Refine your search:     
Report No.
Search Results: Records 1-20 displayed on this page of 214

Presentation/Publication Type

Initialising ...


Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...


Initialising ...


Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Solidification and re-melting mechanisms of SUS-B$$_{4}$$C eutectic mixture

Sumita, Takehiro; Kitagaki, Toru; Takano, Masahide; Ikeda, Atsushi

Journal of Nuclear Materials, 543, p.152527_1 - 152527_15, 2021/01

Journal Articles

Flexible fuel cycle system for the effective management of plutonium

Fukasawa, Tetsuo*; Hoshino, Kuniyoshi*; Yamashita, Junichi*; Takano, Masahide

Journal of Nuclear Science and Technology, 57(11), p.1215 - 1222, 2020/11

The flexible fuel cycle initiative system (FFCI system) has been developed to reduce spent fuel (SF) amounts, to keep high availability factor for the reprocessing plant and to increase the proliferation resistance for the recovered Pu. The system separates most U from the SF at first, and the residual material called recycle material (RM) which contains Pu, minor actinides, fission products and remaining U will go to Pu(+U) recovery from the RM for Pu utilizing reactor in future. The Pu utilizing reactor is FBR or LWR with MOX fuel. The RM is the buffer material between SF reprocessing and Pu utilizing reactor with compact size and high proliferation resistance, which can suppress the amount of relatively pure Pu. The innovative technologies of FFCI are most U separation and temporary RM storage. They are investigated by the literature survey, fundamental experiments using simulated material and analyses using simulation code. This paper summarizes the feasibility confirmation results of FFCI.

Journal Articles

Thermodynamic and thermophysical properties of the actinide nitrides

Uno, Masayoshi*; Nishi, Tsuyoshi*; Takano, Masahide

Comprehensive Nuclear Materials, 2nd Edition, Vol.7, p.202 - 231, 2020/08

On the thermodynamic and thermophysical properties of the actinide nitrides in Comprehensive Nuclear Materials published by Elsevier as the first edition in 2012, we have revised them by adding some brand-new data. The main topics added are the solid solubility of the actinide nitrides into the zirconium nitride matrix for transmutation fuel, the lattice expansion of actinide nitrides induced by self-irradiation damage, the influence of defects accumulation on thermal conductivity, and the thermal expansion in curium nitride lattice.

JAEA Reports

Development of module for ADS nitride fuel performance analysis

Shibata, Hiroki; Saito, Hiroaki; Hayashi, Hirokazu; Takano, Masahide

JAEA-Data/Code 2019-023, 138 Pages, 2020/03


Transmutation of minor actinides in the form of nitride fuel by the accelerator driven system has been developed to reduce the radiotoxicity and volume in the radioactive wastes. Nitride fuel behavior under irradiation condition is necessary for its design and development. Nitride fuel performance analysis module based on light water reactor fuel performance code, FEMAXI-7, was developed by introducing fundamental properties of nitride pellet, 9Cr-1Mo ferrite cladding, and Pi-Bi coolant. As a result of test analysis with this module, we have understood that the nitride fuel shows excellent behavior under irradiation due to its high thermal conductivity. We found that, however, it may be a main concern that fuel cladding integrity is maintained during irradiation in which pellet-cladding mechanical interaction is increased by He gas release, low creep rate of nitride pellet at low temperatures, and high creep rate of cladding above 873 K.

Journal Articles

Observation of simulated fuel debris using synchrotron radiation

Yoneda, Yasuhiro; Harada, Makoto; Takano, Masahide

Transactions of the Materials Research Society of Japan, 44(2), p.61 - 64, 2019/04

We performed three-dimensional observation of simulated fuel debris using Synchrotron Computed Tomography (CT). CT was used to make the inside of fuel debris clear. The CT observation provides that a clear contrast in the zirconia rich part and concrete rich part. Zirconia heavier than concrete moved to the lower part when crystals precipitate and aggregates near the bottom surface. As a result, phase separation occurs. The phase separation is caused by the difference in the composition ratio of zirconia, and can also be observed difference in crystal growth mode by composition ratio.

