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Journal Articles

Study of quasielastic barrier distributions as a step towards the synthesis of superheavy elements with hot fusion reactions

Tanaka, Taiki*; Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Boll, R. A.*; Brewer, N. T.*; Van Cleve, S.*; Dean, D. J.*; Ishizawa, Satoshi*; et al.

Physical Review Letters, 124(5), p.052502_1 - 052502_6, 2020/02

 Times Cited Count:6 Percentile:62.45(Physics, Multidisciplinary)

Journal Articles

High stereographic resolution texture and residual stress evaluation using time-of-flight neutron diffraction

Xu, P. G.; Harjo, S.; Ojima, Mayumi*; Suzuki, Hiroshi; Ito, Takayoshi*; Gong, W.; Vogel, S. C.*; Inoue, Junya*; Tomota, Yo*; Aizawa, Kazuya; et al.

Journal of Applied Crystallography, 51(3), p.746 - 760, 2018/06


 Times Cited Count:18 Percentile:90.21(Chemistry, Multidisciplinary)

Journal Articles

High oxide-ion conductivity in Si-deficient La$$_{9.565}$$(Si$$_{5.826}$$[]$$_{0.174}$$)O$$_{26}$$ apatite without interstitial oxygens due to the overbonded channel oxygens

Fujii, Kotaro*; Yashima, Masatomo*; Hibino, Keisuke*; Shiraiwa, Masahiro*; Fukuda, Koichiro*; Nakayama, Susumu*; Ishizawa, Nobuo*; Hanashima, Takayasu*; Ohara, Takashi

Journal of Materials Chemistry A, 6(23), p.10835 - 10846, 2018/06

 Times Cited Count:19 Percentile:65.98(Chemistry, Physical)

Journal Articles

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

 Times Cited Count:10 Percentile:67.6(Physics, Multidisciplinary)

Excitation functions of quasielastic scattering cross sections for the $$^{48}$$Ca + $$^{208}$$Pb, $$^{50}$$Ti + $$^{208}$$Pb, and $$^{48}$$Ca + $$^{248}$$Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the $$^{48}$$Ca + $$^{208}$$Pb and $$^{50}$$Ti + $$^{208}$$Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the $$^{48}$$Ca + $$^{248}$$Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Journal Articles

Novel electrothermodynamic power generation

Kim, Y.*; Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Ogawa, Takashi*; Serizawa, Takeshi*; Tanaka, Hirohisa*; Baba, Masaaki*; Fukuda, Tatsuo; Yoshii, Kenji; et al.

Advanced Energy Materials, 5(13), p.1401942_1 - 1401942_6, 2015/07

 Times Cited Count:13 Percentile:49.18(Chemistry, Physical)

An innovative electro-thermodynamic cycle based on temporal temperature variations using pyroelectric effect has been presented. Practical energy is successfully generated in both $textit{in-situ}$ synchrotron X-ray diffraction measurements under controlled conditions and $textit{Operando}$ real engine dynamometer experiments. The main generating origin is revealed as a combination of a crystal structure change and dipole change phenomenon corresponds to the temperature variation. In particular, the electric field induced 180$$^circ$$ domain switching extremely improves generating power, and the true energy breakeven with temperature variation is firstly achieved.

Journal Articles

Study on application of PFM analysis method to Japanese code for RPV integrity assessment under PTS events

Osakabe, Kazuya*; Masaki, Koichi*; Katsuyama, Jinya; Katsumata, Genshichiro; Onizawa, Kunio; Yoshimura, Shinobu*

Proceedings of 2015 ASME Pressure Vessels and Piping Conference (PVP 2015) (Internet), 8 Pages, 2015/07

A probabilistic fracture mechanics (PFM) analysis method for pressure boundary components is useful to evaluate the structural integrity in a quantitative way. This is because the uncertainties related to influence parameters can be rationally incorporated in PFM analysis. From this viewpoint, the probabilistic approach evaluating through-wall cracking frequencies (TWCFs) of reactor pressure vessels (RPVs) has already been adopted as the regulation on fracture toughness requirements against PTS events in the U.S. As a study of applying PFM analysis to the integrity assessment of domestic RPVs, JAEA has been preparing input data and analysis models to calculate TWCFs using PFM analysis code PASCAL3. In this paper, activities have been introduced such as preparing input data and models for domestic RPVs, verification of PASCAL3, and formulating guideline on general procedures of PFM analysis for the purpose of utilizing PASCAL3. In addition, TWCFs for a model RPV evaluated by PASCAL3 are presented.

