Response to the NAS Committee for a Strategic
Plan for U.S. Burning Plasma Research
Phil Ferguson
Director, US Virtual Laboratory for Technology (VLT)
Division Director, Fusion & Materials for Nuclear Systems, ORNL
Presented to:

National Academies Committee for a Strategic Plan for U.S. Burning Plasma ResearchAugust 29, 2017!

What is the US Virtual Laboratory forTechnology (VLT)?!
• Formed in 1998 to provide a single entity with central
leadership for the US fusion technology program!
– Provide advocacy for the technology program!
– Provide representation among the fusion program leaders!
– Build consensus within the program!
– Program management, guidance, and direction remains with FES!

• Largely dormant from 2013-2016 (Milora retirement)!
• New director named in May 2016!
• Currently 18 institutions!
– 8 universities, 1 private company, 9 national labs !
– ~8% of US non-ITER budget!

Topics to be addressed by the VLT!
• The importance of U.S. burning plasma research to
the development of fusion energy!
• The scientific and technical developments since the2004 report of the NAS Burning Plasma Assessment
Committee!
• Current status of U.S. research that supports burning
plasma science and advances fusion energy
technologies!
• Strategic elements that might strengthen or
accelerate U.S. burning plasma research!
All of these with a technology emphasis…!

“Experimental investigation of a burning plasma
remains a grand challenge for plasma physics and anecessary step in the development of fusion energy”!
National Research Council. 2004. Burning Plasma: Bringing a Star
to Earth. Washington, DC: The National Academies Press!

• As true now as it was in 2004!
– Strong consensus on this point, including among the technology
programs!
• “The creation of such plasmas is a necessary but not sufficientcondition for the development of a practical energy-producing
magnetic fusion power plant”!
– Also from the 2004 report, and also still true!
– Important questions for fusion nuclear science from burning plasmas thatmust be answered!

Near unanimous opinion that burning plasma science isamong the most important, or the most important, topic infusion energy research.!

The 2004 report anticipated participation in ITER driving
technology advancements in several areas!
• From the 2004 report, fusion technology advances from burning
plasma experiments were expected to include:!
– Breeding blanket development!
– Tritium processing!
– Magnet technology!
– High-heat-flux component development!
– Remote handling technology!

• ITER has driven progress in each of these areas, as well as:!
– Radiation transport!
– Disruption mitigation!

• Additional areas of progress (from the base program) includes:!
– Fusion materials!
– Plasma-materials interactions (PMI)!

A project approach like ITER drives a holistic approachto the fusion fuel cycle!
Characteristics of magnetic fusion!
Magnetic plasma
resists injection of
replacement fuel!
He “ash” andimpurity build-up
quenches fusion
reaction!
DT!
Plasma!

Tritium isradioactive andexpensive!
Only a fraction(~1%) of the fuelburns per pass!
Vacuum must
be maintained
around plasma!

Technology needs!

Fueling!

Tritium Processing!

Drives all Fuel Cycle
technology, including needfor tritium self-sufficiency!

Vacuum requires tritium
handling!

ITER Fueling Needs are Significant:!
!
! Cryogenic Pellet Injection is the Solution!
‒ ITER plasma volume is 840 m3 and scrape-off
layer is ~30 cm thick. This compares to 20
m3 and ~ 5 cm for DIII-D.!

PelletInjection‒ ITER is designed to operate at high density(> 1x 1020 m-3) in order to optimize Q.!
Gas!
Injection!

‒ NBI fueling to be negligible (< 2 x 1020 atoms/s or < 3 torr-L/s).!
‒ Inboard pellet injection planned for deep
fueling and high efficiency. Reliability must
be very high.!

ITER Cross
Section‒ ITER will require significant fueling capability
to operate at high density for long durations!
 Gas fuelling will be limited by poor
neutral penetration!
7	

ITER needs have driven advances in vacuum technology!
•
•
•

•
•

D++T+!
He++(3.5MeV)!
•n(14MeV)!

