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Yokoyama, Sumi*; Hamada, Nobuyuki*; Tsujimura, Norio; Kunugita, Naoki*; Nishida, Kazutaka*; Ezaki, Iwao*; Kato, Masahiro*; Okubo, Hideki*
International Journal of Radiation Biology, 99(4), p.604 - 619, 2023/04
Times Cited Count：2 Percentile：32.94(Biology)In April 2011, the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens. Such a new occupational lens dose limit has thus far been implemented in many countries, and there are extensive discussions toward its regulatory implementation in other countries. In Japan, discussions in the Japan Health Physics Society (JHPS) began in April 2013 and in Radiation Council in July 2017, and the new occupational lens dose limit was implemented into regulation in April 2021. To share our experience, we have published a series of papers summarizing situations in Japan: the first paper based on information available by early 2017, and the second paper by early 2019. This paper (our third paper of this series) aims to review updated information available by mid-2022, such as regarding regulatory implementation of the new occupational lens dose limit, recent discussions by relevant ministries based on the opinion from the council, establishment process of safety and health management systems, the JHPS guidelines on lens dose monitoring and radiation safety, voluntary countermeasures of the licensees, development of lens dose calibration method, and recent studies on exposure of the lens in nuclear workers and biological effect on the lens.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：5 Percentile：81.82(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Co radiation source under an intense 
Cs radiation field using an application-specific CeBr
spectrometer suited for use in intense radiation fieldsKaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Takahashi, Hiroyuki*
Journal of Nuclear Science and Technology, 59(8), p.983 - 992, 2022/08
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Yokoyama, Sumi*; Tsujimura, Norio; Hashimoto, Makoto; Yoshitomi, Hiroshi; Kato, Masahiro*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Sekiguchi, Hiroshi*; Koguchi, Yasuhiro*; Ono, Koji*; et al.
Journal of Radiation Protection and Research, 47(1), p.1 - 7, 2022/03
Background: In Japan, new regulations that revise the dose limit for the lens of the eye (the lens), operational quantities, and measurement positions for the lens dose were enforced in April 2021. Based on the international safety standards, national guidelines, the results of the Radiation Safety Research Promotion Fund of the Nuclear Regulatory Authority, and other studies, the Working Group of Radiation Protection Standardization Committee, the Japan Health Physics Society (JHPS) developed a guideline for radiation dose monitoring for the lens. Materials and Methods: The Working Group of the JHPS discussed the criteria of non-uniform exposure and the management criteria set to not exceed the dose limit for the lens. Results and Discussion: In July 2020, the JHPS guideline was published. The guideline consists of three parts: main text, explanations, and 26 questions. In the questions, the corresponding answers were prepared, and specific examples were provided to enable similar cases to be addressed. Conclusion: With the development of guideline on radiation dose monitoring of the lens, radiation managers and workers will be able to smoothly comply with revised regulations and optimise radiation protection.
Yokoyama, Sumi*; Iwai, Satoshi*; Tsujimura, Norio; Hashimoto, Makoto; Yoshitomi, Hiroshi; Kato, Masahiro*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Sekiguchi, Hiroshi*; Koguchi, Yasuhiro*; et al.
Proceedings of 15th International Congress of the International Radiation Protection Association (IRPA-15) (Internet), 8 Pages, 2022/00
-ray spectrometer and its performance under intense Cs and Co radiation fieldsKaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*
Nuclear Instruments and Methods in Physics Research A, 1010, p.165544_1 - 165544_9, 2021/09
Times Cited Count：0 Percentile：0.02(Instruments & Instrumentation)The number of nuclear facilities being decommissioned has been increasing worldwide, in particular following the accident of the Tokyo Electric Power Company Holdings' Fukushima Daiichi Nuclear Power Station in 2011. In these nuclear facilities, proper management of radioactive materials is required. Then, A -ray spectrometer with four segmentations using small volume CeBr
scintillators with a dimension of 
was developed. The four scintillators were coupled to a multi-anode photomultiplier tube specific to intense radiation fields. We performed the -ray exposure study under Cs and Co radiation fields. Under the Cs radiation field, the relative energy resolution at 1375 mSv/h was the relative energy resolution at 1375 mSv/h was 9.2
0.05%, 8.00.08%, 8.0
0.03%, and 9.00.04% for the four channels, respectively.
