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Journal Articles

Verification of probabilistic fracture mechanics analysis code PASCAL for reactor pressure vessel

Lu, K.; Takamizawa, Hisashi; Li, Y.; Masaki, Koichi*; Takagoshi, Daiki*; Nagai, Masaki*; Nannichi, Takashi*; Murakami, Kenta*; Kanto, Yasuhiro*; Yashirodai, Kenji*; et al.

Mechanical Engineering Journal (Internet), 10(4), p.22-00484_1 - 22-00484_13, 2023/08

Journal Articles

Mechanical properties of pure tungsten and tantalum irradiated by protons and neutrons at the Swiss spallation-neutron source

Saito, Shigeru; Suzuki, Kazuhiro; Obata, Hiroki; Dai, Y.*

Nuclear Materials and Energy (Internet), 34, p.101338_1 - 101338_9, 2023/03

 Times Cited Count:1 Percentile:33.72(Nuclear Science & Technology)

In this study, a post-irradiation examination of pure tungsten (W) and tantalum (Ta) specimens irradiated at the Swiss Spallation-Neutron Source is conducted. W is used as a potential candidate for a solid spallation-target material owing to its favorable properties. However, W also suffers from several disadvantages such as poor corrosion resistance to water coolant and irradiation embrittlement. To improve these properties, cladding technologies using Ta for W alloys have been developed. In the present study, we investigated the irradiation effects on two tungsten materials, poly-crystal W (W-Poly) and single-crystal W (W-Sin), along with pure polycrystalline Ta. The tensile-test results revealed that W-Poly exhibited almost no ductility after irradiation of 10.2-35.0 dpa. W-Sin was irradiated up to 10.2 dpa and demonstrated 6% of total elongation (TE). With regard to Ta, TE decreased based on the increase in irradiation, reaching almost zero at doses of more than 10.3 dpa.

Journal Articles

Two-step Mott transition in Ni(S,Se)$$_2$$; $$mu$$SR studies and charge-spin percolation model

Sheng, Q.*; Kaneko, Tatsuya*; Yamakawa, Kohtaro*; Guguchia, Z.*; Gong, Z.*; Zhao, G.*; Dai, G.*; Jin, C.*; Guo, S.*; Fu, L.*; et al.

Physical Review Research (Internet), 4(3), p.033172_1 - 033172_14, 2022/09

Journal Articles

Experimental validation of tensile properties measured with thick samples taken from MEGAPIE target

Saito, Shigeru; Suzuki, Kazuhiro; Hatakeyama, Yuichi; Suzuki, Miho; Dai, Y.*

Journal of Nuclear Materials, 534, p.152146_1 - 152146_16, 2020/06

 Times Cited Count:1 Percentile:12.47(Materials Science, Multidisciplinary)

A post-irradiation examination (PIE) was performed on the tensile specimens prepared from the MEGAPIE (MEGAwatt Pilot Experiment) target which were irradiated in flowing lead-bismuth eutectic (LBE). Thicknesses of the specimens were over two times larger than that of the standard specimen. The PIE revealed that the T91 specimens showed a 1.5-2.0 times larger total elongation (TE) compared to the literature values for a specimen with standard t/w (ratio of thickness to width). It could be suggested that the t/w and TE were strongly correlated. Then, we tried to investigate the effects of the t/w on the TE by comparing unirradiated specimens. We found that there was no t/w dependence on the strength and uniform elongation. On the other hand, the TE increases with increasing t/w. Based on the experimental data, we correlated the TE with various specimens t/w to estimate appropriate TE values, including that for the standard specimen.

Journal Articles

Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs

Xu, Z.*; Dai, G.*; Li, Y.*; Yin, Z.*; Rong, Y.*; Tian, L.*; Liu, P.*; Wang, H.*; Xing, L.*; Wei, Y.*; et al.

npj Quantum Materials (Internet), 5(1), p.11_1 - 11_7, 2020/02

 Times Cited Count:4 Percentile:41.56(Materials Science, Multidisciplinary)

Journal Articles

Uniaxial pressure effect on the magnetic ordered moment and transition temperatures in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ ($$T$$ = Co,Ni)

Tam, D. M.*; Song, Y.*; Man, H.*; Cheung, S. C.*; Yin, Z.*; Lu, X.*; Wang, W.*; Frandsen, B. A.*; Liu, L.*; Gong, Z.*; et al.

