Institute of Advanced Energy Kyoto University High Temperature

Institute of Advanced Energy, Kyoto University High Temperature Blanket and Its Socio-Economic Issues Satoshi Konishi Institute of Advanced Energy, Kyoto University Contents - Fast track and Development Strategy in Japan 　- Power plant design - Hydrogen production - Safety and environmental impact

Fast Track : the next step Institute of Advanced Energy, Kyoto University Fusion study is in the phase to show a concrete plan for Energy. -Power plant design and strategy following ITER are required. Common understanding ・Resource constraint (Energy) ・Global warming problem (Environment) ・Growth in developing countries (Economy) Energy Demonstration in 2030? Combined Demo-Proto steps Technical feasibility Social feasibility Strategy varies in each Parties due to different social requirements.

Fast Track Discussion in Japan Institute of Advanced Energy, Kyoto University 2000 2010 Power Demo ITER Test Generation BPP Const. EPP module 1 High beta, long pulse Test Tokamak KEP EVEDA Const. New line 10 dpa/y RAF 2030 Concept. Design Const. TBM IFMIF 2020 In pile irradiation module 2 Evolution required In a same facility 20 dpa/y 1/2 irrad. Full irrad. Drawn from Fast track working group in Japan, 2002, Dec.

Socio-Economic Aspect of Fusion Institute of Advanced Energy, Kyoto University ・Future energy must respond to the demand of the society. ・Social and Economical feasibility of fusion depends on high temperature blanket and its feature. Government Public Government funding Fusion Development Outcome Generation Technically feasible Previous Programs Researchers’ viewpoint funding Fusion Other Energy Outcome/benefit Damage/cost/ ”Externality” Future Energy Social Supply Demand Socially Required Present Programs Social viewpoint

Power Plant Design Institute of Advanced Energy, Kyoto University Near Future Plants -Reduced Activation Ferritic steels (RAFs) are expected as blanket material candidates. -Considering temperature range for RAFs, 500 C range is maximum, and desirable for efficiency. -From the aspect of thermal plant design, ONLY supercritical water turbine is the available option From fire-powered plant technology. -No steam plants available above 650 degree C.

Flow diagram of indirect cycle Institute of Advanced Energy, Kyoto University Steam Generator Reheater Blanket Turbines 　Feed water heater （divertor heat） Tritiated water processing CVCS Feed water pump Booster pump

Thermal plant efficiency Institute of Advanced Energy, Kyoto University Direct cycle turbine train generates 1160 MW of electricity. Thermal efficiency is estimated to be 41%.

Comparison of Generation Cycles Institute of Advanced Energy, Kyoto University 　　　　　direct　　 indirect He gas 　　　 Main steam pressure　 25 MPa 16. 3 MPa 10 MPa Turbine temp. 500℃ 480℃ 500 ℃ Coolant flow rate　　 　1250 kg/s 1260 kg/s 1865 kg/s Vapor flow rate 1250 kg/s 1037 kg/s 908 kg/s Total generation 1200 MW 1090 MW 1028 MW Thermal efficiency 41. 4% 38. 5% 35. 3% Technical issues　　 tritium in　 steam expansion 　　　　　 coolant generator volume Othermal Plants: BWRs – 33% PWRs – 34% Supercritical Fire – 47% Combined gas turbine - >60%

Findings Institute of Advanced Energy, Kyoto University -Supercritical water cycles is desirable and possible (technically difficult). - No gas turbine system is effective in temperature ~500 C. - With steam generator, gas cooled is less effective than water. - Plant design limited above 650 C. High temperature material does not guarantee economy. Improvements may be required in the DEMO generation. Possible Advanced Plant Options -High temperature cycle can be planned with He gas turbine at ~900 C. -Only dual coolant Li. Pb blanket has possibility for high temperature in ITER/TBM. -At high temperature, use of heat for hydrogen production may be an attractive choice.

