Nuclear disaster prevention based on lessons learned from the Fukushima Daiichi Nuclear Power Station accident

Shimada, Kazumasa; Nagai, Haruyasu; Hashimoto, Makoto; Iimoto, Takeshi*

Nihon Genshiryoku Gakkai-Shi ATOMO, 65(5), P. 290, 2023/05

https://doi.org/10.3327/jaesjb.65.5_290

This article is part of the special feature article "What should be done from now on after the 1F accident and what should be conveyed to the next generation after the 1F accident?" of the Atomic Energy Society of Japan, which summarizes the discussions and future proposals on nuclear disaster prevention in which the members of the Health Physics and Environment Science Subcommittee have been involved. In view of the recommendations of the Accident Investigation Committee of the Atomic Energy Society of Japan and the Meteorological Society of Japan, the behavior of radioactive plumes and the prediction of residents' evacuation behavior should be studied to support decision-making on evacuation and other protective measures for residents in and outside the UPZ. Furthermore, decision-making on protective measures and practical risk communication to residents based on radiation health risks to residents and ethical aspects are newly proposed.

Implementation of a low-activation Au-In-Cd decoupler into the J-PARC 1 MW short pulsed spallation neutron source

Teshigawara, Makoto; Ikeda, Yujiro; Oi, Motoki; Harada, Masahide; Takada, Hiroshi; Kakishiro, Masanori*; Noguchi, Gaku*; Shimada, Tsubasa*; Seita, Kyoichi*; Murashima, Daisuke*; et al.

Nuclear Materials and Energy (Internet), 14, p.14 - 21, 2018/01

https://doi.org/10.1016/j.nme.2018.02.001

We developed an Au-In-Cd (AuIC) decoupler material to reduce induced radioactivity instead of Ag-In-Cd one, which has a cut off energy of 1eV. In order to implement it into an actual moderator-reflector assembly, a number of critical engineering issues need to be resolved with regard to large-sized bonding between AuIC and A5083 alloys by the hot isostatic pressing process. We investigated this process in terms of the surface conditions, sizes, and heat capacities of large AuIC alloys. We also show a successful implementation of an AuIC decoupler into a reflector assembly, resulting in a remarkable reduction of radioactivity by AuIC compared to AIC without sacrificing neutronic performance.

Summary of instructor training program in FY2014 aiming at Asian countries introducing nuclear technologies for peaceful use (Contract program)

Hidaka, Akihide; Nakano, Yoshihiro; Watanabe, Yoko; Arai, Nobuyoshi; Sawada, Makoto; Kanaizuka, Seiichi*; Katogi, Aki; Shimada, Mayuka*; Ishikawa, Tomomi*; Ebine, Masako*; et al.

JAEA-Review 2016-011, 208 Pages, 2016/07

JAEA-Review-2016-011-01.pdf:33.85MB
JAEA-Review-2016-011-02.pdf:27.68MB

JAEA has been conducting the Instructor Training Program (ITP) since 1996 under the auspices of MEXT to contribute to human resource development in currently 11 Asian countries in the field of radiation utilization for seeking peaceful use of nuclear energy. ITP consists of Instructor Training Course (ITC), Follow-up Training Course (FTC) and Nuclear Technology Seminars. In the ITP, trainings or seminars relating to technology for nuclear utilization are held in Japan by inviting nuclear related people from Asian countries to Japan and after that, the past trainees are supported during FTC by dispatching Japanese specialists to Asian countries. News Letter is also prepared to provide the broad range of information obtained through the trainings for local people near NPPs in Japan. The present report describes the activities of FY2014 ITP and future challenges for improving ITP more effectively.

Work and safety managements for on-site installation, commissioning, tests by EU of quench protection circuits for JT-60SA

Yamauchi, Kunihito; Okano, Jun; Shimada, Katsuhiro; Omori, Yoshikazu; Terakado, Tsunehisa; Matsukawa, Makoto; Koide, Yoshihiko; Kobayashi, Kazuhiro; Ikeda, Yoshitaka; Fukumoto, Masahiro; et al.

JAEA-Technology 2015-053, 36 Pages, 2016/03

JAEA-Technology-2015-053.pdf:8.33MB

The superconducting Satellite Tokamak machine "JT-60SA" under construction in Naka Fusion Institute is an international collaborative project between Japan (JA) and Europe (EU). The contributions for this project are based on the supply of components, and thus European manufacturer shall conduct the installation, commissioning and tests on Naka site. This means that Japan Atomic Energy Agency (JAEA) had a quite difficult issue to manage the works by European workers and their safety although there is no direct contract. This report describes the approaches for the work and safety managements, which were agreed with EU after the tough negotiation, and then the completed on-site works for Quench Protection Circuits (QPC) as the first experience for EU in JT-60SA project. With the help of these approaches by JAEA, the EU works for QPC were successfully completed with no accident, and a great achievement was made for both EU and JA.

