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Journal Articles

Simulation code for estimating external gamma-ray doses from a radioactive plume and contaminated ground using a local-scale atmospheric dispersion model

Satoh, Daiki; Nakayama, Hiromasa; Furuta, Takuya; Yoshihiro, Tamotsu*; Sakamoto, Kensaku

PLOS ONE (Internet), 16(1), p.e0245932_1 - e0245932_26, 2021/01

 Times Cited Count:2 Percentile:36.99(Multidisciplinary Sciences)

In this study, we developed a simulation code named SIBYL, which estimates external gamma-ray doses at ground level from radionuclides distributed nonuniformly in atmosphere and on ground. SIBYL can combine with the local-scale atmospheric dispersion model LOHDIM-LES, and calculate the dose distributions according to the map of the activity concentrations simulated by LOHDIM-LES. To apply the SIBYL code to emergency responses of nuclear accidents, the time-consuming three-dimensional radiation transport simulations were performed in advance using the general-purpose Monte Carlo code PHITS, and then the results were compiled to the database for the SIBYL's dose calculations. Moreover, SIBYL can consider the dose attenuation by obstacles and the changes of terrain elevations. To examine the accuracy of SIBYL, typical five cases including $$^{85}$$Kr emission from a ventilation shaft and $$^{137}$$Cs dispersion inside urban area were investigated. The results of SIBYL agreed within 10% with those of PHITS at the most of target locations. Furthermore, the calculation speed was approximately 100 times faster than that of PHITS.

Journal Articles

JAEA activities related to the use of computer programs and databases in the nuclear field

Suzuki, Yoshio; Otani, Takayuki; Sakamoto, Kensaku; Takakura, Masahiro*; Kuwabara, Yasuhiro*

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.287 - 294, 2020/10

HPC Technology Promotion Office, Center for Computational Science and e-systems (CCSE) of Japan Atomic Energy Agency (JAEA) is responsible for the administration of computer programs (CPs) and databases (DBs) developed in JAEA to disseminate R&D results in JAEA to the outside and improve R&D efficiency. The information of these CPs and DBs can be found using Program and Database retrieval System (PRODAS) (, which is developed by our team. Those in Japan can also obtain CPs and DBs in the nuclear field possessed in OECD NEA Data Bank (NEADB), Radiation Safety Information Computational Center (RSICC) in the United States, and International Atomic Energy Agency (IAEA). In this paper, the recent situation of possession and dispatch of CPs and DBs developed within JAEA and the frameworks to obtain and provide CPs and DBs in nuclear field worldwide are presented.

Journal Articles

Numerical simulation on influence to fluid behavior with a change of flow channel cross-sectional area by a spacer

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Kashika Joho Gakkai-Shi, 35(Suppl.2), p.59 - 60, 2015/09

no abstracts in English

Journal Articles

Development of a pulsed neutron three-dimensional imaging system using a highly sensitive image-intensifier at J-PARC

Segawa, Mariko; Oi, Motoki; Kai, Tetsuya; Shinohara, Takenao; Kureta, Masatoshi; Sakamoto, Kensaku; Imaki, Tadashi*

Nuclear Instruments and Methods in Physics Research A, 769, p.97 - 104, 2015/01

 Times Cited Count:1 Percentile:18.05(Instruments & Instrumentation)

Journal Articles

Numerical analysis on thermal-hydraulics around a spacer in a supercritical fluid

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Nihon Kikai Gakkai Dai-27-Kai Keisan Rikigaku Koenkai Rombunshu (CD-ROM), 2 Pages, 2014/11

no abstracts in English

Journal Articles

2D neutron diffraction imaging on an ammonite

Shamoto, Shinichi; Kodama, Katsuaki; Imaki, Tadashi*; Nakatani, Takeshi; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Masuko, Kenji*; Sakamoto, Kensaku; Yamaguchi, Kenji; Suzuya, Kentaro; et al.

JPS Conference Proceedings (Internet), 1, p.014011_1 - 014011_5, 2014/03

2D neutron diffraction imaging of an ammonite fossil was carried out at high-intensity total diffractometer NOVA in J-PARC. Observed diffraction profiles consist of calcite, siderite and amorphous structures.

JAEA Reports

Visualization environment of the large-scale data of JAEA's supercomputer system

Sakamoto, Kensaku; Hoshi, Yoshiyuki*

JAEA-Testing 2013-002, 80 Pages, 2013/11


On research and development of various fields of nuclear energy, visualization of calculated data is especially useful to understand the result of simulation in an intuitive way. Many researchers who run simulations on the supercomputer in Japan Atomic Energy Agency (JAEA) are used to transfer calculated data files from the supercomputer to their local PCs for visualization. In recent years, as the size of calculated data has gotten larger with improvement of supercomputer performance, reduction of visualization processing time as well as efficient use of JAEA network is being required. As a solution, we introduced a remote visualization system which has abilities to utilize parallel processors on the supercomputer and to reduce the usage of network resources by transferring data of intermediate visualization process. This paper reports a study on the performance of image processing with the remote visualization system. The visualization processing time is measured and the influence of network speed is evaluated by varying the drawing mode, the size of visualization data and the number of processors. Based on this study, a guideline for using the remote visualization system is provided to show how the system can be used effectively. An upgrade policy of the next system is also shown.