DT fuel is fused in the plasma and turned into Helium ash.!
Helium dilutes the plasma reducing the fusion efficiency if notremoved !
The divertor configuration allows the magnetically trapped plasma
particles to be neutralised and hence pumped by the vacuum
system !
To maintain a low helium concentration in the plasma continuous
high speed pumping (>50m3/s) is required in the divertor region. !
Vacuum pumping techniques developed for this application pump all
neutralized gases, so the fuel (>99%) and the waste helium (<1%). !
Pumping is performed:- !
––Divertor !

in first stage by specially developed cryo-sorption pumps with integral large
valves to allow cyclic regeneration. !
in second stage by cryo-condensation pumps (CVCs) with capability toseparate the fuel and helium and return the unused fuel to the fuel cycle. !

He, D2,T2,
impurities!

cryosorbtion
pumps !

Roughing
systemcontaining
CVCs!

ITER Vacuum Vessel Pressure Suppression Systemaddresses design basis accident scenarios!
••

Prevent the pressure in VV to exceed 1.5 bar(abs) for all design basis
accidents following an Ingress of Coolant Event!
Keep the VV below atmospheric pressure (dynamic confinement) for all
high probability in-VV accidental events: Loss of Coolant Accidents
combined or not with air ingress accidents!
Key features andVV!

Pressure relieflines!

4 vaporsuppression
tanks!

technological challenges:!
• Fast sub-atmosphericsteam condensation
with variable fraction of
non-condensable gases
over wide range of flow
rates!
• In-line management of
the hazard posed bypresence of flammable
Hydrogen-air mixturesin large varieties ofconcentrations!
9	Example: Scrubber column technology developed for
ITER-scale gas detritiation

Construction: Uses
industrial column
packing to promoteliquid-gas contact!

Concept: Clean water trickles
down on rising tritiated gas stream
and “scrubs” tritium out thoughisotopic exchange!

Performance: Detritiation
factor sufficient for safe
facility performance andcan be increased byraising liquid water flow
(λ=1 at equimolar liquidand vapor water flow)!

General Atomics Works with International Partners to
Manufacture the ITER Central Solenoid!
• Nb3Sn CICC Conductor
supplied by JAEA in
900 m lengths!

• 7 modules wound,
cured, insulated, andtested at GA!

Delivered to!
GA!

• 6 of these assembled
at ITER (1 spare)!

Delivered to!
Cadarache!

Completed module weighs 250,000
pounds has 560 turns (4 miles ofconductor) !
Design and manufacturing assisted via discussions
with Koreans, Japanese, Italians, Chinese

ITER Central Solenoid!

Collaboration between GA and ASIPP for ITER CS Final
Test System Feeder!
• CS Feeder system designed and built at ASIPP
based on ITER feeders!
• Testing of feeders performed at ASIPP with GA
assistance!
• Installation performed at GA as collaboration!
• Operational testing with balance of CS Final
Test System performed by joint GA/ASIPP
team!
Feeder under test at ASIPP

Test chamber and feeder installed at GA

Design of high heat flux components havematured significantly as a result of ITER!
•

Design reviews and schedule
drive engineered systems thatmeet fusion energy challenges!
– Cooling for high heat flux!
– Remote handling for replacement!
– No leading edges!

•

Result is a design that meetsspecifications and can beconstructed!
– ~2 m X 3 m structure!
– ~8 tons per cassette !
– Provides neutron shielding for
vacuum vessel!
– Joining of dissimilar metals has
been thought through!
– Alignment and adjustment has
been considered!

Remote Handling Technology Development for ITER
In-vessel component handling devices!

One of the main challenges specific to Remote Handling in ITER is the precise (millimetric)
handling of very large in-vessel components (weighing several tons) within radiation fields
of up to 500 Grays/hour. To develop and demonstrate the technologies necessary toundertake this task, in the context of ITER, full scale prototype devices have been built andtested in relation to both blanket and divertor remote handling. !
Blanket Remote Handling (Japan)!

Divertor Remote Handling (EU, Finland)!
toroidial mover!

Overview of the
ITER divertor
remotehandling
process.!

Overview of
the ITER
Blanket RH
System.!
radial mover!

