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Oral presentation

Challenges for Fukushima environmental restoration; JAEA's perspective

Miyahara, Kaname; Iijima, Kazuki

no journal, , 

This presentation provides a concise overview of knowledge and experience gained from the activities for environmental remediation after the Fukushima Dai-ichi accident to establish the technical basis for strategic, off-site response to nuclear incidents. It is produced by JAEA, reflecting JAEA's key role in the research associated with both remediation of contaminated areas and the natural processes influencing contamination migration in non-remediated areas. This presentation also provides a perspective on the future actions to facilitate return of residents to the most contaminated zones from the standpoint of environmental chemistry and radiochemistry with special emphasis on associated waste management.

Oral presentation

Solubility of Niobium in aqueous solution containing high pH conditions

Iwata, Hajime; Kitamura, Akira

no journal, , 

The solubility of Nb was measured using oversaturation and undersaturation method. Compared with the values evaluated using JAEA-TDB, in the OS method a similar solubility was observed, and the measured values in the US method were around three orders magnitude below the evaluated values. It suggests that the solubility limiting solid differ between OS and US method.

Oral presentation

Development of 2-[$$^{211}$$At]astato-$$alpha$$-methyl-L-phenylalanine (2-AAMP) as a novel radiopharmaceutical for internal radiotherapy

Ohshima, Yasuhiro; Suzuki, Hiroyuki*; Hanaoka, Hirofumi*; Watanabe, Shigeki; Watanabe, Satoshi; Watanabe, Naoyuki*; Tsushima, Yoshito*; Endo, Keigo*; Arano, Yasushi*; Ishioka, Noriko

no journal, , 

Oral presentation

Adsorption-desorption behavior of trace-level alkali metals on oxides and micaceous oxides

Baba, Yuji; Shimoyama, Iwao; Hirao, Norie; Izumi, Toshinori

no journal, , 

In order to clarify the chemical states of radioactive cesium in clay minerals, the X-ray photoelectron spectra (XPS) have been measured for cesium and the other alkali metals on oxides and micaceous oxides. Since the number of atoms in radioactive Cs-137 is extremely small, we focused on the adsorption of trace amount of cesium. For this purpose, we applied total reflection XPS (TR-XPS) using synchrotron radiation. For micaceous oxide, the TR-XPS spectra show that the cesium is more positively charged compared with that for thicker layer. It was shown that trace-level cesium in micaceous oxides is ionically bonded at the interlayer due to the negative charge of the micaceous oxide. We consider that the observed unique adsorption-desorption behavior is specific to only trace-level cesium.

Oral presentation

Molecular laser isotope separation without tunable lasers; Isotope-selective ionization of N$$_{2}$$ isotopologues using femtosecond laser-induced molecular alignment

Akagi, Hiroshi; Kasajima, Tatsuya*; Kumada, Takayuki; Itakura, Ryuji; Yokoyama, Atsushi; Hasegawa, Hirokazu*; Oshima, Yasuhiro*

no journal, , 

We propose a laser isotope separation method without tunable lasers, and demonstrate isotope selective ionization of nitrogen isotopologues. This method is based on molecular alignment and angular dependent ionization. A non-resonant femtosecond (fs) laser pulse with a linear polarization creates rotational wave packets in the isotopologues. These wave packets periodically exhibit aligned and antialigned distributions at specific time delays. At a specific time delay when one isotopologue is aligned and the other one is anti-aligned, another non-resonant linearly-polarized fs laser pulse (ionization pulse) ionizes the aligned isotopologue preferentially via the non-resonant multiphoton ionization, because of angular dependence of the N$$_{2}$$ ionization probability. The ion yield ratio R [= I($$^{15}$$N$$_{2}$$) / I($$^{14}$$N$$_{2}$$)] depends on the time delay, ranging from 0.68 to 1.41.

