by M. Takahashi1, S. Uchida2, K. Hata3, T. Matsuzawa2, H. Osada2, Y. Kasahara2, Y. Yamada2, N. Sawa2, Y. Okubo2, K. Koyama2,

M. Hirabayashi4, K. Ara4, T. Obara1, and E. Yusibani51Tokyo Institute of Technology （Tokyo Tech.)

2Advanced Reactor Technology Co., Ltd. （ARTECH)3Nuclear Development Corporation (NDC)

4Japan Nuclear Cycle Development Institute (JNC)

PbPb--Bi Cooled Direct Contact Boiling Bi Cooled Direct Contact Boiling Water Small ReactorWater Small Reactor

INES-1, Tokyo, Japan, November 1-4, 2004,

1. Energy park and small reactor2. Motivation3. Project4. Conceptual design of PBWFR 5. Lift pump in chimney6. Removal of Pb-Bi mists and polonium7. Concluding remarks

ContentsContents

Stable FP

Energy Park

Natural U or Th

Actinide

Long Life FP

FPPb, Bi

(Option)

(Leak)

Transmutation StorageSeparation

FP：Fission Products

Energy UtilizationWith Small Reactor

Outside of Park

Toxic sub.IN

Toxic sub.OUT

Energy Park and Small Reactors with Long Life

Long Life Small PFRLong Life Small PFR- Forced Convection- Gas Lift Pump

SelfSelf--controllable controllable NaNa--cooled Small FRcooled Small FR

HTGRHTGR(CANDLE Burning)

COCO22 Gas TurbineGas TurbineReactorReactor(HighEfficiency, LMFR）

Large PFR-Transmutation-CANDLE Burning

Self-controllable Na-cooled Large FR

Nuclear Energy Park

Outside of Park (Site)Production of Electricity, Heat and Hydrogen

CO2 Gas TurbineMedium Size Reactor

Transportationof Reactors

Long Life Small PFRLong Life Small LFR- Forced Convection- Gas Lift Pump

SelfSelf--controllable controllable NaNa--cooled Small FRcooled Small FR

HTGRHTGR(CANDLE Burning)

COCO22 Gas TurbineGas TurbineReactorReactor(HighEfficiency, LMFR）

Large LFR-Transmutation-CANDLE Burning

Self-controllable Na-cooled Large FR

Nuclear Energy Park

Outside of Park (Site)Production of Electricity, Heat and Hydrogen

CO2 Gas TurbineMedium Size Reactor

Transportationof Reactors

Reactors in Park and Sites

Safe Coolant: Inactive with air, water Void reactivity: Negative

Economic Simple or Reduction of material e. g., Elimination of

- Pumps- Steam generators- Intermediate loop

Efficient in uranium utilization Breeding ratio > 1Proliferation resistant Long life core > 10-15 yrs

Requirements of Innovative Small Reactors

Steam(296℃)

Direct contact BoilingGas Lift Pump

Pb-BiControl Rod

Feed Water(220℃)

Core

Direct Contact LFR (PBWR)

proposed by J. Buongiorno, N. E. Todreas, et al., at ANS Winter Meeting, Long Beach, USA, in 1999.

Steam Lift Pump (PBWFR)Φ5.1mx14.5mH

Forced ConvectionΦ5.2mx15.2mH

150MWe 50MWe

Reduction of component materialEconomy

Research Projects for Development of Innovative Nuclear Technologies

by MEXT (FY2002-2004)

Pb-Bi Cooled Direct Contact Boiling Water FR (PBWFR)

1. Conceptual design 2. Pb-Bi-water direct

boiling test3. Test of steam

injection into Pb-Bi/ O-control

4. Corrosion 5. Polonium measure

ThemeTheme

Direct contact boiling/Steam lift pump performance

Core

Steam with Pb-Bi mists

Polonium measure

Corrosion Water injection/

Oxygen control

1) Conceptual designLong life core, void reactivity and specific structural design,Safety evaluation.

2) Material and chemistryControl of oxygen potential in Pb-Bi,Compatibility of core and structural materials with Pb-Bi,Measure of Po transport into steam system.

Challenges of PBWFR Technology

3) HydraulicsLift pump performance,Suppression of carry-over of Pb-Bi mist/aerosol into steam system,Suppression of carry-under of steam bubbles into down-comer,Ultrasonic flow-meter.

4) Thermal effectDirect contact steam generation performance,Flow instability and vapor explosion.

Pb-Bi

Reaction with air, waterOxidationOxygen controlOxygen sensorAerosol

Core designVoid reactivityPo production

Metal solutionDiffusion PenetrationCorrosionMelting point

HydraulicsTransport

ChemicalMolecular

Nuclear

Mass transportTwo-phase voidMistErosion

Phenomena

Conceptual Design of 150MWe PBWFR

Reactor vessel炉心

Chimney

Fuel assembly

Guard vessel

Core

DHX

Supplywater

Steam

Separator/Dryer

CRDM

CRDM penetration

Ring header

Core barrel

Pipe

Pad

620˚CMax. cladding temp.

