Kusakabe, Kazuaki*; Watanabe, Masanori; Nishiuchi, Masashi*; Yamasaki, Takuhei*; Inoue, Hiromi*
Kankyo Hoshano Josen Gakkai-Shi, 11(1), p.15 - 23, 2023/03
The spread of radioactive materials caused by the Fukushima Daiichi Nuclear Power Plant accident that occurred in March 2011 contaminated a wide area that includes Fukushima Prefecture. Although air dose rates in Fukushima Prefecture have been steadily decreasing because of decontamination and the physical decay of radioactive materials, it is important to confirm the sustainability of decontamination effects in living areas and to predict future trends in air dose rates to reassure residents who are concerned regarding radiation exposure. This report aims to confirm the sustainability of the decontamination effects in public facilities after decontamination on a continuous and detailed basis, and to verify whether the future transition in air dose rates can be predicted using existing model. The air dose rates in public facilities after decontamination were measured via fixed-point and walking surveys, and the changes in air dose rates were clarified quantitatively for each facility. The measured values were compared with values obtained using existing model, and prediction accuracy was considered. The results showed that there was no evident recontamination after decontamination at any of the surveyed facilities, indicating that the decontamination effects were sustained. It was also confirmed that future trends in air dose rates at the facilities after decontamination could be accurately predicted by existing model. Key words: air dose rate, decontamination, future prediction, public facilities.
Maeyama, Shinya*; Watanabe, Tomohiko*; Nakata, Motoki*; Nunami, Masanori*; Asahi, Yuichi; Ishizawa, Akihiro*
Nature Communications (Internet), 13, p.3166_1 - 3166_8, 2022/06
Turbulent transport is a key physics process for confining magnetic fusion plasma. Recent theoretical and experimental studies of existing fusion experimental devices revealed the existence of cross-scale interactions between small (electron)-scale and large (ion)-scale turbulence. Since conventional turbulent transport modelling lacks cross-scale interactions, it should be clarified whether cross-scale interactions are needed to be considered in future experiments on burning plasma, whose high electron temperature is sustained with fusion-born alpha particle heating. Here, we present supercomputer simulations showing that electron scale turbulence in high electron temperature plasma can affect the turbulent transport of not only electrons but also fuels and ash. Electron-scale turbulence disturbs the trajectories of resonant electrons responsible for ion-scale micro-instability and suppresses large-scale turbulent fluctuations. Simultaneously, ion-scale turbulent eddies also suppress electron-scale turbulence. These results indicate a mutually exclusive nature of turbulence with disparate scales. We demonstrate the possibility of reduced heat flux via cross-scale interactions.
Abe, Shinichiro; Sato, Tatsuhiko; Kuroda, Junya*; Manabe, Seiya*; Watanabe, Yukinobu*; Liao, W.*; Ito, Kojiro*; Hashimoto, Masanori*; Harada, Masahide; Oikawa, Kenichi; et al.
Proceedings of IEEE International Reliability Physics Symposium (IRPS 2020) (Internet), 6 Pages, 2020/04
Single event upsets (SEUs) caused by neutrons have been recognized as a serious reliability problem for microelectronic devices on the ground level. In our previous work, it was found that hydride placed in front of the memory chip has considerably impact on SEU cross sections because H ions generated via elastic scattering of neutrons with hydrogen atoms are only emitted in a forward direction. In this study, the effect of components neighboring transistors on neutron-induced SEUs was investigated for 65-nm bulk SRAMs by using PHITS. It was found that the shape of the SEU cross section around few MeV comes from the thickness and the position of components placed in front of transistors when that components do not contains hydrogen atoms. By considering components adjoin memory cells in the test board used in the simulation, measured data at J-PARC BL10 were reproduced well. In addition, it was found that the effect of components neighboring transistors on neutron-induced SERs does not negligible in terrestrial environment.