Oral presentation

Fundamental study of conditioning of wastes generated from several contaminated water treatment devices in Fukushima Daiichi Nuclear Power Station

Meguro, Yoshihiro; Sato, Junya; Kato, Jun; Nakagawa, Akinori; Koma, Yoshikazu; Ashida, Takashi

no journal, , 

A large quantity of contaminated water is accumulated in nuclear reactor buildings in Fukushima Daiichi Nuclear Power Station. Because various radionuclides are dissolved in the accumulated water, several decontamination devices based on deposition and adsorption are used for the decontamination. Therefore, several sludge and used adsorption materials are generated. These most are different from wastes caused by the operation of commercial nuclear power stations so far in properties, and these have not been disposed of commercially. As then feasibility of conventional solidification techniques to the wastes should be investigated prior to selection of solidification technique of the wastes. In this study as a first step of feasibility study, three types of sludge and three absorbents were solidified using cement materials and solidification behavior and properties of solidified material were investigated, and then feasibility of cementation to these wastes was evaluated.

Oral presentation

Synthesis of a nitrogen-containing carbon material with oxygen reduction activity from polymer precursors

Idesaki, Akira; Sugimoto, Masaki; Shimada, Akihiko; Yamamoto, Shunya; Taguchi, Mitsumasa; Yamaki, Tetsuya

no journal, , 

Recently, development of platinum-substitute catalysts has been studied extensively; it has been found that a nitrogen-containing carbon material shows oxygen reduction activity almost same as platinum metal. We have been studying about synthesis process of a nitrogen-containing carbon material by pyrolysis of polymer precursors which are easy to be shaped as fiber, film, and so on. In this work, some materials were selected as polymer precursors and their organic-inorganic conversion process were investigated. It was found that polyimide and phenol resin show high carbon yield of 50-60% and graphite structure is formed above 800$$^{circ}$$C.

Oral presentation

Medical radioisotope production with accelerator neutrons by deuterons

Tsukada, Kazuaki; Sato, Nozomi*; Watanabe, Satoshi; Ishioka, Noriko; Hatsukawa, Yuichi; Hashimoto, Kazuyuki; Kin, Tadahiro*; Takeda, Shinsaku*; Kawabata, Masako; Saeki, Hideya; et al.

no journal, , 

A new system has been proposed for the generation of radioisotopes with accelerator neutrons by deuterons, especially the production of Mo-99, Y-90, Cu-67, and Cu-64. Enriched Mo-100, Zr-90, Zn-68 and Zn-64 oxide samples were irradiated with neutrons, which were obtained by the $$^{nat}$$C(d,n) and Be(d,n) using 40 MeV deuterons provided from the TIARA cyclotron. Mo-99, Y-90, Cu-67, and Cu-64 were successfully produced via the (n, x) reactions, and we clearly observed the $$gamma$$-rays. Particularly, yields of impurity radionuclides were much smaller than that of Mo-99 and Cu-67, and therefore radioactive waste produced during chemical processing would be reduced compared with other proposed reaction systems. The present results demonstrate that the radioisotopes, Mo-99, Y-90, Cu-67, and Cu-64, can be produced by using fast neutrons, and strongly suggest that the reaction system is one of the most promising routes to produce high quality medical radioisotope.

Oral presentation

Boron removal by glucamine chelate adsorbent grafted on polyethylene fabric

Seko, Noriaki; Amada, Haruyo; Hoshina, Hiroyuki; Ikegawa, Atsushi*; Hatanaka, Hiroshi*

no journal, , 

Oral presentation

Synthesis of fibrous adsorbent for dysprosium by radiation-induced graft polymerization

Hoshina, Hiroyuki; Seko, Noriaki; Ikegawa, Atsushi*; Hatanaka, Hiroshi*

no journal, , 

Oral presentation

Consideration of water radiolysis in void volumes of porous zeolite bed loaded in adsorption vessels for decontamination of radioactive water

Nagaishi, Ryuji; Inoue, Masao; Matsumura, Taichi; Yamagishi, Isao; Hino, Ryutaro; Ogawa, Toru

no journal, , 

Hydrogen gas generation in radiolysis of pure water or seawater coexisting with zeolite adsorbents has been investigated by using Co-60 $$gamma$$-ray for hydrogen safety in decontamination of radioactive water after Fukushima Daiichi NPS accident. In this work, two types of void volumes present in the zeolite bed were paid attention microscopically, and the difference in water radiolysis between the volumes was considered. The oxygen generated by decomposition of hydrogen peroxide, as the counterpart of hydrogen molecule, contacting with the zeolites were also discussed.