110 GWd/tBurnup

220 ˚CSupply water temperature

863 t/hSteam flow rate

1.05Breeding Ratio

450 MWtThermal power

310 ˚CCore inlet temp.

460 ˚CCore outlet temp.

15 yrsRefueling interval

296 ˚CSteam temperature

7 MPaSteam pressure

73970 t/hPb-Bi flow rate

Total 121

Control Rod 13

Pb-Bi Shielding 30

Outer Core Fuel Assembly 42

Inner Core Fuel Assembly 36

12

0.3 w/oContents of U235

in core fuel

15.8 w/oOuter zone11.5 w/oInner zonePu

enrichment

NonLower axial30 cmUpper axialNonRadialBlanket100 cmHeight267 cmDiameterCore

Pu-U nitride(N15 100%)

Fuel

Two enriched zones.

Zones

Homogeneous core

TypeCore

Core Design

Maximum linear power

keff

Fuel Assembly

14

Hex. 272.0Hex. 273.0

15.9

271-12.0

5.0

5.9

Fuel 1000Fuel rod 2360

Fuel Assembly 3975

B

B

A

A

Handling head

Wrapper tube

Fuel rods Entrance nozzle Ratch spring

$ 3 (EOL)Core, axial blanket and plenum

$ 7.4 (EOL)CoreVoid reactivity

>1.05Breeding ratio

1.5 %dk/kk’/15 yrsBurn-up reactivity loss

Breeding ratio

Fuel Assembly

16

272.0 mmFace distance of wrapper tube 15.9 mmPitch of rod arrangement12.0 mmOuter diameter of cladding 271Number of rods 80 %Pellet smear densityGrid spacerSpacer typeDuct typeType

0.04MPaFriction pressure drop in fuel bundle46.1 %coolant

14.1 %structure

39.8 %FuelVolumetric fraction 275 mmPitch of assembly arrangement

Additional Consideration Additional Consideration for Low Void Reactivity Corefor Low Void Reactivity Core

●Safety design demands negative void reactivity for the case of core and upper plenum region voided from considerations of core void pattern of PBWFR.

●Void reactivity (core +upper plenum) of core mentioned above is +3$.

●Considerations of core specification adequate for safety demands have been performed by core height adjustment with same core layout.

RelationRelation of Core Height and of Core Height and Coolant Void ReactivityCoolant Void Reactivity

-15.00

-10.00

-5.00

0.00

5.00

10.00

60 70 80 90 100 110

Core Height　(cm)

Coolant Void Reactivity（＄）

Core

Core+ Lower Blanket+ Upper Plenum

Core+ Upper Plenum

EOL(10years) Vf = 39.8%

Vioded Region

75

Specification of Low Void Core

-5.33.0Void Reactivity(Core+Upper Plenum) ($)

5.67.4Void Reactivity(Core) ($)1.171.122Breeding Ratio (-)0.91.53Burn up Reactivity Loss (%ΔK/kk’)

3,2053,625Assembly Length (mm)331271Pin Number per Assembly (-)15.215.9Fuel Pin Pitch (mm)1212Fuel Pin Diameter (mm)

278267Core Equivalent Diameter (cm)75100Core Height (cm)1015Core Residence Time (years)

Low Void Reactivity Core

Reference CoreItem

15

Structure in Reactor Vessel20

4230

3500

5550

2000

427 5 3

625

2050

355040304440

3380

Chimney

Inner cylinder

Water pipe

Water supply header

Core barrel

Fuel assembly

Reactor vessel

33804440

5140

Core barrel

Inner cylinder

Reactor vessel

Guard vessel

DHX

Reactor Structure

Separatorand dryer

Support of vesselat gravity center

Guard vessel

Exchange of whole core

Upper CRDM

Core Support Structure

Core Support Structures and Core BarrelHung from upper flangein order to pull up when refuelingSupported horizontallyby earthquake-proof pads.

Control Rod Guide TubesGuide Control Rodsfrom Head Plate to CorePenetrate Upper Structures, such as Dryer, Separator and Chimney.Supported by penetrations

(CRGTs maintain CR insertion anytime)

111

111

11

111

11

1111

1

22

22222

22

22

22222

22

33

333

33

33

33

333

33

33

45

54

4554

45

54 4

55

4

4554

45

54

Flow AllocationFlow Allocation

Inner Core: 1,2

Outer Core : 3,4,5

10

Power of Fuel Rod and Max. Cladding Temperature

5

4

3

2

1

Region

12

12

18

18

18

Assemblies

527585619T18.423.226.1P225510565619T18.523.528.4P247563608619T24.929.230.3P264Outer

core

619579536T28.724.920.6P249618571496T31.126.218.4P272Inner

core

FinalMiddleInitialFlow rate(kg/s)

P: Power of fuel rod (kW), T: Cladding temperature (˚C); Initial: 0 days, Middle: 2737 days, Final: 5475 days

Plant System

RVACS

C/V

Separator/dryer

PRACS

Water supply

G/V

R/VCore

Pump

Heater

HP turbine

H2supply

Filter

LP turbine

GeneratorPump

Heater

Chimney

C/R DM

T: Temperature (°C)P: Pressure (MPa-G)W: Flow rate (t/h)

Turbine

Generator(150We)

Thermal power450Wt

Heat balance

Decay Heat Removal

Sectors

Water supply headers

Nozzles

Inner headerOuter header

Performance of lift pump in chimneyPerformance of lift pump in chimney

- Uniform distribution of void fraction -High void fraction, i. e.

