Issues, Development, and Role of Next Step Fusion Nuclear Facility (FNF) and ITER TBM FNST Meeting, UCLA August 12-14, 2

1. BACKUP SLIDESFNST Issues, Development, and Role ofNext Step Fusion Nuclear Facility FNF(VNS/CTF/FDF, etc.) and ITER TBM FNST Meeting, UCLA August 12-14, 2008 Mohamed Abdou

2. Quantification of Test Requirements General Observations of FINESSE Study Results • In many cases, a true integrated test in the strictest sense cannot be performed under significantly scaled-down conditions for certain parameters (e.g., power density, surface heat load, geometry) • Under scaled-down environmental conditions, the function of an integrated test module has to be divided into two or more “act-alike” tests. Each act-alike test emphasizes a group of issues/phenomena. • While an overlap among the various act-alike tests can be included to account for certain interfaces, a concern about possibly missing some phenomena remains. • Perfect quantitative engineering scaling is not possible because it requires complete quantitative models for all (including interactive) phenomena. • If fusion testing will have to be carried out under scaled-down conditions, then: - Engineering scaling needs to continue to be nourished as a key technical discipline in fusion. - The need for a more thorough understanding of phenomena and more analytical modeling will become more critical.

3. How Many Modules/SubmodulesNeed to Be Tested For Any Given One Blanket Concept? • Never assume one module, because engineering science for testing shows the need to account for: 1. Engineering Scaling 2. Statistics 3. Variations required to test operational limits and design/configuration/material options • US detailed analysis indicates that a prudent medium risk approach is to test the following test articles for any given One Blanket Concept: • One Look-Alike Test Module • Two Act-Alike Test Modules • (Engineering Scaling laws show that at least two modules are required, with each module simulating a group of phenomena) • Four supporting submodules (two supporting submodules for each act-alike module to help understand/analyze test results) • Two variation submodules (material/configuration/design variations and operation limits) These requirements are based on “functional” and engineering scaling requirements. There are other more demanding requirements for “Reliability Growth” (See separate section on this)

4. Neutron Wall Load Requirements Importance Neutron wall load is a primary source of both heating and nuclear reactions in the blanket Bulking heating Surface heating Reaction rate (e.g., tritium production) Fluence Neutron wall load requirements determined by: Engineering scaling requirements (conclusion: should not scale down by more than a factor of 2-3 Tradeoffs between device availability and wall load for a given testing fluence and testing time Wall Load and Availability Required to Reach 6 MW•y/m2 Goal Fluence in 12 Calendar Years For pulsed plasma operation, this becomes the product of availability and plasma duty cycle. Therefore, at any given wall load, higher availability would be required.

5. Importance of Steady State Operation for Nuclear Testing • To substantially increase the capability for meaningful nuclear technology testing • To reduce the failure rate and improve the availability of the testing device - Many papers and presentations on this topic from the last 20 years. It is well understood and accepted(see, for example, www.fusion.ucla.edu/abdou)

6. Effects of Pulsed Plasma Operation on Nuclear Technology Testing Time-Dependent Changes in Environmental Conditions for Testing Nuclear (volumetric) heating Surface heating Poloidal magnetic field Tritium production rate Result in Time-Dependent Changes and Effects in Response of Test Elements that: Can be more dominant than the steady-state effects for which testing is desired Can complicate tests and make results difficult to model and understand Examples of Effects Thermal conditions Tritium concentration profiles Failure modes/fracture mechanism Time to reach equilibrium

7. Recommended COT for FNT: 1-2 weeks COT Requirements Test Schedule Issues It is desirable to complete a test campaign before the machine is shut down for a significant period of time The objective of design/test/fix iterative program requires timely data acquisition as input to redesign and construction of new test modules. It is therefore desirable to complete test campaigns as quickly as possible. Requirements on Environmental Control The level of control over conditions within test modules and ancillary systems during shutdown is uncertain.

