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Journal Articles

Verification of fuel assembly bowing analysis model for core deformation reactivity evaluation

Doda, Norihiro; Uwaba, Tomoyuki; Ohgama, Kazuya; Yoshimura, Kazuo; Nemoto, Toshiyuki*; Tanaka, Masaaki; Yamano, Hidemasa

Nihon Kikai Gakkai Kanto Shibu Dai-29-Ki Sokai, Koenkai Koen Rombunshu (Internet), 5 Pages, 2023/03

An evaluation method for reactivity feedback due to core deformation during reactor power increase in sodium-cooled fast reactors is being developed for realistic core design evaluation. In this evaluation method, fuel assembly bowing was modeled with a beam element of the finite element method, and the assembly's pad contact between adjacent assemblies was modeled with a dedicated element which could consider the wrapper tube cross-sectional distortion and the pad stiffness depending on pad contact conditions. This fuel assembly bowing analysis model was verified for thermal bowing of a single assembly and assembly pad contact between adjacent assemblies in a core as past benchmark problems. The calculation results by this model showed good agreement with those of reference solutions of theoretical solutions or results by participating institutions in the benchmark. This study confirmed that the analysis model was able to calculate thermal assembly bowing appropriately.

Journal Articles

Development of evaluation method for core deformation reactivity feedback in sodium-cooled fast reactor by coupled analysis approach

Doda, Norihiro; Uwaba, Tomoyuki; Yokoyama, Kenji; Nemoto, Toshiyuki*; Tanaka, Masaaki

Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 14 Pages, 2022/03

In sodium-cooled fast reactors, reactivity feedback is generated by thermal deformation of the core fuel assembly during core temperature rise. To utilize the core deformation reactivity as an inherent safety characteristic and to eliminate excessive conservativeness of core design in the safety evaluation, an evaluation method by coupling analyses of neutronics, thermal-hydraulics, and structural deformation has been developed. An experiment of unprotected loss-of-flow event in the experimental fast breeder reactor EBR-II was analyzed. The analysis results show that the core deformation reactivity has a negative feedback effect, and that the deformation reactivity is affected not only by the fuel movement but also by the movement of reflectors around the fuel. As a result, the availability of the evaluation method for core deformation reactivity feedback by coupled analysis approach is confirmed.

Journal Articles

Development of neutronics, thermal-hydraulics, and structure mechanics coupled analysis method on integrated numerical analysis for design optimization support in fast reactor

Doda, Norihiro; Uwaba, Tomoyuki; Nemoto, Toshiyuki*; Yokoyama, Kenji; Tanaka, Masaaki

Keisan Kogaku Koenkai Rombunshu (CD-ROM), 26, 4 Pages, 2021/05

For design optimization of fast reactors, in order to consider the feedback reactivity due to thermal deformation of the core when the core temperature rises, which could not be considered in the conventional design analysis, a neutronics, thermal-hydraulics, and structure mechanics coupled analysis method has been developed. Neutronics code, plant dynamics code, and structural mechanics code are coupled by a control module in python script. This paper outlines the coupling method of analysis codes and the results of its application to an experiment in an actual plant.

Journal Articles

Beam commissioning of the linac for iBNCT

Naito, Fujio*; Anami, Shozo*; Ikegami, Kiyoshi*; Uota, Masahiko*; Ouchi, Toshikatsu*; Onishi, Takahiro*; Oba, Toshiyuki*; Obina, Takashi*; Kawamura, Masato*; Kumada, Hiroaki*; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1244 - 1246, 2016/11

The proton linac installed in the Ibaraki Neutron Medical Research Center is used for production of the intense neutron flux for the Boron Neutron Capture Therapy (BNCT). The linac consists of the 3-MeV RFQ and the 8-MeV DTL. Design average beam current is 10mA. Target is made of Beryllium. First neutron production from the Beryllium target was observed at the end of 2015 with the low intensity beam as a demonstration. After the observation of neutron production, a lot of improvement s was carried out in order to increase the proton beam intensity for the real beam commissioning. The beam commissioning has been started on May 2016. The status of the commissioning is summarized in this report.

