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Three-Dimensional Thermal-Neutron Radiography

Description: Three-dimensional radiographic methods provide a means of determining the depth of defect indications and minimizing the confusion that results from overlapping images of structures at various depths in an object. One method of obtaining and displaying three-dimensional radiographic images is multiple-film laminagraphy, i.e., a series of radiographic films taken at different orientations can be viewed superimposed to present a sharply focused image of any desired object plane. Methods that use multiple-film laminagraphy for three-dimensional thermal-neutron images will be described.
Date: October 1976
Creator: Berger, H. & Reimann, K. I.
Partner: UNT Libraries Government Documents Department

Screening Mammography in Primary Care Settings: Implications for Cost Access and Quality

Description: This staff paper examines the implications for cost and quality, as well as for access to mammography, of expanding the supply of mammographic services in the primary care setting. The special issues raised by third-party businesses that package mammography services for primary care physicians are also discussed.
Date: October 1991
Creator: United States. Congress. Office of Technology Assessment.
Partner: UNT Libraries Government Documents Department

Monte Carlo modeling of neutron and gamma-ray imaging systems

Description: Detailed numerical prototypes are essential to design of efficient and cost-effective neutron and gamma-ray imaging systems. We have exploited the unique capabilities of an LLNL-developed radiation transport code (COG) to develop code modules capable of simulating the performance of neutron and gamma-ray imaging systems over a wide range of source energies. COG allows us to simulate complex, energy-, angle-, and time-dependent radiation sources, model 3-dimensional system geometries with ``real world`` complexity, specify detailed elemental and isotopic distributions and predict the responses of various types of imaging detectors with full Monte Carlo accuray. COG references detailed, evaluated nuclear interaction databases allowingusers to account for multiple scattering, energy straggling, and secondary particle production phenomena which may significantly effect the performance of an imaging system by may be difficult or even impossible to estimate using simple analytical models. This work presents examples illustrating the use of these routines in the analysis of industrial radiographic systems for thick target inspection, nonintrusive luggage and cargoscanning systems, and international treaty verification.
Date: April 1, 1996
Creator: Hall, J.
Partner: UNT Libraries Government Documents Department

Mobile X-ray imaging systems for the tank waste characterization project at the Hanford site

Description: Stored waste tank sampling of radioactive high-level nuclear waste is reilu ired for continued operations, waste characterization, and site safety. The Hanford site tank farms consist of 28 double- shell and 1.49 single-shell underground storage tanks. The ``full`` capacity of each of these tanks is approximately 1 million gallons. The waste stored in these tanks was generated as a result of defense materials production over the course of 4 decades. The single shell tanks are out-of-service and no longer receive liquid waste. Core samples of salt cake, liquid and sludge are remotely obtained using truck-mounted core drill platforms. Samples are recovered from the tanks through a 2.25-inch diameter drill pipe,, in segments contained in specially designed stainless steel samplers approximately 1.5-inch in outside diameter and 26-inches long. The sampled material in a given segment can include crystalline salt-cake, liquid, sludge and entrained gas. Drilling parameters will necessarily vary with different waste types, e.g., crystalline salt-cake versus sludge. At times, the core sample recovery has been marginal and inadequate for laboratory analysis needs. This necessitated a system to provide the drill-truck operators with ``real-time`` feedback about the physical condition of the sampled ``formation`` and the percent recovery, prior to receiving .,isual characterization information and nuclear assay measurements from the Hanford site 222-S Analytic!al laboratories, a process often requiring two week turn-around of data. This real- time information allows the drill-truck engineers to immediately vary the drilling parameters to maintain sample recovery.
Date: September 25, 1996
Creator: Weber, J.R.
Partner: UNT Libraries Government Documents Department

Synthesis of 2-D images from the Wigner distribution with applications to mammography and edge extraction

Description: A new method for the general application of quadratic spatial/spatial frequency domain filtering to imagery is presented in this dissertation. The major contribution of this research is the development of an original algorithm for approximating the inverse psuedo Wigner distribution through synthesis of an image in the spatial domain which approximates the result of filtering an original image in the DPWD domain.
Date: December 1995
Creator: Pettit, Elaine J. (Elaine Joyce)
Partner: UNT Libraries

