Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 1 CORE

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 2 Core - Design Concept Develop a 100 kWe reactor with a 5 full- power-year lifetime Evaluation of options were based on design criteria: –Low mass –Launchability –Safety –High Reliability

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 3 Core - Design Choices Fast Spectrum Ceramic Fuel – Uranium Nitride, 33.1 w / o enriched Tantalum Burnable Poison Lithium Heatpipe Coolant Fuel Pin Elements in tricusp configuration External Control By Drums Zr 3 Si 2 Reflector material TaB 2 Control material

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 4 Core - Design Specifications UN fuel and Ta poison were chosen for heat transfer, neutronics performance, and limited corrosion Heat pipes eliminate the need for pumps, have excellent heat transfer, and reduce system mass. Li working fluid operates at high temperatures necessary for power conversion unit: 1800 K

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 5 Heatpipe Fuel Pin Tricusp Material Core - Design Specifications (2) Fuel pins are the same size as the heat pipes and arranged in tricusp design.

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 6 Core - Design Specifications (3) Reflector controls neutron leakage Control drums add little mass to the system and offer high reliability due to few moving parts Radial Reflector Control Drum Reflector and Core Top-Down View Reflect or Core Fuel Pin Fuel Reflector Zr 3 Si 2 Reflector Total Mass: 2654kg 42 cm 88 cm 10 cm Reflector

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 7 Integration Insert picture of reactor design from Joe

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 8 Launch Accident Analysis Many accidents were considered however, only accidents upon launch could not be prevented by extra safeguards. Worst Case Scenarios: –Uniform dispersion of all U 235 in atmosphere –Undeformed core with all heat pipes ruptured lands in water or wet sand

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 9 Launch Accident Results Reflectors StowedReflectors Detached WaterK eff = ± K eff = ± Wet SandK eff = ± K eff = ± Total Dispersion of the 157 kg of U235 will increase the natural background radiation by % Water and Wet Sand Landing will not result in criticality

Nuclear Engineering Department Massachusetts Institute of Technology MSR Group, 11/14/2004 Slide 10 Future Work Investigate further the feasibility of plate fuel element design Optimize core configuration Examine long-term effects of high radiation environment on chosen materials Develop comprehensive safety analysis for launch accidents