22.033 Final Design Presentation

1. 22.033 Final Design Presentation

2. Vasek Dostal Knut Gezelius Jack Horng John Koser Joe Palaia Eugene Shwageraus And Pete Yarsky With the Help of Kalina Galabova Nilchiani Roshanak Dr. Kadak

3. Outline • Mission plan • Space power system • Surface power system • Conclusions • Future Work 22.033, Mission to Mars Design Course

4. Mission Design Goals • Reduce costs • Minimize initial launch masses. • Make use of re-usable, scalable and evolvable systems. • Increase science yield • Increase surface stay times. • Provide power rich environments. • Leverage advantages of nuclear energy to achieve these goals. 22.033, Mission to Mars Design Course

5. Mission Plan Summary • Nuclear Powered Telecommunication Satellite in Mars orbit • Demo space reactor & Electric Propulsion system • Sample Return • Demo surface reactor & ISRU plant • Manned Exploration • 2 distinct transfer types • Cargo Missions • Crew Transfer Missions 22.033, Mission to Mars Design Course

6. Cargo Missions • Large cargo mass to transfer. • Efficient transfer desirable to reduce propellant mass. • Transit time not critical (1+ year ok). • Reusable Mars Transfer System (MTS) • Ideal application for Electric Propulsion technology. • High Isp (high efficiency) • Low thrust (long transit is tolerable) 22.033, Mission to Mars Design Course

7. Cargo Missions 22.033, Mission to Mars Design Course

8. Electric Propulsion Options Cargo missions Array of advanced Ion / Hall thrusters 22.033, Mission to Mars Design Course

9. Crew Transfer Missions • Fast transit required • Reduces crew exposure to zero-gravity & radiation. • Increases surface stay time. • Requires high thrust to achieve • Propulsion Options • VASIMR (only viable EP technology) • NTR (Nuclear Thermal Rocket) • Chemical Rocket 22.033, Mission to Mars Design Course

10. Crew Transfer Missions • 3 Reactor Systems • 3 VASIMR Engines • Hydrogen Fuel • Transfer Habitat 22.033, Mission to Mars Design Course

11. Variable Specific Impulse Magnetoplasma Rocket – VASIMR Electric Propulsion (Manned Mission) 10 MW of power 22.033, Mission to Mars Design Course

12. SpacePower System 22.033, Mission to Mars Design Course

13. Nuclear Space Power System • Ultra-compact high power density reactor • Fast Spectrum • Pu Fuel • Molten salt or Li coolant • High temperature, low pressure coolant • Good heat transport medium • Thermo Photo Voltaic (TPV) cells • High efficiency power conversion (up to 40%) • No moving parts 22.033, Mission to Mars Design Course

14. Space Power System Goals • Design for multiple round trips • three 180 day round trips at full power • Low mass <3 kg/kWe • Scalable • 200 kWe - Precursor • 4000 kWe - Manned • Simple and reliable • No moving parts 22.033, Mission to Mars Design Course

15. Reusable System Strategy • Cargo missions (Mars Transfer System) • 1 new tank of propellant per transfer • 1 new reactor core after 3 transfers • Crew transfer (VASIMR System) • 1 new tank of propellant per transfer • 3 new reactor cores after 3 transfers 22.033, Mission to Mars Design Course

16. Pu as a Fuel • Most reactive fuel in fast spectrum • Small core size and mass • Critical mass is independent of isotopic composition • Proliferation resistant Reactor Grade Pu can be used • Compact core • High leakage, allows ex-core control • Small shield • Widely available • Reduced cost (238Pu for Cassini mission was imported) 22.033, Mission to Mars Design Course

17. Molten Salt Fast Reactor: Reference Core Design Power 11 MWth Dimensions 202020cm Total mass 185 kg - (50 kg Pu) Reflector thickness 6 cm (Zr3Si2) Coolant - molten salt (NaF-ZrF4) - High Boiling Temp Fuel - Reactor Grade Pu carbide, honeycomb plates keff BOL = 1.1 Core lifetime 540 FPD 22.033, Mission to Mars Design Course

18. Honeycomb Fuel

19. MSFR Core Layout

20. MSFR Technology Challenges • Fuel performance (El-Genk et al. 1984) • Coated particle dispersed alternative fuel form • Fuel – Cladding – Coolant compatibility • Li as alternative to corrosive Molten Salt • High temperature structural materials 22.033, Mission to Mars Design Course

21. MSFR Technology Challenges (cont.) • Pu fuel environmental concerns • Water submersion accident • Launch in robust capsule 22.033, Mission to Mars Design Course

22. Space Power Conversion CycleReference Concept • Coolant transfers the heat from the core to the internal radiator • All power is radiated towards TPV collector • TEM self powered pumps circulate the molten salt coolant • TPV collectors generate DC from thermal radiation • Residual heat is radiated into outer space reactor shield pump External radiator TPV array Internal Radiator 22.033, Mission to Mars Design Course

