Summary of Preliminary
Conclusions of the ReNeW
Fusion/Fission Hybrid
Blanket Panel
Presented by:
Neil B. Morley, Adj. Professor
UCLA Fusion Science and Technology
Research Needs Workshops
Fusion/Fission Hybrid
Gaithersburg, MD, Sep 30 – Oct 2, 2009
077-05/rs
The Hybrid Blanket Panel
 David Petti – INL, Lab Fellow, Director R&D for NGNP, Former Fusion
Safety Program Leader
 Jess Gehin – ORNL, Senior Program Manager Nuclear Technology
Systems, Former Leader of Reactor Analysis Group
 Jake Blanchard – UW, Professor of Engineering Physics,
Thermostructural/EM/Lifetime aspects of fusion structures
 Per Peterson – UCB, Professor of Nuclear Engineering, High
temperature fission and fusion energy systems, nuclear security
and waste management
 Mohamed Abdou – UCLA, Distinguished Professor of Mechanical
Engineering, Director of the Center for Energy Science and
Technology Advanced Research (CESTAR) and the Fusion Science
and Technology Center
 Neil Morley – UCLA, Adj. Professor of Mechanical Engineering,
Fusion Blanket Design and Cooling Technology
Contributions from Bill Stacey, Mike Kotschenreuther, Ralph Moir and
Wayne Meier are also acknowledged
077-05/rs
Outline
 Introduce the Panel
 Fusion and Fission blanket requirements
 Sample of Fusion/Fission Hybrid blanket concepts
 Potential advantages of Hybrid blankets
 Concerns about Hybrid blankets
 Omission, Conclusions and the Parallel Session
077-05/rs
Pillars of a Fusion Energy System
1. Confined and Controlled
Burning Plasma (feasibility)
2. Tritium Fuel Self-Sufficiency
(feasibility)
3. Efficient Heat Extraction and
Conversion (attractiveness)
4. Safe and Environmentally
Advantageous
(feasibility/attractiveness)
Fusion Nuclear Science and
Technology plays the KEY role
5. Reliable System Operation
(attractiveness)
Yet, keep in mind that no fusion energy relevant first wall
and blanket component has ever been built or tested
077-05/rs
4
Scope of Blanket and Nuclear Technology
The scientific issues, technical
disciplines, materials, engineering and
development of fusion nuclear
technology components:
From the edge of Plasma to TF Coils:
1. Blanket Components (including FW)
2. Plasma Interactive and High Heat Flux
Components (divertor, limiter, rf/PFC elements)
3. Vacuum Vessel & Shield Components
Other Systems / Components
affected by the Nuclear Environment:
4. Tritium Processing Systems
5. Remote Maintenance Components
6. Heat Transport, Power Conversion
Systems
ARIES-AT FNST COMPONENTS
077-05/rs
5
Blanket functions including first wall
A. Power Extraction
–
Absorb plasma radiation on the first wall and convert
kinetic energy of neutrons and secondary gamma
rays / charged particles into heat
–
Extract the heat (at high temperature, for energy
conversion)
B.
Tritium Breeding and Extraction
–
Must have lithium in some form (ceramic, liquid
metal, etc)
C.
Physical Boundary for the Plasma
–
Physical boundary in contact with the plasma, wall
conditioning, Provide access for plasma heating,
fueling
D.
Radiation Shielding of the Vacuum
Vessel and Magnets (Usually)
E.
–
Plasma
n
n
Blanket
n
p
p
p
n
HYBRID -- Transmutation, Energy and
n
Neutron multiplication, and/or Fissile
Fuel Production
ALL FUSION NEUTRONS NEEDED FOR
Minimize parasitic absorption. Moderation /
transmission of fusion neutrons to fission fuel
BREEDING TRITIUM, STRONG
6
MULTIPLICATION NEEDED FOR
HYBRID
077-05/rs
Summary of Top- Level Technical Issues for
Fusion Nuclear Science and Technology
1.
2.
D-T fuel cycle tritium self-sufficiency in a practical system
Tritium extraction, inventory, and control in solid/liquid breeders and blanket, PFC, fuel
processing and heat extraction systems
3. MHD Thermofluid phenomena and impact on transport processes in electricallyconducting liquid coolants/breeders
4. Structural materials performance and mechanical integrity under the effect of radiation
and thermo-mechanical loadings in blanket and PFC
5. Functional materials property changes and performance under irradiation and high
temperature and stress gradients (including ceramic breeders, beryllium multipliers,
flow channel inserts, electric and thermal insulators, tritium permeation and corrosion
barriers, etc.)