Journal Articles

Drift simulation of tsunami debris in the North Pacific

Kawamura, Hideyuki; Kobayashi, Takuya; Nishikawa, Shiro*; Ishikawa, Yoichi*; Usui, Norihisa*; Kamachi, Masafumi*; Aso, Noriko*; Tanaka, Yusuke*; Awaji, Toshiyuki*

Global Environmental Research (Internet), 18(1), p.81 - 96, 2014/09

A drift simulation of tsunami debris flushed out from the Tohoku district, Japan, into the North Pacific due to the tsunami on March 11, 2011, has been conducted to monitor and forecast the drift path over the North Pacific. Results showed that tsunami debris was first transported eastward by the intense Kuroshio Extension and westerly, spreading in the north and south directions by both an energetic ocean eddy and a storm track over the ocean. Tsunami debris with larger windage was transported over the North Pacific by ocean surface wind rather than ocean current and arrived at the west coast of the North American Continent in the fall of 2011. Tsunami debris located near the North American Continent migrated, associated with the basin-scale seasonal change in the atmospheric pressure pattern. Our forecast run suggested that the tsunami debris belt will be formed from the North American Continent in the east to the Philippines in the west.

Journal Articles

Observation of a $$p$$-wave one-neutron halo configuration on $$^{37}$$Mg

Kobayashi, Nobuyuki*; Nakamura, Takashi*; Kondo, Yosuke*; Tostevin, J. A.*; Utsuno, Yutaka; Aoi, Nori*; Baba, Hidetada*; Barthelemy, R.*; Famiano, M. A.*; Fukuda, Naoki*; et al.

Physical Review Letters, 112(24), p.242501_1 - 242501_5, 2014/06

 Times Cited Count:81 Percentile:94.26(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Electrooxidation of hydrazine hydrate using Ni-La catalyst for anion exchange membrane fuel cells

Sakamoto, Tomokazu*; Asazawa, Koichiro*; Martinez, U.*; Halevi, B.*; Suzuki, Toshiyuki*; Arai, Shigeo*; Matsumura, Daiju; Nishihata, Yasuo; Atanassov, P.*; Tanaka, Hirohisa*

Journal of Power Sources, 234, p.252 - 259, 2013/07

 Times Cited Count:65 Percentile:87.41(Chemistry, Physical)

Journal Articles

Hydrological gravity response detection using a gPhone below- and aboveground

Tanaka, Toshiyuki*; Miyajima, Rikio*; Asai, Hideaki*; Horiuchi, Yasuharu; Kumada, Koji; Asai, Yasuhiro*; Ishii, Hiroshi*

Earth Planets and Space, 65(2), p.59 - 66, 2013/02

 Times Cited Count:8 Percentile:25.3(Geosciences, Multidisciplinary)

Journal Articles

Interaction of soft X-ray laser pulse radiation with aluminum surface; Nano-meter size surface modification

Ishino, Masahiko; Faenov, A.*; Tanaka, Momoko; Hasegawa, Noboru; Nishikino, Masaharu; Tamotsu, Satoshi*; Pikuz, S.*; Inogamov, N. A.*; Zhakhovsky, V. V.*; Skobelev, I.*; et al.

AIP Conference Proceedings 1465, p.236 - 240, 2012/07

 Times Cited Count:2 Percentile:64.56

We irradiated the focusing soft X-ray laser pulses having a wavelength of 13.9 nm and the duration of 7 ps to aluminum surface. After the irradiation process, the irradiated surface was observed with a scanning electron microscope. The surface modifications caused by soft X-ray laser single pulse exposure were clearly seen. In addition, it was found that the conical structures having around 100 nm in diameters were formed in the shallow features. The nano-meter size modified surface structures on aluminum induced by the soft X-ray laser pulse is interesting as the newly surface structure. Hence, the soft X-ray laser beam would be a candidate for a tool of micromachining. We also provide a thermomechanical modeling of the soft X-ray laser interaction with aluminum briefly to explain the surface modification.

