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Presented at FNST Meeting, UCLA August 12-14, 2008

FNST Issues, Development, and Role of Next Step Fusion Nuclear Facility FNF (VNS/CTF/FDF, etc.) and ITER TBM. Presented at FNST Meeting, UCLA August 12-14, 2008. Mohamed Abdou. FNST Issues, Development, and Role of Next Step Fusion Nuclear Facility FNF (VNS/CTF/FDF, etc.) and ITER TBM. Outline

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Presented at FNST Meeting, UCLA August 12-14, 2008

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

  2. FNST Issues, Development, and Role ofNext Step Fusion Nuclear Facility FNF(VNS/CTF/FDF, etc.) and ITER TBM Outline • What is Fusion Nuclear Technology? • Brief Statement of Technical Issues and Role of Non-Fusion and Fusion Testing Facilities • Framework for FNT Development and Requirements • Stages • Parameters • Top Level Issues for FNT Development Facilities • What is FNF (CTF/VNS), Why needed, main features required • Tritium Consumption and Supply and implications • Reliability / Maintainability / Availability (and Reliability Growth Strategy) • Complementary Roles of ITER TBM and FNF • Time, cost, schedule • International collaboration • Selected US Concepts and input to FNF design and testing strategy

  3. Fusion Nuclear Technology (FNT) Fusion Power & Fuel Cycle Technology FNT Components from the edge of the Plasma to TF Coils(Reactor “Core”) 1. Blanket Components (includ. FW) 2. Plasma Interactive and High Heat Flux Components a. divertor, limiter b. rf antennas, launchers, wave guides, etc. 3. Vacuum Vessel & Shield Components Other Systems / Components affected by the Nuclear Environment 4. Tritium Processing Systems 5. Instrumentation and Control Systems 6. Remote Maintenance Components 7. Heat Transport and Power Conversion Systems

  4. Notes on FNT/FNST: • The fusion nuclear field involves many scientific issues and technical disciplines as well as engineering and component development- hence it is often called Fusion Nuclear Science and Technology (FNST) • The first wall is an integral part of the blanket. The term “Blanket” implicitly includes the first wall. • The Vacuum Vessel is outside the Blanket/Shield in a low-radiation field. • The Key Issues are for Blanket / PFC: Highest heat and radiation fluxes • The location of the Blanket inside the vacuum vessel is necessary but has major consequences:a- many failures (e.g. coolant leak) require immediate shutdown b- repair/replacement take long time

  5. R&D Tasks to be Accomplished Prior to Demo 1) Plasma - Current Drive/Steady State - Confinement/Burn - Edge Control - Disruption Control 2) Plasma Support Systems - Diagnostics - Superconducting Magnets - Fueling - Heating 3) Fusion Nuclear Technology Components and Materials [Blanket (including First Wall), Divertors, rf Launchers] - Materials combination selection and configuration optimization - Performance verification and concept validation - Tritium self sufficiency in practical system - Failure modes and effects - Remote maintenance - Reliability growth - Component lifetime 4) Systems Integration Where Will These Tasks be Done?! • Burning Plasma Facility (ITER) and other plasma devices will address 1, 2, & much of 4 • How and Where Will Fusion Nuclear Technology (FNT) be developed?(ITER alone?, another device?, both?)

  6. Numerous technical studies were performed over the past 30 years in the US and worldwide to study issues, experiments, facilities, and pathways for FNST development • This is probably the most studied subject in fusion development • This is an area where the US has played a major leadership role in the world program and provided major contributions such as engineering scaling laws for testing, VNS/CTF/FNF concept, and blanket designs • These studies involved many organizations (Universities, National Labs, Industry, and Utilities) and many scientists, engineers, and plasma physicists. Industry participation was particularly very strong from Fission and Aerospace and they provided substantial contributions. • Examples of Major Studies on FNST/Blanket • Blanket Comparison and Selection Study (1982-84, led by ANL) • FINESSE Study (1983-86, led by UCLA) • IEA Study on VNS/CTF (1994-96 US, EU, J, RF) • ITER TBM (1987-present), US ITER TBM Planning and Costing(2003-2007) • Other studies that provided important input: DEMO Study (led by ANL 1981-1983) and many Power Plant Studies (UWMAKs, STARFIRE, ARIES, others in EU,J,RF) • Many Planning activities discussed FNT and provided input (TPA, FESAC, etc) These studies resulted in important conclusions and illuminated the pathways for FNST and fusion development

