1st IAEA workshop on “Challenges for coolants in fast

6 July. 2017

Photo by K.Okano

Satoshi Konishi, Kyoto University

1st IAEA workshop on

“Challenges for coolants in fast spectrum system:

Chemistry and materials”

With contributions by: M. Enoeda, K.Tobita, M.Nakajima, T.Nozawa, H.Tanigawa,

and T.Hirose in QST.

• Fusion Plant is used for the UTILIZATION of HEAT.

The system we develop has a function to

-transfer energy from Nuclear system to Industrial Process.

➡Not coolants, but Heat transfer media is the key.

(perhaps accelerator needs only coolants)

• Considering Intermediate Heat Exchanger and beyond,

technical issues are further demanding

- larger quantity, flow rate and pressure of secondary loop

- contamination and confinement of radionuclides

- cost and use of industrial components, expected life

- occupational safety, environmental emission control, and

public acceptance for normal and hypothetical events.

Introduction Institute of Advanced Energy, Kyoto University

温度熱効率

300

500

800

CO2

D2O

Salt

Liquid Metal(Na)

He

Dry/

Supercritical

steam?

CalderHall

1956

Obninsk

1954

Dresden

1957

EBR1

1951

NPD

1962

FERMI

1963

AGR

1976

MSRE

1965

H2O

Heat transfer media in fission Institute of Advanced Energy, Kyoto University

ShipingPort

1957 Liquid Metal(NaK)

HTTR

1998

Institute of Advanced Energy, Kyoto University

history of fission development

Coolant commissioned

Water(obninsk) 1954

Boiling water 1957

Pressurized water 1957

Heavy water 1962

Carbon dioxide 1956

Molten salt 1965

Liq. Sodium 1951

Helium 1976

Lead Bismuth 1962(?)

Supercritical water ??

Supercritical CO2 ??

Fission reactors have been

developed with dedicated

power application systems.

Fusion can be used with

variety of blanket options

with similar plasma core.

Potential

applications of

better efficiency

technology

No order-

made outfit

available

What is the fusion application, electricity?

To consider the strategy for fusion power options

- coolant compatibility with power application systems

- feasible, available and economical technical processes

for fusion (fission) applications

⇔ There is very limited choice for generation- steam!

(humid, dry and supercritical.)

Brayton cycle or other systems needs dedicated program

In the case of LiPb, He or even water coolant, IHX is the key.

IHX / SG issues - feasible material? (corrosion, reliability and availability)

- tritium permeation

- efficiency

- safety

Objective and scope of study Institute of Advanced Energy, Kyoto University

Energy application issues

○Fusion has no dedicated program for energy application

- coolant compatibility in blanket is studied

- no IHX/SG is available or studied for LiPb, salt, or even He

○Secondary systems (Rankine cycle) available from fission

- if steam generator is made

- Turbines will be driven by tritiated media

○IHX/SG development will be a challenge

- compatibility, chemistry different from blanket (RAFM vs SS)

- preventing tritium permeation while letting heat to go

- efficiency requirements

- safety requirements, expected life longer than blankets

○Industrial generation systems have limited temperature range

Technical issues for system Institute of Advanced Energy, Kyoto University


Generalized model of fusion plant

plasma blanket ＳＧ

turbine

Heat rejection

Tritium recovery

Reactor hall

divertor

Fuel system

building

Tritium removal

Generation process is the dominant release pathway

1 2

3 Tritium

removal

detritiation


Water cooled plant design

direct indirect

Fusion power 2300ＭＷ

Total power 2910ＭＷ

blanket heat 2420ＭＷ

water pressure 25MPa 16.3MPa

in/out temperature 280/500℃ 290/510℃

flow rate 1250kg/s 1256kg/s

divertor heat 490ＭＷ

water pressure 10MPa

in/out temperature 150/200℃ 200/250℃

flow rate 1200kg/s 1120kg/s

efficiency 41.4% 38.5%


blanket

reheater

Heat

exchanger heater

High pressure turbine

Circulation pump

condenser

Generation system design (Direct)

Mid/low pressure turbine

○components

・Industrial components for fire powered station/BWR

：turbine, condenser, circulation pump, reheater..

