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Journal Articles

Tensile properties of irradiated modified 316 stainless steel (PNC316) at slow strain rates

Yano, Yasuhide; Miyazawa, Takeshi; Tanno, Takashi; Akasaka, Naoaki; Yoshitake, Tsunemitsu; Kaito, Takeji; Otsuka, Satoshi

Journal of Nuclear Science and Technology, 8 Pages, 2025/00

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

The effects of strain rate on tensile properties of irradiated modified 316 stainless steel (PNC316) claddings were investigated. PNC316 claddings were irradiated at the experimental fast reactor Joyo using CRT402 control rod assembly at 400$$^{circ}$$C up to 25 dpa. Post-irradiation ring tensile tests were carried out at strain rates of 3.3$$times$$10$$^{-6}$$, 3.3$$times$$10$$^{-7}$$ and 3.3$$times$$10$$^{-8}$$ s$$^{-1}$$ at a test temperature of 350$$^{circ}$$C. The results showed no obvious dependence of all strain rates on tensile properties, although a slight decrease in total elongation was observed at the slowest strain rate of 3.3$$times$$10$$^{-8}$$ s$$^{-1}$$. In addition, only a part of fracture surface at the slowest strain rate showed intergranular type region in the inner surface area, although the grain boundary separation occurred on inner surfaces near the fracture region at all strain rates. It is suggested that presence of a high content of helium near the inner surfaces would be related to the fracture behavior.

JAEA Reports

High-temperature strength of modified type 316 steel for fast reactor fuel before and after neutron irradiation

Miyazawa, Takeshi; Uwaba, Tomoyuki; Yano, Yasuhide; Tanno, Takashi; Otsuka, Satoshi; Onizawa, Takashi; Ando, Masanori; Kaito, Takeji

JAEA-Technology 2024-009, 140 Pages, 2024/10

JAEA-Technology-2024-009.pdf:8.03MB

For the purpose of enhancing the reliability of fast reactor fuel designing using modified type 316 steel, the out-of-pile and in-pile mechanical data of modified type 316 steel cladding tubes and wrapper tubes were statistically analyzed with the knowledge on material science and engineering; the high-temperature strength equations of modified type 316 steel, which can be applied to high-dose neutron irradiation environment, were derived. The out-of-pile high-temperature tensile and creep data of modified type 316 steel cladding tubes and wrapper tubes were derived up to 900$$^{circ}$$C, which is higher than the upper limit temperature of anticipated transient event of fast reactor. Using the extended database, the best-fit equation and the lower limit equation were derived for out-of-pile 0.2% proof strength, ultimate tensile strength and creep rupture strength while the best-fit equation and the upper and lower limit equations for creep strain. Furthermore, the degradation factors for tensile and creep strength, which will be produced by in-reactor environment (i.e., neutron irradiation in liquid sodium), were evaluated using the existing neutron irradiation data of modified type 316 steel, which were derived using the experimental fast reactor Joyo, the French proto-type fast reactor Phenix, the American experimental fast reactor FFTF. The derived equations were validated by the comparison with the experimental data.

Journal Articles

Oxide particles in oxide dispersion strengthened steel neutron-irradiated up to 158 dpa at Joyo

Toyama, Takeshi*; Tanno, Takashi; Yano, Yasuhide; Inoue, Koji*; Nagai, Yasuyoshi*; Otsuka, Satoshi; Miyazawa, Takeshi; Mitsuhara, Masatoshi*; Nakashima, Hideharu*; Onuma, Masato*; et al.

Journal of Nuclear Materials, 599, p.155252_1 - 155252_14, 2024/10

 Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)

We investigated the stability of oxide nano particles in oxide dispersion-strengthened (ODS) steel, which is a promising candidate material for next-generation reactors, under neutron irradiation at high temperature to high doses. MA957, a 14Cr-ODS steel, was irradiated with Joyo in Japan Atomic Energy Agency under irradiation conditions of 130 dpa at 502$$^{circ}$$C, 154 dpa at 589$$^{circ}$$C, and 158 dpa at 709$$^{circ}$$C. Three-dimensional atom probe (3D-AP) and transmission electron microscope (TEM) observation were performed to characterize the oxide particles in the ODS steels. A high number density of Y-Ti-O particle was observed in the unirradiated and irradiated samples. Almost no change in the morphology of the oxide particles, i.e. average diameter, number density, and chemical composition, has been observed in the samples irradiated to 130 dpa at 502$$^{circ}$$C and to 154 dpa at 589$$^{circ}$$C. A slight decrease in number density was observed in the sample irradiated to 158 dpa at 709$$^{circ}$$CC. The hardness of any of the irradiated samples was almost unchanged from that of the unirradiated sample. It was revealed that the oxide particles existed stable, and the strength of the material was sufficiently maintained even after being neutron irradiated to high dose of $$sim$$160 dpa at high temperature up to 700$$^{circ}$$C. A part of this study includes the results of MEXT Innovative Nuclear Research and Development Program Grant Number JPMXD0219214482.