Fusion Contribution with hydrogen Gton oil equivalent/year Institute of Advanced Energy, Kyoto University 30 actual estimated renewables 20 nuclear Fusion hydrogen gas Fusion electric hydro Unconventional gas oil Unconventional oil 10 0 1900 Renewable hydroge coal 1950 2000 year 2050 2100

Hydrogen Production by Fusion Institute of Advanced Energy, Kyoto University Fusion can provide both high temperature heat and electricity - Applicable for most of hydrogen production processes As Electricity 　-water electrolysis, SPE electrolysis　: renewables, LWR 　-Vapor electrolysis : HTGR As heat 　 -Steam reforming: HTGR(800 C), -membrane reactor: FBR(600 C) 　 -IS process : HTGR(950 C) 　-biomass decomposition: HTGR 　　

Energy Eficiency Institute of Advanced Energy, Kyoto University ◯amount of produced hydrogen from unit heat 　 ・low temperature（３００℃）generation　　　 → conventional electrolysis 　 ・high temperature（９００℃）generation 　　　→ vapor electrolysis 　 ・ high temperature（９００℃） → thermochemical production 　 Hydrogen From 3 GW heat efficiencyelectricity Energy consumptionproduction 33% 1 GW 286 k. J/mol 25 t/ h 300 C-electrolysis 50% 1. 5 GW 231 k. J/mol 44 t/h 900 C-electrolysis 181 k. J/mol 56 t/h 900 C-vapor electrolysis 50% 1. 5 GW 900 C-biomass ー ー 60 k. J/mol 340 t / h

Use of Heat for Hydrogen Production Institute of Advanced Energy, Kyoto University ◯Processing capacity: 3 GWt 　 ・ 2500 t／h waste 340 t of H 2 　　 1. 3 x 106 fuel cell vehicles (6 kg/day) or 6. 4 GWe (70% fc) H 2 340 t/h Heat exchange, CO 2 3. 7 E+06 kg/h Shift reaction 2500 t/h biomass CO 2. 4 E+06 kg/h Fusion H 2 1. 7 E+05 kg/h Reactor H 2 O 3ＧＷｔｈ Chemical Steam cooler Reactor (770 t/h) He Turbine 1. 38 E+07 kg/h 600℃

Hydrogen from biomass and heat The experimental results of Amount of hydrogen the change in carbon production[mol] atoms combined in carbonized gases[mol. %] Institute of Advanced Energy, Kyoto University 30 25 CO 2 CH 4 CO 20 15 10 5 0 0. 0005 0. 0010 0. 0015 0. 0020 0. 0025 0. 0030 H 2 by calculation H 2 by measurement 35 65 4 85 35 flow rate steam concentration 65 [cm 3/min] 5 [%] 85

Fusion safety and environmental impact Institute of Advanced Energy, Kyoto University BLANKET REPROCESSING TURBINE GENERATOR HX BLANKET PLASMA FUELING WATER DETRITIATION RELEASE EXHAUST DETRITIATION SOLID WASTE BLANKET REPLACEMENT DECONTAMINATION OF SOLID WASTES TRITIUM EXTRACTION DISPOSAL EXHAUSTS EFFLUENTS PRIMARY LOOPS EVACUATION PURIFICATION STORAGE ISOTOPE SEPARATION LOADING IN/OUT 　①Solid Waste SECONDARY LOOPS: 100 g tritium Impact pathway ②Tritium Release from Coolant High temperature, pressure ③Fuel. Large Processing exhaust process RELEASE Out of primary enclosure

Inventory distribution compared with ITER OFF-SITE Institute of Advanced Energy, Kyoto University LOAD IN WASTE TEMPORARY STORAGE <100 g 〜 10 g WATER DETRITIATION ～ 1 g COOLANT ～ 1 g COOLING SYSTEMS HOT CELL 500 g STACK LOAD OUT EFFLUENT PROCESSING ～ 1 g EFFLUENTS <100 g FUELING 50 g VACUUM VESSEL 1100 g <100 g FUEL STORAGE 550 g* PURIFICATION 100 g TORUS EXHAUST 130 g 〜 10 g ISOTOPE SEPARATION 　 190 g PRIMARY FUEL SYSTEM ITER SITE INVENTORY： 2800 g POWER REACTOR：probably less

