1. High Temperature Blanket and Its Socio-Economic Issues
Institute of Advanced Energy, Kyoto University
High Temperature Blanket and Its
Socio-Economic Issues
Satoshi Konishi
Institute of Advanced Energy, Kyoto University
Contents
- Fast track and Development Strategy in Japan
　- Power plant design
- Hydrogen production
- Safety and environmental impact

2. Fast Track : the next step
Institute of Advanced Energy, Kyoto University
Fast Track : the next step
Fusion study is in the phase to show a concrete plan for Energy.
-Power plant design and strategy following ITER are required.
Common understanding
・Resource constraint (Energy)
・Global warming problem (Environment)
・Growth in developing countries (Economy)
Energy Demonstration in 2030?
Technical feasibility
Combined Demo-Proto steps
Social feasibility
Strategy varies in each Parties due to different social requirements.

3. Fast Track Discussion in Japan
Institute of Advanced Energy, Kyoto University
Fast Track Discussion in Japan
2000
2010
2020
2030
Power
Demo
ITER
TBM
Tokamak
IFMIF
Concept
Design
Const.
Test
BPP
Generation
EPP
module1
module2
High beta, long pulse
KEP
EVEDA
New line
10dpa/y
20dpa/y
RAF
In pile irradiation
Full irrad.
1/2 irrad.
Evolution required
In a same facility
Drawn from Fast track working group in Japan, 2002,Dec.

4. Researchers’ viewpoint
Socio-Economic Aspect of Fusion
Institute of Advanced Energy, Kyoto University
・Future energy must respond to the demand of the society.
・Social and Economical feasibility of fusion depends on
high temperature blanket and its feature.
Fusion
Other Energy
Outcome/benefit
Energy
Supply
Present Programs
Social viewpoint
Damage/cost/
”Externality”
Future
Social
Demand
Government
Public
funding
Socially Required
Government
Outcome
funding
Fusion
Development
Previous Programs
Researchers’ viewpoint
Technically feasible
Generation

5. Power Plant Design Near Future Plants
Institute of Advanced Energy, Kyoto University
Near Future Plants
-Reduced Activation Ferritic steels (RAFs) are expected as
blanket material candidates.
-Considering temperature range for RAFs, 500 C range
is maximum, and desirable for efficiency.
-From the aspect of thermal plant design,
ONLY supercritical water turbine is the available option
From fire-powered plant technology.
-No steam plants available above 650 degree C.

6. Flow diagram of indirect cycle
Institute of Advanced Energy, Kyoto University
Blanket
Reheater
Turbines
Tritiated water
processing
Steam Generator
Booster pump
　Feed water heater
（divertor heat）
CVCS
Feed water pump

7. Thermal plant efficiency
Institute of Advanced Energy, Kyoto University
Direct cycle turbine train generates 1160MW of electricity.
Thermal efficiency is estimated to be 41%.

8. Comparison of Generation Cycles
Institute of Advanced Energy, Kyoto University
　　　　　　　　　　direct　　 indirect He gas
Main steam pressure　 25MPa MPa MPa
Turbine temp ℃ ℃ ℃
Coolant flow rate　　 　1250kg/s kg/s kg/s
Vapor flow rate kg/s kg/s kg/s
Total generation MW MW MW
Thermal efficiency % % %
Technical issues　　 tritium in　 steam expansion
　　　　　　　　　 coolant generator volume
Other thermal Plants:
BWRs – 33% PWRs – 34%
Supercritical Fire – 47%
Combined gas turbine - >60%

9. Findings Institute of Advanced Energy, Kyoto University
-Supercritical water cycles is desirable and possible
(technically difficult).
- No gas turbine system is effective in temperature ~500 C.
- With steam generator, gas cooled is less effective than water.
- Plant design limited above 650 C.
High temperature material does not guarantee economy.
Improvements may be required in the DEMO generation.
Possible Advanced Plant Options
High temperature cycle can be planned with He gas turbine at ~900 C.
Only dual coolant LiPb blanket has possibility for high temperature in ITER/TBM.
At high temperature, use of heat for hydrogen production
may be an attractive choice.

