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Journal Articles

Unified description of the fission probability for highly excited nuclei

Iwamoto, Hiroki; Meigo, Shinichiro

Journal of Nuclear Science and Technology, 56(2), p.160 - 171, 2019/02

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

We present a new model to describe the fission probability of the high-energy fission model, as deduced from the intranuclear cascade calculation with the Intra-Nuclear Cascade model of Li$`{e}$ge (INCL) version 4.6 and Prokofiev's phenomenological systematics of the proton-induced fission cross sections. This model is implemented in the de-excitation model of the Generalized Evaporation Model (GEM), and applied to Monte Carlo spallation reaction simulation using the Particle and Heavy Ion Transport code System (PHITS). Comparing with experimental data for subactinide nuclei shows that this model can provide a unified prediction of the proton-, neutron-, and deuteron-induced fission cross sections with markedly improved accuracy. The calculated fission fragments tend to shift to higher mass numbers. To account for the isotopic distributions of fission fragments within the framework of a coupled INCL/GEM, modification of INCL is required, especially for description of the highly-excited states of residual nuclei.

Journal Articles

Measurement of activation cross sections of aluminum for protons with energies between 0.4 GeV and 3.0 GeV at J-PARC

Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Hiroki

Progress in Nuclear Science and Technology (Internet), 6, p.171 - 174, 2019/01

Activation cross sections of various materials are strongly required for the improvement of the accuracy of nuclear design and the reduction of the construction costs for spallation neutron sources and transmutation systems. Activation cross sections have been measured in several facilities. However, they have low accuracy and precision. Especially, there are merely experimental data with 3 GeV protons which are used for spallation neutron source (MLF) in J-PARC, the experimental data is required for the improvement of the target materials. Thus, we measured cross sections of tungsten, gold, indium, and beryllium with 0.4 GeV to 3.0 GeV protons. Moreover, ones of aluminium that are set with materials were also measured for a variation of this experiment. It was found that more accurate data than current ones would be measured by using precise beam controls and highly accurate beam monitoring. We compared the experimental data, the evaluated data (JENDL-HE/2007), and the calculations with several intra-nuclear cascade models by PHITS code. Although the experimental data agreed with JENDL-HE/2007, the calculations underestimated about 40%. This could come from the evaporation model (GEM) being included in PHITS code. We found that the calculations agreed with the experimental data by upgrading PHITS code. The cross sections for the other materials have been analysed so far.

Journal Articles

Sensitivity and uncertainty analysis of $$beta_{rm eff}$$ for MYRRHA using a Monte Carlo technique

Iwamoto, Hiroki; Stankovskiy, A.*; Fiorito, L.*; Van den Eynde, G.*

European Physical Journal; Nuclear Sciences & Technologies (Internet), 4, p.42_1 - 42_7, 2018/11

This paper presents a nuclear data sensitivity and uncertainty analysis of the effective delayed neutron fraction $$beta_{rm eff}$$ for critical and subcritical cores of the MYRRHA reactor using the continuous-energy Monte Carlo transport code MCNP. The $$beta_{rm eff}$$ sensitivities are calculated by the modified $$k$$-ratio method proposed by Chiba. Comparing the $$beta_{rm eff}$$ sensitivities obtained with different scaling factors $$a$$ introduced by Chiba shows that a value of $$a=20$$ is the most suitable for the uncertainty quantification of $$beta_{rm eff}$$. Using the calculated $$beta_{rm eff}$$ sensitivities and the JENDL-4.0u covariance data, the $$beta_{rm eff}$$ uncertainties for the critical and subcritical cores are determined to be 2.2 $$pm$$ 0.2% and 2.0 $$pm$$ 0.2%, respectively, which are dominated by delayed neutron yield of $$^{239}$$Pu and $$^{238}$$U.