Oral presentation

Utilization of advanced radiation facilities under cooperation program with academics

Hirota, Koichi; Sawahata, Hiroyuki*

no journal, , 

Takasaki Advanced Radiation Research Institute has three irradiation facilities of ion-beam, $$gamma$$-ray, and electron-beam aimed at developing cutting-edge technologies for advanced materials, environmental conservation, biotechnology, and medical application. These facilities are available for basic and applied researches by academics, national and local government institutes, and private companies under the cooperation program. For example, the cyclotron is used for researches on radiation-degradation phenomena of semiconductors for space use, controlled polymerization of nanowire, breed improvement etc. The $$gamma$$-ray facilities contribute to diverse research themes and recent noteworthy work is development of radiation-resistant materials for the decommissioning of damaged Fukushima Daiichi Nuclear Power Plant. Users under this cooperation program have advantages of preferential utilization of machine time and utilization fee subsidization. This presentation focuses on the detail of this program with the examples of actual research results.

Oral presentation

SANS and EXAFS study of hierarchical structure assembled by coordination species in biphasic solvent extraction

Motokawa, Ryuhei; Kobayashi, Toru; Endo, Hitoshi*; Suzuki, Shinichi; Yaita, Tsuyoshi; Shiwaku, Hideaki

no journal, , 

Oral presentation

Electrochemistry of the heaviest elements at JAEA

Toyoshima, Atsushi

no journal, , 

Electrochemical studies of the heaviest elements carried out at JAEA will be presented. We have so far studied the oxidation of nobelium (No) and the reduction of mendelevium (Md) using a flow electrolytic column (FEC) apparatus. In these experiments, thin glassy carbon fibers modified with ion-exchange resin were employed as a working electrode as well as a cation-exchanger to identify oxidation states of single atoms. Chromatograms of $$^{255}$$No and $$^{255}$$Md produced in the $$^{248}$$Cm($$^{12}$$C, 5n) and $$^{248}$$Cm($$^{11}$$B, 4n) reactions, respectively, at the JAEA tandem accelerator were varied with increasing the applied potential on the working electrode. This proved that redox reactions of No and Md occur in the studied potential ranges. Recently, we newly started exploring electrochemical reduction of Sg using a new chemistry assembly consisting of a membrane degasser, a FEC, the continuous liquid-liquid extraction apparatus. In the congress, results on these electrochemistry experiments will be presented.

Oral presentation

Production of $$^{95m}$$Tc for Compton camera imaging

Hatsukawa, Yuichi; Tsukada, Kazuaki; Hashimoto, Kazuyuki; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Nagai, Yasuki; Tanimori, Toru*; Sonoda, Shinya*; Kabuki, Shigeto*; et al.

no journal, , 

In recent years, the Compton camera which is originally developed for the astrophysical studies was applied for medical diagnostic usage. For the Compton camera imaging require technetium isotopes emitting higher energy $$gamma$$-rays. Two Tc isotopes, $$^{95m}$$Tc (T$$_{1/2}$$ = 60 d; E$$gamma$$ = 204, 582 and 835 keV) and $$^{96}$$Tc(T$$_{1/2}$$ = 4.28 d, E$$gamma$$ = 778 and 812 keV) are candidates for Compton camera imaging. Compton camera imaging can realize high position resolution without collimator. Because of no collimator using, the Compton camera makes higher $$gamma$$-ray detection efficiency. Compared with SPECT with $$^{99m}$$Tc, the Compton camera imaging technique can be expected that radiation exposure deduce to 1/5-1/10. In this study, technetium-95m was produced by the $$^{95}$$Mo(p,n)$$^{95m}$$Tc reaction.

