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RENEW THEME IV WORKSHOP

RENEW THEME IV WORKSHOP. Power Extraction Panel Overview Robust operation of blanket/firstwall and divertor systems at temperatures suitable for efficient power conversion.

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RENEW THEME IV WORKSHOP

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  1. RENEW THEME IV WORKSHOP Power Extraction Panel Overview Robust operation of blanket/firstwall and divertor systems at temperatures suitable for efficient power conversion PANEL MEMBERS:Neil Morley, Charlie Baker, Pattrick Calderoni, Richard Nygren, Arthur Rowcliffe, Mohamed Sawan, Ron Stambaugh, Grady Yoder UCLA, March 2-4, 2009

  2. What is in this presentation? Proposed thrusts will be discussed during Power Extraction session Tuesday AM An apology Recap Greenwald report issues and gap statement PeX Panel work on issues and gaps w/ DEMO as goal Research needs, tools and expertise needed Q&A and Discussion ?? 5 minutes after each presentation plus discussion sessions

  3. Greenwald Report on Power Extraction‘What hath gone before’ PeX Panel input “Power extraction is a fundamental challenge for an attractive fusion energy source. The scientific issues encountered in fusion power extraction are substantially different than other energy sources including fission.” “The research in this area to date has been mainly limited to concept exploration and some single-effect experimentation. There is a fundamental need to develop the engineering science of power extraction” The R&D may be more advanced than just single-effect, especially in EU/JA where investment in this area is strong. But the US has not supported a strong program and much remains to be done

  4. What is included in Power Extraction? PeX Panel input Components • Divertor/Baffles • FW/Blanket/Shield • Primary Coolant Loops • Heat exchangers • Power Conversion Cycle

  5. Greenwald Report on Power Extraction PeX Panel input Scientific Challenges and Associated Integration Issues Understanding the thermo-fluid dynamics of power extraction components (divertor, first wall / Blanket) Understanding the generation and transport of tritium and activation products Understanding multi-physics phenomena Understanding life-limiting and failure mechanisms in power extraction components Direct linkage with plasma facing components, plasma operation, tritium fuel cycle, material, and safety issues. Enabling technology for long pulse, burning plasma experiments Ability to Simulate/Predict and Diagnosis/Control power extraction components behavior Understanding of fabrication processes and their effect on power extraction components materials, behavior and design Include linkage with RAMI

  6. Greenwald Report on Power Extraction PeX Panel input Unique Fusion Attributes of Power Extraction Very high surface heat flux and potentially high peaking factors, Complex volumetric heating source …. plasma products (neutrons, particles, radiation) .. nuclear reactions .. Strong impact of EM field (both static and dynamic) on heat transfer, Large temperature and stress gradients …….. multitude of complex physical phenomena, Compatibility with the fuel cycle (tritium production and extraction), Complex geometry, and evolving material properties (e.g., .. radiation effects). Stringent requirements on space, failure tolerance & reliability (from component location inside VV) Compatibility with plasma configuration, operation & control

  7. Greenwald Report on Gaps single overarching gap devoted to Power Extraction PeX Panel input • Noted no specific, detailed PeX Gaps included in the Greebwald Report individual section (note the panel will give its estimation of PeX gaps after reviewing Greenwald) G-12. An engineering science base for the effective removal of heat at high temperatures from first wall and breeding components in the fusion environment. Strategies for removing heat, at elevated temperatures with limited maintenance, from the blankets and first wall must be developed. Efficient and reliable methods for conversion of the heat in the high temperature coolant, including allowances for the unique role associated with tritium management issues, need to be developed and demonstrated on dedicated test stands.

  8. Greenwald Report on Power Extraction Many other gaps give issues that relate to Power Extraction .. G-10. Understanding .. use of low activation solid & liquid mat’ls, joining .. cooling strategies sufficient to design robust FW & div. .. … in a high heat flux, steady-state nuclear environment. G-11. Understanding the elements of the complete fuel cycle particularly tritium breeding and retention in vessel components. G-13. Understanding .. evolving properties of low activation mat’ls .. necessary for structural and first wall components. G-14. .. knowledge base .. sufficient to guarantee safety over the plant life cycle - including licensing and commissioning, normal operation, off-normal events and decommissioning/disposal. G-15. knowledge base for efficient maintainability of in-vessel components to guarantee the availability goals of Demo are achievable.

