Japanese Perspectives on Liquid Blanket Research and Relating Collaboration

1
Japanese Perspectives on Liquid Blanket Research
and Relating Collaboration

• T. Muroga
• Fusion Engineering Research Center,
• National Institute for Fusion Science, Japan

APEX/TBM Project Meeting November 3-5, 2003, UCLA
2
Japanese Fusion Research Organizations
Two organizations carry out fusion research in
Japan JAERI Mission given by the
government Project-oriented ITER official
contractor (at present) Universities (group of
independent Professors) Mission defined by their
own (more interest-oriented) Project by mutual
agreement Scientific approach Playing
complementary roles but sometimes causing
problems (especially in making national decisions)
3
Introduction of NIFS-FERS
NIFS (National Institute for Fusion Science) is
the inter-university research institute Coordinati
on and enhancement of University research LHD as
the core project Fusion Engineering Research
Center in NIFS Established in 1999 Coordination
and enhancement of University activity
on Structural Materials Blanket (started 2001,
activity still limited) SC system (nuclear
technology related, 2003)
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Introduction of NIFS-FERS (cont.)
Present activities of NIFS-FERS Development of
vanadium alloys (JAERI is the core for
RAFS) Fabrication of reference ingots and
characterization by universities MHD coating
(started in 2000) Fabrication and corrosion
tests Netronics (started in 2002) Liquid
blanket, IFMIF IFMIF-Key Element Technology
Verification Collaboration with universities (Li
free surface in Osaka -) ITER-TBM needs
coordination of Universities and thus potential
major activity of FERC in the future
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Outline of Presentation
What is agreed in Japan as strategy for liquid
blanket research? Roadmap to powerplant Responsib
ility sharing between JAERI and
Universities/NIFS Research emphasis in
Universities/NIFS ITER participation/contribution
(Including TBM) International collaboration
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General Classification into Two Lines for Fusion
Development
Fast realization of power demonstration Considered
to be important for public support Based on
modest progress in science/technology Relatively
large budget allocation for near-term Project-orie
nted approach Currently JAERI is the core for
this line Exploration of advanced system
Long-term research including fundamentals Increas
ing attractiveness (cost, safety, environment) is
thought to be crucial for fusion
development Science-oriented approach Currently
University/NIFS is the core for this approach
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EU Strategy Has Also Two Lines
Reference system
Advanced system
Lackner, ICFRM-10
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Two Lines for Materials/Blanket in Japan
Fast realization line RAFM/water as a reference
system RAFM/Supercritical water (optional
1) ODS/Supercritical water (optional
2) Relatively large budget allocation for the
development RAFM test planed to be dominant in
early stage of IFMIF Advanced line Presently
liquid blanket systems (V/Li and Flibe) and
SiC/He Focusing on fundamentals and key
feasibility issues Science-oriented approach
University/NIFS is the core for this
approach Major subjects of JUPITER-II
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Two Lines for ITER-TBM(preliminary discussion)
Fast realization line RAFM/water TBM Efforts
focused on Day One TBM Contribute to licensing
First Power Generation Plant together with early
IFMIF data Advanced line Liquid blanket systems
(V/Li and Flibe) and SiC/He Plan to start TBM
either from Day One or in the later phase of
ITER Agreed to keep these activities irrespective
of the selection on Day One TBM
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Schematic Roadmap for Materials and Blanket
Development in Japan
Fast realization line (Currently JAERI leadership)
Advanced line (Currently NIFS/University
leadership)

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Recent Activity of ITER-TBM in Universities/NIFS

• From Japan, only solid breeders were proposed to
  ITER via JAERI
• Participation to scientific aspects of ITER
  research by NIFS/ Universities is being enhanced
• A NIFS-collaboration activity started in 2002, in
  which liquid blanket test module is explored

Party Proposed TBM-type
JAPAN Solid - Water
JAPAN Solid - Helium
EU Solid - Helium
EU Li-Pb - Water
Russia Solid - Helium
Russia Lithium
US Solid - He
US Lithium
Party Proposed TBM-type
JAPAN Solid - Water
JAPAN Solid - Helium
EU Solid - Helium
EU Li-Pb - Water
Russia Solid - Helium
Russia Lithium
1995
2001

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NIFS Collaboration Activity for ITER-TBM

• Examination of Li/V first and then followed by
  Flibe
• Support from JAERI
• First output expected in 2004

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Purpose of Li/V ITER-TBM(current discussion)

• Feasibility of no-Be and natural Li blanket
• Use of 7Li reaction for enhancing TBR in contrast
  to Russian Be6Li enriched TBM
• Validation of neutronics prediction
• Technology integration for V-alloy, Li and T

