Bimodal nuclear thermal rocket (BNTR) engines have been shown to reduce the weight of space vehicles to the Moon, Mars, and beyond by utilizing a common reactor for propulsion and power generation. These savings lead to reduced launch vehicle costs and/or increased mission safety and capability. Experimental work of the Rover/NERVA program demonstrated the feasibility of NTR systems…
Contents
1 Introduction
1.1 Nuclear Thermal Propulsion
1.1.1 Motivation
1.1.2 Operation
1.2 Bimodal Nuclear Thermal Rockets
1.3 Project Overview
1.3.1 Motivation
1.3.2 Objective
1.3.3 Approach
1.3.4 Primary Contribution
2 Previous Work
2.1 Nuclear Propulsion
2.1.1 Early Development: 1945-1955
2.1.2 Rover/NERVA-era: 1955-1973
2.1.2.1 Program Overview
2.1.2.2 Detailed Studies
2.1.2.3 Small Nuclear Rocket Engine
2.1.2.4 Summary
2.1.3 Space Exploration Initiative: 1989-1991
2.1.4 Modern NTR Developments
2.1.4.1 NERVA-Derived
2.1.4.2 Ceramic-Metallic (CERMET) Fuels
2.1.4.3 Oxygen Afterburning
2.2 Bimodal Operation
2.2.1 Historical Development
2.2.2 Post-SEI Studies
2.2.3 Design Reference Mission 4.0
2.2.4 Other Recent BNTR Studies
2.3 Reactor-Driven Brayton Cycle Power Systems
2.3.1 History
2.3.2 Prometheus Project: Recent Nuclear Brayton Cycle Develop-ment
2.3.2.1 CBC Work at Sandia
2.3.2.2 CBC Work at NASA Glenn
3 BNTR Engine System
3.1 Propulsion
3.1.1 Architecture
3.1.2 Theoretical Performance
3.1.3 NERVA-Derived Reactor Design
3.1.3.1 Overview
3.1.3.2 Pressure Vessel
3.1.3.3 Reflector
3.1.3.4 Control Drums
3.1.3.5 Fuel Elements
3.1.3.6 Tie Tubes
3.2 Power Generation
3.2.1 Ideal Brayton Cycle Analysis
3.2.2 Non-Ideal Brayton Cycle Analysis
4 Engine Modeling
4.1 Pre-Existing Codes and Models
4.1.1 Nuclear Engine System Simulation (NESS)
4.1.2 NPSS-Based Expander-Cycle NTR
4.1.3 Closed Cycle System Simulation (CCSS)
4.2 Numerical Propulsion System Simulation (NPSS)
4.3 New BNTR Model
4.3.1 Operation
4.3.2 Propulsion-Mode Model
4.3.2.1 Modifications to NESS-Based Model
4.3.2.2 Component Details
4.3.3 Power-Mode Model
4.3.3.1 Component Details
4.3.4 Power Mode Execution
5 Reactor Analysis
5.1 Overview
5.2 Fuel Elements
5.2.1 Propellant Thermodynamics
5.2.2 Propellant-Fuel Element Heat Transfer
5.2.3 Solution Method
5.3 Tie Tubes
5.3.1 Coolant Thermodynamics
5.3.2 Heat Transfer
5.3.3 Solution Method
6 Reference Engine Designs
6.1 Small Nuclear Rocket Engine (SNRE)
6.1.1 Design Point Details
6.1.2 Heat Deposition Data
6.2 Design Reference Mission 4.0
6.2.1 Propulsion Operation
6.2.1.1 DRM Case Study 1 – Propulsion
6.2.1.2 DRM Case Study 2
6.2.2 Power Generation
6.2.2.1 DRM Case Study 2 – Power
7 Results
7.1 Design Point Results
7.1.1 SNRE
7.1.1.1 Engine-Level Performance
7.1.1.2 Reactor Level Details
7.1.2 DRM Case Study 1
7.1.2.1 Engine-Level Performance
7.1.2.2 Reactor-Level Details
7.1.3 DRM Case Study 2
7.1.3.1 Propulsion Operation
7.1.3.2 Power Operation
7.1.4 Baseline BNTR Design
7.1.4.1 Propulsion Operation
7.1.4.2 Power Operation
7.1.4.3 Power Operation – Engine Out
7.2 Trade Studies
7.2.1 Propulsion Trade Studies
7.2.1.1 Chamber Temperature and Pressure
7.2.1.2 Reactor Length
7.2.1.3 Reactor Peak-to-Average Factor
7.2.2 Power Trade Studies
7.2.2.1 Reactor Size
7.2.2.2 Reactor Length
7.2.2.3 Compressor Inlet Pressure and Pressure Ratio
7.2.2.4 Compressor Inlet Temperature
7.2.2.5 Turbine Inlet Temperature
7.2.2.6 Design Output Power
7.3 Technology Limitations
7.3.1 Tie Tube Layer Gaps
7.3.2 Fuel Element Survivability
7.3.3 Radiator Design
8 Conclusions
8.1 Bimodal Feasibility….
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Source: University of Maryland