1

University of Fukui

Fast Breeder Reactor (FBR)

Tsuruga PeninsulaFugen (JAEA)

Tsuruga NPP (JAPC)

Research Center (JAEA)

INSS

JAEA Tsuruga HQ

APWR Site

Monju (JAEA)

Mihama NPP (KEPCO)

Professor H. MOCHIZUKINuclear Reactor Thermal Hydraulics Division

Research Institute of Nuclear Engineering University of Fukui

2

University of Fukui

Outline

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

3

University of Fukui

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

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

4％ 235U）

Liquid sodium Coolant waterNon Moderator waterFast neutron Fission Thermal neutron

CRFuelBlanket fuel

238U

239Pu

Liquid sodium

Core is small.Temp. is more than 500ºC.Atmospheric pressure

Large coreTemp: ~300ºCHigh-pressure

FBR: Breed nuclear fuel (238U⇒239Pu) We can utilize nuclear fuel for a couple of thousand years.

4

University of Fukui

Fuel cycle

Enrichment

LWR

Recovery U & Pu

Fuel fabrication(U & MOXfuels)

Depleted uranium

Mine

Reprocessing Plant

Intermediate storage

Reprocessing Plant

Fuel fabrication

FBR

Spent fuel

Underground storage

FBR fuel

Recovery U & Pu

HLW

Recovery U

LWR FuelsSpent fuelHLW

Enriched U

Uranium

U3O8

UF6

FBR cycle LWR cycle

Recovery U & Pu

Depleted uranium

5

University of Fukui

Fission in LWR or Graphite reactor

ModeratorWater, Graphite

Control

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

2.2 km/s10,000 km/s

235U has a large fission cross section to a thermal neutron.Some fast neutrons are absorbed in 238U and produce 239Pu.

moderation

6

University of FukuiNeutron irradiation chain of 238U

238U 239U 240U

239Np 240Np

239Pu 240Pu 241Pu 242Pu 243Pu

241Am 243Am

452 2.7 22

37

270 289 361.5 18.8 90

76.7

23.5 min

2.35 d747.4

14.1 h

7.2 min62 min 1012 200

14.4 y3.1

4.96 h

15

242Am639.4

disintegration

（n,) reaction

Fission cross section

Half-life period

7

University of Fukui

Microscopic cross section of 235U & 238U

From R A Knief, Nuclear Engineering

Easiness of fission

Thermal neutronFission cross section is large for thermal neutron.

Fast neutronFission cross section is small for fast neutron.

99.3％

0.7％

8

University of Fukui

Cross section of neutron capture of 238U

9

University of Fukui

Number of neutrons produced by one fission

239PuWhen η is less than 2, breeding is impossible.

One must be used for a fission, and the other one should be used for breeding.Some of them escape from the reactor.

241Pu

Thermal neutron Fast neutron

Energy of neutron (eV)

Num

ber o

f neu

trons

pro

duce

d by

a fi

ssio

n

10

University of Fukui

Characteristics of FBR

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

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

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

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

11

University of Fukui

Comparison of reactor vessel between FBR and LWR

Monju238MWe

Reactor vessel is thin due to low system pressure

Mihama Unit-3826MWe

Reactor vessel is thick due to high system pressure

12

University of Fukui

Comparison of fuel arrangementbetween 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 order to breed effectively.

Example：238U（96%）＋ 235U（4%）

Enrichment is high in the outer region of the core in order to flatten the power distribution.

•Small core•Short fuel•Small diameter fuel

•Large core•Long fuel•Large diameter fuel

13

University of Fukui

Comparison of fuel assembly

Length：4.2m

Length：2.8mFeul elements：162Blanket pellets are inserted in the cladding.

