Neutron Radiography Technique Research Articles

Bone structure investigation using X-ray and neutron radiography techniques

In this paper we report a study of the periodic variation of bone tissue humidity immediately after death using both neutron and X-ray radiography techniques. After death, bone tissue experiences sequential change over time. This change consists of organic and inorganic phase variations of the bone structure, as well as gradual reduction of the bone's water content. These variations are investigated by periodically imaging dead bone using X-ray and neutron radiography. Chemical separation techniques such as calcification and decalcification were used to separate the organic and inorganic phases of the bone. Comparison between X-ray and neutron radiographs of bone following phase separation can be potentially used to investigate the bone disease or to determine a cause of death. In our experiments, we use adult rat femur bones, and the interpretations of these results are presented based on our understanding of bone structure and images produced by neutron and X-ray photon interactions.

Recent advances in fast neutron radiography for cargo inspection

Fast neutron radiography techniques are attractive for screening cargo for contraband such as narcotics and explosives. Neutrons have the required penetration, they interact with matter in a manner complementary to X-rays and they can be used to determine elemental composition. Compared to neutron interrogation techniques that measure secondary radiation (neutron or gamma-rays), neutron radiography systems are much more efficient and rapid and they are much more amenable to imaging. However, for neutron techniques to be successfully applied to cargo screening, they must demonstrate significant advantages over well-established X-ray techniques. This paper reviews recent developments and applications of fast neutron radiography for cargo inspection. These developments include a fast neutron and gamma-ray radiography system that utilizes a 14 MeV neutron generator as well as fast neutron resonance radiography systems that use variable energy quasi-monoenergetic neutrons and pulsed broad energy neutron beams. These systems will be discussed and compared with particular emphasis on user requirements, sources, detector systems, imaging ability and performance.

Study of the water uptake and internal defects of jute‐reinforced polymer composites with a digital neutron radiography technique

AbstractThe water‐uptake behavior of jute fabric and its composites with polycarbonate and polypropylene was monitor by a digital neutron radiography technique. The thermal neutron radiography facility of neutron transmission radiography (NEUTRA) at spallation source (SINQ) of the Paul Scherrer Institute was used for this work. The internal defects, such as voids, cracks, and inhomogeneity, of the composites were studied. The water‐uptake behavior of the jute fiber was also studied with a digital neutron radiography technique. The natural jute fiber showed higher water absorption than the composites. No voids or inclusions in these composites were observed. Moreover, both the jute and polymer were uniformly distributed and well mixed with the polymer matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Comparative Study of Water Absorption Behavior in Biopol® and Jute-reinforced Biopol® Composite using Neutron Radiography Technique

Water absorption behavior of Biopol® and jute-reinforced Biopol composites has been studied by adopting the CCD camera based digital neutron radiography technique. The surface of jute is pretreated with 2-hydroxyethyl methacrylate (HEMA) before composite fabrication. From the analysis of neutron transmission profile measurement, a negligible amount of water absorption is observed in both Biopol® and its composite. It has also been observed that water absorption behavior in Biopol® is less than that in its composites.

Scattering correction algorithm for neutron radiography and tomography tested at facilities with different beam characteristics

A precise quantitative analysis with the neutron radiography technique of materials with a high-neutron scattering cross section, imaged at small distances from the detector, is impossible if the scattering contribution from the investigated material onto the detector is not eliminated in the right way. Samples with a high-neutron scattering cross section, e.g. hydrogenous materials such as water, cause a significant scattering component in their radiographs. Background scattering, spectral effects and detector characteristics are identified as additional causes for disturbances. A scattering correction algorithm based on Monte Carlo simulations has been developed and implemented to take these effects into account. The corrected radiographs can be used for a subsequent tomographic reconstruction. From the results one can obtain quantitative information, in order to detect e.g. inhomogeneity patterns within materials, or to measure differences of the mass thickness in these materials. Within an IAEA-CRP collaboration the algorithms have been tested for applicability on results obtained at the South African SANRAD facility at Necsa, the Swiss NEUTRA facilities at PSI as well as the German CONRAD facility at HMI, all with different initial neutron spectra. Results of a set of dedicated neutron radiography experiments are being reported.