  9. Greenwald Report on Power Extraction G10a. Understanding and characterization of welds, brazes and other joining techniques under fusion environment. G10b. Strategies for efficient heat removal at high temp. with gas coolant G10c. Liquid-surface first walls (very early level of development) • compatibility of the liquids with structures, MHD effects on moving conductors and contamination of plasma by evaporation or sputtering G11a. Choice of breeding material and the basic thermal-hydraulics G11b. Breeding modules, capable of maintaining structural integrity at high temperatures in the presence of large neutron fluence G13a. basic understanding of the behavior of relevant low-activation materials exposed to simultaneous • fusion neutron irradiation, high heat fluxes, & substantial stresses … and subordinate specifics that relate to Power Extraction

  10. Greenwald Report on Power Extraction … and subordinate specifics that relate to Power Extraction G14a. Comprehensive models … must be developed to support safety analysis and licensing – especially dynamic models G14b. Large scale fusion components must be qualified and experience gained with their remote handling. G14c. Strategies to control and account for total tritium inventory must be developed along with plans for long term waste management and disposal. G15a. In-vessel components have to incorporate designs that, besides meeting all the performance requirements within a high neutron fluence environment, G15b. The material selected for joints or attachment points will have to be carefully chosen, with the expectation that multiple cutting and rewelding operations may take place

  11. So, what has the ReNeWPower Extraction Panel been doing? • Reading and discussing Greenwald report issues and gaps related to Power Extraction and closely coupled areas • Assembling a slightly more expansive list of Power Extraction specific and related issues (we have 10, but more may be needed) • Attempting to provide detail of these Power Extraction issues in terms of: • Key questions • Detailed examples • Status and current/upcoming work (Where we are at…) • Specific gaps to Demo • Research needs (What is needed…) • Organization of research needs into proposed thrusts (just started)

  12. So, what has the ReNeWPower Extraction Panel been doing? • Reading and discussing Greenwald report issues and gaps related to Power Extraction and closely coupled areas • Assembling a slightly more expansive list of Power Extraction specific and related issues (we have 10, but more may be needed) • Attempting to provide detail of these Power Extraction issues in terms of: • Key questions • Detailed examples • Status and current/upcoming work (Where we are at…) • Specific gaps to Demo • Research needs (What is needed…) • Organization of research needs into proposed thrusts (tomorrow)

  13. FINDINGS of the Power Extraction Panel (1) Summary of Power Extraction Gaps • Accurate knowledge of spatial and temporal temperature variations, coolant flow, and transport phenomena at fusion relevant parameters • Requirements and techniques for control of coolant chemistry and impurities • Knowledge about occurrence and impact of synergistic phenomena in Power Extraction components resulting from multi-field, multi-material, or multi-function effects • Knowledge of how to fabricate, maintain, and diagnose complex Power Extraction component experiments, modules and loops with fusion relevant materials • Integration of knowledge base into models capable to predict Power Extraction component behavior beyond parameters of the experimental database and acceptable to design/license components for Demo • Design and R&D on alternatives to mainline concepts for divertor and FW/Blankets (e.g. with different materials or feasibility issues, improved margin or performance)

  14. FINDINGS of the Power Extraction Panel (2) Not possible to decoupling Power Extraction research from other elements of Harnessing Fusion Power Theme • Power extraction is a driver of component temperature • Higher temperature is better for power conversion efficiency or process heat • Temperature in turn influences/drives many phenomena: thermal stress, creep, tritium permeation/recycling from PFCs, corrosion processes, etc. • It is clear that the fuel cycle and power extraction are directly linked • Blankets and supporting systems must perform both functions of power extraction and tritium breeding/extraction. • The FW and divertor can be sites for tritium holdup as well as blanket materials (such as breeders and multipliers) • Materials, Safety, RAMI help set the boundaries of what is possible and what is acceptable for power extraction component designs

  15. FINDINGS of the Power Extraction Panel (3) The requirements of PMI, Magnetic Configuration, Plasma Control and Off-normal events have to be developed in concert with real Power Extraction components, material requirements, and operation temperatures • PFC is really a special case of power extraction -- interfacing power extraction with PWI and particle pumping • Hot wall effects on fuel recycling, trapping • Heat flux control and removal • Configuration and control schemes must be developed with knowledge of power extraction requirements • Location/shielding of control coils • Error field effects from ferritic blanket materials and MHD currents • Integrated solutions needed for fusions most difficult problems • Disruption, VDE, ELM prediction, control, mitigation and survivability • Power extraction is an enabling technology for all long pulse and DT plasma experiments in the future, including ITER

