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Title: Qualification and Stability of a Computed Tomography System for Small Parts Inspection

Authors:
 [1];  [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP) (NA-10)
OSTI Identifier:
1257124
Report Number(s):
LA-UR-16-24157
DOE Contract Number:
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: Digital Imaging 2016 ; 2016-07-25 - 2016-07-26 ; Mashantucket, Connecticut, United States
Country of Publication:
United States
Language:
English
Subject:
Digital Radiography, Computed Tomography

Citation Formats

Fry, David A., Lattimore, Brandon Michael, and Stull, Christopher Jason. Qualification and Stability of a Computed Tomography System for Small Parts Inspection. United States: N. p., 2016. Web.
Fry, David A., Lattimore, Brandon Michael, & Stull, Christopher Jason. Qualification and Stability of a Computed Tomography System for Small Parts Inspection. United States.
Fry, David A., Lattimore, Brandon Michael, and Stull, Christopher Jason. 2016. "Qualification and Stability of a Computed Tomography System for Small Parts Inspection". United States. doi:. https://www.osti.gov/servlets/purl/1257124.
@article{osti_1257124,
title = {Qualification and Stability of a Computed Tomography System for Small Parts Inspection},
author = {Fry, David A. and Lattimore, Brandon Michael and Stull, Christopher Jason},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 6
}

Conference:
Other availability
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  • We are building a tomographic x-ray scanner to inspect cast explosives and industrial parts and to study new materials. We will use the scanner to examine parts up to 38 cm, in height, 25 cm in diameter, and 25 kg in weight. We tested our reconstruction program by comparing the results of a computer experiment with the input data. The program can complete a 128-by-128 pixel reconstruction in about 10 minutes. The tomographic x-ray scanner rotates and translates the sample through a second-generation scan. We use a 32 -detector array with a 16-bit analog-to-digital converter purchased from Bio-Imaging Research. Themore » detector and source are mounted on optical tables; one is a base for the entire assembly, and the other supports the detector array. We use an x-ray source from IRT Corporation with an output of 2 mA at 320 kV. The source spot size is 0.8 mm and the output is stable to {plus minus}1% over 5 hours. 6 figs.« less
  • We have investigated three small explosive parts for the Pantex Plant in Amarillo, Texas using computed tomography (CT). A medium resolution, fan beam system was used to test imaging capabilities for small holes drilled into one of the parts, and to identify any inhomogeneities, cracks, voids, and inclusions if present in the other two parts. This system provides volumetric imaging. Its information is qualitative in that is allows us to see interior features but it cannot provide quantitative attenuation data. A second part of the investigation was to perform effective atomic number computed tomography on the parts using energy dispersivemore » spectroscopy methods. We wanted to experimentally identify the {open_quotes}average{close_quotes} chemical composition of the materials in the explosive and its shell and to detect any possible inhomogeneities in composition. A single beam, nuclear spectroscopy based system was used for this work. The radiation source was a silver anode x-ray tube. By measuring x-ray attenuation at specific energies (characteristic lines and narrow bands of continuum) we are able to quantitatively determine linear attenuation coefficients. By using ratios of such measurements, density cancels out and we effectively have ratios of mass attenuation coefficients. Through a look-up scheme of mass attenuation coefficients for different elements, we can determine the weighted average chemical composition, as averaged by x-ray attenuation. We call this averaged composition the effective atomic number ({open_quotes}Z{sub eff}{close_quotes}). We thereby obtain cross sectional images of a parameter related to the averaged chemistry of the object. Such images and the underlying data can reveal, for instance, segregation of explosive and binder.« less
  • The advantages of computed tomography using x-ray or gamma sources for the nondestructive testing of industrial materials, welded joints and equipment such as reactor components are discussed, and the successful use of the Los Alamos tomographic scanner is described. (LCL)
  • Computed Tomography (CT) using penetrating radiation (x- or gamma-rays) can be used in a number of aircraft applications. This technique results in 3D volumetric attenuation data that is related to density and effective atomic number. CT is a transmission scanning method that must allow complete access to both sides of the object under inspection; the radiation source and detection systems must surround the object. This normally precludes the inspection of some large or planar (large aspect ratio) parts of the aircraft. However, we are pursuing recent limited-data techniques using object model information to obtain useful data from the partial informationmore » acquired. As illustrative examples, we describe how CT was instrumental in the analysis of particular aircraft components. These include fuselage panels, single crystal turbine blades, and aluminumlithium composites. These tests were performed by the members of the Nondestructive Evaluation Section at the Lawrence Livermore National Laboratory (LLNL) where we have been actively working in CT research and development. The aerospace applications can represent various phases of the design, manufacture, assembly, test, and retirement of various components and assemblies.« less