Journal Articles

Nanomodification of gold surface by picosecond soft X-ray laser pulse

Norman, G.*; Starikov, S.*; Stegailov, V.*; Fortov, V.*; Skobelev, I.*; Pikuz, T.; Faenov, A.*; Tamotsu, Satoshi*; Kato, Yoshiaki*; Ishino, Masahiko; et al.

Journal of Applied Physics, 112(1), p.013104_1 - 013104_8, 2012/07

 Times Cited Count:41 Percentile:83.31(Physics, Applied)

Journal Articles

Surface modifications of metals induced by soft X-ray laser pulse irradiations

Ishino, Masahiko; Faenov, A. Y.*; Tanaka, Momoko; Hasegawa, Noboru; Nishikino, Masaharu; Tamotsu, Satoshi*; Pikuz, T.; Oba, Toshiyuki*; Kaihori, Takeshi; Kawachi, Tetsuya

Journal of Laser Micro/Nanoengineering, 7(2), p.147 - 151, 2012/05

 Times Cited Count:5 Percentile:28.9(Nanoscience & Nanotechnology)

We irradiated the soft X-ray laser (SXRL) pulses having a wavelength of 13.9 nm, the duration time of 7 ps to aluminum (Al), copper (Cu) and gold (Au) surfaces. After the irradiation processes of SXRL beam with laser flux of $$sim$$14 mJ/cm$$^{2}$$ for Al case and of $$sim$$21 mJ/cm$$^{2}$$ for Cu and Au cases, the modified surfaces were observed with the visible microscope, the scanning electron microscope, and the atomic force microscope. The surface modifications caused by the SXRL irradiations were clearly seen on the surfaces, and it was found that the conical structures having around 100 nm in diameters were formed on the Al surface under a single pulse shot. The conical structures were formed in the features with the average depth of about 40 nm, and this value was in accordance with the attenuation length of the SXRL beam for Al. The modified structure on Al surface induced by SXRL pulse irradiations is different from those of Cu and Au surfaces. The modified structure formed on Al surface induced by the SXRL pulse exposure is interesting as the newly structure. Hence, the SXRL beam would be a candidate for a tool of micromachining, which enable to fabricate of three dimensional structures with nano-meter size on Al surface.

Journal Articles

MgO-based inert matrix fuels for a minor actinides recycling in a fast reactor cycle

Miwa, Shuhei; Osaka, Masahiko; Usuki, Toshiyuki; Sato, Isamu; Tanaka, Kosuke; Hirosawa, Takashi; Yoshimochi, Hiroshi; Onose, Shoji

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 8 Pages, 2011/12

A new fast reactor (FR) cycle concept was previously proposed that incorporates MgO-based inert matrix fuels (IMFs) containing minor actinides harmonious with the existing FR cycle technologies. A basic study of MgO-based IMFs was made regarding their fabrication, characterization and reprocessing in terms of applicability to existing FR cycle technology. It was concluded from these basic investigations of MgO-based IMFs that the existing FR cycle technologies can be applied to those for MgO-based IMFs, and the basic technologies of MgO-based IMFs containing minor actinides harmonious with the existing FR cycle technologies were established.

Journal Articles

Source development and novel applications of laser-driven plasma X-ray lasers in JAEA

Kawachi, Tetsuya; Hasegawa, Noboru; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Oba, Toshiyuki; Kaihori, Takeshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; et al.

X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.15 - 24, 2011/12

This paper reviews recent improvement in the source development of laser-driven X-ray lasers and the applications in the research fields of material science, laser processing, X-ray imaging, and radiation damage in biological cells. In the application for material science, we have firstly observed temporal correlation between the domain structures of ferro-electric substance under the Curie temperature. In the laser processing, new X-ray laser interferometer reveals us the nano-scale surface distortion of substance pumped by a femto-second optical pulse. In the X-ray diffraction image, we have taken several static images of micro-structure of samples: now we are trying to extend the objective to nano-scale dynamics using pump and probe method. In the radiation damage of biological cells, we observed double strand break in DNA using X-ray laser exposure; this results are compared with the case using incoherent several KeV X-ray exposure.

