High Temperature Blanket and Its Socio-Economic Issues. Satoshi Konishi Institute of Advanced Energy, Kyoto University

Transcription

1 High Temperature Blanket and Its Socio-Economic Issues Satoshi Konishi Contents - Fast track and Development Strategy in Japan - Power plant design - Hydrogen production - Safety and environmental impact

2 Fast Track : the next step 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? Technical feasibility Combined Demo-Proto steps Social feasibility Strategy varies in each Parties due to different social requirements.

3 Fast Track Discussion in Japan Power Demo Concept Design Const. Test Generation ITER Const. BPP EPP TBM Tokamak IFMIF module1 High Test beta, long pulse KEP EVEDA Const. New line 10dpa/y 20dpa/y module2 Evolution required In a same facility RAF In pile irradiation 1/2 irrad. Full irrad. Drawn from Fast track working group in Japan, 2002,Dec.

4 Socio-Economic Aspect of Fusion 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 funding Fusion Development Outcome Generation Technically feasible Previous Programs Researchers viewpoint Government Public funding Fusion Other Energy Outcome/benefit Damage/cost/ Externality Future Energy Social Supply Demand Socially Required Present Programs Social viewpoint

5 Near Future Plants Power Plant Design -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.

6 Flow diagram of indirect cycle Steam Generator Blanket Reheater Turbines Tritiated water processing CVCS Feed water heater (divertor heat) Feed water pump Booster pump

7 Thermal plant efficiency Direct cycle turbine train generates 1160MW of electricity. Thermal efficiency is estimated to be 41%.

8 Comparison of Generation Cycles direct indirect He gas Main steam pressure 25MPa 16.3MPa 10MPa Turbine temp Coolant flow rate 1250kg/s 1260kg/s 1865kg/s Vapor flow rate 1250kg/s 1037kg/s 908kg/s Total generation 1200MW 1090MW 1028MW Thermal efficiency 41.4% 38.5% 35.3% Technical issues tritium in steam expansion coolant generator volume Other thermal Plants: BWRs 33% PWRs 34% Supercritical Fire 47% Combined gas turbine - >60%

9 Findings -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 LiPb blanket has possibility for high temperature in ITER/TBM. -At high temperature, use of heat for hydrogen production may be an attractive choice.

10 Fusion Contribution with hydrogen Gton oil equivalent/year actual estimated oil Renewable hydrogen renewables nuclear gas Fusion hydrogen hydro Fusion electricity Unconventional gas Unconventional oil coal year

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

12 Energy Eficiency amount of produced hydrogen from unit heat low temperature(300 )generation conventional electrolysis high temperature(900 )generation vapor electrolysis high temperature(900 ) thermochemical production From 3GW heat efficiency Hydrogen production electricity Energy consumption 300C-electrolysis 33% 1GW 286kJ/ mol 25t/ h 900C-electrolysis 50% 1.5GW 231kJ/ mol 44t /h 900C-vapor electrolysis 50% 1.5GW 181kJ/ mol 56t /h 900C-biomass ーー 60kJ/ mol 340t / h

13 Processing capacity: 3GWt 2500t/h waste 340t of H2 or 6.4 GWe (70% fc) Heat exchange, Shift reaction Fusion Reactor 3GWth Use of Heat for Hydrogen Production 1.3x10 6 fuel cell vehicles (6kg/day) Chemical Steam Reactor He (770 t/h) 1.38E+07 kg/h H2 340 t/h CO2 3.7E+06 kg/h 2500 t/h biomass CO 2.4E+06 kg/h H2 1.7E+05 kg/h H2O cooler Turbine 600

14 Hydrogen from biomass and heat CO 2 CH 4 CO The experimental results of the change in carbon atoms combined in carbonized gases[mol.%] H 2 by calculation H 2 by measurement Amount of hydrogen production[mol] flow rate [cm 3 /min] 4 5 steam concentration [%]

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

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

17 POWER BLANKET (example) 780K supercritical water Li ceramic pebbles He/H2 sweep for tritium recovery High Temperature High Pressure Fine tubings Tritium Production 1st wall Cooling tubes Tritium Permeation could be ~100g day

18 tritium leak/permeation Normal release from Fusion Facility Normal tritium will be dominated by release from coolant Largest detritiation system will be for coolant Fusion safety depends on ACTIVE system. GENERATION SYSTEM building confinement PRIMARY COOLANT COOLANT PROCESS- ING AIR DETRITIATION TRITIUM RECOVERY tritium flow BLANKET PLASMA reactor boundary SECONDARY LOOPS Generalized fusion plant secondary confinement PRIMARY LOOP TRITIUMINVENTORY(kg) TRITIUMTHROUGHPUT(kg/day) TOTALTHROUGHPUT(kg/day) PRIMARYLOOP COOLANTPROCESS

19 Generalized detritiation system 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. HX Blanket Turbine tritium tritium Heat Heat Heat Heat Tritium recovery Low concentration Large throughput Once through Tritium recovery Large enrichment -broad concentration range Closed cycle cascade Tritium recovery High concentration Quick return

20 Detritiation systems of Plant Processes large throughput, lower concentration Controls environmental release Operational continuously (including maintenance) Air Detritiation : 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, 100g/day? - driving turbine Solid Waste Detritiation : - 1 ton / day, possibly g / piece? - materials (lithium, berylium, Steel) recycle - needed both for resource and waste aspects.

21 Tritium confinement TRITIUM IS CONFINED WITHIN ENCLOSURES AND DETRITIATION SYSTEMS Power train will be driven with tritium containing medium. BUILDING DETRITIATIO N SYSTEM VACUUM Cryostat VESSEL DETRITIATIO N SYSTEM High temperature blanket will require improved permeation control. Pressurized gas may require additional expansion volume. Expansion pool HX TURBINE FUEL LOOP Expansion pool For gas driven system, large Expanson volume may be needed.

22 Emission from Fusion and Dose TRITIUM FACILITY NORMAL/ ACCIDENTAL TRITIUM RELEASE WIND DIFFUSION PLU ME ATMOSPHERE HT ATMOSP HE RE HT O DRY DEPOSITION SURFACE SOIL SHALLOW SOIL W ET DE POSITIO N WASHOUT SURFACE WATER PLANT HTO PLANT OBT FISH GRAZING ANIMAL GRAZING ANIMAL HTO OBT DE EP S OIL INHALATION SKIN ABSORPTION DRINKING WATER HUMA N BO DY HTO INJ ES TI ON HUM AN BO DY O BT TRITIUM BEH AVIOR TO C AUSE HUMAN DOSE EFFECTIVE DOSE EQUIVALENT DOSE EFFECT Impact pathway of tritium suggests ingestion will be dominant.

23 Findings -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.

24 Conclusion 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 LiPb dual coolant concepts.

25 Conclusion 2 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. EXPERIMENTAL REACTOR (ITER) Q=10 500sec β N=2.5 BLANKETS GAS METAL PLASMA DEVICE DEMO REACTOR Q=30 STEADY β N~3.5 Fast Track SUPER CRITICAL GENERA TION EFFICIENT COOLANTS INDUSTRIA L HEAT COMMERCIAL REACTOR EFFICIENT GENERA TION MARKET SELECTION Flexibility in development of entire fusion program is provided by blanket development. SHIELD WATER MATERIALS NEUTRON USE Ferritic Steel SiC/SiC Vanadium