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Journal Articles

Fission mechanism inferred from nuclear shape fluctuation by the Langevin equation

Aritomo, Yoshihiro*; Iwamoto, Akira*; Nishio, Katsuhisa; Ota, Masahisa*

Physical Review C, 105(3), p.034604_1 - 034604_8, 2022/03

 Times Cited Count:0 Percentile:0.06(Physics, Nuclear)

Journal Articles

Status of JENDL

Iwamoto, Osamu; Iwamoto, Nobuyuki; Shibata, Keiichi; Ichihara, Akira; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke

EPJ Web of Conferences, 239, p.09002_1 - 09002_6, 2020/09

 Times Cited Count:5 Percentile:98.76

Journal Articles

Status of the JENDL project

Iwamoto, Osamu; Shibata, Keiichi; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Ichihara, Akira; Nakayama, Shinsuke

EPJ Web of Conferences, 146, p.02005_1 - 02005_6, 2017/09

 Times Cited Count:0 Percentile:0.08

Journal Articles

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

 Times Cited Count:17 Percentile:85.71(Materials Science, Multidisciplinary)

Journal Articles

Charge radii in macroscopic-microscopic mass models

Iimura, Hideki; M$"o$ller, P.*; Ichikawa, Takatoshi*; Sagawa, Hiroyuki*; Iwamoto, Akira*

JPS Conference Proceedings (Internet), 6, p.030102_1 - 030102_4, 2015/06

no abstracts in English

Journal Articles

Development of divertor simulation research in the GAMMA 10/PDX tandem mirror

Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10

Journal Articles

Development of a calculation system for the estimation of decontamination effect

Satoh, Daiki; Kojima, Kensuke; Oizumi, Akito; Matsuda, Norihiro; Iwamoto, Hiroki; Kugo, Teruhiko; Sakamoto, Yukio*; Endo, Akira; Okajima, Shigeaki

Journal of Nuclear Science and Technology, 51(5), p.656 - 670, 2014/05

 Times Cited Count:7 Percentile:53.04(Nuclear Science & Technology)

A calculation system for the estimation of decontamination effect (CDE) has been developed to support planning a rational and effective decontamination. The method calculates the dose-rate distribution before and after decontamination, according to the distribution of radioactivity and the decontamination factor (DF), and uses a dose rate reduction factor (DRRF) to estimate the decontamination effect. The results that were calculated by using the CDE were compared with the results of measurements as well as with the results of calculations that were performed using a Monte Carlo particle transport code PHITS. It was found that the CDE successfully reproduced the measured as well as the calculated dose-rate distributions, requiring less than several seconds of calculation time.

Journal Articles

Calculation system for the estimation of decontamination effect

Satoh, Daiki; Kojima, Kensuke; Oizumi, Akito; Matsuda, Norihiro; Iwamoto, Hiroki; Kugo, Teruhiko; Sakamoto, Yukio*; Endo, Akira; Okajima, Shigeaki

Transactions of the American Nuclear Society, 109(1), p.1261 - 1263, 2013/11

A computer software, named CDE (Calculation system for Decontamination Effect), has been developed to support planning the decontamination. CDE is programed with VBA (Visual Basic for Applications), and runs on Microsoft Excel with a user friendly graphical interface. It calculates dose rate distributions in a target area before and after the decontamination from a radioactivity distribution and DF (Decontamination Factor), which is a ratio of original radioactivity to remaining one after the decontamination. DRRF (Dose Rate Reduction Factor) is also derived to express the decontamination effect. All the calculation results are visualized on an image of the target area with color map. Owing to its quick calculation speed, CDE is able to investigate the decontamination effect in various cases for a short period. This is very useful to establish a rational decontamination plan before an action.

Journal Articles

Development of proposed guideline of flow-induced vibration evaluation for hot-leg piping in a sodium-cooled fast reactor

Sakai, Takaaki; Yamano, Hidemasa; Tanaka, Masaaki; Ono, Ayako; Ohshima, Hiroyuki; Kaneko, Tetsuya*; Hirota, Kazuo*; Sago, Hiromi*; Xu, Y.*; Iwamoto, Yukiharu*; et al.

