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UKAEA
Creep Fatigue Interaction for Nuclear Fusion
4 October 2018
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To lead the commercial development of fusion power and related technology and position the UK as a leader in sustainable nuclear energy
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UKAEA’s mission statement
Nuclear Fusion
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Fusion Reaction on Earth
Deuterium
TritiumNeutron
Helium
+ energy (17.6MeV)
Deuterium
TritiumNeutron
Helium
+ energy (17.6MeV)
Deuterium supplies are extensive
Tritium to be bred from lithium through neutron reactions6Li + n → 4He + T
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The Tokamak Concept
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Toroidal field coilPrimary transformer circuit
Secondary plasma currentPoloidal magnetic field
Toroidal magnetic field
Resultant helical magnetic field
EU-Fusion Power Roadmap
JETJoint European Torus ITER DEMO
The EU fusion community is pursuing an aggressive programme of research to allow the near-term realisation of a
demonstration magnetic confinement fusion power plant (DEMO).
Physics Oriented
Technology
Oriented
Confinement, H-mode scaling, ITER-like wall
Burning plasma, current drive steady state (long
pulse), disruption control, edge control)
Superconducting magnets, fueling, heating/CD,
test blanket modules
Electricity generation (balance of plant), materials and component lifetime, closed fuel cycle, remote
maintenance, availability
Technology & Materials Programme
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Fusion operational limits
“..known, knowns .. known, unknowns (and) unknown, unknowns…1”
Fusion will require a pragmatic approach and accepted of risks
1 Part of speech by Donald Rumsfeld in 2002
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The Blanket Challenge
▪ To shield the vacuum vessel and the superconducting magnets
▪ To capture the neutrons to “breed” tritium fuel
▪ To turn the kinetic energy from neutrons into heat energy for electrical power production
▪ High structural integrity to permit long operational lifetimes (~years)
▪ High operational temperature to promote high thermodynamic efficiencies
Functions
Requirements
Power densities: >1MWm-2 steady state
Cyclic operation: >15,000 cycles anticipated in DEMO
Irradiation: ~10dpa/fpy via 14MeV neutrons
~12appm/dpa Helium production
Lifetime: >5fpy in order to assure availability
Temperature: >500℃ for high thermodynamic efficiencies
Power plant solution demands innovation:
Materials, Engineering, Physics
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Using steel in the blanketTritium permeation – issues and
compatibility with permeation
barriers
He and H production
Water/He compatibility
Matching temperature for BoP
Codes and StandardsCompatibility with vacuum
conditions
Tritium trapping in damaged
material
Total mass
Performance on cyclic
operational plantCompatibility with remote
handling
Manufacturing to acceptable
tolerances
Extreme heat flux at the surface
Accident tolerance: Loss of
coolant, temperature spikes,
ELM
Oxidation and plasma erosion
tolerance Total costs
Compatibility with diagnostics
Compatibility with heating and
current drive components
Meeting lifetime requirements
Effects of high magnetic field on
propertiesMeeting reduced activation
requirements
Effects of ELMs inducing
magnetic swings
Enabling of in-service
inspection techniques
Beryllium and Lithium pebble
compatibility
Liquid lithium and lead
compatibilityJoining methods
Effects of neutrons
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Using steel in the blanketTritium permeation – issues and
compatibility with permeation
barriers
He and H production
Water/He compatibility
Matching temperature for
BoP
Codes and StandardsCompatibility with vacuum
conditions
Tritium trapping in damaged
material
Total mass
Performance on cyclic
operational plantCompatibility with remote
handling
Manufacturing to acceptable
tolerances
Extreme heat flux at the surface
Accident tolerance: Loss of
coolant, temperature spikes,
ELM
Oxidation and plasma erosion
tolerance Total costs
Compatibility with diagnostics
Compatibility with heating and
current drive components
Meeting lifetime requirements
Effects of high magnetic field on
propertiesMeeting reduced activation
requirements
Effects of ELMs inducing
magnetic swings
Enabling of in-service
inspection techniques
Beryllium and Lithium pebble
compatibility
Liquid lithium and lead
compatibilityJoining methods
Effects of neutrons
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Creep Fatigue Interaction
Creep fatigue is the life limiting factor in
proposed DEMO operation
• Material: EUROFER97 (Ferritic-
martensitic steel)
• Operating temperature: ~500⁰C
• Operational stresses: ~100MPa
• Operating cycle: Ramp up with ~2hr hold
• Number of cycles: ~40,000
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Data gathering -> testing
• Issues to overcome:
– How to accelerate the testing
– Tension / compression testing
– Incorporating heating and vacuum
– Dealing with small sized samples
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Data gathering -> testing
• Phoenix hydraulic testing rigs:
– Creep and fatigue
– IR heating
– Bespoke grips for small samples
• Future rigs
– Incorporate vacuum
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Structural integrity case
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DEMO is a First of Kind Engineering Project Success/Failure based on sufficient:
component performance (safety & operational)lifetime
Verification of structural integrity at design phase and through life are pivotal!
Courtesy UKAEA
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FusionUKAEA is at the vanguard of fusion research; we work to help mankind harness this power.
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