Abe, Shinichiro; Liao, W.*; Manabe, Seiya*; Sato, Tatsuhiko; Hashimoto, Masanori*; Watanabe, Yukinobu*
IEEE Transactions on Nuclear Science, 66(7, Part2), p.1374 - 1380, 2019/07
Single event upsets (SEUs) caused by secondary cosmic-ray neutrons have recognized as a serious reliability problem for microelectronic devices. Acceleration tests at neutron facilities are convenient to validate soft error rates (SERs) quickly, but some corrections caused from measurement conditions are required to derive realistic SERs at actual environment or to compare other measured data. In this study, the effect of irradiation side on neutron-induced SEU cross sections was investigated by performing neutron transport simulation using PHITS. SERs for 65-nm bulk CMOS SRAMs are estimated using the sensitive volume model. It was found from simulation that SERs for the sealant side irradiation are 30-50% larger than those for the board side irradiation. This difference comes from the difference of production yield and angular distribution of secondary H and He ions, which are the main cause of SEUs. Thus the direction of neutron irradiation should be reported when the result of acceleration tests are published. This result also indicates that SERs can be reduced by equipping device with sealant side facing downward.
Maeyama, Shinya*; Watanabe, Tomohiko*; Idomura, Yasuhiro; Nakata, Motoki*; Nunami, Masanori*
Computer Physics Communications, 235, p.9 - 15, 2019/02
We have implemented the Sugama collision operator in the gyrokinetic Vlasov simulation code, GKV, with an implicit time-integration scheme. The new method is versatile and independent of the details of the linearized collision operator, by means of an operator splitting, an implicit time integrator, and an iterative Krylov subspace solver. Numerical tests demonstrate stable computation over the time step size restricted by the collision term. An efficient implementation for parallel computation on distributed memory systems is realized by using the data transpose communication, which makes the iterative solver free from inter-node communications during iteration. Consequently, the present approach achieves enhancement of computational efficiency and reduction of computational time to solution simultaneously, and significantly accelerates the total performance of the application.
Manabe, Seiya*; Watanabe, Yukinobu*; Liao, W.*; Hashimoto, Masanori*; Nakano, Keita*; Sato, Hikaru*; Kin, Tadahiro*; Abe, Shinichiro; Hamada, Koji*; Tampo, Motonobu*; et al.
IEEE Transactions on Nuclear Science, 65(8), p.1742 - 1749, 2018/08
Recently, the malfunction of microelectronics caused by secondary cosmic-ray muon is concerned as semiconductor devices become sensitive to radiation. In this study, we have performed muon irradiation testing for 65-nm ultra-thin body and thin buried oxide (UTBB-SOI) SRAMs in the Japan Proton Accelerator Research Complex (J-PARC), in order to investigate dependencies of single event upset (SEU) cross section on incident muon momentum and supply voltage. It was found that the SEU cross section by negative muon are approximately two to four times larger than those by positive muon in the momentum range from 35 MeV/c to 39 MeV/c. The supply voltage dependence of muon-induced SEU cross section was measured with the momentum of 38 MeV/c. SEU cross sections decrease with increasing supply voltage, but the decreasing of SEU cross section by negative muon is gentler than that by positive muon. Experimental data of positive and negative muon irradiation with the momentum of 38 MeV/c were analyzed by PHITS. It was clarified that the negative muon capture causes the difference between the SEU cross section by negative muon and that by positive muon.
Liao, W.*; Hashimoto, Masanori*; Manabe, Seiya*; Watanabe, Yukinobu*; Abe, Shinichiro; Nakano, Keita*; Sato, Hikaru*; Kin, Tadahiro*; Hamada, Koji*; Tampo, Motonobu*; et al.
IEEE Transactions on Nuclear Science, 65(8), p.1734 - 1741, 2018/08
Soft error induced by secondary cosmic-ray muon is concerned since susceptibility of semiconductor device to soft error increases with the scaling of technology. In this study, we have performed irradiation tests of muons on 65-nm bulk CMOS SRAM in the Japan Proton Accelerator Research Complex (J-PARC) and measured soft error rate (SER) to investigate mechanism of muon-induced soft errors. It was found that SER by negative muon increases above 0.5 V supply voltage, although SER by positive muon increases monotonically as the supply voltage lowers. SER by negative muon also increases with forward body bias. In addition, negative muon causes large multiple cell upset (MCU) of more than 20 bits and the ratio of MCU events to all the events is 66% at 1.2V supply voltage. These tendencies indicate that parasitic bipolar action (PBA) is highly possible to contribute to SER by negative muon. Experimental data are analyzed by PHITS. It was found that negative muon can deposit larger charge than positive muon, and such events that can deposit large charge may trigger PBA.
