Progress Report 2 Decisions and ModelsOverview – ScheduleCORECore - Current StatusCore - ScheduleCore - Schedule Post Nov. 3rdPCUPCU – Current StatusPCU – Decision MethodologyPCU - ScheduleRadiatorRadiator – Current StatusRadiator - ScheduleShieldingShielding – Current StatusShielding – ScheduleLSR Group Expanding Frontiers with Nuclear Technology The EndNuclear Engineering DepartmentMassachusetts Institute of Technology Lunar Surface Reactor Group Progress Report 2Decisions and ModelsLunar Surface Reactor GroupOctober 25, 2004LSR Group, 10/25/2004Slide 2Nuclear Engineering DepartmentMassachusetts Institute of Technology 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.LSR Group, 10/25/2004Slide 3Nuclear Engineering DepartmentMassachusetts Institute of Technology CORELSR Group, 10/25/2004Slide 4Nuclear Engineering DepartmentMassachusetts Institute of Technology 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 geometryLSR Group, 10/25/2004Slide 5Nuclear Engineering DepartmentMassachusetts Institute of Technology Core - ScheduleMemo - Method of Reflection 27-OctMemo - Structural Materials 28-OctDeliver - Bounds for Geometry (Shielding) 1-NovMemo - Bounds for Geometry (mass) 1-NovDeliver - Core Thermo-hydraulics (PCU) 1-NovMemo - Control Mechanisms 3-NovMemo - Core Thermo-hydraulics 3-NovMemo - Preliminary Model 3-NovLSR Group, 10/25/2004Slide 6Nuclear Engineering DepartmentMassachusetts Institute of Technology Core - Schedule Post Nov. 3rd•Accident analysis–Launch accidents–Feedback coefficients–Power transients•Spatial Model•ReportLSR Group, 10/25/2004Slide 7Nuclear Engineering DepartmentMassachusetts Institute of Technology PCULSR Group, 10/25/2004Slide 8Nuclear Engineering DepartmentMassachusetts Institute of Technology 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 verificationLSR Group, 10/25/2004Slide 9Nuclear Engineering DepartmentMassachusetts Institute of Technology PCU – Decision Methodology Brayton Sterling ThermionicsSmall Mass and Size (Cost) - 1.35Actual PCU 2 1 3Outlet Temperature 3 3 3Peripheral Systems (i.e. Heat Exchangers, A to D converter) 1 1 1Launchable/Accident Safe - 1.13Robust to forces of launch 1 2 3Fits in rocket 3 3 3Controllable - 1.14 2 2 2High Reliability and Limited Maintenance - 1.00Moving Parts 1 2 3Radiation Resistant 2 3 1Single Point Failure 1 2 3Proven System 2 2 2Inlet Temperature 3 3 1Total 23.77 26.55 28.51LSR Group, 10/25/2004Slide 10Nuclear Engineering DepartmentMassachusetts Institute of Technology PCU - ScheduleDeliverables:Memo - PCU OptionsMemo - PCU TypeDeliver - Output Temperatures Approximation, RadiatorDeliver - Preliminary Lunar Analysis of PCU, Radiator/ CoreMemo - Scaling OptionsMemo - Scalability Analysis for Mars (Radiator, Core) Memo - Detailed Design; Piping, Vessel, Materials (Lunar, Mars)Will meet Nov. 3Finished (1st Draft) Post Nov. 3LSR Group, 10/25/2004Slide 11Nuclear Engineering DepartmentMassachusetts Institute of Technology RadiatorLSR Group, 10/25/2004Slide 12Nuclear Engineering DepartmentMassachusetts Institute of Technology 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.LSR Group, 10/25/2004Slide 13Nuclear Engineering DepartmentMassachusetts Institute of Technology 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.LSR Group, 10/25/2004Slide 14Nuclear Engineering DepartmentMassachusetts Institute of Technology ShieldingLSR Group, 10/25/2004Slide 15Nuclear Engineering DepartmentMassachusetts Institute of Technology 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)LSR Group, 10/25/2004Slide 16Nuclear Engineering DepartmentMassachusetts Institute of Technology 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)LSR Group, 10/25/2004Slide 17Nuclear Engineering DepartmentMassachusetts Institute of Technology LSR GroupExpanding Frontiers with Nuclear TechnologyThe