6. Fabrication and joining of structural and functional materials
7. Fluid-materials interactions including interfacial phenomena, chemistry, compatibility,
surface erosion and corrosion
8. Interactions between plasma operation and blanket and PFC materials systems,
including PMI, electromagnetic coupling, and off-normal events
9. Identification and characterization of synergistic phenomena and failure modes, effects,
and rates in blankets and PFC’s in the fusion environment
10. System configuration and Remote maintenance with acceptable machine down time
077-05/rs
7
A fusion device has MANY major components
Availability required for each component needs to be high
(Table based on information from J. Sheffield et al.)
Component Num
Failure
rate in
hr-1
MTBF in MTTR
for
years
Outage Risk Component
16
5 x10-6
23
Major
failure,
hr
104
MTTR
Fraction of
for Minor failures that
failure, hr are Major
240
0.1
0.098
0.91
8
5 x10-6
23
5x103
240
0.1
0.025
0.97
4
1 x10-4
1.14
72
10
0.1
0.007
0.99
2
100
32
4
1
1
2 x10-4
1 x10-5
2 x10-5
2 x10-4
3 x10-5
1 x10-4
0.57
11.4
5.7
0.57
3.8
1.14
300
800
500
500
72
180
24
100
200
20
-24
0.1
0.05
0.1
0.3
1.0
0.1
0.022
0.135
0.147
0.131
0.002
0.005
0.978
0.881
0.871
0.884
0.998
0.995
3
5 x10-5
72
6
0.1
2.28
Conventional equipment- instrumentation, cooling, turbines, electrical plant ---
0.002
0.05
0.624
0.998
0.952
0.615
ber
Toroidal
Coils
Poloidal
Coils
Magnet
supplies
Cryogenics
Blanket
Divertor
Htg/CD
Fueling
Tritium
System
Vacuum
TOTAL SYSTEM
Availability
DEMO availability of 50% requires:
Blanket availability ~88% and blanket MTBF >11 years.
077-05/rs
8
LIFE – IFE based power producer
 ODS Ferritic
Steel Structural
 PbLi First wall
coolant
 Be multiplier /
moderator
 Mobile particle
(TRISO-like)
fission fuel form
 Flibe coolant /
tritium breeder
9
077-05/rs
Courtesy of W. Meier,
LLNL
LIFE blanket system with PbLi and Flibe
Coolants
Triso-like fuel and MS
Courtesy of W. Meier, LLNL
10
077-05/rs
SABR Design from Georgia Tech – Tokamak
based system with Fusion/Fission blanket
inside the TF coils and vacuum vessel
Courtesy of W. Stacey, GT
Based on ITER size and power levels, and
sodium fast reactor fuels
11
077-05/rs
SABR – All sodium cooled blanket, FW,
divertor based on ODS ferritic steel structure
Courtesy of W. Meier, LLNL
12
077-05/rs
FFTS Concept – Remove the fission blanket completely
outside the fusion driver (access & decoupling), design
for complete fusion core replacement
Courtesy of UT/UCLA
077-05/rs
FFTS– normal conducting, replaceable coils and
current generation structural materials, SFR blanket
Courtesy of UT/UCLA
077-05/rs
Process of the Hybrid Blanket Panel
 Review past reports, earlier reviews, and papers;
particularly focused on recent concepts and
blanket / nuclear technology perspective
 Summarize some representative example
concepts (LIFE, SABR, FFTS)
 Many discussions on concept strategies, potential
benefits, and concerns – Technical judgement
 Writing/revising outcomes of these discussions
and summaries of concepts
 Draft chapter distributed for comments
 Take our lumps at Workshop
 Revise chapter, finalize conclusions
15
077-05/rs
Potential Benefits to Hybrid Blankets: Possibility of
reduced load on the first wall, divertor and plasma
control structures (both in neutrons and surface
heating)
 Lower power plasma operation due to significant energy
multiplication behind the first wall in the blanket.
 Potential economic and availability benefit from this reduced load if
the first wall does not need to be replaced as often or the overall size
of the system is made smaller.
 Potential R&D, cost and development time benefits if materials
requirements in terms of damage (dpa and helium generation) or
operating loads could be reduced in favor of more near term
materials, while still meeting economic performance goals.
 Additionally, if energy in FW, divertor, and other PFC surfaces
becomes expendable (a small percentage of overall system power),
it may be possible with some acceptable economic penalty to use
coolants and temperature regimes most beneficial to their reliability
rather than power conversion performance.
 NOTE: not all proposed hybrid concepts attempt to reduce the wall
16
loads of pure fusion neutrons
077-05/rs
Potential Benefit Compared to Fission Systems –
Subcritical Fission Blanket operation
 Potentially enable the use of a wider range of fission blanket
designs and fuels than may be possible for critical systems,
– Less need for strong negative power reactivity
feedback?
– Larger prompt critical margins
 There may also be fuel cycle benefits related to potential
for increased burn up of fission fuels and transmutation of
more difficult to manage fission fuels when compared to
critical fission systems
(not studied in detail by the blanket panel and conclusions
are deferred to the fuel cycle panel).