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ITER with Li/V self-cooled blanket - MCNP
calculation by T. Tanaka (NIFS) -
Inboard
40 cm
SS, H2O
A
Blanket
FW
Vacuum vessel
Plasma
B
V-4Cr-4Ti walls, Natural Li
SS (60), Li coolant (40)
Outboard
Coil structure
40 cm
1 m
Vacuum vessel Filler
SS, H2O
SS, H2O
Center solenoid
A
Blanket
Vacuum vessel
FW
Blanket
A Standard ITEF-FEAT blanket
B
B ITER with V/Li full blanket
Input geometry for MCNP calculation
SS (60), Li coolan (40)
V-4Cr-4Ti walls, Natural Li
(Dimensions from ITER Nuclear Analysis Report)
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ITER with Li/V self-cooled blanket - Local TBR -
Local TBR (Full Coverage)
Inboard Outboard Total Contribution of 7Li ()
Li/V blanket 0.30 0.92 1.22 33
Coolant in filler 0.029 0.15 0.18 2.6
Total 0.33 1.1 1.4 ---
( JENDL 3.2)
(a) Inboard
(b) Outboard
FW
FW
Blanket
Blanket
Filler
Filler
Distribution of tritium production rate
Significant contribution of 7Li to TBR
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Neutron spectrum at first wall of Standard and
V/Li Blanket
Comparison of Neutron Flux at Outboard First Wall
Cross Section for Tritium Production (JENDL 3.2)
Significant difference between thermal neutron
component in ITER-FEAT and ITER-Li/V Thermal
neutron should be shielded in the TBM area of
ITER-FEAT for the purpose of simulating V/Li
blanket condition
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Russian Li/V self-cooled test blanket module -
Structure -
505
WC Shield (Reflector)
Be multiplier
SS(60) H2O(40)
Plasma
1720
V-5Cr-5Ti
Li layer (6Li 90)
Structure of Russian Li/V TBM
(Unit mm)
6Li enriched coolant (7.5 gt 90)
Li layer x 2, Be multiplier gt 6Li (n, a) T
Maximize the 6Li reaction to demonstrate DEMO
reactor breeding tritium by 6Li
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Russian Li/V self-cooled test blanket module -
Tritium production -
Total 0.09 (g/FPD)
SUS H2O
Plasma
Li layer (1)
Li layer (2)
TBM surface
Tritium production rate in Li layers and
contribution of 6Li and 7Li
SS316 TBM frame
Li/V TBM
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Tentative design of Li/V self-cooled TBM by
NIFS/Universities
505
Verification of (1) Coolant circulation (2)
MHD coating
SS(60), H2O(40)
Plasma
Li layer
V-4Cr-4Ti
Verification of (1) Neutron transport (2) Tritium
production from 7Li
SS316 TBM frame
210
1720
210
470
Plasma
Inlet/outlet pipes
SS(60), H2O(40)
Li 0.027 m3
Li/V TBM
(Unit mm)
Tentative design of Li/V TBM
Verification of TPR for 7Li
Thick Li tanks for verification of neutron
transport
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Tentative design of Li/V self-cooled TBM -
Tritium production -
Covering by B4C
For verification of tritium production
from 7Li (n, na)T reaction
Plasma
SS(60), H2O(40)
- Reduction of thermal neutrons
by B4C shielding
(3)
Li layer (1)
(2)
(4)
(5)
Li layer (1)
Li layer (1)
(2)
(2)
(3)
(4)
(5)
(3)
(4)
(5)
Contribution of 7Li to tritium production
Tritium production rate in Li layers
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Experimental parameter for Li/V TBM - Adjustment
by B4C shield -
10 cm in front side
Li/V TBM
10 cm in rear side
10 cm in front side
Li/V blanket
10 cm in rear side
Russian TBM
Changes in contribution of 7Li by B4C covering
Contribution of 7Li to TPR can be adjusted by
thickness of B4C shield
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Future Participation to ITER-TBWG(discussion not
started)
Discussion on participation of University/NIFS to
ITER-TBWG will start soon Possible options may
be Tune the present blanket activity to TBWG
schedule Start engineering design for V/Li
TBM Concept definition and start engineering
design for Flibe TBM Keep the present pace with
weaker interaction with TBWG In this case, we
will not strongly propose Day One TBM Keep the
present advance blanket research activities
irrespective of the selection on Day One TBM
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JUPITER-II
JUPITER-II is a mission-defined collaboration
program Advanced blanket (in contrast to JAERIs
FS/water) Task plan and Check and Review Use
of core facilities (HFIR, STAR --), which
are unavailable in Japan, is the rationale for
the collaboration (transferring budget from J to
the US) Major change of the framework need
re-evaluation by standing committees and will
face a risk Most Japanese JUPITER-II participants
have strong scientific interests in the present
tasks and have small incentive to make extensive
change in the framework
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JUPITER-II Possible Fine Tuning(unofficial,
Muroga private idea)
We cannot propose any concept for ITER-TBM at
present with the lack of corrosion data
(Sze-Muroga e-mail agreement) Shift some effort
from vanadium irradiation to MHD
coating/corrosion MHD coating is the critical
issue for both long term blanket development and
entry to Day One TBM REDOX,Flibe-materials
interaction should be enhanced MHD related design
activity should be enhanced Lenient requirement
to MHD coating for V/Li However, HFIR and
Tritium activity must be maintained because of
program need and participants incentives
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Comment/questions to US Discussion on TBM
Selection
What is the philosophy of selecting TBM?
Technical feasibility and ? Japan Roadmap to
Powerplant What is the community selecting
TBM? Liquid breeder for Japan
University/NIFS including B, M, T, S (If
materials people are not involved heavily, the
impact of the decision on materials program must
be small) Why two options (only because of
budget?) Number of available port no longer the
factor What is the fate of the concepts not
selected for the first-day TBM? (Longer-term
strategy)
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End of presentation
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MHD Coating Necessity
Magnetic Field
Duct
MHD Pressure Drop
Load to pumping system Force to structures
Li Flow
Force
Pressure Drop proportional to Flow
length?Velocity?B2?Duct thickness?Conductivity of
Li and Duct
Insulator coating inside the ducts a possible
solution
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MHD Coating Candidates (1)Free Energy
Stable ceramics in a quite reducing condition
Selection from the free energy data
CaO?Y2O3?Er2O3? CaZr(Sc)O3? AlN?BN
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MHD Coating Candidates (2) Bulk Compatibility

