Wakui, Takashi; Takagishi, Yoichi*; Futakawa, Masatoshi
Materials, 16(17), p.5830_1 - 5830_16, 2023/09
Cavitation damage on the mercury target vessel is induced by proton beam injection in mercury. The prediction method of the cavitation damage using Monte Carlo simulations was proposed taking into account of the uncertainties of the position of cavitation bubbles and impact pressure distributions. The distribution of impact pressure attributed to individual cavitation bubble collapsing was assumed to be the Gaussian distribution, and the probability distribution of the maximum value of impact pressures was assumed to be three kinds of distributions; the delta function, the Gaussian and Weibull distributions. Two parameters were estimated using Bayesian optimization by comparing the distribution of the cavitation damage obtained from experiment with that of accumulated plastic strain obtained from the simulation. It was found that the results obtained using the Weibull distribution reproduced the actual cavitation erosion phenomenon better than the other results.
Kubo, Kotaro; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*
Journal of Nuclear Science and Technology, 60(4), p.359 - 373, 2023/04
Probabilistic risk assessment (PRA) is an essential approach to improving the safety of nuclear power plants. However, this method includes certain difficulties, such as modeling of combinations of multiple hazards. Seismic-induced flooding scenario includes several core damage sequences, i.e., core damage caused by earthquake, flooding, and combination of earthquake and flooding. The flooding fragility is time-dependent as the flooding water propagates from the water source such as a tank to compartments. Therefore, dynamic PRA should be used to perform a realistic risk analysis and quantification. This study analyzed the risk of seismic-induced flooding events by coupling seismic, flooding, and thermal-hydraulics simulations, considering the dependency between multiple hazards explicitly. For requirements of safety improvement, especially in light of the Fukushima Daiichi Nuclear Power Plant accident, sensitivity analysis was performed on the seismic capacity of systems, and the effectiveness of alternative steam generator injection by a portable pump was estimated. We demonstrate the use of this simulation-based dynamic PRA methodology to evaluate the risk induced by a combination of hazards.
Omer, M.; Shizuma, Toshiyuki*; Hajima, Ryoichi*; Koizumi, Mitsuo
Dai-43-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2022/11
Omer, M.; Shizuma, Toshiyuki*; Hajima, Ryoichi*; Koizumi, Mitsuo
Radiation Physics and Chemistry, 198, p.110241_1 - 110241_7, 2022/09
Igaku Butsuri, 41(4), P. 194, 2021/12
Number of medical uses of Particle and Heavy Ion Transport code System (PHITS) has been increased due to the recent high demands of medical use of radiations. The summary of such research works was described in the review article on medical application of Particle and Heavy Ion Transport code System PHITS published in Radiological Physics and Technology in 2021. There was a request from the editorial board of Japan Society of Medical Physics (JSMP) for writing an introductory article of this article in their internal journal. The research works on medical applications described in the review article, useful functions for medical application in PHITS, and newly opened user forum of PHITS have been introduced.
Furuta, Takuya; Sato, Tatsuhiko
Radiological Physics and Technology, 14(3), p.215 - 225, 2021/09
Number of the PHITS users has steadily increased since 2010 from when it is officially counted. Among them, increase of new users in medical physics is outstanding. Many research works in medical physics using PHITS have been published and the applications are widely spread in different fields such as applications to different types of radiotherapy, shielding calculations of medical facilities, application to radiation biology, and research and development of medical tools. In this article, we will introduce useful functions for medical application in PHITS by referring to examples of various medical applications.
Malins, A.; Imamura, Naohiro*; Niizato, Tadafumi; Takahashi, Junko*; Kim, M.; Sakuma, Kazuyuki; Shinomiya, Yoshiki*; Miura, Satoru*; Machida, Masahiko
Journal of Environmental Radioactivity, 226, p.106456_1 - 106456_12, 2021/01
Malins, A.; Ochi, Kotaro; Machida, Masahiko; Sanada, Yukihisa
Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.147 - 154, 2020/10
Riyana, E. S.; Okumura, Keisuke; Terashima, Kenichi; Matsumura, Taichi; Sakamoto, Masahiro
Mechanical Engineering Journal (Internet), 7(3), p.19-00543_1 - 19-00543_8, 2020/06
Malins, A.; Machida, Masahiko; Vu, TheDang; Aizawa, Kazuya; Ishida, Takekazu*
Nuclear Instruments and Methods in Physics Research A, 953, p.163130_1 - 163130_7, 2020/02
Omer, M.; Hajima, Ryoichi*
New Journal of Physics (Internet), 21(11), p.113006_1 - 113006_10, 2019/11
Furuta, Takuya; El Basha, D.*; Iyer, S. S. R.*; Correa Alfonso, C. M.*; Bolch, W. E.*
Journal of Radiological Protection, 39(3), p.825 - 837, 2019/09
Despite large variation of human eye, only one computational eye model has been adopted in almost all the radiation transport simulation studies. We thus adopted a new scalable and deformable eye model and studied the radiation exposure by electrons, photons, and neutrons in the standard radiation fields such as AP, PA, RLAT, ROT, by using Monte Carlo radiation transport code PHITS. We computed the radiation exposure for 5 eye models (standard, large, small, myopic, hyperopic) and analyzed influence of absorbed dose in ocular structures on eye size and shape. Dose distribution of electrons is conformal and therefore the absorbed doses in ocular structures depend on the depth location of each ocular structure. We thus found a significant variation of the absorbed doses for each ocular structure for electron exposure due to change of the depth location affected by eye size and shape. On the other hand only small variation was observed for photons and neutrons exposures because of less conformal dose distribution of those particles.