Journal Articles

Creep deformation and rupture behavior of 9Cr-ODS steel cladding tube at high temperatures from 700$$^{circ}$$C to 1000$$^{circ}$$C

Imagawa, Yuya; Hashidate, Ryuta; Miyazawa, Takeshi; Onizawa, Takashi; Otsuka, Satoshi; Yano, Yasuhide; Tanno, Takashi; Kaito, Takeji; Onuma, Masato*; Mitsuhara, Masatoshi*; et al.

Journal of Nuclear Science and Technology, 61(6), p.762 - 777, 2024/06

 Times Cited Count:4 Percentile:62.75(Nuclear Science & Technology)

The Japan Atomic Energy Agency has been developing 9Cr-oxide dispersion strengthened (ODS) steel as a fuel cladding material for sodium-cooled fast reactors (SFRs). Previous studies have formulated the creep rupture equation for 650$$^{circ}$$C to 850$$^{circ}$$C. However, little data have been obtained above 850$$^{circ}$$C, and no equation has been formulated. This study conducted creep tests to evaluate creep strength at 700$$^{circ}$$C to 1000$$^{circ}$$C. Two creep test methods, the internal pressure and ring creep tests under development, were used, and the validation of the ring creep test method was conducted. The results showed that 9Cr-ODS steel undergoes almost no strength change due to the matrix's phase transformation, and a single equation can express a creep rupture strength from 700$$^{circ}$$C to 1000$$^{circ}$$C. In validating the ring creep test method, analysis clarified the effect of stress concentration on the specimen. Plastic deformation occurs at high initial stress and may lead to early rupture. The results will be essential for future creep testing and evaluation of neutron-irradiated 9Cr-ODS steel.

Journal Articles

Formulation of high-temperature strength equation of 9Cr-ODS tempered martensitic steels using the Larson-Miller parameter and life-fraction rule for rupture life assessment in steady-state, transient, and accident conditions of fast reactor fuel

Miyazawa, Takeshi; Tanno, Takashi; Imagawa, Yuya; Hashidate, Ryuta; Yano, Yasuhide; Kaito, Takeji; Otsuka, Satoshi; Mitsuhara, Masatoshi*; Toyama, Takeshi*; Onuma, Masato*; et al.

Journal of Nuclear Materials, 593, p.155008_1 - 155008_16, 2024/05

 Times Cited Count:1 Percentile:57.00(Materials Science, Multidisciplinary)

Journal Articles

Microstructural evolution in tungsten binary alloys under proton and self-ion irradiations at 800$$^{circ}$$C

Miyazawa, Takeshi; Kikuchi, Yuta*; Ando, Masami*; Yu, J.-H.*; Yabuuchi, Kiyohiro*; Nozawa, Takashi*; Tanigawa, Hiroyasu*; Nogami, Shuhei*; Hasegawa, Akira*

Journal of Nuclear Materials, 575, p.154239_1 - 154239_11, 2023/03

 Times Cited Count:4 Percentile:73.39(Materials Science, Multidisciplinary)

Journal Articles

Evaluation of radiation tolerance of perovskite solar cell for use in space

Miyazawa, Yu*; Ikegami, Masashi*; Miyasaka, Tsutomu*; Oshima, Takeshi; Imaizumi, Mitsuru*; Hirose, Kazuyuki*

Proceedings of 42nd IEEE Photovoltaic Specialists Conference (PVSC-42) (CD-ROM), p.1178 - 1181, 2015/06

Journal Articles

Development of novel ion-exchange membranes for electrodialysis of seawater by electron-beam-induced graft polymerization, 4; Polymeric structures of cation-exchange membranes based on nylon-6 film

Miyazawa, Tadashi*; Asari, Yuki*; Miyoshi, Kazuyoshi*; Umeno, Daisuke*; Saito, Kyoichi*; Nagatani, Takeshi*; Yoshikawa, Naohito*; Motokawa, Ryuhei; Koizumi, Satoshi*

Nihon Kaisui Gakkai-Shi, 64(6), p.360 - 365, 2010/12

Journal Articles

High-pressure synthesis and physical properties of new iron (nickel)-based superconductors

Shirage, P. M.*; Miyazawa, Kiichi*; Ishikado, Motoyuki; Kiho, Kunihiro*; Lee, C.-H.*; Takeshita, Nao*; Matsuhata, Hirofumi*; Kumai, Reiji*; Tomioka, Yasuhide*; Ito, Toshimitsu*; et al.