  7. Summary of Critical R&D Issues for Fusion Nuclear Science and Technology (FNST) • D-T fuel cycle tritiumself-sufficiency in a practical system depends on many physics and engineering parameters / details: e.g. fractional burn-up in plasma, tritium inventories, FW thickness, penetrations, passive coils, doubling time 2. Tritium extraction and inventory in the solid/liquid breeders under actual operating conditions 3.Thermomechanicalloadings and (MHD) Thermofluid response of blanket and PFC components under normal and off-normal operation 4. Materials interactions and compatibility 5. Identification and characterization of failure modes, effects, and rates in blankets and PFC’s • Engineering feasibility and reliability of electric (MHD) insulators and tritium permeation barriers under thermal / mechanical / electrical / magnetic / nuclear loadings with high temperature and stress gradients 7. Tritium permeation, control and inventory in blanket and PFC 8. Remote maintenance with acceptable machine shutdown time. 9. Lifetime of blanket, PFC, and other FNT components

  8. International studies on FNST have concluded: • Testing in non-fusion facilities is necessary prior to testing in fusion facilities. Non-fusion facilities can and should be used to narrow material and design concept options and to reduce the costs and risks of the more costly and complex tests in the fusion environment. Extensive R&D programs on non-fusion facilities should start now. ~10-15 years of R&D, design, analysis, and mockup testing are required to qualify blanket test modules for testing in any nuclear fusion facility - However, non-fusion facilities cannot fully resolve any of the critical issues for blankets There are critical issues for which no significant information can be obtained from testing in non-fusion facilities (An example is identification and characterization of failure modes, effects and rates). Even some key separate effects in the blanket can not be produced in non-fusion facilities (e.g. volumetric heating with blanket-typical gradients) • Extensive Testing in Fusion Facilities is necessary prior to DEMO. Even the “Feasibility” of Blanket Concepts can NOT be established prior to testing in fusion facilities

  9. Types of experiments, facilities and modeling for FNT Theory/Modeling Design Codes Basic Separate Effects Multiple Interactions Partially Integrated Integrated Component Design Verification & Reliability Data • Fusion Env. Exploration Property Measurement Phenomena Exploration • Concept Screening • Performance Verification Non-Fusion Facilities (non neutron test stands, fission reactors and accelerator-based neutron sources) Testing in Fusion Facilities • Non fusion facilities (e.g. non-neutron test stands, fission reactors and neutron sources) are essential and have important roles • Testing in Fusion Facilities is NECESSARY for multiple interactions, partially integrated, integrated, and component tests

  10. Stages of FNST Testing in Fusion Facilities D E M O Component Engineering Development & Reliability Growth Engineering Feasibility & Performance Verification Fusion “Break-in” & Scientific Exploration Stage I Stage II Stage III 1 - 3 MW-y/m2 > 4 - 6 MW-y/m2 0.1 – 0.3 MW-y/m2 1-2 MW/m2 steady state or long pulse COT ~ 1-2 weeks 1-2 MW/m2 steady state or long burn COT ~ 1-2 weeks 0.5 MW/m2, burn > 200 s Sub-Modules/Modules Modules Modules/Sectors • 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 • 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 • 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

  11. FNST Requirements for Major Parameters for Testing in Fusion Facilities with Emphasis on Testing Needs to Construct DEMO Blanket • These requirements have been extensively studied over the past 20 years, and they have been agreed to internationally (FINESSE, ITER Testing Blanket Working Group, IEA-VNS, etc.) - Many Journal Papers published (>35), e.g. IEA-VNS Study Paper (Fusion Technology, Vol. 29, Jan 1996) a - Prototypical surface heat flux (exposure of first wall to plasma is critical) b - For stages II & III. If steady state is unattainable, the alternative is long plasma burn with plasma duty cycle >80% c - Initial fusion break-in has less demanding requirements than stages II & III d - Note that the fluence is not an accumulated fluence on “the same test article”; rather it is derived from testing “time” on “successive” test articles dictated by “reliability growth” requirements

  12. Critical Factors in Deciding where to do Blanket / FNT Fusion Testing and that have Major Impact on FNT (and Fusion) Development Pathway • Tritium Consumption / Supply Issue • Reliability / Maintainability / Availability Issue • Cost, Risk, Schedule The idea of a Fusion Nuclear Facility, FNF (also called VNS, CTF, etc) dedicated to FNST testing was born out of the analyses of these critical factors

  13. What is FNF (CTF/VNS)? • The idea of FNF (also called VNS, CTF) is to build a small size, low fusion power DT plasma-based device in which Fusion Nuclear Science and Technology (FNST) experiments can be performed in the relevant fusion environment: 1- at the smallest possible scale, cost, and risk, and 2- with practical strategy for solving the tritium consumption and supply issues for FNST development. • In MFE: small-size, low fusion power can be obtained in a low-Q (driven) plasma device. • Equivalent in IFE: reduced target yield (and smaller chamber radius?) • This is a faster, much less expensive approach than testing in a large, ignited/high Q plasma device for which tritium consumption, and cost of operating to high fluence are very high (unaffordable!, not practical).