  16. Facilities, Tools, Skills to develop Power Extraction Significant additional human resources and research efforts to: • Emphasize all aspects of Fusion Nuclear Science and Technology PeX, FC, MAT, RAMI, SAFETY, PFC, PWI… • Developing single and multiple effect databases in many areas (not just mainline options) • Training FNST researchers and designers • Incorporate expertise in High performance computing • Incorporation of the knowledge base into models capable to predict Power Extraction component behavior beyond parameters of the experimental database • Validated according to nuclear QA standards • Suitable for integration in overall design codes for Demo • To emphasize development of property measurement techniques and sensors, attachments, data transmission • Temp, Flow, Strain, Pressure, Vibration, Potential, Current, Leak Detection, Flux, Spectrum, Activity, Concentration… • Compatible with a wide range of temperature, materials, plasma, fluence, and electromagnetic conditions

  17. Facilities, Tools, Skills to develop Power Extraction Capability to perform multiple-effect to fully-integrated fusion environment experiments • A set of experimental test facilities that can access multi-field, fusion relevant parameter ranges • Magnetic field / Thermal conditions • Neutron field / Thermal conditions • Plasma / Magnetic / Thermal conditions • Fully integrated fusion environment (pulses from minutes/hours, such as ITER) • Moderate fluence integrated fusion environment (pulses from days/week, such as FNF) • Laboratory to Quasi-industrial capability to fabricate complex mockups/loop components from fusion materials • RAFS, W, …RAFS/ODS • Including integration of functional diagnostics, solid breeders, multipliers, flow channel, inserts, armors,…

  18. This presentation is the current rollup, details continue to be evolved… • Detailed examples and issue descriptions have been partially completed, and are available for viewing and comments • What are we missing: Large issues? Details? We entirely missed the point?? Just too banal??? • NOTE: Thrusts to be discussed during the sessions.

  19. Detailed Issue Description(show only as needed) 2/23 by NBM

  20. Power Extraction Issue 1:Thermofluid/MHD, heat and mass transfer of reactor coolants and liquid breeders (He, liquid metals, water) Key Scientific Questions: • Can effective heat transfer be achieved with high temperature fusion coolants within the constraints of material temperatures and stress limits, plasma conditions and off-normal events, and tritium breeding requirements? • What is the combined impact of cooling schemes, component loads, and material and fabrication choices on the corrosion/erosion of structures and functional materials and the transport of activated material and tritium throughout the system More Detailed Examples: • Understanding and predicting high pressure helium heat transfer enhancement and resulting pressure drops at coolant/wall interfaces (impinging He jets, wall roughness, nano-porous media enhancement, etc.) • Local heat/mass transfer changes in liquid metal blankets where highly peaked nuclear heating leads to strong temperature gradients and buoyancy-driven unstable secondary MHD convection that competes with forced flow MHD convection • Impact of galvanic currents and highly sheared velocity profiles from MHD effects on local corrosion characteristics of both metal and ceramics 2/26 by NBM

  21. Power Extraction Issue 1:Thermofluid/MHD, heat and mass transfer of reactor coolants and liquid breeders (He, liquid metals, water) • Where are we at? • Water cooled PFC and Blanket components heavily studied for ITER, fission, and non-nuclear applications (TRL ~6 after ITER operation) • He and other gas coolants have been studied for fission and non-nuclear applications, but very high surface heat flux and complex blanket flow geometries are somewhat unique to fusion. (Current TRL ~3-4) • Basic flow and heat transfer experiments underway with He, Air for PFC and Blanket geometries • Larger firstwall/blanket mockup experiments with RAFS are being developed for testing in the EU/JA and then ITER TBM (increase Blanket TRL ~5 after ITER TBM testing, but not in the US) • Commercial CFD codes appear capable of predicting heat transfer performance, and to a lesser degree pressure drop • MHD effects in liquid metals are largely unique to fusion. (TRL ~3) • Surrogate LMs used to study MHD pressure drop, flow and (to a lesser degree) heat transfer phenomena in basic geometries and mockups. • Lithium and PbLi corrosion experiments with prototypic test material have been performed, but largely w/o B field in turbulent flow environments,and without prototypic multi-material effects 2/26 by NBM

  22. Power Extraction Issue 1:Thermofluid/MHD, heat and mass transfer of reactor coolants and liquid breeders (He, liquid metals, water) What are the gaps to Demo (examples): • For LM in particular, coupled volumetric heating and magnetic field interactions at reactor scale dimensionless parameters (requires both strong volumetric heating and strong magnetic field) • Tritium transport and corrosion phenomena and chemistry control techniques in multi-effect, multi-material environments with prototypic materials; flow and temperature distributions • Multi-physics models capable of simulating multi-effect experiments and synergistic phenomena reaching fusion relevant dimensionless parameters • Component and system level, prototype integrated testing for all coolants and PFC/Blanket concepts in relevant to prototypic environments • Impact of changes in properties with neutron irradiation on both heat and mass transfer (degradation of thermal conductivity, modification of surface processes, electrical changes in MHD insulators, formation of bubbles in liquid breeders,etc.) • Techniques in gas cooling to extend significantly above 10 MW/m2 • Alternatives to gas cooling in PFCs at high temperatures, e.g. liquid metal coolants and free surface liquid metal PFCs 2/26 by NBM

