phénix (Crays-Malville)

BOR 60

DFR, PFR (Therso)

Joyo (O arai)Monju (Tsuruga)

CEFR(Beijing)

EBR-Ⅱ(Idaho falles)FFTF(Hanford)

Phénix (Marcoule)

( y )

BN-350(Aktau)

BOR-60(Dimitrovgrad)

FBTR, PFBR (Kalpakkam)

Joyo (O-arai)

( )

:Closed：in operation (including outage)

23

First power plant in the world (USA)University of Fukui

( )EBR－I (Experimental Breeder Reactor)Coolant was NaK Four light bulbs were lit up on 20 DecemberCoolant was NaK. Four light bulbs were lit up on 20 December 1951.

24

Donreay Fast Reactor, PFR (UK)University of Fukui

Rating: 60 MWt/15MWeCoolant: Na-K Loops: 24Loops: 24

Prototype Fast Reactor

25

Phénix (France)University of Fukui

Oldest power reactor in France.

Rating: 565MWt/255MWeRating: 565MWt/255MWeCoolant: NaLoops: 3

26

Tank-type FBR（Phénix)University of Fukui

yp )

27

Super-Phénix (France)University of Fukui

p ( )

Electrical power:p1200MWe

D t tiDemonstration plant in France

・Super-Phénix was sacrificed by Prime minister Jopspin on 2 February 1998 in order to have a

28coraboration between Socialist party and green party.

Super-PhénixUniversity of Fukui

Snapshots in side the plant were

p

the plant were allowed after the workshop at SPX. This might be theThis might be the first and the last chance.

29

FBTR (India)University of Fukui

40 MWt /13.2 MWeFuelFuel

Mark I ( 25 Nos.) 70% PuC + 30% UCMark II ( 13 Nos.) 55% PuC + 45% UCPFBR t t SA 29% P O 71% UO

30

PFBR test SA 29% PuO2 + 71% UO2 From IAEA-TECDOC-1531

PFBR (India)University of Fukui

( )01 Main Vessel02 Core Support Structure03 Core Catcher04 Grid Plate05 Core05 Core06 Inner Vessel07 Roof Slab08 Large Rotating Plug09 Small Rotating Plug10 C t l Pl10 Control Plug11 CSRDM / DSRDM12 Transfer Arm13 Intermediate Heat

Exchanger14 Primary Sodium Pump

31

14 Primary Sodium Pump15 Safety Vessel16 Reactor Vault

PFBR in 2008University of Fukui

32

BN600 (Russia)University of Fukui

Beloyarsk NPP is close to Ekaterinburg.

Sit f BN800 BN600

Pressure tube type reactor

Site for BN800 BN600

33

BN600University of Fukui

Modular type steam generatorIrradiation of vibro-pack fuel (Dismantled From IAEA-TECDOC-1531

34

p (War head was used.)

From IAEA TECDOC 1531

BN600University of Fukui

35From IAEA-TECDOC-1531

BN800 Construction siteUniversity of Fukui

36

CEFR(1/3)University of Fukui

( )

37

CEFR(2/3)University of Fukui

38

CEFR(3/3)University of Fukui

39

Core of “Monju”University of Fukui

40

Fuel subassemblyUniversity of Fukui

• Handling head: for the gripper of refueling machineS d k• Spacer pad: keep clearance to the adjacent wrapper tubewrapper tube

• Wrapper tube: keep flow rate and protect fuelrate and protect fuel subassembly

• Entrance nozzle: adjusting j gflow rate. Many orifices to prevent blockage

Length 4 2m

Length：2.8m

41

Length：4.2m

Shielding plugUniversity of Fukui

H l f t tHole for refueling machine

42

Hole for upper core structureg

UIS and refueling machineUniversity of Fukui

g

43

Arrangement of initial coreUniversity of Fukui

g

Driver fuel subassemblies(fuels for driving the core)

Blanket fuel subassemblies(fuels for breeding)

Inner core PuO 20%Inner coreOuter coreBlanket

Neutron source

PuO2 20%PuO2 25%238U

Neutron sourceCFB

CCFFBB

B4CControl rod

44

Flow distribution mechanismUniversity of Fukui

Wrapper tube“Monju” Phénix

Core support platePhénix

Orifices of entrance nozzsle

Slit

nozzsleHigh pressure plenum

Entrance nozzle

Connection pipe

Entrance nozzle

High pressure plenum

45

Low pressure plenumLow pressure plenum

Fuel subassembly of Fermi reactorUniversity of Fukui

A fuel melt accident occurred in October 1966 A part of ain October 1966. A part of a fuel structure fell down at the inlet of the fuel assembly and yblocked the entrance.

Orifices were provided in d t t t t lorder to prevent total

blockage. This is a lesson learned from the accidentlearned from the accident.

46

Piping of primary heat transport systemUniversity of Fukui

Piping is winding in order to absorb stress due to elongation caused by high temperature coolant flow.

