Document collection of the 41st Technical Special Committee on Fugen Decommissioning

Koda, Yuya; Matsuno, Hiroki; Matsushima, Akira; Kubota, Shintaro; Toda, Keisuke; Nakamura, Yasuyuki

JAEA-Review 2024-003, 38 Pages, 2024/06

JAEA-Review-2024-003.pdf:4.94MB

"Fugen Decommissioning Engineering Center", in planning and carrying out our decommissioning technical development, organizes "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened domestic and international, as the central place in research and development base of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report consists of presentation paper are "The current status of Fugen decommissioning", "Regarding dismantling and decontamination of steam drums", "Knowledge of radiation management in dismantling contaminated equipment", "Achievements and considerations for identifying and separating contaminated parts of nonradioactive waste" and "Regarding technology development plans for nuclear reactor dismantling" which is presented in the 41st Technical Special Committee on Fugen Decommissioning.

Thermophysical properties of molten FeO, (FeO)-(ZrO) and (FeO)-(UO)

Kondo, Toshiki; Toda, Taro*; Takeuchi, Junichi*; Kargl, F.*; Kikuchi, Shin; Muta, Hiroaki*; Oishi, Yuji*

Journal of Nuclear Science and Technology, 59(9), p.1139 - 1148, 2022/09

https://doi.org/10.1080/00223131.2022.2032445

no abstracts in English

Separation factor of americium from cerium in molten chloride-liquid gallium reductive extraction system

Toda, Taro*; Maruyama, Takehiro*; Moritani, Kimikazu*; Moriyama, Hirotake*; Hayashi, Hirokazu

Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 77(8), p.649 - 651, 2009/08

https://doi.org/10.5796/electrochemistry.77.649

The distribution coefficients of Am and Ce were measured in the eutectic LiCl-KCl/liquid Ga system at 773K. By using ZrCl as the oxide ion scavenger in order to avoid the formation of such oxychlorides as MO, the effect of oxide ion concentration was well controlled on the distribution coefficients of Am and Ce. The separation factor between Am and Ce was then obtained to be about 100. By comparing the present value with the other experimental and the predicted ones, it was confirmed that the Ga system was more selective than the Bi and Cd system.

Thermodynamic properties of lanthanides and actinides for reductive ectraction of minor actinides

Toda, Taro*; Maruyama, Takehiro*; Moritani, Kimikazu*; Moriyama, Hirotake*; Hayashi, Hirokazu

Journal of Nuclear Science and Technology, 46(1), p.18 - 25, 2009/01

https://doi.org/10.3327/jnst.46.18

The excess thermodynamic quantities of lanthanides and actinides in molten salts and liquid metals were studied for reductive extraction of minor actinides. The excess enthalpies and entropies of those elements in the molten chloride phase were found to be correlated with the ionic radii of metal ions possibly due to complex formation. In the liquid metal phase, on the other hand, the excess enthalpies were explained with Miedema's atomistic model and the excess entropies were explained with the vibrational entropy due to alloy formation. Using these correlations and models, some missing values of the excess thermodynamic quantities were evaluated and the separation factors of minor actinides from lanthanides were calculated in different reductive extraction systems. The higher separation factors were obtained in the system using aluminum or gallium than in the system using bismuth or cadmium as the liquid metal phase.

Study on Thermal Electric Conversion System for Sodium cooled FBR; Investigation for development of thermoelectric materials and systematic technology

Suzuki, Ryosuke*; Tanabe, Kentaro*; kondo, koki*; Ono, Katsutoshi*; Toda, Shinichi; Kasagawa, Yusuke; Tamayama, Kiyoshi; Oketani, Kazuhiro*

JNC TY4400 2003-004, 214 Pages, 2003/08

JNC-TY4400-2003-004.pdf:19.93MB

Recently, it has been important to reuse discharged heat energy from present nuclear plants in the view of reduction of environmental burden and improvement of heat efficiency for plant. For practical use in future of sodium cooled FBRs, which are typical high temperature system, this issue must be given priority. The thermal electric conversion system has been applied to the limited uses such as space or military, however, that results show good merits for reliability, maintenance free, and so on. Recently, this technology has been reconsidered in the view of saving energy in general industry. In this study, we made an investigation for applicability of the thermal electric conversion system to sodium cooled FBR as a heat recovery techbnology. Exactly, We have carried out the fundamental research and development for thermoelectric materials and elements, development of modules, and sodium tests with those modules, and then, we acquired the fundamental knowledge to estimate the efficiencies of thermal electric conversion system or modules for a sodium cooled FBR.

Evaluation of labile Cs-137 in Fukushima rivers by diffusive gradients in thin films (DGT, 2; Examination in river basins

Tanaka, Takuro*; Saito, Takumi*; Toda, Kanako*; Fujiwara, Kenso; Terashima, Motoki; Nakanishi, Takahiro; Kobayashi, Natsuko*; Tanoi, Keitaro*

no journal, , 

Cs-137 dispersed by the Fukushima Daiichi Nuclear Power Plant accident deposited in Fukushima area, that are not decontaminated in mountainous areas, may migrate through river water to animals and plants. Most of Cs-137 in river are fixed in clay minerals, but there are some Cs that can be easily desorbed, named as labile components. It has been suggested that labile components affect the bioavailability of Cs-137. In this study, the labile Cs-137 was sampled in situ from upstream to downstream in several rivers of Fukushima using a passive sampler called diffusive gradients in thin films (DGT). Sampling was conducted at a different season in addition to the previous studies.