A Basic LEGO Reactor
Design for the Provision of
Lunar Surface Power
John Darrell Bess
Nuclear Engineer/Reactor Physics

A...
2



Objective

 Develop a lunar nuclear reactor
 ¤ Modular, safe, and reliable
 ¤ Can be optimized for lunar-base
   powe...
3



Lunar Surface Power is Essential
 Sustained human and robotic presence
 ¤ Life-support systems
 ¤ Communications
 ¤ T...
4



Space Reactor Heritage
 U.S. has launched one SNAP-10A reactor
 Russia has launched over 30 space reactor systems
 Va...
5



A Basic Lunar Reactor




        Power Conversion
6



LEGO Reactor Design Features
 Lunar regolith            Failure of single
 functions as both         subunit does not...
7



Reactor Subunit Description - I
 5 kWe per subunit                 Drilled     SS-316
 25 kWt per subunit            ...
8



Reactor Subunit Description - II             Heat
                                            Transfer
 SS-316 monoli...
9



 LEGO Reactor Cluster
                        30 kWe system power
 Bulk        Regolith
                        Subun...
10


Mass Estimate for Unshielded Subunit
Mass (kg)                  Component                     Estimate Source
 207.16...
11



Specific Mass Comparison
    Space       Power   Unshielded   Specific Mass
   Reactor      (kWe)    Mass (kg)     (...
12



  Overall LEGO Reactor Design



                         Potassium Boiler
                              0.5 m


Ura...
13



Lunar Power Expansion
14



LEGO Reactor Evolution - I
 Fuels Development                  Axial Reflector/Shield
  ¤ Nitride Fuels             ...
15



LEGO Reactor Evolution - II
 Cladding Development   Waste-Heat Rejection
  ¤ Refractory Metals   ¤ High Temperature
...
16



Potential Applications
 Non-Lunar,             Irradiation Research
 Extraterrestrial       and Development
 Surface...
17



Conclusions
 A LEGO Reactor            Thermodynamic and
 cluster can provide the   heat transfer analysis
 30+ kWe ...
18



  Acknowledgments


Center for Excellence in
 Nuclear Technology,
   Engineering, and
       Research
19



Questions?
20



Extra Slides
Lunar Power Supply   21
22


Fast-Fission, Heatpipe-Cooled Reactor
 Fast-Fission                Heatpipe-Cooling
  ¤ Dense, compact cores     ¤ Hi...
23



Power Conversion
   Potassium Boiler                 Heatpipe Radiator
   Stirling Engine                  ¤ Redunda...
24



Concern for Launch Safety
  Subunit must remain          Current methods for
  subcritical (keff < 0.985)   maintain...
25



Launch Accident Analyses
   Accident Medium        MCNP5        MCNP5       MCNP5        KENO-VI
  (External / Inter...
26



Lunar Regolith Composition




      Engineering, Construction and Operations in Space IV,
   American Society of Ch...
27



Rock-Melt Drilling
 Also known as Subterrene
 or Subselene drilling
 High temperature
 application with heat pipes
 ...
28

Effects of Hexagonal Emplacement
                                  1.20



                                           ...
29



 Coupling Analysis
     Avery’s coupling coefficients
     Coefficients determined between all units in the
     hex...
30


Drafting Board   Launch Pad

                   Thorough
                   thermodynamic and
                   heat...
31
  Faring Limits                            Faring Limits

                    Launch Vehicles
<13.8-m H, <5-m D        ...
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LEGO Reactor - ICAPP 2008

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Modular reactor concept for the provision of power on the lunar surface.

