1. Satoshi Konishi Institute for Advanced Energy, Kyoto University May.25, 2005 A critical review and comparison of power reactor blankets from nuclear technology and socio-economic aspects Contents - Broader “Externality” aspect - Tritium release to the environment - Waste strategy - Fuel supply - Deployment to hydrogen market 7 th International Symposium on Fusion Nuclear Technology Special Thanks to Kunihiko Okano, Yusuke Ichimasa and Kenji Tobita

2. ・ Future energy will be evaluated by social preference. ・ Such evaluation will consider all the possible impacts and effects to future society and environment. Fusion Other Energy Outcome/benefit Energy Supply Damage/cost/ ”Externality” Future Social Demand Government funding Institute of Advanced Energy, Kyoto University Socio-Economic Aspect of Fusion Public Industry Different outcome are expected for sponsors.

3. How fusion affects? Plasma Blanket Facility Environment,Society Fuel, Material (D,Li-6,..) Generation Plant Heat Transfer Wastes (Solid nuclides, T,C-14) Exhausts (T,heat) (Recycle) Energy (Electricity) Fusion will be evaluated - what it consumes - what it exhausts - what it generates, and - what it leaves Blanket is the key For Socio-economic Feature of fusion Economy

4. － Energy sales is not the only outcome of the research. →”Externality” ; economical effect out of the market How fusion will benefit public? ・ Impact by various pathways -outside of energy market - estimated with economical value (monetary term) environmental negative ： pollution, global warming environmental positive ： recycling, cleaning, reduced emission social negative ： nuclear proliferation, terrorism, fear of risk social positive ： security, backstop, technology Energy positivenegative benefit security risk cost pollution warming cleaning recycle ・ All the risks and benefits ・ evaluated from the viewpoint of sponsor ・ market sales is only a part ・ cost is not a good measure but cost affects the market share social Environ.

5. ・ various sponsors provide funding ・ different purpose, different phase of development ・ investment for research is a certain fraction of total sales →investment must yield benefit to sponsors 1960 transfer ６．２％ For R&D industry utility Research institute Basic research Fission reactor case sales Further competitiveness improvements commercialization Research institutes Investment for nuclear technology

6. Temperature Thermal Efficiency coolant 300 500 800 Light water Heavy water 、 Liquid metal Molten salt Helium 30% 40% 50% NPD 1962 CalderHall 1956 CO2 FERMI 1963 （商用） Obninsk(RBMK) 1954 Shippingport PWR1957 VBWR 1957 EBR1 1951 AGR 1976 SGHWR 1968 EL-4 1966 Variety of fission reactors developed

7. Generations of blankets fit different phases - Fusion has multiple generations with single plasma 1) Technically possible. (liquid metal) 2) Governments policy and social preferences. (graphite, heavy water) 3) Market selection. (light water reactor) Strategies for blankets Each generations has different purpose. -expected functions of blanket differs. Learn from the history of fission.

8. 2000201020202030 Power Demo ITER TBM Tokamak IFMIF Const. BPP Test Generation EPP module1module2 High beta, long pulse KEP EVEDA Const. New line 10dpa/y20dpa/y RAF In pile irradiationFull irrad.1/2 irrad. Fusion development strategy Drawn from Fast track working group in Japan, 2002,Dec. Evolution required In a same facility Concept Design Const.Test The 1 st Blanket will aim at “earliest power generation”. Next target will be “deployment into the future society.

9. Energy Conversion Issue Steam ~ 500 ℃ or high temperature He ~ 900 ℃ Technology temperature efficiency use of heat Fossil fire Supercritical 600 ℃ 47% + Combined 1200 ℃ >60% + Fission LWRs 300 ℃ 33% - FBR 500 ℃ 40% +- Fusion Supercritical 500 ℃ 39-41% +- High T gas 900 ℃ 50% + Renewables rt - - Blanket heat transfer media will have to fit advanced energy.

10. mill/kWh 65 92 109 125 0 25 50 75 100 125 150 205020602070208020902100 year Possible Introduction price 145 Target cost of electricity varies as a function of Introduction time. Introduction into the market Possible introduction price of Fusion : increases with time as fossil price increases. Current target of the development year price technology resource renewable

11. Emission dominated by normal detritiation Tritium processing systems TRITIUM RECOVERY PRIMARY LOOP GENERATION SYSTEM SECONDARY LOOPS BLANKET reactor boundary PLASMA secondary confinement building confinement COOLANT PROCESS- ING AIR DETRITIATION tritium leak/permeation Water based heat transfer requires isotope separation.

12. Tritium is detectable far below the level that affects health. Impact pathway of tritium

13. Distance from the source(m) 1E-10 1E-8 1E-6 Effective dose equivalent (Sv/g) 1E21E31E41E5 Collective dose( personSv) 1E-6 1E-4 1E-2 Dose caused by normal tritium release of 1g And total “detriment” 1E2 1E4 1E6 population Impact of radioactive emission Tritium released from the facility diffuses but not disappear. According to the LNT hypothesis by ICRP, detriment increases with distance. Normal release accumulates in the environment. Dose is negligible compared with natural radiation, but detectable in environment, foods and drinking water. Same thing happens with C-14 and worse.

14. Waste Disposal Issue

15. TRITIUM containing medium will be confined : expansion volume : He expansion pool : water (easy) : other liquids IN CASE OF SPILL, TRITIUM IS RECOVERED BEFORE GOING OUT TO THE NEXT BARRIER DETRITIATION SYSTEM BUILDING DETRITIATION SYSTEM DETRITIATION SYSTEM TURBINE GENERATOR HX Against accidental release, Pressurized Helium requies Huge vacuum volume to Keep sound confinment. Tritium confinement in acceident Accidental spill can be recovered with normal detritiation. Heat transfer media and pressure requires different confinement. volume

16. Fuel Supply Issue Availability and stability of fuel resource will be important. Deuterium:its own detritiation Initial tritium : other power plant or its own Lithium : cooling sea water Lithium6 : lithium metal production Carbon : liquified natural gas - reduction of carbon-14, i.e. removal of nitrogen and carbon-13 Synergetic isotope separation systems must be considered for fuel and material supply. 1101001000 Operation days -2 0 1 2 3 Tritium Inventory TBR large Li-6 burnout TBR control TBR insufficient TBR and plant inventory

17. 2050206020702080 Fusion introduction year 0 20 40 60 80 100 Share of fusion in 2100 (%) Possible share of fusion energy Early introduction is essential for fusion. (Market will be occupied) Construction speed may limit possible fusion share. Avoiding initial tritium constraints increases capability of fusion. Maximum Construction Speed Case Initial Tritium Constraint Limit

18. ○Deployment of fusion requires socio-economic consideration. ・ economy ・ passive safety in accidental scenarios ・ normal tritium emission ・ solid waste issues ・ fuel and material supply and control ○ Socio-economic features are strongly dependent on blanket ・ economy – high temperature, high efficiency, hydrogen ・ environment - low activation, short life of rad-waste ○Strategic consideration ・ generations of blanket concepts have different purposes. ・ Evolution of blanket in ITER and DEMO is essential. Conclusion