10. Fusion Contribution with hydrogen
Institute of Advanced Energy, Kyoto University 30
actual
estimated
Renewable hydrogen
renewables 20
Gton oil equivalent/year
nuclear
Fusion hydrogen
gas
Fusion electricity
hydro 10
Unconventional gas
oil
Unconventional oil
coal
1900
1950
2000
2050
2100
year

11. Hydrogen Production by Fusion
Institute of Advanced Energy, Kyoto University
Hydrogen Production by Fusion
Fusion can provide both high temperature heat and electricity
- Applicable for most of hydrogen production processes
As Electricity
　-water electrolysis, SPE electrolysis　: renewables, LWR
　-Vapor electrolysis : HTGR
As heat
　 -Steam reforming:HTGR(800C),
-membrane reactor:FBR(600C)
　 -IS process :HTGR(950C)
　-biomass decomposition: HTGR

12. Energy Eficiency Institute of Advanced Energy, Kyoto University
◯amount of produced hydrogen from unit heat
　 ・low temperature（３００℃）generation　　　
→ conventional electrolysis
　 ・high temperature（９００℃）generation
　　　→ vapor electrolysis
　 ・ high temperature（９００℃） → thermochemical production 　
Hydrogen
production
From 3GW heat
electricity
Energy
consumption
efficiency
300C-electrolysis 3 3 % 1 G W 2 8 6
kJ/ m o l 2 5 t / h
900C-electrolysis 5 % 1 . 5 G W 2 3 1
kJ/ m o l 4 4t /h
900C-vapor electrolysis 5 % 1 . 5 G W 1 8 1
kJ/ m o l 5 6t /h ー 6
kJ/ m o l 3 4 0t / h
900C-biomass ー

13. Use of Heat for Hydrogen Production
Institute of Advanced Energy, Kyoto University
◯Processing capacity: 3GWt
　 ・2500t／h waste t of H2
1.3x106 fuel cell vehicles (6kg/day)
or 6.4 GWe (70% fc)
H2 340 t/h
Heat exchange,
Shift reaction
CO2 3.7E+06 kg/h
2500 t/h
biomass
CO 2.4E+06 kg/h
Fusion
Reactor
3ＧＷｔｈ
H2 1.7E+05 kg/h
H2O
Chemical
Reactor
cooler
Steam He
(770 t/h)
Turbine
1.38E+07 kg/h
600℃

14. Hydrogen from biomass and heat
Institute of Advanced Energy, Kyoto University
The experimental results of
the change in carbon
atoms combined in
carbonized gases
[mol.%] 5 10 15 20 25 30 CO 2 CH 4
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030 35 65 85 H
by measurement
by calculation
[cm 3
/min] A
mount of hydrogen
production
[mol]
flow rate st
eam concentration
[%]

15. Fusion safety and environmental impact
Institute of Advanced Energy, Kyoto University E X H A U S T F L N
SOLID WASTE B K R P C M I Y O D
RELEASE W G V i g h t e m p r a u , s o c f y n l v : 1 /
　①Solid Waste
Impact pathway ②Tritium Release from Coolant
③Fuel Processing exhaust

16. Inventory distribution compared with ITER
Institute of Advanced Energy, Kyoto University
OFF-SITE
FUEL
STORAGE
550 g*
FUELING
50 g
ISOTOPE
SEPARATION
　 190 g
PURIFICATION
100 g
EFFLUENT
PROCESSING
～1 g
WATER
DETRITIATION
COOLANT
HOT CELL
500 g
WASTE TEMPORARY
VACUUM
VESSEL
1100 g
COOLING
SYSTEMS
PRIMARY FUEL SYSTEM
STACK
LOAD IN
EFFLUENTS
ITER SITE INVENTORY：2800 g
TORUS EXHAUST
130 g
POWER REACTOR：probably less
<100g
〜10g
LOAD OUT

