Coordinating Meeting on R&D forTritium and Safety Issues in Lead-Lithium Breeders

(PbLi-T 2007)

PbLi research activities at Kyoto University

June 11,2007Satoshi Konishi,

Institute of Advanced Energy, Kyoto University

Objective Kyoto University pursues advanced blanket concept based on

LiPb – SiC – He combination to be opearated at 900 degree or above. Research objective includes, -to Establish a possible advanced blanket concept with supporting technology -to Demonstrate the attractiveness of fusion energy with safety and effectiveness i.e. high temperature efficient generation and hydrogen production, minimal waste generation and tritium release, technical feasibility, adoptability to attractive reactor designs.

Activity in Kyoto University

Research Items Current researtch efforts are on the following tasks Conceptual design with neutronics and thermo-hydraulics, MHD LiPb-SiC-hydrogen system study: compatibility, solubility, permeability LiPb technology : Loop experiment, purity control, high temperature handling SiC component development : cooling panel, tubings, fittings and IHX Mockup development : heat transfer, tritium recovery and control

Institute of Advanced Energy, Kyoto University

SiC-LiPb Blanket ConceptSiC-LiPb Blanket ConceptOuter blanket

calculation model•Module box temperature made of the RAFS must keep under 500 ºC.

•Li-Pb outlet temperature target 900 ºC.

•We propose the new model of active cooling in Li-Pb blanket.

•This concept is equipped He coolant channels in SiC/SiC composite and provides more efficient isolation between the RAFS and high temperature Li-Pb.

•We evaluate the feasibility of high temperature blanket in this model.

Li-Pb Flow

3.High temp. outlet (~900ºC)

1.RAFS module box (~500ºC)

2.SiC/SiC active cooling panel

Research Update and Hilights1.Concept verification

- neutronics and heat balance

Typical configurationTypical configuration

Li17-Pb83

FW （ F82H):1.5 [cm]w/cooling channel

SiC/SiC ： 1.5 [cm] w/cooling channel

Neutron

Flux

Plasma

Li-Pb [cm]

（ Net thickness [cm] ）

40.5~55 　（ 45~59.5 ）

6Li [%] 7.4 ~ 90

1MW/m2

One Dimensional Neutron Transport Code (ANISN)

•TBR

•Neutron Shield

•Nuclear Heating

Vacuum vessel

multiplier

0 10 20 30 400.0

0.1

0.2

0.3

0.4

TB

R

Li- Pb thickness [cm]

Total

6Li

7Li

40 42 44 46 48 50 52 540.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

TB

RLi- Pb [cm]層 厚

7.4% 30% 50% 70% 90%

Tritium BreedingTritium Breeding

Relation with Thickness (Li-Pb) and TBR

TBR >= 1.26Li 70% 55cm

6Li 90% 50cm

6Li = 7.4 ～ 90%

•Contribution to 7Li for TBR is less than 5% of all.

•6Li concentration is needed.

•With VV, ca.0.1 increases.

Tritium Breeding Rate

6Li = 7.4%,

Li-Pb thickness [cm]

TB

R

Thickness (Li-Pb) [cm]T

BR

Evaluation of Nuclear HeatingEvaluation of Nuclear Heating

100 102 104 106 108 1100

10

20

30

40

[W

/cm

発熱

量2 ]

[cm]中 心 からの距 離

Photon Neutron Total

F82H SiC/SiCHe Li-Pb

Distribution of nuclear heating

6Li = 90%, TBR = 1.2, Li-Pb = 50cm

Wall thickness [cm]He

at

ge

ne

rati

on

pe

r u

nit

vo

lum

e [

W/c

m3 ]

• Distribution of nuclear heating was calculated.

• Intense nuclear heating by neutron was observed at the front of Li-Pb

• Heat removal must be within a reasonable He flow range.

Heat Transfer AnalysisHeat Transfer Analysis

d1

v

L

Temperature of RAFS side must keep under 500ºC. Temperature of Li-Pb is determined by active cooling of SiC/SiC composite panel with He channels.

