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Combinatorial Optimization of Scintillator Screens for Digital Neutron Imaging

Chuirazzi, William C
http://orcid.org/0000-0003-2193-0744
http://rave.ohiolink.edu/etdc/view?acc_num=osu1586903047809812

Abstract Details

2020, Doctor of Philosophy, Ohio State University, Nuclear Engineering.
Neutron radiography is a nondestructive method for imaging the internal condition of samples by measuring the neutron transmission through a sample. It provides contrast between certain sample materials in a complementary manner to other imaging techniques, such as X-rays radiography. Neutron radiography has been used for a wide variety of applications such as studying cultural heritage objects, fuel cells, nuclear fuels, and quality control of industrial products. Digital neutron imaging techniques have become more widely used by the neutron imaging community over the last two decades, enabling digital neutron tomography. Specialty applications, such as imaging highly radioactive fuels or using fast neutrons to image large or dense objects, are emerging in the field of digital neutron imaging. However, digital neutron imaging has several challenges that must be addressed to provide optimum performance. The scintillator screen, which produces a visible image under neutron exposure, must be improved to deliver images with higher spatial resolution in a shorter acquisition time. 6LiF and gadolinium oxysulfide (GOS) scintillator screens are currently the industry standard, but more study is needed to explore if other scintillator screen compositions can deliver improved performance in some applications. This work advances the state-of-the-art of digital neutron imaging by providing a combinatorial study on borated scintillator screens for thermal and epithermal neutron imaging applications. Converter material, scintillator thickness, scintillator particle size, converter-to-scintillator mix ratio, and substrate material are all parameters studied to determine their impact on digital image quality. High-resolution scintillator screens are also tested, and their underlying theory is explained. Boron-based scintillator screens were shown to have an increased neutron detection efficiency of 66% in a cold neutron beam when compared to 6LiF screens. The same screens exhibited a 300% improvement in detection efficiency of epithermal neutrons. Fast neutron imagers are also investigated as part of this effort. Plastic scintillator packaging and dopants are varied to determine which produce the best images. This study also focuses on distinguishing between a fast neutron signal and signals produced by gamma-rays. Finally, a new method for digitally imaging highly radioactive nuclear fuel is developed. Novel scintillator screens were characterized and optimized for this application. This digital transfer method neutron imaging is used to produce radiographs on fuel with a dose rate of 884 R/hr. Neutron tomography was also performed on irradiated nuclear fuel using a traditional method. These developments represent a significant advancement in the state of the art for neutron imaging scintillator technologies, providing significant benefit for the entire world-wide neutron imaging community.
Lei Cao (Advisor)
Aaron Craft (Committee Member)
Marat Khafizov (Committee Member)
Vaibhav Sinha (Committee Member)
Richard Vasques (Committee Member)
299 p.
Nuclear Engineering
Neutron; Radiography; Scintillator, Tomography; Imaging; Combinatorial; Boron; Dysprosium; Fast Neutron; Neutron Radiography; Neutron Scintillator Design; Neutron Scintillator

Recommended Citations

Citations

  • Chuirazzi, W. C. (2020). Combinatorial Optimization of Scintillator Screens for Digital Neutron Imaging [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586903047809812

    APA Style (7th edition)

  • Chuirazzi, William. Combinatorial Optimization of Scintillator Screens for Digital Neutron Imaging. 2020. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1586903047809812.

    MLA Style (8th edition)

  • Chuirazzi, William. "Combinatorial Optimization of Scintillator Screens for Digital Neutron Imaging." Doctoral dissertation, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586903047809812

    Chicago Manual of Style (17th edition)

osu1586903047809812
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This open access ETD is published by The Ohio State University and OhioLINK.