Characteristics of temporal variability of long-duration bursts of high-energy radiation associated with thunderclouds on the Tibetan plateau

Tsuchiya, Harufumi; Hibino, Kinya*; Kawata, Kazumasa*; Onishi, Munehiro*; Takita, Masato*; Munakata, Kazuoki*; Kato, Chihiro*; Shimoda, Susumu*; Shi, Q.*; Wang, S.*; et al.

Progress of Earth and Planetary Science (Internet), 11, p.26_1 - 26_14, 2024/05

https://doi.org/10.1186/s40645-024-00625-y

Development of a test method for electrochemical measurements of stainless steel in nitric acid solution containing neptunium-237 under gamma-ray irradiation

Yamashita, Naoki; Irisawa, Eriko; Kato, Chiaki; Sano, Naruto; Tagami, Susumu

JAEA-Technology 2022-035, 29 Pages, 2023/03

JAEA-Technology-2022-035.pdf:2.54MB

In the treatment process of the current commercial reprocessing plant (Rokkasho Reprocessing Plant), the high-level liquid waste concentrator is the equipment that treats the most corrosive solution. In the high-level liquid waste concentrator, the extracted liquid waste after separation of uranium and plutonium is heated, concentrated, and reduced in volume. Therefore, the amount of gamma- rays emitted from fission products and the concentration of corrosive metal ion species such as neptunium-237 (Np) are the highest in the reprocessing process, and the amount of corrosion in the high-level liquid waste concentrate canner is expected to be large. In this study, in order to clarify the effect of gamma-rays on the corrosion reaction of stainless steel in nitric acid solutions containing Np from the electrochemical viewpoint, the corrosion test apparatus for heat transfer surfaces in an airtight concrete cell at the Waste Safety TEsting Facility (WASTEF) of Nuclear Science Research Institute was modified to enable electrochemical measurements under gamma-ray irradiation. The effect of gamma-rays on the corrosion reaction taking place on the stainless steel surface was discussed from the electrochemical test results obtained. As a result, changes in the immersion potentials of stainless steel and the polarization curves due to chemical species caused by radiolysis of gamma-ray irradiation were confirmed.

Simulation of discharge in insulating gas from initial partial discharge to growth of a stepped leader using the percolation model

Sasaki, Akira; Kato, Susumu*; Takahashi, Eiichi*; Kishimoto, Yasuaki*; Fujii, Takashi*; Kanazawa, Seiji*

Japanese Journal of Applied Physics, 55(2), p.026101_1 - 026101_10, 2016/02

https://doi.org/10.7567/JJAP.55.026101

A percolation model of discharge, which can reproduce stochastic behaviors of initial partial discharge to the growth of a stepped leader, is presented. The model uses macroscopic cells, from which a network of electric circuits is defined, and the spatial and temporal evolutions of the electric field and current in the discharge medium are calculated. For each cell, one of two states, either insulator or conductor, which corresponds to neutral gas or ionized plasmas, respectively, is decided. The decision is made on the basis of probability for each calculation cell at each time step, taking the effects of local electric field and current, which enhance ionization and sustain the discharge channel, respectively, into account. The stochastic behavior of discharge is discussed, in conjunction with the characteristic feature of ionization, that is, the ionization occurs not only ahead of the streamer tip where the electric field is enhanced but randomly in the discharge medium.

Statistics of clusters of ionized regions in the simulation of discharge using the percolation model

Sasaki, Akira; Kato, Susumu*

Plasma and Fusion Research (Internet), 9(Sp.2), p.3401120_1 - 3401120_4, 2014/07

https://doi.org/10.1585/pfr.9.3401120

We calculate sudden formation of complex path of discharges with branching and detouring using the percolation model. The simulation is based on a cell model, the discharge is considered to occur when a connection between the positive and negative electrode by the patches of the ionized regions is established. The model is applied to the calculation of the temporal evolution of discharge in the SF, to reproduce experimental behaviors of the discharge. Before the breakdown occurs, the ionized regions, which are initially produced randomly, grows in space, connects each other, forming clusters of the ionized region. It is shown that the statistics of the clusters, such as the distribution of the size and number of clusters have significant effect to the electric property of the discharge.

