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Journal Articles

Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.

Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08

 Times Cited Count:1 Percentile:24.67(Physics, Applied)

To clarify the existence of cation vacancies in Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Journal Articles

Post-irradiation examinations of annular mixed oxide fuels with average burnup 4 and 5% FIMA

Cappia, F.*; Tanaka, Kosuke; Kato, Masato; McClellan, K.*; Harp, J.*

Journal of Nuclear Materials, 533, p.152076_1 - 152076_14, 2020/05

 Times Cited Count:1 Percentile:39.17(Materials Science, Multidisciplinary)

Journal Articles

The Effects of plutonium content and self-irradiation on thermal conductivity of mixed oxide fuel

Ikusawa, Yoshihisa; Morimoto, Kyoichi; Kato, Masato; Saito, Kosuke; Uno, Masayoshi*

Nuclear Technology, 205(3), p.474 - 485, 2019/03

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

This study evaluated the effects of plutonium content and self-irradiation on the thermal conductivity of mixed-oxide (MOX) fuel. Samples of UO$$_{2}$$ fuel and various MOX fuels were tested. The MOX fuels had a range of plutonium contents, and some samples were stored for 20 years. The thermal conductivity of these samples was determined from thermal diffusivity measurements taken via laser flash analysis. Although the thermal conductivity decreased with increasing plutonium content, this effect was slight. The effect of self-irradiation was investigated using the stored samples. The reduction in thermal conductivity caused by self-irradiation depended on the plutonium content, its isotopic composition, and storage time. The reduction in thermal conductivity over 20 years' storage can be predicted from the change of lattice parameter. In addition, the decrease in thermal conductivity caused by self-irradiation was recovered with heat treatment, and recovered almost completely at temperatures over 1200 K. From these evaluation results, we formulated an equation for thermal conductivity that is based on the classical phonon-transport model. This equation can predict the thermal conductivity of MOX fuel thermal conductivity by accounting for the influences of plutonium content and self-irradiation.

Journal Articles

Isotope-selective microscale imaging of radioactive Cs without isobaric interferences using sputtered neutral mass spectrometry with two-step resonant ionization employing newly-developed Ti:Sapphire lasers

Sakamoto, Tetsuo*; Morita, Masato*; Kanenari, Keita*; Tomita, Hideki*; Sonnenschein, V.*; Saito, Kosuke*; Ohashi, Masaya*; Kato, Kotaro*; Iguchi, Tetsuo*; Kawai, Toshihide*; et al.

Analytical Sciences, 34(11), p.1265 - 1270, 2018/11

 Times Cited Count:7 Percentile:39.71(Chemistry, Analytical)

Journal Articles

Development of multi-colored neutron talbot-lau interferometer with absorption grating fabricated by imprinting method of metallic glass

Seki, Yoshichika; Shinohara, Takenao; Parker, J. D.*; Yashiro, Wataru*; Momose, Atsushi*; Kato, Kosuke*; Kato, Hidemi*; Sadeghilaridjani, M.*; Otake, Yoshie*; Kiyanagi, Yoshiaki*

Journal of the Physical Society of Japan, 86(4), p.044001_1 - 044001_5, 2017/03

 Times Cited Count:13 Percentile:75.09(Physics, Multidisciplinary)

For the effective phase imaging at pulsed neutron sources, we have designed and developed the multi-colored Talbot-Lau interferometer which works at several wavelengths. At the Energy Resolved Neutron Imaging System RADEN in J-PARC, we demonstrated its operation by observing the visibilities of moire fringes derived from different wavelengths (0.25, 0.50, and 0.75 nm). We also investigated the variation of moire fringes dependent on the wavelength resolution from 18% to 50% and showed the advantage of pulsed beams. At the central wavelength of 0.5 nm, we have succeeded in interferometric imaging for the samples of metal rods made of aluminum, lead, and copper. An absorption grating as an analyzer was fabricated by imprinting of metallic glass for the first time, and showed a clear moire fringe with the high visibility of 68% and a well-controlled shape in comparison with previous ones fabricated by oblique evaporation of gadolinium.