Blanket module
handling trials using theprototype In-Vessel
Transporter (IVT) hosted
by the JapaneseDomestic Agency inNaka, Japan.!
(ITER Blanket module
weight is approx. 4tons).!

(ITER divertor cassetteweight is approx. 10tons).!

transfer cask!

Divertor cassettehandling trials in
the ITER Divertor
Test Platform
created by theEuropean Domestic
Agency in Tampere,
Finland.!

ITER-driven advances in radiation transport methods
development makes solutions possible!
•

New software provides major algorithmic and sharedmemory implementation improvements to the MCNP
code. Improvements were absolutely necessary tosimulate transport on ITER-released models with
useful speed and fidelity.!

•

Significant enhancements of hybrid MC-deterministic
methods (ADVANTG) specifically to visualize andgenerate MC variance reduction parameters for
ITER transport models.!

•

Shutdown dose rate analysis toolset (MSX/NAGSS)
created with bottleneck removal and parallelism in
mind. Toolset was built around the ORIGEN activation
solver for the largest ITER models and formallyvalidated for ITER fusion neutronics applications.!

•

CAD-to-MC model conversion and integration
process. Includes ITER-preferred model conversion
technology coupled with automated tools developed for
integration of different radiation transport models. !

Massive models (hundreds ofthousands of unique geometry
cells) of the ITER tokamak
integrated into full building
models with detailed
representations of importantequipment. !

World-leading hybrid methods allow radiation
challenges to be addressed!

Models developed to represent the entire
nuclear platform of the the ITER facility withhigh fidelity dose rate solutions to determine
whether personnel safety criteria are met
hundreds of meters away.!

Shattered pellet disruption mitigation systems havebecome reliable and robust through development andengineering support!

Barrel inner diameter increased to24.4 mm (from 16 mm diameter) inorder to study scaling of D2 andneon pellet formation/ acceleration.

Ice forming process in pipe gun
injector

Integrating any pellet system into a nuclear device is acomplex engineering challenge, and ITER has risen to thatchallenge!
Equatorial port plug:!
Implementation of 4 injectors!
Each with 4 barrels!

Shattered Pellet Injector DMS experiments on JET under
ITER/JET/US collaboration expands our existingknowledge on scalability towards fusion energy!
 Framework agreement has been signed
by IO-CT, USIPO, ORNL, US DoE,EUROfusion and CCFE!
 Testing SPI at JET is of high priority forthe following reasons:!
More energetic and larger target plasmas
and larger RE beam cross-section than in
DIII-D!
 JET could not demonstrate RE mitigation
with MGI into a full-blown beam!
 Impact of Be/W ITER-like wall on
disruption behaviour!
 Gain experience in operating SPI in amuch more stringent environment (RAMI)!

 Installation of a 3-barrel SPI, prototypicalfor that planned for ITER, on a top port at
JET!

SPI shatter tube fits inside verticalinjection line with bend justbefore entering the plasma.!

Fusion materials studies have made great advances
since 2004!
•

•

•

•

•

•

RAFM steels: high dose (>80 dpa) irradiation effects positively addressed; qualification for use inearly DEMO blanket in progress!
– Most of recent and planned high dose neutron irradiation studies are in US in international
collaborations. !
Advanced steels: CNA emerged as the new generation, computationally designed alloys; ODS
steels achieved progress in alloy design, understanding properties, fusion environment effects!
– US leadership in computational alloy design and development of advanced steels!
SiC/SiC: achieved rapid progress as an industrial material and nuclear structural material; on track
toward the first code-qualified low-activation structural material!
– US leadership in all aspects of SiC/SiC technology for nuclear; from materials development tocode qualification!
Tungsten: transitioning from poorly understood to material with basic properties and fusion
environment effects being understood!
– Future directions of tungsten-based PFM development becoming clear!
– Case for tungsten sets a model of multi-angle evaluation of candidate/emerging PFMs!
Emerging materials: high entropy alloys, bulk metallic glasses, MAX phases, ultra-high temperatureceramics, high entropy ceramics, etc. – initial studies presented promises!
– Bridge design window gaps for conventional materials!
– Enable novel component designs and reactor concepts!
Advanced manufacturing: rapid progress over last decade (outside fusion program)!
– Opens routes to develop novel materials that were inaccessible with conventional
manufacturing techniques; beyond rapid prototyping and complex net-shaping!

