The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform
Hirotaka Furuya - One of the best experts on this subject based on the ideXlab platform.
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upgrading of x ray ct technology for analyses of irradiated fbr mox fuel
Journal of Nuclear Science and Technology, 2012Co-Authors: Akihiro Ishimi, Koji Maeda, Kozo Katsuyama, Tsuyoshi Nagamine, Takeo Asaga, Hirotaka FuruyaAbstract:The X-ray CT technology previously developed by JAEA was upgraded. The shape of the X-ray source beam was changed from a circular shape to an elliptical one and the collimator slit width was decreased from 0.3 to 0.1 mm. The X-ray detector was improved by changing a CdWO4 scintillator to a highly sensitive silicon semiconductor detector. The analysis code of X-ray CT image was revised with respect to the number of points by using two kinds of experimental results and taking into account the effects of crack existence and deviation of the Central Void position from the radial center of a fuel pellet. As a result, high resolution X-ray CT images could be obtained on the transverse cross section of irradiated fuel assemblies. The error of the dimensional measurement was improved from ±0.1 to ±0.03 mm by upgrading the instrument and revising the analysis code of X-ray CT image. The discriminating accuracy of density difference could be increased, and the low density region (undisturbed region) and high densit...
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application of x ray computer tomography for observing the Central Void formations and the fuel pin deformations of irradiated fbr fuel assemblies
International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications, 2009Co-Authors: Kozo Katsuyama, Tsuyoshi Nagamine, Hirotaka FuruyaAbstract:In order to observe the structural change in the interior of irradiated fuel assemblies, a non-destructive post-irradiation examination (PIE) technique using X-ray computer tomography (X-ray CT) was developed. This X-ray CT technique was applied to observe the Central Void formations and fuel pin deformations of fuel assemblies which had been irradiated at high linear heat rating. The Central Void sizes in all fuel pins were measured on five cross sections of the core fuel column as a parameter for evaluating fuel thermal performance. In addition, the fuel pin deformations were analyzed from X-ray CT images obtained along the axial direction of a fuel assembly at the same separation interval. A dependence of Void size on the linear heat rating was seen in the fuel assembly irradiated at high linear heat rating. In addition, significant undulations of the fuel pin were observed along the axial direction, coinciding with the wrapping wire pitch in the core fuel column. Application of the developed technique should provide enhanced resolution of measurements and simplify fuel PIEs.
Koji Maeda - One of the best experts on this subject based on the ideXlab platform.
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oxide metal ratio dependence of Central Void formation of mixed oxide fuel irradiated in fast reactors
Nuclear Technology, 2017Co-Authors: Yoshihisa Ikusawa, Koji Maeda, Masato Kato, Masayoshi UnoAbstract:AbstractBased on thermal computation results obtained using an irradiation behavior analysis code, we have evaluated the effect of oxide-metal ratio on fuel restructuring from the results of postir...
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upgrading of x ray ct technology for analyses of irradiated fbr mox fuel
Journal of Nuclear Science and Technology, 2012Co-Authors: Akihiro Ishimi, Koji Maeda, Kozo Katsuyama, Tsuyoshi Nagamine, Takeo Asaga, Hirotaka FuruyaAbstract:The X-ray CT technology previously developed by JAEA was upgraded. The shape of the X-ray source beam was changed from a circular shape to an elliptical one and the collimator slit width was decreased from 0.3 to 0.1 mm. The X-ray detector was improved by changing a CdWO4 scintillator to a highly sensitive silicon semiconductor detector. The analysis code of X-ray CT image was revised with respect to the number of points by using two kinds of experimental results and taking into account the effects of crack existence and deviation of the Central Void position from the radial center of a fuel pellet. As a result, high resolution X-ray CT images could be obtained on the transverse cross section of irradiated fuel assemblies. The error of the dimensional measurement was improved from ±0.1 to ±0.03 mm by upgrading the instrument and revising the analysis code of X-ray CT image. The discriminating accuracy of density difference could be increased, and the low density region (undisturbed region) and high densit...
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short term irradiation behavior of low density americium doped uranium plutonium mixed oxide fuels irradiated in a fast reactor
Journal of Nuclear Materials, 2011Co-Authors: Koji Maeda, Kozo Katsuyama, Yoshihisa Ikusawa, Seiichiro MaedaAbstract:Abstract A short-term irradiation test (B14) was conducted using the experimental fast reactor Joyo. The objective of the test was to investigate the early thermal behavior of americium-doped uranium–plutonium mixed oxide (Am-MOX) fuels such as fuel restructuring and redistribution of actinides. Four fuel pins which contained 2.4 wt.% americium-doped uranium–plutonium mixed oxide (Am, Pu, U)O 2− x fuels were supplied for testing. Pellet-cladding gap width and oxygen-to-metal (O/M) molar ratio of oxide fuels were determined as experimental parameters. The respective amounts of plutonium and americium in the fuel pellets were 31 and 2.4 wt.%. The fuel pins were irradiated at the maximum linear heating rate of ∼470 W cm −1 in the B14 test. After the irradiation, post-irradiation examinations were conducted. The influences of both pellet-cladding gap width and O/M molar ratio on the fuel restructuring were confirmed, and no fuel melting was observed. Americium and plutonium were similarly redistributed depending on the O/M molar ratio. In the fuel specimen of the highest O/M molar ratio, the difference in contents between americium and plutonium around the Central Void was significant. From the examination results, the margins to the criteria in the thermal design of the fuel pin would be suitable under the expected operating conditions of a conventional fast breeder reactor.
