Present status and future perspective of R&D for 3D-ADRES (3-Dimensional Air Dose Rate Evaluation System); Evaluation scheme for air dose rate distributions in city and forest areas towards Fukushima's revitalization

Kim, M.; Malins, A.; Machida, Masahiko; Yoshimura, Kazuya; Saito, Kimiaki; Yoshida, Hiroko*; Yanagi, Hideaki*; Yoshida, Toru*; Hasegawa, Yukihiro*

RIST News, (67), p.3 - 15, 2021/09

https://www.rist.or.jp/rnews/67/ristnews_67.html

no abstracts in English

Quality and performance of a pseudo-random number generator in massively parallel plasma particle simulations

Matsuoka, Seikichi*; Satake, Shinsuke*; Idomura, Yasuhiro; Imamura, Toshiyuki*

Proceedings of Joint International Conference on Mathematics and Computation, Supercomputing in Nuclear Applications and the Monte Carlo Method (M&C + SNA + MC 2015) (CD-ROM), 13 Pages, 2015/04

The quality and performance of a parallel pseudo-random number generator (PRNG), KMATH_RANDOM, are investigated using a Monte Carlo particle simulation code for the plasma transport. The library is based on Mersenne Twister with jump routines and provides a numerical tool which is suitable and easy-to-use on massively parallel supercomputers such as K-computer. The library enables the particle code to increase the parallelization up to several thousand processes without loosing the quality and performance of the PRNG. As a result, the particle code can use large amounts of random numbers, which results in removing unphysical phenomena caused by a numerical noise.

Particle and heavy ion transport code system, PHITS, version 2.52

Sato, Tatsuhiko; Niita, Koji*; Matsuda, Norihiro; Hashimoto, Shintaro; Iwamoto, Yosuke; Noda, Shusaku; Ogawa, Tatsuhiko; Iwase, Hiroshi*; Nakashima, Hiroshi; Fukahori, Tokio; et al.

Journal of Nuclear Science and Technology, 50(9), p.913 - 923, 2013/09

https://doi.org/10.1080/00223131.2013.814553

An upgraded version of the Particle and Heavy Ion Transport code System, PHITS 2.52, was developed and released to public. The new version has been greatly improved from the previous released version, PHITS 2.24, in terms of not only the code itself but also the contents of its package such as attached data libraries. Owing to these improvements, PHITS became a more powerful tool for particle transport simulation applicable to various research and development fields such as nuclear technology, accelerator design, medical physics, and cosmic-ray research.

PHITS: Particle and Heavy Ion Transport code System, Version 2.23

Niita, Koji*; Matsuda, Norihiro; Iwamoto, Yosuke; Iwase, Hiroshi*; Sato, Tatsuhiko; Nakashima, Hiroshi; Sakamoto, Yukio; Sihver, L.*

JAEA-Data/Code 2010-022, 189 Pages, 2010/10

JAEA-Data-Code-2010-022.pdf:1.89MB

The Particle and Heavy-Ion Transport code System PHITS has been developed under the collaboration of JAEA, RIST and KEK, as an upgraded version of the NMTC/JAM code developed. PHITS can deal with the transport of all particles and heavy ions over wide energy ranges, using several nuclear reaction models and nuclear data libraries. The geometrical configuration of the simulation can be setup by GG (General Geometry) or CG (Combinatorial Geometry). Various quantities such as heat, track length and production yields can be deduced from the simulation, using implemented estimator functions called "tally". The code also has a function to draw 2D figures of the calculated results as well as the setup geometries, using ANGEL. Owing to these features, PHITS has been widely used for various purposes such as designs of accelerator shielding, radiation therapy and space exploration. This document provides the manual of PHITS.