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

Upper nozzle

Plug

Fuel pinCladding Pellet

Fuel pin

Lower nozzle Fuel pinSpacer

CR guide tube

CR clusterHandling head

Spacer pad

Spacer pad

Wrapper tube

Fuel element

Spacing wire

Spacer pad

Entrance nozzle

Fuel elementPlug

Cladding

Plenum spring

Upper blanket pellet

Pellet

Lower blanket pelletSpacing wire

Plug

14

University of Fukui

13MPa483℃

Comparison of turbine systems

6.4MPa278℃

200℃

Generator

Casing

Extraction

Main steamControl valve

Casing

Turbine rotorCross-over pipe

G

Main steam MSIV

MSIV

高圧タービン

Low P turbine

Generator

Condenser

Condensate pump

Low pressure feed-waterheaters

Feed-water pump

Containment Vessel

バイパス弁

Control valve

Sea water

D

A

B

High pressure feed-waterheaters

Efficiency: ≈40%Efficiency: ≈32%

Containment vessel

0.0042MPa at 30℃

15.7MPa325℃

Vacuum 25℃

Feed water heaters

FBR0.8MPa

PWR

15

University of Fukui

Rankin Cycle

- Receive Q1

- Release Q2

- Power output L1

- Pump work L2

2121

2

1

)()''(

QQiiiiLLASADSAreaiiQ

BSCSCBBAreaiiQ

ABDC

ACAD

ACBC

)''()''(

1

21

1

21

BSCSCBBAreaCDACABBArea

QQQ

QLL

ACF

T

Ｓ0

AB

B’C’

C

D

SA S’C

D’

SC

ESaturation curve

LiquidSuper heated steam

Mixture

Critical point347.15 ℃22.1MPa

T

Ｓ0

AB

B’ C’

SA S’C

D’E

Liq. Super heated S.

Mixture

Critical point647.3 K22.1MPa

21''21

'2

'1

)''()'''(

QQiiiiLLASSADAreaiiQ

BSSCBBAreaiiQ

ABDC

ACAD

ACBC

)'''()'''(

1

21

1

21

BSSCBBAreaADCABBArea

QQQ

QLL

ACL

280℃328℃

487℃

Higher energy

~300K

16

University of Fukui

FBR & LWRFBR LWR

Neutron 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)System pressure Atmospheric 7MPa（B)、15MPa（P)Power density Approx. 300kW/l Approx. 90kW/lBurn-up 100,000MWd/t 30,000～60,000MWd/tEfficiency Approx. 40% Approx. 32%

17

University of Fukui

◆ Sodium : alkali metal which is soft and has metallic color.Weight of sodium : 0.97 times of water at 20 ºC.◆Melting point : 98ºC（97.8 ºC ）.◆Boiling point : 881.5ºC at atmospheric pressure.

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

Characteristics of sodium

18

University of Fukui

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

Therefore, sodium must be separated from water.◆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.

Reaction of sodium with water and air

19

University of Fukui

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

•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 were killed and 6 were seriously injured.

20

University of Fukui

Sodium leak from secondary system on 8 Dec. 1995

Leak location IHX Reactor

Pump for secondary system

Evaporator

Air cooler

Super heater

Debris of sodium from a broken thermocouple well

21

University of Fukui

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

(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 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 0.03

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

22

University of Fukui

Sodium cooled fast reactorsLoop type FBR “Monju” Tank type FBR “Phénix”

Primary Heat Transport System (PHTS)Turbine system

Secondary sodium

Primarysodium

Intermediate Heat Exchanger(IHX)

Primary circulating

pump

Core

Air cooler（AC)

Evaporator(EV)

Turbine Generator

Feed water pump

Sea water cooler

Condenser

Secondary Heat Transport System (SHTS)

Secondary circulating

pump

Super heater(SH)

Main motor& Pony motor

23

University of Fukui

FBR around the world

BN-600, 800(Belouarsk)

FBTR, PFBR (Kalpakkam)

Joyo (O-arai)Monju (Tsuruga)

CEFR(Beijing)

:Closed：in operation (including outage)

EBR-Ⅱ(Idaho falles)FFTF(Hanford)

Phénix (Marcoule)

Super Phénix (Crays-Malville)

BN-350(Aktau)

BOR-60(Dimitrovgrad)

DFR, PFR (Therso)

24

University of Fukui

First power plant in the world (USA)EBR－I (Experimental Breeder Reactor)Coolant was NaK. Four light bulbs were lit up on 20 December 1951.

25

University of Fukui

Donreay Fast Reactor, PFR (UK)

Prototype Fast Reactor

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

26

University of Fukui

Phénix (France)

Oldest power reactor in France.

Rating: 565MWt/255MWeCoolant: NaLoops: 3

27

University of Fukui

Tank-type FBR（Phénix)

28

University of Fukui

Super-Phénix (France)

・Super-Phénix was sacrificed by Prime minister Jopspin on 2 February 1998 in order to have a coraboration between Socialist party and green party.