Journal Articles

High-energy nuclear data uncertainties propagated to MYRRHA safety parameters

Stankovskiy, A.*; Iwamoto, Hiroki; $c{C}$elik, Y.*; Van den Eynde, G.*

Annals of Nuclear Energy, 120, p.207 - 218, 2018/10

 Times Cited Count:2 Percentile:34.36(Nuclear Science & Technology)

Propagation of high-energy (above 20-MeV) nuclear data uncertainties on the safety related neutronic responses in accelerator driven systems has been assessed. The total core power and production of radionuclides contributing to radiation source terms were focused on. The article features a method based on the Monte Carlo sampling of random nuclear data files from the covariance matrices generated from the sets of reaction cross sections obtained with model calculations of high-energy particle interactions with matter or picked up from already existing nuclear data libraries. It has been demonstrated that nuclear data uncertainties do not need to be propagated through particle transport calculations to obtain uncertainties on the responses. This advantage allowed to investigate the convergence of the sample average to the best estimate. The number of random nuclear data file sets needed to obtain reliable uncertainty on the total core power is around 300 that results in the uncertainty of 14%. The uncertainties on the concentrations of nuclides most important for the safety assessment that are accumulated in lead-bismuth eutectic during irradiation, range from 5 to 60%. Concentrations of some nuclides exemplified by Tritium converge much slower than neutron multiplicities so that several thousands of samples are needed to ensure reliable uncertainty estimates.

Journal Articles

Measurement of displacement cross sections of aluminum and copper at 5 K by using 200 MeV protons

Iwamoto, Yosuke; Yoshida, Makoto*; Yoshiie, Toshimasa*; Satoh, Daiki; Yashima, Hiroshi*; Matsuda, Hiroki; Meigo, Shinichiro; Shima, Tatsushi*

Journal of Nuclear Materials, 508, p.195 - 202, 2018/09

 Times Cited Count:2 Percentile:34.36(Materials Science, Multidisciplinary)

To validate the displacement damage model in radiation transport codes used for the estimation of radiation damages at accelerator facilities, we measured electrical resistance increase of aluminum and copper induced by radiation defects under the cryogenic 200 MeV proton irradiation. The irradiation device had the structure to cool two irradiation samples at same time using thermal conductance. The aluminum and copper wire with 250 $$mu$$m diameter was sandwiched between two AlN plates with excellent thermal conductivity and electrical insulation. As a result, temperature of irradiation samples was kept at below 5 K under proton irradiation with beam intensity below 3 nA. The experimental displacement cross section agreed with calculated results with defect production efficiency.

Journal Articles

Proton-induced activation cross section measurement for aluminum with proton energy range from 0.4 to 3 GeV at J-PARC

Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Hiroki

Journal of Nuclear Science and Technology, 55(8), p.955 - 961, 2018/08

 Times Cited Count:1 Percentile:59.08(Nuclear Science & Technology)

We have started an experimental program to measure activation cross sections systematically in the proton-induced spallation reaction in structural materials commonly used in high-intensity proton accelerator-based facilities, such as Japan Proton Accelerator Research Complex (J-PARC). As the first step of the program, aluminum (Al) was chosen to verify the adequacy of the measurement technique implemented in a J-PARC proton beam environment because data of Al have been relatively well studied both by experimental measurement and simulation. Activation cross sections of $$^{7}$$Be, $$^{22}$$Na, and $$^{24}$$Na in Al were measured at proton energy points from 0.4, 1.3, 2.2 to 3.0 GeV, which could be delivered smoothly from the synchrotron. The validity of experimental data has been verified by introducing an effective proton numbers determination procedure. We compared the measured data with existing experimental data, the evaluated data (JENDL-HE/2007), and the calculations with several intra-nuclear cascade models by the Particle and Heavy Ion Transport code System (PHITS) code. Although the experimental data agreed with JENDL-HE/2007, the calculations underestimated about 40%. This could come from the evaporation model (generalized evaporation model) being implemented in the PHITS code. We found that the calculations agreed with the experimental data by an upgraded PHITS code.

Journal Articles

Design study of beam window for accelerator-driven system with subcriticality adjustment rod

Sugawara, Takanori; Eguchi, Yuta; Obayashi, Hironari; Iwamoto, Hiroki; Matsuda, Hiroki; Tsujimoto, Kazufumi

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 10 Pages, 2018/07

A new beam window concept for accelerator-driven system (ADS) is investigated by changing the design condition. The most important factor for the beam window design is the proton beam current. The design condition will be mitigated if the proton beam current will be reduced. To reduce the proton beam current, a subcriticality adjustment rod (SAR) which was a B$$_4$$C control rod was employed and neutronics calculations were performed by ADS3D code. The results of the neutronics calculation indicated that the proton beam current was reduced from 20mA to 13.5mA by the installation of SARs. Based on the mitigated calculation condition, the investigation of the beam window was performed by the couple analyses of the particle transport, the thermal hydraulics and the structural analysis. Through these coupled analyses, more feasible beam window concept which was the hemispherical shape, the outer diameter = 470mm, the thickness at the top = 3.5mm and factor of safety =9 was presented.