  23. Power Extraction Issue 1:Thermofluid/MHD, heat and mass transfer of reactor coolants and liquid breeders (He, liquid metals, water) What is needed: Skills, testing facilities, diagnostics • All the above… 2/26 by NBM

  24. Power Extraction Issue 2:Fabrication/assembly of complex components and coolant loop systems from reduced activation materials Integration of component engineering design with detailed assessment of materials processing/ fabrication requirements together with methods for assembly, joining and inspection. Development of models that link processing/fabrication variables to component structures at various length scales; a) component shapes and residual stresses, b) macro-scale defects such as porosity and inclusions, and c) start-of life microstructures that mediate mechanical performance and dimensional stability. 2/23 by NBM

  25. Power Extraction Issue 2:Fabrication/assembly of complex components and coolant loop systems from reduced activation materials Development of cost–effective fabrication and high- fidelity joining technologies for the construction of complex in-vessel components utilizing reduced activation materials, and ensuring satisfactory physical and mechanical properties of all joints, including irradiation performance. Achieving the required start-of-life microstructures and meeting the specified engineering tolerances in components subjected to multiple heat treatment cycles associated with each joining stage, represent major materials-engineering challenges. Specialized non-destructive examination techniques need to be developed and qualified to accommodate the unique complexities of blanket structures 2/28 by AR

  26. Power Extraction Issue 2:Fabrication/assembly of complex components and coolant loop systems from reduced activation materials 1. Demonstrate the fabrication and assembly of complex in-vessel components utilizing partnerships with industrial vendors to identify and develop reliable fabrication, joining, assembly and inspection methods Research/technical needs: Establishment of large-scale production methods for all materials (structural, heat sink, plasma facing,) in the required geometrical forms and at the required levels of impurity control. Development of reliable, robust joining methods for all structural materials utilizing a comprehensive range of technologies including TIG, laser and EB welding, diffusion bonding, pressure welding, hot isostatic pressing, ultrasonic welding, and friction stir welding Determination of the mechanical an physical properties of joints including demonstration of satisfactory irradiation performance Development of specialized NDE techniques to meet the unique requirements of blanket structures and complex joint geometries Efficient integration of the component design process with the parallel development of cost-effective fabrication, assembly and inspection methods 2/28 by AR

  27. Power Extraction Issue 2:Fabrication/assembly of complex components and coolant loop systems from reduced activation materials 2.Development of a science–based understanding of the fabrication technologies and the development of processing models to predict the impact of fabrication/assembly on the properties of the materials and on the performance of the assembled component Research/technical needs: Development of a comprehensive understanding of the materials science of the fabrication processes involved for each material (casting/solidification, deformation, recovery, recrystallization grain size control, heat treatment cycles, segregation and phase transformations). Establish an understanding of processing–microstructural relationships at each stage of fabrication and joining to ensure that in the final component, all materials are in their required start-of-life microstructural condition at all length scales with the specified physical and mechanical properties  Modelling of residual thermal stress distributions induced during welding/joining procedures and also during heat treatment cycles Develop predictive models of the effects on component integrity of various macro-scale defects induced during fabrication including the distribution of residual porosity, non-metallic inclusions and micro-cracks.. 2/28 by AR

  28. Power Extraction Issue 3:Diagnosis, monitoring and control of blanket and primary cooling loop operation 2/23 by NBM

  29. Power Extraction Issue 4:Effective radiation shielding of vacuum vessel, magnets, and personnel • Key Scientific Questions: • Can we efficiently recover the ~10% of the fusion power deposited in the shield? • Can we accurately characterize the nuclear field and environment for radiation sensitive components and personnel behind the thick and geometrically complex blanket/shield? • More Detailed Examples: • Understanding and predicting compatibility conditions for shielding materials and coolants with attractive shielding performance • Defining temperature windows for effective shielding materials with impact on overall power cycle efficiency • Well defined and validated radiation limits for vacuum vessel, magnets, and other radiation sensitive components • Accommodation of solutions for reducing radiation streaming (e.g. stepped gaps) with possible hot spots and impact on maintenance • Adequate shielding around penetrations for plasma heating and current drive and diagnostics • Accurate modeling of the heterogeneous blanket/shield design • Adequacy of nuclear data for accurate prediction of radiation fields 2/23 by NBM

