Evaluation of the Experimental Set-up for Lead Zirconate Titanate Irradiation with Fission Fragments

Open Access
Author:
Wart, Megan Frances
Graduate Program:
Nuclear Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 10, 2017
Committee Members:
  • Marek Flaska, Thesis Advisor
Keywords:
  • radiation detection
  • fission fragment detection
  • piezoelectric materials
Abstract:
Piezoelectric materials convert mechanical to electrical energy, due to dipoles in their crystal structure. This characteristic may allow for piezoelectric materials to be used to detect radiation. As radiation bombards the material it stresses the crystalline structure and, if there is sufficient stress, an electrical signal will be produced. To determine if this proposed method of radiation detection would work, the threshold of radiation exposure required to create an electrical signal must be determined. To enable such experiments, an experimental set up must be designed and evaluated computationally for radiation safety and feasibility. This includes choosing a form of radiation and the source to provide it, as well as determining how the piezoelectric plates will be prepared. For these experiments, fission fragments will be used due to there relatively high mass, high energy, high specific ionization, and short range. To produce them, a highly enriched uranium foil will be irradiated with a neutron source. A frame was built to hold this foil securely against the samples of piezoelectric material. Lead zirconate titanate was chosen as the piezoelectric material to be tested since it is relatively inexpensive and commercially available. To determine the feasibility of the experiments and the appropriate source, the fission rate and fission fragment production were calculated using a Monte Carlo code for each of the two available sources: a plutonium beryllium source, and the thermal neutron beamline at the Breazeale reactor. Using the fission rate and the range a fission fragment of average mass, the flux of fission fragments entering the piezoelectric plates was calculated. Through this calculation it was shown that the thermal neutron beamline would provide the larger fission fragment flux to the samples. To maximize the fission fragment flux, in order to improve the chances of seeing an electrical signal, it was concluded that the thermal neutron beamline should be used. In the future, other types of radiation, such as alphas or neutrons will be tested. The piezoelectric material will also be optimized, by choosing a different compound, structure, or creating custom piezoelectric materials.