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Asahi, Yoshimitsu; Fukuda, Shigeki; Shiramizu, Daiki; Miyata, Koshi; Tone, Masaya; Katsuoka, Nanako; Maeda, Yuta; Aoyama, Yusuke; Niitsuma, Koichi; Kobayashi, Hidekazu; et al.
JAEA-Technology 2024-024, 271 Pages, 2025/03
JAEA-Technology-2024-024.pdf:33.98MB
JAEA-Technology-2024-024-hyperlink.zip:31.96MB
A glass melter for the vitrification process of highly active liquid waste in the Tokai Reprocessing Plant, TVF's 3rd melter, was built, and the glass of 18 vitrified waste canisters in weight was melted and poured through a cold test operation. The molten glass surface was covered by a cold cap from feeding fiberglass cartridges saturated with non-radioactive simulant liquid waste as raw material, whose components are equivalent to actual waste. Differences in inherent characteristics of the thermal behavior between the 2nd and the 3rd melter due to the difference in design were considered to establish the procedure to control the new melter. The melter's condition was stabilized at a higher glass temperature and the cooling of 1 kW less in each of the two main electrodes, compared to the 2nd one. Under 39 kW joule heating of the main electrodes with 26 Nm3/h coolant flow rate, it showed the capability to finish heating the bottom furnace in 5 hours before pouring, 2 hours shorter than the 2nd melter. Measurements of the temperature distributions in molten glass and casing surface yielded data that is efficient for developing a simulation model. After Platinum Group Elements (PGE) concentration saturates in the molten glass, feeding raw material and discharging glass were suspended to examine a holding state, indicating PGE settling could retard. During the holding test, observation of the melting process of the cold cap declared that the surface was covered by a thin layer with almost non-fluidity. It will be a reason for choosing the no-slip condition of a fluid calculation, even in the hot-top condition. The investigation of PGE discharging behavior by analyzing the elemental composition of poured glass showed the accumulated PGE amount in the 3rd melter is small compared to the 2nd melter. Inspection of the melter inside after draining out concluded that there were neither significant residual glass nor refractory fragments.
Asahi, Yoshimitsu; Shimamura, Keisuke*; Kobayashi, Hidekazu; Kodaka, Akira
JAEA-Technology 2021-026, 50 Pages, 2022/03
JAEA-Technology-2021-026.pdf:6.29MB
In Tokai Reprocessing Plant, the highly active liquid waste derived from a spent fuel reprocessing is vitrified with a Liquid-Fed Ceramic Melter (LFCM) embedded in Tokai Vitrification Facility (TVF). For an LFCM, the viscosity of melted glass is increased by the deposition of oxidation products of platinum group elements (PGE) and the PGE-containing glass tends to settle to the melter's bottom basin even after draining glass out. Removal of the PGE-containing glass is needed to avoid the Joule heating current from being affected by the glass, it requires time-consuming work to remove. For the early accomplishment of vitrifying the waste, Japan Atomic Energy Agency is planning to replace the current melter with the new one in which the amount of PGE sediments would be reduced. In the past design activities for the next melter, several kinds of shapes in regard to the furnace bottom and the strainer were drawn. Among these designs, the one in which the discharge ratio of PGE-containing glass would be as much as or greater than the current melter and which be able to perform similar operational sequences done in the current melter is selected here. Firstly, an operational sequence to produce one canister of vitrified waste is simulated for three melter designs with a furnace bottom shape, using 3D thermal-hydraulic calculations. The computed temperature distribution and its changes are compared among the candidate structures. After discussions about the technical and structural feasibilities of each design, a cone shape with a 45
slope was selected as the bottom shape of the next melter. Secondly, five strainer designs that fit the bottom shape above mentioned are drawn. For each design, the fluid drag and the discharge ratio of relatively high viscosity fluid resting near the bottom are estimated, using steady or unsteady CFD simulation. By draining silicone oil from acrylic furnace models, it was confirmed experimentally that there are no vortices
Hayashi, Kimio; Nakagawa, Tetsuya; Onose, Shoji; Ishida, Takuya; Nakamichi, Masaru; Katsuyama, Kozo; Iwamatsu, Shigemi; Hasegawa, Teiji; Kodaka, Hideo; Takatsu, Hideyuki; et al.
JAEA-Technology 2009-007, 168 Pages, 2009/03
JAEA-Technology-2009-007.pdf:31.88MB
In-pile functional tests of breeding blankets have been planned by Japan Atomic Energy Agency (JAEA), using a test blanket module (TBM) which will be loaded in the International Thermonuclear Experimental Reactor (ITER). In preparation for the in-pile functional tests, JAEA has been being performed irradiation experiments of lithium titanate (Li
TiO
), which is the first candidate of solid breeder materials for the blanket of the demonstration reactor (DEMO) under designing in Japan. The present report describes (1) results of a detailed design and trial fabrication tests of a dismantling apparatus for irradiation capsules which were used in irradiation experiments by the Japan Materials Testing Reactor (JMTR) of JAEA, and (2) results of a preliminary investigation of a glove box facility for post-irradiation examinations (PIEs). In the detailed design of the dismantling apparatus, datailed specifications and the installation methods were examined, based on results of a conceptual design and basic design. In the trial fabrication, cutting tests were curried out by making a mockup of a cutting component. Furthermore, a preliminary investigation of a glove box facility was carried out in order to secure a facility for PIE work after the capsule dismantling, which revealed a technical feasibility.
