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JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute (FY2020)

Asakura, Kazuki; Shimomura, Yusuke; Donomae, Yasushi; Abe, Kazuyuki; Kitamura, Ryoichi; Miyakoshi, Hiroyuki; Takamatsu, Misao; Sakamoto, Naoki; Isozaki, Ryosuke; Onishi, Takashi; et al.

JAEA-Review 2021-020, 42 Pages, 2021/10

JAEA-Review-2021-020.pdf:2.95MB

The disposal of radioactive waste from the research facility need to calculate from the radioactivity concentration that based on variously nuclear fuels and materials. In Japan Atomic Energy Agency Oarai Research and Development Institute, the study on considering disposal is being advanced among the facilities which generate radioactive waste as well as the facilities which process radioactive waste. This report summarizes a study result in FY2020 about the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute.

Journal Articles

Overview of accident-tolerant fuel R&D program in Japan

Yamashita, Shinichiro; Ioka, Ikuo; Nemoto, Yoshiyuki; Kawanishi, Tomohiro; Kurata, Masaki; Kaji, Yoshiyuki; Fukahori, Tokio; Nozawa, Takashi*; Sato, Daiki*; Murakami, Nozomu*; et al.

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.206 - 216, 2019/09

After the nuclear accident at Fukushima Daiichi Power Plant, research and development (R&D) program for establishing technical basis of accident-tolerant fuel (ATF) started from 2015 in Japan. Since then, both experimental and analytical studies necessary for designing a new light water reactor (LWR) core with ATF candidate materials are being conducted within the Japanese ATF R&D Consortium for implementing ATF to the existing LWRs, accompanying with various technological developments required. Until now, we have accumulated experimental data of the candidate materials by out-of-pile tests, developed fuel evaluation codes to apply to the ATF candidate materials, and evaluated fuel behavior simulating operational and accidental conditions by the developed codes. In this paper, the R&D progresses of the ATF candidate materials considered in Japan are reviewed based on the information available such as proceedings of international conference and academic papers, providing an overview of ATF program in Japan.

Journal Articles

High temperature oxidation test of simulated BWR fuel bundle in steam-starved conditions

Yamazaki, Saishun; Pshenichnikov, A.; Pham, V. H.; Nagae, Yuji; Kurata, Masaki; Tokushima, Kazuyuki*; Aomi, Masaki*; Sakamoto, Kan*

Proceedings of Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2018) (Internet), 8 Pages, 2018/10

It is predictively evaluated that degradation of fuel assembly proceeded in a certain steam-starved condition at the early stage of a SA at 1F unit 2 (BWR). As for PWR fuel assembly, effective steam flow rate was properly indicated by normalizing to a unit of g-H$$_{2}$$O/sec/rod which is used as an important parameter for evaluating fuel degradation progression. Due to the inhomogeneous configuration of BWR fuel assembly, the difference of Zry oxidation and hydrogen uptake between the inside and outside of the channel box cannot be properly evaluated by this normalization. Instead of g-H$$_{2}$$O/sec/rod, proper evaluation unit for BWR configuration is necessary. To accumulate Zry oxidation and hydrogen uptake data for steam-starved conditions, high temperature oxidation tests were performed using a simulated BWR fuel bundle sample. The use of equivalent diameter of the cross section of BWR fuel assembly was proposed for normalization of effective steam flow rate.

Journal Articles

Technical basis of accident tolerant fuel updated under a Japanese R&D project

Yamashita, Shinichiro; Nagase, Fumihisa; Kurata, Masaki; Nozawa, Takashi; Watanabe, Seiichi*; Kirimura, Kazuki*; Kakiuchi, Kazuo*; Kondo, Takao*; Sakamoto, Kan*; Kusagaya, Kazuyuki*; et al.