Loop formation by ion irradiation in yttria stabilized zirconia

Hojo, Tomohiro*; Yamamoto, Hiroyuki; Aihara, Jun; Furuno, Shigemi*; Sawa, Kazuhiro; Sakuma, Takashi*; Hojo, Kiichi

Nuclear Instruments and Methods in Physics Research B, 250(1-2), p.101 - 105, 2006/09

https://doi.org/10.1016/j.nimb.2006.04.093

Yttria stabilized zirconia (YSZ) is a candidate material focused as optical and insulating materials in nuclear reactors. Therefore, it is useful to investigate defect formation during irradiation, in order to assess YSZ resistance to radiation damage. In the present study, in situ transmission electron microscopy (TEM) observations were performed on YSZ during 30 keV Ne irradiation in the temperature range of 723-1123 K. For irradiations below 1023 K, defect clusters and bubbles were formed simultaneously. On the other hand, at 1123 K, only bubbles were formed in the initial stage of irradiation. Loops formed later following the bubble formation. It was also observed that, in the early stage of irradiation above 923 K, larger bubbles were formed along the loop planes compared with other areas. TEM observations indicated that dislocation loops formed on three kinds of crystallographic planes: namely, (100), (111) and (112) planes.

Characterization of loops in YSZ by Ne irradiation

Hojo, Tomohiro*; Yasuhara, Akira*; Yamamoto, Hiroyuki; Aihara, Jun; Furuno, Shigemi*; Sawa, Kazuhiro; Sakuma, Takashi*; Hojo, Kiichi

no journal, , 

Yttria stabilized zirconia (YSZ) is a candidate material as optical and insulating materials in nuclear reactors. The investigation of defect formation under the ion irradiation is therefore required. In the present study, YSZ was irradiated with 30 keV Ne ions with a flux of 310 ions/cm at 923 K. Compositional changes were analyzed by energy dispersive X-ray spectrometer (EDS) equipped with transmission electron microscope. From the observation of micrographs, it was shown that dislocation loops were formed on three kinds of crystallographic planes, namely, on (110), (111) and (112) planes. The dislocation loops inhabiting on (110) crystal plane were analyzed by EDS along the loops. The average composition between the vicinity of loops and the matrix is compared. On the basis of the obtained results, it is observed composition of oxygen on loops decreases and zirconium increases compared with the matrix.

Particle and heavy ion transport code system; PHITS

Sato, Tatsuhiko; Niita, Koji*; Matsuda, Norihiro; Hashimoto, Shintaro; Iwamoto, Yosuke; Furuta, Takuya; Iwase, Hiroshi*; Noda, Shusaku; Ogawa, Tatsuhiko; Nakashima, Hiroshi; et al.

no journal, , 

General features of the Particle and Heavy Ion Transport Code System, PHITS, will be described at the meeting.

Full-f gyrokinetic simulations for neoclassical toroidal viscosity in a perturbed tokamak configuration

Matsuoka, Seikichi*; Idomura, Yasuhiro; Satake, Shinsuke*

no journal, , 

http://meetings.aps.org/link/BAPS.2014.DPP.CP8.34

A magnetic field perturbation in tokamak plasmas plays a key role in determining the intrinsic rotation and velocity shear, since even a small perturbation can break the axisymmetry in the toroidal direction and induces the finite neoclassical toroidal viscosity (NTV). A simulation study for the NTV evaluation in an axisymmetric tokamak with a small resonant magnetic field perturbation using the full-f gyrokinetic Eulerian code GT5D is presented. The magnetic field perturbation is included in the particle orbit of GT5D only through the Hamiltonian by replacing the axisymmetric magnetic field with the sum of the axisymmetric field and the perturbation, which enables us to perform GT5D simulations without changing the symplectic structure of the single-particle Lagrangian constructed for the equilibrium (axisymmetric) magnetic field. Numerical results are benchmarked with those obtained by the neoclassical transport code, FORTEC-3D, which solves the drift kinetic equation by Monte Carlo method. The NTV of GT5D with a single-helicity perturbation is found to have a similar peaked profile around the resonant surface as that of FORTEC-3D.

Full-f gyrokinetic simulations of neoclassical toroidal viscosity in perturbed tokamaks

Matsuoka, Seikichi*; Idomura, Yasuhiro; Satake, Shinsuke*

no journal, , 

When non-axisymmetric magnetic perturbations are imposed in axisymmetric tokamaks, broken axisymmetry induces the neoclassical viscosity, and affects momentum transport and resulting plasma rotation profiles. In this work, we estimate the neoclassical toroidal viscosity using full-f gyrokinetic simulations, and verify calculation methods and obtained results. We discuss the parameter dependency of the neoclassical toroidal viscosity in the presence of small resonant magnetic perturbations, based on comparisons against analytic theories and neoclassical transport codes.