Journal Articles

Stabilization of a high-order harmonic generation seeded extreme ultraviolet free electron laser by time-synchronization control with electro-optic sampling

Tomizawa, Hiromitsu*; Sato, Takahiro*; Ogawa, Kanade*; Togawa, Kazuaki*; Tanaka, Takatsugu*; Hara, Toru*; Yabashi, Makina*; Tanaka, Hitoshi*; Ishikawa, Tetsuya*; Togashi, Tadashi*; et al.

High Power Laser Science and Engineering, 3, p.e14_1 - e14_10, 2015/04

 Times Cited Count:5 Percentile:32.92(Optics)

no abstracts in English

Journal Articles

Fermi surface, magnetic, and superconducting properties in actinide compounds

Onuki, Yoshichika; Settai, Rikio*; Haga, Yoshinori; Machida, Yo*; Izawa, Koichi*; Honda, Fuminori*; Aoki, Dai*

Comptes Rendus Physique, 15(7), p.616 - 629, 2014/08

 Times Cited Count:5 Percentile:42.88(Astronomy & Astrophysics)

Journal Articles

Engineering validation and engineering design of lithium target facility in IFMIF/EVEDA project

Wakai, Eiichi; Kondo, Hiroo; Kanemura, Takuji; Furukawa, Tomohiro; Hirakawa, Yasushi; Watanabe, Kazuyoshi; Ida, Mizuho*; Ito, Yuzuru; Niitsuma, Shigeto; Edao, Yuki; et al.

Fusion Science and Technology, 66(1), p.46 - 56, 2014/07

 Times Cited Count:4 Percentile:34.57(Nuclear Science & Technology)

Journal Articles

Estimation of through-wall cracking frequency of RPV under PTS events using PFM analysis method for identifying conservatism included in current Japanese code

Osakabe, Kazuya*; Masaki, Koichi*; Katsuyama, Jinya; Katsumata, Genshichiro; Onizawa, Kunio

Proceedings of 2014 ASME Pressure Vessels and Piping Conference (PVP 2014) (DVD-ROM), 7 Pages, 2014/07

The structural integrity of reactor pressure vessel (RPV) during pressurized thermal shock events is judged to be maintained unless the stress intensity factors at the crack tip is smaller than fracture toughness $$K$$$$_{Ic}$$ based on deterministic approach in the current Japanese code. Application of a probabilistic fracture mechanics (PFM) analysis method for the structural reliability assessment of RPVs has become attractive recently, because uncertainties of several parameters can be incorporated rationally. According to the PFM analysis method in the U.S., through-wall cracking frequencies (TWCFs) are estimated. In this study, in order to identify the conservatism in the current code, PFM analyses on TWCF have been performed for certain model of RPVs. The result shows that the current assumption in JEAC 4206-2007 is conservative as compared with realistic conditions. Effects of variation of PTS transients on crack initiation frequency and TWCF have been also discussed.

Journal Articles

Pairing symmetry of UPt$$_3$$ probed by thermal transport tensors

Izawa, Koichi*; Machida, Yo*; Ito, Atsushi*; So, Yoshinao*; Ota, Katsuya*; Haga, Yoshinori; Yamamoto, Etsuji; Kimura, Noriaki*; Onuki, Yoshichika; Tsutsumi, Yasumasa*; et al.