Journal Articles

Field test around Fukushima Daiichi Nuclear Power Plant site using improved Ce:Gd$$_{3}$$(Al,Ga)$$_{5}$$O$$_{12}$$ scintillator Compton camera mounted on an unmanned helicopter

Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.

Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12

 Times Cited Count:24 Percentile:96.18(Nuclear Science & Technology)

The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 4$$times$$4 to 8$$times$$8 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m $$times$$ 60 m and 65 m $$times$$ 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the $$gamma$$-ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10$$^{circ}$$).

Journal Articles

The Study of the magnetization process of Fe film by magnetic Compton scattering and M$"o$ssbauer spectroscopy

Agui, Akane; Masuda, Ryo*; Kobayashi, Yasuhiro*; Kato, Tadashi*; Emoto, Shun*; Suzuki, Kosuke*; Sakurai, Hiroshi*

Journal of Magnetism and Magnetic Materials, 408, p.41 - 45, 2016/06

AA2015-0849.pdf:1.54MB

 Times Cited Count:4 Percentile:26.78(Materials Science, Multidisciplinary)

We investigated the magnetization process of Fe (110) film using the field dependence of magnetic Compton scattering and M$"o$ssbauer spectroscopy. From the magnetic Compton profiles, the spin and orbital magnetic moment specific magnetization versus magnetizing field curves were obtained. From the M$"o$ssbauer spectra, the angles between the magnetizing field and the magnetic moment were obtained. It was found that the magnetizing field dependence of the ratio between orbital moment and spin moment was related to the angles between the magnetizing field and the magnetic moment. We indicate that the magnetic field dependence of the orbital magnetic moment plays a role in the magnetization process.

Journal Articles

Self-shielding effect of unresolved resonance data in JENDL-4.0

Konno, Chikara; Kato, Yoshinari*; Takakura, Kosuke; Ota, Masayuki; Ochiai, Kentaro; Sato, Satoshi

Progress in Nuclear Science and Technology (Internet), 4, p.606 - 609, 2014/04

At International Conference on Nuclear Data for Science and Technology in 2007 we pointed out that most of unresolved resonance data in JENDL-3.3 have a problem related to self-shielding correction. Here with a simple calculation model we investigated if the newest JENDL, JENDL-4.0, was improved for the problem or not. As a result, it seems that unresolved resonance data in JENDL-4.0 have no problem, but we are afraid that the self-shielding effect for the unresolved resonance data in JENDL-4.0 is too large. New integral experiments for unresolved resonance data are strongly recommended in order to verify unresolved resonance data.

Journal Articles

Benchmark test of JENDL-4.0 with TOF experiments at Osaka Univ./OKTAVIAN

Kato, Yoshinari*; Takakura, Kosuke; Ota, Masayuki; Ochiai, Kentaro; Sato, Satoshi; Konno, Chikara

Progress in Nuclear Science and Technology (Internet), 4, p.596 - 600, 2014/04

We have performed benchmark tests for JENDL-4.0 released last year in shielding and fusion neutronics fields. Now we analyze OKTAVIAN TOF experiments (CF$$_{2}$$, Si, Ti, Cr, Mn, Co, Cu, As, Se, Zr, Nb, Mo, W) with JENDL-4.0 in order to validate JENDL-4.0. For comparison we also do with the older version JENDL-3.3 and other recent nuclear data libraries (ENDF/B-VII.0, JEFF-3.11). The Monte Carlo code MCNP-4C was used for these analyses. We adopted the official ACE files for JENDL-4.0, JENDL-3.3, JEFF-3.1 and ENDF/B-VII.0. As a result, the following results are obtained through comparison between calculation and measured results. (1) Si, As, Se, Mo, W : Calculation results with JENDL-4.0 agree with the measured ones better than those with JENDL-3.3. (2) CF$$_{2}$$, Co, Cu, Ti, Zr : Calculation results with JENDL-4.0 are almost the same as those with JENDL-3.3. (3) Cr, Mn, Nb : Calculation results with JENDL-4.0 are partially better and partially worse than those with JENDL-3.3.