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 10 Pages, 2017/09

In Japan, the research and development (R&D) project on accident tolerant fuel and other components (ATFs) of light water reactors (LWRs) has been initiated in 2015 for establishing technical basis of ATFs. The Japan Atomic Energy Agency (JAEA) has coordinated and carried out this ATF R&D project in cooperation with power plant providers, fuel venders and universities for making the best use of the experiences, knowledges in commercial uses of zirconium-base alloys (Zircaloy) in LWRs. ATF candidate materials under consideration in the project are FeCrAl steel strengthened by dispersion of fine oxide particles(FeCrAl-ODS) and silicon carbide (SiC) composite, and are expecting to endure severe accident conditions in the reactor core for a longer period of time than the Zircaloy while maintaining or improving fuel performance during normal operations. In this paper, the progresses of the R&D project are reported.

Journal Articles

Analytical study of the applicability of FeCrAl-ODS cladding for BWR

Takano, Sho*; Kusagaya, Kazuyuki*; Goto, Daisuke*; Sakamoto, Kan*; Yamashita, Shinichiro

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 10 Pages, 2017/09

We focused on one of accident tolerant fuel (ATF) materials, Oxide Dispersion Strengthened Fe-Cr-Al Steel (FeCrAl-ODS). There is a reasonable prospect that FeCrAl-ODS is applied to BWRs, but relatively high neutron absorption should be compensated. To decrease adverse neutron economic impact, thin FeCrAl-ODS cladding was designed, and we evaluated characteristics of a core into which 9$$times$$9 Advanced BWR (ABWR) bundles with thin FeCrAl-ODS claddings were loaded. Thin FeCrAl-ODS water rods and channel boxes were also applied. We confirmed that FeCrAl-ODS core reactivity was sufficient by increasing enrichment of UO$$_{2}$$ fuel under the limit of 5 wt%. Moreover, some representative FeCrAl-ODS core characteristics were comparable to zircaloy core. We also confirmed that fuel thermal-mechanical behaviors of thin FeCrAl-ODS cladding at normal operation and transient conditions were acceptable. These results led to a conclusion that FeCrAl-ODS was applicable to BWR in the analysis range of this study.

Journal Articles

Welding technology R&D of Japanese accident tolerant fuel claddings of FeCrAl-ODS steel for BWRS

Kimura, Akihiko*; Yuzawa, Sho*; Sakamoto, Kan*; Hirai, Mutsumi*; Kusagaya, Kazuyuki*; Yamashita, Shinichiro

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 10 Pages, 2017/09

The effect of Al addition on the PRW weldability of ODS steel is shown with the discussion focusing on the microstructure changes by the welding. The ordinary welding methods including electron beam (EB) welding and tungsten inert gas (TIG) welding were also applied to the SUS430 endcap welding to cladding tube made of FeCrAl-ODS steel. The endcap welded ODS steel tube samples were tensile tested at RT. The EB welded FeCrAl-ODS/SUS430 samples broke in the ODS steel tube, indicating that the weld bond is stronger than the ODS base metal. However, the TIG welded FeCrAl-ODS/SUS430 samples broke at a weld bond. X-ray CT scan analysis was performed for the weld bond, and the bonding strength was correlated with the X-ray CT results in order to assess the feasibility of those welding methods for ATF-ODS steel cladding.

Journal Articles

Overview of Japanese development of accident tolerant FeCrAl-ODS fuel claddings for BWRs

Sakamoto, Kan*; Hirai, Mutsumi*; Ukai, Shigeharu*; Kimura, Akihiko*; Yamaji, Akifumi*; Kusagaya, Kazuyuki*; Kondo, Takao*; Yamashita, Shinichiro

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 7 Pages, 2017/09

This paper will show the overview of current status of development of accident tolerant FeCrAl-ODS fuel claddings for BWRs (boiling water reactors) in the program sponsored and organized by the Ministry of Economy, Trade and Industry (METI) of Japan. This program is being carried out to create the technical basis for the practical use of the accident tolerant fuels and the other components in LWRs through multifaceted activities. In the development of FeCrAl-ODS fuel claddings both the experimental and the analytical studies have been performed. The acquisition and accumulation of key material properties of FeCrAl-ODS fuel claddings were conducted by using bar, sheet and tube shaped FeCrAl-ODS materials fabricated in this program to support the evaluations in the analytical studies. A neutron irradiation test was also started in the ORNL High Flux Isotope Reactor (HFIR) to examine the effect of neutron irradiation on the mechanical properties.