・turbine/generator available from 1GW class generation

station -cross compound turbine

○design consideration

・divertor heat is used for reheating

・first wall coolant can finally be heated upto supercritical

・commercial regenerative/reheat cycle is adopted

ーno additional confinement assumed for tritiated steam


Direct water cycle(supercritical)

1200MW electricity available at the efficiency 41.4%


Heat balance of direct cycle

blanket reheater turbine

To water detritiation

Steam Generator

Booster pump

feed water heater

（from divertor）

ＣＶＣＳ Circulation pump


Indirect cycle (PWR like)

○components

・Assuming components for PWR and FBR be available

・Dedicated Steam Generator and ＣＶＣＳ

○Design consideration

・Divertor heat is used for reheating at low temperature

・Steam generator different from PWR

－helical coil tubes for FBR

－superheated steam at 25MPa

ーtritium concentration for turbine reduced ~4 order

○efficiency

・1120ＭＷ electricity at 38.5％efficiency


Indirect water cycle

Issue of WCCB→Compatibility of RAFM, F82H and flowing high temperature water

Objective

Corrosion behavior of a reduced activation ferritic/martensitic steel, F82H and effects

of dissolved oxygen (DO) and flow velocity were investigated. ＝＞Determination of required corrosion rate at ITER-WCCB TBM for design

558-598 K / 15.5 MPa

Flow rate: maximum 5 m/s

Fig. 1 Schematic illustration of ITER-TBM

Water cooled ceramic breeder blanket

→primary option for ITER-TBM, DEMO blanket

Tokamak

reactor F82H component

→as thin as possible,

withstand internal pressure

Water compatibility issue

C Si Mn P S Cr W V Ta N B Fe

0.094-0.098 0.10-0.12 0.13 0.004 0.0005 8.07-8.08 1.94-1.97 0.2 0.02 0.0096-0.0097 0.0002 Bal.

Reduced activation ferritic/martensitic steel, F82H

Temperature: 543, 573, 593 K

Pressure: 15 MPa

Dissolved oxygen（DO）: 20 ppb,

1 ppm, 3 ppm, 8 ppm

Time： 28～250 h

Specimen size： f100 mm x 5 mmt

Rotation speed： 0 rpm, 1000 rpm

Test condition

Preparation

Weight measurement

Corrosion test

Macroscopic observation, SEM, XRD, EPMA

Weight measurement

Experimentals

Rotating disk test

Heater

Motor

Specimen

Specimen

T.C

80

37.5

37.5

Cross section of autoclave

Fig. 2 Autoclave for rotating disk corrosion test.

Static 55 rpm(v=0.29 m/s,

r=50 mm)

500 rpm(v=2.6 m/s,

r=50 mm)

1000 rpm(v=5.2 m/s,

r=50 mm)

F82H is susceptible to flow accelerated

corrosion at simulated PWR water condition.

The blocky oxide (magnetite) was not observed

above the rotation speed of 500 rpm.

The weight loss of the rotated disk specimen

was due primarily to continuous dissolution of

Fe ion which caused by dissolution and/or

exfoliation of magnetite particles.

1 mm

Fig. 4 SEM micrographs of the surfaces of static, 55, 500 and 1000 rpm specimens after corrosion test up to 100 h.

Magnetite

The static specimen =>weight gain

The disk specimen => weight loss

Fig. 3 Weight change plotted as a function of rotation speed.

Effect of rotation speed on flow accelerated corrosion

Fig. 5 Weight change obtained from DO 0.02 and 8 mg/L plotted

as a function of time.

Fig. 6 SEM micrographs and XRD patterns of test

specimen after corrosion tests (250 h).

Dominant oxide:

Magnetite

Dominant oxide:

Chromite

Dominant oxide:

Hematite

Dominant oxide:

Hematite

The flow accelerated corrosion (FAC) was negligibly

small by increasing DO contents up to 8 mg/L.

Inhibition of FAC => Formation of hematite as the

diffusion barrier of Fe ion transport.

