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Yokota, Akira; Seya, Manato; Sugawara, Satoshi; Ishikawa, Joji; Yokobori, Tomohiko
JAEA-Technology 2026-010, 73 Pages, 2026/07
JAEA-Technology-2026-010.pdf:17.11MB
The Advanced Volume Reduction Facilities (AVRF) were constructed to produce waste packages compatible with future near-surface disposal. The facilities primarily target low-level beta/gamma solid waste generated from the Nuclear Science Research Institute and other research facilities. The processing operations at the AVRF include dismantling, sorting, repackaging, supercompaction, melting and other treatments. Since operations commenced in 1999, approximately 10,000 units (equivalent to 200-liter drums) of waste have been processed as of the end of FY2018. The conduct of treatment operations and the stable operation of AVRF require proper maintenance and management of the Electricity and Machinery Unit, which include power distribution unit, air compressor unit, exhaust unit, gas supply units, drainage units, and other electromechanical units. Since these units were first put into operation, they have been appropriately maintained and operated, including routine inspections and repairs. Compiling the operational and maintenance records of the Electricity and Machinery Unit to date is considered important for ongoing operations. This paper reports on the operational and maintenance status of the Electricity and Machinery Unit.
Iketani, Shotaro; Suzuki, Takeshi; Yokobori, Tomohiko; Sugawara, Satoshi; Yokota, Akira; Kikuchi, Genta; Muraguchi, Yoshinori; Kitahara, Masaru; Seya, Manato; Kurosawa, Tsuyoshi; et al.
JAEA-Technology 2025-001, 169 Pages, 2025/08
JAEA-Technology-2025-001.pdf:14.22MB
The radioactive waste treatment facilities at the Nuclear Science Research Institute includes the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility. These three facilities come under the purview of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors, and are included under Class C of the act based on the seismic requirements specified in the Act. We assessed the seismic capacity of these three radioactive waste treatment facilities based on the current Building Standards Act, to verify whether they comply with the new regulatory requirements enforced by the Nuclear Regulation Authority (NRA) in the aftermath of the 2011 nuclear accident at the Fukushima Daiichi Nuclear Power Station operated by the Tokyo Electric Power Company. We found that the allowable stress of a few structural members used in the construction of the facilities did not meet the regulatory requirements. After studying the approval granted by the NRA for the construction plans, including the design and construction methods (design and construction plans) of the three facilities on March 5, 2021, we made aseismic reinforcement at these facilities between 2021 and 2022. This report presents an overview of the seismic design of these facilities and an outline of the aseismic reinforcement conducted, management system existing, safety measures adopted, and the preoperational inspections conducted at these facilities.
Kawahara, Takahiro; Suda, Shoya; Fujikura, Toshiki; Masai, Seita; Omori, Kanako; Mori, Masakazu; Kurosawa, Tsuyoshi; Ishihara, Keisuke; Hoshi, Akiko; Yokobori, Tomohiko
JAEA-Technology 2023-020, 36 Pages, 2023/12
JAEA-Technology-2023-020.pdf:2.79MB
We have been storing drums containing radioactive waste (radioactive waste packages) at waste storage facilities. We have been managing radioactive waste packages along traditional safety regulations. However, over 40 years has passed from a part of them were brought in pit-type waste storage facility L. Most of them are carbon steel 200 L drums, and surface of them are corroded. For better safety management, we started to take drums out from the pit and inspect them in FY 2019. After each inspection, we repair them or remove the contents of the drum and refill new drums if necessary. In this report, we will introduce the planning, the review of the plan, and the trial operation of this project.
Nakashio, Nobuyuki*; Osugi, Takeshi; Kurosawa, Shigenobu; Ishikawa, Joji; Hemmi, Ko; Iketani, Shotaro; Yokobori, Tomohiko
JAEA-Technology 2022-016, 47 Pages, 2022/08
JAEA-Technology-2022-016.pdf:2.23MB
The Nuclear Science Research Institute (NSRI) of the Japan Atomic Energy Agency (JAEA) started operation of the Advanced Volume Reduction Facilities (AVWF) for production of waste packages for disposal of low-level radioactive solid wastes (LLW). To clarify the operating conditions for homogenization of non-metallic LLW, preliminary tests were carried out using the plasma melting furnace of the non-metal melting unit. The fluidity of molten waste influences homogenization conditions of solidified products. It was clarified that the viscosity, which is determined by the chemical composition and the melting temperature, influence the fluidity of molten waste greatly through previous literature review and the small-scale melting tests. In the preliminary tests, the simulated waste with a cold tracer loaded in 200 L drums were melted. Using the waste chemical components (basicity, iron oxide concentration) as an experimental parameter, the homogeneity of the chemical components of the solidified product was investigated and the homogenization conditions of melting tests were examined. The retention ratio of the tracer in the molten bath was also confirmed. The viscosity of the molten wastes was measured and the correlation with homogeneity was examined. In addition, the technical requirements that should be concerned in advance for future actual operation were discussed.
