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Kozai, Naofumi; Sato, Junya; Osugi, Takeshi; Shimoyama, Iwao; Sekine, Yurina; Sakamoto, Fuminori; Onuki, Toshihiko
Journal of Hazardous Materials, 416, p.125965_1 - 125965_9, 2021/08
Times Cited Count：24 Percentile：85.21(Engineering, Environmental)Nakayama, Takuya; Kawato, Yoshimi; Osugi, Takeshi; Shimazaki, Takejiro; Hanada, Keiji; Suzuki, Shinji; Sakakibara, Tetsuro; Nakazawa, Osamu; Meguro, Yoshihiro
JAEA-Technology 2014-046, 56 Pages, 2015/03
JAEA-Technology-2014-046.pdf:7.61MB
The combustible and flame-retardant radioactive wastes generated as a result of the research activities in Japan Atomic Energy Agency (JAEA) are incinerating to reduce their volume. The incinerated ash is planned to be solidified using cement for disposal. Since the properties of ashes generated in each institute of JAEA are varied with the type of incinerator and the wastes to be incinerated, it is necessary to do fundamental solidification tests in each institute to decide operating conditions of the planning cement solidification facility. It is important to standardize evaluating methods of cement and solidified waste because some characters depend on measuring method. This user's guide have been prepared how to decide the cement solidifying conditions of ash to design the cement solidification facility in JAEA. Requirements on the regulations of solidified radioactive waste have been examined and seven technical criteria, e.g. compressive strength, fluidity, have been selected as characters to be evaluated. Some empirical notes about selection of cement, admixtures, procedure on making a test piece, evaluation of expanding, compressive strength, solubility have been described. The strategy of tests and tips for finding optimized solidification condition has been summarized. Finally the example of optimized conditions satisfied the requirements and some problems to be solved have been described.
Kozai, Naofumi; Suzuki, Shinichi; Aoyagi, Noboru; Sakamoto, Fuminori; Onuki, Toshihiko
Water Research, 68, p.616 - 626, 2015/01
Times Cited Count：20 Percentile：60.58(Engineering, Environmental)The radioactive fallout cesium (
Cs) in the sewage sludge ashes (SSAs) produced after the Fukushima Daiichi Nuclear Accident was tested. Two of tested five SSAs contained Cs above the radioactivity criterion for controlled landfill disposal in Japan. The minerals of SSAs are divided into two groups: an HCl-soluble phase mainly composed of phosphates and metal oxides; and silicates. The majority of Cs was contained in the HCl-soluble phase. Among the HCl-soluble subphases, Fe-bearing phases, probably iron oxides, were mainly responsible for Cs retention. Pre-pulverizing SSAs and heating them in an aqueous HCl was the most effective method of dissolving the HCl-soluble phase. The radioactivity concentrations of Cs in all the HCl-treatment residues were below the criterion. This residue was mostly composed of silicates. Static leaching tests of the residue revealed that Cs is very stably immobilized in the silicates.
Ishiyama, Takashi; Bamba, Tsunetaka; Mitamura, Hisayoshi; Maeda, Toshikatsu
Haikibutsu Gakkai Rombunshi, 12(2), p.82 - 86, 2001/03
no abstracts in English
Iwase, Masanori*
JNC TJ8400 2000-063, 78 Pages, 2000/03
JNC-TJ8400-2000-063.pdf:1.93MB
This study is aimed at controlling oxidation reaction of molten metal by ash in incineration systems, and at positively utilizing the oxidation reaction for decontamination of slag. In this year, in order to investigate physico-chemical properties of mixed fused salt containing alkali sulfates, with special focus on the behaviour of oxygen anion in the melts, Cu
/ Cu
redox equilibrium experiments were carried out. Among the effect of various parameters on Cu / Cu ratio in binary and ternary alkali sulfate melts, the effect of partial pressures of oxygen and SO
was mainly investigated in the study. Variation in Cu / Cu ratio were presented as the function of partial pressures of oxygen and SO, respectively. Possible thermodynamic interpretation were made on the experimental results. In addition, the dissolution of CrO
in mixed alkali sulfates were also investigated as a first step to elucidate the mechanism of hot corrosion. With this investigation, an important finding was obtained that the solubility of CrO for melts with same average ionic radius, in other words, oxygen ion activity, were essentially identical under constant temperature and atmosphere.
