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Ogoshi, Yurie; Satoyama, Tomonori; Kishimoto, Katsumi; Nanri, Tomohiro; Suzuki, Takeshi; Tomioka, Osamu; Takaizumi, Hirohide*; Kanno, Tomoyuki*; Maruyama, Tatsuya*
JAEA-Technology 2017-017, 152 Pages, 2017/08
At Nuclear Science Research Institute, clearance works for about 4,000 tons of extremely low-level radioactive concrete debris, which were generated from the modification activities of JRR-3 from FY 1985 to FY 1989 and stored in the waste storage facility NL, carried out. First of this clearance works, method for measuring and evaluating radioactivity concentration was approved by Minister of MEXT on July 25, 2008. And then, clearance works were started from FY 2009. Measuring and evaluating radioactivity concentration was achieved by using the approved method, and was confirmed by government. And then, clearance works were completed in FY 2014. The clearance concrete was recycled as a material for restoration works of the 2011 off the Pacific coast of Tohoku Earthquake. This report summarizes the results of measuring and evaluating radioactivity concentration, achievement of confirmation by government, recycling of cleared concrete and cost for clearance works.
Nakayama, Takuya; Suzuki, Shinji; Hanada, Keiji; Tomioka, Osamu; Sato, Junya; Irisawa, Keita; Kato, Jun; Kawato, Yoshimi; Meguro, Yoshihiro
Proceedings of 2nd International Symposium on Cement-based Materials for Nuclear Wastes (NUWCEM 2014) (CD-ROM), 12 Pages, 2014/06
Kurahashi, Kensuke; Tomioka, Osamu; Meguro, Yoshihiro
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.217 - 220, 2011/01
To develop a metal separation method using supercritical CO (scCO
) solvent for the decontamination process of radioactive wastes, the reverse micelle formation in scCO
was investigated. Dodecyltrimethylammonium bromide (DTAB) as a surfactant to form the reverse micelles and 2,2,3,3,4,4,5,5-octafluoro-1-pentanol (F-pentanol) as a modifier to increase the solubility of DTAB into scCO
were used. The reverse micelles could be formed by using 0.02 mol/dm
DTAB and 0.45 mol/dm
F-pentanol. A water concentration dissolved in scCO
was increased with an increase of pressure, and 0.42 mol/dm
water, which was 3 times larger than that in the neat CO
, could be dissolved in scCO
at 38 MPa. Moreover, 0.1 mol/dm
HNO
could dissolve at the same pressure as water. On the other hand, it was found that the solubility of water at outside of reverse micelles increased with F-pentanol. The ratio of water and F-pentanol affected the phase behavior of water in scCO
.
Kawato, Yoshimi; Tomioka, Osamu; Takahashi, Kuniaki; Meguro, Yoshihiro; Sakamoto, Hiroyuki*; Haga, Kazuko*
JAEA-Technology 2010-013, 38 Pages, 2010/07
It is important to understand fundamental solidification characteristics of incinerated ashes of combustible and poorly combustible wastes generated by JAEA. Simulated solidified substances using incinerator fly ash were prepared under different conditions such as solidified materials, ash filling rates, amount of solidification retarders and so on. The compressive strength of the solidified substances prepared using a normal portland cement (OPC), a blast furnace slag cement (BB), and a low alkalinity cement (LAC) exceeded a standard value, 1.47 N/mm. The compressive strength made from the BB was lower 1.47 N/mm
when the filling rate of the incinerated ash was 40%. For the substances using the LAC, all the strengths were over 1.47 N/mm
. Pb and Zn would behave as retardative substances for solidification. All substances showed the compressive strength with the BB or the LAC. As insolubilizers for heavy metals, ferrous sulfate and sodium sulfide prevented Cr from elution.
Meguro, Yoshihiro; Tomioka, Osamu; Yamaguchi, Hiromi; Takahashi, Kuniaki
Proceedings of International Symposium on EcoTopia Science 2007 (ISETS '07) (CD-ROM), p.1043 - 1046, 2007/11
In order to lower the cost of the disposal of low-level radioactive waste, several waste treatment technologies, such as reduction of radioactive concentration in the waste, reduction in amount of the waste, and removal of harmful materials for the disposal, are essential. The authors have developed four waste treatment technologies; these are a supercritical CO fluid decontamination method, a calcination method, a chemical reductive denitration method, and a steam reforming method in JAEA. It was demonstrated that these methods showed promise for the waste treatment.