Journal Articles

Development of the X-ray interferometer and the method of spatial and temporal synchronization of XRL and optical pulse

Hasegawa, Noboru; Ochi, Yoshihiro; Kawachi, Tetsuya; Terakawa, Kota*; Tomita, Takuro*; Yamamoto, Minoru; Nishikino, Masaharu; Oba, Toshiyuki; Kaihori, Takeshi; Imazono, Takashi; et al.

X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.353 - 358, 2011/12

The understanding of the dynamics of the initial process is important for the micro processing and welding by the ultra-short laser pulse. The X-ray laser is suitable for probing this initial process because it has short wavelength (Ni-like Ag, 13.9 nm) and short duration (7 ps). For this investigation, the origin of time of the pumping pulse is quite important. In this study, we used the scintillation plate and the plasma gate technique to realize the spatial and temporal synchronization of the pump and probe pulses. For the spatial alignment, a CsI scintillation plate that was set at the sample position was illuminated by both the X-ray laser pulse, and the fluorescence light were detected by the CCD camera. For the temporal synchronization, we set a thin foil at the sample position. We measured the transmission of the X-ray laser while changing a temporal delay of the pumping laser with respect to the time of X-ray laser pulse to obtain the origin of the irradiation time.

Journal Articles

Reformation of hazardous wastes into useful supporting materials for fast reactor fuels

Osaka, Masahiko; Miwa, Shuhei; Tanaka, Kosuke; Akutsu, Yoko; Ikeda, Kaoru*; Mimura, Hitoshi*; Suzuki, Tatsuya*; Usuki, Toshiyuki; Yano, Toyohiko*

Annals of Nuclear Energy, 38(12), p.2661 - 2666, 2011/10

 Times Cited Count:2 Percentile:18.92(Nuclear Science & Technology)

Novel concepts for effective utilization of molybdenum (Mo) from nuclear waste and magnesium silicates from hazardous asbestos wastes are proposed. A fast reactor cycle scheme that incorporates each material is described in the present paper. Basic studies on some fundamental technologies for the present cycle are given. Basic separation aspects for Mo by using LIX63 micro capsules and tertiary pyridine resin were investigated. A simple chemical synthesis route for Mo precursor powder from Mo containing HNO$$_{3}$$ solution was tested. Effects of impurities in recovered Mo on sintering behavior were experimentally investigated.

Journal Articles

Measurement of reaction rates in Li/V-alloy assembly with 14 MeV neutron irradiation

Tanaka, Teruya*; Sato, Satoshi; Kondo, Keitaro; Ochiai, Kentaro; Murata, Isao*; Takakura, Kosuke; Sato, Fuminobu*; Kada, Wataru*; Iida, Toshiyuki*; Konno, Chikara; et al.

Fusion Science and Technology, 60(2), p.681 - 686, 2011/08

 Times Cited Count:1 Percentile:10.97(Nuclear Science & Technology)

Irradiation experiments of 14 MeV neutrons have been performed on a Li block assembly of 46 $$times$$ 51 $$times$$ 51 cm$$^3$$ with a 5 cm thick V-alloy layer inside to examine the accuracy of neutronics calculations for the Li/V-alloy blanket design. Foils of Nb, Ni, In and Au for reaction rate measurements of $$^{93}$$Nb(n,2n)$$^{rm 92m}$$Nb, $$^{58}$$Ni(n,p)$$^{58}$$Co, $$^{115}$$In(n,n')$$^{rm 115m}$$In, $$^{197}$$Au(n,$$gamma$$)$$^{198}$$Au reactions and $$^6$$Li enriched ($$^6$$Li: 95.5%) and $$^7$$Li enriched ($$^7$$Li: 99.9%) Li$$_2$$CO$$_3$$ pellets for tritium production rate measurements were installed in the assembly. Results of the measurements were compared with those of calculations with MCNP5, JENDL-3.3 and JENDL/D-99. The comparisons for the reaction rates in the Nb, Ni and In foils indicate that measurements and calculations of the fast neutron transport are consistent almost within 10%. In the comparison for the reaction rates in the Au foils, the underestimation of 15% was found at a surface of the V-alloy layer. There is a possibility that this is due to the elastic scattering cross section of V around 4 keV as previously reported. The comparisons for tritium production rates in the $$^6$$Li enriched and $$^7$$Li enriched Li$$_2$$CO$$_3$$ pellets indicate that calculated rates were larger than results of the measurements by 2-8% and 1-4%, respectively.