Kozo Katsuyama - One of the best experts on this subject based on the ideXlab platform.
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upgrading of x ray ct technology for analyses of irradiated fbr mox fuel
Journal of Nuclear Science and Technology, 2012Co-Authors: Akihiro Ishimi, Koji Maeda, Kozo Katsuyama, Tsuyoshi Nagamine, Takeo Asaga, Hirotaka FuruyaAbstract:The X-ray CT technology previously developed by JAEA was upgraded. The shape of the X-ray source beam was changed from a circular shape to an elliptical one and the collimator slit width was decreased from 0.3 to 0.1 mm. The X-ray detector was improved by changing a CdWO4 scintillator to a highly sensitive silicon semiconductor detector. The analysis code of X-ray CT image was revised with respect to the number of points by using two kinds of experimental results and taking into account the effects of crack existence and deviation of the Central Void position from the radial center of a fuel pellet. As a result, high resolution X-ray CT images could be obtained on the transverse cross section of irradiated fuel assemblies. The error of the dimensional measurement was improved from ±0.1 to ±0.03 mm by upgrading the instrument and revising the analysis code of X-ray CT image. The discriminating accuracy of density difference could be increased, and the low density region (undisturbed region) and high densit...
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short term irradiation behavior of low density americium doped uranium plutonium mixed oxide fuels irradiated in a fast reactor
Journal of Nuclear Materials, 2011Co-Authors: Koji Maeda, Kozo Katsuyama, Yoshihisa Ikusawa, Seiichiro MaedaAbstract:Abstract A short-term irradiation test (B14) was conducted using the experimental fast reactor Joyo. The objective of the test was to investigate the early thermal behavior of americium-doped uranium–plutonium mixed oxide (Am-MOX) fuels such as fuel restructuring and redistribution of actinides. Four fuel pins which contained 2.4 wt.% americium-doped uranium–plutonium mixed oxide (Am, Pu, U)O 2− x fuels were supplied for testing. Pellet-cladding gap width and oxygen-to-metal (O/M) molar ratio of oxide fuels were determined as experimental parameters. The respective amounts of plutonium and americium in the fuel pellets were 31 and 2.4 wt.%. The fuel pins were irradiated at the maximum linear heating rate of ∼470 W cm −1 in the B14 test. After the irradiation, post-irradiation examinations were conducted. The influences of both pellet-cladding gap width and O/M molar ratio on the fuel restructuring were confirmed, and no fuel melting was observed. Americium and plutonium were similarly redistributed depending on the O/M molar ratio. In the fuel specimen of the highest O/M molar ratio, the difference in contents between americium and plutonium around the Central Void was significant. From the examination results, the margins to the criteria in the thermal design of the fuel pin would be suitable under the expected operating conditions of a conventional fast breeder reactor.
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application of x ray computer tomography for observing the Central Void formations and the fuel pin deformations of irradiated fbr fuel assemblies
International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications, 2009Co-Authors: Kozo Katsuyama, Tsuyoshi Nagamine, Hirotaka FuruyaAbstract:In order to observe the structural change in the interior of irradiated fuel assemblies, a non-destructive post-irradiation examination (PIE) technique using X-ray computer tomography (X-ray CT) was developed. This X-ray CT technique was applied to observe the Central Void formations and fuel pin deformations of fuel assemblies which had been irradiated at high linear heat rating. The Central Void sizes in all fuel pins were measured on five cross sections of the core fuel column as a parameter for evaluating fuel thermal performance. In addition, the fuel pin deformations were analyzed from X-ray CT images obtained along the axial direction of a fuel assembly at the same separation interval. A dependence of Void size on the linear heat rating was seen in the fuel assembly irradiated at high linear heat rating. In addition, significant undulations of the fuel pin were observed along the axial direction, coinciding with the wrapping wire pitch in the core fuel column. Application of the developed technique should provide enhanced resolution of measurements and simplify fuel PIEs.
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high energy x ray ct study on the Central Void formations and the fuel pin deformations of fbr fuel assemblies
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007Co-Authors: Kozo Katsuyama, Tsuyoshi Nagamine, Shinichiro Matsumoto, Seichi SatoAbstract:Abstract The Central Void formations and deformations of fuel pins were investigated in fuel assemblies irradiated to high burn-up, using a non-destructive X-ray CT (computer tomography) technique. In this X-ray CT, the effect of strong gamma ray activity could be reduced to a negligible degree by using the pulse of a high energy X-ray source and detecting the intensity of the transmitted X-rays in synchronization with the generated X-rays. Clear cross-sectional images of fuel assemblies irradiated to high burn-up in a fast breeder reactor were successively obtained, in which the wrapping wires, cladding, pellets and Central Voids could be distinctly seen. The diameter of a typical Central Void measured by X-ray CT agreed with the one obtained by ceramography within an error of 0.1 mm. Based on this result, the dependence of the Central Void diameter on the linear heating rate was analyzed. In addition, the deformation behavior of a fuel pin along its axial direction could be analyzed from 20 stepwise X-ray cross-sectional images obtained in a small interval, and the results obtained showed a good agreement with the predictions calculated by two computer codes.
