Matthew Walsh, 2015, Mechanical and Aerospace Engineering
This summer, I investigated the shielding requirements for a future small-scale fusion reactor, the PFRC-4, currently being developed by Samuel Cohen at PPPL. The reactor will burn Deuterium-Helium-3 with a power density of about one megawatt per meter of reactor length. It will serve as a propulsion system for space missions to other planets. The shielding needs to protect delicate components of the reactor, most importantly the superconducting coils, from neutron flux. Boron carbide was the material selected for shielding due to its large cross-section for neutron interactions. Using a particle simulation software, I simulated the operation of the reactor and used various configurations of shielding to find the minimum sufficient amount of shielding, which is important because mass will be a concern for space missions. Shielding thicknesses of less than 50cm were sufficient to give the superconductors a lifetime of 30 years or more, and with more shielding, it could even be safe for a human operator to be in the room during testing. I gained a lot of research experience through this internship, and I’m subsequently leaning heavily toward pursuing a graduate degree.