Journal Articles

Control blade degradation test under temperature gradient in steam atmosphere

Shibata, Hiroki; Tokushima, Kazuyuki; Sakamoto, Kan*; Kurata, Masaki

Proceedings of Annual Topical Meeting on LWR Fuels with Enhanced Safety and Performance (TopFuel 2016) (USB Flash Drive), p.1033 - 1042, 2016/09

To understand the degradation process of control blade channel, control blade degradation tests using sim-materials were performed under various atmospheres with the temperature increase and temperature gradient conditions. In the steam atmosphere with a flow rate of 0.0125 g/s/rod, control blade, channel box, and fuel rods were degraded, especially at the upper part of the test piece, which was similar to that observed in argon atmosphere test. However, the observed degradation was rather different at a flow rate of 0.0417 g/s/rod. At the upper part of the test piece, only the control blade was degraded preferentially and did not react with channel box wall. In contrast, the eutectic reaction of S.S./B$$_{4}$$C-melt and Zry occurred at the lower part. These observations suggested the existence of a threshold condition for the control rod degradation between 0.0125 and 0.0417 g/s/rod which is significantly affected by the thickness of the oxide layer on Zry.

Journal Articles

Numerical simulation on influence to fluid behavior with a change of flow channel cross-sectional area by a spacer

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Kashika Joho Gakkai-Shi, 35(Suppl.2), p.59 - 60, 2015/09

no abstracts in English

Journal Articles

Liquefaction interaction between oxidized Zircaloy and other fuel assembly components of BWR in the early stage of fuel assembly degradation

Tokushima, Kazuyuki; Shibata, Hiroki; Kurata, Masaki; Sawada, Akihiko*; Sakamoto, Kan*

Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2015), Conference Proceedings, Poster (Internet), p.478 - 485, 2015/00

Two type tests were performed to examine the prevention effect of the oxide layers to liquefaction interaction between Zircaloy and core component materials. The oxide layer of Zircaloy was clearly confirmed to prevent the liquefaction interaction under the temperature of melting point of stainless steel even if the oxide layer on Zircaloy of approximately 30 micro meters, which is thinner than it is predicted to be formed under typical accident condition. The oxide layers were able to be formed even in the region where the gas flow is significantly limited by narrow arrangement. Although the oxide layers at the inner position of upper end plug was hard to form, the prevention effect of the oxide layers was sufficiently observed. The axial variation of the thickness of the oxide layers was observed. It suggested that variation of partial pressure of H$$_{2}$$O should be considered to evaluate the growth rate of the oxide layers for detail.

Journal Articles

Numerical analysis on thermal-hydraulics around a spacer in a supercritical fluid

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Nihon Kikai Gakkai Dai-27-Kai Keisan Rikigaku Koenkai Rombunshu (CD-ROM), 2 Pages, 2014/11

no abstracts in English

Journal Articles

Thermal-hydraulic simulation in simulated subchannels of a nuclear reactor at supercritical pressure condition

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Nihon Kikai Gakkai Dai-26-Kai Keisan Rikigaku Koenkai Rombunshu (CD-ROM), p.703_1 - 703_2, 2013/11

no abstracts in English

Journal Articles

Numerical research on fluid mixing characteristics in a non-heated parallel channel by supercritical freon

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Kashika Joho Gakkai-Shi, 32(Suppl.2), p.239 - 240, 2012/10

In the thermal-hydraulic design of supercritical water-cooled reactors, it is required to establish a thermal-hydraulic analysis method which can simulate the heat transfer and fluid flow characteristics of supercritical fluids precisely. A crossing flow is a phenomenon in which the fluid flowing through the inside of a fuel bundle in the perpendicular direction moves between subchannels to a transverse direction. The crossing flow influences the removal heat of a reactor core greatly. In the present study, results of the preliminary crossing flow simulation are described.

