Award Date

5-1-2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Committee Member

Alexander Barzilov

Second Committee Member

Yi-Tung Chen

Third Committee Member

William Culbreth

Fourth Committee Member

Woosoon Yim

Fifth Committee Member

Moses Karakouzian

Number of Pages

140

Abstract

Remote sensing of ionizing radiation has a significant role in waste management, nuclear material management and nonproliferation, radiation safety, and accident response in situations such as the Fukushima nuclear power plant accident. Robotic platforms are able to surpass the number of tasks that could be achieved by humans. With the use of robots, the operator’s radiation exposure can be considerably decreased. Remote sensing allows for the evaluation and monitoring of radiological contamination in hazardous and hard to reach areas and locating radiation sources. In this work, gamma-ray and neutron sensors were integrated onto the unmanned aerial systems (UAS) making it possible to assay the unsafe zones remotely. Radiation data were automatically processed onboard of the smart sensor (segregation of photon and neutron signatures, gamma spectra analysis) and fused with the GPS data. This approach allows for the radiation sensor data to be dynamically tracked and mapped thus enabling further analysis of the radiation flux in the time and space domains. Maximum likelihood estimation (MLE) technique was used to locate the position of the radiation source based on the signal intensities measured in three or more locations by a single UAS or simultaneously by multiple UAS. The probabilities to locate a source with an unknown yield in an assayed area were calculated. If the robotic platforms are exposed to ionizing radiation, radiation damage occurs in the electronics components, limiting the platform’s operational time. The estimation of radiation damage of the components is important in order to optimize the robot’s operational lifetime in contaminated zones. Displacement per atom (DPA) characterizes the displacement damage on materials incurred by the radiation, which affects the macroscopic crystal defects. DPA depicts how many times atoms have been displaced from their lattice sites, representing the damage-based exposure unit. The FLUKA and SRIM/TRIM codes were used to analyze the DPA and ions transport processes in components of UAS and ground platforms. Packaging and the shielding designs were determined so that the operational time of the robot is increased.

Keywords

Computation Modeling; Radiation Damage; Radiation Detectors; Remote Sensing; Robotic Platforms; Source Search Methods

Disciplines

Mechanical Engineering | Nuclear Engineering

File Format

pdf

File Size

11.1 MB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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