Journal of the Physical Society of Japan, 83(6), p.061013_1 - 061013_8, 2014/06

 Times Cited Count:19 Percentile:74.98(Physics, Multidisciplinary)

Journal Articles

Probabilistic structural integrity analysis of reactor pressure vessels during pressurized thermal shock events

Masaki, Koichi; Katsuyama, Jinya; Onizawa, Kunio

Journal of Pressure Vessel Technology, 136(1), p.011208_1 - 011208_7, 2014/02

 Times Cited Count:0 Percentile:0.01(Engineering, Mechanical)

In order to apply a probabilistic fracture mechanics (PFM) analysis to the structural integrity assessment of a reactor pressure vessel (RPV), PFM analysis code has been developed at JAEA. Using the PFM analysis code, PASCAL version 3, the conditional probabilities of crack initiation and fracture for an RPV during pressurized thermal shock events have been analyzed. Sensitivity analyses on some input parameters were performed to clarify the effect on the conditional fracture probability. Comparison between the conditional probabilities and temperature margin from current deterministic analysis method were made for some model plant conditions of domestic typical old-type RPVs. From the analyses, a good correlation between temperature margin and the conditional probability of crack initiation was obtained.

Journal Articles

Effect of partial welding on the residual stress and structural integrity of piping welds

Katsuyama, Jinya; Masaki, Koichi; Onizawa, Kunio

Journal of Pressure Vessel Technology, 135(6), p.061403_1 - 061403_8, 2013/12

 Times Cited Count:0 Percentile:0.01(Engineering, Mechanical)

When weld defects are observed during an inspection after welding, repair welding is performed after removing the defects. However, partial repair welding can potentially complicate the weld residual stress distribution. In this study, we performed thermal-elastic-plastic analyses to evaluate the weld residual stress produced by repair welding after pipe butt-welding. In addition, based on the analysis results for varying repair-welding conditions, we also performed structural integrity assessments related to stress corrosion cracking using the probabilistic fracture mechanics analysis code PASCAL-SP. It was clearly observed that the tensile stress in the repair-welded region increased and that compressive stresses occurred outside the repair-welded region. A deeper mechanical cutting depth caused larger increases in the tensile residual stress of the repair-welded region. It was also clarified that partial repair welding may favorably affect the break probability of piping welds.

Journal Articles

Research and development of radiation measuring instruments for lake,pond and river sediments, 1

Yanagizawa, Koichi; Hayashi, Toshio*; Oinuma, Masaru*; Takemori, Makoto*; Ishikawa, Takanori*; Okaya, Tomoichi*; Nishigaki, Makoto*

Shadan Hojin Butsuri Tansa Gakkai Dai-129-Kai (Heisei-25-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu, p.287 - 288, 2013/10

The development of instrument aimed at the measurement of radiation dose in the sediment of lakes, rivers and sea bed been carried out. The radiation level contained in the sediment at the bottom of lake and so on is anticipated to indicate the existence of locally high radiation spots where the diffused radioactive substance is accumulated in ponds, rivers and lakes by rainwater. The radiation dose measurement system this time is to measure $$gamma$$-ray by dragging the detector, which is called probe, at the bottom of lakes to understand the radiation dose over wide areas. Furthermore, the measurement of resistivity value at the bottom of lakes is simultaneously dose to presume the condition of sediment.

Journal Articles

Fracture mechanics evaluation using PASCAL3 for current structural integrity assessment method for reactor pressure vessel

Nishikawa, Hiroyuki*; Masaki, Koichi*; Katsuyama, Jinya; Onizawa, Kunio

Nihon Genshiryoku Gakkai Wabun Rombunshi, 12(3), p.211 - 221, 2013/09

Probabilistic fracture mechanics analysis code PASCAL3 has been developed at JAEA to support the validation of the codes and standards which provide the structural integrity assessment method of reactor pressure vessels (RPVs) during pressurized thermal shock. Previous version of PASCAL2 has many functions including the evaluation method for an embedded crack, PTS transient database, non-destructive inspection models. This code has been improved mainly focusing on cladding on the inner surface of RPV. Using the PASCAL3 code, effects of the initiation and growth model for a surface flaw have been analyzed to determine the standard condition of PASCAL3. Deterministic and probabilistic evaluation using PASCAL3 for current structural integrity assessment method for RPV has also been conducted. The results show that the consideration of warm pre-stress effect decreases the conditional probability

