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Activities on reactor design for fast ignition

Activities on reactor design for fast ignition. T. Norimatsu, H. Azechi, Y. Kozaki, Y. Fujimoto, T. Jitsuno, T. Kanabe, R. Kodama, K. Kondo, N. Miyanaga, H. Nagatomo, M. Nakatsuka, H. Shiraga, K. A. Tanaka, K. Tsubakimoto, M. Yamanaka, R. Yasuhara, and Y. Izawa,

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Activities on reactor design for fast ignition

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  1. Activities on reactor design for fast ignition T. Norimatsu, H. Azechi, Y. Kozaki, Y. Fujimoto, T. Jitsuno, T. Kanabe, R. Kodama, K. Kondo, N. Miyanaga, H. Nagatomo, M. Nakatsuka, H. Shiraga, K. A. Tanaka, K. Tsubakimoto, M. Yamanaka, R. Yasuhara, and Y. Izawa, Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka 565-0871, Japan, E-mail; norimats@ile.osaka-u.ac.jp Presented at Japan-US workshop on Laser IFE March 21-23, 2005, GA. San Diego, USA

  2. Introduction IFE plant Design Committee Roadmap Chamber concept KOYO-F with a wet wall Protection scheme for the final optics Scenario for fuel loading and injection Summary Outline

  3. Chairman: K. Tomabechi Blue; from companyVice chairman: Y. Kozaki, T. Norimatsu Black; form university Supervisor groupK. Ueda, M. Nishikwam K. Okano, T. Yamanaka, A. Nosaka, Y. Ogawa, H. Kan, A. Koyama, T. Konishi, N. Tanaka, A. Sagara, Y. Hirooka, H. Nakazato, Y. Soman, H. Azechil K. Mima, S. Mori, Y. Nakao, N. Miyanaga, M. Nishikawa, K. Tanaka Plasma working groupH. Azechi, H. Shiraga, K. Mima, R. Kodama, Y. Nakao, H. Nagatomo, S. Ishiguro, T. Jozaki Laser working groupN. Miyanaga, Y. Suzuki, Y. Owadano, T. Jitsuno, M. Nakatsuka, H. Fujita, K. Yoshida, H. Nakano, T. Kanabe, H. Kubomura, Y. Fujimoto, T. Tsubakimoto, T. Kawashima, H. Furukawa, J. Nishimae Target working groupT. Norimatsu, A. Iwamoto, M. Nishikawa, M. Nakai, H. Yoshida, T. Endo System working groupY. Kozaki, K. Okano, A. Sagara, Kunugi, T. Konishi, H. Furukawa, M. Nishikawa, Y. Sakawa, Y. Ueda, K. Hayashi, Y. Soman, M. Nakai IFE plant design committee was organized under collaboration of ILE, Osaka and IFE Forum.

  4. rh rh < rc/4 rc rh < rc/4 rh ~ rc rc Fast ignition can reduce the required laser energy because of the smaller PV work. Fast heating needs petawatt laser. Critical issue is energy coupling.

  5. Assuming high energy electron range ; d = 0.6 g/cm2 Eh = 140{/(100g/cc)}-1.85 kJ Pb = 2.6{/(100g/cc)}-1.0 PW Ib = 2.4X1019 {/(100g/cc)}0.95 W/cm2 rb = 60{/(100g/cc)}-0.975m 150 Pure DT 10mg/cc Foam 100 Target Gain 30mg/cc Foam 50 0 40 60 80 100 [kJ] E dh Driver Energy for Core Heating, Actual energy and power of heating laser required for fast ignition after S. Atzeni, (Phy.Plasmas’99) EL= 60 - 100 kJ

  6. Roadmap toward laser fusion power plant by fast ignition

  7. Introduction Reactor Design Committee Roadmap Chamber concept KOYO-F with a wet wall Protection scheme for the final optics Scenario for fuel loading and injection Summary Outline

  8. Plant with 5 modular reactors Electric output power 1200 MW (250MW for laser) Laser 1100kJ+100kJRep-rate 4 Hz x 4Operation power 250 MW Target gain 160Blanket gain 1.15Thermal output power 770 MW/reactor Conversion efficiency 40 % Basic specification of KOYO-F with liquid wall

  9. Wet wall reactor for fast ignition scheme • KOYO-F has 1.1 MJ, 32 beams for compression, 100kJ heating laser and two target injectors. • Thermal out put 200 MJ/shotRep-rate 4 Hz • KOYO-F has vertically off-centered irradiation geometry to simplify the protection of ceiling.

  10. Layout of heating laser makes new issue. 30 compression beams + heating laser 32 compression beams + heating laser (1,0,0) (0,0,0) In the case of (0,0,0) layout, 80 % energy of neighboring 3 beams irradiates the cone. Power control is necessary.

  11. In the previous cascade reactor, chamber clearance would be the critical issue. Ten kg of LiPb will evaporate by a microexplosin. Top-open geometry will form an upward flow, which would make the clearance time longer.

