Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Oizumi, Akito; Fukushima, Masahiro; Tsujimoto, Kazufumi; Yamanaka, Masao*; Sano, Tadafumi*; Pyeon, C. H.*
KURRI Progress Report 2017, P. 50, 2018/08
In the nuclear transmutation system such as ADS, the nuclear data validation of MA is required to reduce the uncertainty caused by the nuclear data of MA. This study aims to measure the reaction rates of Neptunium-237 (
Np) and Americium-241 (
Am) using the nuclear spallation neutron source in the KUCA for 3 hours. The observed distributions of pulse-height of Np and Am fission reactions were significantly different from the ones generally observed in critical and pulsed neutron source (PNS) experiments because of the influence of the 
-ray generated by the nuclear spallation reaction. On the other hand, the capture reaction rate of Np was measured in this experiment. The capture reaction rate of the critical experiment which was available to be measured the fission reaction rate of Np and Am was almost 8 times larger than that of this experiment. Consequently, reducing the influence of the generated by the nuclear spallation reaction and extending the duration of the irradiation to 24 or more hours would be necessary for detecting signals of fission reactions under the spallation neutron source.
Sugawara, Takanori; Takei, Hayanori; Iwamoto, Hiroki; Oizumi, Akito; Nishihara, Kenji; Tsujimoto, Kazufumi
Progress in Nuclear Energy, 106, p.27 - 33, 2018/07
Times Cited Count：1 Percentile：100(Nuclear Science & Technology)The Japan Atomic Energy Agency (JAEA) has investigated an accelerator-driven system (ADS) to transmute minor actinides which will be partitioned from the high level waste. There are various inherent issues for the research and development on the ADS. The recent two activities to realize a feasible and reliable ADS concept are introduced in this paper. For the feasibility, the design of a beam window which is a boundary of the accelerator and the subcritical core, is one of the most important issues. To mitigate the design condition of the beam window, namely to reduce the proton beam current, the subcritical core concept with subcriticality adjustment rods were investigated. For the reliability, the beam-trip is the inherent and serious issue for the ADS design because it induces rapid temperature change to coolant and structures in the subcritical core. To improve the beam-trip frequencies, a double-accelerator concept was proposed and its beam-trip frequency was estimated.
Fukushima, Masahiro; Goda, J.*; Bounds, J.*; Cutler, T.*; Grove, T.*; Hutchinson, J.*; James, M.*; McKenzie, G.*; Sanchez, R.*; Oizumi, Akito; et al.
Nuclear Science and Engineering, 189, p.93 - 99, 2018/01
Times Cited Count：1 Percentile：38.14(Nuclear Science & Technology)To validate lead (Pb) nuclear cross sections, a series of integral experiments to measure lead void reactivity worths was conducted in a high-enriched uranium (HEU)/Pb system and a low enriched uranium (LEU)/Pb system using the Comet Critical Assembly at NCERC. The critical experiments were designed to provide complementary data sets having different sensitivities to scattering cross sections of lead. The larger amount of the 
U present in the LEU/Pb core increases the neutron importance above 1 MeV compared with the HEU/Pb core. Since removal of lead from the core shifts the neutron spectrum to the higher energy region, positive lead void reactivity worths were observed in the LEU/Pb core while negative values were observed in the HEU/Pb core. Experimental analyses for the lead void reactivity worths were performed with the Monte Carlo calculation code MCNP6.1 together with nuclear data libraries, JENDL 4.0 and ENDF/B VII.1. The calculation values were found to overestimate the experimental ones for the HEU/Pb core while being consistent for the LEU/Pb core.