JP-28!

JP29!

Start	

April, 2005	

Jan., 2005	

Finish	July, 2013	

July, 2013	

Temperature (oC)	

300/400/500	
 300/400/500	

Max dose (dpa)	

87	

87	

# of reactor cycles	

46	

46	

Ultimate tensile strength(MPa)	High dose irradiation effects addressed for reducedactivation ferritic/martensitic steels!
1200	

T. Hirose et al., ICFRM-17!

1000	
800	
600	
400	
200	
0	
200	

Unirr.	
mod3̲HFIR	
Ni60̲HFIR	

300	

IEA̲HFIR	
Ni58̲HFIR	

400	

500	

600	

Temperature (oC)	

•••300 oC irradiated (JP29 #13)
	Fission neutron irradiation effects were addressed in
US/Japan HFIR JP-28/29 experiment to maximum
dose of 87 dpa (more than 8 years of irradiation)!
Hardening and ductility degradation appeared
significant and unsaturated at 300°C!
Helium effects on mechanical properties appeared
insignificant as studied by Ni isotope tailoring!

Silicon carbide composite developed from low TRL into
industrialized nuclear structural material!
••••

Nuclear grade SiC/SiC developed in fusion program inearly 2000ʼs!
Proved to be highly radiation-stable in broad temperature/
dose ranges!
Radiation-tolerant joining technologies were successfully
developed in fusion program!
Rapid technology development driven by interest fromaircraft engine and fission energy R&D communities!
T. Koyanagi et al., J.Nucl.Mater., 2016 !

Y. Katoh et al., J.Nucl.Mater., 2014 !

Radiation-tolerant joining for SiC/SiC!
Exceptional irradiation creep resistance for SiC!

Progress has been made on understanding radiation
hardening of ferritic/martensitic steels!
Current steels

Next-generation(TMT, ODS) steels
Dramatic reduction in radiation
hardening occurs when average
spacing between defect cluster
nuclei (dislocation loops, etc.) ismuch greater than average
spacing between defect sinks!

Nloop-1/3 >> Stot-1/2 !
or equivalently,!
Stot >> Srad defects !
S.J. Zinkle and L.L. Snead, Ann
Rev. Mat. Res., 44 (2014) 241!
S.J. Zinkle et al., Nucl. Fusion 57(2017) 092005!

Thermomechanical treatment improves creep rupture
behavior over conventional 9Cr steels!

50-100% improvement increep rupture strength for
newly designed reduced
activation steels!

Predicted improvement inradiation resistance as well!

S.J. Zinkle et al., Nucl. Fusion 57 (2017) 092005!

Behavior of tungsten in an irradiation and plasma
environment is being understood !
L.M. Garrison et al., J.Nucl.Mater. 2016!

Hardening and severe
embrittlement in
irradiated tungsten!
C.M. Parish et al., Scr.Mater., 2017 !

•
•
•
•

Complex radiation effects in tungsten are finallygetting clarified in a systematic manner!
Provides information on thermo-mechanicalperformance envelopes for PFCs!
Important implications to design space fortungsten-based composite materials!
“Case for tungsten” useful in exploring andassessing emerging materials!

Re (red) and Os (yellow) in irradiated W
revealing detailed precipitation features!

Linear devices have developed to the point of providing
ITER relevant fluxes/fluences for PMI studies!
PISCES!

104 seconds of ITER Divertor Flux!

643 K!
8 mm thicksamples
1 mm thicksamplesR. P. Doerner et al. NME 2016
http//dx.doi.org/10.1016/j.nme.2016.04.008.

••

No saturation in D retention
in W with high-fluence
deuterium plasma exposure
5% He+ flux during
deuterium plasma exposure
drastically reduces D
retention in W at 643 K

Fusion Nuclear Science has been identified for morethan a decade as an important program element!
•

2005 FESAC “Scientific Challenges, Opportunities and Priorities for the US
Fusion Energy Sciences Program”!
– Identifies key thrusts including fusion materials, systems engineering, fueling, etc.!