8. Device Fluence vs Test Module Fluence • Must make a distinction between: • Fluence achievable at test module ( modules will fail and will be replaced. Module Fluence is the “cumulative” experience accumulated on successive test articles, in “reliability growth” terminology) • Test facility “lifetime fluence” (The device itself will need to have a longer lifetime than the test articles. The blanket is an exception because it is the “object of testing”, depending on testing strategy) • Benefits to FNT testing as a function of neutron fluence have been recognized: • Many issues show continuous increase in benefits at higher fluences • Some issues show distinct fluence regions of highest benefit • There is inevitably a long period of fail/replace/fix for test modules • Time required to perform the three testing stages: The reliability growth testing phase is the most demanding on fluence requirements.

9. Testing Fluence In this study, we derive fluence directly for each of the three stages of fusion testing Stage I: Scoping (~ 0.1 - 0.3 MW • y/m2) Just enough time to explore environment, develop instrumentation, and get initial data Stage II: Concept Verification (1-3 MW • y/m2) 1 MW • y/m2 is barely enough to establish engineering feasibility (~10% of minimum life) Stage III: Engineering Development & Reliability Growth (4-6 MW • y/m2) This fluence is derived from detailed analysis of reliability growth testing

10. Reference: M. Abdou et. al., "FINESSE: A Study of the Issues, Experiments and Facilities for Fusion Nuclear Technology Research & Development, Chapter 15 (Figure 15.2-2.) Reliability Development Testing Impact on Fusion Reactor Availability", Interim Report, Vol. IV, PPG-821, UCLA,1984. It originated from A. Coppola, "Bayesian Reliability Tests are Practical", RADC-TR-81-106, July 1981. “Reliability Growth” Upper statistical confidence level as a function of test time in multiples of MTBF for time terminated reliability tests (Poisson distribution). Results are given for different numbers of failures. Example, To get 80% confidence in achieving a particular value for MTBF, the total test time needed is about 3 MTBF (for case with only one failure occurring during the test). TYPICAL TEST SCENARIO

11. Achievable DEMO and Blanket System Availabilities (for a given confidence level) depend on: • Testing Fluence at the Blanket Test Module • Number of test modules • Achievable Mean Time to Replace (MTTR) for Blankets

12. Findings of Testing Fluence Requirements on Achievable Reactor Availability Analyses • Achieving a “ cumulative” fluence of ~ 5-6 MW • y/m2 at the test modules with ~ 6-12 test modules is crucial to achieving DEMO reactor availability on the 40% to 50% range with 90% confidence, • Achieving DEMO reactor availability of 60% with 90% confidence may not be possible for any practical blanket test program, • The mean downtime (MTTR) to recover (or replace) from a random failure in the blanket must be on the order of one week or less in order to achieve the required blanket and reactor system availabilities, and • Determining (and shortening) the length of the MTTR (how long it takes to replace a failed blanket module) must be by itself one of the critical objectives for testing in fusion facilities (e.g. in CTF).

13. Level of Confidence based on Figure 15-2.2 in "FINESSE: A Study of the Issues, experiments and Facilities for Fusion Nuclear Technology Research & Development, Chapter 15 Reliability Development Testing Impact on Fusion Reactor Availability", Interim report, Vol. IV, PPG-821, UCLA, 1984. Obtainable Blanket System Availability with 50% Confidence for Different Testing Fluences and Test Areas MTTR = 1 month 1 failure during the test 80 blanket modules in blanket system Experience factor =0.8 Neutron wall load = 2 MW/m2

14. Device Surface Area Requirements No. of Modules per Specific Design Concept Need for Engineering Scaling and Statistics. A large number of test modules lead to a faster reliability growth and a higher precision level. Full scale test preferable There are many problems that were solved only after setting up a full scale test. There are also many problems that surfaced only in the full scale test but did not show in the reduced scale. Account for neutron flux spatial variation in poloidal direction. If each module first wall area is about 1 m2 Test area required = (6 – 12) x A (for engineering scaling) m2 per concept. If test 3 concepts, use 6 modules per concept; or 2 concepts use 12 modules per concept. Total test area at the first wall required: > 10 m2

15. Level of Confidence Obtainable for Different Testing Scenarios Neutron wall load = 2 MW/m2 MTBF per module = 26 years Experience factor = 0.8 (*test fluence of 0.1 MWyr/m2 is too low to consider) Note • Assuming that the reactor has 16 sectors, 80 blanket modules (each module is about 1(toroidal) x 8 (poloida) m2). “Engineering scaling” is applied to the test article design in order to have meaningful data extrapolated from a 0.5 m2 • The irradiation effects on material properties are not considered in the estimation. • Level of Confidence based on Figure 15-2.2 in "FINESSE: A Study of the Issues, experiments and Facilities for Fusion Nuclear Technology Research & Development, Chapter 15 Reliability Development Testing Impact on Fusion Reactor Availability", Interim report, Vol. IV, PPG-821, UCLA, 1984.