Effect of DO on flow accelerated corrosion

0.02 mg/L 8 mg/L

◆ ●

0 100 200 300 400 500-1

-0.8

-0.6

-0.4

-0.2

0

0.2

Time (h)

Weig

ht

change (

mg/c

m2)

F82H, 573 K, 15MPa

Open: Static Closed: Rotated disk (1000 rpm)

◇, ◆ ○, ●

Fig. 7 Weight changes plotted as a function of test

temperature. DO 0.02 mg/L => High dissolution of metal ion

DO 8 mg/L => Low dissolution of metal ion

=>The effect of water flow was drastically suppressed by

increasing DO concentration up to 8 mg/L

Effect of temperature on flow accelerated corrosion W

eig

ht

change (

mg/c

m2)

Temperature (K)

• RAFM is generally subject to the water corrosion as it is. One of the

solutions to mitigate the flow accelerated corrosion (FAC) is the anti-

corrosion protective film formation on the surface of RAFM with the

controlled water chemistry.

The considerable weight decrease after the corrosion test in case

of DO of 0.02 mg/L was apparent with increasing rotation speed.

Reduced FAC at DO of 8 mg/L was caused by forming hematite

which acts as the diffusion barrier of Fe ion transport.

Further research…

• Effect of corrosion potential on oxide stability.

• Irradiation effects on F82H, its joints, oxide anti-corrosion film, etc.

(including assessment of the effect of radiolysis of water)

• Effect of DO on environmental strength (SCC, corrosion fatigue)

Optimization of water spec. and materials qualification scheme

Summary of Results of H2O/RAFM

• With current technology(＜700 ℃)

Only Rankine cycle is the possible option.

• Steam generator made of Ni 1 mmt, ~5000m2

Tritium permeation ~1013/Bq day

• He with Brayton cycle needs ＩHX .

permeation is not expected to be prevented.

→Turbine is driven with

tritiated medium

Release only from

Low temperature

HX

Steam generator

For PWR

Power system of ARIES-ST

Brayton cycle with 1173K He Institute of Advanced Energy, Kyoto University

Plate fin structure

100

6 3 3

SiCtube

SiCplate

secondary primary

primary 950℃/400℃ 0~10MPa

secondary 200℃/900℃ 0~10MPa

Heat ~10KW 10 l/s He

Plate ６mm/３mm, 4stage

Size 50mmx100mmx30mm

Tubes ½” equivalent

Test components System design

SiC heat exchanger Institute of Advanced Energy, Kyoto University

secondary（He）temperature primary（LiPb）temperature

Institute of Advanced Energy, Kyoto University Heat transfer analysis

secondary（He）flow primary（LiPb）flow


He-LiPb loop

ＥＭＰ

T

T

Dump tank

T

T

T

hygro

meter

cooler

HEATER

GC

T

Used for

Other project He loop (other project for IHX)

P

F

F

P

MSB

Zr

GC

T

T

Heater

９００℃

９００℃ ７００℃

７００℃

～200℃

Ni alloy

Test

module

Vacuum

vessel

High Temperature He / LiPb loop Expansion

tank

Original

LiPb loop

MHD

section

SiC

tube

IHX

LiPbflow and heat exchange

0

200

400

600

800

1000

1200

1400

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

LiPbflow [L/min]

Exc

hang

ed h

eat

[W]

LiPb: 480C, He: 420C, 500L/min





Heat transfer experiment

1.0E-14

1.0E-13

1.0E-12

1.0E-11

1.0E-10

0.001 0.01 0.1 1 10

トリチウム分圧[Pa]

定常透過フラックス[mol・m

-2・s

-1]

Tritium permeation at 1073K was measured

Institute of Advanced Energy, Kyoto University Tritium permeation

Tritium partial pressure (Pa)

Tritium

perm

eation f

lux

Institute of Advanced Energy, Kyoto University Compatibility of SiC with LiPb

Compatibility of SiC with LiPb measured up to 1173K with

rotating disks

Equipment Temp. Disc rotating speed Density Viscosity

coefficient

Small-scaled RDE 900ºC 200rpm 9171.7kg/m3 1.15657mPa·s

Large-scaled RDE 700ºC 120rpm 9171.7kg/m3 1.15517mPa·s

Institute of Advanced Energy, Kyoto University Compatibility with LiPb

a)Thickness change of reactivelayer against radial direction

10mm from the center 25mm from the centerC

VD

-SiC

(Nonro

tati

ng)