Journal Articles

Nitride fuel cycle, 2; R&D for minor actinides transmutation

Takano, Masahide

Wagakuni Shorai Sedai No Enerugi O Ninau Kakunenryo Saikuru; Datsu Tanso Shakai No Enerugi Anzen Hosho; NSA/Commentaries, No.24, p.163 - 167, 2019/03

This article summarizes R&D status of the nitride fuel cycle for minor actinides (MA) transmutation. Status of nitride fuel fabrication, material properties and fuel performance code, pyrochemical reprocessing, and nitrogen-15 enrichment are described.

Journal Articles

Chemical state analysis of simulated corium debris by EXAFS

Okamoto, Yoshihiro; Takano, Masahide

Progress in Nuclear Science and Technology (Internet), 5, p.200 - 203, 2018/11

Chemical state of some simulated corium debris samples containing uranium (fuel), zirconium (fuel cladding), iron (structure material), calcium (cement) and lanthanides (fission products) was investigated by synchrotron radiation based extended X-ray absorption fine structure (EXAFS) analysis. The local structure of uranium for the simulated debris was classified into fluorite UO$$_2$$ structure and C-type structure (stabilized cubic). The U$$_{0.27}$$Zr$$_{0.63}$$Fe$$_{0.05}$$Ca$$_{0.05}$$O$$_2$$ sample, which consists of single phase (C-type), shows slightly shorter U-O distance. It can be concluded that the sample contains pentavalent uranium. The local structure of zirconium for U-Zr-O and U-Zr-Fe-O systems was very close to tetragonal ZrO$$_2$$, while that of zirconium changed to CSZ (calcia stabilized cubic) by adding calcium.

Journal Articles

Reaction of hydrogen peroxide with uranium zirconium oxide solid solution; Zirconium hinders oxidative uranium dissolution

Kumagai, Yuta; Takano, Masahide; Watanabe, Masayuki

Journal of Nuclear Materials, 497, p.54 - 59, 2017/12

 Times Cited Count:3 Percentile:50.46(Materials Science, Multidisciplinary)

We studied oxidative dissolution of uranium and zirconium oxide [(U,Zr)O$$_{2}$$] in aqueous H$$_{2}$$O$$_{2}$$ solution. The interfacial reaction is essential for anticipating how a (U,Zr)O$$_{2}$$-based molten fuel may chemically degrade after a severe accident under influence of ionizing radiation. We conducted our experiments with (U,Zr)O$$_{2}$$ powder and quantitated the H$$_{2}$$O$$_{2}$$ reaction via dissolved U and H$$_{2}$$O$$_{2}$$ concentrations. The dissolution yield relative to H$$_{2}$$O$$_{2}$$ consumption was far less for (U,Zr)O$$_{2}$$ compared to that of UO$$_{2}$$. The reaction kinetics indicates that most of the H$$_{2}$$O$$_{2}$$ catalytically decomposed to O$$_{2}$$ at the surface of (U,Zr)O$$_{2}$$. We confirmed the H$$_{2}$$O$$_{2}$$ catalytic decomposition via O$$_{2}$$ production (quantitative stoichiometric agreement). In addition, post-reaction Raman scattering spectra of the undissolved (U,Zr)O$$_{2}$$ showed no additional peaks (indicating a lack of secondary phase formation). The (U,Zr)O$$_{2}$$ matrix is much more stable than UO$$_{2}$$ against H$$_{2}$$O$$_{2}$$-induced oxidative dissolution.

Journal Articles

Local structure analysis of ZrN, and Dy$$_{0.5}$$Zy$$_{0.5}$$N surrogate materials for fast reactor nitride fuel

Yoneda, Yasuhiro; Tsuji, Takuya; Matsumura, Daiju; Okamoto, Yoshihiro; Takaki, Seiya; Takano, Masahide

Transactions of the Materials Research Society of Japan, 42(2), p.23 - 26, 2017/04

ZnN is a possible candidate for the diluent material for nitride fuels containing transuranium elements. Pellets of inert matrix material ZrN, and surrogate nitride fuel material Dy$$_{0.5}$$Zr$$_{0.5}$$N, are fabricated for the purpose of investigating the crystal structure. Lattice parameters of Dy$$_{1-x}$$Zr$$_x$$N followed the Vegard's low, in spite of the large lattice mismatch ($$sim$$ 7%) between DyN and ZrN. Local structure analysis was performed by X-ray absorption fine structure (XAFS) and atomic pair-distribution function (PDF) methods. The Zr-N nearest neighbor bond distance changed as changing the Dy composition. The complex local structure of DyN and ZrN is related to the preferable effects of ZrN.