17. POWER BLANKET (example)
Institute of Advanced Energy, Kyoto University
780K supercritical water
Li ceramic pebbles
He/H2 sweep for tritium
recovery
High Temperature
High Pressure
Fine tubings
Tritium Production
1st wall
Cooling tubes
Tritium Permeation could be ~100g day

18. Normal release from Fusion Facility
Institute of Advanced Energy, Kyoto University
　・ Normal tritium will be dominated by release from coolant
　・ Largest detritiation system will be for coolant
　・ Fusion safety depends on ACTIVE system.
Generalized fusion plant T R I U M E C O V Y P A L G N S D B K r e a c t o b u n d y s f i m l g - T R I U M H O G P ( k g / d a y ) A L N V E Y C S 1 3 6 . 5 t r i u m f l o w e a k / p n

19. Generalized detritiation system
Institute of Advanced Energy, Kyoto University
Generalized detritiation system
　・Detritiation for power train will depends on blanket types.
　・Normal detritiation for coolant will handle emergency spill.
　・Safety control with active system is not site specific. HX
Blanket
Turbine
tritium
tritium
Heat
Heat
Heat
Heat
Tritium recovery
Tritium recovery
Low concentration
Tritium recovery
Large throughput
Large enrichment
-broad concentration range
Closed cycle cascade
High concentration
Quick return
Once through

20. Detritiation systems of Plant
Institute of Advanced Energy, Kyoto University
Processes large throughput, lower concentration
Controls environmental release
Operational continuously (including maintenance)
Air Detritiation :
m3 / hour, possibly ci/m3 level
- leak from generator, secondary loops, hot cell
Water Detritiation : (isotope separation)
- 100 m3 / day, possibly 1000 ci/m3 level, 100g/day?
- driving turbine
Solid Waste Detritiation :
- 1 ton / day, possibly g / piece?
- materials (lithium, berylium, Steel) recycle
- needed both for resource and waste aspects.

21. Tritium confinement Institute of Advanced Energy, Kyoto University
Power train will be driven with tritium containing medium. T R I U M S C O N F E D W H L A Y B U I L D N G F E O P V A C M S T R Y H X
Cryostat
High temperature blanket will
require improved permeation control.
Pressurized gas may require additional expansion volume.
For gas driven system, large Expanson volume may be needed.
Expansion pool
Expansion pool

22. Emission from Fusion and Dose
Institute of Advanced Energy, Kyoto University
Emission from Fusion and Dose
Impact pathway of tritium suggests ingestion will be dominant.

23. Findings Institute of Advanced Energy, Kyoto University
Fusion plant detritiation will be dominated by power
plant configuration.
- Normal tritium release will be controlled actively.
- Off-normal spill can be recovered with normal detritiation.
- High temperature plant will require improved tritium system.
Measurable tritium will be released in airborne form.
Tritium accumulates in environment (far smaller natural BG).
Ingestion dose will be dominant.
For long run, C-14 may be a concern.

24. Conclusion Institute of Advanced Energy, Kyoto University
Fusion development is in the phase to study market
・Fusion must find customers and meet their requests.
・Fusion must satisfy environmental and social issues.
Development of advanced blanket is a key issue for fusion
・Economy - not just temperature, but to maximize market
・Environment - not just low activation, but best total cost
and social value / least risk(Externality)
Development strategy (road map) for blanket is needed.
・ITER and DEMO require 2 or more generations of blankets.
・staged improvement of blanket is planned with water-PB,
and LiPb dual coolant concepts.

25. Conclusion 2 Institute of Advanced Energy, Kyoto University
Possible blanket improvement
・Independent from large increment of plasma
・Continuous improvement
can be reflected in blanket
change.
(Improvement in DEMO phase)
・Multiple paths to meet
various needs are possible.
・Flexibility in development of
entire fusion program is
provided by blanket
development.
Fast Track