Aft

er 900°C・

1000h

CV

D-S

iC(R

ota

ting)

Aft

er 900°C・

1000h

CV

D-S

iC(R

ota

ting)

Aft

er 900°C・

1800h

20mm from the center 40mm from the center

CV

I-SiC

/SiC

(Rota

ting)

Aft

er 700°C・

1000h・M

atr

ix

CV

I-SiC

/SiC

(Rota

ting)

Aft

er 700°C・

3000h・M

atr

ix

CV

I-SiC

/SiC

(Rota

ting)

Aft

er 700°C・

3000h・Fib

er

(b) Thinning depth change of base-sample against a radial direction


Thickness change of reactive layer against a radial direction


SiO2 (on surface of SiC materials) + 2Li2O (in flowing liquid Pb-Li alloy) = Li4SiO4

(on surface of SiC materials)

SiO2 (on surface of SiC materials) + Li2O (in flowing liquid Pb-Li alloy) = Li2SiO3 (on

surface of SiC materials)

Institute of Advanced Energy, Kyoto University Summary of LiPb/SiC results

・ＳｉＣ reacts with flowing ＬｉＰｂ at 973K and above.

・dependence on flow speed is small and incubation time is

observed.

・reaction is not corrosive and will not affect strength or

electrical conductivity

・additive oxide enhances the reaction, but is not necessary

・reaction is unavoidable if oxygen would not be removed.

After

Before

SiC/SiC composite F82H SUS316

After

Before

SiC/SiC composite F82H SUS316

SiC with

supercritical water

Before the test 5MPa,100h 5MPa,300h

8MPa,100h

8MPa,300h

SiC with supercritical CO2

→corrosion observed →no change observed

Institute of Advanced Energy, Kyoto University Compatibility with other media

Drain/

cooling tower

Stack

/scrubber

Tritium migrates with heat. Blanket concepts have major impacts.

Coolants, heat exchanger, energy conversion…

Fuel cycle

Heat rejection/ Condensor

Heat exchanger

(SG/IHX)

ADS

TRS

Reactor hall Plant

Turbine & Generator/

TRS

Sea Water


Instead of conclusion

Tritium emission from normal operation


Drain/

cooling tower

Stack

/scrubber

Tritium processing with equipment for normal operation will be used.

Emission from Accidental Events

Fuel cycle

Heat rejection/

Condensor

Heat exchanger

(SG/IHX)

ADS

TRS

Reactor hall Plant

Turbine & Generator/

TRS

Sea Water

Heat exchange and tritium flow

breeder coolant Tritium

recovery

IHX Genera-

tion

Detri-

tiation

solid Water

/ He

Isotopic

/chemical

Steam

generator

Rankine Isotopic

WDS

Solid gas chemical Steam

generator

Rankine

Isotopic

WDS

Liquid

metal

metal physical Steam

generator

Rankine

Isotopic

WDS

Liquid

metal

gas chemical g-g IHX

Brayton

metal physical Metal-gas

IHX

Biomass

hybrid Heat transfer media is a possible problem for workers.


breeder

Tritium

recovery

coola

nt

Heat

exchange

Energy

conversion 検討例

Solid + He

sweep water SG Steam turbine SlimCS

Solid + He

sweep He IHX Gas turbine PPCS-B

Liquid metal water SG Steam turbine PPCS-A

Liquid metal He +

LM

IHX,

Recuperator Gas turbine ARIES-ST

Liquid metal IHX Fuel

production GNOME (kyoto)

Liquid metal IHX Gas turbine ARIES-AT

Liquid metal He IHX Gas turbine

Blanket and energy conversion

SlimCS with PWR generation condition

plant

Fuel cycle

Condenser

Steam generator

ADS

TRS

Reactor hallPlant

Turbine & Generator

WDS WDS

Breeding blanket

2.0e12 Bq/s

permeation

1.4e10 Bq/s

Water

Water/

steam He

Steam generator

3.4e8 Bq/s

Environmental emission：2.8e6 Bq/s HTO to air

Coolant to

ocean

Water coolant

With DT<7K,

20 ton/s

Discharged

To the sea

100Bq/kg

?