Oizumi, Akito; Sugawara, Takanori; Iwamoto, Hiroki; Nishihara, Kenji; Tsujimoto, Kazufumi
NEA/NSC/R(2017)2, p.152 - 160, 2017/06
Sugawara, Takanori; Nishihara, Kenji; Iwamoto, Hiroki; Oizumi, Akito; Tsujimoto, Kazufumi
Journal of Nuclear Science and Technology, 53(12), p.2018 - 2027, 2016/12
Times Cited Count：5 Percentile：23.48(Nuclear Science & Technology)In order to perform the parametric survey for an Accelerator-Driven System (ADS) core with the subcriticality adjustment mechanism, a new calculation code system, ADS3D, was developed on MARBLE which is a comprehensive and versatile framework for reactor analysis. ADS3D can calculate the transportation of neutrons, the burn-up performance and the fuel exchange by deterministic method in three-dimensional calculation models. The application of ADS3D was also presented for the neutronics design of the ADS core with the control rod. Through the neutronics calculation, it was shown that the maximum proton beam current was decreased from 20.5mA to 11.6mA by the installation of control rods.
Sugawara, Takanori; Nishihara, Kenji; Takei, Hayanori; Iwamoto, Hiroki; Oizumi, Akito; Sasa, Toshinobu; Tsujimoto, Kazufumi
Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.648 - 656, 2015/09
The JAEA has investigated an accelerator-driven system (ADS) to transmute minor actinides which will be partitioned from the high level waste. There are various inherent issues for the research and development on the ADS. This study introduces the current two activities to get a feasible and reliable ADS concept. For the feasibility, the beam window design is one of the most important issues. To mitigate the design condition of the beam window, namely to reduce the proton beam current, the subcritical core concepts with subcriticality adjustment mechanism were investigated. As the result, the proton beam current reduced from 20mA to 10mA by the installation of the control rods. For the reliability, the two accelerators concept was proposed and the beam trip frequency was estimated by the J-PARC LINAC data and Monte-Carlo method. Through these investigations, it was confirmed that the two accelerators concept was useful to realize reliable accelerator operation for the ADS.
Oizumi, Akito; Jin, Tomoyuki*; Ishikawa, Makoto; Kugo, Teruhiko
Annals of Nuclear Energy, 81, p.117 - 124, 2015/07
Percentile：100(Nuclear Science & Technology)The uncertainty associated with physical quantities, such as nuclear data, needs to be quantitatively analyzed. The present paper illustrates an analysis methodology to investigate the physical mechanisms of burnup actinide composition with nuclear-data sensitivity based on the generalized depletion perturbation theory. The target in this paper is the MOX fuel of the light water reactor. We start with the discussion of the basic physical mechanisms for burnup actinide compositions using the reaction-rate flow chart on the burnup chain. After that, the physical mechanisms of the productions of 
Cm and Pu are analyzed in detail with burnup sensitivity calculation. Conclusively, we can identify the source of actinide productions and evaluate the indirect influence of the nuclear reactions if the physical mechanisms of burnup actinide composition are analyzed using the reaction-rate flow chart on the burnup chain and burnup sensitivity calculation. Finally, we demonstrate the usefulness of the burnup sensitivity coefficients in an application to determine the priority of accuracy improvement in nuclear data in combination with the covariance of the nuclear data. In addition, the target actinides and reactions are categorized into patterns according to a sensitivity trend.
Fukushima, Masahiro; Oizumi, Akito; Iwamoto, Hiroki; Kitamura, Yasunori
JAEA-Data/Code 2014-030, 50 Pages, 2015/03
JAEA-Data-Code-2014-030.pdf:10.34MB
In the IX-th experimental series in 1980's at the fast critical assembly (FCA) facility, central fission rate ratios for TRU such as Np, Pu, 
Pu, Am, 
Am and Cm to 
Pu were measured in the seven uranium-fueled assemblies with systematically changed neutron spectra. In the present report, benchmark problems with respect to central fission rate ratios were established for the assessment of the TRU's fission cross sections. We reported the sample calculation results on the benchmark problems by using JENDL-4.0.
