page 1 of 14 Reflections on the energy mission and goals of a fusion test reactor ARIES Design Brainstorming Workshop April 2005 M. S. Tillack

page 2 of 14 “ITER is the experimental step between today’s studies of plasma physics and tomorrow’s electricity-producing fusion power plants” ( ) Is this credible?

page 3 of 14 Fusion energy development should be guided by requirements for a fusion energy source  No public evacuation plan is required  Generated waste can be returned to environment or recycled in less than a few hundred years ( i.e., not geological time-scales)  No disturbance of public’s day-to-day activities  No exposure of workers to a higher risk than other power plants  Closed tritium fuel cycle on site  Ability to operate at partial load conditions (50% of full power)  Ability to efficiently maintain power core for acceptable plant availability  Ability to operate reliably with less than 0.1 major unscheduled shut-down per year Above requirements must be achieved consistent with a competitive life-cycle cost-of-electricity goal.

page 4 of 14 Existing and planned facilities fail to address essential features of a fusion energy source

page 5 of 14 Existing and planned facilities fail to address essential features of a fusion energy source

page 6 of 14 ITER/ FIRE ARIES “next step” Starlite

page 7 of 14 An experimental power reactor is needed to establish the credibility of fusion as a competitive ENERGY SOURCE Essential features:  Power plant relevant materials  Full nuclear operations  Reasonable lifetime fluence (1-10 MW-yr/m 2 )  Closed fuel cycle operation  Etc  Fill these in…  Etc Parameters do not need to replicate a power plant; rather, the device should be optimized to meet the requirements of a device on the pathway to a power plant.

page 8 of 14 Our study should emphasize holistic R&D needs and their design implications Holistic : relating to or concerned with wholes or with complete systems rather than with the analysis of, treatment of, or dissection into parts. Plasma Blankets Divertors Magnets Vacuum vessel Power management Reactor control Fuel management Maintenance Safety Waste

page 9 of 14 Examples of holistic issues for system studies of experimental power reactors Thermal power management: Demonstrate divertor power and particle handling, extraction of power core high-grade heat, nuclear performance of ancillary equipment (rf, magnets, etc. ) Fuel management: Demonstrate “birth to death” tritium management in a closed loop with self-sufficient breeding. Safety: Demonstrate public and worker safety of the integral facility, capturing system to system interactions. Plant operations: Establish the operability of a fusion energy facility, reliability of components, inspectability and maintainability of a power plant relevant tokamak. Flexibility: Explore alternative operating modes and power core technologies with high duty cycle, but flexible operations.

page 10 of 14 Thermal power management: Demonstrate divertor power and particle handling, extraction of power core high-grade heat, nuclear performance of ancillary equipment (rf, magnets, etc.) 1-f rad,div P fusion P neutron PP Divertor First wall P rad,chamb P div 80% 20% P cond P rad,div f rad,core 1-f rad,core f rad,div F div,peak

page 11 of 14 Fuel management: Demonstrate “birth to death” tritium management in a closed loop with self-sufficient breeding. inventory pumps breeder coolant breeder processing coolant processing vacuum processing fueling D+T D+T+  n T Fuel processing

page 12 of 14 Plant operations: Establish the operability of a fusion energy facility, reliability of components, inspectability and maintainability of a power plant relevant tokamak. If power plant blankets can be replaced in 1-2 months, then a test reactor blanket should be replaceable too.

page 13 of 14 Challenges for an ARIES interface with domestic energy R&D programs The US is not actively pursuing energy technologies for fusion. EU and Japan have serious technology programs; coordination between ARIES and international activities (including the “ITER broad approach”) will be essential. R&D R&D needs Design This part is absent

page 14 of 14 Summary The time is right to explore remaining facilities on the path to fusion energy ARIES is accepted as an appropriate venue to explore fusion energy, even in an era emphasizing “basic science”. Any device on the path to fusion energy should advance features that lead to a commercially attractive end product. A strength of the ARIES team is our integrated “holistic” approach to design studies. Key device features and mission elements should reflect overarching goals of fusion energy. The mission should complement existing and planned facilities, including consideration of the “ITER broad approach”