November, 2008 Lunar Fission Surface Power Design - Relap5 Point Kinetics D. S. Lucas INL

Acknowledgements Jim Werner, INL Space Rx Lead Juan Carbajo, Lou Qualls ORNL Relap5 Model Dave Poston LANL MCNP Reactivity Coefficients, FRINK Rich Riemke, INL R5 Code Development Cliff Davis, INL R5 Code Development & Modeling

Discussion Brief Background Deliverables Model Responsibilities Why Modeling and Simulation LANL,SNL,ORNL,INL Models Reactor Kinetics Importance SQA Summary and Recommendations

Background Fast Reactor on Moon for Colony Solar – Not enough Power Rx KW Thermal 40 kW(e) Net Reactor Power 8 full-power years Meet allowable dose levels Meet launch loads Operate in lunar environment Minimum reactor module mass and launch envelope Meet safety and safeguards requirements Meet reliability requirements

Design Parameters Fast reactor (Cat II) NaK coolant Open lattice core configuration Stainless steel reactor structure (SS-316) UO2 fuel BeO axial reflectors, Be radial reflector B4C in Radial Reflector Shim for reactivity control Coolant T-in = K, T-out = K (Subject to Change)

Core & Reactor

Pre-Decisional Deliverables Concept Trade Study Pre-conceptual Design Conceptual Design System models and tools System reliability assessment Demonstration of key technology –Fuel (vendor needed to meet Phase B/C/D schedule) –EM pump –I&C –(drum / sliders – motors, bearings, sensors) –Others? Safety assurance (INSRP) strategy Design and fabrication of components for TDU

Responsibilities LANL Overall Core Design ORNL Controllers, Heat Exchangers INL E&M Pumps, Backup TDU Simulator & Kinetics Argonne East – SASYS Model SANDIA – Simulink TDU Simulator Need Modeling and Simulation to combine with zero power critical tests and non-nuclear full scale system tests

Stir1* Stir2* Rad1 (66 kWt) Stir3* Stir4* PI2 Rad2 PS3 PS4PS2 PS1 PI1 Pwr Cond & Cont PLR Bus (270Vdc) Solar Array (5 kWe) Battery (10 kWh) IHX2 IHX1 Rx (183 kWt) PP2PP1 FPS Schematic NaK Tin,pc=825K dT=30K H2O Tin,rad=413K dT=25K 100 m User Loads (40 kW) Commands Telemetry 4 x 12 kWe 400Vac * Each Stirling converter includes two linear alternators. Thot=791K Tcold=425K Trad=382K Tclad=860K Aux Loads (5 kW) NaK Tout,rx=850K dT=50K

ORNL Relap5 Model Juan Carbajo - Modeling and Analysis of a Lunar Space Reactor – ICAPP - 08

Sandia Simulink

LANL FRINK & INL R5 TDU/Simulator Model – Put Reactivity Coefficients in ORNL Model Reactor Core In Out Pzr VP EM Pmp Sec EM PumpNaK SHotSCold H2O Pmp H2O Rad

Reactivity Data LANL MCNP ran with different material temperatures Keff’s Computed Contributions from Fuel, Moderator, Clad, Shields Data to R5 Format, Additional Heat Structures for SS Liner, Be Reflector, B4C Shield All Shields to be done with R5 Envelope Model Feedback from R5 to Neutronics Important ORNL Steady State with Neutronics Pump Trip Case with/without Shield with Neutronics Pump Trip at 200 seconds Simulation on PC out to 600 seconds

Pre-Conceptual Results Pumps Trip – With and without Radial B4C Shield Secondary Pump Trip Primary Half Flow

Pump Flow – Both Transients

No Shield Rx Power - Core Temperature Pump Trip

Shield Pump Trip

Secondary Pump Trip Constant HT

Half Flow Primary Pump 2.1 Kg/sec

Mid Core T

Conclusions & Future Tasks Model - Testing Heat Structures, Core Kinetics Run Limited Transients Nestle- Explain? Attila – SW Model Check Rx Coefficients Independent Review & Document Kinetics Give to Sandia & ORNL Checking New Geometry Data SQA Plan – Transients Couple R5 to NASA Glenn Stirlings via Model Center