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Survey of Space Nuclear Power Options

Survey of Space Nuclear Power Options. Dr. Andrew Kadak And Peter Yarsky MIT 12.11.03. Introduction.

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Survey of Space Nuclear Power Options

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  1. Survey of Space Nuclear Power Options

  2. Dr. Andrew Kadak And Peter Yarsky MIT 12.11.03

  3. Introduction The goal of current work at MIT is to identify potential Power Conversion Options with use of an Ultra High Power Density Core (UHPDC) that will be scalable to achieve requirements for a plethora of exploration missions, eventually meeting the needs for a manned mission to Mars MIT 22.033 / 22.902, Mission to Mars

  4. The MIT - UHPDC • Ultra High Power Density Core • Fast spectrum • Tightly coupled / leakage controlled • Reactor Grade Plutonium (PuC) • ~60% Pu239 / ~20% Pu240 • Honey Comb Fuel Nb cladding • 20 cm x 20 cm x 20 cm • 10 – 11 MWth (liquid metal) MIT 22.033 / 22.902, Mission to Mars

  5. UHPDC Core Layout

  6. Outline • Power Conversion • Thermophotovoltaics (st) • Thermionics (st) • Brayton Cycle (dy) • Rankine Cycle (dy) MIT 22.033 / 22.902, Mission to Mars

  7. Thermophotovoltaics (TPV) • LM transfers the heat from the core to the internal radiator • All power is radiated towards TPV collector • TPV collectors generate DC from thermal radiation • Unconverted heat is dissipated via the external radiator MIT 22.033 / 22.902, Mission to Mars

  8. TPV Challenges • TPV efficiency decreases with higher cell temperature • The temperature of external radiator is the coldest the TPV cells can be (900 K) • It is unlikely that TPV Power Conversion will be scalable. MIT 22.033 / 22.902, Mission to Mars

  9. Thermionic Converters (TIC) • TIC Benefits • Single or Dual Layered Concepts • Static and Direct • 12-15% efficiency for TH ~1200 K • 25% or higher efficiency for TH ~2200 K • Temperature of heat rejection is ~ 750 K • TIC Challenges • Direct Contact with the Fuel MIT 22.033 / 22.902, Mission to Mars

  10. Conceptual Unit Cell MIT 22.033 / 22.902, Mission to Mars

  11. TIC Comparison • Low Temperature Single • 1200 K emitter / 750 K collector • 12% efficiency / 400 kWe • High Temperature Dual • 2200 K emitter / 750 K collector • 25% efficiency / 900 kWe • High Temperature Single • 2200 K emitter / 1200 K collector • 12% efficiency / 2500 kWe MIT 22.033 / 22.902, Mission to Mars

  12. Argon Brayton Cycle MIT 22.033 / 22.902, Mission to Mars

  13. Low Med High T1 (low) 400 K 473 K 533 K T2 665 K 780 K 890 K T3 (high) 1200 K 1400 K 1600 K T4 830 K 970 K 1100 K Net Work 300 kW 560 kW 950 kW Efficiency 0.20 0.19 0.20 Mass Flow Rate 5.5 kg/s 9.1 kg/s 13 kg/s Reactor Power 1.5 MW 3.0 MW 4.9 MW Pressure Ratio 3.18 3.13 3.18 Comparisons MIT 22.033 / 22.902, Mission to Mars

  14. Sodium Rankine Cycle • Sodium because: • 2100 R (1167 K) saturation temperature at 15.4 psia (1.05 atm) • Neutronic Inertness • Heat Removal Properties (UHPDC) • Saturation Curves are steep (scalability) • Little Pumping Power Required • Phase Transition (maximal radiator usage) MIT 22.033 / 22.902, Mission to Mars

  15. Turbine Efficiency 0.95 0.9 0.85 Cycle Efficiency 11% 11% 11% Turbine Work [MW] 1.18 MW 1.15 MW 1.14 MW Turbine Outlet Pressure [psia] 4.0 3.7 3.2 Results for 1200 K MIT 22.033 / 22.902, Mission to Mars

  16. Comparisons

  17. Conclusions • Dynamic PCU technology is more effective and scalable than Static (Sodium Rankine in particular) • Static direct energy conversion is still attractive from a reliability standpoint (TIC in particular) MIT 22.033 / 22.902, Mission to Mars

  18. BONUS SLIDES • Slides in case we need clarification MIT 22.033 / 22.902, Mission to Mars

  19. Single Layer Concept • LM flows through UHPDC • LM heats the emitter • Electrons flow towards collector • Collector is in direct contact with external radiator MIT 22.033 / 22.902, Mission to Mars

  20. HEU alternative • Less Reactive Fuel • Larger Core • More Fuel Mass • More shielding Required • No Fertile-Fissile Species (240Pu) • Larger Reactivity Swing • More demand on Control Devices • Work Still in Progress on CBA MIT 22.033 / 22.902, Mission to Mars

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