Physical Review B, 95(6), p.060505_1 - 060505_6, 2017/02

 Times Cited Count:23 Percentile:71.84(Materials Science, Multidisciplinary)

Journal Articles

Spin excitations in optimally P-doped BaFe$$_2$$(As$$_{0.7}$$P$$_{0.3}$$)$$_2$$ superconductor

Hu, D.*; Yin, Z.*; Zhang, W.*; Ewings, R. A.*; Ikeuchi, Kazuhiko*; Nakamura, Mitsutaka; Roessli, B.*; Wei, Y.*; Zhao, L.*; Chen, G.*; et al.

Physical Review B, 94(9), p.094504_1 - 094504_7, 2016/09

AA2016-0252.pdf:2.18MB

 Times Cited Count:15 Percentile:59.61(Materials Science, Multidisciplinary)

The temperature and energy dependence of spin excitations in an optimally P-doped BaFe$$_2$$(As$$_{0.7}$$P$$_{0.3}$$)$$_2$$ superconductor (T$$_c$$ = 30 K) were studied by using inelastic neutron scattering. Experimental results are consistent with calculations from a combined density functional theory and dynamical mean field theory, and suggest that the decreased average pnictogen height in BaFe$$_2$$(As$$_{0.7}$$P$$_{0.3}$$)$$_2$$ reduces the strength of electron correlations and increases the effective bandwidth of magnetic excitation.

Journal Articles

Bend-fatigue properties of JPCA and Alloy800H specimens irradiated in a spallation environment

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Endo, Shinya; Sakuraba, Naotoshi; Miyai, Hiromitsu; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 450(1-3), p.27 - 31, 2014/07

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Tensile mechanical properties of a stainless steel irradiated up to 19 dpa in the Swiss spallation neutron source

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Usami, Koji; Endo, Shinya; Ono, Katsuto; Matsui, Hiroki; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 431(1-3), p.44 - 51, 2012/12

 Times Cited Count:2 Percentile:17.83(Materials Science, Multidisciplinary)

To evaluate the lifetime of the beam window of an accelerator-driven transmutation system (ADS), post irradiation examination (PIE) of the STIP (SINQ target irradiation program, SINQ; Swiss spallation neutron source) specimens was carried out. The specimens tested in this study were made from the austenitic steel JPCA (Japan primary candidate alloy). The specimens were irradiated at SINQ Target 4 (STIP-II) with high-energy protons and spallation neutrons. The irradiation conditions were as follows: the proton energy was 580 MeV, irradiation temperatures ranged from 100 to 430$$^{circ}$$C, and displacement damage levels ranged from 7.1 to 19.5 dpa. Tensile tests were performed in air at room temperature (R.T.), 250$$^{circ}$$C and 350$$^{circ}$$C. Fracture surface observation after the tests was done by SEM (Scanning electron microscope). Results of the tensile tests performed at R.T. showed the extra hardening of JPCA at higher dose compared to the fission neutron irradiated data. At the higher temperatures, 250$$^{circ}$$C and 350$$^{circ}$$C, the extra hardening was not observed. Degradation of ductility bottomed around 10 dpa, and specimens kept their ductility until 19.5 dpa. All specimens fractured in ductile manner. The result from a microstructure observation on a specimen irradiated to 19.3 dpa at 420$$^{circ}$$C indicates that some agglomeration of bubbles on grain boundaries was observed in the specimen irradiated to 19.3 dpa at 420$$^{circ}$$C. However the tensile specimen irradiated up to 18.4 dpa at 425$$^{circ}$$C still exhibited little loss of ductility. Since He/dpa was very high on SINQ target irradiations, the formation of highly dense small bubbles in the matrix consequently avoided the accumulation of He on grain boundaries, which might have resulted in avoiding grain boundary embrittlement.