Journal Articles

Chlorination of UO$$_{2}$$ and (U,Zr)O$$_{2}$$ solid solution using MoCl$$_{5}$$

Sato, Takumi; Shibata, Hiroki; Hayashi, Hirokazu; Takano, Masahide; Kurata, Masaki

Journal of Nuclear Science and Technology, 52(10), p.1253 - 1258, 2015/10

 Times Cited Count:3 Percentile:74.39(Nuclear Science & Technology)

In order to explore the applicability of the chlorination by MoCl$$_{5}$$ as a potential pretreatment technique for waste treatment of fuel debris by pyrochemical methods, chlorination experiments of UO$$_{2}$$ and (U$$_{0.5}$$Zr$$_{0.5}$$)O$$_{2}$$ simulated fuel debris were carried out in two steps: the first one is a chlorination reaction by homogeneous heating, the second one is a volatilization of molybdenum by-product by heating under temperature gradient condition. Most of UO$$_{2}$$ and (U$$_{0.5}$$Zr$$_{0.5}$$)O$$_{2}$$ powder were converted to UCl$$_{4}$$ or UCl$$_{4}$$ and ZrCl$$_{4}$$ mixture at 573 K, respectively. In the case of (U$$_{0.5}$$Zr$$_{0.5}$$)O$$_{2}$$sintered particle, most of sample was converted to the chlorides because the products evaporated and be separated from sample surface at 773 K, while only the surface of the sample disk was converted to the chlorides at 573 and 673 K. Most of molybdenum by-product and ZrCl$$_{4}$$ were separated from UCl$$_{4}$$ by volatilization at 573 K.

Journal Articles

Fundamental experiments on phase stabilities of Fe-B-C ternary systems

Sudo, Ayako; Nishi, Tsuyoshi; Shirasu, Noriko; Takano, Masahide; Kurata, Masaki

Journal of Nuclear Science and Technology, 52(10), p.1308 - 1312, 2015/10

 Times Cited Count:5 Percentile:46.24(Nuclear Science & Technology)

For understanding the control blade degradation mechanism of BWR, the thermodynamic database for the fuel assembly materials is a useful tool. Although iron, boron, and carbon ternary system is a dominant phase diagram, phase relation data is not sufficient for the region in which the boron and carbon compositions are richer than the eutectic composition. The phase relations of three samples were analyzed by X-ray diffraction, scanning electron microscope and energy dispersed X-ray spectrometry. The results indicate that Fe$$_{3}$$(B,C) phase only exists in the intermediate region at 1273 K and that the solidus temperature widely maintains at about 1400 K for all three samples, which are different from the calculated data using previous thermodynamic database. The difference might be originated from the over-estimations of the interaction parameter between boron and carbon in Fe$$_{3}$$(B,C).

Journal Articles

Thermal conductivity of U-20 wt.%Pu-2 wt.%Am-10 wt.%Zr alloy

Nishi, Tsuyoshi; Nakajima, Kunihisa; Takano, Masahide; Kurata, Masaki; Arita, Yuji*

Journal of Nuclear Materials, 464, p.270 - 274, 2015/09

 Times Cited Count:2 Percentile:74.39(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Chemical composition of insoluble residue generated at the Rokkasho Reprocessing Plant

Yamagishi, Isao; Odakura, Makoto; Ichige, Yoshiaki; Kuroha, Mitsuhiko; Takano, Masahide; Akabori, Mitsuo; Yoshioka, Masahiro*

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1113 - 1119, 2015/09

The characteristics of insoluble residues in fine suspension at the Rokkasho Reprocessing Plant were analyzed. The insoluble residues were washed with oxalic acid solution to dissolve zirconium molybdate residues. XRD profiles of unwashed residues showed the presence of a noble metal alloy, zirconium molybdate, and zirconia, but zirconium molybdate was not found after washing. More than 50% of the Sb-125 and Pu in thee residues was washed out as well. The noble metal alloy composed of Mo, Tc, Ru, Rh, and Pd occupied more than 90% of the total weight of 12 elements (Ca, Cr, Fe, Ni, Zr, Mo, Tc, Ru, Rh, Pd, Te, and U) found in the residues. In consideration of the chemical forms of 12 elements, the alloy-to-residue weight ratio was evaluated to be 64% and 78% with and without 18% of an unknown component, respectively.

