TWG goals, approach and outputs

1. TWG goals, approach and outputs M. S. Tillack ARIES Project Meeting 13 December 2007

2. Topics • Review of TWG tasks and schedules • FESAC v. ARIES • Discussion of “R&D planning” • Discussion of TWG outputs

3. ARIES Tasks Decision to commercialize fusion Parametric trade studies External advisory committee 2 1 TWG’s: Power management Tritium management Plant operations T W G R&D needs and priorities Design requirements 3 4 Tokamak line of R&D Experimental power reactor 5 ARIES-AT Demo ARIES-AT Nuclear tokamaks ITER ARIES Study Outcomes: 1. Guidelines for fusion development 2. Sensitivity study results 3. R&D document, methodology 4. Preconceptual design requirements 5. Preconceptual design report Non-nuclear tokamaks Other R&D and facilities

4. TWG Schedule Jun 2007 Sep 2007 Dec 2007 Mar 2008 Jun 2008 Sep 2008 TWG planning cancelled UAC mtgs Formulation of requirements Definition of requirements Conceptual design activity Conceptualdesign process R&D existing status and needs Evaluation of R&D plans/options R&D planning (Interim report) Final report Documentation ARIES mtgs

5. FESAC: what they did(see http://www.ofes.fusion.doe.gov/fesac.shtml) • Made the case for energy technology R&D • Made the case for bold new initiatives and facilities • Derived R&D needs mainly in a “roll forward” approach • “we’ve done xyz, so what do we do next?” • Assumed no “reactor-scale” device between ITER & Demo • Posed a large set of “issues” and defined them in detail • >200 pages • “identify the scientific questions and technical challenges” • Included “alternate concepts” (liquid divertor, stellarator)

6. FESAC: what they did not do • Derive R&D needs from the customer perspective (roll back perspective) • Define what constitutes “resolution” of an issue • Develop metrics to evaluate and prioritize research, and milestones to judge progress • Comment on whether the current DOE Office of Science strategy (ITER–Demo) is credible, or assess any of the current proposals for next-step machines

7. ARIES v. FESAC: what is our role? • Provide metrics to prioritize research and milestones to judge progress relative to the end goal • Define levels of performance, or achievement, that are adequate to declare success in the R&D program • i.e., define what constitutes “resolution” of an issue • Apply roll-back “ARIES approach” • Define performance goals based on attractive fusion plants • Describe R&D needs to demonstrate commercial viability • Use ARIES designs for reference, as needed In a nutshell, we need to develop a technical methodology for evaluating R&D proposals

8. In order to define an R&D program, we need a set of “ground rules” • Discussions with team members uncovered differences in assumptions • There is not one unique R&D program we can envision. Upfront decisions are needed to formulate an R&D plan, e.g.: • Downselection – how, when, who? • Portfolio approach – is it our job to pick a winner? now? • Level of detail – broad R&D areas vs. individual tests • Aggressiveness – cost, risk, urgency? • Timing relative to ITER and other national and international programs • “Reality constraints” – politics, international collaborations, … • Roles of ARIES, DOE programs, IAC, industry • Is it our job to define R&D programs? • We are not the ones who finally will select and implement R&D. Our primary role is to provide guidance, options, methodologies, trade-offs, etc.

9. Instead of trying to define one R&D program, we should concentrate on providing a methodology for evaluating R&D • We still need to define the issues, because resolution of issues is at the heart of the evaluation • Keeping issues “broad” will make metrics more tractable (examples on next slide) and more relevant to an integrated systems approach • We can (should?) apply the methodology to example cases, such as the PbLi blanket R&D plan, ITER, or a next-step machine(s)

10. Examples of metrics based on issues • For power conversion • Operating temperature (relates to efficiency, ability to produce H2) • Power flow control, uncertainty in power flows, peaking factors • Heat flux and total heat (prototypical gradients, scale) • Operating lifetime (relates to reliability, availability) • Degree of system integration (synergistic effects) • For tritium • Breeding ratio, uncertainty in TBR • Inventory, uncertainty in inventory • Leakage from plant under normal, off-normal conditions • For operations • Disruption frequency

11. Examples of milestones based on metrics • For power conversion • Operating temperature (relates to efficiency, ability to produce H2) • Water limit (>35%), <350˚ C • Steel limit (>45%), <500˚C • Ultimate goal (>55%), >800˚C • Operating lifetime (relates to reliability) • Beginning of life • Infant mortality • Operating life • End-of-life • Power flows • Peaking factors <2 • Control/uncertainty better than 10% • Demonstration of low power operating conditions (50%) • Heat flux and total heat in tests (prototypical gradients, scale) • Degree of system integration in tests (synergistic effects)

12. Timely results are needed • Results needed from TWG’s now • Define the metrics, current status and gaps • Define milestones and evaluation points (phased approach) • TWG leaders should do this immediately!!! • Documentation will provide background and technical justification • Document • As a minimum, TWG leaders should provide an outline and authors immediately!!! • Interim report doesn’t have to be long, just good: quality over quantity