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LEGO Reactor - ICAPP 2008

  1. 1. A Basic LEGO Reactor Design for the Provision of Lunar Surface Power John Darrell Bess Nuclear Engineer/Reactor Physics ANS Annual Meeting/ICAPP June 12, 2008 Research performed as part of the Center for Space Nuclear Research at INL
  2. 2. 2 Objective Develop a lunar nuclear reactor ¤ Modular, safe, and reliable ¤ Can be optimized for lunar-base power demand ¤ Implemented, and later evolved, using lunar-regolith* *lunar-regolith: “blanket rock”, the layer of loose, heterogeneous material scattered across the lunar surface
  3. 3. 3 Lunar Surface Power is Essential Sustained human and robotic presence ¤ Life-support systems ¤ Communications ¤ Transportation ¤ Scientific missions ¤ Development of innovative space technologies and knowledge ¤ Lunar colonization* and in situ resource mining and manufacturing *Eventual development of tourism, commercialization, and a lunar society ( )
  4. 4. 4 Space Reactor Heritage U.S. has launched one SNAP-10A reactor Russia has launched over 30 space reactor systems Various concepts have been proposed over the past 50 yrs ¤ Heatpipe Operated Mars/Moon Exploration Reactor (HOMER) ¤ Affordable Fission Surface Power System (AFSPS) ¤ Submersion Subcritical Safe Space (S^4) Reactor ¤ Space Power Annular Reactor System (SPARS) ¤ Space Nuclear Steam Electric Energy (SUSEE) ¤ Safe and Affordable Fission Engine (SAFE) ¤ Sectored Compact Reactor (SCoRe) ¤ Mars Surface Reactor (MSR) ¤ SP-100
  5. 5. 5 A Basic Lunar Reactor Power Conversion
  6. 6. 6 LEGO Reactor Design Features Lunar regolith Failure of single functions as both subunit does not cause shielding and reflector complete reactor failure material Versatility in placement Reactor subunits are of new reactor systems subcritical in design Potential for Lunar Decreased neutron evolution of design (in fluence = reduced situ) material damage Reduced thermal loads Modularity
  7. 7. 7 Reactor Subunit Description - I 5 kWe per subunit Drilled SS-316 25 kWt per subunit Hole Core UO2 fuel pellets (84 fuel pins) ¤ 93% U-235 ¤ 95% TD SS-316 cladding 43 Sodium heatpipes Lunar regolith shielding Lunar regolith reflectors Distributed core design Heatpipe Fuel Pin
  8. 8. 8 Reactor Subunit Description - II Heat Transfer SS-316 monolithic, and Power hexagonal core Conversion ¤ 2.94-cm (1.16”) pitch Systems ¤ 23.8-cm (9.37”) diameter core ¤ 1.64-cm (0.64”) diameter External holes Heatpipes 49-cm (19”) fueled height 106-cm (42”) heatpipe extension from core 170-cm (67”) primary subunit length Reactor Core Base Support
  9. 9. 9 LEGO Reactor Cluster 30 kWe system power Bulk Regolith Subunits placed 60-cm Regolith Melt apart Interstitial Control Rods ¤ nat-B4C ¤ 10-cm (4”) diameter ¤ 49-cm (19”) height ¤ SS-316 chamber Reactor Control Subunit Rod Unit
  10. 10. 10 Mass Estimate for Unshielded Subunit Mass (kg) Component Estimate Source 207.16 Reactor Core, Fuel, and Heatpipes MCNP5 10.15 Secondary Heat Transfer (Potassium Boiler) HOMER-25 35.71 Free-Piston Stirling Convertor 140 W/kg 29.07 Waste-Heat Rejection (Heatpipe Radiator) 688 W/kg 12.50 Power Management and Distribution HOMER-25 6.25 Cabling HOMER-25 72.53 Control Rod and Shaft MCNP5 373.37 Subtotal -- 74.67 20% Mass Contingency -- 448.04 Total without Shielding -- Each subunit contains 88 kg HEU. Maximum shielding mass would not increase total mass above ~1 metric ton.
  11. 11. 11 Specific Mass Comparison Space Power Unshielded Specific Mass Reactor (kWe) Mass (kg) (kg/kWe) HOMER-25 25 1564 62.6 LEGO Reactor 25 2240 89.6 Space Power Unshielded Specific Mass Reactor (kWe) Mass (kg) (kg/kWe) AFSPS 40 2916 72.9 LEGO Reactor 40 3584 89.6
  12. 12. 12 Overall LEGO Reactor Design Potassium Boiler 0.5 m Uranium Dioxide / Stainless Steel Core Hex-Conical 0.51 m Carbon-Carbon Composite Heat- pipe Radiators 6.45 m * 0.5 m D Free-Piston Stirling Space Converter 0.26 m Sodium / Stainless Overall Dimensions Steel Heatpipes 8.77 m High 1.06 m 0.50 m Diameter Stainless Steel Base Support 0.12 m * 0.24 m
  13. 13. 13 Lunar Power Expansion
  14. 14. 14 LEGO Reactor Evolution - I Fuels Development Axial Reflector/Shield ¤ Nitride Fuels ¤ Be or BeO ¤ Other Fissile Reactor Control Isotopes ¤ B4C Tri-Shades ‫ ﻬ‬Pu-239 ‫ ﻬ‬Th-232/U-233 ‫ ﻬ‬Cm-245/-244* ‫ ﻬ‬Am-242m* * Not Available in kg quantities
  15. 15. 15 LEGO Reactor Evolution - II Cladding Development Waste-Heat Rejection ¤ Refractory Metals ¤ High Temperature Coolant ‫ ﻬ‬Niobium ‫ ﻬ‬Lithium ‫ ﻬ‬Molybdenum- Rhenium ‫ ﻬ‬Inert Gases ‫ ﻬ‬Tantalum ¤ Liquid Droplet Radiators ¤ Oxide Dispersion Steels ¤ Regolith Heat Sink ¤ Tungsten-Cermet ¤ Thermophotovoltaics