Demonstrative experiments on the migration of radiocesium from buried soil contaminated by the accident at Fukushima Daiichi Nuclear Power Station

Yamaguchi, Tetsuji; Shimada, Taro; Ishibashi, Makoto*; Akagi, Yosuke*; Kurosawa, Mitsuru*; Matsubara, Akiyoshi*; Matsuda, Yuki*; Sato, Shigeyoshi*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 22(2), p.21 - 27, 2015/12

https://doi.org/10.3327/jnuce.22.2_21

It is predictable from previous studies that radiocesium hardly migrate into surrounding soils and groundwater from soils contaminated by the Fukushima Daiichi Nuclear Power Plant accident if they are buried and covered with indigenous soils. This study demonstrated the prediction by performing in-situ migration experiments over a year in a public park in Miho, Ibaraki prefecture and in two public parks in Misato, Saitama prefecture. Contaminated soils were buried at a depth range of 0.3 - 1.0 m or at 0.3 - 1.3 m and covered with indigenous soil layer of 0.3 m, and were sprinkled with water to accelerate the radiocesium migration. Migration of radiocesium was not observed from radiometric analyses of boring cores and soil water samples. Laboratory column and sorption experiments revealed that the radiocesium hardly leach out of the soil and even if they leach out from the contaminated soil, radiocesium is sorbed on surrounding soils and hardly migrate through the soli layer. Simulation of Cs-137 migration for 100 years by an advection-diffusion model showed that Cs-137 hardly migrate and decay out in the contaminated soil.

Reference design of the power supply system for the resistive-wall-mode control in JT-60SA

Ferro, A.*; Gaio, E.*; Novello, L.*; Matsukawa, Makoto; Shimada, Katsuhiro; Kawamata, Yoichi; Takechi, Manabu

Fusion Engineering and Design, 98-99, p.1053 - 1057, 2015/10

https://doi.org/10.1016/j.fusengdes.2015.06.116

Design and realization of JT60-SA Fast Plasma Position Control Coils power supplies

Zito, P.*; Lampasi, A.*; Coletti, A.*; Novello, L.*; Matsukawa, Makoto; Shimada, Katsuhiro; Cinarelli, D.*; Portesine, M.*; Dorronsoro, A.*; Vian, D.*

Fusion Engineering and Design, 98-99, p.1191 - 1196, 2015/10

https://doi.org/10.1016/j.fusengdes.2015.05.069

Mechanisms of increasing of the magnetic alloy core shunt impedance by applying a transverse magnetic field during annealing

Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Yamamoto, Masanobu; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Toda, Makoto*; Yoshii, Masahito*

Nuclear Instruments and Methods in Physics Research A, 797, p.196 - 200, 2015/10

https://doi.org/10.1016/j.nima.2015.06.061

In the J-PARC synchrotrons, Magnetic Alloy (MA) cores loaded RF cavities are employed to achieve a high field gradient. We are successful to increase the shunt impedance of the MA cores for the Main Ring synchrotron RF cavities by applying a transverse magnetic field during annealing. The shunt impedances of the cores with transverse field annealing are around 50% higher than the cores without one. By applying the transverse magnetic field during annealing, the magnetization processes occur by mainly magnetization rotations, and consequently the core loss is reduced and the relative complex permeability shows an excellent frequency behavior. The MA core shunt impedance is increased by those improvements of the magnetic properties.

High intensity single bunch operation with heavy periodic transient beam loading in wide band RF cavities

Tamura, Fumihiko; Hotchi, Hideaki; Schnase, A.*; Yoshii, Masahito*; Yamamoto, Masanobu; Omori, Chihiro*; Nomura, Masahiro; Toda, Makoto*; Shimada, Taihei; Hasegawa, Katsushi*; et al.

Physical Review Special Topics; Accelerators and Beams, 18(9), p.091004_1 - 091004_8, 2015/09

https://doi.org/10.1103/PhysRevSTAB.18.091004

The RCS in the J-PARC was originally designed to accelerate two high intensity bunches, while some of neutron experiments in the MLF and a muon experiment using MR beams require a single bunch operation mode. The beam intensity in the single bunch operation has been limited by longitudinal beam losses due to the rf bucket distortions by the wake voltage of the odd harmonics in the wide band MA cavities. We installed an additional rf feedforward system to compensate the wake voltages of the odd harmonics (h=1,3,5). The longitudinal beam losses during the single bunch acceleration disappeared with feedforward for the odd harmonics. We also confirmed that the beam quality in the single bunch acceleration are similar to that of the normal operation with two bunches. Thus, high intensity single bunch acceleration at the intensity of 2.310 protons per bunch has been achieved in the J-PARC RCS.

Study of shunt impedance of the FT3L magnetic alloy core

Nomura, Masahiro; Yamamoto, Masanobu; Shimada, Taihei; Tamura, Fumihiko; Omori, Chihiro*; Toda, Makoto*; Hasegawa, Katsushi*; Hara, Keigo*; Yoshii, Masahito*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1096 - 1110, 2015/09

http://www.pasj.jp/web_publish/pasj2015/proceedings/PDF/THP0/THP053.pdf

We are successful in increasing the shunt impedance of the MA cores by applying a transverse magnetic field during annealing. In this paper, we discuss the effects of transverse field annealing on the MA core shunt impedance by comparing two kinds of MA cores, those are the FT3M core that is annealed without any magnetic fields and the FT3L core that is annealed with a transverse magnetic field. We also discuss the shunt impedance of the MA core when the magnetization processes are governed by ideal magnetization rotations. To understand the ribbon thickness and the permeability dependences of the shunt impedance intuitively, we represent the shunt impedance as the resistance of the closed rectangular loop through which the eddy current flows.