47

Intermediate heat exchangerUniversity of Fukui

gInlet of secondary sideOutlet of secondary side

Primary Secondary

Fl t 5120t/h 3730t/hFlowrate 5120t/h 3730t/hInlet temp. 529℃ 325℃

Outlet temp 397℃ 505℃Outlet temp. 397℃ 505℃

Configuration of heat

OD 21.7mm, thickness:1.2mm,

Approx. 6mApprox.12m

transfer tube,

length:6.07mNumber of HT tubes

3294Inlet of primary side

HT tubesRating 238MWHeight 12 1m O tl t f i id

48

Height 12.1m Outlet of primary side

Heat transfer in IHXUniversity of Fukui

100Inlet of secondary sideOutlet of secondary side

10 [1] Seban & Shimazaki

(Nu=5+0.025Pe0.8)[1]

[3]

1 Nu(1) 50MWSG

Nu

(Nu 5 0.025Pe )

[2] Martinelli & Lyon

(Nu=7+0.025Pe0.8)[3] Lubarsky & Kaufman (Nu=0.625Pe0.4)

[1]

Approx. 6mApprox.12m

0 1

Nu(1) JoyoNu(1) MonjuNu(2) 50MWSGNu(2) JoyoNu(2) MonjuSeban-Shimazaki

Inlet of primary side

0.11 10 100 1000 104 105

Pe Outlet of primary side

49

CFD analysis of IHXUniversity of Fukui

yRectifying mechanism

Small holes more than 13000 are meshed at present.

Inlet window

Inlet windows

p

Plate

#1

#2 Rectifying plateSmall holes

Nozzle #3

#4

#5

Inletwindow

Rectifying plate holes

小孔#5

#6

#7 Plates

Inlet of primary sodium

Outlet of primary

(7)

Outleti d

Bank of heat transfer tubes

Shell

50

primary sodium window

Analysis using 60°sector modelUniversity of Fukui

①

②

③

y gHeat transfer tubes

Secondary outletPlate

10% flowrate

④

⑤

⑥

#1

#2

Primaryinlet

Inlet window #3

#4

#50.1

Velocity480

Temp.

OutletFlowrateratio

#6

#70 325Outlet

window 1.0

0.5

ratio

Primary

#7 m/s325℃

Secondary

51M. Takano and H. Mochizuki, CFD Flow Pattern Analysis on Primary-side of IHX for Fast Reactors, ICONE-19, 43412, Chiba, Japan (2011).

0.0 outletSecondary inlet

Internals of IHXUniversity of Fukui

52

Primary main pumpUniversity of Fukui

y

Intake pressure should be positive in order tobe positive in order to prevent cavitation.

Liquid surface is formed inside the casing of the pump. Height of the pump is restricted by this surface height. g

53

Primary main pumpUniversity of Fukui

y

Impeller blade

54

Electoro-magnetic pumpUniversity of Fukui

g

Fabrication of a large EM pump is difficult.

If one can fabricate a large EM pump, the location problem willlocation problem will be solved. Maintenance b

55

becomes easy.

Steam generatorUniversity of Fukui

g

140 heat transfer tubes are coiled.

56

140 heat transfer tubes are coiled.

Super heater used at 50MW SG facilityUniversity of Fukui

Sodium flow

Inner ductHelically coiled heatHelically coiled heat transfer tube

Water flow

57

Air cooler for auxiliary systemUniversity of Fukui

Outlet damperDesign: 15MW, Real rating :20MW

Outlet damper(controlled with inlet vanes)

Approx. 30m Heat transfer tubes with fins30m

~4.5m ~5.3m

~6.5m

I l t d

Inlet vanes

Inlet damper

58Blower

H.T. C. of Finned Heat Transfer TubeUniversity of Fukui

ehdN CopperCarbon S.1000

50 MWSG

a

e

kNu Turbulent

ppS. S.

100

MonjuJoyo

Data by Jameson

+10%-10%

10Pr1/

3 Nu/Pr1/3=0.1370Re0.6702

Data by Jameson

Laminar

10

Nu/

P

1+20%

N /P 1/3 9 796 10 -3R 0 9881

0.110 100 1000 104 105

-20%Nu/Pr1/3=9.796 10 3Re0.9881

×

59

10 100 1000 10 10Re

Inter-subassembly Heat Transfer ModelUniversity of Fukui

Sodium flow in subassembly

1 t

1

sgliq

g

kt

hkU

Centerδg

8002505 .e

sgliq

PehdNu

U

TTk-1

Inter-wrapper flow02505

liqPe.

