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Overview of DCLL R&D and Predictive Capability Activities Compiled by Neil Morley of UCLA 2006 US-Japan Workshop on Fusion High Power Density Components and System Inn on the Alameda, Santa Fe, New Mexico, USA November 15-17, 2006
Outline • R&D Strategy and Prioritization • Main DCLL R&D Categories • Introduction to Predictive Capabilities • Summary
R&D tasks directly contribute to satisfying design, qualification, safety, and operation requirements R&D tasks have been reviewed based on: • Forming basis for important design, material, and fabrication decisions • addressing safety issues and reliability risks that must be resolved for qualification of the first TBMs • planning, operating and analyzing US TBM experiments in ITER ITER TBM Acceptance Requirements TBMs must not interfere with operation, availability, or safety TBMs must be Tested in H-H Phase TBMs must be DEMO Relevant
ITER & DEMO requirements and risks have a strong impact on TBM design and R&D decisions • DEMO relevance: • Materials and fabrication techniques should extrapolate to radiation environment • TBM designs and loading should extrapolate to DEMO sizes and performance needs • Qualification, safety, and reliability requirements: • Intense and early R&D on RAFS fabrication • Inclusion of prototype fabrication and several partially integrated mockup tests • Verified predictive capabilities will be required to establish allowable operating points from safety perspective • TBM is an experiment, but must know a lot abut how it will behave • Testing TBMs in the ITER H-H phase: • H-H phase TBM should use prototypical D-T phase TBM materials, fabrications, and designs • Predictive capability must extrapolate H-H operating conditions to D-T phase TBM operation
R&D and Predictive Capabilities progress together - coordinated with design milestones Basic Properties Models and Theory Final DesignQualificationIntegrated Simulation Single/MultipleEffects Testing Simulation Codes Partially-Integrated Mockup Testing Integration and Benchmarking PrelDes Rev July Title3DesRev StartPrototype June Prototype Done April FinDes Chng Dec FabRoute Dec BidPack August DetDesFinalRev Sep StartTBMfab June FY2008 2009 2010 2011 2012 2013
DCLL R&D Tasks are included under 3 main WBS elements 1. US ITER Proj. DCLL R&D tasks vary considerably in cost and scope 1.8 US ITER TBM 1.8.1 DCLL 188.8.131.52 Test Module 184.108.40.206 Tritium Systems • Thermofluid MHD • SiC FCI Fabrication and Properties • SiC/FS/PbLi Compatibility & Chemistry • FM Steel Fabrication & Materials Prop. • Helium System Subcomponents Tests • PbLi/H2O Hydrogen Production • Be Joining to FS • Advanced Diagnostics • Partially Integrated Mockups Testing • Model Development and Testing • Fate of Tritium in PbLi • Tritium Extraction from PbLi • Tritium Extraction from He 220.127.116.11 Design Integration • He and PbLi Pipe Joints • VV Plug Bellows Design
Key DCLL R&D Items • PbLi Thermal fluid MHDKey impacts on thermal and power extraction performance • SiC FCI development including irradiation low fluence effectsKey impacts on DCLL lifetime, thermal and power extraction performance • RAFS/PbLi/SiC compatibility & chemistry Impacts DCLL lifetime and thermal performance • Tritium extraction and controlCritical element for high temperature PbLi such as in DCLL • High temperature heat exchangerCritical element for high temperature DCLL • He system subcomponents analyses and tests, He distribution and 1-sided heat transfer enhancementKey impacts on DCLL thermal and power extraction performance • RAFS fabrication development and materials properties including low fluence effectsCredibility of the RAFS structural material and DCLL design • Integrated Mockup leading to Test Blanket Module testing in ITERCredibility of the RAFS structural material and DCLL design
RAFS Fabrication – determine detailed material and fabrication specification Coordinated by R. Kurtz and A. Rowcliffe Produce H-H TBM that meet design specifications schedule, qualification testing and safety requirements, Basic Properties Single and Multiple Effects Testing Mockup fabrication support Partially-Integrated Mockup Testing • Material alloy specification • Fabrication procedures • Properties - base metal & joints Final Design Fabrication Qualification NDE tests and test procedures Irradiation effects StartPrototype June Init R&D Oct FabRoute Dec FY2007 2008 2009 2010 2011 2012
Fabrication discussions with US Industry have shown strong capabilities and interest
