Engineering Design Evolution of the JT-60SA Project

Engineering Design Evolution of the JT-60SA Project P. Barabaschi, Y. Kamada, S. Ishida for the JT-60SA Integrated Project Team EU: F4E-CEA-ENEA-CNR/RFX-KIT-CRPP-CIEMAT-SCKCEN JA: JAEA 1JT-60SA Objectives •A combined project of the ITER Satellite Tokamak Program of JA-EU (Broader Approach) and National Centralized Tokamak Program in Japan. •Contribute to the early realization of fusion energy by its exploitation to support the exploitation of ITER and research towards DEMO. ITER DEMO Complement ITER towards DEMO Support ITER JT-60SA 2<ul style="display: flex;"><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li><li style="flex:1"> </li></ul>The New Load Assembly ••JT60-U: Copper Coils (1600 T), Ip=4MA, Vp=80m3 JT60-SA: SC Coils (400 T), Ip=5.5MA, Vp=135m3 JT-60U JT-60SA JT-60SA(A≥2.5,Ip=5.5 MA) ITER (A=3.1,15 MA) 3.0m 6.2m ~4m ~2.5m 1.8m KSTAR (A=3.6, 2 MA) 1.7m EAST (A=4.25,1 MA) 1.1m 3SST-1 (A=5.5, 0.22 MA) 3High Beta and Long Pulse • JT-60SA is a fully superconducting tokamak capable of confining break- max even equivalent class high-temperature deuterium plasmas (Ip =5.5 MA) lasting for a duration (typically 100s) longer than the timescales characterizing the key plasma processes, such as current diffusion and particle recycling. • JT-60SA should pursue full non-inductive steady-state operations with high βN (> no-wall ideal MHD stability limits). 44Plasma Shaping • JT-60SA will explore the plasma configuration optimization for ITER and DEMO with a wide range of the plasma shape including the shape of ITER, with the capability to produce both single and double null configurations. 55<ul style="display: flex;"><li style="flex:1">Ip=5.5MA, Lower Single Null </li><li style="flex:1">Ip=5.5MA, Double Null </li><li style="flex:1">Ip=4.6 MA ITER like </li></ul>Phased Research Plan • Exploitation within the BA period will aim at the initial research phase: - HH operation for plasma full commissioning - DD operation for identification of the issues in preparation for full DD operation • Principles of “Joint Exploitation” later phases agreed between EU and JA • Detailed “Research Plan” jointly prepared Annual Neutron Limit Expected Duration Remote Handling Max Power <ul style="display: flex;"><li style="flex:1">Phase </li><li style="flex:1">Divertor </li><li style="flex:1">P-NB N-NB ECRF </li></ul>1.5MW Power x Time 1-2 y 2-3y 2-3y >2y <ul style="display: flex;"><li style="flex:1">-</li><li style="flex:1">10MW </li></ul>x100s 23MW 33MW phase I phase II phase I phase II HDDDDInitial Research Phase LSN partial monoblock + 1.5MW x5s NB: 20MW x 100s 30MW x 60s duty = 1/30 4E19 4E20 1E21 R&D Perp. 13MW 10MW Tang. 7MW Integrated Research Phase LSN full- ECRF: 100s 37MW 41MW monoblock 7MW Use Extended Research Phase <ul style="display: flex;"><li style="flex:1">>5y </li><li style="flex:1">1.5E21 </li><li style="flex:1">DN </li><li style="flex:1">24MW </li><li style="flex:1">41MW x 100s </li></ul>6Baseline Schedule -Start of Tokamak Assembly: Early 2012 -Completion of Tokamak Assembly: October 2015 -First Plasma: Mid 2016. 7Device re-baselining • In late 2007, cost concerns prompted the Parties to request a re-design of the device. • Several ways to reduce costs were found in “old” design: • Issues found: ꢀMaximum field in TF conductor rather large for cost effective [email protected] design (Operation point : 6.5T at 5K, with 1K temperature margin). Conductor hot spot temp was unnecessarily low Structures rather heavy and complex to fabricate – multiple coil types Nuclear heating too conservatively estimated ꢀꢀꢀꢀ…• Solution: ꢀꢀꢀReduce TF field, decrease SC strands volume (segregation), decrease Cu section Optimise structural design Recover plasma performance lost by field reduction by plasma volume increase made possible by reduction of magnet size Rationalise requirements and ports ꢀ• In parallel some other problems were addressed: ꢀꢀꢀSeismic Loads to be managed by supports Peak TF Ripple in Plasma to be reduced to 0.5% Inductive flux for plasma operation to be increased to reach 100s flattop 8Design at >6T costly for NbTi (when Tcs~6K) T=6K T=5K 9Aspect Ratio Optimised •R/a is the real only free parameter in the design of a Tokamak for a given nTτ ••Trade-off between volume and power density R/a determines important engineering factors ꢀꢀꢀꢀꢀAccess to In-Vessel Components Wall power density Field and technology of magnets Mechanical loads Controllability of plasma shape •Optimum A is largely a function of technology, machine size, and scaling laws <ul style="display: flex;"><li style="flex:1">The Toroidal Field, and the density </li><li style="flex:1">increase with Aspect Ratio </li></ul><ul style="display: flex;"><li style="flex:1">decrease with Aspect Ratio </li><li style="flex:1">The Plasma volume the Plasma Current, and </li></ul>τE10 Main Results of re-Design on TF Magnet 2007 