Low slip ratio of steam velocity to Pb-Bi velocity

Requirement in sector-type chimney

Total lift pump head 0.198MPaChimney height 3,000mmAverage density 3,788kg/m3

（Void fraction 0.645）

Total pressure loss 0.156MPaBundle 0.081MPaAssembly 0.020MPaHD plate 0.029MPaChimney 0.025MPaDown-comer 0.00068MPa

OneOne--dimensional analysis of dimensional analysis of lift pump performancelift pump performance

Balance of head and pressure loss for Pb-Bi circuit

Experiment of Pb-Bi-Water Direct Contact Boiling Two-phase Flow

Dump tank

Condenser

Pump

Cooler

Dryer

Fuel bundle

DirectContactboiling

Pb-Bi

Flowmeter

P

Pb-Bi-Water Direct Contact Boiling Two-phase Flow Test Apparatus

1

2

3

5

6

7

8

4

ヒータピン（φ12×4本）

給水注入管

下降管（内径φ38.4）

下部ﾌﾟﾚﾅﾑ（内径φ97.1）

四角管（内縁33×33）

ﾁﾑﾆｰ管(1)（内径φ30）

ﾁﾑﾆｰ管(2)（内径φ38.4）

鉛ﾋﾞｽﾏｽ液面

上部ﾌﾟﾚﾅﾑ（内径φ283.7）

冷却ｺｲﾙ

9

10

図2 自然循環時の圧力損失計算モデル（鉛ビスマスのみの循環）

Pb-Bi free surface

Square duct

Lower plenum

Chimney (1)Chimney (2)

Heater pin bundle

Water supply

Upper plenumCooler

Downward pipe

Flow model

0102030405060708090

100110

Heater power Water flow rate Pb-Bi flow rateH

eate

r pow

er (k

W)

Wat

er fl

ow ra

te (k

g/h)

Pb-B

i flo

w ra

te (L

/min

)

0 60 120 180 240 300

200

300

400

500

Tem

pera

ture

(℃)

Outlet of heater pins Inlet of heater pins Outlet steam Chimney Injected waterTime (min)

7MPa

0.5 1.0 1.5 2.0

8.0

6.0

4.0

2.0

0.5 1.0 1.5 2.0

8.0

6.0

4.0

2.0

2mm 10mm

Analysis of Pb-Bi-steam flow

Bubble diameter

0.0 0.2 0.4 0.6 0.8 1.0

Void fraction

Pb-Bi-steam 2-d two-phase flow in chimney

Key issues:-Suppression of carry-under of bubbles-Estimate of bubble diameter

Removal of Pb-Bi mists

Dra

100500

500

2000 φ400

φ400

φ300

Dra

Sep

Dryer

Drain

Separator

Pb-Bi free suface

I.D.40

0

I.D.100

Steam flow

Steam flow

Porous plate

Pocket

Steam flow

Dryer

Cyclone separator

Chevron dryer

Drain

Estimate of Pb-Bi mists and Pollonium

1.1×108Bq/sTransport into steam system

1.06×1011Bq/kg

Concentration in Pb-Bi

1.5×1017BqProduction

Requirement 1) Additional precipitation device2) Ceramic coated turbine blades

2.0x10-4% lower than 2.0%-5.0% in LWR

Ratio of mist flowrate to steam flowrate

4.8x10-4 kg/s or 15.2 t/y

Flow rate

Separator 95.5%, Dryer 2.6%

Removal efficiency

Mist flow rate Polonium

Steam flow in dryer

Flow velocity distribution [m/s]

Flow velocity vector

Droplet measurement and Electro-static precipitation

Design consideration is for a representative PBWFR condition

ESP System

PDA System

Comparison PBWFR Experiment

Velocity 0.6 m/s up to 0.1 m/sMedium Steam Argon GasPressure 7 Mpa 0.1 MpaTemperature 296 C 180 CFlowrate 329400 L/mnt 0.5 - 2 L/mnt

Glass wall

Dump Tank

Level meter tank

Test section

Ar gas injection

39

A design concept of PBWFR has been formulated with design parameters identified, and will be modified by the results of the following studies:

・ Two-phase flow test in the chimneyfor structure design of chimney with gas lift pump,

• Pb-Bi droplet removal testfor the reduction of carry-over and Po transport rate into steam system,

• Pb-Bi-water direct contact boiling testfor stable boiling and Pb-Bi circulation under

practical conditions,• Corrosion/steam injection tests

for corrosion-resistant steels, oxygen control/measurement method and the other Pb-Bi technology.

Concluding remarks