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Nakashio, Nobuyuki*; Osugi, Takeshi; Kurosawa, Shigenobu; Ishikawa, Joji; Hemmi, Ko; Iketani, Shotaro; Yokobori, Tomohiko
JAEA-Technology 2022-016, 47 Pages, 2022/08
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
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".
Ishihara, Keisuke; Yokota, Akira; Kanazawa, Shingo; Iketani, Shotaro; Sudo, Tomoyuki; Myodo, Masato; Irie, Hirobumi; Kato, Mitsugu; Iseda, Hirokatsu; Kishimoto, Katsumi; et al.
JAEA-Technology 2016-024, 108 Pages, 2016/12
Radioactive isotope, nuclear fuel material and radiation generators are utilized in research institutes, universities, hospitals, private enterprises, etc. As a result, various low-level radioactive wastes (hereinafter referred to as non-nuclear radioactive wastes) are produced. Disposal site for non-nuclear radioactive wastes have not been settled yet and those wastes are stored in storage facilities of each operator for a long period. The Advanced Volume Reduction Facilities (AVRF) are built to produce waste packages so that they satisfy requirements for shallow underground disposal. In the AVRF, low-level beta-gamma solid radioactive wastes produced in the Nuclear Science Research Institute are mainly treated. To produce waste packages meeting requirements for disposal safely and efficiently, it is necessary to cut large radioactive wastes into pieces of suitable size and segregate those depending on their types of material. This report summarizes activities of pretreatment to dispose of non-nuclear radioactive wastes in the AVRF.