Sugawara, Takanori; Oizumi, Akito; Kitamura, Yasunori; Iwamoto, Hiroki; Yagi, Takahiro*; Pyeon, C. H.*
KURRI Progress Report 2013, 1 Pages, 2014/10
The Japan Atomic Energy Agency (JAEA) has investigated the accelerator-driven system (ADS) to transmute minor actinides discharged from nuclear power plants. The ADS investigated by JAEA is a lead bismuth eutectic (LBE) cooled-tank-type ADS. It has been known that there was a major upgrade for the cross section data of lead isotopes from JENDL-3.3 to JENDL-4.0. Due to this upgrade, the value of 
of the core was significantly changed, from 0.97 calculated by JENDL-3.3 to 1.00 calculated by JENDL-4.0. The difference was mainly caused by the cross section data of the lead isotopes from JENDL-3.3 to JENDL-4.0. This study aims to measure sample worth reactivity from aluminum plates to lead or LBE ones to validate the nuclear data of lead and bismuth isotopes.
Kihara, Shinji; Amazawa, Hiroya; Sakai, Akihiro; Nakata, Hisakazu; Kugo, Teruhiko; Matsuda, Norihiro; Oizumi, Akito; Sasamoto, Hiroshi; Mitsui, Seiichiro; Miyahara, Kaname
JAEA-Research 2013-033, 320 Pages, 2014/07
JAEA-Research-2013-033.pdf:119.17MB
JAEA performed decontamination experiments at two test sites that combined a range of buildings and different types of land use, located in Date and Minami Soma municipalities as field pilot projects in order to accumulate knowledge and data for full-scale decontamination activities performed by local governments. In the pilot projects, we established its plan using practical decontamination methods that can be easily implemented, according to decontamination targets (e.g., forests, agricultural land, residential house and roads) at each site. As a result of the decontamination, the average air dose rates were reduced to approximately one half of the values before decontamination.
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：3 Percentile：61.51(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.
Oizumi, Akito; Jin, Tomoyuki*; Yokoyama, Kenji; Ishikawa, Makoto; Kugo, Teruhiko
JAEA-Data/Code 2013-019, 278 Pages, 2014/02
JAEA-Data-Code-2013-019.pdf:13.33MB
JAEA-Data-Code-2013-019-appendix-(CD-ROM).zip:114.27MB
In design work for nuclear fuel cycle plants, decommissioning facilities and light water reactors (LWRs), it has been feasible to quantitatively evaluate the uncertainty of fuel burnup characteristics with identifying error sources arising from the analytical modeling or the related physical property such as nuclear data. Owing to the recent improvement of sensitivity analysis method and enhancement of computer capability, this new evaluation technology would be a promising strategy against the current demand for quality assurance, verification & validation (V&V) and accountability. The present report summarizes nuclear-data sensitivity of atomic number densities after burnup for the LWR fuels of UO
and MOX in PWR and BWR. The analysis method is based on the generalized perturbation theory with JENDL-4.0 and a multi-purpose reactor analysis code MARBLE. The present study focuses on 35 fission products and 18 actinides. Sensitivities are calculated with respect to multigroup cross sections, half-lives and fission yields. Electronic files of the sensitivities are stored in a compact disk as a database. Important trends of the sensitivities are presented and their physical mechanisms are discussed. By incorporating the sensitivities with nuclear data covariance and post irradiation examination data, it would be possible to meet the demand for V&V and to break down the uncertainty due to nuclear data into dominant error sources. Thus, the sensitivities can be used to suggest the needs for nuclear data measurements and to extract those for reactor physics experiments in order to make the strategic deliberation of design rationalization.
Oizumi, Akito; Akie, Hiroshi; Iwamoto, Nobuyuki; Kugo, Teruhiko
Journal of Nuclear Science and Technology, 51(1), p.77 - 90, 2014/01
Times Cited Count：1 Percentile：85.45(Nuclear Science & Technology)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.
