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Journal Articles

Preparation of Sr adsorptive fiber by impregnating with crown ether derivative for $$^{90}$$Sr measurement

Horita, Takuma; Asai, Shiho; Konda, Miki; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Kitatsuji, Yoshihiro

Bunseki Kagaku, 66(3), p.189 - 193, 2017/03

 Times Cited Count:0 Percentile:100(Chemistry, Analytical)

A Sr-selective adsorption fiber was prepared for rapid analysis of $$^{90}$$Sr content by using radiation-induced emulsion graft polymerization and subsequent chemical modification. A polyethylene fiber with a diameter of 13 $$mu$$m was first immersed in a methanol solution of an epoxy-group-containing vinyl monomer, glycidyl methacrylate (GMA), and polyoxyethylene sorbitol ester (Tween20) as a surfactant for graft-polymerization of GMA. Octadecylamine was then bound to a polymer chain extending from the fiber surface providing hydrophobicity to the polymer chain. Dicyclohexano-18-crown-6 (DCH18C6) was finally impregnated onto the polymer chain via a hydrophobic interaction between the octadecyl moiety of the polymer chain and the cyclohexyl moiety of DCH18C6. The fiber surface structure, characterized by DCH18C6 molecules loosely entangled with polymer chains, afforded realizes the rapid and selective adsorption of Sr ions with an adsorption rate approximately 100 times higher than that of a commercially available Sr-selective resin (Sr Resin).

Journal Articles

Removal of cesium ions from contaminated seawater in closed area using adsorptive fiber

Someya, Takaaki*; Asai, Shiho; Fujiwara, Kunio*; Sugo, Takanobu*; Umeno, Daisuke*; Saito, Kyoichi*

Nippon Kaisui Gakkai-Shi, 69(1), p.42 - 48, 2015/02

A large amount of seriously contaminated sea water with radioactive Cs has been reserved in semi-enclosed coastal sea area which is separated by silt fences and embankments. Insoluble cobalt ferrocyanide (Co-FC) microparticles-impregnated fiber was developed for removing Cs from the contaminated sea water. The resultant Co-FC-impregnated fiber was immersed in either nonradioactive or radioactive Cs solution. The adsorption isotherm well correlated with a Langmuir-type equation. In addition, mass-transfer capacity coefficients were determined by fitting the experimental data of the rate of Cs adsorption onto the Co-FC-impregnated fiber to theoretical adsorption curves based on the Cs concentration difference between the bulk and the interface in seawater as a driving force of the overall adsorption rate. Decontamination factors as functions of fiber weight and the contact time required for the removal of cesium ions from the contaminated seawater in a closed area were estimated.

Journal Articles

Removal of cesium using cobalt-ferrocyanide-impregnated polymer-chain-grafted fibers

Ishihara, Ryo*; Fujiwara, Kunio*; Harayama, Takato*; Okamura, Yusuke*; Uchiyama, Shoichiro*; Sugiyama, Mai*; Someya, Takaaki*; Amakai, Wataru*; Umino, Satoshi*; Ono, Tsubasa*; et al.

Journal of Nuclear Science and Technology, 48(10), p.1281 - 1284, 2011/10

AA2011-0190.pdf:0.45MB

 Times Cited Count:37 Percentile:4(Nuclear Science & Technology)

Journal Articles

Experimental study of the effect of radiation exposure to concrete

Fujiwara, Kazushige*; Ito, Masanobu*; Sasanuma, Miwa*; Tanaka, Hideo*; Hirotani, Kiyoshi*; Onizawa, Kunio; Suzuki, Masahide; Amezawa, Hiroo*

Transactions of 20th International Conference on Structural Mechanics in Reactor Technology (SMiRT-20) (CD-ROM), 8 Pages, 2009/08