Max 500 [ºC]

600 [ºC]

RAFSside~500 [ºC]

Li-Pb

side

SiC/SiC Layer

He

Channel

1. High Temperature Li-Pb

2. Large Nuclear Heating

For example : THe=350 [ºC], VHe = 8 [m/s]

Results of Heat Transfer AnalysisResults of Heat Transfer Analysis

•Max Li-Pb temperature is obtained as a function of He coolant flow speed.He Coolant Temp. = 350 ºC

Relation with Li-Pb side temperature and He velocity 　（ PHe = 8 [MPa] ）

SiC/SiC 1.5 cm, He channel 0.5x0.5cm

600 650 700 750 800 850 9000

20

40

60

80

100

120

140He temp.

He

Flo

w S

peed

[m

/s]

Li- Pb side temperature [deg.C]

300 350 400 450

•900 ºC Li-Pb is possible with moderate He velocity.

Max LiPb temp.

He flow speed

600ºC 11.6 m/s

700ºC 16.5 m/s

800ºC 21.0 m/s

900ºC 25.5 m/s

0 1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

3000

[W/ cm体 積 発 熱 量 3]

[W

/cm

体積

発熱

量3 ]

[cm/ s]流 速

0

200

400

600

800

1000

1200

1400

1600

1800

2000

[℃]出 口 温 度

[℃

]出

口温

度

Outlet Temp. and Velocity of Li-PbOutlet Temp. and Velocity of Li-Pb

Relation with outlet temperature and Li-Pb flow velocity

Net thickness 54.5 cm, Li-Pb thickness 50 cm

6Li = 90%, TBR = 1.2

Li-Pb inlet ： 300ºC

Mean Flow Path 100 cm, Flow path height 10cm

Outlet [deg.]Heat value [J/cm3]

Li-Pb velocity [cm/s]

Out

let

[deg

.]

T

ota

l acc

epte

d he

at

valu

e on

out

let

[J/c

m3]

The MHD pressure drop is considered to be negligible in this condition ( ~1 cm/s).

Outlet temp.

LiPb flow speed

600ºC 1.01 cm/s

700ºC 0.78 cm/s

800ºC 0.68 cm/s

900ºC 0.51 cm/s

•Required Li-Pb velocity is calculated.

Research Update and Hilights2. Tritium Permeation through

Structural materials

The device consists of two lines with high and low pressure divided with disk sample

Permeation of deuterium was measured by using quadrupole mass spectrometer.

Permeation experiments

QMS

IG

RP

TMP

Fig. 1 A schematic diagram of the experimental setup.

manometermanometer

heater

sample

high pressure

line

low pressure

line

D2

Institute of Advanced Energy, Kyoto University

Sample

• Disc samples 20 mm in diameter and 2.79 mm thick were used.

• The sample is fixed between two VCR Couplings with metal gaskets.

• Outside of this test section was vacuum.

After experimentBefore experiment

High pressure lineHigh pressure line Low pressure lineLow pressure line

The method for fixing sample

Hydrogen permeability through SiC

Sample: CVD SiCThickness: 2.79 [mm]Temp: 800 [ºC] Gas: 100% Ｄ 2 1.0x105 [Pa]

0 5 10 1510-9

10-8

10-7

10-6

10-5

time [h]

Pl [

Pa]

CVD 800℃Hexoloy 800℃

Permeation flow rate of CVD was larger than that of Hexoloy by 2 orders

x200

Institute of Advanced Energy, Kyoto University

Temperature dependence of Permeability

Comparative arrhenius plot of the obtained permeability.

hPA

dnK

K: permeabilityn: permeation flow rated: thickness of the samplePh: the pressure of high pressure

line A: geometrical area of the sample

[mol ・ Pa-1/2 ・ s-1 ・ m-1]

0.8 1 1.2 1.410-13

10-12

10-11

10-10

10-9 ℃400500600700800900

1000/T [1000/K]deut

eriu

m p

erm

eabi

lity

, K [

mol

・s-1

・m

-1・

Pa-1

/2]

SUS316CVDHexoloy

Institute of Advanced Energy, Kyoto University

Diffusivity

SUS316:a few secondsCVD: a few minutesHexoloy: a few hours

It is considered that the time taken to start the permeation is related to diffusivity.