Journal Articles

Preliminary consideration for laser welding simulation

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Kashika Joho Gakkai-Shi, 30(Suppl.2), p.359 - 360, 2010/10

no abstracts in English

Journal Articles

Structural changes in surface and bulk LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$ during electrochemical reaction on epitaxial thin-film electrodes characterized by ${it in situ}$ X-ray scattering

Sakamoto, Kazuyuki*; Hirayama, Masaaki*; Konishi, Hiroaki*; Sonoyama, Noriyuki*; Dupr$'e$, N.*; Guyomard, D.*; Tamura, Kazuhisa; Mizuki, Junichiro; Kanno, Ryoji*

Physical Chemistry Chemical Physics, 12(15), p.3815 - 3823, 2010/04

 Times Cited Count:30 Percentile:74.87(Chemistry, Physical)

Surface and bulk structural changes of LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$ were investigated during electrochemical reaction using synchrotron X-ray scattering and a restricted reaction plane consisting of two dimensional epitaxial-film electrodes. The changes in bulk structure confirmed lithium diffusion through the (110) surface, which was perpendicular to the two-dimensional (2D) edges of the layered structure. No (de)intercalation reaction was observed through the (003) surface at voltages of 3.0-5.0 V. However, intercalation did proceed through the (003) plane below 3.0 V, indicating unusual three-dimensional (3D) lithium diffusion in the over-lithiated 2D structure. During the electrochemical process, the surface of the electrode showed different structure changes from those of the bulk structure. The reaction echanism of the intercalation electrodes for lithium batteries is discussed on the basis of surface and bulk structural changes.

Journal Articles

Surface structure of LiNi$$_{0.8}$$Co$$_{0.2}$$O$$_{2}$$; A New experimental technique using in situ X-ray diffraction and two-dimensional epitaxial film electrodes

Sakamoto, Kazuyuki*; Hirayama, Masaaki*; Sonoyama, Noriyuki*; Mori, Daisuke*; Yamada, Atsuo*; Tamura, Kazuhisa; Mizuki, Junichiro; Kanno, Ryoji*

Chemistry of Materials, 21(13), p.2632 - 2640, 2009/05

 Times Cited Count:35 Percentile:72.9(Chemistry, Physical)

Surface and bulk structural changes in LiNi$$_{0.8}$$Co$$_{0.2}$$O$$_{2}$$ were observed during electrochemical reactions using synchrotron X-ray scattering and a restricted reaction plane of two-dimensional (2D) epitaxial-film electrodes. The bulk structural changes confirmed lithium diffusion through the (110) surface, which is perpendicular to the 2D edges of the layered structure. No (de)intercalation reaction was observed through the (003) surface in the voltage range of 3.0-5.0 V. However, intercalation proceeded below 3.0 V, which indicates unusual three-dimensional lithium diffusion in the 2D structure in the overlithiated state. Structural changes at the electrode surface were different from those in the bulk.

Journal Articles

Development of 7 T Cryogen-free superconducting magnet for gyrotron

Hirose, Ryoichi*; Kamikado, Takeshi*; Okui, Yoshio*; Miyata, Hitoshi*; Shibutani, Kazuyuki*; Ozaki, Osamu*; Sakamoto, Keishi

IEEE Transactions on Applied Superconductivity, 18(2), p.920 - 923, 2008/06

 Times Cited Count:13 Percentile:59.47(Engineering, Electrical & Electronic)

A special type of 7 T 240 mm vertical bore cryogen-free superconducting magnet system was developed. The magnet system consists of three sets of coils which are charged separately. A set of sweep coils are located inside of the main coil. The sweep coil produces only $$pm$$0.2 T but is charged and discharged within 10 seconds so as to control electron trajectory. To avoid quench with the rise of the temperature from the large AC loss, this set of coils are wound with Nb$$_{3}$$Sn conductor. This magnet system will contribute to the fast control of the gyrotron oscillation frequency.