JAEA Reports

Technical report on the Korea-Japan software collaboration

Inamura, Yasuhiro; So, J.-Y.*; Nakajima, Kenji; Suzuki, Jiro*; Nakatani, Takeshi; Kajimoto, Ryoichi; Otomo, Toshiya*; Moon, M.-K.*; Lee, C.-H.*; Yasu, Yoshiji*; et al.

JAEA-Technology 2010-047, 74 Pages, 2011/02

JAEA-Technology-2010-047.pdf:15.03MB

This report summarizes the two-year (2007-2009) activities of Korea-Japan collaboration of chopper software development. Here we have described the background of the collaboration and the main part of our work. We also discussed briefly a future plan of our collaboration starting in 2010. Some of detailed description on the management of the collaboration as well as related information is given in appendix.

Journal Articles

Proton irradiation effects on tensile and bend-fatigue properties of welded F82H specimens

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Endo, Shinya; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 398(1-3), p.49 - 58, 2010/03

 Times Cited Count:6 Percentile:40.42(Materials Science, Multidisciplinary)

In several institutes, R&D for an ADS have been progressed. Ferritic / martensitic (F/M) steels are the candidate material for the beam window. To obtain the irradiation data, the PIE work of the SINQ target irradiation program (STIP) specimens was carried out at JAEA. In this study, the results of PIE on F/M steel F82H and its welded joint will be reported. The results of tensile tests indicate that the irradiation hardening occurred with increasing dpa up to 10.1 dpa below 320$$^{circ}$$C irradiation. At higher dose (- 11.8 dpa) and higher temperature (- 380$$^{circ}$$C), irradiation hardening and degradation of ductility relaxed. In this study, all specimens kept its ductility after irradiation and fractured in ductile manner. The fatigue life of F82H base metal is almost the same as that of unirradiated specimens. Though the number of specimen is limited, the fatigue life of F82H EB welded joints seems to increase after irradiation. The fracture surfaces of the specimens showed transgranular morphology. While F82H TIG welded specimens were not fractured by 10$$^{7}$$ cycles.

Journal Articles

Tensile properties of austenitic stainless steels irradiated at SINQ target 3

Saito, Shigeru; Kikuchi, Kenji; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 343(1-3), p.253 - 261, 2005/08

 Times Cited Count:9 Percentile:53.26(Materials Science, Multidisciplinary)

A beam window of a spallation target will be subjected to proton/neutron irradiation, pressure wave and thermal stresses accompanied by high-energy proton beam injection. To obtain the irradiation data, the SINQ target irradiation program (STIP) was initiated in 1996 at Paul Scherrer Institute (PSI) and has been progressing. JAERI takes part in STIP and shares the PIE work. In this study, the results of tensile tests on austenitic stainless steels, JPCA and 316F SS, will be reported. The results indicate that the irradiation causes considerable hardening and degradation of ductility. The YS increases in this study are slightly large in comparison with those irradiated at fission reactor. Strain-to-necking (STN) values show sufficient large ductility of the irradiated JPCA-SA and 316F-SA. The trends of the STN decrease in this study are slightly abrupt in comparison with those irradiated at fission reactor. All specimens, including irradiated at embrittlement temperature for austenitic steels, fractured in ductile manner.

Journal Articles

Bend-fatigue properties of 590 MeV proton irradiated JPCA and 316F SS

Saito, Shigeru; Kikuchi, Kenji; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 329-333(Part1), p.1093 - 1097, 2004/08

 Times Cited Count:6 Percentile:40.81(Materials Science, Multidisciplinary)

In several institutes, research and development for an accelerator-driven spallation neutron source have been progressed. A beam window of a target will be subjected to proton/neutron irradiation, pressure wave and thermal stresses accompanied by high-energy proton beam injection. To obtain the irradiation data, the SINQ target irradiation program (STIP) at Paul Scherrer Institute (PSI) has been progressing. JAERI takes part in STIP and shares the PIE work. The STIP specimens are very small so that we developed a new fatigue-testing machine with ceramic piezoelectric actuator. The results showed that the numbers of cycles to failure (Nf) on the irradiated specimens were less than that of unirradiated specimens. Dpa dependence of Nf was not clearly seen in the irradiation conditions. On the other hand, fracture surface varied with irradiation conditions. Specimens irradiated at low temperature fractured in ductile manner. However, interglanular fractured surface was observed for 316F SS irradiated up to 12.5 dpa at 360$$^{circ}$$C.