  30. Power Extraction Issue 4:Effective radiation shielding of vacuum vessel, magnets, and personnel • Where are we at? • Due to relatively large power deposited in shield, heat needs to be recovered and integrated in power cycle. Same coolant used in blanket (PbLi, He, H2O) is preferred and is required to run at relatively high temperature. Shielding materials used are primarily SS, W, WC, B4C, and Pb. Data on compatibility with coolant at relevant fusion environment is not available (TRL ~2) • Radiation or SS VV rewelding (~1 He appm) is well defined and validated (TRL ~6 after ITER operation). However, no data is available about reweldability limit for FS. Radiation limits for magnet conductors, insulators, and stabilizers were determined in fission reactor environment and are speculated to apply in fusion environment with harder neutron spectrum and lower gamma heating (TRL -6 after ITER operation) • FENDL-2.1 has been the reference fusion nuclear data library for 5 years. Validation using integral experiments show differences from experimental results of up to ~30% behind 80 cm thick ITER shield mock-ups. Activities to upgrade to FENDL-3.0 just started and will require experimental validation to insure improvement in accuracy (TRL ~4). Uncertainty due to nuclear data need to be reduced to <5% • Fusion systems are geometrically complex with large degree of  heterogeneity that should be modeled accurately in neutronics  calculations. Modeling approximation introduce significant  differences in predicted nuclear fields. An on-going activity allow using the exact CAD models in calculation to preserve geometrical details. Nuclear heating  distribution is affected significantly by heterogeneity and is  important for power extraction analysis. These tools under development need to be extensively validated with experiments (TRL ~ 3) 2/23 by NBM

  31. Power Extraction Issue 4:Effective radiation shielding of vacuum vessel, magnets, and personnel • Research needs to fill the gaps to DEMO: • Material program needs to address compatibility and temperature window issues for shielding materials under relevant fusion environment. Where??? • Experiments needed to determine radiation limits for VV and magnet components under relevant fusion nuclear environment. Fission reactors can be used with neutron spectrum tailored by surrounding sample with strong thermal neutron absorber (e.g., B) and gamma flux can be suppressed by surrounding sample with strong gamma absorber (e.g., Pb) • Update and validate nuclear data to provide <5% uncertainties in calculated nuclear field. The 14 MeV neutron sources at Frascatti (FNG) and JAEA (FNS) can be utilized. Experimental mock-ups representative of fusion blanket/shield expected in DEMO should be developed and tested • Develop neutronics computational tools that interact directly with CAD models. Both statistical and deterministic methods should be explored with possible coupling to improve accuracy of calculation. Experimental mock-ups should be used to validate the developed tools 2/23 by NBM

  32. Power Extraction Issue 5:Development and validation of integrated plasma chamber system predictive capabilities • Key Scientific Questions: • Can we speed up the design and analysis process and minimize the required experiments to prove designs of plasma chamber components and allow predicting accurate performance features for the geometrically complex fusion systems with many synergistic phenomena? • Can we explore the design space of related physical phenomena and develop knowledge about how these phenomena interact with each other with minimum reliance on expensive experiments? • More Detailed Examples: • Development and validation of integrated models and predictive capabilities simulating synergistic phenomena and performance in fusion in-vessel systems including: nuclear field and response functions, thermo-fluid MHD, heat/mass transfer, structural mechanics, electro-magnetics, chemical reactions, system thermal-hydraulics, etc. • Understanding and predicting how nuclear field distributions affect heat and mass transport and thermo-structural and electro-magnetic features. • Develop accurate model for predicting tritium permeation, inventory, residence time, transport through and removal from high temperature materials and coolant systems • Understanding the transport, deposition and dose of activated corrosion products, transmutation products, and tritium in the ancillary piping, HXs, pumps 2/23 by NBM

  33. Power Extraction Issue 5:Development and validation of integrated plasma chamber system predictive capabilities • Where are we at? • Many physical phenomena in plasma chamber components depend strongly on the detailed distribution of nuclear fields. An on-going activity allow using the exact CAD models in calculation to preserve geometrical details. These tools are under development need to be extensively validated with experiments (TRL ~ 3) • Some bullets about where we stand on modeling for other physical phenomena (T permeation, MHD, structural analysis, activated material transport) ??? • Coupling the individual tools using a common geometrical domain to efficiently streamline information between the different analysis tools. This requires significant effort since the computational meshes used for different physical analyses are very different in nature. This requires development of effective mesh adaptation techniques 2/23 by NBM