16. The base machine includes 10 major components. CTF FW area 100 m2 with 64 blanket modules Demo (ITER like FW area 680 m2 and 440 blanket modules) Lifetime of Demo FW/blanket 10 years Reliability/Availability is a challenge to fusion, particularly FW/blanket, development • Fusion System has many majorcomponents (TFC, PFC, plasma heating, vacuum vessel, blanket, divertor, tritium system, fueling, etc.) • All components except the reactor core (FW/blanket) will have reliability data from ITER and other facilities • The reliability requirements on the FW/Blanket are most challenging and pose critical concerns (due to a large number of modules). These must be seriously addressed as an integral part of the R&D pathway to DEMO. • Predicting Achievable MTBF (mean-time-between-failure) requires real data from integrated tests in the fusion environment. 3 Availability decreases due to the number of module increases 1 2 1 Availability increases due to improved base machine availability 2 Availability increases due to a shortened MTTR for blanket 3

17. Reliability/Availability is a challenge to fusion, particularly blanket/PFC, development • Fusion System has many majorcomponents (TFC, PFC, plasma heating, vacuum vessel, blanket, divertor, tritium system, fueling, etc.) - Each component is required to have high availability • All systems except the reactor core (blanket/PFC) will have reliability data from ITER and other facilities • There is NO data for blanket/PFC (we do not even know if any present blanket concept is feasible) • Estimates using available data from fission and aerospace for unit failure rates and using the surface area of a tokamak show: PROBABLE MTBF for Blanket ~ 0.01 to 0.2 yr compared to REQUIRED MTBF of many years Need Aggressive “Reliability Growth” Program We must have an aggressive “reliability growth” program for the blanket / PFC (beyond demonstrating engineering feasibility) 1) All new technologies go through a reliability growth program 2) Must be “aggressive” because extrapolation from other technologies (e.g. fission) strongly indicates we have a serious CHALLENGE

18. Conclusions on Blanket and PFC Reliability Growth • Blanket and PFC tests in ITER alone cannot demonstrate DEMO availability higher than 4% • Blanket and PFC testing in VNS (CTF) allows DEMO blanket system and PFC system availability of > 50%, corresponding to DEMO availability > 30% Recommendations on Availability/Reliability Growth Strategy and Goals - Set availability goal for initial operation of DEMO of ~ 30% (i.e. defer some risk) - Operate CTF and ITER in parallel, together with other facilities, as aggressively as possible - Realize that there is a serious decision point with serious consequences based on results from ITER and CTF • If results are positive proceed with DEMO • If not, then we have to go back to the drawing board

19. Demo Definition Previous US system and planning studies and the FESAC Plan for Development of Fusion Energy in 2003 identified general goals and features of DEMO. Below are relevant quotes from the FESAC 2003 Plan: • The goal of the plan is operation of a US demonstration power plant (Demo), which will enable the commercialization of fusion energy. The target date is about 35 years. Early in its operation the Demo will show net electric power production, and ultimately it will demonstrate the commercial practicality of fusion power. It is anticipated that several such fusion demonstration devices will be built around the world. In order for a future US fusion industry to be competitive, the US Demo must: • be safe and environmentally attractive, • extrapolate to competitive cost for electricity in the US market, as well as for other applications of fusion power such as hydrogen production, • use the same physics and technology as the first generation of competitive commercial power plants to follow, and • ultimately achieve availability of ~ 50%, and extrapolate to commercially practical levels.