Journal Articles

Thermal-hydraulic simulation in simulated subchannels of a nuclear reactor at supercritical pressure condition

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Nihon Kikai Gakkai Dai-26-Kai Keisan Rikigaku Koenkai Rombunshu (CD-ROM), p.703_1 - 703_2, 2013/11

no abstracts in English

Journal Articles

A Study on flow field of purge gas for tritium transfer through breeder pebble bed in fusion blanket

Seki, Yohji; Ezato, Koichiro; Yokoyama, Kenji; Enoeda, Mikio; Kubota, Jinichi*; Sakamoto, Kensaku

Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 8 Pages, 2012/12

Japan Atomic Energy Agency has been performing R&D and design of a blanket module of a nuclear fusion reactor. Pebbles of a ceramic tritium breeder are packed in a container of the blanket. Helium purge gas is applied as a transport fluid in a tritium recovery system. Prediction of the flow phenomena with a tritium transfer is important for designs of the container. A purpose of our research is to establish and verify a method for a prediction of the flow in the pebble bed. In this study, pressure drops of the helium purge gas through the pebble bed were measured up to 100 L/min of flow rate. Reliability of prediction ability of the pressure drop was validated by this experiment within the flow rate which is less than 40 L/min. A numerical simulation for the flow field through the pebble bed also has been performed. Consequently, the velocity distributions are quantitatively and qualitatively obtained at near the wall and the center region in the pebble bed.

Journal Articles

R&D of a zooming analysis to verify a seismic simulation of an entire nuclear plant

Suzuki, Yoshio; Hoshi, Yoshiyuki*; Sakamoto, Kensaku; Nakajima, Norihiro

Proceedings of 4th International Conference on Computational Methods (ICCM 2012) (USB Flash Drive), 9 Pages, 2012/11

We research and develop a three-dimensional vibration simulator for an entire nuclear plant aiming at technical advances for more rational safety assessment of nuclear plant under an earthquake. The simulator includes "an entire structural simulation of ground-building-equipments (beam model)" and "an assembly structural simulation of parts to equipments (solid model)". As one approach to examine the quality of solid model which consists of thousands of parts, we have established a trial tool to perform the assembly structural simulation for a small number of parts by zooming in on a part of equipments in the entire structural simulation, and to compare results. To verify the tool, we applied the tool to static and dynamic simulations for a cantilever with various cross sections, and a static simulation of a small number of parts of nuclear plant, and confirmed results for solid model well coincide with those for beam model.

Journal Articles

Numerical research on fluid mixing characteristics in a non-heated parallel channel by supercritical freon

Kitamura, Tatsuaki*; Sakamoto, Kensaku; Takase, Kazuyuki

Kashika Joho Gakkai-Shi, 32(Suppl.2), p.239 - 240, 2012/10

In the thermal-hydraulic design of supercritical water-cooled reactors, it is required to establish a thermal-hydraulic analysis method which can simulate the heat transfer and fluid flow characteristics of supercritical fluids precisely. A crossing flow is a phenomenon in which the fluid flowing through the inside of a fuel bundle in the perpendicular direction moves between subchannels to a transverse direction. The crossing flow influences the removal heat of a reactor core greatly. In the present study, results of the preliminary crossing flow simulation are described.

Journal Articles

Modifications to the edge radial electric field by angular momentum injection in JT-60U and their implication for pedestal transport

Kamiya, Kensaku; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Yoshida, Maiko; Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; et al.

Nuclear Fusion, 52(11), p.114010_1 - 114010_12, 2012/10

 Times Cited Count:10 Percentile:41.37(Physics, Fluids & Plasmas)

Depending on the direction of the external tangential momentum input, substantial changes in not only toroidal but also poloidal flows for the carbon impurity ions are observed at around the $$E$$$$_{r}$$-well region. The shear in the edge $$E$$$$_{r}$$ becomes wider in the co-NBI case, while the edge $$E$$$$_{r}$$-well becomes deeper in the counter-NBI case.

Journal Articles

Reduction of ion thermal diffusivity inside a magnetic island in JT-60U tokamak plasma

Ida, Katsumi*; Kamiya, Kensaku; Isayama, Akihiko; Sakamoto, Yoshiteru; JT-60 Team

Physical Review Letters, 109(6), p.065001_1 - 065001_4, 2012/08

 Times Cited Count:42 Percentile:84.64(Physics, Multidisciplinary)

The transport inside the magnetic island is investigated in the plasma during the transient phase after the back transition from $$H$$-mode to $$L$$-mode, where a sudden drop of temperature outside the magnetic island causes a peaking of ion temperature at the $$O$$-point inside the magnetic island.