  34. Power Extraction Issue 5:Development and validation of integrated plasma chamber system predictive capabilities • Research needs to fill the gaps to DEMO: • Develop, improve, and benchmark individual physical phenomena computational tools (neutronics, activation, thermo-fluid, LM MHD, heat/mass transfer, structural mechanics, electro-magnetism, chemical reactions, etc.) to directly use a common geometrical representation (CAD) • Develop and validate an integrated computational simulation tool that couples the state-of-the-art analysis tools for individual physical phenomena and utilizes a single computer based geometric model (CAD). This requires significant improvements in system integration to deal with the complex interface between tools (e.g., mesh adaptation) 2/23 by NBM

  35. Power Extraction Issue 6:Characterization of synergistic effects, failure modes and lifetime in the fusion environment Issue definition- The DEMO needs to achieve an overall availability of 50% or greater. Because of the many subsystems in a fusion reactor, a particular subsystem like the blanket needs to achieve an availability of 90 % or greater. This high level of availability means a high level of component reliability (i.e. very low failure frequencies) and an adequate lifetime in the fusion environment (e.g. 10 – 15 MW-yr/m2. This availability requirement necessitates minimal replacement times - an issue discussed in a companion paper. Research needs - The main need is to be able to test fusion prototypical blanket components and materials in a fusion environment to develop the necessary database on component failure modes, reliability and lifetimes in a fusion radiation environment. There will also be need to test components and materials in test facilities that simulate some of the critical conditions of the fusion environment. 2/23 by NBM

  36. Power Extraction Issue 6:Characterization of synergistic effects, failure modes and lifetime in the fusion environment Gaps - At present it is not possible to test candidate blankets or materials in a fusion environment. ITER will provide an opportunity to test components but with rather modest wall loadings and low fluence levels. This will not be adequate to develop the reliability, failure mode and lifetime data needed for DEMO. There is a need for a high fluence neutron source for developing the required materials property database and a fusion neutron test facility to test components But such facilities will not be available for another decade or two. Thus, in the near term there is a pressing need for using and upgrading test stands that provide separately and in combination the necessary levels of surface heat flux, bulk heating, magnetic fields and structural loadings; these studies will facilitate the development and qualification of large-scale multi-physics structural and safety codes in preparation for component testing in an intermediate neutron facility. Predictive multiscale models of materials behavior in the fusion environment need to be developed in conjunction with surrogate materials testing in fission and spallation neutron source facilities. 2/23 by NBM

  37. Key Scientific Questions Can robust component designs be developed to meet Demo availability goals (>50%)? Can component designs be developed that allow rapid replacement and repair More Detailed Examples Fission and fossil plant availability is ~90% Fusion “system” availabilities need to be over ~99% to provide overall plant availability of 90% (Cadwallader, 2007) Component designs must consider remote handling requirements - accommodate multiple fluid systems, tritium contamination, high radiation fields, etc. that will exist in the plasma chamber systems Components will need to be designed to minimize amount of remote operations necessary for removal and replacement, and allow efficient handling processes (weight, volume, geometry, connections, etc.) A key relationship exists between replacement times and component reliability --  the longer the replacement time for a particular component (mean time to replace) the more demand on that component's level of reliability (mean to to failure).  A component that has very long replacement times therefore must have extremely high degree of reliability. Where are we? ITER calendar availability ~10% ITER Blanket Modules and Diverter Water cooled – Demo expected to be gas or LM cooled ITER TBM Port installation is non-prototypic of Demo components ITER remote maintenance not optimized for in-vessel component replacement JET only fusion facility that has applied remote handling technology to an appreciable extent Power Extraction Issue 7:Identification and integration of maintenance and replacement methods 2/23 by NBM