20. Demo Performance Parameters and Characteristics

21. Comparison of Key Blanket Testing Parameters *Plasma duty cycle = burn time/(burn time + dwell time)

22. Process Time Constant Flow Solid breeder purge residence time Coolant residence time Thermal Structure conduction (5-mm metallic alloys) Structure bulk temperature rise 5 mm austenitic steel / water coolant 5 mm ferritic steel / helium coolant Solid breeder conduction Li2O (400 to 800ºC) 10 MW/m3 1 MW/m3 LiAlO2 (300 to 1000ºC) 10 MW/m3 1 MW/m3 Solid breeder bulk temperature rise Li2O (400 to 800ºC) 10 MW/m3 1 MW/m3 LiAlO2 (300 to 1000ºC) 10 MW/m3 1 MW/m3 Tritium Diffusion through steel 300ºC 500ºC Release in the breeder Li2O 400 to 800ºC LiAlO2 300 to 1000ºC 6 s 1 to 5 s 1 to 2 s ~1 s 5 to 10 s 30 to 100 s 300 to 900 s 20 to 100 s 180 to 700 s 30 to 70 s 80 to 220 s 10 to 30 s 40 to 100 s 150 days 10 days 1 to 2 h 20 to 30 h Table XX.* Characteristic Time Constants in Solid Breeder Blankets * From Fusion Technology, Vol. 29, pp 1-57, January 1996

23. Process Time Constant Flow Coolant residence time First wall (V=1 m/s) Back of blanket (V=1 cm/s) Thermal Structure conduction (metallic alloys, 5mm)   Structure bulk temperature rise Liquid breeder conduction Lithium Blanket front Blanket back LiPb Blanket front Blanket back Corrosion Dissolution of iron in lithium Tritium Release in the breeder Lithium LiPb Diffusion through: Ferritic Steel 300ºC 500ºC Vanadium 500ºC 700ºC ~30 s ~100 s 1 to 2 s ~4 s 1 s 20 s 4 s 300 s 40 days 30 days 30 min 2230 days 62 days 47 min 41 min Table XXI.* Characteristic Time Constants in Liquid-Metal Breeder Blankets * From Fusion Technology, Vol. 29, pp 1-57, January 1996

24. List of Journal Papers & Reports(examples only) • Abdou, M. “ITER Test Program: Key Technical Aspects,” Fusion Technology 19(May 1991) 1439+ • Gierszewski, P., Abdou, M., Bell, et al. “Engineering Scaling and Quantification of the Test Requirements for Fusion Nuclear Technology,” Fusion Technology 8 (July 1985) 1100 • Abdou, M., et al. “A Study of the Issues and Experiments for Fusion Nuclear Technology,” Fusion Technology 8 (1985) 2595 • Abdou, M., et al. “Technical Issues and Requirements of Experiments and Facilities for Fusion Nuclear Technology,” Nuclear Fusion 27 (1987) 4, 619 • Abdou, M., Berk, S., Ying, A., et al. “Results of an International Study on a High-Volume Plasma-Based Neutron Source for Fusion Blanket Development,” Fusion Technology 29 (1996) 1-57 • “Test Program Summary,” ITER-IL-NE-3-0-5, ITER Document, February 1990 • “Test Program Summary,” ITER-IL-NE-3-9-4, ITER Document, July 1989 • There are numerous topical reports from INTOR, ITER-CDA and ITER-EDA. Contact M. Abdou for copies of the US reports (1980-1997)

25. Current physics and technology concepts lead to a “narrow window” for attaining Tritium self-sufficiency Fusion power 1.5GW Reserve time 2 days Waste removal efficiency 0.9 (See paper for details) td = doubling time Required TBR td=1 yr Max achievable TBR ≤ 1.15 td=5 yr td=10 yr “Window” for Tritium self sufficiency Fractional burn-up [%]

26. 10 mm 22 mm 49 mm ITER First Wall Panel Cross Section Serious Engineering Design of a breeding blanket (in particular real structural engineering design is lacking): Potential for tritium self sufficiency is uncertain. (Is DT fusion feasible?) −The only serious engineering design in ITER (for non-breeding blanket) shows a need for a thick first wall??!). Plasma Coolant channel • Thick first walls (>1cm) seriously threaten the ability to attain tritium self sufficiency, hence the feasibility of DT fusion • Real Engineering Design of breeding blankets is needed as part of evaluating blanket options Units: mm EU-First wall design