Proceedings of 15th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-15) (USB Flash Drive), 13 Pages, 2013/05

The development of flow-induced vibration evaluation methodology has reached a milestone that separate-effect experimental data under a high Reynolds number regime including swirl and deflected inflow conditions are available for the validation of the methodology. On the other hand, technical standards are desirable to be documented for designers of sodium-cooled fast reactors. From such a background, the documentation of a flow-induced vibration design guideline has been made for the hot-leg piping of Japan sodium-cooled fast reactor. This paper describes the design guideline of the flow-induced vibration evaluation methodology, which has been informed from main separate-effect experiments, as well as supplemental interpretation for the guideline.

Journal Articles

Contrasting fission potential-energy structure of actinides and mercury isotopes

Ichikawa, Takatoshi*; Iwamoto, Akira; M$"o$ller, P.*; Sierk, A. J.*

Physical Review C, 86(2), p.024610_1 - 024610_8, 2012/08

 Times Cited Count:58 Percentile:93.9(Physics, Nuclear)

Fission-fragment mass distributions are asymmetric in fission of typical actinide nuclei for nucelon number $$A$$ in the range $$228 le A le 258$$ and proton number $$Z$$ in the range $$90 le 100$$. For somewhat lighter systems it has been observed that fission mass distributions are usually symmetric. However, a recent experiment showed that fission of $$^{198}$$Hg following electron capture on $$^{180}$$HI is asymmetric. An earlier experiment has shown fission of $$^{198}$$Hg and nearby nuclei is symmetric, but with hints of asymmetric yield distributions up to about 10 MeV above the saddle-point energy. We calculate potential-energy surfaces for a typical actinide nucleus and for 12 even isotopes in the range $$^{178}$$Hg-$$^{200}$$Hg, demonstrating the radical differences between actinide and mervury potential surfaces. We discuss these differences and how the changing potential-energy structure along the mercury isotope chain affects the observed (a)symmetry of the fission fragments. We show that the mechanism of asymmetric fission is very different in proton-rich mercury isotopes compared to the actinide region.

JAEA Reports

Study on soil decontamination and dose rate reduction effect

Iwamoto, Yosuke; Satoh, Daiki; Endo, Akira; Sakamoto, Yukio; Kureta, Masatoshi; Kugo, Teruhiko

JAEA-Technology 2011-026, 18 Pages, 2011/09

JAEA-Technology-2011-026.pdf:4.05MB
JAEA-Technology-2011-026(errata).pdf:0.24MB

The present report discusses the effect of dose rate reduction by soil decontamination in order to make a remediation strategy for contaminated environment by radionuclides discharged by the accident at the Fukushima Daiichi Nuclear Power Plant. The relation between area of soil decontamination and dose rate reduction for lands considered to be typical residences, public facilities and schools has been analyzed using the particle and heavy ion transport code PHITS, and an analytical model to assess the dose reduction rate with a simple equation was also suggested from the calculation results of PHITS. In the case of DF (Decontamination Factor) = 10 and decontamination radius = 100 m for the soil uniformly contaminated by Cs-137, the dose rate at the center of decontamination area is decreased by a factor of about five compared with the dose rate before decontamination.

Journal Articles

Evaluation of dose rate reduction in a spacecraft compartment due to additional water shield

Sato, Tatsuhiko; Niita, Koji*; Shurshakov, V. A.*; Yarmanova, E. N.*; Nikolaev, I. V.*; Iwase, Hiroshi*; Sihver, L.*; Mancusi, D.*; Endo, Akira; Matsuda, Norihiro; et al.

Cosmic Research, 49(4), p.319 - 324, 2011/08

 Times Cited Count:11 Percentile:63.69(Engineering, Aerospace)

HZE particle transport codes are the indispensable tool in the shielding design of spacecrafts. We are therefore developing a general-purpose Monte Carlo code PHITS, which can deal with the transports of all kinds of hadrons and heavy ions with energies up to 200 GeV/n in 3-dimensional phase spaces. The applicability of PHITS to space researches has been well verified by comparing the neutron spectra in spacecrafts calculated by the code with the corresponding experimental data. Recently, PHITS was employed in the estimation of radiation fields in the Russian Service Module in ISS. The results of the estimation indicate that PHITS can reproduce experimental data of the dose reduction rates due to water shielding attached on the wall of the Russian crew cabin fairly well. The details of the calculation procedures will be given in the presentation, together with the results of other applications of PHITS to the space exploration.

