077-05/rs 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 Summary
of Preliminary Conclusions of the ReNeW Fusion/Fission Hybrid
Blanket Panel Slide 2 077-05/rs 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
The Hybrid Blanket Panel Slide 3 077-05/rs 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 Outline Slide 4 077-05/rs 4 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)
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 Fusion Nuclear Science and Technology plays
the KEY role Slide 5 077-05/rs 5 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 4. Tritium Processing Systems 5. Remote
Maintenance Components 6. Heat Transport, Power Conversion Systems
Other Systems / Components affected by the Nuclear Environment:
ARIES-AT FNST COMPONENTS Slide 6 077-05/rs 6 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.HYBRID -- Transmutation, Energy and Neutron
multiplication, and/or Fissile Fuel Production Minimize parasitic
absorption. Moderation / transmission of fusion neutrons to fission
fuel n Plasma p np n np Blanket n ALL FUSION NEUTRONS NEEDED FOR
BREEDING TRITIUM, STRONG MULTIPLICATION NEEDED FOR HYBRID Slide 7
077-05/rs 7 1.D-T fuel cycle tritium self-sufficiency in a
practical system 2.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 electrically- conducting 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 PFCs in the
fusion environment 10.System configuration and Remote maintenance
with acceptable machine down time Summary of Top- Level Technical
Issues for Fusion Nuclear Science and Technology Slide 8 077-05/rs
8 A fusion device has MANY major components Availability required
for each component needs to be high DEMO availability of 50%
requires: Blanket availability ~88% and blanket MTBF >11 years.
(Table based on information from J. Sheffield et al.) Slide 9
077-05/rs 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 Courtesy of W. Meier, LLNL Slide 10 077-05/rs LIFE
blanket system with PbLi and Flibe Coolants 10 Courtesy of W.
Meier, LLNL Triso-like fuel and MS Slide 11 077-05/rs SABR Design
from Georgia Tech Tokamak based system with Fusion/Fission blanket
inside the TF coils and vacuum vessel 11 Based on ITER size and
power levels, and sodium fast reactor fuels Courtesy of W. Stacey,
GT Slide 12 077-05/rs SABR All sodium cooled blanket, FW, divertor
based on ODS ferritic steel structure 12 Courtesy of W. Meier, LLNL
Slide 13 077-05/rs FFTS Concept Remove the fission blanket
completely outside the fusion driver (access & decoupling),
design for complete fusion core replacement Courtesy of UT/UCLA
Slide 14 077-05/rs FFTS normal conducting, replaceable coils and
current generation structural materials, SFR blanket Courtesy of
UT/UCLA Slide 15 077-05/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 Slide 16 077-05/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 loads of pure
fusion neutrons 16 Slide 17 077-05/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 Slide 18 077-05/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 Slide 19 077-05/rs 19 Theory/Modeling/Database Basic
Separate Effects Multiple Interactions Partially Integrated
Property Measurement Phenomena Exploration Non-Fusion Facilities A
similar science-based Framework for Fusion Fission Hybrid
Technology Development will be required Design Codes, Predictive
Cap. Component Fusion Env. Exploration Concept Screening
Performance Verification Design Verification & Reliability Data
Testing in 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 Slide 20 077-05/rs 20 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?) Slide 21 077-05/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 Slide
22 077-05/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 Slide 23 077-05/rs Glaring Omissions Fission
suppressed, fissile fuel production Differences of other
confinement systems Mobile fuels dissolved in coolants ?
Blanket/FW/materials area is a key area, the ultimate feasibility,
attractiveness, economics of the hybrid will depend heavily on
these technological systems. 23 Conclusions Slide 24 077-05/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 Slide 25
077-05/rs New slides added and use throughout the meeting. Drafts,
not in final form 25 Slide 26 077-05/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. 26 Potential Benefits to Hybrid Blankets: Amplification
of neutron multiplication for tritium breeding Slide 27 077-05/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 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 Potential Benefits to Hybrid
Blankets: Potential to operate in regime of reduced disruptivity
and/or reduced disruption load Slide 28 077-05/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 Slide 29 077-05/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 Slide 30 077-05/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 Slide 31 077-05/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 Slide 32
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 werent
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 ?
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