The time required to start the detection of permeation gas is…

0.8 1 1.2 1.410-12

10-11

10-10

10-9

10-8

10-7

1000/T [1000/K]

Dif

fusi

vity

[m

2 s-1

]

SUS316CVDHexoloy

Activation energy of the diffusion of Hexoloy is 110 kJ/mol.

Institute of Advanced Energy, Kyoto University

Solubility

Solubility was calculated by permeability and diffusivity.

The solubility in SiC material is ranging 10-4 to 10-3 [mol m-3 Pa-1/2 ] at the temperature above 700 degree C

0.8 1 1.2 1.410-6

10-5

10-4

10-3

10-2

10-1

100

1000/T [1000/K]

solu

bili

ty [

mol

m-3

Pa-1

/2]

SUS316HexoloyCVD

Institute of Advanced Energy, Kyoto University

bccfcc

Institute of Advanced Energy, Kyoto UniversityPermeation in FAFM

0.8 1 1.2 1.4 1.6 1.810 -12

10 -11

10 -10

10 -9

10 -8

1000/T [K -1]

perm

eab

ility

[m

ol P

a-1/2

sec

-1 m

-1]

℃300400500600700800900

0.93mm F82H1.93mm F82HNi

Diffusion in RAFM

Difference understood as the change in crystal structure

Institute of Advanced Energy, Kyoto University

bccfcc

0.8 1 1.2 1.4 1.6 1.810 -9

10 -8

10 -7

10 -6

1000/T [K -1 ]

Diff

usi

on

coeffi

cient

[m

2 sec

-1]

0.93mm F82H1.93mmNi

400500600700800900 ℃

F82H

Research Update and Hilights 3. Compatibility

Compatibility testsKyoto University Institute of Advanced Energy

SiC/SiC composite tube was installed in the LiPb loop Tube section was heated above 600 degree C with LiPb flow Possible corrosion is observed with mucroscopes.

SiC/SiC tube

Test section : heated and cooled

Inner surface of SiC afterexposure

Reaction between LiPb and SiC

Kyoto UniversityKyoto University

Pb mapping

Si の mapping

SiC/SiC composites

LiPb

SiC/SiC did not react with LiPb below 750 degree C.

Corrosion of stainless steelInstitute of Advanced Energy, Kyoto University

Tube surface 、 x100

Inside of tube Welding x100

welding 、 x100

Corroded steelInstitute of Advanced Energy, Kyoto University

(x10000) elements analyses : Cr,Ni missing

X500 SEM elements

Microstructure of ＳｉＣInstitute of Advanced Energy, Kyoto University

SEM observation of SiC : deposit of Cr and Fe found

Research Update and Hilights 4. Chemistry control

- With ion conductor cells

• YSZ (Yttria-stabilized zirconia)–Inside electrode was

made of Pt mesh and Pt paste exposed to air as a standard gas

–Liquid LiPb was used as outside electrode

Solid electrolyte cells for LiPb chemistry control

Ceramics tubes of YSZ for oxygen

Solid electrolyte

Pt paste and mesh

Mulite tube

Thermo-couple Pt wires

EMF

Fig. The cell structure

Pb-17Li

SrCeYbO3 for proton conductivity

Institute of Advanced Energy, Kyoto University

Mass flow controller Gas chromatograph

Potentiostat

Cold trap

Helium gasHelium gas with 10% O2

Pressure gage

Electric heater

electrodes

electrode

YSZ ceramic

Pt paste

Crucible

heat insulation

Solid electrolyte cell

Institute of Advanced Energy, Kyoto UniversityExperiments

- 250

- 200

- 150

- 100

- 50

0200 300 400 500 600 700

measurement oxygen activity in LiPbPeater Hubberstey's report (calculation)

• The cell generates EMF• EMF is converted into

aO2 with Nernst equation

• The theoretical aO2 is calculated from Gibbs free energy equation

• Observed aO2 for LiPb by the EMF agreed well with theoretical value.