•2007 FESAC “Priorities, Gaps and Opportunities: Towards a Long-Range
Strategic Plan for Magnetic Fusion Energy”!
– Identifies predictive modeling, transients, magnet technology, etc.!

•2009 Research needs for Magnetic Fusion Energy Sciences!
– Major thrust of “Harnessing Fusion Power” includes fuel cycle, power extraction,materials science, etc.!

•

2014 FESAC Strategic Planning and Program Priorities Report!
– Identified fusion nuclear science among four high priority areas!

•

2015 FES Community workshops focused on three areas with wide community
support!
– Transients, whole device modeling, & plasma-materials interface!

So where are we now?!
• Fusion nuclear science and technology exists as a stable part of the
US program!
– ~8% of the FES budget has gone into the FNS&T program for the last 3
years!
• An energy program will require additional investment!

– Program is highly leveraged where possible (NE, BES, University
investment, Lab investment, etc.)!
– There are fusion specific challenges that are not funded external to theprogram (fusion specific, e.g., tritium retention in PFCs, etc.)!

• Fusion nuclear science covers many topics!
– The US canʼt and shouldnʼt do everything; there is not enough time orbudget!
– International collaboration will play a vital role in FNS&T!

• Three areas of prime opportunity are fusion materials, fusion fuel cycle,
and power handling!
– Other opportunities, like liquid metals and HTS, will be discussed briefly!

Fusion materials leadership is strong!
• The US is a leader among the international fusion materials
program!
– US-Japan collaboration is more than three decades strong, andcontinues to make key contributions (current PHENIX collaboration)!
– US is executing a structural materials irradiation and PIE for theEUROfusion program (Europe is outsourcing work and recognizing US
expertise)!
– Consistent request for review participation by US program members!

• However, resources are limited!
– With existing budget, prime focus is structural materials and existingmaterials!
– Not much effort on blanket materials or materials development!
– Even PMI science is not a large program in the US!

• Opportunities for leadership include:!
– PMI, fusion relevant neutron source, and modeling & simulation!

Three PMI facilities would position the US uniquely toaddress challenges!
• TPE addresses tritium
retention in damaged
samples!
• PISCES is a high fluence
facility with beryllium
capabilities to address
ITER challenges!
• MPEX will be a DEMOlevel fluence device withtilted target & neutron
irradiated capabilities!

A fusion relevant neutron source is an internationalneed, and a US opportunity!
•
•

•
•

•

High displacement rate irradiations have been
carried out in HFIR for decades!
A neutron source with the correct energy spectrum,
producing gas synergistically with displacements, isneeded for material qualification!
IFMIF has been discussed for decades!
DONES is the latest version, with reduced scope(30-40 dpa vs 150 dpa) but still costing hundreds ofmillions of dollars!
It is time to consider nearer term, lower cost options
with reduced performance compared to DONES!
– Phoenix Nuclear Labs has a proposal for a DT neutron
generator!
– A Gas Dynamic Trap proposal has been mentioned!
– Spallation sources can provide low displacement data!
• Transmutations become an issue as total
displacements rise!

Phoenix Nuclear Labs
neutron generator concept!

Modeling is a critical part of addressing the materials
challenge!
• Experiments help us
understand the physics, so
we can accurately model awide range of scenarios!
• The PSI SciDAC is making
progress on modelingmaterials challenges fromfirst principles tomacroscopic effects, overlarge length and timescales!
• Leverages ASCR/HPC and
NE investments!

BD Wirth, K.D. Hammond, S.I. Krashenninikov, and D.
Maroudas, Journal of Nuclear Materials 463 (2015) 30-38.!

Closing the fuel cycle is a critical part of fusion energy!
• Analysis shows there is likely enoughtritium for ITER and possibly one
DEMO (startup=5-15 kg)!
– Control of production and consumption
is largely outside of fusion community
control!
• Korvai, et al, Nuclear Fusion (in press);
Federici, SOFE 2017 presentation!

– Without a closed fuel cycle, we needtritium production from fission power
plants!
• Why have additional complexity offusion power plants if fission plants are
required?!

