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A methodology for evaluating progress toward an attractive fusion energy source. M. S. Tillack, L. M. Waganer. US/Japan Workshop on Fusion Power Plant Studies 5-7 March 2008. Why do we need a methodology for evaluating progress?.
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A methodology for evaluating progress toward an attractive fusion energy source M. S. Tillack, L. M. Waganer US/Japan Workshop on Fusion Power Plant Studies 5-7 March 2008
Why do we need a methodology for evaluating progress? • Metrics are needed to quantify progress and the value of fusion facilities • In addition to individual facilities, a method is needed to compare alternative pathways (using cost, risk,benefit) in an objective and quantitative manner • DOE and the Greenwald subpanel of FESAC (”Priorities, gaps and opportunities: towards a long-range strategic plan for magnetic fusion energy”) also recognizes the need for metrics (http://www.ofes.fusion.doe.gov/fesac.shtml) ?
The EU is also pursuing an approach to evaluate current technology readiness
The US Government Accountability Office (GAO) encourages “a disciplined and consistent approach for measuring technology readiness” • Technology Readiness Levels represent a systematic methodology that provides an objective measure to convey the maturity of a particular technology. • They were originally developed by NASA, but with minor modification, they can be used to express the readiness level of just about any technology element. • The Department of Defense has adopted this metric to evaluate the readiness levels of new technologies and guide their development to the state where they are considered “Operationally Ready”. • The Department of Energy has adopted the use of TRL’s in their evaluation of the GNEP program. • Can fusion energy benefit from this approach to develop the technologies needed for Demo?
Characteristics of TRL’s, cont’d. GAO recommendation: “Direct DOE Acquisition Executives to ensure that projects with critical technologies reach a level of readiness commensurate with acceptable risk – analogous to TRL 7 – before deciding to approve the preliminary design and commit to definitive cost and schedule estimates, and at least TRL 7 or, if possible, TRL 8 before committing to construction expenses.
Example of TRL’s for GNEP*:fast reactor spent fuel processing
Example of TRL’s for GNEP*, continued:fast reactor spent fuel processing *Global Nuclear Energy Partnership
How can we apply this to fusion energy? • Use criteria from utility advisory committee to derive issues (roll back) • Connect the criteria to fusion-specific (design independent) technical issues and R&D needs • Describe Technology Readiness Levels for the key issues • Define the end goal (design) in enough detail to evaluate progress • Evaluate status, gaps, facilities and pathways
1 Utility Advisory Committee“Criteria for practical fusion power systems” J. Fusion Energy 13 (2/3) 1994. • Have an economically competitive life-cycle cost of electricity • Gain public acceptance by having excellent safety and environmental characteristics • No disturbance of public’s day-to-day activities • No local or global atmospheric impact • No need for evacuation plan • No high-level waste • Ease of licensing • Operate as a reliable, available, and stable electrical power source • Have operational reliability, high availability • Closed, on-site fuel cycle • High fuel availability • Capable of partial load operation • Available in a range of unit sizes End-user (Customer) Pathways Power plant requirements Demo R&D needs R&D and facilities definition Power plant designs
2 The criteria for attractive fusion suggest three categories of technology readiness • Economic Power Production • Control of plasma power flows • Heat and particle flux handling • High temperature operation and power conversion • Power core fabrication • Power core lifetime • Safety and Environmental Attractiveness • Tritium inventory and control • Activation product inventory and control • Waste management • Reliable Plant Operations • Plasma diagnosis and control • Plant integrated control • Fuel cycle control • Maintenance 12 top-level issues
The intent is to be comprehensive based on functions rather than physical elements • Economic Power Production • Control of plasma power flows • Heat and particle flux handling • High temperature operation and power conversion • Power core fabrication • Power core lifetime Power deposition Power flows Power conversion
3 Example: High Temperature Operation
4 An evaluation of readiness requires identification of an end goal • For the sake of illustration, we are considering Demo’s based on mid-term and long-term ARIES power plant design concepts, e.g. • Diverted, high confinement mode, tokamak burning plasma • Low-temperature or high-temperature superconducting magnets • He-cooled W or PbLi-cooled SiC divertors • PbLi-cooled SiC or dual-cooled He/PbLi/ferritic steel blankets • 800˚C (or higher) coolant outlet temperature with high-efficiency Brayton cycle • Advanced power core fabrication processes • Efficient autonomous maintenance
5 Example evaluation: High temperature operation and power conversion (DCLL) • Concept development is largely completed. Limited data on ex-vessel parts of power conversion system (e.g., HX) • To achieve TRL4: Need full loop operation at high temperature in a laboratory environment • This is typical of many issues; some are more advanced, but most are stuck at TRL=3
Summary • The TRL approach has significant advantages • Objective metrics for entire range of development • Systematic for all plant elements • Integrated approach • Widely accepted (within the US government) • We have shown that the TRL approach can be applied to fusion energy • The ARIES pathways study will develop a complete methodology and evaluate example concepts • TRL’s have been defined for all of the key issues • We are preparing to run through an example evaluation of Demo concepts • Analysis of facilities will follow