27. Tritium Consumption in ITER • Here is from a summary of the final design report. Link is:http://fusion.gat.com/iter/iter-ga/images/pdfs/cost_estimates.pdf • 9.4.3 Fuel CostsThe ITER plant must be operated, taking into account the available tritium externally supplied. The net tritium consumption is 0.4 g/plasma pulse at 500 MW burn with a flat top of 400 s • “The total tritium received on site during the first 10 years of operation, amounts to 6.7 kg.” • “whereas the total consumption of tritium during the plant life time may be up to 16 kg to provide a fluence of 0.3 MWa/m2 in average on the first wall” • “This corresponds, due to tritium decay, to a purchase of about 17.5 kg of tritium. This will be well within, for instance, the available Canadian reserves.”

28. Separate Devices for Burning Plasma and FNT Development, i.e. ITER + CTF are more Cost Effective and Faster than a Single Combined Device(to change ITER design to satisfy FNT testing requirements is very expensive and not practical. To do it in “DEMO” is impossible) FACTS - World Maximum Tritium Supply (mainly CANDU) available for Fusion is 27 kg - Tritium decays at 5.47% per year - Tritium cost now is $30M / kg. More tritium will cost $200M / kg. Conclusion: - There is no external tritium supply to do FNT testing development in a large power DT fusion device. FNT development must be in a small fusion power device.

29. Projections for World Tritium Supply Available to Fusion for Various Scenarios (Willms, et al.) See calculation assumptions in Table S/Z • World Tritium Supply would be Exhausted by 2025 if ITER were to run at 1000 MW fusion power with 10% availability • There is no external tritium supply to do FNT testing development in a large power DT fusion device. FNT development must be in a small fusion power device. • We need 5-10 kg of tritium as “start-up” inventory for DEMO (can be provided from CTF operating with TBR > 1 at later stage of operation) • Blanket/PFC must be developed in the near termprior to DEMO (and we cannot wait very long for blanket/PFC development even if we want to delay DEMO).

30. Table S/Z (data used in Fig. for Tritium Supply and Consumption Calculations) Tritium Supply Calculation Assumptions: • Ontario Power Generation (OPG) has seven of twenty CANDU reactors idled • Reactors licensed for 40 years • 15 kg tritium in 1999 • 1999 tritium recovery rate was 2.1 kg/yr • Tritium recovery rate will decrease to 1.7 kg/yr in 2005 and remain at this level until 2025 • After 2025 reactors will reach their end-of-life and the tritium recovery rate will decrease rapidly • OPG sells 0.1 kg/yr to non-ITER/VNS users • Tritium decays at 5.47 % / yr It is assumed that the following will NOT happen: • Extending CANDU lifetime to 60 years • Restarting idle CANDU’s • Processing moderator from non-OPG CANDU’s (Quebec, New Brunswick) • Building more CANDU’s • Irradiating Li targets in commercial reactors (including CANDU’s) • Obtaining tritium from weapons programs of “nuclear superpowers” • Premature shutdown of CANDU reactors

31. Table S/Z (cont’d) (data used in Fig. for Tritium Supply and Consumption Calculations cont’d) ITER-FEAT Assumptions: • Construction starts in 2004 and lasts 10 years • There are four years of non-tritium operation • This is followed by 16 years of tritium operation. The first five years use tritium at a linearly increasing rate reaching 1.08 kg T used per year in the fifth year. Tritium usage remains at this level for the remainder of tritium operations. • There is no tritium breeding (TBR=0) • There is no additional tritium needed to fill materials and systems CTF Assumptions: • Begins burning tritium in 2017 • 5 yr, 100 MW, 20% availability, TBR 0.6 • 5 yr, 120 MW, 30% availability, TBR 1.15 • 10 yr, 150 MW, 30% availability, TBR 1.3

