Survey of Space Nuclear Power Options
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Transcript of Survey of Space Nuclear Power Options
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Survey of Space Nuclear Power Options
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Dr. Andrew KadakAnd Peter Yarsky
MIT12.11.03
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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)
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UHPDC Core Layout
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
Outline
•Power Conversion
–Thermophotovoltaics (st)
–Thermionics (st)
–Brayton Cycle (dy)
–Rankine Cycle (dy)
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
Thermophotovoltaics (TPV)
1. LM transfers the heat from the core to the internal radiator
2. All power is radiated towards TPV collector
3. TPV collectors generate DC from thermal radiation
4. Unconverted heat is dissipated via the external radiator
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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.
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
Conceptual Unit Cell
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
Argon Brayton Cycle
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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)
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
Results for 1200 K
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
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ComparisonsT(hot) T(rej) Work Efficiency
TIC 1 (low T) 1200 K 750 K 0.4 MW 12%2 (high T) 2200 K 750 K 0.9 MW 25%1 (high T) 2200 K 1200 K 2.5 MW 12%
Ar Brayton 1600 K 850 K 0.95 MW 20%Na Rankine low T 1200 K 1000 K 1.1 MW 11%
high T 1500 K 1300 K 3.4 MW 13%TPV (MSFR) 1400 K 900 K 4 MW 40% **
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
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)
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
BONUS SLIDES
•Slides in case we need clarification
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Dec 10th and 11th , 2003 MIT 22.033 / 22.902, Mission to Mars
Single Layer Concept1. LM flows through UHPDC2. LM heats the emitter3. Electrons flow towards
collector4. Collector is in direct
contact with external radiator
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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