Partially-Integrated Testing is a key part of qualification of experimental components • Testing needed to: • demonstrate performance • provide “practice” fabrications • support safety/qualification dossier • data to verify Predictive Capabilities in complex geometry Basic Properties Coordinated by R. Nygren Single and Multiple Effects Testing • FW Heat Flux Tests • PbLi Flow and Heat Transfer Tests • Pressurization and Internal LOCA Tests Partially-Integrated Mockup Testing Final DesignFabricationQualification Existing US Facilities used in plan and cost estimate Title3DesRev StartPrototype June BidPack August DetDesFinalRev September PrototypeDone April FinDesChng December StartTBMfab June FY2008 2009 2010 2011 2012 2013
FCI development and Thermofluid MHD are highly inter-related DCLL R&D efforts Coordinated by Y. Katoh andS. Smolentsev Basic Properties • FCI and MHD together determine : • PbLi flow conditions and blanket temperatures / thermal loads • FCI required/achievable properties Single and Multiple Effects Testing FCI properties and fab. Partially-Integrated Mockup Testing • Modeling Tools • Manifold experiments • FCI flow and HT experiments • FCI irradiation • Simulation • FCI mockup Final DesignFabricationQualification Title3DesRev StartPrototype June PrelDesRev July FabRoute Dec BidPack August DetDesFinalRev September PrototypeDone April FinDesChng December StartTBMfab June FY2008 2009 2010 2011 2012 2013
FCI/SiC Devel. & Fabrication • Tailoring k and • k(T), (T) • Irradiation effect • Fabrication issues SiC/SiC Flow Channel Insert • Decoupling PbLi & Fe • Electric insulation • Thermal insulation • Low primary stress • Robust to thermal stress - T ~200C FCI is the key element of DCLL – its performance and fabrication must be explored prior to ITER testing Thermofluid MHD Structural Analysis ITER TBM • FCI stresses • FCI deformations • Effectiveness of FCI as • electric/thermal insulator • MHD pressure drop and • flow distribution • MHD flow and FCI property effects on T ITER DT MHD Experiments • 3D FCI features • Manifolds ITER DT: Max stress <45 MPa UCLA Manifold Flow distribution Experiment (~1m length)
FCI in DCLL Blanket Module • FCI is a key feature that: • Distinguishes DCLL blanket. • Makes DCLL concept attractive for DEMO and power reactors. • Two important FCI functions: • Thermally insulate Pb-Li so that the Pb-Li temperature can be considerably higher than the maximum operation temperature for steel structures. • Electrically insulate Pb-Li flow from steel structures.
Key Requirements to FCI • Adequate tranverse thermal insulation • Kth = 2~5 W/m-K for US DCLL TBM (assuming 5 mm FCI) • Adequate transverse electrical insulation • sel = 5~100 S/m for US DCLL TBM (assuming 5 mm FCI) • Chemical compatibility withPb-Li • Up to the highest possible temperatures, in a flowsystem with strong temperature gradients, andcontact with FS at lower temperature. • Hermeticity • Pb-Li must not “soak” into cracks or poresin order to avoid increasedelectrical conductivity, high tritium retention, orexplosively vaporized pockets. • In general,sealing layers are required onall surfaces of the inserts. • Mechanical integrity • Primary and secondary stresses must not endanger integrity of FCI • Maintain 1-5 in a practical operation environment • Neutron irradiation in D-T phase • Developing flow conditions, temperature & field gradients • Repeated mechanical loading upon VDE and disruption events
Tyranno-SA/PyC/FCVI SiC/SiC as FCI Material • SiC/SiC has been identified to be the most promising material for FCI • Industrial maturity, radiation-resistance, chemical compatibility, etc. • Being qualified as the control rod material in US-DOE Next Generation Nuclear Power program.
Why are Differential Swelling and Creep Important for FCIs? • Low temperature swelling (S) in SiC • Occurs at < ~1000ºC • Negative correlation with temperature • Start at onset of irradiation • Saturate by ~1 dpa • Differential swelling (dS/dT·dT/dx) • ~twice more significant than CTE • Unconstrained strain reaches 0.1%, typical unirradiated fracture strain for SiC, at DT = 120K. • Irradiation creep may eliminate the secondary stress issues • Transient irradiation creep strain exceeding 0.2% is reported for SiC. • Strong swelling-creep coupling likely exists. • No data available. ~8x10-6 K-1 Irradiation temperature-dependence of saturated swelling in SiC
Transverse electrical conductivity measurements in 2D composite 2D SiC composite,in-plane Monolithic SiC DCLL TBM Target 2D SiC composite,transverse • Data for in-plane of typical fusion grade 2D-SiC/SiC shows relatively high values ~500 S/m, likely due to highly conducting carbon inter-phase • New measurements on same material shows SIGNIFICANTLY lower in transverse direction – 2 to 3 orders lower at 500C • The low transverse apparently reflects the extreme anisotropy of the CVI-deposition process for SiC/SiC composite made with 2D-woven fabric layers. • Thermal conductivity still a challenge DC electrical conductivity measurements of 2D-Nic S/CVI-SiC composite. Measurements were made in both argon-3% H2 or dry argon. Vacuum-evaporated Au-electrodes on disc faces.