• We must close the fuel cycle for any
fusion energy system!
• Must actually do better than that tostart additional plants in the future!

CFETR!
Scenario	
  A:	
  
-­‐	
  Romania	
  does	  not	
  extract	
  their	
  T	
  
-­‐	
  All	
  HWRs	
  ﬁnish	
  their	
  lives	
  ~30y	  and	
  some	  HWRs	  are	
  refurbished	
  +25y	  Scenario	
  B:	
  
-­‐	
  Romania	
  extracts	
  their	
  T	
  
-­‐	
  Several	
  refurbishments	  Scenario	
  C:	
  
-­‐	
  All	
  known	
  refurbishments	
  go	
  ahead	  and	  then	
  some	  more!	  -­‐	
  Romania	
  builds	
  two	  new	
  CANDUs	
  in	
  the	
  mid-­‐2020s	
  (and	
  refurbishes	
  them)!

Tritium inventory & release are significant issues forfusion energy!
••

Fission power reactors (typical annual tritium discharges of 100-800 Ci/
GWe; ~10% of production) are drawing increasing scrutiny for tritium release!
1 GWe fusion plant will produce ~109 Ci/yr; historic assumed allowed
releases are ~0.3 to 1x105Ci/yr (<0.01% of production)!
– Public concern about tritium release from fission plants suggests actual release
may be limited to ~100 Ci/yr (10-7 of production)!
– Can fusion achieve 106 times better tritium control than operating fission plants?!

• Tritium inventory and release pathways in fusion plants are poorly
understood !
– Nanoscale cavity formation may lead to significant trapping of hydrogen isotopes
in the blanket structure (tritium inventory issue)!
– Tritium trapping efficacy of precipitates, nanoscale solute clusters and radiation
defect clusters (blanket & piping) is poorly understood from a fundamental
perspective!

Leadership opportunities in fuel cycle research exist!
• US has leadership in tritium science and handling due to theactivities at defense/nuclear labs (LANL, SRNL, & INL)!
• Efficient tritium handling, including extraction in flowing liquids andsafety, is a challenge where the US can lead!
• Tritium breeding blankets are among the lowest TRLs in fusionenergy!
– US (UCLA) strength in liquid metal modeling and experiments !
– Several international collaborations in blankets!

• US leadership in pellet fueling!
– Current discussions/plans for installations on W7-X and MAST-U!

Demonstration of Direct LiT Electrolysis using an
Immersion Cell!
Scientific Achievement!
• Direct LiT electrolysis has the opportunity to simplify tritium
recovery from a liquid lithium cooling blanket• Improvement of the conductivity and structural integrity ofthe solid lithium ion conducting materials is critical tocreating a viable direct LiT electrolysis process.

Significance and Impact!
A direct LiT electrolysis process can eliminate the need touse molten salts for LiT recovery and can eliminate theneed for centrifugal separators used in the Maroni
process for LiT recovery

Research Details!
• A sol-gel method was developed for LLZO synthesis thatenabled a reduction in grain size to between 0.5 and 0.8
microns as opposed to 2-3 microns for the solid state
reaction pathway• The ionic conductivity of the electrolyte is a function of anumber of variables, including grain size. The reduction in
the LLZO grain size should enable increased conductivity.

Grain size reduction for Lithium
Lanthanum Zirconate (LLZO) achievedby using a sol-gel method of synthesis
as compared to a solid-state reaction
methodDealing with power exhaust from a fusion energy
device is a recognized challenge!
••

The US is not currently world leading in thisarea from a fusion nuclear science point ofview!
We should leverage our strengths to address
this challenge!
– New materials may provide a solution to
the power exhaust challenge, and the US
is a world leader in materials!
– Additive manufacturing may change thegame, and the US is among the world
leaders in additive manufacturing!

Addressing Power Handling Challenges Can Involve
New Materials!
Achievement• Demonstrated that a nearly isotropic highconductivity, low-Z plasma facing material is possible
by combining pyrolytic graphitic ligaments with anisotropic-engineered microstructure!