23. TPV Technology Challenges • Relatively low operating temperature needed for high efficiency 22.033, Mission to Mars Design Course

24. TPV Technology Challenges: Potential Solutions • Deployable radiator • Liquid Droplet Radiator 22.033, Mission to Mars Design Course

25. MSFR Scalability 22.033, Mission to Mars Design Course

26. mR/hr Radiation Detector Ĵo = 8.752 x 1013 n/cm2 s W LiH W R a d i a t o r Shielding MSFR Neutron Attenuation: LiH Gamma Attenuation: W 22.033, Mission to Mars Design Course

27. Shield Design Issues • Structural Design • Radiation induced LiH expansion • Thermal Design • 6Li (n,) reaction • 7Li enrichment • Proximity to the reactor core • Operating in temperature range 600-650 K 22.033, Mission to Mars Design Course

28. Surface Power System 22.033, Mission to Mars Design Course

29. Surface Power System Goals • Sufficient power for all surface applications (i.e. ISRU, habitat etc.) Satisfy NASA DRM. ~200 kWe • Develop long lasting Mars surface infrastructure • Lifetime of 25 EFPY 22.033, Mission to Mars Design Course

30. Surface Nuclear Power System • Cooled by Martian atmosphere (CO2) • Insensitive to leaks or ingress • Shielded by Martian soil and rocks • Low mass • Hexagonal block type core • Slow thermal transient (large thermal inertia) • Epithermal spectrum • Slow reactivity transient • Low reactivity swing 22.033, Mission to Mars Design Course

31. CECR Core Design • Power 1 MWth • Dimensions L=160 cm, D=40 cm • 37 hexagonal blocks • Total mass 3800 kg • Reflector thickness 30 cm (BeO) • Coolant Martian atmosphere (CO2) • Fuel 20% enriched UO2 dispersed in BeO • keff BOL = 1.14 • Core lifetime >25 EFPY 22.033, Mission to Mars Design Course

32. CECR Core Layout Fuel Pins Control Drums

33. CECR Thermal Hydraulics (fix it) • System pressure 480 kPa • Core inlet temperature 486 C • Core outlet temperature 600 C • Core mass flow rate 7.47 kg/s • Channel diameter 30 mm • Block flat-to-flat 63 mm • Film temperature difference 2.5 C • Pressure drop 25 kPa 22.033, Mission to Mars Design Course

34. CECR CO2 Cooled Epithermal Conversion Reactor • Two Martian atmosphere Brayton cycle options investigated: • Open cycle - intake from and discharge to the atmosphere • Closed cycle - intake from the atmosphere through a Martian atmosphere storage tank • Pressurized CO2 from atmosphere cools the core • Open cycle - ~ 100 kPa • Closed cycle - ~500 kPA Both options are capable of achieving ~20% efficiency 22.033, Mission to Mars Design Course

35. 3 REACTOR GENERATOR 2 TURBINE COMPRESSOR 1 4 Exhaust Intake through filter CECR CO2 Cooled Epithermal Conversion Reactor CO2 storage tank OPEN CYCLE CLOSED CYCLE 22.033, Mission to Mars Design Course

36. CECR Power Conversion Cycle • Acceptable efficiency (20% achievable) • Open cycle • Simple • Requires pressure ratio of 18 • Closed cycle • heat rejection is the weakest point of the design • massive pre-cooler or a fan is required • precooler increases the overall mass of the system • fan reduces the efficiency to 20% • The design requires further optimization 22.033, Mission to Mars Design Course

37. Surface Reactor Shield Core Martian soil Place for shutters 22.033, Mission to Mars Design Course

38. Conclusions • Mission plan • Technology demonstration • Reliability assurance before people are committed • Long term, reusability strategy • Reduces recurring costs to future missions 22.033, Mission to Mars Design Course

39. MSFR Space Reactor Features: Very high temperature, low pressure Thermo Photo Voltaic energy conversion Potential for High efficiency Ultra compact core Fast spectrum, RG Pu fueled Potentially reduced shield mass Conclusions 22.033, Mission to Mars Design Course

40. Conclusions • CECR Surface Reactor Innovations • Epithermal spectrum • Slow kinetics (maintains large Λ and βeff) • Enhanced conversion • Compromise between advantages of fast and thermal systems • CO2 coolant • Local resource • Resistant to leaks or ingress • Martian soil shield 22.033, Mission to Mars Design Course

41. Future Work • Further Development of conceptual designs • Molten Salt Fast Reactor Space System • Fuel performance and materials compatibility issues with different coolants • TPV & Radiator Technology • Criticality with water submersion • CO2 Cooled Epithermal Converter • Further Open Cycle & Closed Cycle Investigation • Development of low pressure and high pressure ratio turbomachinery • Surface Reactor Heat Rejection • Reactor startup & remote control strategy • Mission & Systems Integration 22.033, Mission to Mars Design Course

42. This surface reactor concept has been adapted for use with the Mars Homestead Project. For More Information, see: www.MarsHome.org 22.033, Mission to Mars Design Course