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Kobayashi, Hidekazu; Kodaka, Akira; Iwabuchi, Hiroki
no journal, ,
In JAEA's Tokai Vitrification Facility (TVF) at Tokai Reprocessing Plant (TRP) site, high level liquid waste (HLLW) generated from reprocessing of spent fuels is vitrified with a liquid-fed joule-heated ceramic melter (LFCM). As noble metals (NMs) in HLLW aren't soluble to the glass, and have low resistivity and higher density, they deposit on bottom of melter and form electrical path and thus disturb melter operation. The first and second TVF melter have square pyramidal shaped bottom and issue that NMs on the bottom are difficult to drain out and have to be removed periodically. To solve this issue, we are developing the third melter with conical shaped bottom. The effect of changing the bottom structure was confirmed by thermo-fluid analysis code. Structural optimization of strainer in the upper part of drain nozzle was carried out by visualization experiment. In this meeting, activity of third melter development including past melter structure will be introduced.
Ayame, Yasuo; Iwabuchi, Hiroki; Omori, Eiichi; Miura, Nobuyuki
no journal, ,
Tokai Reprocessing Plant (TRP) is preparing for decommissioning and dismantling, and it takes decades for completion. As about 360 m
of HLLW in TRP has risk of evaporation and hydrogen explosion, it must be controlled safely by keeping forced cooling and hydrogen exhausting. So, it was decided to vitrify in Tokai Vitrification Facility (TVF) by 2028 to reduce the risk. TVF was constructed in 1992 and vitrified 306 canisters until now. Full remote maintenance system is adopted for vitrification melter and HLLW tank in the cell. As noble metals in HLLW accumulate at bottom of melter, the melter must be emptied periodically and the noble metals must be removed with mechanical device. For the success of the vitrification, it is necessary to maintain the equipment by organized maintenance plan considering its aging, to expand the capacity to store canisters and to replace the melter within its design life. In this meeting, vitrification plan at Tokai site will be introduced.
Sato, Fuminori; Mori, Masahiro*; Arai, Tsuyoshi*; Saito, Yasuo
no journal, ,
The result of fused glass solidification test (waste packing ratio, etc.) using simulated waste liquid includes the tracer components based on analysis results of the radioactive liquid waste are reported.
Goto, Takahiro*; Matsubara, Ryuta*; Hamamoto, Takafumi*; Fujisaki, Kiyoshi*; Mitsui, Seiichiro; Taniguchi, Naoki
no journal, ,
To improve long-term glass corrosion model, immersion tests with specimens of carbon steel and simulated waste glass were conducted at 50
C and 80C under nitrogen gas atmosphere for 131 days. Control tests with a specimen of carbon steel or glass under the same conditions were also conducted. After the tests, the element concentration in the solution was analyzed to determine glass corrosion rates. We also analyzed the surface of specimens with XRD and TEM/ED (electron diffraction)/EDX to identify secondary phases. Glass corrosion rates for the tests with specimens of carbon steel and glass were two times larger than those for the control tests with glass specimen. With XRD and TEM/ED/EDX, we determined iron silicates on the surface of both carbon steel and glass. These observations are consistent with the results of geochemical calculation and published studies. The results indicate that glass corrosion could be enhanced by the precipitation of iron silicates.
Ishio, Takahiro*; Kanehira, Norio*; Hoshino, Takeshi*; Fukui, Toshiki*; Iwabuchi, Hiroki; Tsukada, Takeshi*
no journal, ,
In Japan, the High Level radioactive Liquid Waste (HLLW) generated along with the nuclear fuel cycle is to be vitrified, and its vitrification technology has been made practicable. And, various kinds of Low Level radioactive Liquid Waste (LLW) generated from reprocessing plant and nuclear power plants in Japan have been primarily treated by various methods such as incineration, compaction, cement solidification, however, vitrification method have not been introduced. On the other hand, there is a potential generation of LLW which has relatively high radioactivity level in case of conducting the decommissioning of reprocessing plant and nuclear power plants. Therefore, various kinds of the solidification and the volume reduction technologies have been developed in order to ensure the stable forms with smaller volumes for the LLW disposal. Furthermore, if the foundation for LLW vitrification technology is developed, it can be reflected in the advancement of vitrification technology of HLLW. Therefore, the Ministry of Economy, Trade and Industry launched the project "Basic Research Programs of Vitrification Technology for Waste Volume Reduction" during FY 2014 - 2018. IHI Corporation (IHI), Japan Nuclear Fuel Limited (JNFL), Japan Atomic Energy Agency (JAEA) and Central Research Institute of Electric Power Industry (CRIEPI) have commissioned this project. The development goals for this project are as follows. (1) To develop LLW generated at nuclear power plants and reprocessing plant, etc., to reinforce the foundation of vitrification technology for high volume reduction and more stable waste. (2) To study also advanced improvement of vitrification of HLLW that is practically used in Japan, by reflecting the findings obtained from LLW infrastructures. In this presentation we will report on our past achievements and future plans in this project.
Kofuji, Hirohide; Watanabe, So; Oyama, Koichi; Sasage, Kenichi
no journal, ,
Vitrification procedure for extraction chromatography using porous silica particles covered with extractant was investigated. In this method, minor actinides (MAs) were separated from high-level radioactive liquid waste by extractant CMPO and/or HDEHP. In this study, thermal degradation behavior and vitrification properties were evaluated from the viewpoints of high-level waste form properties using porous silica adsorbent impregnated with extractant CMPO. As the results of various experiments, suitable vitrification procedure for MA/RE adsorbents was clarified and selected adsorbent was generally well-vitrified and had enough chemical durability.