)17(/67322882.0ln

ln4}/][{ln 20

2

LiPbatTa

aRTOLiGa

Li

LiO

lna O

2

Oxygen Potential in LiPb

Li⇔Li2O

Pb⇔PbOTemperature[℃]

Measurement Oxygen activity in LiPb

Pb-17Li⇔Pb-17Li-O*

metalinO

airinO

a

P

F

RTE

2

2ln4

*Peter Hubberstey; Pb-17Li and lithium: A thermodynamic rationalisation of their radically different chemistry

*

*

Institute of Advanced Energy, Kyoto University

1.90

1.95

2.00

2.05

2.10

0 2000 4000 6000 8000 10000 120000

2

4

6

8

10

12

EMFOxygen concentration measured at micro GCcaluculated oxygen concentration

Interaction with O2 in cover gas

• Absorption of O2 in LiPb was observed • Absorbed oxygen corresponds to O/Li=0.17.• Increase of oxygen potential in LiPb was detected at the EMF plot

Relationship between EMF and oxygen concentration of cover gas

time [sec]

Oxy

gen

conc

entr

atio

n

[%]

EM

F [V

]

at 450℃

• Cover gas on LiPb is replaced with He-10%O2

Fig. State before and after measurement

0

10

20200 300 400 500 600 700

lna O

2ac

rivity

Metal temperature[℃]

hydrogen activity in LiPb measured withProton conductor cell.

Hydrogen Potential in LiPbInstitute of Advanced Energy, Kyoto University

Research Update and Hilights 5. Loop, Engineering

Development and MHD

Fabrication test of cooling panelKyoto University Institute of Advanced Energy

Fabrication technique for cooling panel and other blanket parts such as FCI and HX are being tested.

Fabrication process15.12 mm

17.89 mm6 mm

15.12 mm

17.89 mm6 mm

SiC cooling panel unit

0.5mm

cutting junction

Institute of Advanced Energy, Kyoto UniversityCooling channel structure

LiPb loop and SiC insertKyoto University Institute of Advanced Energy

SiC/SiC Tube 149mm

SUS316 Tube

流速： 0.7 ～ 1.0 [cm/s]

・ operated at 900 maximum℃

・ Heat transfer and removal requires improvement

Institute of Advanced Energy, Kyoto University

TE43 イメージ炉制御用TE42 予熱器出口TE-B 液温TE32 TS後TE46 CL直前流量

温度[deg C]

流量[L/min]

経過時間[hr]0 5 10 15 20 250

100

200

300

400

500

600

700

800

900

1000

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

LiPb/SiC loop operated at 900C

Glovebox for LiPb experimentKyoto University Institute of Advanced Energy

He-LiPb loop

ＥＭＰ

T

T

Dump tank

T

T

T

hygrometer

cooler

HEATER

GC

断熱材

T

Used forOther project He loop

P

F

F

P

MSB

Zr

GC

T

T

Heater

９ ００℃

９ ００℃

７ ００℃

７ ００℃

～200℃

耐熱合金Testmodule

Vacuum vessel

He loop for LiPb blanketExpansion tank

Original LiPb loop

MHDsection

SiC tube

IHX

• MHD measurement with SiC/LiPb.• Compatibility test at various flow velocity.• Hydrogen/Tritium permeation through composite.• Hydrogen isotherm with LiPb.• Better purity and precise composition with

controlled atmosphere (glovebox).• Instrumentation:EM flowmeter, emf sensor.• Secondary 900C He loop and heat transfer test.• Development of RAFM enclosure , square

SiC duct and flange.• 3-D neutronics and module design.

Kyoto University Institute of Advanced EnergyPlanned test in 2007

• Ultimate goal of this program in Kyoto is to develop a concept of high temperature blanket.

• Small scale blanket module will be demonstrated in 4 years.

• System and component design will be made.• Small neutron source will be used for tritium

transfer experiment.• Possible collaboration on DCLL and further SiC-

LiPb configuration under TBM programs.• Reactor design with near term high temperature

blanket.

Kyoto University Institute of Advanced EnergyLong term plan

• LiPb-SiC blanket concept is now actively studied in Japan at Kyoto University.

• Both experimental and design studies are open for international collaboration.

• Some of the experiments are unique and valuable

for international efforts for liquid blanket

development.

Kyoto University Institute of Advanced EnergyConclusion