(tritium production＝2.0e12Bq/s)

WDS capacity： ITER (20L/h) Darlington (360L/h)

WDS Permiation

to coolant

permeation to

2nd coolant

Leak to

waste water

20kg/h 1.4e10Bq/s 1.4e9Bq/s 1.2e7Bq/s

360kg/h 1.4e10Bq/s 3.4e8Bq/s 2.8e6Bq/s

Pipe

thickness

Permeation

to coolant

Concentration

in coolant

Permeation to

2nd coolant

Leak to waste

water

1.5mm 1.4e10Bq/s 1.4e11Bq/kg 3.4e8Bq/s 2.8e6Bq/s

2mm 1.0e10Bq/s 1.0e11Bq/kg 2.9e8Bq/s 2.4e6Bq/s

1.5mm,

TPR=100 1.4e8Bq/s 1.4e9Bq/kg 3.4e7Bq/s 2.8e5Bq/s

Blanket coolant pipes (permeation barrier)

DEMO will require 2 orders larger throughput.

Coolant contamination Institute of Advanced Energy, Kyoto University

In the case of Biomass Hybrid

plasma blanket ＩＨＸ

Tritium

recovery

Reactor hall

divertor

Fuel

cycle

building

detritiation

Use of endothermic reaction does not dump waste heat

Poduct (slightly contaminated) shipped out to wide area

1 2

3

detritiation

Chemical

reactor

Product

fuel

No heat

rejection

Waste

biomass

Product

fuel


Conclusion

• Tritium emission will be controlled by heat transfer media, that

could be a “show stopper” for fusion due to safety,

environment and public acceptance.


• Fusion development will need R&D effort for the use of

blanket coolant.

• Intermediate heat exchanger or steam generator would be the

key component.

• Power application will depend on the industrial technology, if

tritium emission could be controlled.

• WDS will be needed to handle ca. 2 orders of magnitude

larger capacity.

Fusion-biomass hybrid reactor for fuel production

Fusion Biomass Hybrid plant

Rp=5.2m Gasification reactor

Biomass

Fuel

Pn ~1MW/m2

Neutron

wall load

Major radius

Small ≧900oC High temp.

extraction

High efficiency

energy

conversion

PbLi blanket with SiC

cooling panel

IHX


High Plasma Q not required

18 10

10 22

10 21

10 20

10 19

1 10 100

Ｔ（ｋｅｖ）

Break-even

Ｑ＝１，η＝１

Electricity

generation

Ｑ＝20，

ηe＝0.33

biofuel

Ｑ＝５，

ηｆ＝２．７

-0.6

Negative power

ITER

DEMO

Driven and pulsed

operation is acceptable

High temperature blanket

To be developed.

High output temperature is

required for gasification

efficiency is required

Biomass Hybrid Concept

Net

6Pf

Net

8Pf

GNOME


Tritium Balance in plant

Biomass

HEX

Tritium

4.5E - 04

LiPb Pb

Recovery System 1

Tritium Recovery System 2

Reactor Plasma

T

2.3 E - 8

2.3E

2.5 E - 10

4.7E - 04

0.724 m 3 /s 0.652 m 3 /s

Permeation

Recovery

Consumption Blanket

4. 7 E - 04

Generation Permeation IHX

Tritium

4.5E - 04

Pb

Recovery System 1

Tritium Recovery System 2

Reactor Plasma

T T

2.3 E - 8

-08

2.5 E - 10

4.7E - 04

0.724 m 3 /s 0.652 m 3 /s

Permeation

Recovery

Consumption

Stock

2.3 E - 0 5 Stock

Stock

2.3 E - 0 5 Stock

[mol/s] Recovery

Blanket

4. 7 E - 04

Generation Permeation

IHX permeability assumed from SiC data

Reactor leakage assued to be 1%

netTBR 1.05

n

Product

Fuel gas

2.9e3Bq/m3


UNSCEAR 2008report

Tritium emission to the ocean environment

UK

CANADA

Argentina

France

Japan

Spain

Germany

USA

Documents

1st IAEA workshop on “Challenges for coolants in fast