32. ITER Impact on Canadian/Korean Candu Tritium Inventory (March 2007) (from Scott Willms, LANL) • Following the methodology developed for the Snowmass and 35-year fusion development plan exercises, the impact of ITER (the seven party agreement signed 11/07) on tritium available from both Canada and Korea was analyzed. • The assumptions were: • Use the same assumption for Canadian tritium as was used for the 35-yr development plan • In addition to the Canadian tritium, Korean tritium is available for fusion (about a 25% additional amount of tritium) • ITER has a 2 kg tritium working inventory which is built up over two years beginning in 2018 • ITER first plasma is 2016 with 3 yr HH, 1 yr DD following by tritium operations • ITER tritium operations are 6 yr followed by 1 year maintenance (no tritium burned) followed by 10 year tritium • The first 10 year campaign includes three yr HH, 1 yr DD and then builds to 1.08 kg tritium burned per year over a five year period, then remains flat to the end of the first 10 years (modification of scenario communicated by Janeschitz at Snowmass 2002) • The second 10 years burns 1.43 kg tritium per year for each of the 10 years. This builds the wall irradiation to 0.3 MW-yr/m2 (neutrons) average over a 680 m2 wall • Between the two 10-yr campaigns there is a one year maintenance phase which presumably includes a first wall replacement. The first 10 year would not irradiate the first wall to 0.3 MW-yr/m2. The new first wall installed at the beginning of the second 10-yr increases from 0 to 0.3 MW-yr/m2 linearly over the second 10 yr. • At the end of ITER a total of 1 kg of tritium is lost to waste and 1 kg of tritium is returned to Canada/Korea • The only demand on the Canadian/Korean tritium is 0.1 kg/yr for sales and ITER. That is, there is no accounting for other demands on this tritium such as CTF or Demo. • There is no tritium breeding in ITER • Note: There has been no signaling from Korea that they will supply tritium to ITER. They are only recovering tritium to get it out of their heavy water. Canada assisted Korea with the installation of their tritium recovery system, and it is not known what contractual agreements they may have. Korean tritium sales, if they took place, would be in competition with Canada. • The results on the following figure show: • Upper Curve: The Canadian/Korean tritium inventory without fusion. This assumes the only demand on this tritium is decay and 0.1 kg/yr sales. • Middle Curve: The Canadian/Korean tritium inventory with the above + ITER • Lower Curve: The yearly ITER transactions with the Canadian/Korean tritium due to ITER tritium inventory build up (down) + decay + burn • Observations: • With these assumptions there is enough tritium for ITER, and about 5 kg of tritium would remain at the end of ITER • The tritium supply would not accommodate any significant extension of ITER, loss of tritium or significant fusion experiment requiring tritium • There is a marginal amount of tritium remaining to startup one Demo, and tritium breeding on that one machine would have to work “out of the box”

33. [0.5-1.5] mm/s [18-54] mm/s Neutron Multiplier Be, Be12Ti (<2mm) Tritium Breeder Li2TiO3 (<2mm) PbLi flow scheme First Wall (RAFS, F82H) Surface Heat Flux Neutron Wall Load Blanket systems are complex and have many integrated functions, materials, and interfaces

34. Fusion environment is unique and complex:multi-component fields with gradients • Particle Flux(energy and density, gradients) • Magnetic Field (3-component with gradients) • Steady Field • Time-Varying Field • Mechanical Forces • Normal/Off-Normal • Thermal/Chemical/Mechanical/ Electrical/Magnetic Interactions • Neutrons (fluence, spectrum, temporal and spatial gradients) • Radiation Effects (at relevant temperatures, stresses, loading conditions) • Bulk Heating • Tritium Production • Activation • Heat Sources (magnitude, gradient) • Bulk (from neutrons and gammas) • Surface • Synergistic Effects • Combined environmental loading conditions • Interactions among physical elements of components Multi-function blanket in multi-component field environmentleads to: • Multi-Physics, Multi-Scale PhenomenaRich Science to Study - Synergistic effectsthatcannotbe anticipated from simulations & separate effects tests. A true fusion environment is ESSENTIAL to activate mechanisms that cause prototypical coupled phenomena and integrated behavior