17
077-05/rs
Developing hybrids will require substantially the same
types of blanket & materials R&D needed for pure fusion
as well as that needed for new fission fuels & safety.
 The technology readiness for the fission blankets in hybrids is
behind that of the fission analogs
 Development and Qualification of these blanket systems would
require similar development path (recall earlier slide on pure
fusion issues) and integrated test facilities as currently envisioned
in both pure fusion and fission development
 Adapting the fabrication processes for pin/clad type to cores with
more complex toroidal and poloidal geometries in magnetic
fusion or the angular and azimuthal geometries in inertial fusion
 Particles fuels may not be the traditional TRISO fuel used in high
temperature gas reactors, but includes different coating layers
whose fabrication is today unknown.
 Impact on the fuel of magnetic fields (JxB) forces especially during
disruptions and high cycle fatigue associated with the high rep
rate of inertial system is not yet known.
18
077-05/rs
A similar science-based Framework for Fusion Fission
Hybrid Technology Development will be required
Theory/Modeling/Database
Basic
Separate
Effects
Property
Measurement
Multiple
Interactions
Design Codes, Predictive Cap.
Partially
Integrated
Phenomena Exploration
Integrated
Component
•Fusion Env. Exploration Design
Verification &
•Concept Screening
•Performance Verification Reliability Data
Non-Fusion Facilities
(non neutron test stands,
fission reactors and accelerator-based
neutron sources, plasma physics devices)
Experiments in non-fusion facilities are
essential and are prerequisites
Testing in Fusion Facilities is NECESSARY
to uncover unanticipated phenomena,
validate the predictive capability,
establish engineering feasibility and
integration, and qualify components
Testing in Fusion Facilities
077-05/rs
19
Integrated Testing Even More Crucial for
Fusion Fission Hybrids
• FNSF (also called VNS, CTF) a small size, low
fusion power DT plasma device in which
Fusion Nuclear Science and Technology
(FNST) experiments can be performed in the
relevant fusion environment:
1- at the smallest possible scale, cost, and
risk, and
2- with practical strategy for solving the
tritium consumption
3- failure tolerant and designed for fast
replacement
In MFE: small-size, low fusion power can be
obtained in a low-Q (driven) plasma device,
with normal conducting Cu magnets
Equivalent in IFE: reduced target yield (and
smaller chamber radius?)
20
077-05/rs
Whether the development time scale for hybrid is
longer or more rapid than pure fusion can not be firmly
concluded without further extensive analysis.
 Reduced loading on primary fusion structures may reduce risk,
number of testing cycles, or material development requirements
 But the additional complication related to fission functions and
requirements is a concern – achieving RAMI and safety may be
much longer than indicated in the hybrid concepts presented.
 The safety case burden of proof for the hybrid will be greater than
pure fusion given the hazards of the fission blanket,
– Increased likelihood of, and complex approaches required to
mitigate, loss of coolant accidents (sodium vessel not lifetime
component nor low fluence/damage)
– the combined energy sources associated with fusion
(magnets, plasmas) and fission (afterheat, sodium)
– the overall complexity of the system
 Several concepts propose use of ODS Ferritic steels as main
structural material with high damage limits (200 dpa). ODS steels
manufacture and especially joining are still experimental
21
077-05/rs
The ability to meet tritium breeding requirements and
fission fuel transmutation goals must be based on
neutronics analysis including more complete design
 Including time variations coming from fuel and lithium burnup and
reduced reactivity
 Including realistic amounts the structure, coolants, penetrations,
plasma fueling/control systems, etc.
 The strategy of completely removing the fission blanket to a region
outside the TF coils of the fusion device is a paradigm shift from
fusion power plants designs that has several potential advantages,
but detailed implications must be fully analyzed
– power peaking in fission system (magnet system holes)
– access for plasma maintenance systems,
– ability to meet tritium production requirements,
– economics and waste disposal
 The strategy to store large amounts of tritium for later in the burn
cycle is a safety concern and must be fully analyzed
22
077-05/rs
Glaring Omissions




Fission suppressed, fissile fuel production
Differences of other confinement systems
Mobile fuels dissolved in coolants
?
Conclusions
 Blanket/FW/materials area is a key area, the
ultimate feasibility, attractiveness, economics of
the hybrid will depend heavily on these
technological systems.
23
077-05/rs
Blanket Parallel Session
 Speakers
– Bill Stacey – SABR blanket / safety
– Bob Woolley – Dissolved fuels and 2 chamber
concept
– Ralph Moir – fission suppressed fissile fuel
production and dissolved fuels
– Wayne Meier – LIFE Blanket
– Glen Wurden – Other pulsed concepts using
molten salt and the benefits of dissolved fuels
24
077-05/rs
 New slides added and use throughout the
meeting.