Electrical power:1200MWe

Demonstration plant in France

29

University of Fukui

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

Super-Phénix

30

University of Fukui

FBTR (India)

40 MWt /13.2 MWeFuel

Mark I ( 25 Nos.) 70% PuC + 30% UCMark II ( 13 Nos.) 55% PuC + 45% UCPFBR test SA 29% PuO2 + 71% UO2 From IAEA-TECDOC-1531

31

University of Fukui

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

Exchanger14 Primary Sodium Pump15 Safety Vessel16 Reactor Vault

32

University of Fukui

PFBR in 2008

33

University of Fukui

BN600 (Russia)Beloyarsk NPP is close to Ekaterinburg.

Site for BN800 BN600Pressure tube type reactor

34

University of Fukui

BN600

Modular type steam generatorIrradiation of vibro-pack fuel (Dismantled War head was used.)

From IAEA-TECDOC-1531

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University of Fukui

BN600

From IAEA-TECDOC-1531

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University of Fukui

BN800 Construction site

37

University of Fukui

CEFR(1/3)

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University of Fukui

CEFR(2/3)

39

University of Fukui

CEFR(3/3)

40

University of Fukui

Core of “Monju”

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University of Fukui

Fuel subassembly

• Handling head: for the gripper of refueling machine

• Spacer pad: keep clearance to the adjacent wrapper tube

• Wrapper tube: keep flow rate and protect fuel subassembly

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

Length：4.2m

Length：2.8m

42

University of Fukui

Shielding plug

Hole for upper core structureHole for refueling machine

43

University of Fukui

UIS and refueling machine

44

University of Fukui

Arrangement of initial core

Driver fuel subassemblies(fuels for driving the core)

Blanket fuel subassemblies(fuels for breeding)

Inner coreOuter coreBlanket

Neutron sourceCFB

CCFFBB

PuO2 20%PuO2 25%238U

B4CControl rod

45

University of Fukui

Flow distribution mechanismWrapper tube

Connection pipe

Slit

Orifices of entrance nozzsleHigh pressure plenum

Entrance nozzle

Core support plate

“Monju” Phénix

Low pressure plenum

High pressure plenum

Low pressure plenum

46

University of Fukui

Fuel subassembly of Fermi reactorA fuel melt accident occurred in October 1966. A part of a fuel structure fell down at the inlet of the fuel assembly and blocked the entrance.

Orifices were provided in order to prevent total blockage. This is a lesson learned from the accident.

47

University of Fukui

Piping of primary heat transport systemPiping is winding in order to absorb stress due to elongation caused by high temperature coolant flow.

48

University of Fukui

Intermediate heat exchanger

Primary Secondary

Flowrate 5120t/h 3730t/hInlet temp. 529℃ 325℃

Outlet temp. 397℃ 505℃Configuration

of heat transfer tube

OD 21.7mm, thickness:1.2mm,

length:6.07mNumber of HT tubes

3294

Rating 238MWHeight 12.1m

Inlet of primary side

Outlet of primary side

Inlet of secondary sideOutlet of secondary side

Approx. 6mApprox.12m

49

University of Fukui

Heat transfer in IHX

0.1

1

10

100

1 10 100 1000 104 105

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

Nu

Pe

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

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

[1]

[3]

50

University of Fukui

CFD analysis of IHXRectifying mechanism

Inlet window

Nozzle

Inlet windows

Outlet of primary sodium

Plate

#1

#2

#3

#4

#5

#6

#7

Inletwindow

Plates(7)

Outletwindow

Rectifying plate

Bank of heat transfer tubes

Shell

Small holes more than 13000 are meshed at present.

Small holes

小孔Inlet of primary sodium

51

University of Fukui

①

②

③

④

⑤

⑥

Analysis using 60°sector model

Outlet window

Inlet window

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

1.0

0.5

0.0

Flowrateratio

Heat transfer tubes

Primary outlet

Secondary outletPlate

#1

#2

#3

#4

#5

#6

#7

0.65

0m/s

Velocity486

282℃

Temp.

48% flowrate

Primaryinlet

Secondary inlet

52

University of Fukui

Internals of IHX

53

University of Fukui

Primary main pump

Intake pressure should be 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.

54

University of Fukui

Primary main pump

Impeller blade

55

University of Fukui

Electoro-magnetic pump

Fabrication of a large EM pump is difficult.

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

56

University of Fukui

Steam generator

140 heat transfer tubes are coiled.