Oral presentation

Improvement in production yield of $$^{85}$$Sr@C$$_{60}$$ using nuclear recoil

Miyashita, Yuka*; Akiyama, Kazuhiko*; Hatsukawa, Yuichi; Kubuki, Shiro*

no journal, , 

To obtain an endohedral metallofullerenes with high specific radioactivity using nuclear recoil phenomena, many experiments have been performed so far. However, production yield of metallofullerene by nuclear recoil using high LET radiation was found to be very small because radiation damages to targeted fullerene molecule were not negligible. In order to increase the yield of radioactive metallofullerenes, it is very promising to employ the recoil of nuclear reaction by fast neutron from the viewpoint of reducing the radiation damage. In this session, we will report the synthesis of $$^{85}$$Sr@C$$_{60}$$ using nuclear recoil of $$^{86}$$Sr(n,2n)$$^{85}$$Sr reaction by 14 MeV fast neutron. Mixture of C$$_{60}$$ with strontium salts such as Sr(NO$$_{3}$$)$$_{2}$$ and SrC$$_{2}$$O$$_{4}$$ were employed for the target materials. These samples were irradiated by fast neutron in Fusion Neutronics Source at Japan Atomic Energy Agency. After the irradiation, CS$$_{2}$$, aniline, and HCl$$_{aq}$$ were passed through the irradiated samples on the filter to dissolve C$$_{60}$$, Sr@C$$_{60}$$, and strontium salts, respectively. The $$gamma$$-ray from these solutions were measured by Ge detector. As a result, about 0.75 % of radioactivity was observed in the aniline solution from SrC$$_{2}$$O$$_{4}$$ sample. This result strongly suggests that Sr@C$$_{60}$$ was efficiently produced by fast neutron irradiation of SrC$$_{2}$$O$$_{4}$$/C$$_{60}$$ target.

Oral presentation

Isotope fractionation in AgI super-ionic conductor by centrifugation

Ono, Masao; Okayasu, Satoru; Iguchi, Yusuke*; Esaka, Fumitaka; Ishitsuka, Etsuo; Osawa, Takahito; Ogata, Yudai; Mashimo, Tsutomu*

no journal, , 

Oral presentation

Extraction behavior of Mo and W from H$$_{2}$$SO$$_{4}$$ with Aliquat336 as homologues of seaborgium (Sg)

Mitsukai, Akina; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Kaneya, Yusuke; Takeda, Shinsaku*; Nagame, Yuichiro; Komori, Yukiko*; Murakami, Masafumi*; et al.

no journal, , 

We have started studying sulphate-complex formation of a transactinide element, seaborgium (Sg). In this study, we report on the extraction behavior of carrier-free radioisotopes $$^{93m}$$Mo and $$^{181}$$W which are lighter homologs of Sg, from aqueous H$$_{2}$$SO$$_{4}$$ solution with amine extractant, Aliquat336, dissolved in toluene by a batch method. These radioisotopes were produced in the $$^{nat}$$Zr($$alpha$$,${it 2}$)$$^{93m}$$Mo and $$^{181}$$Ta(${it d}$,x${it n}$)$$^{181}$$W reactions at the RIKEN K70 AVF cyclotron. Results of the extraction experiments showed that the distribution ratios of Mo and W increase sharply above ~3.0 M H$$_{2}$$SO$$_{4}$$. Based on the slope analysis, it was indicated that anionic sulphate-complex of [MO$$_{2}$$(SO$$_{4}$$)$$_{2}$$]$$^{2-}$$ (M = Mo, W) are formed in $$>$$ 5 M H$$_{2}$$SO$$_{4}$$. These results suggest that the present system is applicable to the extraction of Sg.

Oral presentation

Adsorption properties of cesium to micaceous clay minerals; Molecular modeling using density functional theory calculations

Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko; Sassi, M.*; Rosso, K.*

no journal, , 

no abstracts in English

Oral presentation

Structure of water and polymer network in poly(vinyl alcohol) hydrogels with repeated freezing-thawing cycles

Sekine, Yurina; Ishikawa, Nozomi*; Fukazawa, Tomoko*

no journal, , 

no abstracts in English

32 (Records 1-20 displayed on this page)