Journal Articles

Radiation damage calculation in PHITS and benchmarking experiment for cryogenic-sample high-energy proton irradiation

Iwamoto, Yosuke; Matsuda, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Nakamoto, Tatsushi*; Yoshida, Makoto*; Ishi, Yoshihiro*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Yashima, Hiroshi*; et al.

Proceedings of 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2018) (Internet), p.116 - 121, 2018/07

The radiation damage model in the radiation transport code PHITS has been developed to calculate the basic data of the radiation damage including the energy of the target Primary Knock on Atom (PKA). For the high-energy proton incident reactions, a target PKA created by the secondary particles was more dominant than a target PKA created by the projectile. To validate the radiation damage model in metals irradiated by $$>$$100 MeV protons, we developed a proton irradiation device with a Gifford-McMahon cryocooler to cryogenically cool wire samples. By using this device, the defect-induced electrical resistivity changes related to the DPA cross section of copper and aluminum were measured under irradiation with 125 and 200 MeV protons at cryogenic temperature. A comparison of the experimental data with the calculated results indicates that the DPA cross section with defect production efficiencies provide better quantitative descriptions.

Journal Articles

Research and development activities for accelerator-driven system in JAEA

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:5 Percentile:8.08(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.

Journal Articles

Measurement of activation cross sections of the target and the proton beam window materials at J-PARC

Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Hiroki

Journal of Physics; Conference Series, 1021(1), p.012016_1 - 012016_4, 2018/06

 Times Cited Count:0 Percentile:100

For the improvement of the accuracy of nuclear design for spallation neutron sources and transmutation systems, nuclear reaction cross sections are required. Considering decommissioning of the accelerator facilities, accurate cross sections are mandatory. The activation cross sections have been measured in several facilities. However, they have low accuracy and precision. Especially, since there is almost no data for 3 GeV protons which are used for spallation neutron source (JSNS) in J-PARC, the experimental data is required for the improvement of the target materials.For the sake of the forthcoming full-time measurement of the activation cross sections for various nuclei, we measured the ones of aluminium with 0.4, 1.3, 2.2, and 3.0 GeV protons as the test purpose. It was found that more accurate data than current ones would be measured by using precise beam controls and highly accurate beam monitoring. We compared the experimental data, the evaluated data (JENDL-HE/2007), and the calculations with several intra-nuclear cascade models by PHITS code. Although the experimental data agreed with JENDL-HE/2007, the calculations underestimated about 40%. This could come from the evaporation model (GEM) being included in PHITS code. We found that the calculations agreed with the experimental data by upgrading PHITS code.

Journal Articles

The Measurements of neutron energy spectrum at 180 degrees with the mercury target at J-PARC

Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Hiroki

Journal of Physics; Conference Series, 1021(1), p.012017_1 - 012017_4, 2018/06

 Times Cited Count:0 Percentile:100

Spallation neutron at 180 degrees is of important for an evaluation of radiation protection for ADS (Accelerator-Driven System) and the nuclear physics. It was, however, quite difficult to measure it. We measured the energy spectrum of spallation neutron at 180 degrees at the proton transport beam line (3NBT) to MLF (Materials and Life Science Experimental Facility) on J-PARC by the NE213 liquid scintillator. The irradiated proton energy was 3 GeV, and the intensity was 1$$times$$10$$^{10}$$ protons above. The neutron energy was determined by Time-Of-Flight method with n-gamma discrimination. We also simulated the energy spectrum by using PHITS code and compared with measured spectrum. In this paper, the overview of the experiment and the results are described.