Journal Articles

Characterization of electrode/electrolyte interface using ${it in situ}$ X-ray reflectometry and LiNi$$_{0.8}$$Co$$_{0.2}$$O$$_{2}$$ epitaxial film electrode synthesized by pulsed laser deposition method

Hirayama, Masaaki*; Sakamoto, Kazuyuki*; Hiraide, Tetsuya*; Mori, Daisuke*; Yamada, Atsuo*; Kanno, Ryoji*; Sonoyama, Noriyuki*; Tamura, Kazuhisa; Mizuki, Junichiro

Electrochimica Acta, 53(2), p.871 - 881, 2007/12

 Times Cited Count:38 Percentile:65(Electrochemistry)

An ${it in situ}$ experimental technique was developed for detecting structure changes at the electrode/electrolyte interface of lithium cell using synchrotron X-ray reflectometry and two-dimensional model electrodes with a restricted lattice plane. The electrode was constructed with an epitaxial film of LiNi$$_{0.8}$$Co$$_{0.2}$$O$$_{2}$$ synthesized by the pulsed laser deposition method. These films provided an ideal reaction field suitable for detecting structure changes at the electrode/electrolyte interface during the electrochemical reaction. The X-ray reflectometry indicated a formation of a thin-film layer at the LiNi$$_{0.8}$$Co$$_{0.2}$$O$$_{2}$$ (1 1 0)/electrolyte interface during the first charge-discharge cycle, while the LiNi$$_{0.8}$$Co$$_{0.2}$$O$$_{2}$$ (0 0 3) surface showed an increase in the surface roughness without forming the surface thin-film layer.

Journal Articles

Mechanistic study on lithium intercalation using a restricted reaction field in LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$

Sakamoto, Kazuyuki*; Konishi, Hiroaki*; Sonoyama, Noriyuki*; Yamada, Atsuo*; Tamura, Kazuhisa; Mizuki, Junichiro; Kanno, Ryoji*

Journal of Power Sources, 174(2), p.678 - 682, 2007/12

 Times Cited Count:21 Percentile:58.03(Chemistry, Physical)

Structure changes of LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$ were detected at the electrode/electrolyte interface of lithium cell using synchrotron X-ray scattering and two-dimensional model electrodes. The electrodes were constructed by an epitaxial film of LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$ synthesized by pulsed laser deposition (PLD) method. The orientation of the film depends on the substrate plane; the 2D layer of LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$ is parallel to the SrTiO$$_{3}$$(1 1 0) substrate ((1 1 0) LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$//(1 1 0) SrTiO$$_{3}$$), while the 2D layer is perpendicular to the SrTiO$$_{3}$$(1 1 1) substrate ((0 0 3) LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$//(1 1 1) SrTiO$$_{3}$$). The ${it in situ}$ X-ray diffraction of LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$(0 0 3) confirmed three-dimensional lithium diffusion through the two-dimensional transition meal layers. The intercalation reaction of LiNi$$_{0.5}$$Mn$$_{0.5}$$O$$_{2}$$ will be discussed.

Journal Articles

Large scale MD simulation of 8-oxoguanine and AP site multiple lesioned DNA molecule combined with biomolecular visualization software

Fujimoto, Hirofumi; Pinak, M.; Nemoto, Toshiyuki*; Sakamoto, Kiyotaka*; Yamada, Kazuyuki*; Hoshi, Yoshiyuki*; Kume, Etsuo

Journal of Molecular Structure; THEOCHEM, 681(1-3), p.1 - 8, 2004/01

We developed the novel system, Fujitsu Bio Molecular Visualization System (F-BMVS), that enables to produce real pictures and an animation by arranging them along a time series of a large scale simulation of biomolecules associated with a molecular dynamics (MD) simulation program. This animation system is used to study the results of molecular dynamics code, AMBER, in order to find structural differences on the lesioned DNA comparing with non-damaged DNA. These structural differences would be a factor that guides a repair enzyme to discriminate a lesion from non-damaged DNA region.

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