Journal Articles

Study on the structural integrity of RPV using PFM analysis concerning inhomogeneity of the heat-affected zone

Masaki, Koichi; Katsuyama, Jinya; Onizawa, Kunio

E-Journal of Advanced Maintenance (Internet), 5(2), p.85 - 92, 2013/08

In order to obtain the technical basis to judge the needs of surveillance test specimens from HAZ materials, the features of inhomogeneity of HAZ in RPV steels were investigated. Concerning on the fracture toughness in HAZ, HAZ materials close to weld metal indicated higher toughness than that of base metal due to high-toughness phase, while HAZ materials close to base metal were equivalent or slightly lower toughness than that of base metal due to the same phase as base metal. A structural integrity assessment method concerning such inhomogeneous distribution of fracture toughness for HAZ materials was developed and incorporated into PFM analysis code PASCAL3. Case studies on postulated flaws distribution and chemical composition were performed by using PASCAL3. It was shown that in highly irradiated conditions, CPI and CPF in HAZ close to weld metal are lower than base metal, while those in HAZ close to base metal were almost equivalent to base metal.

Journal Articles

Full-coherent free electron laser seeded by 13th- and 15th-order harmonics of near-infrared femtosecond laser pulses

Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08

 Times Cited Count:3 Percentile:20.56(Optics)

By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10$$^{2}$$ with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.

Journal Articles

Effects of gauge volume on pseudo-strain induced in strain measurement using time-of-flight neutron diffraction

Suzuki, Hiroshi; Harjo, S.; Abe, Jun; Xu, P. G.; Aizawa, Kazuya; Akita, Koichi

Nuclear Instruments and Methods in Physics Research A, 715, p.28 - 38, 2013/07

 Times Cited Count:10 Percentile:65.2(Instruments & Instrumentation)

Effects of gauge volume on pseudo-strains induced in neutron strain measurements using the time-of-flight neutron diffraction due to influences of the neutron attenuation, the surface-effect and a strain distribution were discussed on strain measurements in an annealed and a bent ferritic steel bars. An average strain in a gauge volume was weighted towards a neutron-weighted center of gravity (ncog) position, and the weighted average strain was apparently changed following change in the ncog position with an increase of the gauge volume. On the other hand, typical pseudo-strains due to the surface-effect were appeared in near-surface strain measurements when a gauge volume is incompletely filled in a sample. Furthermore, a pseudo-strain due to change in the ncog position was observed even when perfectly immersing the gauge volume in a sample, and it was increased with an increase of the gauge volume. These pseudo-strains measured were well simulated by taking into account an incident neutron beam divergence additionally in the conventional model. Therefore, it was clarified that the incident neutron beam divergence must be an important parameter to make a modeling of pseudo-strains induced in the strain measurement using the TOF engineering diffractometer.

Journal Articles

A Study for proposal of welded joint strength reduction factors of modified 9Cr-1Mo steel for Japan sodium cooled fast reactor (JSFR)

Wakai, Takashi; Onizawa, Takashi; Kato, Takehiko*; Date, Shingo*; Kikuchi, Koichi*; Sato, Kenichiro*

Proceedings of 2013 ASME Pressure Vessels and Piping Conference (PVP 2013) (DVD-ROM), 8 Pages, 2013/07

Journal Articles

Full-coherent HHG-seeded EUV-FEL locked by EOS timing feedback

Ogawa, Kanade*; Sato, Takahiro*; Matsubara, Shinichi*; Okayasu, Yuichi*; Togashi, Tadashi*; Watanabe, Takahiro*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; et al.

Proceedings of 10th Conference on Lasers and Electro-Optics Pacific Rim and 18th OptoElectronics and Communications Conference and Photonics in Switching 2013 (CLEO-PR & OECC/PS 2013) (USB Flash Drive), 2 Pages, 2013/06

no abstracts in English

138 (Records 1-20 displayed on this page)