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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.
Nagai, Takayuki; Hasegawa, Takehiko*
JAEA-Research 2023-008, 41 Pages, 2023/12
JAEA-Research-2023-008.pdf:7.52MB
To reduce the risks posed by stored the high-level radioactive liquid waste (HAW), Tokai Vitrification Facility (TVF) is working to produce the HAW into vitrified bodies. With the aim of steady vitrification of HAW in TVF, the vitrification technology section has manufactured a new 3rd melter with an improved bottom structure and is working to verify the performance of this melter. In this study, solidified glass samples were taken from simulated vitrified bodies produced by flowing molten glass during the bottom drain-out test in the operation confirmation of the TVF 3rd melter. And the properties of the surface layer and fracture surface of the vitrified bodies were evaluated by using Raman spectroscopy, synchrotron radiation XAFS measurement, and laser ablation inductively coupled plasma atomic emission spectroscopy (LA ICP-AES) analysis. As a result of measuring the surface layer and fracture surface of the solidified samples produced on an actual scale, a slight difference was confirmed between the properties of the surface layer and those of the fracture surface. Since the chemical composition of these simulated vitrified bodies does not contain platinum group elements, it is expected that the glass structure of solidified glass samples is different from that of the actual vitrified body. However, this sample measuring was a valuable opportunity to evaluate samples produced by using the direct energized joule heating method. The properties of cullet used the operation confirmation of the TVF 3rd melter and the cullet of another production lot were measured and analyzed in the same manner under the measuring conditions of solidified glass samples. As a result, it was confirmed that cullet with different producing histories have different glass structures even with the same chemical composition, and that differences in glass structures remain in the glass samples after melting these cullet.
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
Suzuki, Seima; Otaka, Hikaru; Usui, Yasufumi*; Morigaki, Yoshin*; Ito, Ryosuke*
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Yamauchi, Sho; Tokoro, Takeshi; Kuboki, Michikatsu; 9 of others*
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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
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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.
Asahi, Yoshimitsu; Nakajima, Masayoshi; Ayame, Yasuo
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Yamashita, Teruo; Matsumura, Tadayuki; Oyama, Koichi; Harashima, Takero; Ayame, Yasuo; Kodaka, Akira
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Shimamura, Keisuke; Asahi, Yoshimitsu; Kobayashi, Hidekazu; Kodaka, Akira; Morikawa, Yo
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Harashima, Takero; Yamashita, Teruo; Matsumura, Tadayuki; Oyama, Koichi; Ayame, Yasuo; Kodaka, Akira
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Oyama, Koichi; Matsumura, Tadayuki; Harashima, Takero; Yamashita, Teruo; Ayame, Yasuo; Kodaka, Akira
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Asahi, Yoshimitsu; Shimamura, Keisuke; Kobayashi, Hidekazu; Kodaka, Akira; Morikawa, Yo
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no abstracts in English