POWER BLANKET (example) Institute of Advanced Energy, Kyoto University 780 K supercritical water Li ceramic pebbles He/H 2 sweep for tritium recovery High Temperature High Pressure Fine tubings Tritium Production 1 st wall Cooling tubes Tritium Permeation could be ~100 g day

Normal release from Fusion Facility Institute of Advanced Energy, Kyoto University 　・ Normal tritium will be dominated by release from coolant 　・ Largest detritiation system will be for coolant 　・ Fusion safety depends on ACTIVE system. 　　　　　　 Generalized fusion plant building confinement secondary confinement GENERATION SYSTEM TRITIUM RECOVERY PRIMARY LOOP BLANKET PLASMA PRIMARY COOLANT PROCESSING reactor boundary SECONDARY LOOPS AIR DETRITIATION tritium flow tritium leak/permeation PRIMARY LOOP TRITIUM INVENTORY (kg) TRITIUM THROUGHPUT(kg/day) TOTALTHROUGHPUT (kg/day) COOLANTPROCESS 1 0. 5 30 0. 5 60 500000

Generalized detritiation system Institute of Advanced Energy, Kyoto University 　・Detritiation for power train will depends on blanket types. 　・Normal detritiation for coolant will handle emergency spill. 　・Safety control with active system is not site specific. 　　　　　　 Turbine Heat HX tritium Blanket tritium Heat Tritium recovery Low concentration Tritium recovery Large throughput Large enrichment Once through -broad concentration range Closed cycle cascade Tritium recovery High concentration Quick return

Detritiation systems of Plant Institute of Advanced Energy, Kyoto University Processes large throughput, lower concentration Controls environmental release Operational continuously (including maintenance) Air Detritiation : - 1000 m 3 / hour, possibly ci/m 3 level - leak from generator, secondary loops, hot cell Water Detritiation : (isotope separation) - 100 m 3 / day, possibly 1000 ci/m 3 level, 100 g/day? - driving turbine Solid Waste Detritiation : - 1 ton / day, possibly g / piece? - materials (lithium, berylium, Steel) recycle - needed both for resource and waste aspects.

Tritium confinement Institute of Advanced Energy, Kyoto University TRITIUM IS CONFINED WITHIN ENCLOSURES AND DETRITIATION SYSTEMS Power train will be driven with tritium containing medium. High temperature blanket will require improved permeation control. BUILDING D ETR ITIA TIO N S YS TEM VACUUM VESSEL Cryostat D ETR ITIA TIO N S YS TEM H X TUR B IN E Expansion pool Pressurized gas may require additional expansion volume. For gas driven system, large Expanson volume FUEL LOOP may be needed. Expansion pool

Emission Fusion and. University Dose Institute of from Advanced Energy, Kyoto Impact pathway of tritium suggests ingestion will be dominant.

Findings Institute of Advanced Energy, Kyoto University -Fusion plant detritiation will be dominated by power plant configuration. - Normal tritium release will be controlled actively. - Off-normal spill can be recovered with normal detritiation. - High temperature plant will require improved tritium system. -Measurable tritium will be released in airborne form. -Tritium accumulates in environment (far smaller natural BG). -Ingestion dose will be dominant. -For long run, C-14 may be a concern.

Conclusion Institute of Advanced Energy, Kyoto University Fusion development is in the phase to study market ・Fusion must find customers and meet their requests. ・Fusion must satisfy environmental and social issues. Development of advanced blanket is a key issue for fusion ・Economy - not just temperature, but to maximize market ・Environment - not just low activation, but best total cost and social value / least risk(Externality) Development strategy (road map) for blanket is needed. ・ITER and DEMO require 2 or more generations of blankets. ・staged improvement of blanket is planned with water-PB, and Li. Pb dual coolant concepts.

Conclusion 2 Institute of Advanced Energy, Kyoto University Possible blanket improvement ・Independent from large increment of plasma ・Continuous improvement can be reflected in blanket change. (Improvement in DEMO phase) ・Multiple paths to meet various needs are possible. ・Flexibility in development of entire fusion program is provided by blanket development. Fast Track