scintillator under intense -ray fields for nuclear decommissioningKaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research A, 988, p.164900_1 - 164900_8, 2021/02
Times Cited Count：11 Percentile：87.80(Instruments & Instrumentation)An increasing number of nuclear facilities have been decommissioned worldwide following the 2011 accident of the TEPCO' Fukushima Daiichi Nuclear Power Station. During the decommissioning, radioactive materials have to be retrieved under proper management. In this study, a small cubic CeBr spectrometer with dimensions of 5 mm 
5 mm 5 mm was manufactured to perform -ray spectroscopy under intense -ray fields. Furthermore, thanks to a fast digital process unit and a customized photomultiplier, the device could perform -ray spectroscopy at dose rates of over 1 Sv/h. The energy resolution (FWHM) at 662 keV ranged from 4.4% at 22 mSv/h to 5.2% at 1407 mSv/h for a Cs radiation field. Correspondingly, at 1333 keV, it ranged from 3.1% at 26 mSv/h to 4.2% at 2221 mSv/h for a Co radiation field, which suggested to realize -ray assessment of 
Cs, Cs, Co, and 
Eu at dose rates of over 1 Sv/h.
Minato, Kazuo; Akabori, Mitsuo; Tsuboi, Takashi; Kurobane, Shiro; Hayashi, Hirokazu; Takano, Masahide; Otobe, Haruyoshi; Misumi, Masahiro*; Sakamoto, Takuya*; Kato, Isao*; et al.
JAERI-Tech 2005-059, 61 Pages, 2005/09
JAERI-Tech-2005-059.pdf:20.67MB
An experimental facility called the Module for TRU High Temperature Chemistry (TRU-HITEC) was installed in the Back-end Cycle Key Elements Research Facility (BECKY) of the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) for the basic studies of the behavior of the transuranium elements (TRU) in pyrochemical reprocessing and oxide fuels. TRU-HITEC consists of three alpha/gamma cells shielded by steel and polyethylene and a glove box shielded by leaded acrylic resin, where experimental apparatuses have been equipped and a high purity argon gas atmosphere is maintained. In the facility 10 g of 
Am as well as the other TRU of Np, Pu and Cm can be handled. This report summarizes the outline, structure, performance and interior apparatuses of the facility, and is the result of the joint research between the Japan Atomic Energy Research Institute and three electric power companies of Tokyo Electric Power Co., Tohoku Electric Power Co. and the Japan Atomic Power Co.
Tsunematsu, Toshihide; Seki, Masahiro; Tsuji, Hiroshi; Okuno, Kiyoshi; Kato, Takashi; Shibanuma, Kiyoshi; Hanada, Masaya; Watanabe, Kazuhiro; Sakamoto, Keishi; Imai, Tsuyoshi; et al.
Fusion Science and Technology, 42(1), p.75 - 93, 2002/07
Times Cited Count：1 Percentile：9.91(Nuclear Science & Technology)Japanese contributions to ITER Engineering Design Activity are presented, together with an introduction of the objectives and design of the ITER whose program have been carried out through the international collaboration by EU, Japan, Russian Federation and the USA. New technologies have been produced through the development, fabrication and testing of scalable models in the fields of superconducting magnet, reactor structure with vacuum vessel, high-heat-flux plasma facing component, neutral beam injector, high-power mm-wave generator and so on. As major contributions from Japan, development and testing results of a 13-T, 640-MJ, NbSn pulsed magnet, a 18-degree sector of vacuum vessel with a height of 15 m and a width of 9 m, CFC armors to CuCrZr cooling tube that withstood 20 MW/m
, a 31 mA/cm negative ion beam source, a 1-MeV beam-accelerator, a 1-MW 170-GHz gyrotron were described.
Mori, Masahiro; Shoji, Teruaki; Araki, Masanori; Saito, Keiji*; Senda, Ikuo; Omori, Junji*; Sato, Shinichi*; Inoue, Takashi; Ono, Isamu*; Kataoka, Takahiro*; et al.