Significance and Impact• For the first time, the thermal efficiency of low-Z armor
is comparable to the copper heatsink!
• Max Planck IPP interested in fielding the monoblockin the W7-X stellarator for potential use in divertor
scraper element!

Research Details• Densified graphitic foam and mock-ups produced!
• Thermal properties measured, k=265 W/mK to date,expect 350 W/mK!
• Robust braze joint obtained on CuCrZr tubes!
• Hot water IR thermography showed that using nobraze joint actually delivers best thermal performance!
• Thermal modeling and tomography of microstructure
is in progress!

Allcomp densified foam!
>350 W/mK, ~1.5 g/cc!

Advanced manufacturing has been demonstrated on
nuclear components!
• HFIR annular control plates used 1960s
technology based on the original design!
– Costly, low yield to meet specifications!

• A joint project between the nuclear fuelmaterials group, HFIR staff, and the
Manufacturing Demonstration Facility at ORNL
was initiated in 2014!
• Multiple techniques were tested!
– The cost was less than we initially thought, andwas more successful than we could haveimagined!

Advanced manufacturing coupled with HPC can leadto innovative solutions for power handling!
• Additive manufactured parts for HHF
testing can be produced and tested!
• Positron emission particle tracking(PEPT) is used to experimentally
validate computational tools!
– Remove large conservatism fromaverage heat transfer coefficients!

• After validating computational tools,
HPC can be used to scan a vastarray of geometries for additive
manufacture!
– Optimize the heat transfer capabilities
without human bias!

• Test the new components!

Liquid metals are a potential PFC solution for power reactors!
• Liquid metals (LMs) provide a selfhealing and renewable plasmaLi CPS (first wall,
facing material!

Energy Transport Mode!

divertor)!

• LMs eliminate long-time constants
associated with plasma-induced
wall evolution!
• LMs separate neutron damage
effects from plasma-materialinteractions!
• LMs add additional methods for
power-exhaust!
– Lithium vapor divertor and fastflow concepts can both greatly
exceed current technologicallimits!

Li Vapor Box,
ARLLD (divertor)!

Evaporative andRadiative Cooling!

FLiLi (first wall)!
Heat Conduction
Sn CPS!
(first wall,divertor)! to Substrate!
LiMiTs!
(first wall, divertor)!

Heat Convection
by Liquid Metal!

Fast Flow, ACLMD!
(first wall, divertor)!
See also: M.A. Jaworski, et al., “Breaking through toReactor Solutions with a Focused, Liquid Metal Program”
white paper submitted to the USMFRSD workshop!

High temperature superconductors may provide an
opportunity for fusion energy development!
•••

High-field, high-temperature superconductors (HTS) may enable a newgeneration of compact fusion experiments and power plants, dramatically
speeding up the development path and improving the overall attractivenessof fusion energy!
The advantages of HTS are that they can operate at very high magnetic
field, high cryogenic temperature, high current densities, and larger
mechanical stresses and strains!
HTS can significantly enhance the performance and feasibility of almost any
type of magnetic confinement device, including:!
–
–
–
–
–
–
–

Tokamaks!
3D shaped devices such as stellarators and other helical configurations!
STs!
FRCs!
gas dynamic traps!
magnetic mirrors!
levitating dipoles!

Summary!
•

Burning plasma research is recognized as a key element in thedevelopment of fusion energy!
– There are technology implications beyond the physics questions that must be
answered!

•

Tremendous advances have been made in fusion nuclear science &technology since the 2004 report!
– Advances beyond those predicted in 2004 have been achieved!
– Many of these advances have been driven by ITER and the need for design solutions!

•••

Fusion nuclear science is an identified need, and an opportunity for world
leadership for the US program!
A growing fusion nuclear science program is needed to prepare the US for
the next step toward fusion energy!
Fusion materials is already an area of leadership, but offers opportunities!
– PMI, blanket materials, fusion relevant neutron source!

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Fuel cycle is also a strength and offers opportunities!
– Tritium handling, safety, breeding, and fueling!

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Power handling is a challenge where we are not world leading, but can beby applying our strengths!
– New materials, advanced manufacturing, and HPC!