Fast Neutron Effects on Du Pont 1290 Film

Description: Abstract: "Fast neutron effects on a widely used x-ray film have been investigated. The neutron flux was provided by the (d, t) reaction of a Cockcroft-Walton accelerator. Integrated exposures to 10-10 n/cm-2 were given the film. It was found that perturbations on film that were pre-exposed to Co-60 gamma rays from 10 to 2000 r were negligible. Simultaneous exposure of neutrons plus gammas also indicated negligible effect on the film insofar as the gamma dose was concerned."
Date: June 13, 1958
Creator: Block, Seymour & Hughes, Lewis
Partner: UNT Libraries Government Documents Department

End-to-End Radiographic Systems Simulation

Description: This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to develop a validated end-to-end radiographic model that could be applied to both x-rays and protons. The specific objectives were to link hydrodynamic, transport, and magneto-hydrodynamic simulation software for purposes of modeling radiographic systems. In addition, optimization and analysis algorithms were to be developed to validate physical models and optimize the design of radiographic facilities.
Date: July 23, 1999
Creator: Mathews, A.; Kwan, T.; Buescher, K.; Snell, C. & Adams, K.
Partner: UNT Libraries Government Documents Department

Health Technology Cast Study 34: The Cost Effectiveness of Digital Subtraction Angiography in the Diagnosis of Cerebrovascular Disease

Description: A case study by the Office of Technology Assessment (OTA) that presents "a careful description of the current and potential application of DSA (Digital Subtraction Angiography) within the area of diagnostic radiology concerned with cerebrovascular disease and to suggest the implications of the technology for patterns of clinical practice and patient care costs under different assumptions" (p. 3-4).
Date: May 1985
Creator: United States. Congress. Office of Technology Assessment.
Partner: UNT Libraries Government Documents Department

X-ray imaging of biological specimens

Description: I compared alternative techniques for x-ray imaging of biological specimens on the basis of (1) transverse and longitudinal resolution, (2) depth of field, (3) choice of recording medium, and (4) recording efficiency. For all imaging techniques, the dosages received by specimens were so high that the living state cannot be preserved, nor the structural integrity of the specimen be maintained in the usual sense.
Date: January 1, 1983
Creator: Solem, J.C.
Partner: UNT Libraries Government Documents Department

Design of a 7-MV Linear Transformer Driver (LTD) for down-hole flash x-ray radiography.

Description: Pulsed power driven flash x-ray radiography is a valuable diagnostic for subcritical experiments at the Nevada Test Site. The existing dual-axis Cygnus system produces images using a 2.25 MV electron beam diode to produce intense x-rays from a small source. Future hydrodynamic experiments will likely use objects with higher areal mass, requiring increased x-ray dose and higher voltages while maintaining small source spot size. A linear transformer driver (LTD) is a compact pulsed power technology with applications ranging from pulsed power flash x-ray radiography to high current Z-pinch accelerators. This report describes the design of a 7-MV dual-axis system that occupies the same lab space as the Cygnus accelerators. The work builds on a design proposed in a previous report [1]. This new design provides increased diode voltage from a lower impedance accelerator to improve coupling to low impedance diodes such as the self magnetic pinch (SMP) diode. The design also improves the predicted reliability by operating at a lower charge voltage and removing components that have proven vulnerable to failure. Simulations of the new design and experimental results of the 1-MV prototype are presented.
Date: September 1, 2008
Creator: Cordova, Steve Ray; Welch, Dale Robert (Voss Scientific, Albuquerque, NM); Oliver, Bryan Velten; Rose, David Vincent (Voss Scientific, Albuquerque, NM); Johnson, David Lee (L-3 Communications - Pulse Sciences, San Leandro, CA); Bruner, Nichelle Lee (Voss Scientific, Albuquerque, NM) et al.
Partner: UNT Libraries Government Documents Department

