Case Study of Roadmap to Tokamak Demo Reactor in Japan

1. International WorkshopMFE Roadmapping in the ITER EraSeptember 7, 2011 Princeton, New Jersey, USA Case Study of Roadmap to Tokamak Demo Reactor in Japan Kunihiko OKANOJapanCentral Research Institute of Electric Power IndustryGraduate School of Frontier Sciences, The University of Tokyo,

2. A request to Fusion Energy Forum from MEXT (October 2007）MEXT: Ministry of Education, Culture, Sports, Science and Technology To show a roadmap to finish the preparation for commercial use of fusion,@ before the middle of this Century@ assuming Tokamak plants Members of the working group for roadmap study

3. This roadmap study was done in 2007-2008. The roadmap was submitted to the MEXT (Ministry of Education, Culture, Sports, Science and Technology), then they took note it. As this roadmap was not revised after that time, any recent changes in the ITER schedule have not been reflected in this roadmap. The revision of roadmap is in progress by the committee organized by the MEXT. Thursday, Perspectives III H.Yamada, “Current Status of Discussion on Roadmap of Fusion Energy Research and Development in Japan”.

4. Basic agreements of WG members -1 # Commercial use of fusion should be ready before the middle of this Century → The commissioning of Demo should be finished by ~2040, because we will need DEMO operation for over 10 years in order to demonstrate the reliability of fusion plant. # Steady state operation should be demonstrated.Output of commercial plants should be steady state. Then, a steady state plasma operation will be desirable.If not, a kind of energy storage is required for the commercial plants with additional cost. From a view point of the reliability as well.

5. Basic agreements of WG members -2 #Plasma in the commissioning phase @The commissioning phase will start with inductive current or hybrid mode. This means that a CS coil with a reasonable volt*sec is required for the DEMO design. The operation will shift toward full steady state with Q>20 gradually, during the several years in the commissioning phase.

6. Basic agreements of WG members -3 #Definition for “demonstration of electric power generation” @ Net electric output, in final stage of the commissioning @ Generator power in plant scale (>several hundred MWe) should be demonstrated. (Note: this is just a proposal by the roadmap working group). This definition is different from the strategy decided by AEC in 2005*, where “1000MWe net electric output, certain economical cost and ITER-likesize” have been required. *Report on National Policy of Future Nuclear Fusion Research and Development, Atomic Energy Commission Advisory Committee on Nuclear Fusion, 26 October 2005.

7. Basic agreements of WG members -4 #Assumption about ITER project @Assuming that the burning plasma of ITER will not be very different from our present knowledge, we carry forward the DEMO engineering design (EDA phase), before DT burning experiment in ITER (~2022). @After the ITER DT (Q>10) operation, we will immediately move to a construction process (i.e. the design for construction by manufacturers). #Strategy for blanket development by DEMO @Large test ports will be prepared for TBM of advanced concepts. New concept blankets can be developed throughout the Demo project to improve the reliability and efficiency. This is because blankets installed by the first day of DEMO operation should be very conservative one. 2027 in latest schedule

8. Method to build up the roadmap (1) Completion of breakdown list of works required toward the DEMO. The list should include whole R&D issues, required to construct the DEMO. Note: This list must not be “a list of the existent R&D issues”. It is very important to find issues or works indispensable for constructing the DEMO but missing in the existent R&D issues. We have surveyed the R&D issues carefully, and broken down over 1000 works. (2) Completion of the time table for each work and check of the correlations to build our roadmap.

9. The number of Issues 106 15 30 185 414 38 33 36 37 30 13 90 13 14 7 29 23 8 5 Total : 1127 issues

10. 185 Decision making for SC materials and Max field on coil. If we chose a new type of SC coils beyond the ITER design, a lot of issues will appear.

11. 414 Basic design will be based on the ITER-TBM proposed by Japan.We assume that it will be successful !!

12. Demo des., R&D, Simulation

14. BA & IFMIF Demo des., R&D, Simulation

15. Demo des., R&D, Simulation

16. Demo des., R&D, Simulation

20. Finding by the work breakdown study It has been pointed out that some issues are critical for DEMO while R&D project does not exist yet or is insufficient in Japan. The following issues are the examples. The R&D’s need starting in this decade. NOTE!: These are not the most important issues, but are missing or insufficient issues in previous program. (ex1) Mass production factory of 6-Li enriched litium Except for designs with liquid Li breeder/coolant or LiO2 seramics breeder, the enrichment of 6-Li is indispensable to achieve reasonable TBR (local TBR > 1.3). Requirement of 6-Li for DEMO will be ~100 ton for every set of blanket. No factory to provide such amount of 6-Li, at least, in Japan, (possibly in the world too? )

21. Finding by the working breakdown study Cont. (ex2) Procurement of initial tritium inventory Sufficient amount of tritium should be secured before the commissioning of DEMO. In order to decide to move to the DEMO construction phase, a reliable path or method for the procurement of this initial tritium should be shown. Our possible choices: 1) Tritium production by fission reactors in Japan (but nearly impossible)2) Purchase from elsewhere (Who will be able to sell it us?)3) DEMO operation starts with a beam-driven DD operation, and shifts gradually to D/T=50/50 operation. Our simulation has shown that full DT operation is attained within 6 months with continuous 100MW NB injection. (Cost of this electric power >> present T price) S. Konishi et al., J. Plasma and Fusion Research, Vol.76，No.12 (2000)p.1309.Y. Asaoka, S. Konishi et al., "Commissioning of a DT Fusion Reactor without External Supply of Tritium.", Proc. of The 18th IAEA Fusion Energy Conference, PDP-08, Sorrento, Italy, Oct. 2000.

22. Finding by the roadmap & Working breakdown study Cont. (ex3) Maintenance method The maintenance concept should be fixed before stating the demo engineering design, because the maintenance method changes the overall design of the DEMOs. Our choice is extended widely between a full sector removal (like ARIES-RS, SLIM-CS, CREST) and a small module replacement (like ITER).ITER maintenance concept may not be acceptable from a view point of TBR. Based on our roadmap, the time limit for our decision is ~2015.

23. Finding by the roadmap & Working breakdown study Cont. (ex4) Divertor with Demo-relevant armor If we want to test the new divertor in ITER, a high reliability will be required to install it in ITER. Therefore we should begin the R&D of the divertor with Demo-relevant armor as soon as possible. (ex5) Anti tritium-transit technology for water cooling pipes If we use a water cooled ferritic steel blanket, a large amount of tritium may transit to the secondary cooling loop from the primary. Development of anti-transit coating or 3rd water loop with heat exchanger will be required. The 3rd loop reduces the thermal efficiency.

24. Summary on our roadmap study @ Breakdown list of works which consists of over 1000 works for the DEMO construction, has been built. @ The time schedules and a lot of decision points are defined on the working list. @ The roadmap has been built based on the list of break down structure of works, and the break down schedules. @ It has been pointed out that some issues are critical for DEMO while R&D project does not exist or is insufficient. We should begin those R&D’s during the next decade. Some example issues have been shown. @ Investigation of the impact by the newest ITER schedule is in progress, but it has not be included in the present roadmap yet.