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JAEA Reports

Clearance of concrete generated from modification activities of JRR-3; Results for measuring and evaluating radioactivity concentration

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

JAEA-Technology-2017-017.pdf:15.97MB

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.

Journal Articles

Expansion control for cementation of incinerated ash

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

Journal Articles

Phase behavior and reverse micelle formation in supercritical CO$$_{2}$$ with DTAB and F-pentanol for decontamination of radioactive wastes

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$$_{2}$$ (scCO$$_{2}$$) solvent for the decontamination process of radioactive wastes, the reverse micelle formation in scCO$$_{2}$$ 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$$_{2}$$ were used. The reverse micelles could be formed by using 0.02 mol/dm$$^{3}$$ DTAB and 0.45 mol/dm$$^{3}$$ F-pentanol. A water concentration dissolved in scCO$$_{2}$$ was increased with an increase of pressure, and 0.42 mol/dm$$^{3}$$ water, which was 3 times larger than that in the neat CO$$_{2}$$, could be dissolved in scCO$$_{2}$$ at 38 MPa. Moreover, 0.1 mol/dm$$^{3}$$ HNO$$_{3}$$ 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$$_{2}$$.

JAEA Reports

Cement solidification test for incinerated ash, 1; Fundamental solidification characteristics of incinerated ashes

Kawato, Yoshimi; Tomioka, Osamu; Takahashi, Kuniaki; Meguro, Yoshihiro; Sakamoto, Hiroyuki*; Haga, Kazuko*

JAEA-Technology 2010-013, 38 Pages, 2010/07

JAEA-Technology-2010-013.pdf:1.36MB

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$$^2$$. The compressive strength made from the BB was lower 1.47 N/mm$$^2$$ 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$$^2$$. 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.

Journal Articles

Some advanced technologies for low-level radioactive waste treatment in JAEA

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$$_2$$ 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.

Journal Articles

Extraction of uranium from simulated ore by the supercritical carbon dioxide fluid extraction method with nitric acid-TBP complex

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:24.25(Chemistry, Analytical)

Supercritical fluid extraction (SFE) method using supercritical CO$$_2$$ fluid containing a complex of HNO$$_3$$-tri-$$n$$-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.

Journal Articles

Application of supercritical fluid extraction to metal separation in the field of nuclear technology

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$$^3$$ was developed for supercritical CO$$_2$$ 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$$_2$$. 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$$_2$$ 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.

Journal Articles

Removal and recovery of uranium from solid wastes by supercritical carbon dioxide fluid leaching method

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$$_{2}$$ fluid leaching (SFL) method using supercritical CO$$_{2}$$ fluid containing a complex of HNO$$_{3}$$ - 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.

Journal Articles

Solvent effect in supercritical carbon dioxide extraction of metal ions

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$$_{2}$$ 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$$_{2}$$MQ$$^{+}$$ under the extraction condition examined.

Journal Articles

Recovery of alkali salt by supercritical fluid leaching method using carbon dioxide

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$$_2$$ were recovered with a mixed fluid of carbon dioxide, methanol and crown ether. The influence of crown ether for KCl and SrCl$$_2$$ 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.

Journal Articles

Development of radioactive waste treatment by Supercritical Fluid Leaching (SFL) method

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

Journal Articles

Supercritical CO$$_{2}$$ fluid leaching (SFL) of uranium from solid wastes using HNO$$_{3}$$-TBP complex as a reactant

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

Journal Articles

New method for the removal of uranium from solid wastes with supercritical CO$$_{2}$$ medium containing HNO$$_{3}$$-TBP complex

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:86.54(Nuclear Science & Technology)

no abstracts in English

Oral presentation

Dissolution of plutonium oxide in reversed micellar solution

Tomioka, Osamu; Shimojo, Kojiro; Naganawa, Hirochika; Meguro, Yoshihiro; Takahashi, Kuniaki

no journal, , 

no abstracts in English

Oral presentation

Separation and recovery of uranium from radioactive solid waste by supercritical carbon dioxide leaching method

Wada, Ryutaro*; Yamamoto, Seiichi*; Masuda, Kaoru*; Meguro, Yoshihiro; Tomioka, Osamu; Yamamoto, Ichiro*

no journal, , 

no abstracts in English

Oral presentation

Supercritical carbon dioxide extraction of uranium-phosphate compound

Meguro, Yoshihiro; Tomioka, Osamu; Dung, L. T. K.*; Takahashi, Kuniaki

no journal, , 

no abstracts in English

Oral presentation

Decontamination of radioactive waste by supercritical CO$$_2$$ fluid leaching method

Tomioka, Osamu

no journal, , 

no abstracts in English

Oral presentation

Dissolution of plutonium oxide in reversed micellar solution

Tomioka, Osamu; Shimojo, Kojiro; Naganawa, Hirochika; Meguro, Yoshihiro; Takahashi, Kuniaki

no journal, , 

no abstracts in English

Oral presentation

Supercritical carbon dioxide extraction of uranium from ore for uranium analysis

Meguro, Yoshihiro; Tomioka, Osamu; Dung, L. T. K.*; Takahashi, Kuniaki

no journal, , 

no abstracts in English

Oral presentation

Degradation of nitrate ion by reduction using precious metal catalyst

Meguro, Yoshihiro; Tomioka, Osamu; Kato, Atsushi*

no journal, , 

no abstracts in English

41 (Records 1-20 displayed on this page)