Development of a high frame rate, bright flash neutron imaging method for rapid, transient processes
Open Access
- Author:
- Lani, Chad
- Graduate Program:
- Nuclear Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 01, 2019
- Committee Members:
- Marek Flaska, Thesis Advisor/Co-Advisor
- Keywords:
- thermal neutron radiography
bright flash neutron imaging
high frame rate
rapid transient processes
TRIGA pulses - Abstract:
- The objective of this work was to design and assess a novel digital high-speed imaging system in conjunction with neutron pulses from the Penn State Breazeale Reactor (PSBR) called bright flashes. These pulses are tens of milliseconds long with a peak power up to 761.0 ± 12.44 MW. This technique is like x-ray imaging by being capable of imaging items that cannot be capture with visual imaging but separates itself because the contrast is not dependent on material density but rather hydrogen content. The imaging system is capable of acquiring images up to 4000 frames per second (fps) frame rates and is thus capable of capturing rapid transient processes without motion blur. The process used to test the bright flash neutron imaging technique was air-water two-phase flow contained in a bubbler. To determine and to put into context the capabilities of this bright flash imaging system, the data acquired from Penn State were compared to images that were taken by using a continuous neutron source, at the CG-1D beamline of the High Flux Isotope Reactor (HFIR) of Oak Ridge National Laboratory. Images acquired ranged from acquisition speeds of 60 fps to 4,000 fps. The images were evaluated based on calculating the signal-to-noise and the contrast-to-noise ratios to determine their quality. The quality for the bright flash images was on average four to five times greater than that of the HFIR images and was determined that at higher frame rates bright flash imaging is more beneficial. Bright flash imaging has a limit on the duration of the acquisition being limited to tens of milliseconds of the pulse duration, nevertheless this is no limitation for short, rapid transient processes. In conclusion, both imaging methods have applications for numerous scenarios, but for rapid transient processes and frame rates greater than 500 fps the bright flash imaging is a superior method.