Journal Articles

Behavior of Nb$$_{3}$$Sn cable assembled with conduit for ITER central solenoid

Nabara, Yoshihiro; Suwa, Tomone; Takahashi, Yoshikazu; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Sakurai, Takeru; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4200305_1 - 4200305_5, 2015/06

 Times Cited Count:0 Percentile:100(Engineering, Electrical & Electronic)

Journal Articles

Recent progress and future R&D plan of nitride fuel cycle technology for transmutation of minor actinides

Hayashi, Hirokazu; Nishi, Tsuyoshi; Takano, Masahide; Sato, Takumi; Shibata, Hiroki; Kurata, Masaki

NEA/NSC/R(2015)2 (Internet), p.360 - 367, 2015/06

Uranium-free nitride fuel was chosen as the first candidate for transmutation of long-lived minor actinides (MA) using accelerator-driven system (ADS) under the double strata fuel cycle concept by Japan Atomic Energy Agency (JAEA). The advantages of nitride fuel are good thermal properties and large mutual solubility among actinide elements. A pyrochemical process is proposed as the first candidate for the reprocessing of the spent nitride fuel, because this technique has some advantages over aqueous process, such as the resistance to radiation damage, which is an important issue for the fuels containing large amounts of highly radioactive MA. This paper overviews the recent progress and future R&D plan of the study on the nitride fuel cycle technology in JAEA.

Journal Articles

Corrosion of uranium and plutonium dioxides in aqueous solutions

Otobe, Haruyoshi; Kitatsuji, Yoshihiro; Kurata, Masaki; Takano, Masahide

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 11 Pages, 2014/10

The chemical and transport behaviors of Pu and U in the corroded debris must be understood for the criticality safety control of Pu and U in the debris, especially for the removal operations and storage. Therefore, the chemical changes of UO$$_{2}$$ and PuO$$_{2}$$ powders, disks and U and Pu metal disks in H$$_{2}$$O$$_{2}$$ aqueous solution have been checked, where H$$_{2}$$O$$_{2}$$ is formed by the radiolysis of H$$_{2}$$O. As a result, UO$$_{2}$$ changed to hydrated uranium peroxide, whereas the PuO$$_{2}$$ remained unchanged. U metal was more reactive with H$$_{2}$$O$$_{2}$$ aqueous solution than Pu metal. The chemical changes of the mixed UO$$_{2}$$/PuO$$_{2}$$ powders in H$$_{2}$$O$$_{2}$$ aqueous solution have been investigated. The dried slurry of the middle zone of H$$_{2}$$O$$_{2}$$ aqueous solution was mainly composed of hydrated uranium peroxide, whereas the dried powder of the bottom zone was mainly composed of PuO$$_{2}$$.

Journal Articles

Characterization of solidified melt among materials of UO$$_{2}$$ fuel and B$$_{4}$$C control blade

Takano, Masahide; Nishi, Tsuyoshi; Shirasu, Noriko

Journal of Nuclear Science and Technology, 51(7-8), p.859 - 875, 2014/07

 Times Cited Count:14 Percentile:16.7(Nuclear Science & Technology)