Journal Articles

Neutron energy spectra at 180$$^{circ}$$ from 140 MeV proton incident reactions

Iwamoto, Yosuke; Satoh, Daiki; Nakane, Yoshihiro; Nakashima, Hiroshi; Endo, Akira; Sakamoto, Yukio; Hagiwara, Masayuki*; Iwase, Hiroshi*; Yashima, Hiroshi*; Tamii, Atsushi*; et al.

Journal of the Korean Physical Society, 59(2), p.1753 - 1756, 2011/08

 Times Cited Count:2 Percentile:20.99(Physics, Multidisciplinary)

Neutron production cross sections of carbon and iron targets for 140 MeV proton at 180$$^{circ}$$ were measured at the RCNP cyclotron facility. The neutron energy spectra were obtained by using the time-of-flight technique in the energy range above 1 MeV. The results of carbon and iron targets were compared with experimental data for 113 MeV (p,xn) reactions at 150 deg by Meier et al. Our data gave good agreements with them in spite of different incident energies and angles. Calculations were performed with different intranuclear cascade models (Bertini, ISOBAR, and JQMD) implemented in the PHITS code. Calculated results with the ISOBAR and JQMD models roughly agreed with the experimental data for iron targets, although Bertini could not reproduce the high energy neutrons above 10 MeV.

Journal Articles

JENDL-4.0; A New library for innovative nuclear energy systems

Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Katakura, Junichi; Otsuka, Naohiko*

Journal of the Korean Physical Society, 59(2), p.1046 - 1051, 2011/08

 Times Cited Count:16 Percentile:68.41(Physics, Multidisciplinary)

In JENDL-4, much emphasis is placed on the improvements of FP and MA data. For achieving this, new nuclear model codes POD and CCONE were developed, since experimental data are very scarce for those nuclei. The global coupled-channel optical model parameters, which were obtained in the wide mass region, were used for the evaluation of cross sections. Thermal cross sections of actinides were determined by carefully examining available experimental data. Special care was taken for the resonance region of $$^{235}$$U in order to reproduce measured criticalities and Na-void reactivities for U fueled fast-neutron cores. As for FP, resolved resonance parameters were updated for more than 100 nuclei. The cross sections of above the resonance region were evaluated by using the POD and CCONE codes. Fission product yield data were obtained from the ENDF/B-VII.0 data with some modifications. The new library, which contains neutron data for 406 nuclei, will be made available in 2010.

JAEA Reports

Deduced soft-rotator model Hamiltonian parameters and collective properties of medium-to-heavy even-even nuclei

Kunieda, Satoshi; Chiba, Satoshi; Shibata, Keiichi; Ichihara, Akira; Iwamoto, Osamu; Iwamoto, Nobuyuki; Fukahori, Tokio; Sukhovitskij, E.*

JAEA-Research 2010-053, 59 Pages, 2011/02

JAEA-Research-2010-053.pdf:1.24MB

The soft-rotator model Hamiltonian parameters were deduced for 63 even-even medium and heavy nuclei in a mass range $$56 leq A leq 238$$. We obtained those values by the combination of the low-lying level structure and the coupled-channels proton scattering analyses. It was found that the values of the effective quadrupole and octupole deformations obtained were consistent with those derived from experimental data. Besides, the equilibrium ground-state quadrupole deformation parameters were also in reasonable accord with the theoretical mass-models results for deformed heavy nuclei. In this report, we present a complete set of the Hamiltonian parameters for each nucleus. The obtained values of the parameters often varied with the constituent neutron and/or proton numbers anomalously. On the other hand, some clear systematic trends were seen among the major Hamiltonian parameters.

Journal Articles

Experimental method for neutron elastic scattering cross-section measurement in intermediate energy region at RCNP

Satoh, Daiki; Iwamoto, Yosuke; Hagiwara, Masayuki*; Iwase, Hiroshi*; Yashima, Hiroshi*; Sanami, Toshiya*; Sato, Tatsuhiko; Endo, Akira; Sakamoto, Yukio; Nakane, Yoshihiro; et al.

Progress in Nuclear Science and Technology (Internet), 1, p.20 - 23, 2011/02

An experimental method and data processing procedure have been developed for the measurement of neutron elastic scattering cross sections in intermediate energy region above 100 MeV. The data were obtained at Research Center for Nuclear Physics (RCNP) in Osaka University by utilizing a $$^{7}$$Li(p,n) quasi-monoenergetic neutron source and Time-of-Flight (TOF) technique.