Journal Articles

Laser ablation of gold; Experiment and atomistic simulation

Starikov, S. V.*; Stegailov, V. V.*; Norman, G. E.*; Fortov, V. E.*; Ishino, Masahiko; Tanaka, Momoko; Hasegawa, Noboru; Nishikino, Masaharu; Oba, Toshiyuki*; Kaihori, Takeshi; et al.

JETP Letters, 93(11), p.642 - 647, 2011/04

 Times Cited Count:25 Percentile:75.43(Physics, Multidisciplinary)

JAEA Reports

Supplemental study on dose control for a criticality accident

Kanamori, Masashi; Suto, Toshiyuki; Tanaka, Kenichi*; Takada, Jun*

JAEA-Technology 2011-004, 12 Pages, 2011/03


In the previous report "A Study on Dose Control for JCO Criticality Accident Termination" (JAEA-Technology 2009-043), we discussed how to control the dose received during the termination work of the criticality accident. In this paper, we focused on the difference of the way in which dose rate attenuates between within 100 m from the source point and beyond 100 m and discussed the validity of using log-log plotting/semi-log plotting of dose rate - distance relation in order to extrapolate the dose rate at work place near the criticality accident point. In addition, we studied on the effect of the number of dose rate measurement data to be used for extrapolation. We recommend that about 10 mSv which is a half of 20 mSv annual dose limit should be used as worker's dose control target for the high neutron dose field work to ensure enough safety margin considering the following three points; (1) annual dose limit for workers, (2) dose received before, (3) measurement error.

Journal Articles

Evaluation of ZnO fast scintillator spatial resolution using the FZP-focused X-ray laser

Tanaka, Momoko; Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Oba, Toshiyuki; Kaihori, Takeshi; Ochi, Yoshihiro; et al.

JAEA-Conf 2011-001, p.126 - 128, 2011/03

The spatial resolution of hydrothermal method grown zinc oxide (ZnO) scintillator was evaluated using X-ray laser focused with Fresnel zone plate. The fluorescence image of the ZnO scintillator was measured to be less than 10um using CCD camera coupled with a Schbartzchild expander mirror. The availability of large size ZnO crystal up to 3-inch is quite attractive for future lithography and imaging applications.

JAEA Reports

A Study on dose control for Tokaimura criticality accident termination

Kanamori, Masashi; Suto, Toshiyuki; Tanaka, Kenichi*; Takada, Jun*

JAEA-Technology 2010-042, 11 Pages, 2011/01


JAEA-Technology 2009-043 "A Study on dose control for JCO criticality accident termination", the dose we discuss how to manage termination of the criticality accident at work or (we refer as previously report) As a result, based on the measurements from around 40 m to 100 m, we made a re-evaluation of the dose. Reevaluated doses match with the degree of accuracy 60% to 80% compared with the respective individual dose. In this paper, we validate by these doses by using log-log plots and semi-log plots for the distance from the source approximately 100 m and further attenuation. As a result, if the field is under high doses of neutrons, dose constraint assessment should consider some points, by using 10 mSv, half of the annual limit 20 mSv, as dose reference, the work performed could safely be managed. And summaries the valid range of log-log plots for intense neutron dose estimation.

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