Journal Articles

Target test facility for ADS and cross-section experiment in J-PARC

Meigo, Shinichiro; Iwamoto, Hiroki; Matsuda, Hiroki; Takei, Hayanori

Journal of Physics; Conference Series, 1021(1), p.012072_1 - 012072_4, 2018/06

 Times Cited Count:0 Percentile:100

no abstracts in English

Journal Articles

Shielding analysis of Transmutation Experimental Facility

Iwamoto, Hiroki; Matsuda, Hiroki; Meigo, Shinichiro

Journal of Physics; Conference Series, 1021(1), p.012049_1 - 012049_4, 2018/06

 Times Cited Count:0 Percentile:100

To promote research, development, and demonstration of elemental technologies for accelerator-driven systems (ADS), the Japan Atomic Energy Agency (JAEA) is planning to construct Transmutation Experimental Facility (TEF) at J-PARC. At ADS Target Test Facility (TEF-T), 250-kW H$$^{-}$$ beams accelerated by the 400-MeVLINAC will be derived to a lead-bismuth eutectic (LBE) target for the material examinations aimed for the ADS. The TEF-T will operate as a spallation neutron source especially for research and development of semiconductor by using high-energy neutrons. For the license of this facility, the shielding design is important because unnecessary shield increase drastically the cost of construction. In this study, shielding analysis was carried out for whole structure of the TEF in detail toward the construction. To reduce the neutron flux and cost efficiently, an iron and an ordinary concrete will be employed as shield. The detailed structure for the shielding was determined by the PHITS code based on the intra-nuclear cascade with statistical decay model. It was found that the backward neutrons from the target are important to reduce the cost of the shielding so that we have plan to measure by using J-PARC accelerator. Shielding including the beam tunnel, hot-cell to maintain the LBE target, beam dumps for beam commissioning, and a neutron beam port for multipurpose utilization were also determined. This paper presents the results of the shielding analysis for these components and the shielding structure of the whole TEF.

Journal Articles

Measurement of displacement cross-section for structural materials in High-Power Proton Accelerator Facility

Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Iwamoto, Hiroki; Hasegawa, Shoichi; Maekawa, Fujio; Yoshida, Makoto*; Ishida, Taku*; Makimura, Shunsuke*; Nakamoto, Tatsushi*

Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.499 - 501, 2018/06

no abstracts in English

Journal Articles

Monte Carlo uncertainty quantification of the effective delayed neutron fraction

Iwamoto, Hiroki; Stankovskiy, A.*; Fiorito, L.*; Van den Eynde, G.*

Journal of Nuclear Science and Technology, 55(5), p.539 - 547, 2018/05

 Times Cited Count:4 Percentile:12.45(Nuclear Science & Technology)

The applicability of Monte Carlo techniques, namely the Monte Carlo sensitivity method and the random-sampling method, for uncertainty quantification of the effective delayed neutron fraction $$beta_{rm eff}$$ is investigated using the continuous-energy Monte Carlo transport code, MCNP, from the perspective of statistical convergence issues. This study focuses on the nuclear data as one of the major sources of $$beta_{rm eff}$$ uncertainty. For validation of the calculated $$beta_{rm eff}$$, a critical configuration of the VENUS-F zero-power reactor was used. It is demonstrated that Chiba's modified $$k$$-ratio method is superior to Bretscher's prompt $$k$$-ratio method in terms of reducing the statistical uncertainty in calculating not only $$beta_{rm eff}$$ but also its sensitivities and the uncertainty due to nuclear data. From this result and a comparison of uncertainties obtained by the Monte Carlo sensitivity method and the random-sampling method, it is shown that the Monte Carlo sensitivity method using Chiba's modified $$k$$-ratio method is the most practical for uncertainty quantification of $$beta_{rm eff}$$. Finally, total $$beta_{rm eff}$$ uncertainty due to nuclear data for the VENUS-F critical configuration is determined to be approximately 2.7% with JENDL-4.0u, which is dominated by the delayed neutron yield of $$^{235}$$U.