Tsuyoshi Nagamine - One of the best experts on this subject based on the ideXlab platform.
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upgrading of x ray ct technology for analyses of irradiated fbr mox fuel
Journal of Nuclear Science and Technology, 2012Co-Authors: Akihiro Ishimi, Koji Maeda, Kozo Katsuyama, Tsuyoshi Nagamine, Takeo Asaga, Hirotaka FuruyaAbstract:The X-ray CT technology previously developed by JAEA was upgraded. The shape of the X-ray source beam was changed from a circular shape to an elliptical one and the collimator slit width was decreased from 0.3 to 0.1 mm. The X-ray detector was improved by changing a CdWO4 scintillator to a highly sensitive silicon semiconductor detector. The analysis code of X-ray CT image was revised with respect to the number of points by using two kinds of experimental results and taking into account the effects of crack existence and deviation of the Central Void position from the radial center of a fuel pellet. As a result, high resolution X-ray CT images could be obtained on the transverse cross section of irradiated fuel assemblies. The error of the dimensional measurement was improved from ±0.1 to ±0.03 mm by upgrading the instrument and revising the analysis code of X-ray CT image. The discriminating accuracy of density difference could be increased, and the low density region (undisturbed region) and high densit...
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application of x ray computer tomography for observing the Central Void formations and the fuel pin deformations of irradiated fbr fuel assemblies
International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications, 2009Co-Authors: Kozo Katsuyama, Tsuyoshi Nagamine, Hirotaka FuruyaAbstract:In order to observe the structural change in the interior of irradiated fuel assemblies, a non-destructive post-irradiation examination (PIE) technique using X-ray computer tomography (X-ray CT) was developed. This X-ray CT technique was applied to observe the Central Void formations and fuel pin deformations of fuel assemblies which had been irradiated at high linear heat rating. The Central Void sizes in all fuel pins were measured on five cross sections of the core fuel column as a parameter for evaluating fuel thermal performance. In addition, the fuel pin deformations were analyzed from X-ray CT images obtained along the axial direction of a fuel assembly at the same separation interval. A dependence of Void size on the linear heat rating was seen in the fuel assembly irradiated at high linear heat rating. In addition, significant undulations of the fuel pin were observed along the axial direction, coinciding with the wrapping wire pitch in the core fuel column. Application of the developed technique should provide enhanced resolution of measurements and simplify fuel PIEs.
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high energy x ray ct study on the Central Void formations and the fuel pin deformations of fbr fuel assemblies
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007Co-Authors: Kozo Katsuyama, Tsuyoshi Nagamine, Shinichiro Matsumoto, Seichi SatoAbstract:Abstract The Central Void formations and deformations of fuel pins were investigated in fuel assemblies irradiated to high burn-up, using a non-destructive X-ray CT (computer tomography) technique. In this X-ray CT, the effect of strong gamma ray activity could be reduced to a negligible degree by using the pulse of a high energy X-ray source and detecting the intensity of the transmitted X-rays in synchronization with the generated X-rays. Clear cross-sectional images of fuel assemblies irradiated to high burn-up in a fast breeder reactor were successively obtained, in which the wrapping wires, cladding, pellets and Central Voids could be distinctly seen. The diameter of a typical Central Void measured by X-ray CT agreed with the one obtained by ceramography within an error of 0.1 mm. Based on this result, the dependence of the Central Void diameter on the linear heating rate was analyzed. In addition, the deformation behavior of a fuel pin along its axial direction could be analyzed from 20 stepwise X-ray cross-sectional images obtained in a small interval, and the results obtained showed a good agreement with the predictions calculated by two computer codes.
Kun Chen - One of the best experts on this subject based on the ideXlab platform.
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strain function analysis method for Void closure in the forging process of the large sized steel ingot
Computational Materials Science, 2012Co-Authors: Kun Chen, Yitao Yang, Guangjie ShaoAbstract:Abstract A mathematical methodology for analyzing Void closure in the forging process of steel ingot with a large size was proposed from the view of strain function. A numerical simulation of the forging process was established to describe the distribution field of compressive strain within deformed steel ingot. Then the analytic function of compressive strain distribution was given by mathematical fitting on the basis of Gaussian function (including the models without and with Void). And finally the quantitative relationship between Void closure and compressive strain, namely mathematical expressions of the criterion for Central and non-Central Void closure, was presented by derivation and calculation of this function. The criterion for Central and non-Central Void closure was verified by finite element simulation for a typical steel ingot. This new methodology gives an acute prediction in terms of elimination of Void defects, where the deviation is less than 7%.