  38. Power Extraction Issue 7:Integration, maintenance, and replacement methods for plasma chamber systems • What are gaps to Demo • Significant improvement in availability will be needed to meet Demo goals • Robust component designs required to extend useful life (TRL – 4-5) • Materials, thermal, structural, etc. • Integrated remote handling and power extraction component design process required to minimize change out times (TRL – 4-5) • Component designs compatible with hot cell and transport systems to minimize repair times (TRL-4-5) • Reliability data will need to be developed that will require extensive test campaigns. A wide variety of test stands will be needed to develop this as well as failure mode data • Component reliability and failure mode data under prototypic or near-prototypic conditions and configurations will be needed to assure Demo availability requirements are met (TRL – 3-4) • A fundamentally different approach to maintenance may be needed than is used in ITER.  We need to explore at the conceptual level many approaches to maintenance. • Skills, testing facilities, diagnostics • Visualization systems necessary to virtually test design and remote handling options • Small scale facilities will be necessary to test equipment at the subcomponent level – draining systems, joining, leak testing, etc. • Facilities will be necessary to test remote handling of full scale components and allow “practicing” • Prognostics and diagnostics available to identify imminent component failure • Ex-reactor testing and accelerated test programs will be needed to characterize reliability of specific sub-components • Fusion facility designed to produce prototypic or near-prototypic full fusion environment including fluences, fields, operational times, etc. will be needed to validate component reliability 2/23 by NBM

  39. Power Extraction Issue 8:Efficient power conversion systems for electricity and hydrogen production including compatible heat exchangers • What are gaps to Demo • Potential operating temperature falls between high end of potential Rankine and lower end of efficient Brayton systems • Development of efficient Brayton systems will require development of low cost, efficient heat exchange systems for IHX (TRL-7) , intercoolers (TRL-7), recuperators (TRL-7), and reheaters (TRL-4) • Development of efficient Rankine systems will requrie high pressure operation (~4500 psi) and multiple reheat stages (TRL-9) – these designs exist in fossil plants, and development will continue in fossil program – coupling of high temperature gas primary system to supercritical boiler may be a materials and design challenge (TRL-5-6) • Demo will need to couple multiple temperature and potentially multiple fluid systems used in blanket modules and diverter cassettes • Understanding of the tritium transport processes through heat exchange systems will need to be developed for appropriate temperature and materials combinations • Efficient hydrogen conversion efficiency has not been proven at prospective Demo temperatures • Skills, testing facilities, diagnostics • Coupled CFD/thermal/structural analysis capability needs to be developed and applied to HX equipment development and design • Testing of boilers, IHX, recuperators, etc. at prototypic conditions will be required to develop effective designs. • Testing of power cycle will be required if unique designs must be developed to meet efficiency requirements • Long term testing of heat exchange equipment and power conversion system will be required to develop reliability data – accelerated testing programs are possible 2/23 by NBM

  40. Power Extraction Issue 9:Interaction of chamber systems with plasma operation Detailed Example • Surface Interactions in High Temperature divertor and first wall: The front surface of the plasma chamber system interacts directly with the fusion plasma. The materials and operational characteristics of this front surface must enable effective plasma operation, extract high heat fluxes, survive erosion, and allow effective tritium breeding. • Erosion, Tritium Trapping, Power transmission and conduction to coolant, Precision Alignment Surfaces, Heat/particle fluxes survivability during fault conditions and fast plasma shutdowns • Blanket System interactions:The blankets proper are hidden from direct plasma interaction by the front surface but include an integrated first wall and couple electromagnetically with the plasma and plasma control. • Electromagnetic Forces From Disruptions, Passive Stabilization Structures, Control Coils Behind the Blankets, Error fields from the Blankets and large ports 2/27 by NBM

  41. Power Extraction Issue 9:Interaction of chamber systems with plasma operation Research Needs Erosion and neutron resistant materials must be tested. impurities are a source of radiation that can reduce peak heat flux to the divertor.  Reducing this peak heat flux to engineerable levels or finding new engineering solutions for both steady and short fault conditions  A major engineering challenge is how to accomplish alignment this with the sector maintenance scheme necessitated by superconducting toroidal coils. Demo relevant solutions to disruption resistance or avoidance However the force loads on the front surfaces are an issue in that handling them also motivates thick surfaces which compete against the necessary heat transfer and effective tritium breeding.   engineering solutions to how to accomodate the necessary toroidal electrical interconnects from sector to sector. These connections also most be taken into account in the force issues above.   Development is needed for embedded control such coils; they may have to use ceramic insulators.  Large port penetrations where there is no ferritic steel will constitute an ferritic steel “hole” which will produce the same kind of localized field perturbation as the TBMs in ITER. Means to deal with this will need to be developed. 2/27 by NBM

