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Nuclear rocket propulsion
This document discusses nuclear thermal propulsion for space applications. It begins by introducing the concept and some historical programs in the US and Russia. It then discusses the benefits of nuclear thermal propulsion such as high efficiency and payload capacity compared to chemical rockets. The document goes on to describe three types of nuclear energy sources - fission, radioactive isotope decay, and fusion - that have been investigated for heating propellant. It provides details on nuclear fission and isotope decay rockets and components of a nuclear fission reactor before concluding with a comparison of advantages and disadvantages of nuclear rockets.
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Nuclear rocket propulsion
- 1. Suthan R Asst Professor Departmentof Aeronautical Engg NMIT-Bangalore
- 2. INTRODUCTION The applicationof nuclear energy to space propulsion systems has long been seen as a means to enable missions to outer space which are not achievable by any currently conceivable chemical-based propulsion system. During the latter half of the 20th century, nuclear rocket propulsion programs were initiated by the United States and Russia.To a large extent, these efforts were successful. however, for a variety of reasons these nuclear rocket programs were never carried forward to completion in spite of the fact that the test programs for these engines demonstrated efficiencies twice those of the bestchemical rocket engines
- 3. WHY NUCLEARTHERMAL PROPULSION INSPACE? Provide extreme power for future space mission Reduce fuel consumption and increases payload carrying capacity Higher propellant efficiency
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- 5. Three differenttypes of nuclear energy sources have been investigated for delivering heat to a working fluid, Usually liquid hydrogen, which subsequently can be expanded in a nozzle and thus accelerated to high ejection velocities (6000 to 10,000 m/sec). However, none can be considered fully developed today and none have flown.
- 6. They arethe fission reactor, the radioactive isotope decay source, and the fusion reactor. All three types are basically extensions of liquid propellant rocket engines. The heating of the gas is accomplished by energy derived from transformations within the nuclei of atoms. In chemical rockets the energy is obtained from within the propellants, but in nuclear rockets the power source is usually separate from the propellant
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- 8. In thenuclear fission reactor rocket, heat can be generated by the fission of uranium in the solid reactor material and subsequently transferred to the working fluid. The nuclear fission rocket is primarily a high- thrust engine (above 40,000 N) with specific impulse values up to 900sec. Fission rockets were designed and tested in the 1960s. Ground tests with hydrogen as a working fluid culminated in a thrust of 980,000 N (210,000 lb force) at a graphite core nuclear reactor level of 4100 MW with an equivalent altitude-specific impulse of 848 sec.
- 9. A hydrogentemperature of about 2500 K.There were concerns with the endurance of the materials at the high temperature (above 2600 K) and intense radiations, power level control, cooling a reactor after operation, moderating the highenergy neutrons, and designing lightweight radiation shields for a manned space vehicle. In recent years there have been renewed interest in nuclear fission rocket propulsion primarily for a potential manned planetary exploration mission. Studies have shown that the high specific impulse (estimated in some studies at 1100 sec) allows shorter interplanetary trip transfer times, smaller vehicles,
- 10. Radio active isotopedecay
- 11. In theisotope decay engine a radioactive material gives off radiation, which is readily converted into heat. Isotope decay sources have been used successfully for generating electrical power in space vehicles and some have been flown as a power supply for satellites and deep space probes. The released energy can be used to raise the temperature of a propulsive working fluid such as hydrogen or perhaps drive an electric propulsion system. It provides usually a lower thrust and lower temperature than the other types of nuclear rocket. As yet, isotope decay rocket engines have not been developed or flown.
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- 13. Fusion isthe third nuclear method of creating nuclear energy that can heat a working fluid.A number of different concepts have been studied. To date none have been tested and many concepts are not yet feasible or practical. Concerns about an accident with the inadvertent spreading of radioactive materials in the earth environment and the high cost of development programs
- 14. Comparison of LRE& NTRE
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- 16. Nuclear Reactor Nuclearreactors are assemblies containing sufficient fissionable material (uranium or plutonium) to produce a self-sustaining chain-fission reaction. The source of energy in such a system is the excess binding energy of the fissionable material compared with that of the fission products. The reaction is triggered by the absorption of a neutron by a fissionable atom.To be self-sustaining,an average of at least one of the neutrons released by a fissioning nucleus must be captured by another fissionable nucleus, producing a fission
- 17. Components Reflector: Reflects neutronsproduced in the reaction back into the core Prevents neutron leakage Maintains reaction balance Can be used to reduce the size of the reactor Typically made of Beryllium
- 18. Moderator Slows downneutrons in the reactor Typically made of low atomic mass material LiH, Graphite Fuel Element Contains the fissile fuel Usually Uranium or Plutonium Contains the propellant flow channels Control Rods Contains material that absorbs neutrons Decreases and controls neutron population and Controls reaction rate When fully inserted, they can shut down the reactor Configuration and placement is driven by the engine power level requirements
- 19. Advantages Disadvantages HighIsp (2-10x that of chemicalsystems) • Low Specific Mass (kg/kW) High Power Allows High Thrust HighT/W Reduced Radiation for Some missions Political Issues& Social Issues Low Technology Readiness Level(Maturity) Radiation issues (Shielding) High Inert Mass
- 20. TYPES OF NUCLEAR ROCKETS Solid Core NuclearThermal Rocket Gas Core NuclearThermal Rocket Liquid core NuclearThermal Rocket Nuclear Powered Electric Rocket Nuclear Pulse Rocket Nuclear Fission Fragment Rocket
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- 22. As liquidhydrogen moves through the channels, it is heated by the reactor into a high temperature gas, and then ejected from the exhaust nozzle of the rocket at high speeds. Liquid and gas core nuclear rockets operate according to a similar principle, but,instead of using a solid fuel core to heat the hydrogen propellant, they use a liquid or gaseous nuclear fuel, respectively
- 23. Gas core NTR Coreof NTR is in gaseous form. Uses gases fuel. Low molecular weight of fuel.
- 26. References Rocket propulsionelements by george p. sutton oscar biblarz (https://libgen.lc/ads.php?md5=8e5939c686fb51a881d35 4594c263252) Theory and Design Jet, Rocket, Nuclear, Ion and Electric Propulsion by Loh,W.H.T. (https://libgen.lc/ads.php?md5=0c9debe825a4da52043dd 7b53e6fbc91) Principles of Nuclear Rocket Propulsion by William J. Emrich Jr (https://libgen.lc/ads.php?md5=76688898aa219a83359b6 38d3edc3cb1)