Fast neutron (14.5 MeV) radiography: a comparative study

Description: Fast neutron (14.5 MeV) radiography is a type of non-destructive analysis tool that offers its own benefits and drawbacks. Because cross-sections vary with energy, a different range of materials can be examined with fast neutrons than can be studied with thermal neutrons, epithermal neutrons, or x-rays. This paper details these differences through a comparative study of fast neutron radiography to the other types of radiography available. The most obvious difference among the different types of radiography is in the penetrability of the sources. Fast neutrons can probe much deeper and can therefore obtain details of the internals of thick objects. Good images have been obtained through as much as 15 cm of steel, 10 cm of water, and 15 cm of borated polyethylene. In addition, some objects were identifiable through as much as 25 cm of water or 30 cm of borated polyethylene. The most notable benefit of fast neutron radiography is in the types of materials that can be tested. Fast neutron radiography can view through materials that simply cannot be viewed by X rays, thermal neutrons, or epithermal neutrons due to the high cross-sections or linear attenuation coefficients involved. Cadmium was totally transparent to the fast neutron source. Fast neutron radiography is not without drawbacks. The most pronounced drawback has been in the quality of radiograph produced. The image resolution is only about 0.8 mm for a 1.25 cm thick object, whereas, other forms of radiography have much better resolution.
Date: July 1, 1996
Creator: Klann, R.T.
Partner: UNT Libraries Government Documents Department

RAYLEIGH-TAYLOR STRENGTH EXPERIMENTS OF THE PRESSURE-INDUCED alpha->epsilon->alpha' PHASE TRANSITION IN IRON

Description: We present here the first dynamic Rayleigh-Taylor (RT) strength measurement of a material undergoing solid-solid phase transition. Iron is quasi-isentropically driven across the pressure-induced bcc ({alpha}-Fe) {yields} hcp ({var_epsilon}-Fe) phase transition and the dynamic strength of the {alpha}, {var_epsilon} and reverted {alpha}{prime} phases have been determined via proton radiography of the resulting Rayleigh-Taylor unstable interface between the iron target and high-explosive products. Simultaneous velocimetry measurements of the iron free surface yield the phase transition dynamics and, in conjunction with detailed hydrodynamic simulations, allow for determination of the strength of the distinct phases of iron. Forward analysis of the experiment via hydrodynamic simulations reveals significant strength enhancement of the dynamically-generated {var_epsilon}-Fe and reverted {alpha}{prime}-Fe, comparable in magnitude to the strength of austenitic stainless steels.
Date: August 10, 2011
Creator: Belof, J L; Cavallo, R M; Olson, R T; King, R S; Gray, G T; Holtkamp, D B et al.
Partner: UNT Libraries Government Documents Department

LLNL flash x-ray radiography machine (FXR) double-pulse upgrade diagnostics

Description: When the FXR machine was first tuned on the 1980`s, a minimal amount of diagnostics was available and consisted mostly of power monitors. During the recent accelerator upgrade, additional beam diagnostics were added. The sensor upgrades included beam bugs (resistive wall beam motion sensors) and high-frequency B-dot. Even with this suite of measurement tools, tuning was difficult. For the current Double- Pulse Upgrade, beam transport is a more complex problem--the beam characteristics must be measured better. Streak and framing cameras, which measure beam size and motions, are being added. Characterization of the beam along the entire accelerator is expected and other techniques will be evaluated also. Each sensor has limitations and only provides a piece of the puzzle. Besides providing more beam data, the set of diagnostics used should be broad enough so results can be cross validated. Results will also be compared to theoretical calculations and computer models, and successes and difficulties will be reported.
Date: June 26, 1997
Creator: Ong, M.; Avalee, C.; Richardson, R. & Zentler, J.
Partner: UNT Libraries Government Documents Department