Journal Articles

Engineering study of gas flow in breeder pebble bed for fusion blanket

Seki, Yohji; Yoshikawa, Akira; Tanigawa, Hisashi; Hirose, Takanori; Ezato, Koichiro; Enoeda, Mikio; Sakamoto, Kensaku

Dai-17-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.265 - 266, 2012/06

In the case of a water cooled ceramic breeder in a blanket, pebbles of a ceramic tritium breeder are packed in a container constituted by a partition plate. Helium purge gas is applied as a transport fluid in a tritium recovery system. It is of importance to build database of a pressure drop as part of a design of the tritium recovery system. In this experimental study, the pressure drops of He gas through pebble bed were measured within the wide range of a flow rate up to 100 L/min. The results indicate that a laminar flow is dominant and the pressure drop was correctly predicted by the empirical equation within a part of flow rate. Reliability of prediction ability of pressure drop was established by this experiment within the flow rate which is less than 60 L/min. Moreover, this paper describes that slight difference between the experimental result and the empirical equation within a range of flow rate from 60 L/min to 100 L/min.

JAEA Reports

Evaluation of fundamental performance of JAEA's new supercomputer system

Sakamoto, Kensaku; Shimizu, Futoshi; Tsuruoka, Takuya*; Nemoto, Toshiyuki*; Ishikawa, Naota*

JAEA-Testing 2011-005, 88 Pages, 2011/11


A new supercomputer system was deployed at JAEA in March 2010. The system is mainly composed of a large scale Linux cluster system (PRIMERGY BX900: 200Tflops) and a lead off system of RIKEN's K computer (FX1: 12Tflops), whose purposes are to deliver a high-performance parallel computing environment and application code development environment for the K computer, respectively. In this report, we present results of the evaluation of fundamental performance of the system.

Journal Articles

Edge pedestal characteristics in JET and JT-60U tokamaks under variable toroidal field ripple

Urano, Hajime; Saibene, G.*; Oyama, Naoyuki; Parail, V.*; de Vries, P.*; Sartori, R.*; Kamada, Yutaka; Kamiya, Kensaku; Loarte, A.*; L$"o$nnroth, J.*; et al.

Nuclear Fusion, 51(11), p.113004_1 - 113004_10, 2011/11

 Times Cited Count:10 Percentile:41.55(Physics, Fluids & Plasmas)

The effect of TF ripple on the edge pedestal characteristics are examined in JET and JT-60U. By the installation of ferritic inserts, TF ripple was reduced from $$1%$$ to $$0.6%$$ in JT-60U. In JET, TF ripple was varied from $$0.1%$$ to $$1%$$ by feeding different currents to TF coils. The pedestal pressure was similar with reduced ripple in JT-60U. In JET, no clear difference of the pedestal characteristics was also observed. The edge toroidal rotation clearly decreased in counter direction by increased TF ripple. However, in JT-60U, the ELM frequency decreased by $$sim 20%$$ and the increased ELM loss power by $$30%$$ with reduced ripple. In JET, ELM frequency increases only slightly with increased TF ripple. From this inter-machine experiment, TF ripple less than $$1%$$ does not strongly affect the pedestal pressure. The effect of TF ripple on pedestal characteristics at lower collisionality close to ITER should be investigated as a next step study.

Journal Articles

Spatio-temporal structure of the edge radial electric field during H-mode in JT-60U

Kamiya, Kensaku; Sakamoto, Yoshiteru; Matsunaga, Go; Kojima, Atsushi; Urano, Hajime; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; Ida, Katsumi*; Kurki-Suonio, T.*; et al.

Nuclear Fusion, 51(5), p.053009_1 - 053009_3, 2011/05

 Times Cited Count:13 Percentile:49.95(Physics, Fluids & Plasmas)

We revisited to measure the edge impurity ion dynamic with new CXRS in the hot ion H-mode regime at the high magnetic field having two steps transition where a jump of Ti gradient precedes a jump of impurity Vp. Two discrete phases with different magnitude of Er in the H-phase have been observed. One is the intermediate H-phase having a large Ti gradients without significant Vp of impurity species with moderate magnitude of Er, and the other is the complete H-phase characterized by a large Er.

Journal Articles

Development of the real-time plasma shape movie broadcasting system for JT-60SA

Sueoka, Michiharu; Sakamoto, Kensaku; Shigemori, Yuji*

Heisei-22-Nendo Kumamoto Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 6 Pages, 2011/03

no abstracts in English

Journal Articles

Interactions between MHD instabilities in the wall-stabilized high-$$beta$$ plasmas

Matsunaga, Go; Aiba, Nobuyuki; Shinohara, Koji; Sakamoto, Yoshiteru; Takechi, Manabu; Suzuki, Takahiro; Asakura, Nobuyuki; Isayama, Akihiko; Oyama, Naoyuki; Yoshida, Maiko; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

Journal Articles

JAEA's new supercomputer system

Shimizu, Futoshi; Sakamoto, Kensaku; Yoshioka, Yuji*

FAPIG, (182), p.26 - 29, 2011/02

no abstracts in English

58 (Records 1-20 displayed on this page)