Journal Articles

JENDL-4.0; A New library for nuclear science and engineering

Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo*; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Furutaka, Kazuyoshi; Otsuka, Naohiko*; Osawa, Takaaki*; et al.

Journal of Nuclear Science and Technology, 48(1), p.1 - 30, 2011/01

 Times Cited Count:1370 Percentile:100(Nuclear Science & Technology)

The fourth version of Japanese Evaluated Nuclear Data Library has been produced. In the new library, much emphasis is placed on the improvements of fission product and minor actinoid data. Two nuclear model codes were developed to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were determined by considering recent experimental data or by the systematics of neighboring nuclei. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. The data on FP were re-evaluated, and new evaluations were performed for 30 nuclides. The data on light elements and structural materials were partly re-evaluated. The new library was released as JENDL-4.0 in May 2010.

Journal Articles

New type of asymmetric fission in proton-rich nuclei

Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.

Physical Review Letters, 105(25), p.252502_1 - 252502_5, 2010/12

 Times Cited Count:166 Percentile:97.14(Physics, Multidisciplinary)

Journal Articles

Measurement of neutron elastic scattering cross sections for carbon at 134 MeV

Satoh, Daiki; Iwamoto, Yosuke; Hagiwara, Masayuki*; Iwase, Hiroshi*; Yashima, Hiroshi*; Sato, Tatsuhiko; Endo, Akira; Sakamoto, Yukio; Nakane, Yoshihiro; Nakashima, Hiroshi; et al.

Radiation Measurements, 45(10), p.1159 - 1162, 2010/12

 Times Cited Count:1 Percentile:10.69(Nuclear Science & Technology)

Elastic neutron-scattering cross sections for carbon nucleus have been measured by using 134-MeV monoenergetic neutron beam in Research Center for Nuclear Physics (RCNP), Osaka University. The measured angles were set at 6$$^{circ}$$, 8$$^{circ}$$, and 15$$^{circ}$$ in laboratory system. The liquid organic scintillators, whose size is 12.7 cm in diameter and 12.7 cm in thickness, were mounted at each angle as neutron detector. In the off-line analysis, the events of elastic-neutron scattering were extracted on basis of the Time-of-Flight (TOF) information. The results were compared with the data measured by the groupe of U.C. Davis with a recoil proton spectrometer and the evaluations of the nuclear data libraries, JENDL/HE-2007 and ENDF/B-VII.0. Our results show a good agreement with the data of U.C. Davis. This indicates that our experimental method based on the TOF teqnique is appropriate to the measurement of elastic neutron-scattering cross section in this energy region. In addition, we exhibit that the data of ENDF/B-VII.0 represent the experimental data, but JENDL/HE-2007 underestimates about 30$${%}$$ in the forward angle region.

Journal Articles

Measurements and Monte Carlo calculations of neutron production cross-sections at 180$$^{circ}$$ for the 140 MeV proton incident reactions on carbon, iron, and gold

Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; Nakane, Yoshihiro; Tamii, Atsushi*; Iwase, Hiroshi*; Endo, Akira; Nakashima, Hiroshi; Sakamoto, Yukio; et al.

Nuclear Instruments and Methods in Physics Research A, 620(2-3), p.484 - 489, 2010/08

 Times Cited Count:6 Percentile:45.71(Instruments & Instrumentation)

The neutron production cross sections of carbon, iron, and gold targets with 140 MeV protons at 180$$^{circ}$$ were measured at the RCNP cyclotron facility. The time-of-flight technique was used to obtain the neutron energy spectra in the energy range above 1 MeV. The carbon and iron target results were compared with the experimental data from 113 MeV (p,xn) reactions at 150$$^{circ}$$ reported by Meier et al. Our data agreed well with them in spite of different incident energies and angles. Calculations were then performed using different intra-nuclear cascade models (Bertini, ISOBAR, and JQMD) implemented with PHITS code. The results calculated using the ISOBAR and JQMD models roughly agreed with the experimental iron and gold target data, but the Bertini could not reproduce the high energy neutrons above 10 MeV.

109 (Records 1-20 displayed on this page)