Diffusion Coefficient Measurements in Lithium Ion Conductive Oxides by means of Neutron Radiography

Neutron radiography (NR) technique has been applied to the diffusion coefficien measurements of lithium ions in ion conductive solids using 7Li/6 Listable isotopes as tracer. In this article, we present the procedure of diffusion coefficient measurement by means of NR method, and reviewed the results of three types of lithium ion conductors, i.e. Li4/3Ti5/3O4, LISICON solid solutions, and perovskite-type lithium ion conductors, including analyses of diffusion mechanisms.

The effect of substituent distribution on the decay resistance of chemically modified wood

Fungal durability of chemically modified wood was investigated with respect to the macroscopic distribution of substituents. Sugi (Cryptomeria japonica D. Don) sapwood samples were treated with modifying chemicals, which involved acid anhydrides (benzoic and n-hexanoic anhydrides) and acid chlorides (benzoyl and n-hexanoyl chlorides), to prepare benzoylated and n-hexanoylated wood. Neutron radiography technique was applied to visualize and evaluate the distribution of the substituents in those modified wood samples. Results revealed that the reaction with acid chlorides led to the heterogeneous distribution, high content of the substituents near the cross sections but relatively low content inside, while the modification with acid anhydrides resulted in the almost homogeneous distribution. The effect of such different distribution on the decay resistance was estimated by using the brown-rot fungus Fomitopsis palustris. It was found that wood samples modified with benzoyl and n-hexanoyl anhydrides exhibited clearly higher resistance against the brown-rot decay than those modified with corresponding acid chlorides, indicating the homogeneous distribution of the substituents is more effective. These results demonstrate that the substituent distribution is one of the important factors for the decay resistance of chemically modified wood.

Diffusion coefficient measurements of La 2/3− xLi 3 xTiO 3 using neutron radiography

Lithium tracer diffusion experiments using neutron radiography (NR) technique were carried out on the perovskite-type structured lithium ion conductors La 2/3− x Li 3 x TiO 3 in the temperature range from 150 to 400 °C. Isotope ( 6Li) concentration profiles in the annealed samples consisting of 7Li were measured by NR, from which the tracer diffusion coefficients of lithium ions were calculated. Lower lithium concentration samples showed higher diffusion coefficients and vice versa, which was consistent with the assumption that the diffusion coefficient is proportional to the cation vacancy concentration. On the other hand, the activation energies of lithium ion diffusion grow larger with the lithium content. In addition, correlation factors were discussed comparing with the diffusion coefficients obtained from the conductivity data.

05/00778 Development of a non-destructive neutron radiography technique to measure the three-dimensional soot deposition profiles in diesel engine exhaust systems

05/00778 Development of a non-destructive neutron radiography technique to measure the three-dimensional soot deposition profiles in diesel engine exhaust systems

Measurement of the void fraction in a channel simulating the HANARO fuel assembly using neutron radiography

A test section simulating the HANARO fuel channel was constructed and the void fraction was measured by using the high-speed neutron radiography technique. The test was performed at a beam facility of HANARO called Ex-core Neutron-irradiation Facility (ENF). D 2O was used as the working liquid and air was used to simulate the void. The measurements were made at various combinations of the liquid flow and gas flow and the result were compared with the predictions of the existing correlations.

Observation of the two-phase flow patterns for a finned assembly using neutron radiography

A test section simulating the HANARO fuel channel was constructed and a two-phase flow pattern was examined. D 2O was used as the working liquid and air was used to simulate the vapor. The high-speed neutron radiography technique was applied for the test and it was performed at a beam facility of HANARO called ENF (Ex-core Neutron-irradiation Facility). The flow pattern was also investigated with the ultrasonic technique and the results were compared with those from the neutron radiography images.