Kuboki, Michikatsu; Naito, Masakazu; Sumi, Hirotaka; Nakayama, Jiro; Kano, Shigeru; Niitsuma, Koichi; Kodaka, Akira; Fujiwara, Koji
no journal, ,
no abstracts in English
Yamashita, Teruo; Matsumura, Tadayuki; Oyama, Koichi; Harashima, Takero; Ayame, Yasuo; Kodaka, Akira
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no abstracts in English
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.
Asahi, Yoshimitsu; Kodaka, Akira
no journal, ,
In the glass production of TVF melter, as raw material, fiberglass frit cartridges saturated with HAW are supplied to the melter. A lot of in-melting cartridges float on the molten glass surface and form a layer called cold-cap. A simulation model of the cold-cap, which enables reproduction of temperature distribution was developed. The cold-cap was modeled as a two-phase flow of cartridges and molten glass with fluid-particle interaction. The increasing of the apparent viscosity and the decreasing of joule heat current and thermal conductivity caused by floating cartridges are defined as a function of the concentration of solid particles. By involving these models simultaneously, a simulation in regard to an operation during glass production for the 2nd melter in TVF yields a slow fluid velocity at the cold-cap region and reproduced a thermally isolated layer, and the change of temperature observed at the bottom side of the cold-cap.
Aoyama, Yusuke; Tone, Masaya; Shiramizu, Daiki; Katsuoka, Nanako; Miyata, Koshi; Fukuda, Shigeki; Otaka, Hikaru; Kobayashi, Hidekazu; Kodaka, Akira
no journal, ,
In the new glass melter (the 3rd melter) at the Tokai Vitrification Facility (TVF), the bottom shape of the melter was changed from the square pyramid of the existing melter (the 2nd melter) to a cone to improve ability to discharge platinum group elements. To confirm the effect of the improvement, operational test using non-radioactive simulant of liquid waste containing platinum group elements was carried out. Discharging behavior of platinum group elements was evaluated in comparison with the 2nd melter.
Tone, Masaya; Shiramizu, Daiki; Katsuoka, Nanako; Aoyama, Yusuke; Miyata, Koshi; Fukuda, Shigeki; Otaka, Hikaru; Kobayashi, Hidekazu; Kodaka, Akira
no journal, ,
The replacement of existing 2nd glass melter with the 3rd glass melter is scheduled from 2025 to 2026 in Tokai Vitrification Facility, TVF. The bottom shape of 3rd melter was changed from the square pyramid of 2nd melter to a cone to improve ability to discharge platinum group elements. Therefore, it is necessary to confirm operational parameters appropriate for the 3rd melter with cone shaped bottom. Operational test using non-radioactive simulant of liquid waste was carried out to ensure the appropriate operational parameters that accommodate key control values such as glass temperature.
Kato, Junya; Nakazaki, Katsutoshi; Takaya, Akikazu; Matsumura, Tadayuki; Niitsuma, Koichi; Kodaka, Akira; Fujiwara, Koji
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Sumi, Hirotaka; Nakayama, Jiro; Kuboki, Michikatsu; Kodaka, Akira; Fujiwara, Koji
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Sumi, Hirotaka; Makigaki, Hikaru; Nakayama, Jiro; Niitsuma, Koichi; Kodaka, Akira
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Harashima, Takero; Yamashita, Teruo; Matsumura, Tadayuki; Oyama, Koichi; Ayame, Yasuo; Kodaka, Akira
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no abstracts in English
Matsumura, Tadayuki; Yamashita, Teruo; Oyama, Koichi; Harashima, Takero; Ayame, Yasuo; Kodaka, Akira
no journal, ,
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Oyama, Koichi; Matsumura, Tadayuki; Harashima, Takero; Yamashita, Teruo; Ayame, Yasuo; Kodaka, Akira
no journal, ,
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Asahi, Yoshimitsu; Shimamura, Keisuke; Kobayashi, Hidekazu; Kodaka, Akira; Morikawa, Yo
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Shimamura, Keisuke; Asahi, Yoshimitsu; Kobayashi, Hidekazu; Kodaka, Akira; Morikawa, Yo
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Matsumura, Tadayuki; Takaya, Akikazu; Sumi, Hirotaka; Ishii, Kiyonori; Niitsuma, Koichi; Kodaka, Akira; Fujiwara, Koji
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Nakayama, Jiro; Sumi, Hirotaka; Kuboki, Michikatsu; Kodaka, Akira; Fujiwara, Koji
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no abstracts in English