Approach & Potential Design Benefits of SiC Foam for flow channel inserts • Ultramet will fabricate a flow channel insert composed of an open-cell CVD SiC foam primary structure with thin, integrally bonded and impermeable CVD SiC facesheets. • Improved manufacturability and lower cost compared to SiC/SiC • High strength, stiffness, and thermal stress resistance • Lower thermal conductivity than SiC/SiC CVD SiC closeout layers applied to SiC foam (5X) ULTRAMET-DMS proposed Flow-Channel Insert configuration
Testing of foam samples in role as flow channel inserts • Disk samples (~70 mm diameter) held in contact with LM on both sides • 100 C thermal gradient and variable electric current applied to the sample • Measurements of electrical and thermal conductivity as a function of thermal cycles • Looking for penetration of LM into SiC Testing rig at UCLA
Summary of electrical and thermal conductivity measurements on SiC foam in contact with LM – no penetration observed in 100 h tests
Test Li Si C O N Starting n.d. <40 <170 1270 <40 1000 h 800°C 17.49% <30 1850 4090 100 1100°C 16.27% <30 1160 3550 90 1200°C 15.62% 370 2690 16620 450 2000 h 1100°C 15.99% 185 1025 7890 200 5000 h 800°C 18.55% <60 650 2580 90 Compatibility of SiC With PbLi at 800 - 1200°C Concentrations in appm Static Capsule Tests Outer SS, Inconel or 602CA Capsule Mo Capsule Mo Wire Spacer SiC Crucible & Lid • No significant mass gains after any capsule test. • Si in PbLi only detected after highest temperature tests. • Si could come from CVD SiC specimen or capsule. • Results suggest maximum temperature is <~1100°C • Research Needs: • Testing in flowing LiPb environment. • Testing of SiC composites with sealing layers. 17Li-Pb SiC Specimen Holder CVD SiC Specimen Al2O3 Spacer Before/During Test
Thermofluid/MHD issues of DCLL In the DCLL blanket, the PbLI flows and heat transfer are affected by a strong magnetic field Issues: • Impact of 3-D effects on pressure drop & flow distribution • Flows in the manifold region • Flows in non-uniform, 3-component ITER B-field • Pressure equalization via slots (PES) or holes (PEH) • FCI overlap regions • FCI property variations • Coupled Flow and FCI property effects on heat transfer between the PbLi and He and and temperature field in the FCI and Fe structure • Flow distribution, heat transfer, and EM loads in off-normal conditions DCLL DEMO B-field
Current DCLL design based on 2D fully developed Thermofluid MHD analysis • Characterization of the general MHD phenomena in the blanket • 2D simulations showing: • Effectiveness of the FCI as electric/thermal insulator • Preferred pressure equalization slot location on FCI • Preliminary identification of SiC FCI properties ( and k) • Estimates of the MHD pressure drop in the system MHD pressure drop reduction for different slot locations
Temperature. ITER DT High Ha number flow computation DEMO: Ha=15,000; Re=84,000; =100 S/m Current status of Thermofluid MHDR&D and PC (Cont’d.) • Preliminary 3-D heat transfer analysis for DEMO, ITER HH and DT blanket modules • Coupling between: - Thermofluid/MHD Structural Analysis - Thermofluid/MHD He Thermofluid • Good start on 3-D parallel MHD software (HIMAG) and a number of research codes addressing specific MHD/heat transfer issues
US strategy for DCLL Thermofluid MHD R&D Two goals: • To address specific 1st ITER TBM issues via experiments and modeling • To develop a verified PC, enabling design and performance predictions for all ITER TBMs and DEMO blanket Two lines of activity: • Experimental database. Obtain experimental data on key MHD flows affecting operation and performance of the blanket for which there is little/no data available. • Flow distribution in manifolds • FCI effectiveness and 3D flow issues • Coupled heat transfer / velocity field issues • Modeling tools. Develop 2D and 3D codes and models for PbLi flows and heat transfer in specific TBM/DEMO conditions. Benchmark against existing and new analytical solutions, experimental data and other numerical computations. • HIMAG – arbitrary geometry 3D fully viscous and inertial parallel MHD solver • 2D models and codes for specific physics issues – MHD turbulence and natural convection
z x y B Case-1 Bmax = 2.08 T Ha = 6640 N = 11061 Re = 3986 U = 0.07 m/s Case-2 Bmax = 1.103 T Ha = 3500 N = 770 Re = 15909.1 U = 0.2794 m/s 3D HIMAG Benchmark Case against Experimental Pipe Flow Data at Ha = 6600 t = 0.00301 m a = 0.0541m x = 15a x = -20a ( C.B.Reed et al, 1987)
Flow Streamlines with electric potential contours Pressure drop comparison to experimental data
Application of HIMAG to Manifold Problem • 3D complex geometry and strongMHD interaction – what isthe flow distribution?