Oral presentation

Development of Monju plant dynamics analysis code, 3; Verification of Super-COPD code based on the test operation data at 40% rated power

Mori, Takero; Araki, Kosuke*; Kato, Mitsuya*; Takano, Masahito*

no journal, , 

An improved analysis model and the actual component characteristic data for the main cooling system are incorporated in Monju plant dynamics analysis code: Super-COPD. The verification of this new analysis model is based on the results of a plant trip test at 40% rated power and on plant control system characteristics.

Oral presentation

Electrical characterization of GaN containing nitrogen vacancies introduced by electron irradiation

Kato, Masashi*; Fukushima, Keisuke*; Kasuga, Masanobu*; Kito, Kosuke*; Ichimura, Masaya*; Kanechika, Masakazu*; Ishiguro, Osamu*; Kachi, Tetsu*; Oshima, Takeshi

no journal, , 

no abstracts in English

Oral presentation

Validation of multigroup library MATXSLIB-J40 based on JENDL-4.0

Konno, Chikara; Kato, Yoshinari; Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi

no journal, , 

JENDL-4, the major revised version of Japanese Evaluated Nuclear Data Library (JENDL), was released in May, 2010. Its official multigroup library MATXSLIB-4.0 of 199 neutron groups and 42 $$gamma$$ groups with up-scattering data and thermal scattering law data was also released in September, 2010. In this study we examined a validation of MATXSLIB-J40 through analyses of benchmark experiments at JAEA/FNS with Sn codes and the Monte Carlo code MCNP. As a result, the following results are obtained. (1) The calculated results with Sn codes and MATXSLIB-J40 agree well with the measured data and the calculated ones with MCNP. The self-shielding correction in MATXSLIB-J40 has no problem. (2) It is notable that thermal neutron peaks, which were hard to represent, are adequately calculated. It is strongly recommended that a multigroup library of the next Fusion Evaluated Nuclear Data Library (FENDL), FENDL-3, should also have 199 neutron groups, up-scattering data and thermal scattering law data.

Oral presentation

Benchmark test of MATXSLIB-J40 produced from JENDL-4.0

Konno, Chikara; Kato, Yoshinari; Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi

no journal, , 

JENDL-4, the major revised version of Japanese Evaluated Nuclear Data Library (JENDL), was released in May, 2010. Its official multigroup library MATXSLIB-4.0 of 199 neutron groups and 42 $$gamma$$ groups with up-scattering data and thermal scattering law data was also released in September, 2010. In this study we examined a validation of MATXSLIB-J40 through analyses of benchmark experiments at JAEA/FNS with Sn codes and the Monte Carlo code MCNP. As a result, the following results are obtained. (1) The calculated results with Sn codes and MATXSLIB-J40 agree well with the measured data and the calculated ones with MCNP. The self-shielding correction in MATXSLIB-J40 has no problem. (2) It is notable that thermal neutron peaks, which were hard to represent, are adequately calculated. It is strongly recommended that a multigroup library of the next Fusion Evaluated Nuclear Data Library (FENDL), FENDL-3, should also have 199 neutron groups, up-scattering data and thermal scattering law data.

Oral presentation

Benchmark test of JENDL-4.0 with TOF experiments at Osaka Univ./OKTAVIAN

Kato, Yoshinari; Ochiai, Kentaro; Takakura, Kosuke; Sato, Satoshi; Konno, Chikara