• Potential candidates
• Y2O3
• Er2O3
• AlN with N control
• CaZr(Sc)O3 (700C)
• others

Japan-US JUPITER-II Collaboration (Pint, Suzuki
et al. 2002)
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MHD Coating DevelopmentPresent Efforts

• Development of coating technology
• RF-sputtering
• EB-PVD
• Arc Plasma Deposition
• Characterization of the coating
• Resistivity
• High temperature stability
• Compatibility with Li
• Radiation induced conductivity
• In-situ coating technology

Japan-US JUPITER-II Collaboration (Suzuki, Pint
et al. 2003)
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In-situ Coating

• The in-situ coating method has advantages as,
• possibility of coating on the complex surface
  after fabrication of component
• potentiality to heal the cracks without
  disassembling the component
• CaO coating has been explored

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Problems of the CaO Coating and New Effort on
Er2O3

• It was found that the CaO coating, after
  formation, dissolved at high temperature (600,
  700C)
• CaO bulk is inherently not stable in pure Li at
  high temperature, continuous supply of oxygen is
  necessary to maintain the coating
• Er2O3 is much more stable at high temperature
• It is expected Er2O3, once formed, be stable in
  Li for a long time
• Er2O3 is stable in air, combination of
  dry-coating and in-situ coating is more feasible

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In-situ Er2O3 Coating on V-4Cr-4Ti

• Er2O3 layer was formed on V-4Cr-4Ti by oxidation,
  anneal and exposure to Li (Er) at 600C
• The coating was stable to 300 hrs
• The resistivity was 1013 ohm-cm

Oxidation and anneal at 700C for 16 hr
Oxidation only
Oxidation at 700C
100 nm
6 hr
1 hr
Yao. 2003
XPS depth profile after exposure to Li (Er) at
600C for 100 hr
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Need for Collaboration with Design People

• Requirement to the coating performance depends
  strongly on the design
• System design is necessary to quantify the
  requirement to the coating
• Clever design would make the requirement lenient
• New idea of coating will be obtained by
  collaboration with design
• Laminar coating structure, etc.

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Meeting Summary for Crack Fraction Allowance for
the MHD Coating (Sze Aug.03)

• For a single pipe, with a perfect insulating
  coating, the allowable crack fraction was lt10(-7)
     
• For a real coating, 10(-2) is achievable, while
  10(-4) might be achievable. 
• If we start with a poor coating, the allowable
  fraction can be higher, maybe 10(-4), with a
  higher MHD pressure drop.
• There are other ways to increase the allowable
  crack fraction, such as change the aspect ratio
  of the channel, change the boundary conditions of
  the flow channel.
• The boundary condition of the flow channel, such
  as the contact resistance between the fluid and
  the wall, may have major impact on the crack
  fraction.   
• The change of the designs may have major impact
  on the crack allowance.

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Impact of Sze Summary on the Coating Development
in Japan

• Experimental examination of the resistance
  between the (flowing) Li and the wall covered
  with cracked coatings at high temperature is of
  high priority. 
• The goal of the in-situ healing may be set to
  increase the resistivity of cracked area from
  complete conduction by 4 order of magnitude
• Increased collaboration between materials and
  design people in Japan

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Design Effort to Reduce Requirement to the
Coating

• Optimization of channel structure for reducing
  the requirement to the coating
• Coating may be necessary only on limited flat
  surfaces
• Insulator ribs may be inserted instead of coated
  ribs/walls
• Other suggestions on laminar coating structure,
  enhanced heat transfer, etc

(Hashizume)
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Summary

• Collaboration by Materials, Blanket and Design
  people are increasing on V/Li system in Japan
• Progress in developing vanadium alloys toward
  engineering maturity
• Enhanced Li technology by IFMIF-KEP
• Increased accessibility for the liquid blanket
  people to ITER-TBR
• Collaboration on MHD-coating development by
  materials and design people
• One of the goals of the collaboration is to
  propose V/Li ITER-TBM
• The collaboration is enhancing research for other
  advanced blanket systems (Flibe --)
• The collaboration covering Material, Blanket and
  Design people in the US will accelerate the
  progress, and should be enhanced in the framework
  of JUPITER-II