To predict phase relationships in the solidified core melt of Fukushima Daiichi Nuclear Power Plants, the solidified melt samples among core materials were prepared by arc melting. Phases and compositions in the samples were determined by X-ray diffraction, microscopy and elemental analysis. The only oxide phase formed is (U,Zr)O$$_{2}$$. The stable metallic phases are Fe-Cr-Ni alloy and Fe$$_{2}$$Zr-type (Fe,Cr,Ni)$$_{2}$$(Zr,U) intermetallic. The borides, ZrB$$_{2}$$ and (Fe,Cr,Ni)$$_{2}$$B, are solidified in the metallic part. Annealing at 1773 K under an oxidizing atmosphere resulted in the oxidation of uranium and zirconium in the alloy and ZrB$$_{2}$$, instead the (Fe,Cr,Ni)$$_{2}$$B and Fe-Cr-Ni alloy became dominant. The metallic zirconium content in the melt is found to be a key factor that determines the phase relationships. As a basic mechanical property, the microhardness of each phase was measured. The borides showed notably higher hardness than any other oxide and metallic phases.

Journal Articles

Thermal expansion and self-irradiation damage in curium nitride lattice

Takano, Masahide; Hayashi, Hirokazu; Minato, Kazuo

Journal of Nuclear Materials, 448(1-3), p.66 - 71, 2014/05

 Times Cited Count:1 Percentile:88.23(Materials Science, Multidisciplinary)

A powder sample of curium nitride (CmN) containing 0.35%-PuN and 3.59%-AmN was prepared by carbothermic nitridation of the oxide. The lattice expansion induced by self-irradiation damage at room temperature was measured as a function of time. The saturated $$Delta$$a/a$$_{0}$$ value was 0.43%, which is greater than those for transuranium dioxides available in literature. The undamaged lattice parameter at 297$$pm$$1 K was determined to be 0.50261$$pm$$0.00006 nm. Temperature dependence of the lattice parameter was measured by a high temperature X-ray diffractometer in the temperature range up to 1375 K. The linear thermal expansion of the lattice from 293 to 1273 K is 0.964% and the corresponding thermal expansion coefficient is 9.84 $$times$$ 10$$^{-6}$$ K$$^{-1}$$. Comparing with the other actinide nitrides, it was found that CmN lies between the higher expansion nitrides (PuN and AmN) and the lower expansion nitrides (UN and NpN).

JAEA Reports

Property database of TRU nitride fuel

Nishi, Tsuyoshi; Arai, Yasuo; Takano, Masahide; Kurata, Masaki

JAEA-Data/Code 2014-001, 45 Pages, 2014/03


The purpose of this study is to prepare a property database of nitride fuel needed for the fuel design of accelerator-driven system (ADS) for transmutation of minor actinide (MA). Nitride fuel of ADS is characterized by high content of Pu and MA as principal components, and addition of a diluent material such as ZrN. Experimental data or evaluated values from the raw data on properties Pu and MA nitrides, and nitride solid solutions containing ZrN are collected and summarized, which cover the properties needed for the fuel design of ADS. They are expressed as an equation as much as possible for corresponding to a variety conditions. Error evaluation is also made as much as possible. Since property data on transuranium (TRU) nitrides are often lacking, those on UN and (U,Pu)N are substitutionally shown in such cases in order to facilitate the fuel design with a tolerable accuracy by complementing the database.

Journal Articles

Sintering and characterization of ZrN and (Dy,Zr)N as surrogate materials for fast reactor nitride fuel

Pukari, M.*; Takano, Masahide

Journal of Nuclear Materials, 444(1-3), p.7 - 13, 2014/01

 Times Cited Count:6 Percentile:45.36(Materials Science, Multidisciplinary)

Pellets of inert matrix material ZrN, and surrogate nitride fuel material (Dy$$_{0.4}$$Zr$$_{0.6}$$)N, are fabricated for the purpose of investigating the origin and the effect of carbon and oxygen impurity concentrations. Oxygen concentrations of up to 1.2 wt% are deliberately introduced into the materials with two separate methods. The achievable pellet densities of these materials, as a function of O content, sintering temperature and dimensional powder properties are determined. O dissolved into (Dy,Zr)N increases the achievable densities to a larger extent than if dissolved into ZrN. The segregation of O-rich phases in ZrN indicates a low O solubility in the material. Oxygen pick-up during the fabrication of the product as well as its exposure to air is demonstrated. The quality of the materials is monitored by the systematic analysis of O, N and C contents throughout the fabrication and sintering processes, supported by XRD and SEM analyses.

214 (Records 1-20 displayed on this page)