  42. Power Extraction Issue 10:Interaction of plasma chamber system with tritium breeding functions and fuel cycle requirements • Key Scientific Questions: • Can we understand and define with enough confidence the conditions for plasma chamber components to ensure that we can breed enough tritium and close the fuel cycle? • How will these conditions impact the ability to efficiently extract power from chamber components? • More Detailed Examples: • Understand how tritium breeding in the blanket is impacted by material choice and amount of neutron absorbing material used • Accommodation of plasma control systems (e.g, stabilizing shells) and plasma heating and current drive systems in the chamber that are adequately cooled with minimal impact on tritium breeding • Provide adequate cooling for plasma facing components with materials yielding low tritium inventory and minimal impact on tritium breeding • Chemical control systems development for liquid metal chemistry and lithium-6 enrichment, and purge/coolant gas chemistry and tritium cleanup • Development of tritium removal system (permeator primary choice) and material choice with adequate performance for 700C PbLi systems • How do impurities introduced in environment impact tritium recovery system performance 2/23 by NBM

  43. Power Extraction Issue 10:Interaction of plasma chamber system with tritium breeding functions and fuel cycle requirements • Where are we at? • Several simplified neutronics models were used to assess impact of material choice on tritium breeding. These need to be done with detailed geometrical heterogeneity and realistic conditions and should be validated with experiments (TRL ~ 3) • MORE on tritium permeation, cooling issues ??? • Detection techniques do not exist to measure and manage tritium under high temperatures, high neutron flux, and high gamma fields expected in Demo 2/23 by NBM

  44. RENEW THEME IV WORKSHOP Power Extraction Panel Preliminary Research Thrust Ideas Robust operation of blanket/firstwall and divertor systems at temperatures suitable for efficient power conversion PANEL MEMBERS:Neil Morley, Charlie Baker, Pattrick Calderoni, Richard Nygren, Arthur Rowcliffe, Mohamed Sawan, Ron Stambaugh, Grady Yoder UCLA, March 2-4, 2009

  45. Greenwald Report on Initiatives • While there are definitely “single-effect” data still needed, don’t limit I-7 to just single-effect science • Focus 1-9 on preparation and execution of partially-integrated, to fully integrated environment/function experiments • Rename I-10 based on the knowledge gap, and not the facility I-7 Engineering and materials physics modeling and experimental validation initiative - a coordinated and comprehensive research program I-9 Component development and testing program - coordinated research and development for multi-effect issues in critical technology areas I-10 Component qualification facility

  46. A Framework for Fusion Nuclear Science and Technology Development Theory/Modeling Design Codes, Predictive Cap. 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, plasma physics devices) Testing in Fusion Facilities

  47. Suggestions for overarching and “granular” thrusts Building a fusion nuclear science and technology capability: An integrated R&D and engineering design program • Single- (especially for LMs) and multiple-effect database • Validated predictive capability sufficient to proceed to design and interpret partially-integrated and integrated experiments • Increase FNST human resources, research capability, and expertise • Granular Thrusts Examples: • RAFS, W fabrication methods and properties • Tritium transport and removal in the PbLi power extraction system • Chemistry and isotope control in coolant/breeder/purge flow streams • Ceramic breeder unit cell thermomechanics and neutronics • Integrated modeling platform for multi-effect simulation • Component level engineering design and analysis center • High payoff alternatives – liquid surfaces, W structure, ... • …

  48. PeX Suggestions for overarching and “granular” thrusts Survive and thrive in the fusion environment: Fusion break-in FW/blanket, material, diagnostics performance experiments • Partially- and fully integrated effect, failure, and reliability database • Validated predictive capability sufficient to proceed to design and interpret moderate fluence, long exposure experiments • Use test stands, fission reactors, plasma devices, ITER TBM (first ~10 years, HH->DT) and FNF initial operation (if available) • Granular Thrusts Examples • Fusion environment tolerant diagnostic capability • Partially-integrated mockup and prototype qualification testing • Virtual TBM: system wide modeling and validation • Prompt and cyclic fully integrated thermomechanical and thermofluid MHD responses • Corrosion and tritium transport in integrated blanket systems (early life) • Functional impact of radiation damage in ceramics (early life) • …

  49. PeX Suggestions for overarching and “granular” thrusts Engineering feasibly and reliability of the fusion power components: establishing tritium self-sufficiency and continuous high grade heat extraction for fusion • Middle-life, fully integrated effect and reliability database • Validated predictive capability sufficient to design first Demo • Requires a new Fusion Nuclear Facility with long pulses, moderate NWL and fluence, and significant testing area and flexibility • Granular Thrusts Examples • Fusion material and component function response to fusion specrum irradiation (middle-life) • Multi-module interactions with common support and cooling systems • Validation of the principles of tritium self-sufficiency in complete system • Long pulse current drive and fueling in fusion environment • Failure modes, effects, rates and mean time to repair for random failures and planned outage (all in-vessel components) • Iterative design / test / fail / analyze / improve programs for reliability growth and safety (all in-vessel components) • …

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