kNu

Tk

Tk＋1

Tk

k: thermal conductivityk: thermal conductivityh: heat transfer coefficient

60

k+1th layer k-1th layerkth layer

Heat Transfer to the Concerned ChannelUniversity of Fukui

j jjjjnj TTUlNQ 6Tn,i

j

Tmj

Layer k+1

To ij

jm

ji,n

jmi

ji,m

jm TTUzlNQ 1

d i l h

Tm

Layer k

To,i

j: concerned axial meshm: concerned channel groupl idth f h l t b

Layer k

l: width of hexagonal wrapper tubezj: length of mesh j

b f b bli fNmn

,i: number of subassemblies of channel group n facing to the face i

f h l61

of channel m

Exit temperature of 3rd Layer SubassemblyUniversity of Fukui

560

SSC-L520

540)

40℃SSC L

500

re (

deg-

C )

ure

(℃)

Measured460

480

empe

ratu

rTe

mpe

ratu

420

440

NETFLOW++ ith ISHT d l

Te T

400

420

0 50 100 150 200 250 300 350 400

NETFLOW++ with ISHT modelNETFLOW++ without ISHT model

62

0 50 100 150 200 250 300 350 400

Time (sec)

Downsizing of FBRUniversity of Fukui

Volume of reactor building= 810 000 m3 810,000 m

Prototype FBR “Monju”

Gen-IV FBR (JSFR)

Prototype FBR MonjuThermal output 714 MWt

Electrical output 280 MWeGen-IV FBR (JSFR)

Thermal output 3570 MWtElectrical output 1500 MWe

63

Combined IHX and pumpUniversity of Fukui

MotorPump support

primary outprimary inprimary in

secondary out BellowsNSSS

DHX

IHX heat transfer t b

DHX

IHX support

Pump can be withdrawn.

64Pump

tubessecondary in

IAEA benchmark problems #1) Natural circulation test at Phenixand #3) LOF&ULOF tests at EBR-II

University of Fukui

IHX Inlet temp. Mochizuki Lab. was only i ti i J dIHX Inlet temp. organization in Japan and

only university in the world who participated in the calculation.

The benchmark

calculation.

1

input deck was created on the basis of plant configuration and

IHX Outlet temp.

0.1

Measured

Calculated

d flo

wra

te (-

)

configuration and fuel patterns of EBR-II. Now this analysis a kind of

Our result is at the midst of the calculation curves

Flow rate change

0.010 200 400 600 800 1000

Nor

mal

ized blind test. However

left result was presented in an international

65

0 200 400 600 800 1000

Time (sec)international conference.

H. Mochizuki, N. Kikuchi and S. Li, Calculation of Natural Convection Test at Phénix using the NETFLOW++ Code, Proceeding of International Congress on Advances in Nuclear Power Plant (ICAPP 2012), Chicago, Paper 12104, USA, (2012-June).

IAEA benchmark problem #2 about thermal stratification in upper plenum of “Monju”

University of Fukuistratification in upper plenum of Monju

Upper instrumental structure TC plug

Inner barrel Reactor vessel

Fuel handling machineFl h l

Inner barrel Reactor vessel

Reactor outlet nozzleFlow holes

S f f

Fl id t bC SA

Surface of upper support plate

Upper core t t

66

Flow guide tubeCore SAstructure

Overall view of the CAD modelUniversity of Fukui

m m4.

38 m

5.30

m

Upper flow-holes(24)

Lower flow-holes(48)( )

67

CAD model around UCSUniversity of Fukui

UISUIS

Control rod

Honeycombstructure

guide tube

Flow guideguide tube

68

Tetrahedral meshes in the plenumUniversity of Fukui

33 illi i d t t h d l h69

33 million prism and tetrahedral meshes

Configuration of the reactor core at the testUniversity of Fukui

g

Inner core 108 Outer core 90

IAEA ClassificationCh. 1-5Ch. 6-8

Blanket 172Neutron shield 324 Neutron source 2Control rod (Coarse) 10Control rod (Fine) 3

Ch.9-11Ch.12,13 and FCCh. NCh. CCh F

70

Control rod (Fine) 3Control rod (Back-up) 6

Ch. FCh. B

Flow-hole configurationUniversity of Fukui

mer：92

mm

Sodium flowdirection

diam

ete

5mm

5mm

5mm

thickness：40mm R20 R20

Inner barrelFlow hole with

40mm

Flow-hole Flow-hole with

R20

71

Flow-hole with straight edge

Flow hole with chamfer

Flow hole with rounded edge

Results with boundary conditions calculated by 1D codeand with rounded edge

University of Fukuig

Mesh configuration for flow-holes with boundary layers0

0 sec 0 secMeasured Computed

-2000

-1000

0 sec601203006001200

0 sec601203006001200

m)

-4000

-3000

Ele

vatio

n (m

m

-6000

-5000

72

360 380 400 420 440 460 480 500-7000

Temperature (oC)

Contour maps from 0 sec to 20 min.University of Fukui

(m/s)1.0

0.5

00

Evolution of velocity distribution in the upper plenum0 300 600 1200 secEvolution of velocity distribution in the upper plenum

(ºC)510

435

360

E l i f di ib i i h l0 300 600 1200 sec

73

Evolution of temperature distribution in the upper plenum