Date of Award
Master of Science in Engineering (MSE)
Mechanical and Aerospace Engineering
Jason T. Cassibry
Kunning G. Xu
Shielding (Radiation)--Simulation methods., Space vehicles--Shielding (Radiation)--Simulation methods., Monte Carlo method., Nuclear propulsion.
Pulsed fusion, fission and fission-fusion hybrid systems are currently being studied for advanced propulsion to enable rapid interplanetary space travel. A testbed for evaluating these technologies at the University of Alabama in Huntsville, called Charger-1, utilizes a form of Magneto-Inertial Fusion to implode small plasma loads with z-pinch that will produce thrust when coupled with a magnetic nozzle. Like all forms of nuclear propulsion, this experiment will also be able to produce significant amounts of ionizing radiation in the form of high energy neutrons and photons that need mitigation to protect personnel and equipment. The laboratory housing this testbed has existing shielding that is in need of verification to ensure safe operation; design standards for radiation protection use conservative approximations more than precision in their guidelines leading to large factors of safety in the final product. Used with a ground facility this is more than adequate, but for spaceflight applications more precision is needed to optimize shielding for maximum protection with minimum mass. The shielding for the laboratory is analyzed with Monte Carlo simulations in the MCNP radiation transport code. Techniques developed from this effort are then applied to a design concept for shielding a hypothetical spacecraft using pulsed fusion propulsion. Through the use of MCNP, the protected area of the Charger-1 facility is predicted to receive a worst case dose per pulse of 6.8×10^-8 Sieverts. This is 0.068% of the dose received from a single chest X-ray.
Hewitt, David Jason, "MCNP design of radiation shielding for pulsed fusion propulsion" (2020). Theses. 340.