  14. FNF (CTF/VNS) MISSION The mission of FNF is to test, develop, and qualify Fusion Nuclear Components (fusion power and fuel cycle technologies) in prototypical fusion power conditions. The FNF facility will provide the necessary integrated testing environment of high neutron and surface fluxes, steady state plasma (or long pulse with short dwell time), electromagnetic fields, large test area and volume, and high “cumulative" neutron fluence. The testing program on FNF and the FNF device operation will demonstrate the engineering feasibility, provide data on reliability / maintainability / availability, and enable a “reliability growth” development program sufficient to design, construct, and operate blankets, plasma facing and other FNST components for DEMO. FNF will solve the serious tritium supply problem for fusion development by a- not consuming large amounts of tritium, b- breeding much of its own tritium, c- accumulating excess tritium (in later years) sufficient to provide the tritium inventory required for startup of DEMO, and d- developing the blanket technology necessary to ensure DEMO tritium self sufficiency

  15. The issue of external tritium supply is serious and has major implications on FNST (and Fusion) Development Pathway A Successful ITER will exhaust most of the world supply of tritium, but 5-10 kg will be needed to start one DEMO (one DEMO? Other countries will compete for tritium!) Any future long pulse burning plasma device will need tritium breeding technology The availability and cost of external tritium supply is a serious issue for FNST development FNST engineering development and reliability growth stages must be done in a small fusion power device to minimize tritium consumption (only stage I fusion break-in can be done in ITER) 30 CANDU Supply w/o Fusion 25 20 Projected Ontario (OPG) Tritium Inventory (kg) 15 1000 MW Fusion 10% Avail, TBR 0.0 10 ITER-FEAT (2004 start) 5 0 1995 2000 2010 2015 2020 2025 2030 2035 2040 2045 2005 Year Tritium Consumption in Fusion is HUGE! Unprecedented! 55.6 kg per 1000 MW fusion power per year Production & Cost: CANDU Reactors:27 kgfrom over 40 years,$30M/kg (current) Fission reactors:2–3 kg/year $84M-$130M/kg(per DOE Inspector General*) Tritium decays at 5.47% per year *www.ig.energy.gov/documents/CalendarYear2003/ig-0632.pdf See Table S/Z Tritium Breeding Blankets must be developed in the near term to solve the serious issue of external tritium supplyWe cannot wait very long for blanket development

  16. Updated projections of Canadian + Korean tritium supply and consumption using ITER current schedule Canadian + Korean Inventory without supply to fusion Canadian + Korean Inventory with ITER (From Scott Willms [March 2007]). Notes & assumptions given on a separate slide.

  17. Tritium Breeding Requirements for FNF • Available External Supply after ITER use is very limited (and very expensive) • FNF has to breed tritium to: a- supply most or all of its consumption b- accumulate excess tritium (in later years) sufficient to provide the tritium inventory required for startup of DEMO • The required TBR in FNF depends on: • FNF fusion power • start date of FNF • start date of ITER and whether ITER extended phase (second 10 yrs) will be approved • Assuming that the entire tritium inventory from Canada and Korea not used by ITER is available for use in FNF, the required TBR in FNF is: • to supply its consumption: TBR < 1 (and increases with FNF fusion power) • to supply consumption plus DEMO startup inventory: TBR > 1 (and is higher for smaller power for DEMO inventory >> 5Kg) • A scenario for FNF in which TBR is low initially (when availability is low) and higher in later years (when availability is ~30%) is worth considering • See M. Sawan Presentation for detailed results

  18. Reliability / Availability / Maintainability (RAM) • RAM, particularly for nuclear components, is one of the most challenging issues for DEMO and Power Plants. • A primary goal of FNF is to solve the RAM issue by providing for “reliability growth” testing and maintenance experience • But achieving a reasonable Availability in the FNF device is by itself a challenge • RAM has a MAJOR impact on : • Defining the FNST Testing Requirements to achieve given goals for DEMO. This directly defines FNF major parameters e.g. Fluence, number of test modules , test area, availability, and testing strategy in FNF • Design and Development of FNF to achieve its availability goals • RAM is a complex topic for which the fusion field does not have an R&D program or dedicated experts. A number of fusion engineers tried over the past 3 decades to study it and derive important guidelines for FNST and Fusion development