Journal Articles

Conceptual design study of beam window for accelerator-driven system with subcriticality adjustment rod

Sugawara, Takanori; Eguchi, Yuta; Obayashi, Hironari; Iwamoto, Hiroki; Tsujimoto, Kazufumi

Nuclear Engineering and Design, 331, p.11 - 23, 2018/05

 Times Cited Count:2 Percentile:34.36(Nuclear Science & Technology)

This study aims to perform the coupled analysis for the feasible beam window concept. To mitigate the design condition, namely to reduce the necessary proton beam current, subcriticality adjustment rod (SAR) was installed to the ADS core. The burnup analysis was performed for the ADS core with SAR and the results indicated that the maximum proton beam current during the burnup cycle was reduced from 20 to 13.5 mA. Based on the burnup analysis result, the coupled analysis; particle transport, thermal hydraulics and structural analyses, was performed. As the final result, the most robust beam window design; the hemisphere shape, the outer radius = 235 mm, the thickness at the top of the beam window = 3.5 mm and the factor of safety for the buckling = 9.0, was presented. The buckling pressure was 2.2 times larger than the previous one and more feasible beam window concept was presented through this study.

Journal Articles

Cross section measurement in J-PARC for neutronics of the ADS

Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Hiroki

Proceedings of 13th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '17) (Internet), p.396 - 402, 2018/05

no abstracts in English

Journal Articles

Reaction rate analyses of accelerator-driven system experiments with 100 MeV protons at Kyoto University Critical Assembly

Pyeon, C. H.*; Vu, T. M.*; Yamanaka, Masao*; Sugawara, Takanori; Iwamoto, Hiroki; Nishihara, Kenji; Kim, S. H.*; Takahashi, Yoshiyuki*; Nakajima, Ken*; Tsujimoto, Kazufumi

Journal of Nuclear Science and Technology, 55(2), p.190 - 198, 2018/02

 Times Cited Count:9 Percentile:2.75(Nuclear Science & Technology)

At the Kyoto University Critical Assembly, a series of reaction rate experiments is conducted on the accelerator-driven system (ADS) with spallation neutrons generated by the combined use of 100 MeV protons and a lead and bismuth target in the subcritical state. The reaction rates are measured by the foil activation method to obtain neutron spectrum information on ADS. Numerical calculations are performed with MCNP6.1 and JENDL/HE-2007 for high-energy protons and spallation process, JENDL-4.0 for transport and JENDL/D-99 for reaction rates. The reaction rates depend on subcriticality is revealed by the accuracy of the C/E (calculation/experiment) values. Nonetheless, the accuracy of the reaction rates at high-energy thresholds remains an important issue in the fixed-source calculations.

JAEA Reports

Assessment of lead-bismuth-eutectic leak at ADS Target Test Facility in Transmutation Experimental Facility of J-PARC

Iwamoto, Hiroki; Maekawa, Fujio; Matsuda, Hiroki; Meigo, Shinichiro

JAEA-Technology 2017-029, 39 Pages, 2018/01

JAEA-Technology-2017-029.pdf:2.68MB

Under an assumption that an incident of lead-bismuth eutectic (LBE) leak from an LBE circulation system occurred during a 250-kW beam operation, an estimation of radiation dose at the site boundary for the ADS Target Test Facility (TEF-T) in Transmutation Experimental Facility (TEF) of J-PARC was conducted using various conservative assumptions. As a result, the radiation dose at the site boundary was estimated to be about 660 $$mu$$Sv, which were dominated by mercury, noble gas, and iodine produced as spallation products from the LBE. Even though the incident scenario was made conservatively, it was shown that the estimated total dose was lower than the annual radiation dose due to natural sources, and the TEF-T has sufficient safety margin for the leak of radioactivity.

Journal Articles

Theoretical model analysis of $$(d,xn)$$ reactions on $$^7$$Li at 25, 40, and 102 MeV

Sadamatsu, Hiroki*; Nakayama, Shinsuke; Watanabe, Yukinobu*; Iwamoto, Osamu; Ogata, Kazuyuki*

JAEA-Conf 2017-001, p.135 - 140, 2018/01

In recent years, the demand for intense neutron sources has been increasing in various applications such as nuclear transmutation of high-level radioactive waste and medical radioisotopes production. Deuteron accelerator-based neutron sources are promised as one of the candidates. Therefore, we have developed a code system dedicated for the deuteron-induced reactions, called DEURACS. In the present work, we focus on deuteron-induced neutron production from $$^7$$Li target. The calculated double differential cross sections for $$(d,xn)$$ reactions at incident energies of 25, 40, and 102 MeV are compared with the measured ones, and the applicability of DEURACS is discussed.

126 (Records 1-20 displayed on this page)