Nihon Genshiryoku Gakkai-Shi, 44(1), p.16 - 89, 2002/01
no abstracts in English
Seki, Masahiro; Hishinuma, Akimichi; Kurihara, Kenichi; Akiba, Masato; Abe, Tetsuya; Ishitsuka, Etsuo; Imai, Tsuyoshi; Enoeda, Mikio; Ohira, Shigeru; Okumura, Yoshikazu; et al.
Kaku Yugoro Kogaku Gairon; Mirai Enerugi Eno Chosen, 246 Pages, 2001/09
no abstracts in English
Hirano, Koichiro; Nomura, Masahiro; Yamazaki, Yoshio; ; ; ;
JNC TN9400 99-040, 52 Pages, 1999/05
The development of a high power CW electron linear accelerator was started in 1989 to study the feasibility of nuclear waste transmutation. The accelerator (10MeV, 100mA peak current, 4 ms pulse width, 50 Hz repetition) is dedicated machine for development of the high current acceleration technology in future need. It is necessary to develop the system which controls high power RF in order to stably accelerate the high current beam. Then, We have developed the interlock system for protecting accelerating tube from high current beam in time of trouble of high current beam and high power RF. We have succeeded in the development of the system so as to be able to choose interlock elements corresponding to the operating condition. Using the beam of the low electric power, the synthetic interlock system was tested. The beam was cut off at 3.5
sec, after the interlock operated.
Emoto, Takashi; Kato, Yuko*; Hirano, Koichiro; Ishikawa, Y.*; Takei, Hayanori; Nomura, Masahiro; Tani, Satoshi
PNC TN9410 98-060, 45 Pages, 1998/06
Design and construction of a high power cw (Continuous Wave) electron linac for studying feasibility of nuclear waste transmutation was started in 1989 at PNC. The PNC accelerator (10Mev, 20mA average current, 4 ms pulse width, 50 Hz repetition) is dedicated machine for development of the high current acceleration technology in future need. The computer control system is responsible for accelerator control and supporting the experiment for high power operation. The feature of the system is the measurements of accelerator status simultaneously and modularity of software and hardware for easily implemented for modification or expansion. The high speed network (SCRAMNet
15MB/s), Ethernet, and front end processors (Digital Signal Processor) were employed for the high speed data taking and control. The system was designed to be standard modules and software implemented man machine interface. Due to graphical-user-interface and object-oriented-programming, the software development environment is effortless programming and maintenance.
Nomura, Masahiro; Toyama, Shinichi; ; ;
PNC TN9410 92-213, 27 Pages, 1992/08
We are developing a test CW electron linac to develop a high power accelerator. In the key technology development, activity is focused on the developments of electron gun, klystron, and accelerator tube for high power RF. It is very important for a high power accelerator to develop an electron gun, because the beam current depends on electron gun. This paper presents the present status. We introduce in this paper the cathode material, the emission type, the accelerating field, and preliminary results of electron trajectories calculated by EGUN code.
-ray spectrometry system suited in high dose-rate radiation fields for use in non-destructive assay of nuclear fuel debrisKaburagi, Masaaki; Shimazoe, Kenji*; Kurosawa, Tadahiro*; Kato, Masahiro*; Takahashi, Hiroyuki*
no journal, ,
no abstracts in English
-ray spectrometry system specific to high dose-rate radiation fields for the retrieval of nuclear fuel debris in Tokyo Electrical Power Company Holdings' Fukushima Daiichi Nuclear Power StationKaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.
no journal, ,
The retrieval of nuclear fuel debris will be started at Tokyo Electrical Power Company Holdings' Fukushima Daiichi Nuclear Power Station. Because of high dose-rate fields on the surface of nuclear fuel debris and these inhomogeneous elements, non-destructive analysis is required during the retrieval. Here, it is presented that a -ray spectrometry system specific to high dose-rate fields was developed and its performance under intense -ray fields was evaluated for the retrieval of nuclear fuel debris.
-ray sepctrometry system for use at high dose ratesKaburagi, Masaaki; Takahashi, Hiroyuki*; Shimazoe, Kenji*; Kurosawa, Tadahiro*; Kato, Masahiro*
no journal, ,
no abstracts in English