Recent Developments in Electronic Radiography

Description: An overview of the radiographic capabilities with emphasis on electronic image detection and processing at the Los Alamos National Laboratory is presented. Fixed facilities and portable x-ray sources and imaging systems make up the Los Alamos capability. Examples of imaging with large area amorphous silicon imaging panels, a portable computed tomography system, high speed x-ray imaging applications and equipment, and small area, high resolution imagers are given. Radiographic simulation and reverse engineering from radiographic images to computer aided design files and solid models is also presented.
Date: July 18, 1999
Creator: Fry, D.A.; Claytor, T.N.; Davis, A.W.; Jones, M.H.; Sheats, M.J.; Stupin, D.M. et al.
Partner: UNT Libraries Government Documents Department

Effects of Spatially Heterogeneous Porosity on Matrix-Diffusion as Investigated by X ray Absorption Imaging

Description: Laboratory experiments were performed to investigate the effects of spatial variation in porosity on matrix-diffusion processes. Four centimeter-scale slabs of Culebra dolomite taken from the Waste Isolation Pilot Plant site were used in the tests. Experiments involved the simple diffusion of iodine into a single edge of each rock slab while X ray absorption imaging was used to measure the resulting two-dmensional solute concentration field as a function of time. X ray imaging was also used to quantify the two-dimensional porosity field of each rock slab. Image analysis provided a unique opportunity to both visuake and quantifj the effects of the spatially variable porosi~ on matrixdMusion. Four key results were obtained. First, significant variation in rates of diffusion were realized over the relatively small length (centimeter) and time scales (months) investigated. Second, clear evidence of diffusion preferentially following zones of relatively higher porosity was noted. Third, rate of difhion was found to vary as tracer diffused into the rock slabs encountering changing porosity conditions. Fourth, strong correlation between porosi~ and the calculated diffusion coefficients was found. In fact, the nature of the correlation can be related to the geometry, position, and orientation of the heterogeneous porosity features populating each rock slab.
Date: October 20, 1998
Creator: Boney, C.; Christian-Frear, T.; Meigs, L. C. & Tidwell, V. C.
Partner: UNT Libraries Government Documents Department

Nondestructive-Evaluation Needs for Coal Liquefaction

Description: Nondestructive-evaluation (NDE) needs for coal liquefaction have been identified by acquiring information from site visits, a literature review, and discussions with government personnel. Nondestructive evaluation has been highly rated in importance as a way to help alleviate problems in coal-conversion systems. The primary problems are associated with highly erosive and corrosive slurries being transferred throughout the coal-conversion process. Applicable NDE techniques for both pre-service and in-service inspection include high-temperature ultrasonics, acoustic emission, radiography, acoustic holography, and ultrasonic spectroscopy.
Date: 1977?
Creator: Kupperman, D. S.
Partner: UNT Libraries Government Documents Department

A Statistical Study of EBR-II Fuel Elements Manufactured by the Cold Line at Argonne-West and by Atomics International

Description: Nine elements from each batch of fuel elements manufactured for the EBR-II reactor have been analyzed for uranium-235 content by NDA methods. These values, together with those of the manufacturer, are used to estimate the product variance and the variances of the two measuring methods. These variances are compared with the variances computed from the stipulations of the contract. A method is derived for resolving the several variances into their within-batch and between-batch components. Some of these variance components have also been estimated by independent and more familiar conventional methods for comparison.
Date: September 1977
Creator: Harkness, A. L.
Partner: UNT Libraries Government Documents Department

Autoradiographic Technique for Rapid Inventory of Plutonium-Containing Fast Critical Assembly Fuel

Description: A nondestructive autoradiographic technique is described which can provide a verification of the piece count and the plutonium content of plutonium-containing fuel elements. This technique uses the spontaneously emitted gamma rays from plutonium to form images of fuel elements on photographic film. Autoradiography has the advantage of providing an inventory verification without the opening of containers or the handling of fuel elements. Missing fuel elements, substitution of nonradioactive material, and substitution of elements of different size are detectable. Results are presented for fuel elements in various storage configurations and for fuel elements contained in a fast critical assembly.
Date: October 1977
Creator: Brumbach, S. B. & Perry, R. B.
Partner: UNT Libraries Government Documents Department