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solid Waste treatment facilities Conceptual design study*; Seki, Sadao*; *
PNC TJ9409 91-001, 164 Pages, 1991/02
This report describes the result of conceptual design study concerned with "High Radioactive - Solid Waste Treatment Facilities, "which will be planed for the purpose of volume reduction and stabilization of High Radioactive - solid wastes generated and stocked in the O-arai Engineering Center of PNC. In this conceptual design study the basic process of the facilities, which are sufficient to treat each waste and develop technologies, are clarified. This report consist with: (1)Clarification of waste to be treated. (2)Study on the treatment technology and process. (3)Conceptual design of facilities and equipment. (4)Estimation of construction cost and schedule.
combustible waste management system of JAERI-OARAI; ; Abe, Masayoshi
Hoken Butsuri, 26, p.47 - 58, 1991/00
no abstracts in English
、 Solid Wastes by Microwave Heating; *; ; ; ; ; *; *
JAERI-M 84-001, 76 Pages, 1984/02
no abstracts in English
Nakayama, Takuya; Suzuki, Shinji; Hanada, Keiji; Kawato, Yoshimi; Meguro, Yoshihiro
no journal, ,
no abstracts in English
Cs in sewage sludge ash and radioactivity concentration reduction methodKozai, Naofumi; Suzuki, Shinichi; Aoyagi, Noboru; Sakamoto, Fuminori; Onuki, Toshihiko
no journal, ,
Huge quantities of radionuclides were emitted by the accident at the Fukushima Daiichi Nuclear Power Plant and descended in wide areas of east Japan. A great amount of sewage sludge ashes (SSAs) containing fallout radionuclides (mainly Cs) at high concentration was generated and has been stored in sewage treatment plants until being disposed of. To contribute for the safety landfill disposal, we investigated the chemical states of Cs in SSAs by dissolution and static leach experiments. A fraction of Cs was contained in alkali metal salts, the major fraction of Cs was in iron oxides, and the rest was in silicates (quartz and feldspar). About 80-90% of Cs was contained in alkali metal salts and iron oxides and most of these solid phases were dissolved by heating in HCl aqueous solutions. These HCl-dissolvable phases were completely dissolved by pre-pulverizing SSAs and the subsequent heating in HCl aqueous solution at 95
C. The residues were mostly silicates and contained about 10-20% of Cs in the original SSAs. Several percent of Cs in the original SSA was leachable to synthetic seawater, while the Cs in the residue was non-leachable.
-ray irradiation, 3Nakayama, Takuya; Hanada, Keiji; Suzuki, Shinji; Kawato, Yoshimi; Meguro, Yoshihiro
no journal, ,
no abstracts in English
Takahashi, Nobuo; Sugitsue, Noritake; Yokoyama, Kaoru; Ohara, Yoshiyuki; Yanase, Shinichiro*; Kochi, Toshinori*; Takami, Toshihiro*; Kuwagi, Kenya*; Hyakutake, Toru*; Takeda, Hiroshi*; et al.
no journal, ,
As part of the cesium behavior analysis in the incineration plant, we carried out simulation by urban garbage of high cesium density incinerated. We chose plant having the results that burnt up contaminated urban garbage with radiocesium, as the object of the analysis.
Kozai, Naofumi; Suzuki, Shinichi; Sakamoto, Fuminori; Onuki, Toshihiko
no journal, ,
A fraction of radiocesium (Cs) released by the Fukushima Daiichi Nuclear Power Plant accident was accumulated in sewage sludge ash (SSA). It was previously reported that more than 80% of Cs is fixed in iron oxides of SSA and approximately 10% of Cs is tightly fixed in unidentified amorphous silicon oxides of SSA. This study reports that silicon in paper flowing in sewage and that in organic flocculant added to sewage at sewage treatment plants are origin of the silicon in SSA. Next, to contribute to developing measures for SSA disposal, we prepared geopolymer and cement solidified bodies containing SSA and evaluated their characteristics. We report a high barrier performance of geopolymer solidified bodies.
Koshino, Katsuhiko; Takano, Masato; Sato, Fuminori; Saito, Yasuo
no journal, ,
no abstracts in English
