22.033 Mission to Mars Design Presentation

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22.033 Final Design Presentation
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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
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Our Vision

• Use nuclear technology to get people from Earth
  to Mars and back

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Outline

• Mission plan
• Decision methodology
• Space power system
• Surface power system
• Conclusions

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Mission Plan Summary

• Precursor 1
• Telecommunication nuclear powered satellite in
  Mars orbit
• Precursor 2
• ISRU and surface nuclear reactor demonstration /
  Sample Return
• Manned Missions
• Establish the infrastructure
• Send the people
• Bring them back

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Mars Nuclear Telecom Satellite

• Primary Objectives
• Validate space reactor system
• Validate nuclear electric propulsion system
• Provide high data rate communications.
• Increases science yield. In space, power is
  knowledge.
• Secondary Objectives
• Orbital video and hi-res pictures.
• High power Mars orbit experiments
• (active radar, etc.)

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ISRU Surface Reactor Demo / Sample Return

• Primary Objectives
• Validate Mars surface reactor technology
• Validate Mars surface ISRU
• Secondary Objectives
• Produce fuel for sample return
• Return Martian rocks to Earth

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Mars Infrastructure

• Launch Window 1
• Launch 2 Nuclear Powered Transfer Systems
• Launch first Earth Return Vehicle
• Launch first set of surface Infrastructure
• ERV waits in Mars Orbit
• Reactor deployed, ascent stage fueling begins
• Transfer Systems return to Earth for reuse

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Manned Exploration

• Launch Window 2
• Refuel all 3 Transfer Systems (sitting in LEO)
• Launch 2nd ERV Surface Infrastructure
• Launch Transit/Surface Hab
• Crew1 meet Hab in HEO
• Crew Lands near existing infrastructure
• Transfer Systems return to Earth for reuse

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Manned Exploration

• Launch Window 3
• Crew Meets ERV in Mars Orbit, return.
• More infrastructure sent to Mars.
• Second Crew Deployed.
• This Plan is similar to NASAs Design Reference
  Mission, but modified to take advantage of
  Nuclear Electric Propulsion.

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Electric Propulsion Options

• Precursor cargo missions
• Array of advanced Ion / Hall thrusters

Power 10 80 kW
Isp 3000 10000 sec
Thrust 1 3 N
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Electric Propulsion (Manned)

• Variable Specific Impulse Magnetoplasma Rocket
• VASIMR -

10 MW of power
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Space Power Goals

• Low mass
• lt3 kg/kWe
• Scalable
• 200-4000 kWe
• Simple and reliable
• No moving parts
• Multiple round trips

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Space Power Unit

• High temperature heat rejection
• Reduces the radiator size
• Thermo Photo Voltaic cells
• High efficiency power conversion (up to 40)
• No moving parts
• Molten salt coolant
• High temperature, low pressure coolant
• Good heat transport medium
• Ultra-compact high power density reactor

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ANDIE
Advanced Nuclear Design for Interplanetary Engine

1. Molten salt transfers the heat from the core to
   the radiator
2. All power is radiated towards TPV collector
3. TEM self powered pumps circulate the molten salt
   coolant
4. TPV collectors generate DC from thermal radiation
5. Residual heat is dissipated into outer space

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ANDIE Core Physics
Power 11 MWth Dimensions 20?20?20cm Total mass
185 kg Reflector thickness 6 cm (Zr3Si2) Coolant,
molten salt (5050 NaF-ZrF4) Fuel, RG Pu
carbide, honeycomb plates keff BOL 1.1 Core
lifetime 570 FPD
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Honeycomb Fuel
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ANDIE Core Layout
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ANDIE Thermal Hydraulics

• Fuel centerline temperature 1767K
• Core inlet temperature 1550K
• Core outlet temperature 1600K
• Core mass flow rate 249.81 kg/s
• Plate spacing 5.5 mm
• Plate thickness 2.05 mm
• Pressure drop 123 kPa
• Pumping power 11.89 kW (40 kWe)

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Internal Radiator

• Radiates 10MW towards TPV collectors
• TPV collectors generate 4 MWe (?40)
• Operates at 1575K temperature
• Annular U-tube design 39/35mm outer/inner
  diameter
• Made of titanium (w/ high emissivity coating)
• U-tube height 15 m
• Radiator weight 2967 kg
• Molten salt weight 1975 kg

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Pumps

• TEM pumps from SP-100 program
• Thermoelectric Electromagnetic Pump
• Self powered
• Self starting
• Self regulating
• No moving parts
• 10 year operating life
• Designed to operate at 1310-1350K
• Available operating experience

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Shielding ANDIE
Neutron Moderation and Absorption LiH Gamma
Attenuation W

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How much does ANDIE weigh?
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Surface Power Goals

• Sufficient power for all surface applications
• (i.e. ISRU, habitat etc.)
• 200 kWe