Application of neutron imaging plate and neutron CT methods on nuclear fuels and materials

Advanced neutron radiography techniques such as the neutron imaging plate (NIP) and neutron computed tomography (NCT) methods have been investigated in the practicability for the postirradiation examination (PIE). In current works, an unirradiated fuel rod was examined by NIP and NCT methods in order to collect the fundamental data for applying these techniques to the PIE. A fuel rod used is composed of seven-enriched UO/sub 2/ and two-natural UO/sub 2/ pellets with controlled sizes and shape that are loaded into a Zircaloy tube. The neutron radiography tests were performed by NIP and NCT methods at the 2nd Thermal Neutron Radiography Facility (TNRF-2) in the Japan Research Reactor (JRR)-3. In the NIP image of the fuel rod, the difference in the size, shape, and enrichment between the UO/sub 2/ pellets is obviously recognized. In the case of NCT method, the images clearly show the detailed shape of the cross section in both enriched and natural pellets; and difference in the enrichment between those pellets is also observed. In addition, size difference between fuel parts of specifications and those in NCT images is evaluated.

Neutron-detected tomography of impurity-seeded superfluid helium.

We describe a neutron radiography technique that can be used to map the distribution of 3He impurities in liquid 4He, providing direct and quantitative access to underlying transport processes. Images reflecting finite normal- and superfluid-component 4He velocity fields are presented.

Measurements of liquid–metal two-phase flow by using neutron radiography and electrical conductivity probe

Neutron radiography and electrical four-sensor conductivity probe method were applied to measurement of liquid–metal two-phase flow. Visualization and measurements of nitrogen gas–molten lead bismuth two-phase flow were performed by using neutron radiography technique. Simultaneous measurements of void fraction by using high-frame-rate neutron radiography and four-sensor probe were also performed to observe the bubble–probe interaction. At the same experimental conditions, four-sensor probe was applied to the measurements of interfacial area concentration in radial direction. From the visualization of the two-phase flow, it turned out that cap bubbles or elongated slug bubbles were dominant at the superficial gas velocity of 1.1–38.3 cm/s and no stable Taylor bubbles were detected in this experiment. Measured radial void fraction profiles obtained by neutron radiography and electrical conductivity probe agreed well with each other. From these measurements, the measurement error and basic characteristics of gas–liquid–metal two-phase flow were clarified.

Development of a non-destructive neutron radiography technique to measure the three-dimensional soot deposition profiles in diesel engine exhaust systems

A technique was developed to non-destructively measure the three-dimensional soot deposition thickness profiles in diesel engine exhaust components using a digital neutron imaging technique. In this technique, the test component positioned on a rotating platform is exposed to a thermal neutron beam from a nuclear reactor and the flux transmitted through the test object is measured using a digital neutron imaging system. The thickness of the diesel soot is then determined by analyzing the attenuation of this neutron flux. The technique was applied here to an aluminum pipe that was fouled for approximately 12 h by diesel exhaust from a diesel generator. The analysis of the neutron images indicated that the average soot thickness in the fouled pipe decreased nonlinearly along the pipe. It was also found that the measurements using this technique were within 16% of the direct destructive measurements of the thickness determined after sectioning the pipe.

Velocity field measurement in gas–liquid metal two-phase flow with use of PIV and neutron radiography techniques

To establish reasonable safety concepts for the realization of commercial liquid-metal fast breeder reactors, it is indispensable to demonstrate that the release of excessive energy due to re-criticality of molten core could be prevented even if a severe core damage accident took place. Two-phase flow due to the boiling of fuel-steel mixture in the molten core pool has a larger liquid-to-gas density ratio and higher surface tension in comparison with those of ordinary two-phase flows such as air–water flow. In this study, to investigate the effect of the recirculation flow on the bubble behavior, visualization and measurement of nitrogen gas-molten lead bismuth in a rectangular tank was performed by using neutron radiography and particle image velocimetry techniques. Measured flow parameters include flow regime, two-dimensional void distribution, and liquid velocity field in the tank. The present technique is applicable to the measurement of velocity fields and void fraction, and the basic characteristics of gas–liquid metal two-phase mixture were clarified.