no journal, , 

We have performed benchmark tests for JENDL-4.0 released last year in shielding and fusion neutronics fields. Now we analyze OKTAVIAN TOF experiments (CF$$_{2}$$, Si, Ti, Cr, Mn, Co, Cu, As, Se, Zr, Nb, Mo, W) with JENDL-4.0 in order to validate JENDL-4.0. For comparison we also do with the older version JENDL-3.3 and other recent nuclear data libraries (ENDF/B-VII.0, JEFF-3.11). The Monte Carlo code MCNP-4C was used for these analyses. We adopted the official ACE files for JENDL-4.0, JENDL-3.3, JEFF-3.1 and ENDF/B-VII.0. As a result, the following results are obtained through comparison between calculation and measured results. (1) As, Se, W: Calculation results with JENDL-4.0 agree with the measured ones better than those with JENDL-3.3. (2) CF$$_{2}$$, Si, Co, Mn, Cu, Ti, Mo, Zr: Calculation results with JENDL-4.0 are almost the same as those with JENDL-3.3. (3) Cr, Nb: Calculation results with JENDL-4.0 are partially better and partially worse than those with JENDL-3.3.

Oral presentation

Benchmark test of JENDL-4.0 with TOF experiments at Osaka Univ./OKTAVIAN, 2

Kato, Yoshinari; Ochiai, Kentaro; Takakura, Kosuke; Sato, Satoshi; Konno, Chikara

no journal, , 

no abstracts in English

Oral presentation

Self-shielding effects of unresolved resonance data in JENDL-4.0

Konno, Chikara; Kato, Yoshinari; Takakura, Kosuke; Ota, Masayuki; Ochiai, Kentaro; Sato, Satoshi

no journal, , 

At International Conference on Nuclear Data for Science and Technology in 2007 we pointed out that most of unresolved resonance data in JENDL-3.3 have a problem related to self-shielding correction. Here with a simple calculation model we investigated if the newest JENDL, JENDL-4.0, was improved for the problem or not. As a result, it seems that unresolved resonance data in JENDL-4.0 have no problem, but we are afraid that the self-shielding effect for the unresolved resonance data in JENDL-4.0 is too large. New integral experiments for unresolved resonance data are strongly recommended in order to verify unresolved resonance data.

Oral presentation

Study on the physical properties of non-stoichiometric oxide fuels with high minor actinide contents, 6; Evaluation of fuel properties for simulated MA containing oxide fuel

Muta, Hiroaki*; Kato, Naoki*; Tanaka, Kosuke; Matsuda, Tetsushi*; Oishi, Yuji*; Kurosaki, Ken*; Yamanaka, Shinsuke*

no journal, , 

Effect of MA and FP addition on thermo-mechanical properties of UO$$_{2}$$ were investigated.

Oral presentation

Study on the physical properties of non-stoichiometric oxide fuels with high minor actinide contents, 7; Estimation of fuel properties for large amount of simulated MA containing oxide fuel

Kato, Naoki*; Muta, Hiroaki*; Tanaka, Kosuke; Matsuda, Tetsushi*; Oishi, Yuji*; Kurosaki, Ken*; Yamanaka, Shinsuke*

no journal, , 

Physical properties of sintered UO$$_{2}$$ specimens containing over 10% simulated MA were investigated. Based on the measured data, a prediction method for the properties was introduced.

Oral presentation

Measures for jamming of a flexible arm fuel handling machine reducing reactor vessel diameter

Chikazawa, Yoshitaka; Aizawa, Kosuke; Kato, Atsushi; Eto, Masao*; Matsunaga, Shoko*

no journal, , 

A next generation sodium cooled reactor introduce a flexible arm fuel handling machine to reduce reactor vessel diameter. In this study, prevention of jamming at the movable parts of the fuel handling machine and recovery from jamming is investigated.

Oral presentation

Resonant laser secondary neutral mass spectrometry for micro imaging of radioactive isotopes, 2

Tomita, Hideki*; Saito, Kosuke*; Ohashi, Masaya*; Sonnenschein, V.*; Kato, Kotaro*; Suzuki, So*; Iguchi, Tetsuo*; Morita, Masato*; Sakamoto, Tetsuo*; Kanenari, Keita*; et al.

no journal, , 

no abstracts in English

24 (Records 1-20 displayed on this page)