Objectives Weight
25 Years of Operation 29.4
Low Mass 17.6
Slow Transients 20.6
Low Reactivity Swing 8.8
Chemically Inert in CO2 23.5
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Surface Reactor Decision Problem

• 192 Possible Combinations
• Neutron Spectrum Thermal, Epithermal, Fast
• Coolant CO2, LBE
• Reactor Fuel UO2, UC, US, UN
• Matrix Material BeO, SiC, ZrO2, MgO
• Fuel Geometry Pin, Block
• 4 Decision Options Formulated
• Option 1 Epithermal, CO2, UO2, BeO, Block
• Option 2 Fast, CO2, US, SiC, Block
• Option 3 Fast, LBE, UC, Pin
• Option 4 Thermal, CO2, UO2, BeO, Block

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Multi-Attribute Utility Theory
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Option 1 Epithermal, CO2, UO2, BeO, Block Option
2 Fast, CO2, US, SiC, Block Option 3 Fast, LBE,
UC, Pin Option 4 Thermal, CO2, UO2, BeO, Block
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Surface Power System

• Cooled by Martian atmosphere (CO2)
• Insensitive to leaks
• 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

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CADEC
CO2 cooled Advanced Design for Epithermal
Converter

• Pressurized CO2 from atmosphere cools the core
• Direct, closed, recuperated Brayton cycle for
  electricity production (?net20)

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CADEC Core Physics

• Power 1 MWth
• Dimensions L160 cm, D40 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 gt25 EFPY

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What does CADEC look like?
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CADEC Thermal Hydraulics

• 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

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Shielding CADEC
Core
Martian soil
Place for shutters
Thickness (cm) 170 180 190 200 210
Corresponding dose rate, shield surface (mrem/hr) 75.5 31.7 13.3 5.6 2.4
Dose rate (GCR), Martian surface (mrem/hr) Dose rate (GCR), Martian surface (mrem/hr) Dose rate (GCR), Martian surface (mrem/hr) Dose rate (GCR), Martian surface (mrem/hr) Dose rate (GCR), Martian surface (mrem/hr) gt 1.1
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Conclusions

• Mission plan
• Technology demonstration
• Reliability assurance before people are committed
  
• Long term, reusability strategy
• Reduces recurring costs to future missions

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Conclusions

• ANDIE Innovations
• Molten salt coolant
• Very high temperature, low pressure
• Pre-rejection of heat at high temperature
• Small radiator mass
• TPV collector
• High efficiency conversion
• Ultra compact core
• Fast spectrum, RG PuC fueled
• Potentially reduced shield mass

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Conclusions

• CADEC Innovative features
• Epithermal spectrum
• Slow kinetics (maintains large ßeff)
• Enhanced conversion
• Compromise between advantages of fast and thermal
  systems
• CO2 coolant
• Local resource
• Resistant to leaks or ingress
• Martian soil shield

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Conclusions

• CADEC Brayton cycle
• Acceptable efficiency (25)
• Open cycle - operation is challenging
• Closed cycle - heat rejection is the weakest
  point of the design
• Massive pre-cooler required
• OR
• Required fan power is too high
• (reduces the efficiency to 20)
• The design requires further optimization

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Space Reactor Nuclear Design

• Goals
• Minimize reactor core mass and volume
• Provide 11 MW of thermal power for 3 ? 180 days
  round trips
• Flat reactivity throughout lifetime
• Controlled by out-of-core mechanisms

Options explored
Fast spectrum LWR Grade Pu Ultra-compact and
light Controlled by direct leakage Potential for
positive reactivity feedback

• Thermal spectrum Am242m
• Small fuel mass
• Requires moderator
• Challenging to control

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Space Reactor Thermal Core Moderator Mass
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Space Reactor Thermal Core kinf BOL
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CECR Description
Dimensions L 160 cm D core 40 cm D tot 100 cm
Hexagonal Pitch 12.6 cm 7 Blocks in Core 3800 kg Total Mass
Volume Fraction (core) 65 v/o Fuel/Matrix 5 v/o Structure 30 v/o Coolant
Control 25 v/o U238 Blanket 30 cm BeO Reflector 1 cm TaB2 Shutter
Fuel Form 30 v/o UO2 70 v/o BeO 20 enriched U BOL 10 Pu239 EOL
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Core Physics Unit Cell
Axial Leakage (unreflected) 6.5 Neutron streaming
Prompt Fission Time (L) 6 us Mirror BCs
Delayed Neutron Fraction (b) 0.0068 BOL 0.0054 after 40 MWD/kgHM
Reactivity Limited Burnup Keff 1.05 at 40 MWD/kgHM Reactivity Swing 0.13
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Core Physics Whole Core (HOM.)
TaB2 Control Drum Worth Total -0.409 Per Drum -0.0681 (-10 BOL)
Prompt Fission Lifetime (L) 700 us bL 5.1 us (BOL) SAFE 400 0.0035 us (BOL)
H2O Immersion 0.124 2 Designed to have negative feedback with CO2 on Mars