Physica C, 469(9-12), p.355 - 369, 2009/06

 Times Cited Count:40 Percentile:78.95(Physics, Applied)

We have utilized a high-pressure (HP) technique to synthesize a series of newly-discovered iron (nickel)-based superconductors. The effect of (O)-deficiency, variation of $$Ln$$ ions, and the external pressure on $$T$$$$_{rm c}$$ are examined. All the experimental data indicate strong correlation between the crystal structure and the superconductivity of the oxypnictide superconductors. Upper critical field measurement on single crystalline sample of PrFeAsO$$_{1-y}$$ shows the superconducting anisotropy of 5, which is smaller than cuprates. We also demonstrate that HP technique is applicable for the so-called "122" systems.

Journal Articles

Experience on return of research reactor spent fuels in Japan

Sagawa, Hisashi; Koda, Nobuyuki; Hanawa, Nobuhiro; Maruo, Takeshi; Miyazawa, Masataka; Unesaki, Hironobu*; Nakagome, Yoshihiro*

IAEA-TECDOC-1593, p.121 - 128, 2008/06

In Japan, 1,712 of Research Reactor Spent Nuclear fuels (RRSNFs) have been transported to the US successfully since the receipt in accordance with the foreign research reactor spent nuclear fuel acceptance policy started in 1996. Especially, Japan Atomic Energy Agency (JAEA) carried out shipment to the US of eight times and of 1,283 fuel elements in total. This paper describes experiences of RRSNF transportation to the US in Japan.

Journal Articles

Enhanced annealing of the Z$$_{1/2}$$ defect in 4H-SiC epilayers

Storasta, L.*; Tsuchida, Hidekazu*; Miyazawa, Tetsuya*; Oshima, Takeshi

Journal of Applied Physics, 103(1), p.013705_1 - 013705_7, 2008/01

 Times Cited Count:108 Percentile:94.13(Physics, Applied)

A carbon-implantation/annealing method for annealing of defect Z$$_{1/2}$$ in thick 4H-SiC epilayers was studied. Different implantation doses and annealing temperatures were examined to find the optimum conditions for annealing of Z$$_{1/2}$$. As the result, Z$$_{1/2}$$ defects in epilayer with 100 $$mu$$m were annealed by implanting 300 nm carbon atoms at a concentration of 2$$times$$10$$^{19}$$/cm$$^{3}$$ and sbsequent annealing at 1800 $$^{circ}$$C. By this treatment, the carrier lifetime increased from less than 200 ns to over 1 $$mu$$s at room temperature.

Oral presentation

Effect of neutron irradiation on rhenium cluster formation in tungsten and tungsten rhenium alloys and Introduction of the research for aging management of JAEA

Hwang, T.; Hasegawa, Akira*; Tomura, Keiko*; Ebisawa, Naoki*; Toyama, Takeshi*; Nagai, Yasuyoshi*; Fukuda, Makoto*; Miyazawa, Takeshi*; Tanaka, Teruya*; Nogami, Shuhei*

no journal, , 

Oral presentation

Oral presentation

Raman and TEM studies of heat-treated La fullerene soot

Yamamoto, Kazunori; Shamoto, Shinichi; Akasaka, Takeshi*; Wakahara, Takatsugu*; Miyazawa, Kunichi*

no journal, , 

no abstracts in English

Oral presentation

Applicability evaluation of Larson-Miller parameter (LMP)-Life fraction rule to high-temperature strength of 9Cr-ODS steels

Miyazawa, Takeshi; Tanno, Takashi; Imagawa, Yuya; Hashidate, Ryuta; Yano, Yasuhide; Otsuka, Satoshi; Kaito, Takeji; Mitsuhara, Masatoshi*; Nakashima, Hideharu*; Onuma, Masato*; et al.

no journal, , 

no abstracts in English

Oral presentation

Absorption and translocation of radioactive cesium in Cypress planted trees

Hirai, Keizo*; Komatsu, Masafumi*; Akama, Akio*; Noguchi, Kyotaro*; Nagakura, Junko*; Ohashi, Shinta*; Saito, Tetsu*; Kawasaki, Tatsuro*; Yazaki, Kenichi*; Ikeda, Shigeto*; et al.

no journal, , 

no abstracts in English

17 (Records 1-17 displayed on this page)
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