  16. 16. 16 Potential Applications Non-Lunar, Irradiation Research Extraterrestrial and Development Surfaces ¤ Neutron Flux-Trap ¤ Mars, Mercury, ¤ Radioisotope Moons, Asteroids Breeding Symbiosis with Lunar ¤ Component Testing Manufacturing ¤ Regolith Analyses Thorium Breeding Terrestrial Develop of Modular Reactors for Rural and Developing Areas
  17. 17. 17 Conclusions A LEGO Reactor Thermodynamic and cluster can provide the heat transfer analysis 30+ kWe for a lunar will be necessary to base completely characterize the LEGO Reactor Means for waste-heat rejection may represent Further technological the limiting factor development may evolve the LEGO ¤ coupling distance reactor into a more ¤ maximum power competitive design Subunit mass of ~500kg
  18. 18. 18 Acknowledgments Center for Excellence in Nuclear Technology, Engineering, and Research
  19. 19. 19 Questions?
  20. 20. 20 Extra Slides
  21. 21. Lunar Power Supply 21
  22. 22. 22 Fast-Fission, Heatpipe-Cooled Reactor Fast-Fission Heatpipe-Cooling ¤ Dense, compact cores ¤ High heat transfer rate ¤ High fissile loading ‫ ﻬ‬Latent heat ¤ Liquid metal coolant ‫ ﻬ‬Faster than conduction ¤ Actinide transmutation ¤ Wick structure ¤ Deeper fuel burnup ¤ Heat source/sink ¤ Low corrosion ¤ Inherent stability ¤ Intrinsic safety ¤ Transient stability
  23. 23. 23 Power Conversion Potassium Boiler Heatpipe Radiator Stirling Engine ¤ Redundancy in design ¤ Optimal for ≤40 kWe ‫ ﻬ‬Fin failure ¤ Developing 5 kWe free- ‫ ﻬ‬Loop failure piston, space convertor ¤ Carbon “armor” for NASA Heater Displacer Alternator Head Drive Assembly Assembly Assembly
  24. 24. 24 Concern for Launch Safety Subunit must remain Current methods for subcritical (keff < 0.985) maintaining a subcritical reactor ¤ Prior to launch ¤ Poison control rods ¤ During launch or drums ¤ Upon accidental ¤ Removable beryllium impact reflectors ¤ When submerged ¤ Incorporated spectral in moderator and/or shift absorbers (Re, reflector material B4C, Gd2O3) ¤ When immersed ¤ Fuel reactor in-orbit in fire (or on the lunar ¤ i.e. Always surface)
  25. 25. 25 Launch Accident Analyses Accident Medium MCNP5 MCNP5 MCNP5 KENO-VI (External / Internal) (ENDL92) (ENDF/B-VI) (ENDF/B-VI) S(α,β)-VI Air / Air 0.6082 0.6040 -- 0.6040 Air / Sodium 0.6126 0.6075 -- 0.6085 Seawater / Sodium 0.8301 0.8197 0.8066 0.8081 Freshwater / Sodium 0.8482 0.8457 0.8250 0.8258 Sea Sand / Sodium 0.8885 0.8851 0.8747 0.8789 Dry Sand / Sodium 0.9020 0.8874 -- 0.8947 Fresh Sand / Sodium 0.9020 0.8935 0.8866 0.8925 Dry Sand / Dry Sand 0.9075 0.8971 -- 0.9070 Seawater / Seawater 0.9119 0.9029 0.8852 0.9297 Sea Sand / Sea Sand 0.9210 0.9106 0.9054 0.9286 Fresh Sand / Fresh Sand 0.9329 0.9257 0.9182 0.9380 Freshwater / Freshwater 0.9349 0.9226 0.9027 0.9457 Sea Sand / Seawater 0.9730 0.9621 0.9560 0.9953 Fresh Sand / Freshwater 0.9886 0.9717 0.9683 1.0067
  26. 26. 26 Lunar Regolith Composition Engineering, Construction and Operations in Space IV, American Society of Chemical Engineering, pp. 857-866, 1994.
  27. 27. 27 Rock-Melt Drilling Also known as Subterrene or Subselene drilling High temperature application with heat pipes to melt rock Melted material is forced into porous rock Results in a glassy finish with no debris 4-9 kWth power requirement
  28. 28. 28 Effects of Hexagonal Emplacement 1.20 Atmospheric Void Surrounding Core 1.15 Loose Regolith Filler Surrounding Core Effective Multiplication Factor 1.10 1.05 σk < 0.2% ∆kfill = 0.5 ± 0.2% 1.00 0.95 0.90 30 50 70 90 110 130 150 Centerline Distance Between Each Subunit (cm)
  29. 29. 29 Coupling Analysis Avery’s coupling coefficients Coefficients determined between all units in the hexagonal cluster ¤ Adjacent: kij = 0.1121±0.0025 ¤ 2-Away: kij = 0.1374±0.0026 ¤ Cross-Cluster: kij = 0.1411±0.0025 “Infinite” coupling: kij = 0.1496±0.0025 Reactor system is very loosely coupled Tightly coupled systems typically have kij values in the thousandths decimal place.
  30. 30. 30 Drafting Board Launch Pad Thorough thermodynamic and heat transfer analysis Ground testing Confirmation of final design for “flight” testing Safety and security measures
  31. 31. 31 Faring Limits Faring Limits Launch Vehicles <13.8-m H, <5-m D 10.5-m H, 7.5-m D Proposed (~20-21 mT) Current (~7-9 mT) ¤ NASA’s Exploration ¤ Delta IV Heavy System Architecture Study (ESAS) ¤ Atlas V Heavy Launch Vehicle (HLV)

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