  19. Device Availability is reduced by two types of outages Scheduled Outage: (This you design for) Planned outage (e.g. scheduled maintenance of components, scheduled replacement of components, e.g. first wall at the end of life, etc.). This tends to be manageable because you can plan scheduled maintenance / replacement operations to occur simultaneously in the same time period. Unscheduled Outage:(Can kill your DEMO and your future) Failures do occur in any engineering system. Since they are random they are much worse than scheduled outages and tend to have the most serious impact on availability. This is why “reliability/availability analysis,” reliability testing, and “reliability growth” programs are key elements in any engineering development.

  20. Plasma Duty Factor = Some RAM terminology Device Availability or Device Duty Factor= AS x AU AS = Availability Due to Scheduled Outage Au = Availability Due to Unscheduled Events Au represents a component = (Outage Risk) = (failure rate) • (mean time to repair) = MTBF = mean time between failures = 1/failure rate MTTR = mean time to repair (Plasma duty factor = 1 for steady state operation) Fluence (integrated neutron wall load) = Neutron wall load x Calendar years x (Device Duty Factor x Plasma Duty Factor)

  21. Availability (Due to Unscheduled Events) Availability: = represents a component (Outage Risk) = (failure rate) • (mean time to repair) = MTBF = mean time between failures = 1/failure rate MTTR = mean time to repair • A Practical Engineering System must have: 1. Long MTBF: have sufficient reliability - MTBF depends on reliability of components. One can estimate what MTBF is NEEDED from “availability allocation models” for a given availability goal and for given (assumed) MTTR. But predicting what MTBF is ACHIEVEABLE requires real data from integrated tests in the fusion environment. 2. Short MTTR: be able to recover from failure in a short time - MTTR depends on the complexity and characteristics of the system (e.g. confinement configurations, component blanket design and configuration, nature of failure). Can estimate, but need to demonstrate MTTR in fusion test facility.

  22. DEMO Availability of 50% Requires Blanket Availability ~88% (Table based on information from J. Sheffield’s memo to the Dev Path Panel) Assuming 0.2 as a fraction of year scheduled for regular maintenance. Demo Availability = 0.8* [1/(1+0.624)] = 0.49 (Blanket Availability must be .88 and blanket MTBF must be > 11 years!)

  23. Current confinement concepts have long blanket MTTR > 1 month because of a- complex configuration, and b- the blanket is INSIDE the vacuum vessel. (compared to replacement time of ~ 2 days of fuel in fission reactors) This leads to reliability requirements on the Blanket/FW that are most challenging. These must be seriously addressed as an integral part of the R&D pathway to DEMO. It is one of the key DRIVERS for FNF/CTF/VNS. A = Expected with extensive R&D (based on mature technology and no fusion-specific failure modes) C = Potential improvements with aggressive R&D

  24. 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

  25. MTTR = 1 month 1 failure during the test 80 blanket modules in blanket system Experience factor =0.8 Neutron wall load = 2 MW/m2 Obtainable Blanket System Availability with 50%Confidence for Different Testing Fluences and Test Areas Test area per test article =0.5 m2 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. Reliability Growth Testing Requires: 1- “Cumulative” testing fluence of > 6 MW∙y/m2 2- Number of test modules per concept ~ 10-20

  26. How Many Modules/SubmodulesNeed to Be Tested For Any Given One Blanket Concept? Never assume one module. 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 & operation limits) These requirements are based on “functional” and engineering scaling requirements. There are other more demanding requirements for “Reliability Growth” as discussed earlier (10-20 modules per concept)

  27. ComplementaryRoles forITER TBM and FNF lead to optimal FNST pathway D E M O Role of FNF (CTF/VNS) Role of ITER TBM Component Engineering Development & Reliability Growth Engineering Feasibility & Performance Verification Fusion “Break-in” & Scientific Exploration Stage III Stage I Stage II 1 - 3 MW-y/m2 > 4 - 6 MW-y/m2 0.1 – 0.3 MW-y/m2 1-2 MW/m2, steady state or long pulse COT ~ 1-2 weeks 1-2 MW/m2, steady state or long burn COT ~ 1-2 weeks 0.5 MW/m2, burn > 200 s Sub-Modules/Modules Modules/Sectors 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 • 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 • 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