Iketani, Shotaro; Yokobori, Tomohiko; Ishikawa, Joji; Yasuhara, Toshiyuki*; Kozawa, Toshiyuki*; Takaizumi, Hirohide*; Momma, Takeshi*; Kurosawa, Shingo*; Iseda, Hirokatsu; Kishimoto, Katsumi; et al.
JAEA-Review 2018-016, 46 Pages, 2018/12
JAEA-Review-2018-016.pdf:12.79MB
Japan Atomic Energy Agency (JAEA) adopts melting process for the waste processing and packaging method of radioactive miscellaneous solid waste in NSRI because melting process is effective in radioactivity evaluation, volume reduction, and stabilization treatment. Metal melting processing facilities, Incinerator, and Nonmetal melting processing facilities (hereinafter referred to as melting process facilities) have taken lots of safety measures, including measures for preventing the recurrence of the fire accidents. To exchange opinions and discuss the validity of these measures and so on with internal personnel and external experts, "Discussions on Melting Process Facilities" was held. As a document collection, this paper summarizes presentation materials of discussion meetings. Presentation materials describe "Outline of AVRF", "Safety measures in the melting facilities in WVRF", "Operation management of the melting facilities in WVRF", "Comparison of the past accident cases between facilities in and outside Japan and WVRF", and "Introduction of past accident cases and safety measures in other facilities from each committee".
Nakashio, Nobuyuki; Osugi, Takeshi; Iseda, Hirokatsu; Tohei, Toshio; Sudo, Tomoyuki; Ishikawa, Joji; Mitsuda, Motoyuki; Yokobori, Tomohiko; Kozawa, Kazushige; Momma, Toshiyuki; et al.
Journal of Nuclear Science and Technology, 53(1), p.139 - 145, 2016/01
Times Cited Count：1 Percentile：8.83(Nuclear Science & Technology)no abstracts in English
Kanazawa, Shingo; Osugi, Takeshi; Nakashio, Nobuyuki; Ishihara, Keisuke; Yokobori, Tomohiko; Okoshi, Minoru; Tokizawa, Takayuki; Nakayama, Shinichi; Kimura, Takeshi*
no journal, ,
no abstracts in English
Kikuchi, Genta; Ishihara, Keisuke; Nozaki, Masaki; Hirayama, Takatoshi; Nakayama, Yoshihiko; Yokobori, Tomohiko
no journal, ,
no abstracts in English
Osugi, Takeshi; Hanawa, Ritsu; Ito, Keisuke; Yokobori, Tomohiko; Kozawa, Kazushige; Akabori, Mitsuo; Okamoto, Yoshihiro; Meguro, Yoshihiro; Okoshi, Minoru
no journal, ,
By the addition of clay minerals during the incineration plant residues, indicating that the Cs concentration in the fly ash and fly ash amount is suppressed.
Kikuchi, Genta; Ishihara, Keisuke; Nozaki, Masaki; Hirayama, Takatoshi; Nakayama, Yoshihiko; Yokobori, Tomohiko
no journal, ,
no abstracts in English
Yokobori, Tomohiko; Osugi, Takeshi; Hanawa, Ritsu; Ito, Keisuke; Kozawa, Kazushige; Akabori, Mitsuo; Okamoto, Yoshihiro; Okoshi, Minoru
no journal, ,
no abstracts in English
Nakayama, Yoshihiko; Yoshida, Yoshihiro; Muraguchi, Yoshinori; Ishihara, Keisuke; Yokobori, Tomohiko; Sudo, Tomoyuki
no journal, ,
no abstracts in English
Osugi, Takeshi; Hanawa, Ritsu; Yokobori, Tomohiko; Kozawa, Kazushige; Akabori, Mitsuo; Okamoto, Yoshihiro; Okoshi, Minoru
no journal, ,
The number and distribution of exhaust particles from incineration process of a plant body were investigated for the purpose of carring out volume reduction of decontamination wastes such as a plant matter.