Cm production in spent fuel of light water reactor by using burnup sensitivity analysisOizumi, Akito; Yokoyama, Kenji; Ishikawa, Makoto; Kugo, Teruhiko
JAEA-Conf 2013-002, p.59 - 64, 2013/10
Z nucleus, 
Ar and high-spin states in A = 30 
40 nucleiIdeguchi, Eiji*; Ota, Shinsuke*; Morikawa, Tsuneyasu*; Oshima, Masumi; Koizumi, Mitsuo; Toh, Yosuke; Kimura, Atsushi; Harada, Hideo; Furutaka, Kazuyoshi; Nakamura, Shoji; et al.
Progress of Theoretical Physics Supplement, (196), p.427 - 432, 2012/10
Satoh, Daiki; Oizumi, Akito; Matsuda, Norihiro; Kojima, Kensuke; Kugo, Teruhiko; Sakamoto, Yukio*; Endo, Akira; Okajima, Shigeaki
RIST News, (53), p.12 - 23, 2012/09
Decontamination planning based on a computer simulation code CDE is discussed in this paper. Large amount of radionuclides had been discharged to environment in the accident of the Tokyo Electronic Power Corporation Fukushima Dai-ichi Nuclear Power Plant. CDE has been developed to support planning the decontamination. From the present study, it is validated that the computer simulation is very useful to predict the effect of the scenario before actions, and to plan the decontamination.
Satoh, Daiki; Kojima, Kensuke; Oizumi, Akito; Matsuda, Norihiro; Kugo, Teruhiko; Sakamoto, Yukio*; Endo, Akira; Okajima, Shigeaki
JAEA-Research 2012-020, 97 Pages, 2012/08
JAEA-Research-2012-020.pdf:7.32MB
A computer software, named CDE (Calculation system for Decontamination Effect), has been developed to support planning the decontamination. CDE calculates the dose rates before the decontamination by using a database of dose contributions by radioactive cesium. The decontamination factor is utilized in the prediction of the dose rates after the decontamination, and dose rate reduction factor is evaluated to express the decontamination effect. The results are visualized on the image of a target zone with color map. In this paper, the overview of the software and the dose calculation method are reported. The comparison with the calculation results by a three-dimensional radiation transport code PHITS is also presented. In addition, the source code of the dose calculation program and user's manual of CDE are attached as appendices.
Chiba, Go; Okumura, Keisuke; Oizumi, Akito*; Saito, Masaki*
Journal of Nuclear Science and Technology, 47(7), p.652 - 660, 2010/07
In order to specify important nuclear data for accurate prediction of fission product concentrations(FPC), we extensively evaluate sensitivities of FPC to nuclear data with the depletion perturbation theory. The target fission products are twelve important ones for the burnup credit. The present study successfully specifies the important nuclear data both in a UO
cell and in a MOX cell. While the obtained sensitivities are mostly similar to each other between the UO and MOX cells, large differences are observed in some cases, such as the Gd-155 concentration. It is clearly shown that such differences between the UO and MOX cells come from differences in cumulative fission yields between U-235 and Pu-239 and differences in neutron flux energy spectra.
nucleus ArIdeguchi, Eiji*; Ota, Shinsuke*; Morikawa, Tsuneyasu*; Oshima, Masumi; Koizumi, Mitsuo; Toh, Yosuke; Kimura, Atsushi; Harada, Hideo; Furutaka, Kazuyoshi; Nakamura, Shoji; et al.
Physics Letters B, 686(1), p.18 - 22, 2010/03
Times Cited Count：26 Percentile：13.74(Astronomy & Astrophysics)A rotational band with five -ray transitions ranging from 2
to 12 states was identified in Ar. The deduced transition quadrupole moment of 1.45 
0.15 eb indicates that the band has a superdeformed shape. The nature of the band is revealed by cranked Hartee Fock Bogoliubov calculations and a multiparticle-multihole configuration is assigned to the band.