Dung, L. T. K.*; Imai, Tomoki*; Tomioka, Osamu; Nakashima, Mikio; Takahashi, Kuniaki; Meguro, Yoshihiro
Analytical Sciences, 22(11), p.1425 - 1430, 2006/11
Times Cited Count:7 Percentile:22.81(Chemistry, Analytical)Supercritical fluid extraction (SFE) method using supercritical CO fluid containing a complex of HNO
-tri-
-butyl phosphate (TBP) as an extractant was applied to extract uranium from a several uranyl phosphate compounds and simulated uranium ores. Extraction method consisting of a static and a dynamic extraction processes was established and experimental condition such as pressure, temperature, and extraction time were optimized. It was found that uranium could be efficiently extracted from both of the uranyl phosphates and simulated ores by the SFE method and then it was demonstrated that SFE was useful as a pretreatment method for uranium analysis in ores.
Meguro, Yoshihiro; Tomioka, Osamu; Takahashi, Kuniaki; Wada, Ryutaro*; Yamamoto, Seiichi*; Fukuzato, Ryuichi*
Proceedings of 8th International Symposium on Supercritical Fluids (ISSF 2006) (CD-ROM), 6 Pages, 2006/11
A large-scale apparatus having a reaction vessel of ca. 4000 cm was developed for supercritical CO
leaching. An ultrasonic wave oscillator, stirring device, and piston compressor were equipped to the apparatus to enhance mass transfer rate of substances in supercritical CO
. A sea sand sample, an incinerated ash sample, and a porous alumina brick sample, in which uranium oxide was adsorbed, were prepared as simulated samples of radioactive wastes and uranium was tried to remove from these samples to supercritical CO
including nitric acid - tri-n-butyl phosphate complex as a reactant using the apparatus. By several times of the uranium separation, more than 99% of uranium was removed from the sea sand sample and the ash sample. When the mass transfer enhanced system was operated, it was confirmed that separation efficiency of uranium was improved and then 99% of uranium could be removed form the ash sample.
Meguro, Yoshihiro; Tomioka, Osamu; Imai, Tomoki*; Fujimoto, Shigeyuki*; Nakashima, Mikio; Yoshida, Zenko; Honda, Tadashi*; Koya, Fumio*; Kitamura, Nobu*; Wada, Ryutaro*; et al.
Proceedings of International Waste Management Symposium 2004 (WM '04) (CD-ROM), 8 Pages, 2004/03
Supercritical CO fluid leaching (SFL) method using supercritical CO
fluid containing a complex of HNO
- tri-n-butyl phosphate (TBP) was applied to removal of uranium from radioactive solid wastes. Sea sands, incineration ashes and porous alumina bricks were employed as matrixes of simulated solid wastes. Real radioactive incineration ash wastes and firebrick wastes were also subjected to the SFL treatment. It was found that uranium could be efficiently removed from both of the simulated wastes and real wastes by the SFL method. The removal efficiency of uranium from the real waste was lower than that from the corresponding artificial waste. About 1 g and 35 mg of uranium were recovered from 10 g of the real ash waste and 37 g of the real firebrick waste, respectively.
Meguro, Yoshihiro; Ogiyanagi, Jin*; Tomioka, Osamu; Imura, Hisanori*; Ohashi, Kozaburo*; Yoshida, Zenko; Nakashima, Mikio
Proceedings of 2nd International Symposium on Supercritical Fluid Technology for Energy and Environment Applications (Super Green 2003), p.175 - 179, 2004/00
One of the most attractive properties of SFE is that changing solvent properties by tuning pressure can control distribution behavior of a metal ion. Distribution ratio (D) of uranium(VI) and plutonium(IV) with tributyl phosphate (TBP) from a nitric acid solution and palladium(II) with 2-methyl-8-qunolinol (HMQ) from a hydrochloric solution were determined in SFE at various pressures. In the extraction system using TBP, a linear relationship between the logarithmic distribution ratio (log D) and the solubility parameter of CO was observed. The solubility parameter is difined based on the regular solution theory and is one of the parameters depending on the pressure. On the other hand, a linear relationship with a positive slope between log D and the solubility parameter was observed in the extraction system using HMQ. Most of the extractant was dissolved in the aqueous phase as H
MQ
under the extraction condition examined.