MHD effects control the flow distribution due to M-shaped velocity profile formation Ha = 1000 Re = 1000 N = 1000
Center channel has larger flow • center channel+11.8% • side channels-5.9% • Dependence on Ha, Reand geometry must be studied – Likely to be more imbalanced at higher Ha Ha = 1000 Re = 1000 N = 1000
MTOR Laboratory at UCLA QTOR magnet and LM flow loop BOB magnet JUPITER 2 MHD Heat Transfer Exp. in UCLA FLIHY Electrolyte Loop
MHD Manifold Flow Distribution Experiment • ~1 m in length • Fits into BOB magnet with in-situ MHD pumping sections • Potential and pressure taps for measuring flow distribution and pressure drop • Potentially part of Jupiter III collaboration with Japan
Outflow RAFS wall 4 mm thick 2 mm gap z SiC wall 5 mm thick 5 mm y 1.66 m 1.4 m y x B z FCI Inflow 120 mm 0.139 m 139 mm 0.3 m DCLL Geometry (not to scale) for HIMAG Simulations
High Ha number flow computation DEMO: Ha=15,000; Re=84,000; =100 S/m 2D models for turbulence and mixed convection • Effects important for flows with strong temperature gradients, velocity jets and poorly conducting walls • Motions tend to become 2D at such high interaction parameter
A verified predictive capability is considered a top level deliverable for a TBM program Basic Properties A ultimate goal of R&D and ITER testing is to provide a verified Predictive Capability (PC) that can: • Meet ITER QA verification requirements • Perform the analysis required for the design and qualification of any TBM in ITER, and • Enable interpretation and extrapolation of experimental results from laboratory experiments and from ITER TBMs. Models & Theory - Final Design- Qualification- Integrated Simulation Single/MultipleEffects Testing Simulation Codes Partially-Integrated Mockup Testing Integration and Benchmarking PC Analogy: The TBM can be considered the hardware, and the Predicative Capability the software necessary to exploit the hardware
PC is included as a main branch of the WBS – similar to EU and other parties
“Models and codes” includes simulation codes and complex physical and solid models Turbulent fluctuations in DCLL flow channel in 18.104.22.168.2.1.1 ...both simulation codes, and sophisticated input and models for existing codes are included DCLL solid model showing manifold region geometry in 22.214.171.124.3.1
Predictive Capabilities tasks are linked to associated R&D and Engineering Analysis activities Predictive capability sufficient for design and qualification are important R&D tasks – as well as an important deliverable needed for TBM experiment operations Sample from PC Schedule: showing references to linked R&D tasks
Data/Code Integration, or Virtual TBM, is key for planning and interpreting ITER TBM experiments Integration of the various PC tools and data into an effective, coupled suite of capabilities that: • exchange data in a seamless and error-free manner, • are compatible with modern clusters and parallel execution • allow coupled simulation of the TBM experiments, including phenomena that are usually considered and modeled separately • Complex designs, CAD • neutronics, • coolant flow and heat transfer • structural response, • tritium breeding, permeation and extraction
Example Virtual TBM flow chart • Choosing analysis types (selection of codes) • Choosing CAD files for different analysis • Establish analysis hierarchy Selection Phase CAD inputs • Starting preprocessing modules for selected codes • Setting up different meshes, input files Preprocessor Phase • Setting up code interaction parameters and timing controls (How often to write load file, coordinate time steps between different codes) • Choosing between tandem run or sequential run between codes (preserving the analysis hierarchy) Interaction control • The required interpolation routines should start when mapping is required Solution Phase Grid mapping / Data Ex Post processing • Starting post processing modules for the different software. All results file at the same time level should be analyzed together • Some analysis parameters should be able to be changed at this stage and the solution recomputed from the current level to observe the change
Summary of the US TBM R&D / PC Activities and Technical Plan • The US TBM R&D plan is designed to provide the basis for important design, fabrication and qualification decisions. • R&D is needed to insure against risks to whole machine ($10B), not just this component - must be conservative! • If building one blanket module, or blankets for the whole machine, R&D is the essentially the same – subsequent TBM projects will be lower cost • A verified predictive capability is considered a top level deliverable • Main DCLL R&D activities include • RAFS fabrication and Partially-integrated Mockup Testing and prototypes make up >50% of projected costs • FCI development, and thermofluid MHD database and simulation tools • Other smaller activities in diagnostics, He thermofluid, PbLi compatibility and reactivity, and tritium