 Drafts, not in final form…
25
077-05/rs
Potential Benefits to Hybrid Blankets: Possibility of
reduced load on the first wall, divertor and plasma
control structures due to fission energy multiplication
 Potential cost/time benefits from this reduced load
– if the first wall does not need to be replaced as often or the overall
size of the system is made smaller.
– if materials requirements are reduced (dpa / helium / TM load / low
activation) in favor of more near term materials and test facilities
– if energy in FW/divertor becomes expendable so coolants /
temperature regimes are chosen that are beneficial to reliability
 NOTE: not all proposed hybrid concepts attempt to reduce the wall loads
of pure fusion neutrons but use modest power multiplication to boost
output power
 Some concept pursue this aggressively, either with high keff, low power.
Potential Benefits to Hybrid Blankets: Amplification of
neutron multiplication for tritium breeding
26
077-05/rs
Potential Benefits to Hybrid Blankets: Opening up the
driver space to something that is more easily
maintainable, or technologically simpler from blanket
perspective
 Mirror, others?
 Driver panel must evaluate the potential from physics point-of-view
Potential Benefits to Hybrid Blankets: Potential to operate
in regime of reduced disruptivity and/or reduced
disruption load
 Some concepts have significantly lower current, lower stored energy,
smaller size (can cut both ways)
 Regimes of conservative plasma operations in regards to disruption
frequency and elms
 Reduced wall loads leading to less FW flaking into plasma
27
077-05/rs
Potential Benefit Compared to Fission Systems –
Subcritical Fission Blanket operation
 Potentially enable the use of a wider range of fission blanket
designs and fuels than may be possible for critical systems,
 There may also be fuel cycle benefits related to potential
for increased burn up of fission fuels and transmutation of
more difficult to manage fission fuels when compared to
critical fission systems (not studied in detail by the blanket
panel and conclusions are deferred to the fuel cycle
panel).
28
077-05/rs
Other general conclusions/concerns of blanket
panel
 Developing hybrid blankets will require substantially the same
TYPES of blanket & materials R&D needed for pure fusion as well as
that needed for new fission fuels & safety.
 Integrated testing in a prototype facility remains a serious need
 Whether the development time scale for hybrid is longer or more
rapid than pure fusion can not be firmly concluded without further
extensive analysis and will be concept specific.
 The ability to meet tritium breeding requirements and fission fuel
transmutation goals must be based on neutronics analysis
including more complete design
 Blanket/FW/materials area is a key area, the ultimate feasibility,
attractiveness, economics of the hybrid will depend heavily on
these technological systems.
29
077-05/rs
General conclusions of blanket panel
 The attempt to put near term fixed fuels / existing fission fast
reactor designs inside the fusion vacuum vessel adjacent to the
plasma appears very difficult from refueling, LOCA, fuel or
coolant interactions with magnetic fields and disruptions.
 Mobile fuels may offer benefits to overcome access, geometric
restrictions and fuel damage due to fusion conditions.
– Concerns exist regarding licensing and proliferation in the
current regulatory environment
– Significant past work and designs in fission but not currently
large MS R&D. Is an option considered for a long time in
many fusion systems
30
077-05/rs
Today's discussions on blanket (1)
 The attempt to put near term fixed fuels / existing fission fast
reactor designs inside the fusion vacuum vessel adjacent to
the plasma appears very difficult
– Access for shuffling the fixed fuel is extremely restricted
– LOCAs can not be excluded and afterheat removal
from fixed fuel will require active systems
– Proximity to plasma disruptions could damage fuels
 Fission suppressed, fissile fuel production
– Has additional benefit of fuel production. Essentially
requires equivalent fusion blanket system / materials as
pure fusion
– Need for this mission may only materialize down the
road (later half of century), but this may be the right
time scale for hybrid development anyway.
– Proliferation risk
31
077-05/rs
Today's discussion on blanket (2)
 Mobile fuels offer benefits to overcome hybrid access, geometric
restrictions and fuel damage due to fusion conditions
 TRISO-like fuels with 99% burnup proposed for LIFE use steel outer
shell to contain gases. Other possible fuel failure mechanisms
expected at high burnup weren’t discussed
 Dissolved fuels in molten salts proposed for several concepts
– Pulsed fusion concepts in IFE, MTF, Zpinch already propose MS use,
some with thick liquid walls. Requirements on fusion system not
reduced by hybrid mission
– Recent actinide burning analysis by Ed Chang/Y. Gohar/M. Ubeyli
– Advantages: on-line control, no thermomechanical fuel damage,
overcome geometrical restrictions, high burnup, reduced MHD
issues
– Main concerns: licensing and proliferation requires strict accounting
for fuel, additional contamination from accidental spills, others??
Why last of GENIV?
32
077-05/rs