Design NEW IDR CDR 2007 2008 TF Total TF Energy [GJ] TF coils # 1.51 1.06 18 TF Tension [MN] Number of turns in 1 coil Peak Field [T] 6.80 90 4.70 72 6.43 30.0 5.65 <ul style="display: flex;"><li style="flex:1">24.4 </li><li style="flex:1">Total length of conductor [km] </li></ul>Total Structure Mass [ton] Strand type ~650 ~280 NbTi Conductor current [kA] Cable space dimensions [mm] N SC Strands 25.3 25.7 18x22 324 25.1x25.1 720 -<ul style="display: flex;"><li style="flex:1">N Cu Strands </li><li style="flex:1">162 </li></ul>Tmarg (after burn) [K] ~1.1 ~1.4 SC Strand mass in windings of 18 New Design <ul style="display: flex;"><li style="flex:1">92 </li><li style="flex:1">34 </li></ul>coils [ton] Segregated copper mass in 18 coils [ton] -14 11 Main Results of re-Design Additional Design Changes: •Cryoplant: heat load re-assessed based on new operation scenarios with reduced neutron yield and reduction of magnet cold structure. From 16kW to ~10kW and much improved dynamics •Cryostat: Single Wall with simplified geometry •Vacuum Vessel: Better distribute VV ports to provide a simpler out of plane support to the TF magnet structure. Reduction of shells •PF system: •Balance the distribution of turns in the EF system, •6 Coils (Vs 7), •Broader betap-li range, •28% less conductor •4 Independent CS coils (Vs 3) •TF Ripple Lowered: with Ferritic Insert will be <0.5% •Inductive Flux Increased: to ensure 100s flattop 12 Machine Parameters • After successful completion of the re-baselining in late 2008, the JT-60SA project was launched with the new design with the following parameters. Cryostat Basic machine parameters P-NBI P-NBI Plasma Current Toroidal Field, Bt Major Radius, Rp Minor Radius, a Elongation, κX Triangularity, δX Aspect Ratio, A Shape Parameter, S Safety Factor, q95 Flattop Duration Heating & CD Power N-NBI 5.5 MA 2.25 T 2.96 ECH 1.18 1.95 0.53 N-NBI 2.5 6.7 ~3 100 s 41 MW 10 MW 24 MW 7 MW 15 MW/m２ P-NBI ECRF Divertor wall load 13 13 Heating and CD Systems Variety of heating/current-drive/ momentum-input combinations NB: 34MWx100s Positive-ion-source NB 85keV 12units x 2MW=24MW COx2u, 4MW CTRx2u, 4MW Perpx8u, 16MW Negative-ion-source NB 500keV, 10MW for off-axis NBCD ECRF: 110GHz, 7MW x 100s 9 Gyrotrons, 4 Launchers with movable mirror 14 14 Magnet •All SC Magnet ꢀNb3Sn for CS ꢀNbTi for TF, EF •••18 TF Coils 6 EF Coils 4 CS independent modules 15 Conductors Coil Type of strands TF NbTi CS Nb3Sn 20 ~9 Operating current (kA) Nominal peak field (T) Operating temperature (K) Number of SC strands/Cu strands Local void fraction (%) Cable dimensions (mm) Central hole (id x od) (mm) Conductor ext. dimensions (mm) 25.7 5.65 <5K 324 / 162 32 <5.1K 216 / 108 34 TFC conductor 18.0 x 22.0 -22.0 x 26.0 Φ21.0 7 x 9 27.9 x 27.9 Conductor type No. of coils Type of strand EF-H EF3, 4 NbTi 20.0 6.2 EF-L EF1, 2, 5, 6 ←CS conductor Operating current (kA) Nominal peak field (T) Operating temperature (K) Number of SC/Cu strands Local void fraction (%) Cable dimensions (mm) Central hole (id x od) (mm) Conductor ex. dimensions (mm) ←4.8 <ul style="display: flex;"><li style="flex:1">4.8 </li><li style="flex:1">5.0 </li></ul>450 / 0 34 216 / 108 34 21.8 7 x 9 27.7 19.1 ←EF-L&H conductor 16 25.0 16 TF Magnet features TF winding pack Connections area • Cable in Conduit Conductor , 72 turns, 25.7kA each OIS • 6 double pancakes, 6 turns/pancake. Helium inlets in high field side – joints in external low field side EF1 hanging support arm • Windings enclosed in Steel Casings • Steel casings supported to ground vertically and toroidally - connected in inboard curved regions by “Inner Intercoil Structure” • Steel casings guided toroidally by “Outer Intercoil Structure” to support out of plane loads. EF support pedestals Gravity support Reinforcement ribs 17 View of Magnet - assembly 18 TFC Cold Tests •••All TFC will be cold tested at full current before shipping to Japan Test Facility will be in CEA-Saclay PA prepared with test facility specifications and cold testing specifications ꢀ HV Tests ꢀ Leak Tests ꢀ Flow, Pressure Drop ꢀ Dimensional Stability during and after cooldown ꢀ Resistance, Joints ꢀ Tmargin, Quench tests (2 coils) ••Cryostat and jigs being fabricated. Cryostat to be delivered in Saclay in first half 2011 19 Power Supplies •Largely a full new set of Power Supplies compatible with long pulse operation have been designed and will be procured. These will include: •TFC, grouped in 3 units of 6 coils ꢀ 6 pulse unidirectional, 26kA, 80V ꢀ 3 Fast Discharge QPC Units (1.5KV to ground) •PFC, each coil with: ꢀ 12 pulse, 20kA, ~1KV ꢀ Booster (old units) or new Switching Network Unit ꢀ Fast Discharge QPC Unit •In-vessel Coils ••QPC Units: Under final tendering phase SCM-PS: ꢀ Technical Specs completed, ꢀ Procurement Arrangement in final stage 20

Engineering Design Evolution of the JT-60SA Project

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