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Progress Report 2 Decisions and Models

Progress Report 2 Decisions and Models. Lunar Surface Reactor Group October 25, 2004. Overview – Schedule. Original schedule: November 3 rd completion date for all models and decisions. November 15 th finished. Except report Revised Schedule

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Progress Report 2 Decisions and Models

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  1. Progress Report 2Decisions and Models Lunar Surface Reactor Group October 25, 2004

  2. Overview – Schedule • Original schedule: • November 3rd completion date for all models and decisions. • November 15th finished. Except report • Revised Schedule • November 3rd completion date for all models and decisions. • Finish November 22nd.

  3. CORE

  4. Core - Current Status • Decisions made: • Zr3Si2 reflector material • Pin fuel elements • Decisions to be made this week: • Heat pipe coolant • Bounds of operating temperature • Bounds of geometry

  5. Core - Schedule

  6. Core - Schedule Post Nov. 3rd • Accident analysis • Launch accidents • Feedback coefficients • Power transients • Spatial Model • Report

  7. PCU

  8. PCU – Current Status • Decision: Thermionics • Inlet temperature 1800K • Outlet Temperature 950K • Progress • Thermionic model • inlet/outlet temperature vs. efficiency • Balance between decent radiator size and generated power • Heat Pipe model • Heat pipe configuration to ensure 100kWe at appropriate temperature • Issues to be resolved • Power Transmission • DC-to-AC conversion? • Heat Exchanger • ISRU • Needs • 1800K Core Temperature verification

  9. PCU – Decision Methodology

  10. PCU - Schedule Deliverables: Memo - PCU Options Memo - PCU Type Deliver - Output Temperatures Approximation, Radiator Deliver - Preliminary Lunar Analysis of PCU, Radiator/ Core Memo - Scaling Options Memo - Scalability Analysis for Mars (Radiator, Core) Memo - Detailed Design; Piping, Vessel, Materials (Lunar, Mars) Finished (1st Draft) Will meet Nov. 3 Post Nov. 3

  11. Radiator

  12. Radiator – Current Status • Research of thermal properties of lunar and Martian environments. • Programming of model for thermal calculations. • Tabulation of the thermal and mechanical properties of structural and functional materials. • Compilation of all potential radiator concepts.

  13. Radiator - Schedule • Application of mission-specific design restrictions to list of radiator concepts. Oct. 27th • Choice of materials and general structural design. Oct. 29th • Modeling of radiator concepts. Nov 3rd.

  14. Shielding

  15. Shielding – Current Status • Gamma and neutron spectrum still unknown so have the following contingencies: (UPDATE 10/24: first spectrum estimate available) • Neutron flux < ~7*105 neutrons/cm2•sec and thermal • Neglect neutron shielding because reactor dose is less than GCR dose • Neutron flux > ~7*105 neutrons/cm2•sec but thermal • Use boron-10 • Neutron flux > ~7*105 neutrons/cm2•sec but fast • Use neutron absorbing metal hydride (e.g. LiH, BH3) • Gamma shielding • Use lead unless neutron shield is too heavy • If neutron shield is too heavy, use cadmium for neutron and gamma attenuation • If neutron/gamma shield too heavy, use surface • (Moon: silicon oxides, Mars: iron oxides; both have similar macroscopic gamma interaction cross sections)

  16. Shielding – Schedule Choose geometry Ideally, use hemispheric shell If too heavy, use cylindrical shell and leave axial side unshielded If both too heavy, bury core If burying core is unfeasible for other engineering conditions, use cylindrical shell with “exclusion zone” Choose material based on above considerations in light of newly available spectrum After above decisions, perform analysis with core group for shield’s impact on reflection and leakage characteristics (may occur after 11/3)

  17. LSR GroupExpanding Frontiers with Nuclear TechnologyThe End

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