Oral presentation

Residual He gas analyses released from JPCA and F82H irradiated at SINQ target 3

Kikuchi, Kenji; Saito, Shigeru; Tsujimoto, Kazufumi; Kawai, Masayoshi*; Dai, Y.*

no journal, , 

STIP specimens irradiated at SINQ target 3 included helium and hydrogen isotopes generated in the spallation reaction process. A total amount of residual gases with having mass four in the specimens were measured by mass spectrometer or helium leak detector. JPCA is a modified austenitic stainless steel by adding Ti. F82H is a reduced-activation ferritic-martensitic steel developed in fusion program. Specimens are TEM disks and pulled tensile specimens. Samples were heated up to 2000$$^{circ}$$C and allresidual gases were released. A amount of gas was compared with the reported values on the different steels and agreed with other data within 50%.

Oral presentation

Achievement and prospect on spallation materials experiment irradiated by high energy proton

Kikuchi, Kenji; Saito, Shigeru; Endo, Shinya; Hamaguchi, Dai; Dai, Y.*

no journal, , 

Proton irradiation experiment has been done by using a facility at PSI, Switzerland. The objectives of this program are to make materials database available to design and validate the concept of accelerator driven system. Number of materials samples was stored in the target irradiated by cyclotron with proton energy of 585 MeV. Irradiated samples were shared and tested internationally at many laboratories inclusive JAEA. Achievement and prospect on spallation materials experiment are summarized and a characterization of spallation damage is stated.

Oral presentation

Radiation intensity in high power liquid metal target

Kikuchi, Kenji; Dai, Y.*

no journal, , 

Proton beam current is 20 mA in a high-power target with beam power of 30 MW and proton energy of 1.5 GeV. Liquid metals will be candidate target materials because of good heat transfer performance and irradiation damage free. Lead bismuth eutectic is thought to be a primary substance from the point of view of target performance and natural resources. In this radiation field material radiation damage is estimated to be 5 DPA (p) and 50 DPA (n) per year, including neutrons from both spallation reaction and reactor core burning processes. SINQ target irradiation program (STIP) provides useful material radiation fields up to 10 DPA due to proton and another 10DPA due to neutron. In order to describe irradiation materials damage, the particle characterization must be from points of views of its energy and a kind of particle. In addition the evaluation of He gas production, which remains in the materials after irradiation, must be done.

Oral presentation

Mechanical properties of beam window materials for ADS irradiated in a spallation environment

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Endo, Shinya; Usami, Koji; Sakuraba, Naotoshi; Miyai, Hiromitsu; Ono, Katsuto; Matsui, Hiroki; Kawai, Masayoshi*; et al.

no journal, , 

no abstracts in English

Oral presentation

Tensile and ductile-brittle properties of the MEGAPIE samples evaluated by small punch (SP) tests

Saito, Shigeru; Wakui, Takashi; Tsukada, Manabu*; Yamashita, Naoki; Sano, Naruto; Dai, Y.*; Futakawa, Masatoshi

no journal, , 

Post irradiation examination (PIE) of the MEGAPIE (MEGAwatt Pilot Experiment) project has been performed on the samples allotted to JAEA. In the experiments, specimens for tensile test are prepared by taking from the component of the MEGAPIE target such as the beam window (BW) of T91. The irradiation temperatures were about 250 $$^{circ}$$C and the displacement-damage levels ranged between 0.75 and 1.74 dpa. After the tensile tests, SP specimens are prepared from the grip part of the tested tensile specimens. Testing temperatures for SP tests ranged from -150$$^{circ}$$C to 250$$^{circ}$$C. From the area of the load-displacement curves (LDC) of the SP tests, ductile-brittle transition temperature (DBTT) was evaluated. Comparison of these data with previous STIP data showed similar values. In addition, the yield stress and ultimate tensile strength were calculated from the SP tests results by applying the conversion equation. These were compared with the results of the tensile tests and found to be in good agreement.

18 (Records 1-18 displayed on this page)
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