  28. Analysis of benefits, costs, risks, and schedule shows thatTBM testing in ITER, combined with FNF, clearly providesthe best approach for FNT development for DEMO • Best Approach to FNT Development: • Role of ITER TBM:Perform Stage I • Fusion Break-in and scientific exploration and initial blanket concept screening • Role of FNF: Perform Stages II and III • Stage II: Engineering Feasibility and Performance Verification • Stage III:Component Engineering Development and Reliability Growth

  29. TBM Tests in any fusion facility need a whole TBM System (TBM + “Ancillary Equipment”) For example: PbLi loop with heat exchanger, tritium extraction system, He-coolant circuits with pumps and heat exchangers, etc. For FNF / CTF such Ancillary Equipment will also be needed for each module of base breeding blanket and for each test module He pipes to TCWS PbLi loop TBM Port Frame VV Port Extension TBM Bio-shield Transporter

  30. US Selected Concepts and Strategy • In 2003 an extensive effort by the US community was devoted to selection of reference US Blanket Concept(s). Two concepts, the Dual-Coolant Lead-Lithium (DCLL) and the Helium-Cooled Ceramic Breeder (HCCB) have been selected. Key Reasons for Selection of the TWO Concepts: • DCLL provides pathway toward high temperature, high performance blankets using ferritic steel structure • HCCB is modest performance, but less feasibility issues and is of interest to all world programs • The US plays a lead role for DCLL and supporting role for HCCB in the world program • Two different classes of blanket concepts that have substantially different feasibility issues to avoid the situation where a fatal flaw may eliminate the only concept.

  31. Highlights of the two US Reference Blanket concepts Poloidal flow PbLi channel Purge gas pipe He-cooled RAFS FW SiC FCIs Ceramic breeder pebbles Be Pebbles He-cooled RAFS FW DCCL Module HCCB Module • Helium (~8 MPa) coolant operating (350C-500C) • Low pressure (0.1-0.2 MPa) helium/H2 purge gas to extract tritium The Dual-Coolant PbLi Liquid Breeder Blanket (DCLL) concept with helium-cooled structure and self-cooled PbLi breeding zone with flow channel inserts (FCIs) as MHD and thermal insulator. • “Pathway” to higher outlettemperature/higher thermal efficiency while using ferritic steel. The Helium-Cooled Ceramic Breeder Blanket (HCCB) concept with ferritic steel structure and beryllium neutron multiplier • Likely near term breeding blanket - all parties interested

  32. Blanket Concepts Proposed by 7 Parties for ITER Testing • Proposed 12 designs for TBM’s representing 7 classes of concepts • But there is much common R&D (e.g. for ferritic steel, ceramic breeder, PbLi) among the concepts

  33. Conclusions Conclusions will be given AFTER Discussion

  34. Discussion Topics • Discussion on Base Blanket for FNF: • What are the options for a base breeding blanket (structural materials, coolants, breeding materials, etc.)? • Are there good reasons for using a non-breeding base blanket rather than a breeding base blanket? • Is there a base breeding blanket option for which there will be more data/experience/confidence than those for the primary blanket concepts for the test modules? • Discussion on Divertor Options for FNF: • What are the expected heat and particle loads on FNF divertor, and how do they compare to ITER? • What are the preferred material and coolant options? • What database/experience is required?

  35. Discussion Topics (cont.) • Discussion on Reliability/Maintainability/Availability in FNF: • What availability goals are required for FNF? What are the corresponding MTBF and MTTR for various components and for base blanket? • What are the requirements on periods of continuous operations (test campaigns)? What are the requirements on the plasma duty cycle during these test campaigns? • What is the minimum achievable plasma dwell time? Maximum burn time during a pulse? Maximum plasma duty cycle? • What is needed to realize the above goals for the device availability factor and plasma duty factor? • Discussion on testing strategies on FNF: • What are the preferred blankets options for testing on FNF and what are the implications for R&D? • Comparison of strategies for testing space allocation on FNF: • a) all or most outboard occupied by test modules/test sectors • b) base blanket with test modules in test ports (ITER type) • Number of blanket concepts to be tested in FNF in 2 cases: • a) Assuming ITER TBM is carried out • b) With no US ITER TBM • R&D required to place a test module on FNF (how does it compare to ITER TBM?) • R&D required for base blanket • Discussion on Mapping into Greenwald Gaps for FNST

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