Award Date


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical Engineering

First Committee Member

William Culbreth

Second Committee Member

Alexander Barzilov

Third Committee Member

Yi-Tung Chen

Fourth Committee Member

Georg Mauer

Fifth Committee Member

Monika Neda

Number of Pages



Nuclear thermal rocket propulsion has been proposed as a highly efficient technology for space vehicles traveling from earth orbit to the moon, Mars, and other locations in the solar system. With twice the performance of a chemical rocket, nuclear thermal propulsion (NTP) uses the thrust produced by heating hydrogen gas within a thermal nuclear reactor where the exhaust is then passed through a de Laval nozzle to produce supersonic flow. NTP engines were the subject ofthe NERVA experiments at the Nevada Test Site in the 1970’s, and they produced a specific impulse of up to 900 seconds which is almost twice the performance of the Saturn V rocket at 451 seconds. There are areas where nuclear thermal propulsion technology can be improved. To minimize corrosion within the reactor, different axial and radial neutron reflector geometries are recommended to minimize gradients in the neutron flux within the core resulting in smaller temperature gradients within the fuel. NTP also involves the use of hydrogen propellant at a lower mass flow rate to remove fission decay heat from the core to prevent melting of the fuel. Variable area rocket nozzles were studied to remove decay heat while providing significant thrust. This additional thrust was included in the calculation of the total impulse required during a burn of the rocket engine. Additionally, increases in the temperature of the hydrogen propellant in the reactor chamber translates to higher specific impulse. This could be achieved by using molten uranium carbide fuel and employing high temperature ceramics, including Ta4HfC5 and HfC. The temperature of the hydrogen propellant would increase from 2700 K for the NERVA engine to over 4000 K resulting in increased engine efficiency. Finally, an optimization program was written to determine whether the NERVA rocket design could be improved. The same program determined the optimal molten uranium carbide rocket design for space propulsion.


Compressible Flow; Differential Evolution Algorithm; Molten Uranium Reactor; Nuclear Thermal Propulsion; Optimization; Variable Area Nozzle


Aerospace Engineering | Mechanical Engineering | Nuclear Engineering

File Format


File Size

3700 KB

Degree Grantor

University of Nevada, Las Vegas




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