Concerns over aged nuclear power stations are mounting in Japan today. However, there exists only a small number of experimental studies regarding the effect of radiation exposure to concrete. We have consequently conducted an irradiation test at JMTR on concrete specimens to confirm the effect of radiation exposure on the basic material properties of concrete. Irradiation temperature was kept lower than 65$$^{circ}$$C. The maximum fast neutron fluence reached 12$$times$$10$$^{18}$$ n/cm$$^{2}$$ (E$$>$$ 0.1 MeV), which is sufficiently exceeding total fast neutron fluence to be exposed to the concrete located at the exterior of a reactor pressure vessel in a typical BWR for 60-year operation. Compressive strength of the irradiated concrete specimens was roughly equivalent to that of concrete specimens cured for the same duration under the standard environment. By measuring chemically bound water content of irradiated specimens, no changes after irradiation were observed. It was confirmed that radiation exposure did not significantly affect the basic material properties of concrete within the range of radiation doses adopted in this study.

Oral presentation

Development of high-performance adsorptive fibers for decontamination of radioactive substances; Preparation of Sr-adsorptive fibers

Harayama, Takato*; Umino, Satoshi*; Asai, Shiho; Fujiwara, Kunio*; Saito, Kyoichi*; Sugo, Takanobu*

no journal, , 

no abstracts in English

Oral presentation

Development of high-performance adsorptive fibers for decontamination of radioactive substances; Production of Cs-adsorptive fiber and its adsorption performance

Okamura, Yusuke*; Fujiwara, Kunio*; Sugo, Takanobu*; Asai, Shiho; Saito, Kyoichi*

no journal, , 

no abstracts in English

Oral presentation

Preparation of crown ether derivative-impregnated Sr-adsorptive fibers for rapid analysis of Sr-90

Konda, Miki; Asai, Shiho; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Magara, Masaaki

no journal, , 

The concentration of $$^{90}$$Sr is normally determined with a beta counter, which involves time-consuming pretreatment procedures. To minimize such pretreatment procedures, an adsorbent achieving high-speed separation would be helpful. Adsorbents prepared by graft polymerization have an ideal surface structure, promoting efficient adsorption of analytes to functional groups of the polymer chain attached through the polymerization reaction. In this study, an extractant for Sr$$^{2+}$$, dicyclohexano-18-crown-6 (DC8C6) was impregnated onto alkylamino-group-introduced graft chains based on hydrophobic interaction. A nylon fiber was employed as a base polymer, which allows to form various shapes according to measurement modes. The amount of impregnated DC8C6 is comparable to those of commercially available Sr adsorbents. This indicates that the prepared fibers have an adequate adsorptivity for Sr ion from a practical perspective.

Oral presentation

Preparation of crown ether derivative-impregnated fiber based on the radiation-induced emulsion graft polymerization for rapid analysis of Sr-90

Horita, Takuma; Asai, Shiho; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Kitatsuji, Yoshihiro

no journal, , 

There has been an increasing demand for rapid analysis of $$^{90}$$Sr to ensure a prompt action against the contaminated water in the Fukushima Daiichi NPP. Precedent works demonstrated that Cs adsorption fibers prepared by utilizing graft polymerization technology achieved high-speed removal of $$^{137}$$Cs in the contaminated water. In this study, we have investigated the applicability of such proven technology to the preparation of a Sr adsorption fiber specialized for the selective extraction of Sr. In the prepared fiber, an extractant for Sr$$_{2+}$$,dicyclohexano-18-crown-6-ether (DCH18C6) was impregnated via hydrophobic interaction between DCH18C6 and the hydrophobic polymer chains attached onto the surface of the fiber. To increase the adsorption capacity, emulsion graft polymerization which promotes the polymer chains to grow longer was applied. The densely-packed DCH18C6 inside the interfacial phase formed by the polymer chains facilitates the efficient adsorption. The amounts of Sr adsorbed is comparable to those of conventional adsorbents, indicating that the prepared fiber has a feasible performance for Sr adsorption.