Watanabe, Takeshi*; Tsushima, Satoru*; Yamamoto, Ichiro*; Tomioka, Osamu; Meguro, Yoshihiro; Nakashima, Mikio; Wada, Ryutaro*; Nagase, Yoshiyuki*; Fukuzato, Ryuichi*
Proceedings of 2nd International Symposium on Supercritical Fluid Technology for Energy and Environment Applications (Super Green 2003), p.363 - 366, 2004/00
Recovery of salts by supercritical fluid leaching (SFL) method using carbon dioxide was experimentally studied. It was confirmed that LiCl was recovered with a mixed fluid of carbon dioxide and methanol, and KCl and SrCl were recovered with a mixed fluid of carbon dioxide, methanol and crown ether. The influence of crown ether for KCl and SrCl
extraction were found to increase in the order of 15-crown-5 (15C5)
18-crown-6 (18C6)
dicychlohexyl-18-crown-6 (DC18C6). It is expected that other salts can be recovered selectively with a mixed fluid of carbon dioxide, methanol and suitable crown ether.
Nagase, Yoshiyuki*; Masuda, Kaoru*; Wada, Ryutaro*; Yamamoto, Ichiro*; Tomioka, Osamu; Meguro, Yoshihiro; Fukuzato, Ryuichi*
Proceedings of 2nd International Symposium on Supercritical Fluid Technology for Energy and Environment Applications (Super Green 2003), p.254 - 257, 2004/00
no abstracts in English
Tomioka, Osamu*; Meguro, Yoshihiro; Iso, Shuichi; Yoshida, Zenko; Enokida, Yoichi*; Yamamoto, Ichiro*
Proceedings of International Solvent Extraction Conference 2002 (CD-ROM), p.1143 - 1147, 2002/00
no abstracts in English
Tomioka, Osamu*; Meguro, Yoshihiro; Iso, Shuichi; Yoshida, Zenko; Enokida, Yoichi*; Yamamoto, Ichiro*
Journal of Nuclear Science and Technology, 38(6), p.461 - 462, 2001/06
Times Cited Count:27 Percentile:85.28(Nuclear Science & Technology)no abstracts in English
Meguro, Yoshihiro; Tomioka, Osamu; Kato, Atsushi*
no journal, ,
no abstracts in English
Meguro, Yoshihiro; Kadowaki, Haruhiko; Kato, Atsushi; Tomioka, Osamu; Takahashi, Kuniaki
no journal, ,
no abstracts in English
Kadowaki, Haruhiko; Kato, Atsushi; Tomioka, Osamu; Meguro, Yoshihiro; Takahashi, Kuniaki
no journal, ,
We studied effects of Pd-Cu composition and support material on catalytic activity in the nitrate decomposition with Pd-Cu catalyst and hydrazine as a liquid reductant. It was found that Pd was alloyed with Cu in the Pd-Cu catalyst prepared by electroless deposition method and the Pd-Cu surface composition was strongly influenced by the support material. The Pd-Cu composition giving the maximal catalytic activity for decomposition of nitrate ion and nitrite ion as intermediate was determined in the denitration with the Pd-Cu loaded carbon catalysts. And also it was found that the catalytic activity varied according to the support material.
Tomioka, Osamu; Meguro, Yoshihiro; Takahashi, Kuniaki
no journal, ,
no abstracts in English
Kurahashi, Kensuke; Tomioka, Osamu; Meguro, Yoshihiro; Takahashi, Kuniaki
no journal, ,
The solubilization of nitrate solution in supercritical CO by reverse micelle formation was investigated. After placing surfactant, alcohol and nitrate solution into a high-pressure cell, CO
was introduced into the cell at high pressure. When the pressure was then raised above the cloud point pressure (CPP), the clear single phase was obtained. It means the nitrate solution was dissolved in supercritical CO
. The effect of nitrate concentration on the CPP values was discussed.
Tomioka, Osamu; Meguro, Yoshihiro
no journal, ,
no abstracts in English
Kurahashi, Kensuke; Tomioka, Osamu; Meguro, Yoshihiro; Takahashi, Kuniaki
no journal, ,
no abstracts in English