  12. The first wall is pours metal plates that are saturated with liquid LiPb and are tilted to make a down flow after collisions at the center. Mixing of surface flow is necessary to reduce the vapor pressure before the next laser irradiation. Average gas pressure assuming pure laminar flow Y. Kozaki et al., IAEA, FEC

  13. To keep the surface wet, pours metal will be used. 400oC 0.8m3/s 400oC 2.1m3/s • Pours metal allows penetration of Liquid LiPb, resulting the surface is always kept wet.This scheme can save the electric power to circulate the heavy liquid LiPb.1MW for the surface flow0.3 MW for blanket. Vav=0.1m/s Average flow rate 0.1 m/s 0.2 m/s Vav=0.4m/s 1m 0.1m Ferrite 550oC 500oC dt=1.3 oC/shot dt=0.5 oC/shot

  14. Concept of cooling system 4 reactors For 1st wall 400℃ Electric power 1450MWe T -> E 41％ Blanket Blanket (LiPb) (LiPb) Steam generator Liquid wall 550℃ ,750MWt (LiPb) 8.38×10７kg/h (2.22m３/s) Electric output 1200MWe Generator Turbine Fusion yield(with blanket) 770MWt (870MWt) For laser and utilities 250MWe 400℃ Reactor (LiPb) 500℃ ,150MWt 3.1×10７kg/h (0.83m３/s) By Sohman JNC

  15. Introduction Reactor Design Committee Chamber concept KOYO-F with a wet wall Protection scheme for the final optics Scenario for fuel loading and injection Summary Outline

  16. Motion of ablated plume 140m/s Simulation result Initial condition for analytical model Reference H. Furukawa, Y. Kozaki, K. Yamamoto, T. Johzaki, and Kunioki Mima, 　　‘Simulation on Interactions of X-Ray and Charged Particles with First Wall for IFE Reactor ‘ Submitted to Fusion Engineering and Design (2004). P 1

  17. Saturation and Quenching of Pb plume in spherical isothermal expansion A saturation wave , and a quenching wave propagate from outside to the center. When the saturation wave passed by, condensation starts. (The temperature decreases.) When the quenching wave passed by, condensation ends. ( The density is too low) P 4

  18. Protection scheme of final optics by synchronized rotary shutters The rotational speed of the 1st disk is ~1000 rpm. 0.05Torr Xe or D2

  19. Simulation of liquid wall reactor started. LiPb in 2004

  20. No deposition of LiPb was observed on witness plate in 0.1 Torr H2.

  21. 0.5m 100m/s Pb vapor whose initial speed of 100 m/s can not reach final optics in 0.1 Torr buffer gas. Pb get into the duct at the rage of 5 mg/shot. -> 473 kg/year !! Cleaning is necessary.

  22. If evaporated vapors collide at the center and lose the momentum, the rep-rate would be limited. Offset irradiation would be the solution. In the case of LFE reactor, the fire position is not necessary at the chamber center.

  23. Introduction Reactor Design Committee Chamber concept KOYO-F with a wet wall Protection scheme for the final optics Scenario for fuel loading and injection Summary Outline

  24. Two or three injector will be used because it seems difficult to load fragile foam targets into the sabots at 4 Hz • Pneumatic acceleration with 80K He and fine adjustment by coils • V=300+/-1m/s2 Hz operation

  25. Model target • Foam insulated Solid DT with LiPb cone whose inner surface is parabolic • Shell Outer insulator 250mg/cc200mmGas barrier2mm Solid DT200mm • ConeLiPb0.5ｇ　Issue; Fabrication of cone with LiPb How to fill the fuel in short time?

  26. Thermal cavitation technique is the solution for fuel loading in batch process. • Thermal cavitation method can fill liquid fuel into foam layer without feed-back control. • Required condition is;Diameter of foam shell＞＞Vent port＞Feeder port＞＞Cell size of foam

  27. Demonstration of thermal cavitation with hemi foam shell • Liquid D2 was evacuated by a heater outside the pot.

  28. Step 1 Saturation of foam with liquid DT

  29. Step 2 Evacuation by laser heating

  30. Step 3 Finish

  31. Extra fuel (5.4%) will be loaded due to the meniscus formed between cone and shell. • Liquid fuel in outer meniscus will move to inside after stopping the laser irradiation. • There is another extra liquid in the meniscus formed between the cone and inner surface of the foam layer. • These extra fuel will compensate the shrinkage of hydrogen during freexing(15%)..

  32. Fuel loading system by thermal cavitation method. Tritium inventory 100g Not to scale

  33. When gun length is 10 m, residual gas pressure at the next injection is estimated to be 0.03 atm, which may disturb cryogenic layer. For simplification, the gas is initially stationary and pumping starts at both ends at t=0. Pevac pressure in tube at the next injection tevac time needs for evacuation Our estimation indicated that the pressure of residual gas at the next injection is 0.03 atm. Thermal load for cryogenic target? Needs differential pumping system This work is supported by Dr. T. Endo of Hiroshima Univ..

  34. Estimation of thermal load 1 60 cm 1.2 kW The size of revolver needs about 60 cm in the diameter • The thermal load due to propellant gas is ~1.2 kW. • Heat exchange rate with liquid He is ~ 0.1 W/cm2. • The diameter of revolver is estimated to be 60 cm, which makes hard to obtain high rep-rate. 4 Hz -> 2 Hz x 2

  35. Estimation of thermal load 2 66 kW 160 kW 280W to cool thermal radiation66 ×10=660 kW 470W to cool targets and egg plates 200kW 1 MW of electric power will be consumed to operate a pneumatic injector. to cool the revolver(280+470x2)×100=120 kW In total 980kW / injector

  36. Conceptual design of KOYO-F is continued basing on a wet wall. Critical issue of wet wall seems chamber clearance to achieve 4 Hz rep-rate. In a future laser fusion reactor, final optics at the end of 30m-long beam duct can be protected from metal vapor using a rotary shutter and 0.1 Torr hydrogen gas. The vapor (v=100m/s) will stop within 6m from the entrance of beam port. Fuel loading in mass production process will be carried out by thermal cavitation technique. Accuracy of fuel loading (goal, < 1%) is future issue. Summary

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