Oral presentation

Preparation of 18-crown-6-ether derivative-impregnated fiber based on the radiation-induced graft polymerization

Horita, Takuma; Asai, Shiho; Konda, Miki; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Kitatsuji, Yoshihiro

no journal, , 

High activity concentrations of $$^{90}$$Sr, which greatly exceed the regulatory limit (30 Bq/L), are detected in contaminated waters sampled in Fukushima Daiichi NPP. However, analytical method for $$^{90}$$Sr associated with time-consuming procedure causes delay in understanding the current status of $$^{90}$$Sr contamination. In this study, we have prepared a Sr adsorption fiber (Sr Fiber) based on radiation-induced graft polymerization technique to achieve a rapid adsorption of Sr ions. Dicyclohexano-18-crown-6 ether that has high affinity for Sr was impregnated in the hydrophobic interfacial phase provided by hydrophobic polymer chains attached on the fiber surface through graft polymerization. The time required to reach the Sr adsorption equilibrium for the Sr Fiber is approximately 180 times shorter than that for a commercially available Sr adsorbent (Sr Resin), showing that the Sr Fiber has a potential to efficiently reduce the analytical time of $$^{90}$$Sr.

Oral presentation

Direct beta-ray measurement of $$^{90}$$Sr adsorbed on fiber surface; Preparation of 18-crown 6-ether derivative-impregnated Sr adsorption fiber based on the radiation-induced graft polymerization

Horita, Takuma; Asai, Shiho; Konda, Miki; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Kitatsuji, Yoshihiro

no journal, , 

There has been an increasing importance of the development of rapid separation techniques for $$^{90}$$Sr analysis, responding to needs in Fukushima Daiichi NPP. However, conventional $$^{90}$$Sr analytical methods require two different separation steps for Sr and Y, respectively, resulting in a long processing time of about one month. In this study, we prepared a Sr adsorptive fiber (Sr fiber) that has a high density Sr adsorption phase on its surface, allowing to highly efficient $$beta$$-ray counting by minimizing the self-attenuation effects. The adsorption capacity of the prepared Sr fiber was about 14 g/mol, which is equivalent to that of a commercially available Sr adsorptive resin (Sr Resin). The selectivity of the Sr fiber was nearly the same as that of the Sr resin. Considering that the Sr fiber has a specific surface area 1000 times smaller than that of the Sr Resin, the Sr ions can be concentrated to 1000 times on its surface, capable of achieving highly-efficient $$beta$$-ray counting. From these result, we confirmed that Sr fiber has adsorption capacity and selectivity necessary for highly efficient $$beta$$-ray counting of $$^{90}$$Sr.

Oral presentation

Preparation of Sr adsorption fiber for beta-ray measurement

Horita, Takuma; Asai, Shiho; Hanzawa, Yukiko; Saito, Kyoichi*; Sugo, Takanobu*; Fujiwara, Kunio*; Kitatsuji, Yoshihiro

no journal, , 

There has been an increasing importance of the development of rapid $$^{90}$$Sr analysis technique, responding to needs in Fukushima Daiichi NPP. We have been trying to achieve a rapid analysis using a fibrous Sr adsorbent which has high selectivity for Sr$$^{2+}$$. The fiber we prepared that has a high-density Sr adsorption phase on its surface, and so it can adsorb Sr$$^{2+}$$ on the fiber surface. On the other hand, base material of a conventional Sr adsorptive resin for $$^{90}$$Sr analysis (Sr Resin) is bead-shaped resin, and $$^{90}$$Sr is adsorbed inside pores. The fiber allows highly efficient $$beta$$ counting by minimizing the self-attenuation effects. The adsorption capacity and selectivity of the fiber was nearly the same as those of the Sr Resin. From these results, we confirmed that the fiber has performance for efficient $$beta$$ counting of $$^{90}$$Sr.

Oral presentation

Development of in-situ analytical method of $$^{90}$$Sr in contaminated water using Sr adsorptive fiber

Konda, Miki; Horita, Takuma; Asai, Shiho; Matsueda, Makoto; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Kameo, Yutaka

no journal, , 

no abstracts in English

Oral presentation

Development of crown-ether-derivative impregnated fiber for in-situ analysis of $$^{90}$$Sr; Study of safe Sr adsorption with no nitric acid

Konda, Miki; Horita, Takuma; Asai, Shiho; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Ishimori, Kenichiro; Kameo, Yutaka

no journal, , 

no abstracts in English

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