35. Fusion “Break-in” & Scientific Exploration Stage I 0.5 MW/m2, burn > 200 s 0.1 – 0.3 MW-y/m2, Sub-Modules/Modules • Initial exploration of coupled phenomena in a fusion environment • Uncover unexpected synergistic effects, Calibrate non-fusion tests • Impact of rapid property changes in early life • Integrated environmental data for model improvement and simulation benchmarking • Develop experimental techniques and test instrumentation • Screen and narrow the many material combinations, design choices, and blanket design concepts See Neil Morley’s presentation on Fusion Blanket Phenomena and Timescales

36. Engineering Feasibility & Performance Verification Stage II 1 - 3 MW-y/m2, 1-2 MW/m2, steady state or long pulse, COT ~ 1-2 weeks Modules • Uncover unexpected synergistic effects coupled to radiation interactions in materials, interfaces, and configurations • Verify performance beyond beginning of life and until changes in properties become small (changes are substantial up to ~ 1-2 MW · y/m2) • Initial data on failure modes & effects • Establish engineering feasibility of blankets (satisfy basic functions & performance, up to 10 to 20 % of lifetime) • Select 2 or 3 concepts for further development

37. Component Engineering Development & Reliability Growth Stage III > 4 - 6 MW-y/m2, 1-2 MW/m2, steady state or long burn, COT ~ 1-2 weeks Modules/Sectors • Identify lifetime limiting failure modes and effects based on full environment coupled interactions • Failure rate data: Develop a data base sufficient to predict mean-time-between-failure with confidence • Iterative design / test / fail / analyze / improve programs aimed at reliability growth and safety • Obtain data to predict mean-time-to-replace (MTTR) for both planned outage and random failure • Develop a database to predict overall availability of FNT components in DEMO

38. Examples of possible Failure Modes in Blanket/First Wall (for solid and liquid breeder blanket concepts) • Cracking around a discontinuity/weld • Crack on shutdown (with cooling) • Solid breeder loses functional capability due to extensive cracking • Cracks in electrical insulators (for liquid metal blankets) • Cracks, thermal shock, vaporization, and melting during disruptions • First wall/breeder structure swelling and creep leading to excessive deformation or first wall/coolant tube failure • Environmentally assisted cracking • Excessive tritium permeation to worker or public areas • Cracks in electrical connections between modules Our concern is that failure rates may be much higher in fusion blankets because they appear to be much more complex than steam generators and the core of fission reactors because of the following points: • Larger numbers of subcomponents and interactions (tubes, welds, breeder, multiplier, coolant, structure, insulators, tritium recovery, etc.). • More damaging, higher energy neutrons. • Other environmental conditions: magnetic field, vacuum, tritium, etc. (for example, a leak from the first wall or blanket module walls into the vacuum system results in failure, while in steam generators and fission reactors, continued operation with leaks is often possible). • Reactor components must penetrate each other; many penetrations have to be provided through the blanket for plasma heating, fueling, exhaust, etc. • Ability to have redundancy inside the blanket / first wall system is practically impossible.

39. Pillars of a Fusion Energy System • Confined and Controlled Burning Plasma (feasibility) • Tritium Fuel Self-Sufficiency (feasibility) • Efficient Heat Extraction and Conversion (attractiveness) • Safe and Environmentally Advantageous (feasibility/attractiveness) • Reliable System Operation (attractiveness) The Blanket is the KEY component and is on the critical path to DEMO Yet, No fusion blanket has ever been built or tested!

40. ( 1 / failure rate ) + 1 / failure rate replacemen t time Reliability/Maintainability/Availability is one of the remaining “Grand Challenges” to Fusion Energy Development. FNT R&D is necessary to meet this Grand Challenge. Need High Power Density/Physics-Technology Partnership - High-Performance Plasma Need Low - - Chamber Technology Capabilities Failure Rate × + + replacement cost C i O & M = COE × × × h P Availability M fusion th Energy Need High Temp. Multiplication Energy Extraction Need High Availability / Simpler Technological and Material Constraints · Need Low Failure Rate: - Innovative Chamber Technology · Need Short Maintenance Time: - Simple Configuration Confinement - Easier to Maintain Chamber Technology

41. Major Activities and Approximate Timeline* for Fusion Nuclear Technology Development H-H • R&D Activities are critical to support effective FNT/Blanket testing in ITER and FNF/CTF • ITER TBM Provides Timely Information to FNF/CTF Arrows indicate major points of FNT information flow through ITER TBM * Need to adjust for new ITER Schedule delay of 2-3 years, similarly for FNF