Hashimoto, Shintaro; Sato, Tatsuhiko
Journal of Nuclear Science and Technology, 56(4), p.345 - 354, 2019/04
Particle transport simulations based on the Monte Carlo method have been applied to shielding calculations. Estimation of not only statistical uncertainty related to the number of trials but also systematic one induced by unclear physical quantities is required to confirm the reliability of calculated results. In this study, we applied a method based on analysis of variance to shielding calculations. We proposed random- and three-condition methods. The first one determines randomly the value of the unclear quantity, while the second one uses only three values: the default value, upper and lower limits. The systematic uncertainty can be estimated adequately by the random-condition method, though it needs the large computational cost. The three-condition method can provide almost the same estimate as the random-condition method when the effect of the variation is monotonic. We found criterion to confirm convergence of the systematic uncertainty as the number of trials increases.
Rossi, F.; Rodriguez, D.; Takahashi, Tone; Seya, Michio; Koizumi, Mitsuo
Nihon Kaku Busshitsu Kanri Gakkai Dai-39-Kai Nenji Taikai Rombunshu (CD-ROM), 3 Pages, 2018/11
This paper (presentation) reports on the design study for seeking compactness of moderator (and reflector) structure for the Delayed Gamma-ray Spectroscopy Non Destructive Assay system to be applied for verification of fissile isotopic (Pu-239, Pu-241 and U-235) composition ratio in High Radioactive Nuclear Material sample such as dissolved solution of reprocessing facility. We first investigated advantages and disadvantages of using different compact neutron sources as DT and DD neutron generators. This led us to the conclusion of using DD sources to achieve a compact (and practical) NDA system. Based on MCNP simulations, with the use of a DD neutron generator, a preliminary optimization study was performed and will be shown here.
El Basha, D.*; Furuta, Takuya; Iyer, S. S. R.*; Bolch, W. E.*
Physics in Medicine & Biology, 63(10), p.105017_1 - 105017_13, 2018/05
With recent changes in the recommended annual limit on eye lens exposures to ionizing radiation by International Commission on Radiological Protection, there is considerable interest in predictive computational dosimetry models of the human eye and its various ocular structures. Several computational eye models to date have been constructed for this purpose but they are typically constructed of nominal size and of a roughly spherical shape associated with the emmetropic eye. We therefore constructed a geometric eye model that is both scalable (allowing for changes in eye size) and deformable (allowing for changes in eye shape), and that is suitable for use in radiation transport studies of ocular exposures and radiation treatments of eye disease. As an example, electron and photon anterior-posterior radiation transport with the constructed eye model was conducted and analyzed resultant energy-dependent dose profiles. Due to anterior-posterior irradiation, the energy dose response was shifted to higher energy for a larger-size eye or an axially deformed eye in prolate shape because the structures were located in deeper depth compared to the normal eye.
Takada, Shusuke*; Okudaira, Takuya*; Goto, Fumiya*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Nakao, Taro*; Sakai, Kenji; Shimizu, Hirohiko*; et al.
Journal of Instrumentation (Internet), 13(2), p.P02018_1 - P02018_21, 2018/02
Lerendegui-Marco, J.*; Corts-Giraldo, M. A.*; Guerrero, C.*; Harada, Hideo; Kimura, Atsushi; n_TOF Collaboration*; 114 of others*
EPJ Web of Conferences, 146, p.03030_1 - 03030_4, 2017/09
Maeda, Makoto; Komeda, Masao; Tobita, Hiroshi; Ozu, Akira; Kureta, Masatoshi; Bogucarska, T.*; Crochemore, J. M.*; Varasano, G.*; Pedersen, B.*
Dai-37-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu (CD-ROM), 7 Pages, 2017/02
JAEA and EC/JRC are carrying out collaborative research to develop NDA techniques that can be utilized for quantification of high radioactive special nuclear materials such as spent fuel and next generation minor actinide fuels. In the research, reliability of neutron transport codes is important because it is utilized for design and development of a demonstration system of next-generation Differential Die-away (DDA) technique in JAEA. In order to evaluate the reliability, actual neutron flux distribution in a sample cavity was examined in PUNITA device using JRC type DDA technique and JAWAS-T device using JAEA type DDA technique, and then the measurement results were compared with the simulation results obtained by the neutron transport codes. The neutron flux distribution in the target matrix was also examined in the PUNITA and compared with the simulation results. We report on the measurement and simulation results of the neutron flux distribution and evaluation results of the reliability of the neutron transport codes.
Maeda, Makoto; Komeda, Masao; Ozu, Akira; Kureta, Masatoshi; Toh, Yosuke; Bogucarska, T.*; Crochemore, J. M.*; Varasano, G.*; Pedersen, B.*
EUR-28795-EN (Internet), p.694 - 701, 2017/00