Molecular and carbon isotope compositions of hydrocarbon gas in Neogene sedimentary rocks in Horonobe area, northern Hokkaido, Japan

Funaki, Hironori; Ishiyama, Koji*; Waseda, Amane*; Kato, Susumu*; Watanabe, Kunio*

Chigaku Zasshi, 121(6), p.929 - 945, 2012/12

https://doi.org/10.5026/jgeography.121.929

Molecular and carbon isotope compositions of hydrocarbon gas have information related to their generation, migration and accumulation, and serve evaluations of gas permeability in sedimentary rocks. We conducted headspace gas analysis at the cores (below 500 m depth) to evaluate gas permeability in Neogene sedimentary rocks in the Horonobe, Hokkaido, Japan. As a result, it was shown that hydrocarbon gases were almost biogenic methane. Further analysis of these data indicated that concentration and carbon isotope of methane varied carbon isotopic fractionation during anaerobic microbial oxidation and migration near the faults. A formation of high concentration and light carbon isotope of methane at present in the study area is low gas permeability and is less affected by secondary post-generic process.

The "Study on nuclear data by using a high intensity pulsed neutron source for advanced nuclear system" nuclear data project and the characteristics of the neutron beam line for the capture cross section experiments at J-PARC

Kiyanagi, Yoshiaki*; Kino, Koichi*; Furusaka, Michihiro*; Hiraga, Fujio*; Kamiyama, Takashi*; Kato, Kiyoshi*; Igashira, Masayuki*; Katabuchi, Tatsuya*; Mizumoto, Motoharu*; Oshima, Masumi; et al.

Journal of the Korean Physical Society, 59(2), p.1781 - 1784, 2011/08

https://doi.org/10.3938/jkps.59.1781

The project of the comprehensive nuclear data research for the development of the advanced reactor systems had been executed successfully by eight organizations from 2005 to 2009. In this project, we constructed the pulsed neutron beamline that was aimed to obtain neutron capture cross-sections of long-lived fission products and minor actinides accurately. The energy spectra, spatial distributions, and pulses of the beam were studied by measurements and simulation calculations, and they were found to be consistent with those of the beamline design. In this paper, we present the overview of the project and the properties of the neutron beam provided by this beam line.

Percolation simulation of laser-guided electrical discharges

Sasaki, Akira; Kishimoto, Yasuaki*; Takahashi, Eiichi*; Kato, Susumu*; Fujii, Takashi*; Kanazawa, Seiji*

Physical Review Letters, 105(7), p.075004_1 - 075004_4, 2010/08

https://doi.org/10.1103/PhysRevLett.105.075004

A three-dimensional simulation of laser guided-discharges based on the percolation is presented. The model includes both local growth of a streamer due to the enhanced electric field at the tip and propagation of a leader by remote ionization such that caused by runaway electrons. The stochastic behavior of the discharge through preformed plasma channel is reproduced by the calculation, which shows complex path with detouring and bifurcation. The probability of guiding is investigated with respect to the ionized, conductive fraction along the channel.

Simulation of initial discharge path using combined percolation and electric circuit model

Sasaki, Akira; Takahashi, Eiichi*; Kato, Susumu*; Kishimoto, Yasuaki*

Denki Gakkai Parusu Pawa, Hoden Godo Kenkyukai Shiryo (PPT-09-95, ED-09-139), p.9 - 13, 2009/10

A new simulation model of the initiation of high pressure discharge is presented. The model reproduces branching and detouring properties of the discharge path. The model is based on combined random percolation and electric circuit models. We show that the idea of phase transition allows one to renormalize the effect of elementary atomic processes and to perform calculation of the discharge path with a realistic scale (mm to km). As a simple application of the model, discharge through a pre-ionized channel created by a laser irradiation, is investigated, which shows stochastic behaviors of the discharge guiding.

Numerical modeling of atomic-molecule processes for discharge and lighting

Kato, Susumu*; Takahashi, Eiichi*; Sasaki, Akira; Kishimoto, Yasuaki*

Purazuma, Kaku Yugo Gakkai-Shi, 84(8), p.477 - 483, 2008/08

https://ci.nii.ac.jp/naid/110006881125

no abstracts in English

Development of systematic compilation method to exhibit the level of the confidence on the assessment

Oi, Takao; Kato, Tomoko; Kawachi, Susumu; Kawamura, Makoto

JAEA-Research 2008-014, 14 Pages, 2008/03

JAEA-Research-2008-014.pdf:2.93MB

The method contributing to the improvement of confidence and the systematization of the various information and knowledge under the responsibility of each researcher has examined. As a result, "a systematic compilation method to exhibit the level of the confidence on the assessments" has been developed based on the approach of the international quality management system. It is possible to manifest the aims, intention, contents, approach and process of the study by compiling and presenting the results of the studies using this method. In addition, transparency and traceability would be shown and the adequacy of the obtained result would be claimed by researcher through the conformity assessment for the result of the study. These results would contribute the understanding of reader and improvement of confidence.