57

University of Fukui

Super heater used at 50MW SG facility

Sodium flow

Inner ductHelically coiled heat transfer tube

Water flow

58

University of Fukui

Air cooler for auxiliary system

Blower

Outlet damper(controlled with inlet vanes)

Approx. 30m

~4.5m ~5.3m

~6.5m

Design: 15MW, Real rating :20MW

Heat transfer tubes with fins

Inlet vanes

Inlet damper

59

University of Fukui

H.T. C. of Finned Heat Transfer Tube

a

e

khdNu Turbulent

Laminar

CopperCarbon S.

S. S.

0.1

1

10

100

1000

10 100 1000 104 105

50 MWSGMonjuJoyo

Nu/

Pr1/

3

Re

Nu/Pr1/3=0.1370Re0.6702

+20%

-20%

Data by Jameson

+10%-10%

Nu/Pr1/3=9.796 10 -3Re0.9881×

60

University of Fukui

Inter-subassembly Heat Transfer Model

Tk

Tk＋1

k+1th layer

Tk-1

Center

k-1th layer

Tk

kth layer

δg

Sodium flow in subassembly

t

Inter-wrapper flow

k: thermal conductivityh: heat transfer coefficient

8002505

1

.

liq

e

sgliq

g

Pe.khdNu

kt

hkU

61

University of Fukui

j: concerned axial meshm: concerned channel groupl: width of hexagonal wrapper tubezj: length of mesh jNm

n,i: number of subassemblies of

channel group n facing to the face i of channel m

Tn,ij

Tmj

Layer k+1

Layer k

To,ij

Heat Transfer to the Concerned Channel

jm

ji,n

jmi

jni,m

jm TTUzlNQ

6

1

62

University of Fukui

Exit temperature of 3rd Layer Subassembly

SSC-L

Measured

400

420

440

460

480

500

520

540

560

0 50 100 150 200 250 300 350 400

NETFLOW++ with ISHT modelNETFLOW++ without ISHT model

Time (sec)

Tem

pera

ture

( de

g-C

)Te

mpe

ratu

re (℃

)

40℃

63

University of Fukui

Downsizing of FBRVolume of reactor building

= 810,000 m3

Gen-IV FBR (JSFR)Thermal output 3570 MWt

Electrical output 1500 MWe

Prototype FBR “Monju”Thermal output 714 MWt

Electrical output 280 MWe

64

University of Fukui

Combined IHX and pump

Pump

IHX heat transfer tubes

primary outprimary in

secondary in

secondary out

Motor

DHX

Pump support

Bellows

IHX support

NSSS

Pump can be withdrawn.

65

University of Fukui

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

0.01

0.1

1

0 200 400 600 800 1000

Measured

Calculated

Nor

mal

ized

flow

rate

(-)

Time (sec)

The benchmark input deck was created on the basis of plant configuration and fuel patterns of EBR-II. Now this analysis a kind of blind test. However left result was presented in an international conference.

IHX Inlet temp.

IHX Outlet temp.

Mochizuki Lab. was only organization in Japan and only university in the world who participated in the calculation.

Our result is at the midst of the calculation curves

Flow rate change

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).

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University of Fukui

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

Fuel handling machine

Flow guide tube

Reactor outlet nozzle

Upper instrumental structure TC plug

Flow holes

Inner barrel Reactor vessel

Core SA

Surface of upper support plate

Upper core structure

67

University of Fukui

Overall view of the CAD model

4.38

m5.

30 m

Lower flow-holes(48)

Upper flow-holes(24)

68

University of Fukui

CAD model around UCS

Flow guide tube

Honeycombstructure

UIS

Control rodguide tube

Model-1

Model-2 Model-3

69

University of Fukui

Mesh around a flow hole

70

University of FukuiConfiguration of the reactor core at the test

Inner core 108 Outer core 90Blanket 172Neutron shield 324 Neutron source 2Control rod (Coarse) 10Control rod (Fine) 3Control rod (Back-up) 6

IAEA ClassificationCh. 1-5Ch. 6-8Ch.9-11Ch.12,13 and FCCh. NCh. CCh. FCh. B

71

University of Fukui

Contour maps from 0 sec to 20 min.

300 sec 600 sec 1200 sec

0 sec 60 sec 120 sec

0.0 1.0 [m/s] 350 500 [ºC]

72

University of Fukui

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

360 380 400 420 440 460 480 500-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

1000

0 s (Measured)120 s (Measured)300 s (Measured)600 s (Measured)1200 s (Measured)

(SKE)(SKE)(SKE)(SKE)(SKE)

(RKE)(RKE)(RKE)(RKE)(RKE)

Temperature (oC)

Elev

atio

n fro

m th

e su

rface

(mm

)

Time: 0 sec