Tanaka, Masaru*; Aoyama, Isao*; Ishizaka, Kaoru*; Ohata, Yuki*; Fukuike, Iori*; Kawase, Keiichi; Watanabe, Masanori; Tokizawa, Takayuki; Miyagawa, Hiroshi*; Ishimori, Yuu
JAEA-Research 2017-003, 65 Pages, 2017/06
JAEA Ningyo-toge Environmental Engineering Center and Fukushima Environmental Safety Center have same challenges in risk communication. As reference, similar domestic cases were investigated by our two Centers, and requirements for building long-term relationship were clarified. As follows; (1) Develop new relationship with various stakeholders in the region. (2) Make better use of existing resources (personnel, land and facilities, etc.). (3) Make a concerted effort to create new values with local stakeholders. (4) Make an opportunity which local stakeholders confirm safety and build confidence to the project. These efforts will enhance the opportunities for operators and residents to learn about environment management and environmental protection.
Maeyama, Shinya*; Watanabe, Tomohiko*; Idomura, Yasuhiro; Nakata, Motoki*; Ishizawa, Akihiro*; Nunami, Masanori*
Nuclear Fusion, 57(6), p.066036_1 - 066036_10, 2017/05
Multi-scale plasma turbulence including electron and ion temperature gradient (ETG/ITG) modes has been investigated by means of electromagnetic gyrokinetic simulations. Triad transfer analyses on nonlinear mode coupling reveal cross-scale interactions between electron and ion scales. One of the interactions is suppression of electron-scale turbulence by ion- scale turbulence, where ITG-driven short-wavelength eddies act like shear flows and suppress ETG turbulence. Another cross-scale interaction is enhancement of ion-scale turbulence in the presence of electron-scale turbulence. This is caused via short-wavelength zonal flows, which are created by the response of passing kinetic electrons in ITG turbulence, suppress ITG turbulence by their shearing, and are damped by ETG turbulence. In both cases, sub-ion-scale structures between electron and ion scales play important roles in the cross-scale interactions.
Kawase, Keiichi; Kitano, Mitsuaki; Watanabe, Masanori; Yoshimura, Shuichi; Kikuchi, Shiro; Nishino, Katsumi*
JAEA-Review 2017-006, 173 Pages, 2017/03
Survey of a transition of the air and surface dose rate was conducted for the area where the Cabinet Office decontamination model demonstration project was implemented. The area includes 15 districts in 9 municipalities identified by the Ministry of the Environment. We investigated 11 times from October, 2012 to October, 2015. Measurement of the air dose rate in this study was carried out in two methods using the fixed-point measurement and gamma plotter H using a NaI scintillation survey meter etc. As fixed-point measurement, set measurement point in the first survey for (fixed point), it was subjected to measurement of the surface dose rate to continue (1cm height) and space dose rate (1m height). In addition surface specific dose rate distribution measurement using a gamma plotter H (5cm and 1m height) was also performed together. As a result of the fixed-point measurement and gamma plotter H surface measurements, space dose rate from the first survey to the 11th survey shows the downward trend. We consider that there is no movement of radioactive pollutants from outside decontamination model project area into decontamination model project area.
Takahara, Shogo; Watanabe, Masatoshi; Oguri, Tomomi; Kimura, Masanori; Hirouchi, Jun; Munakata, Masahiro; Homma, Toshimitsu
JAEA-Data/Code 2016-016, 65 Pages, 2017/02
We surveyed on structural and material data on 22 facilities which are listed in local disaster management plan in Matsue city. These facilities can be divided into educational facilities, communal facilities and gymnastic hall. Height and floor-area of rooms, as well as window-area were collected as the structural data. We also collected information on constructional materials, and density of those. In addition, mass-thicknesses of the constructional materials were evaluated based on our surveys, and compared to the previous studies which were made in Japan, U.S., and European countries. Consequently, it was found that there is no significant difference of mass-thickness of constructional materials between the results of our surveys and the previous studies. However, for gymnastic hall, since thin metal plates are used for roofs, we can point out that the mass-thickness of roofs are much lower than those for other concrete facilities and clay tile roofing wooden houses.
Okajima, Satoshi; Wakai, Takashi; Ando, Masanori; Inoue, Yasuhiro*; Watanabe, Sota*
Journal of Pressure Vessel Technology, 138(5), p.051204_1 - 051204_6, 2016/10
Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Takeyasu, Masanori; Mizutani, Tomoko; Isozaki, Tokuju*; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; et al.
JAEA-Review 2015-034, 175 Pages, 2016/03
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2014 to March 2015. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co. in March 2011.
Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03
The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.
Koshimizu, Masanori*; Iwamatsu, Kazuhiro*; Taguchi, Mitsumasa; Kurashima, Satoshi; Kimura, Atsushi; Yanagida, Takayuki*; Fujimoto, Yutaka*; Watanabe, Kenichi*; Asai, Keisuke*
Journal of Luminescence, 169(Part B), p.678 - 681, 2016/01
We analyzed the effects of linear energy transfer (LET) on the scintillation properties of a Li glass scintillator, GS20. The scintillation time profiles were measured by using pulsed ion beams having different LETs. The rise in the scintillation time profiles was faster for higher LET, whereas the decay part was not significantly different for largely different LETs. The LET effects in the rise was ascribed to the effects of excited states interaction during the energy transfer process from the host glass to the luminescent centers, Ce ions. Supposing that the light yield decreases with LET, the fast rise at high LET was explained in terms of the competition between the energy transfer and the quenching due to the excited states interaction.
Maeyama, Shinya; Watanabe, Tomohiko*; Idomura, Yasuhiro; Nakata, Motoki; Nunami, Masanori*; Ishizawa, Akihiro*
Parallel Computing, 49, p.1 - 12, 2015/11
Maeyama, Shinya*; Idomura, Yasuhiro; Watanabe, Tomohiko*; Nakata, Motoki*; Yagi, Masatoshi; Miyato, Naoaki; Ishizawa, Akihiro*; Nunami, Masanori*
Physical Review Letters, 114(25), p.255002_1 - 255002_5, 2015/06
Multiscale gyrokinetic turbulence simulations with the real ion-to-electron mass ratio and value are realized for the first time, where the value is given by the ratio of plasma pressure to magnetic pressure and characterizes electromagnetic effects on microinstabilities. Numerical analysis at both the electron scale and the ion scale is used to reveal the mechanism of their cross-scale interactions. Even with the real- mass scale separation, ion-scale turbulence eliminates electron-scale streamers and dominates heat transport, not only of ions but also of electrons. When the ion-scale modes are stabilized by finite- effects, the contribution of the electron-scale dynamics to the turbulent transport becomes non-negligible and turns out to enhance ion-scale turbulent transport.
Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Takeyasu, Masanori; Mizutani, Tomoko; Isozaki, Tokuju; Morisawa, Masato; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; et al.
JAEA-Review 2014-042, 175 Pages, 2015/01
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2013 to March 2014. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Co. in March 2011.
Watanabe, Masahisa; Tagawa, Akihiro; Umemiya, Noriko; Maruyama, Noboru; Yoshida, Mami; Kawase, Keiichi; Noguchi, Shinichi; Sakazume, Yoshinori; Watanabe, Masanori; Hiraga, Hayato; et al.
JAEA-Review 2014-028, 184 Pages, 2014/10
JAEA received technical proposals from private enterprise about techniques that can be used for decontamination work, and "Decontamination Technology Demonstrations Projects" was commissioned from the Ministry of the Environment to verifies the decontamination effect, economy feasibility, safety, and other factors. By the "FY 2013 Decontamination Technology Demonstrations Projects" JAEA carried out technical advice of demonstration test and evaluation of 11 technologies (e.g., decontamination of soils and green space and wastes and washing of fly ash).
Ando, Masanori; Hirose, Yuichi*; Karato, Takanori*; Watanabe, Sota*; Inoue, Osamu*; Kawasaki, Nobuchika; Enuma, Yasuhiro*
Journal of Pressure Vessel Technology, 136(4), p.041406_1 - 041406_10, 2014/08
To compare and assess the creep-fatigue life evaluation methods for stress concentration point, a series of creep-fatigue test was performed with notched specimens made of Mod.9Cr-1Mo steel. Mechanical creep-fatigue tests and thermal creep-fatigue test were performed. A series of Finite Element Analysis was also carried out to predict the number of cycles to failure by the several creep-fatigue life evaluation methods. Then these predictions were compared with the test results. Several types of evaluation methods such are stress redistribution locus (SRL) method, simple elastic follow-up method and the methods described in the JSME FRs code were applied. Through the comparisons, it was appeared that SRL method gave rational conservative prediction of the creep-fatigue life for all conditions tested in this study. The JSME FRs code gave an evaluation over 70 times conservative lives comparing with the test results.