Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 3-2004 Isomer Energy Source for Space Propulsion Systems Benjamin L. Johnson Follow this and additional works at: https://scholar.afit.edu/etd Part of the Propulsion and Power Commons Recommended Citation Johnson, Benjamin L., "Isomer Energy Source for Space Propulsion Systems" (2004). Theses and Dissertations. 3937. https://scholar.afit.edu/etd/3937 This Thesis is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. ISOMER ENERGY SOURCE FOR SPACE PROPULSION SYSTEMS THESIS Benjamin L. Johnson, Captain, USAF AFIT/GA/ENY/04-M01 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. The views expressed in this thesis are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government. AFIT/GA/ENY/04-M01 ISOMER ENERGY SOURCE FOR SPACE PROPULSION SYSTEMS THESIS Presented to the Faculty Department of Aeronautics and Astronautics Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Master of Science in Astronautical Engineering Benjamin L. Johnson, BS Captain, USAF March 2004 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT/GA/ENY/04-M01 ISOMER ENERGY SOURCE FOR SPACE PROPULSION SYSTEMS Benjamin L. Johnson, BS Captain, USAF Approved: /Signed/ ____________________________________ Milton E. Franke (Chairman) date /Signed/ ____________________________________ Paul I. King (Member) date /Signed/ ____________________________________ Larry W. Burggraf (Member) date /Signed/ ____________________________________ Maximilian F. Platzer (Member) date AFIT/GA/ENY/04-M01 Abstract Presented in this work are the results of an investigation of alternative means for powering spacecraft and launch vehicles with energy sources other than chemical combustion. Nuclear Thermal Propulsion (NTR) and the energy release of a nuclear spin isomer present potential for increased rocket performance with a compact, high-energy fuel sources replacing the combustion engines of the Delta IV-H 1st and 2nd stage vehicles. NTR was represented by the Nuclear Engine for Rocket Vehicle Application, CERMET, and the Particle Bed Reactor (PBR) fission designs, while the isomer hafnium-178-m2 was investigated in a PBR configuration. Energy storage levels of 1.3 GJ/g are possible with this material, though the successful triggering and maintenance of a chain reaction in this material are still debated topics within the scientific community. The best application for either technology is as an upper stage vehicle with the shielding requirements reduced to that of just a shadow shield between the core and the spacecrafts upper structure. The fission designs are capable of specific impulse values between 800 and 1,000 s leading to mass savings in the range of 7,000 to nearly 10,000 kg once the engine masses and shielding have been included. An isomer core in the configuration of a 19-element PBR may be able to achieve a specific impulse on the order of 880 s with the isomer in metallic form, and specific impulse values as high as 1,090 s if the isomer is in the form of hafnium carbide. This translates to somewhere between a 5,000 and 9,000 kg depending on the material makeup of the core and heat efficiency. Payload mass increases by a factor of two or greater velocity change capability are the payoffs of these systems. iv AFIT/GA/ENY/04-M01 In loving memory of Joanne Johnson, 12/17/1949 to 8/27/2003 v Acknowledgments I would like to thank my advisor Dr. Milton Franke, the readers on my thesis committee; Dr. Burggraf, Dr. King, and Dr. Platzer, and my professors at AFIT for providing me with the tools needed to undertake this effort spanning a wide spectrum of scientific and engineering fields. Dr. Burggraf was especially helpful in providing last minute direction on some very important issues. I’d also like to thanks my sponsors from AFRL/PRAS for allowing me to work a research topic that I had great personnel interest in. Being a part of the ’04 class at AFIT was a benefit to my development and I thank my classmates and hope to work with many of them again in the near future. Benjamin L. Johnson vi Table of Contents Page Abstract .........................................................................................................................iv Acknowledgments ........................................................................................................vi List of Figures ...............................................................................................................x List of Tables ..............................................................................................................xi Nomenclature..............................................................................................................xiii 1. Introduction ...........................................................................................................1 1.1 Motivation.......................................................................................................1 1.2 Research Objective .........................................................................................3 1.3 Past Work........................................................................................................7 2. Background ..........................................................................................................10 2.1 Triggered Isomer Development ...................................................................10 2.2 Radioactive Decay.......................................................................................15 2.2.1 Forms of Radioactive Decay.............................................................15 2.2.2 Attenuation, Absorption, and Emission............................................19 2.2.3 Shielding and Reflecting...................................................................23 2.2.4 Environmental Laws and Regulations ..............................................25 2.3 Nuclear Rocket Development ......................................................................26 2.3.1 Types of Space Nuclear Reactors .....................................................26 2.3.2 Nuclear Engine for Rocket Vehicle Application (NERVA).............28 2.3.3 Particle Bed Reactor (PBR) ..............................................................30 2.3.4 CERMET ..........................................................................................30 2.3.5 Isotope Thermal Thrusters ................................................................31 3. Methods and Theory............................................................................................33 3.1 Assumptions.................................................................................................33 3.1.1 Isomer Decay Process .......................................................................33 3.1.2 Rocket Configuration........................................................................34 3.2 Nuclear Fission Reactor Performance .........................................................34 3.3 Rocket Fundamentals ...................................................................................35 3.3.1 Nozzle Analysis ................................................................................35 3.3.2 Conservation of Mass .......................................................................38 vii Page 3.3.3 Power Calculations ...........................................................................39 3.3.4 System Sizing....................................................................................40 3.3.5 Mission Feasibility............................................................................41 3.3.6 Rayleigh Line Analysis .....................................................................43 3.4 Hafnium Requirement..................................................................................44 3.5 Energy Deposition and Fluorescence...........................................................45 3.6 Radiation Shielding......................................................................................48 3.6.1 Nuclear Fission Shielding.................................................................49 3.6.2 Gamma-Ray Shielding......................................................................50 3.7 Individual Reactor Design ...........................................................................52 3.7.1 NERVA.............................................................................................53 3.7.2 CERMET ..........................................................................................54 3.7.3 Particle-Bed Reactor .........................................................................55 4. Results..................................................................................................................60 4.1 Propellants....................................................................................................60 4.2 Analysis of Stage 1 ......................................................................................62