42. Approximate Costs of Blanket Testingin the Fusion “Break-In” Stage

43. TBM Testing in ITER Reduces Cost and Risk for FNT Development and Shortens the Time to DEMO • ITER already has been designed with capabilities, worth billions of dollars, for testing TBMs, both in hardware and the fusion DT environment capabilities it offers. • ITER operation costs are already paid for, and shared internationally, independent of TBM. • The only cost for TBM is the cost of the TBM experiment (test article+PIE and associated ancillary equipment), which is required for testing in any fusion environment • Exactly the same R&D and qualification testing for ITER TBM will be needed for CTF.But in ITER costs can be shared with international partners. • TBM in ITER providesfusion break-in tests and initial concept screening • Saves at least 2-3 years in CTF operation. This is a huge cost savings when given a CTF operating cost of ~$200 million per year. • Saves on the cost of blanket concept screening by paying only partial cost for two concepts, while getting access to results of many concepts of international parties • ITER TBM will shorten the operating time of CTF, and hence the time to DEMO. • Saving a few years on fusion “break-in” stage; allowing CTF to proceed directly to engineering development and reliability growth • Results will allow better design, construction and operation of test modules for CTF. Thereby, shortening the time required to complete FNT testing in CTF. • ITER is “real” and “unique.” It will provide the first prototypic fusion environment. It is likely to be the only D-T fusion facility available during its first 10 year operation. Missing such a unique opportunity increases the risk of delaying the DEMO schedule.

44. TBM Testing in ITER Reduces Cost and Risk for FNT Development and Shortens the Time to DEMO (cont’d) • ITER TBM, plus additional parallel R&D, is important in providing a solution to the serious tritium supply issue. (Because of the large tritium consumption in ITER, any other fusion device, e.g. CTF, with fusion power > 100 MW and availability of~ 25% will have to breed its own tritium.) • ITER TBM will enable CTF to construct near full breeding blankets in an early stage • ITER TBM will allow better designs of DEMO test modules in CTF • ITER TBM will help CTF achieve its required availability sooner by improving early-life reliability • Experience in safety and licensing of ITER TBM will be essential to the licensing of CTF

45. TBM Testing in ITER (Phase I), combined with CTF, is the most effective development path for FNT • FNT/Blanket development is critical to fusion • A strong base FNT R&D program, together with fusion environment testing is essential • ITER is a unique, unparalleled and “real” opportunity to begin stage I fusion break-in and scientific exploration • ITER will provide the first opportunity (and likely the only one for many years) to explore the fusion environment • Low fusion power CTF is required for stage II engineering feasibility, and stage III reliability growth phases of FNT development • Even if CTF exists parallel to ITER, you still do TBM in addition to CTF • If we do CTF and invest billions to test and develop FNT, this means we are serious. The cost of experiments in ITER is very small and cuts years and huge costs from the required CTF operation • TBM tests in ITER will have prototypical Interactions between the FW/Blanket and Plasma, thus complementing tests in CTF (if CTF plasma and environment are not exactly prototypical, e.g. highly driven with different sensitivity to field ripple, low outboard field with different gradients) • Testing in any fusion environment will require same R&D, qualification, mockup testing, testing systems, licensing as for ITER TBM, none of this effort for ITER TBM is wasted

46. The US can benefit greatly from timely international collaboration with ITER partners • US ingenuity, innovation, and leadership on Fusion Nuclear Technology have strongly influenced the world program over the past 35 years • Many parties have been continuously investing R&D resources in concepts the US invented and which are still of US interest • Other ITER parties are already committing significant resources to their TBM programs • But these parties won’t share their critical preparatory R&D, testing facilities, and TBM experiment results, unless reciprocated • All ITER parties have a strong interest to collaborate and work jointly with the US (giving access information on a larger variety of blanket concepts) • But are concerned about the delay of an official US position and commitment to Test Blanket experiments in ITER An early signal of US commitment and intention of continued leadership will enable negotiating international agreements that best serve US strategic interests