Recognition of internal structure of unknown objects with simultaneous neutron and gamma radiography

Generally speaking in customary industrial and medical radiography, there is no tendency to reveal the nature of the samples. Ordinarily, the main objective of taking a radiograph is to show the position and dimension of unknown parts, inside the test object and to determine cracks, defects, etc. Whereas in radiography many important factors such as material cross-sections and build-up factors are also involved. In this paper, by using both neutron and gamma radiography techniques, some mathematical relations were successfully generated, in order to calculate the neutron and gamma total macroscopic cross-sections of some unknown elements in the presence of the other elements. For this work, some test pieces were defined and made of lead, silver, copper, Nickel, tin, graphite and polyethylene. The neutron radiography facility at Tehran Research Reactor (TRR) was used as mixed neutron and gamma radiography source (Proceedings of the Second World Conference on Neutron Radiography, Paris, France, pp. 25–32). On testing of a correction of the above-mentioned generated relations, a new technique of simultaneous neutron and gamma radiography was also investigated.

Quantitative flow visualization of fluidized-bed heat exchanger by neutron radiography

Quantitative flow visualization of a gas–solid fluidized-bed installed vertical tube-bank has been successfully conducted using neutron radiography and image processing technique. The quantitative data of void fraction distribution as well as the fluctuation data are presented. The time-averaged void fraction is well correlated by the drift-flux model. The bubbles formed in the bed, rise along the vertical tubes and the observed bubble size is smaller than that in a free bubbling bed without tube-banks. The bubble diameter is well correlated by the modified Mori and Wen’s correlation taking into account the pitch of tube arrangement. The bubble rise velocity is also well correlated by applying the drift-flux model. These results are consistent for both bed materials of Geldart’s B- and A-particles, while the bubble size is significantly different between two kinds of particles.

Velocity field measurement in gas?liquid metal two-phase flow with use of PIV and neutron radiography techniques

To establish reasonable safety concepts for the realization of commercial liquid-metal fast breeder reactors, it is indispensable to demonstrate that the release of excessive energy due to re-criticality of molten core could be prevented even if a severe core damage accident took place. Two-phase flow due to the boiling of fuel-steel mixture in the molten core pool has a larger liquid-to-gas density ratio and higher surface tension in comparison with those of ordinary two-phase flows such as air–water flow. In this study, to investigate the effect of the recirculation flow on the bubble behavior, visualization and measurement of nitrogen gas-molten lead bismuth in a rectangular tank was performed by using neutron radiography and particle image velocimetry techniques. Measured flow parameters include flow regime, two-dimensional void distribution, and liquid velocity field in the tank. The present technique is applicable to the measurement of velocity fields and void fraction, and the basic characteristics of gas–liquid metal two-phase mixture were clarified.

Recognition of internal structure of unknown objects with simultaneous neutron and gamma radiography

Generally speaking in customary industrial and medical radiography, there is no tendency to reveal the nature of the samples. Ordinarily, the main objective of taking a radiograph is to show the position and dimension of unknown parts, inside the test object and to determine cracks, defects, etc. Whereas in radiography many important factors such as material cross-sections and build-up factors are also involved. In this paper, by using both neutron and gamma radiography techniques, some mathematical relations were successfully generated, in order to calculate the neutron and gamma total macroscopic cross-sections of some unknown elements in the presence of the other elements. For this work, some test pieces were defined and made of lead, silver, copper, Nickel, tin, graphite and polyethylene. The neutron radiography facility at Tehran Research Reactor (TRR) was used as mixed neutron and gamma radiography source (Proceedings of the Second World Conference on Neutron Radiography, Paris, France, pp. 25–32). On testing of a correction of the above-mentioned generated relations, a new technique of simultaneous neutron and gamma radiography was also investigated.