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Journal Articles

Study of treatment scenarios for fuel debris removed from Fukushima Daiichi NPS

Washiya, Tadahiro; Yano, Kimihiko; Kaji, Naoya; Yamada, Seiya*; Kamiya, Masayoshi

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

On March 11, 2011, a severe nuclear accident occurred at Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi Nuclear Power Plant (hereinafter called as F1). After the accident, the Council for the Decommissioning was established, mainly by the government and TEPCO, and a road map for the F1 decommissioning was drawn up. In the road map, the fuel debris removal from the reactors is scheduled to launch around 2020. In this study, the characteristics and technological issues of each potential treatment scenario were extracted, and the scenarios were prioritized in advance of formal evaluations in the future. The preliminary evaluation results show that long term storage and direct disposal have more positive aspects in terms of economic efficiency and radioactive waste generation. On the other hand, stabilizing processing, aqueous processing, and pyrochemical processing have been estimated to have more disadvantages in such aspects.

Journal Articles

Dissolution behavior of (U,Zr)O$$_{2}$$-based simulated fuel debris in nitric acid

Ikeuchi, Hirotomo; Ishihara, Miho; Yano, Kimihiko; Kaji, Naoya; Nakajima, Yasuo; Washiya, Tadahiro

Journal of Nuclear Science and Technology, 51(7-8), p.996 - 1005, 2014/07

 Times Cited Count:10 Percentile:59.32(Nuclear Science & Technology)

Journal Articles

Direction on characterization of fuel debris for defueling process in Fukushima Daiichi Nuclear Power Station

Yano, Kimihiko; Kitagaki, Toru; Ikeuchi, Hirotomo; Wakui, Ryohei; Higuchi, Hidetoshi; Kaji, Naoya; Koizumi, Kenji; Washiya, Tadahiro

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1554 - 1559, 2013/09

Journal Articles

Suggestion of typical phases of in-vessel fuel-debris by thermodynamic calculation for decommissioning technology of Fukushima-Daiichi Nuclear Power Station

Ikeuchi, Hirotomo; Kondo, Yoshikazu*; Noguchi, Yoshihiro*; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1349 - 1356, 2013/09

Journal Articles

Nitric acid concentration dependence of dicesium plutonium(IV) nitrate formation during solution growth of uranyl nitrate hexahydrate

Nakahara, Masaumi; Kaji, Naoya; Yano, Kimihiko; Shibata, Atsuhiro; Takeuchi, Masayuki; Okano, Masanori; Kuno, Takehiko

Journal of Chemical Engineering of Japan, 46(1), p.56 - 62, 2013/01

 Times Cited Count:1 Percentile:6.16(Engineering, Chemical)

The influence of HNO$$_{3}$$ concentration in the solution on the formation of Cs$$_{2}$$Pu(NO$$_{3}$$)$$_{6}$$ was evaluated in the U crystallization process. The solubility of Cs$$_{2}$$Pu(NO$$_{3}$$)$$_{6}$$ in a uranyl nitrate solution was found to decrease with increasing HNO$$_{3}$$ concentration in the solution. In the U crystallization experiments with the dissolver solution of irradiated fast reactor fuel, Cs$$_{2}$$Pu(NO$$_{3}$$)$$_{6}$$ formed with 6.5 mol/dm$$^{3}$$ HNO$$_{3}$$ concentration in the mother liquor, and the decontamination factor of Cs for the uranyl nitrate hexahydrate crystals was low. Meanwhile, Cs$$_{2}$$Pu(NO$$_{3}$$)$$_{6}$$ did not precipitate with uranyl nitrate hexahydrate crystals under the condition of 4.0 mol/dm$$^{3}$$ HNO$$_{3}$$ concentration in the mother liquor, and Cs could be separated from the uranyl nitrate hexahydrate crystals.

JAEA Reports

Elution properties of cesium contained within irradiated fast neutron reactor fuel in water and diluted nitric acid solution

Nakahara, Masaumi; Kaji, Naoya; Nomura, Kazunori

JAEA-Research 2012-009, 15 Pages, 2012/06

JAEA-Research-2012-009.pdf:6.37MB

In terms of preventing the formation of Pu and Cs compound, Cs in the feed solution should decrease in the U crystallization process. In order to separate Cs contained within irradiated nuclear fuel, the immersion experiments were carried out with the pure water and diluted HNO$$_{3}$$ solution. The elusion ratio of Cs within the powdered fuel in the pure water and 0.1 mol/dm$$^{3}$$ HNO$$_{3}$$ solution after 67 h was 33.8 and 38.3%, respectively. The experimental results suggest a possible beneficial effect of Cs elusion by immersion of the powdered fuel in the pure water and diluted HNO$$_{3}$$ solution before the fuel dissolution process.

Journal Articles

Salt-free technique for solvent washing process in NEXT process

Sano, Yuichi; Kaji, Naoya; Shibata, Atsuhiro; Takeuchi, Masayuki; Washiya, Tadahiro

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 7 Pages, 2011/12

Journal Articles

A Consideration on proliferation resistance of a FBR fuel cycle system

Inoue, Naoko; Kaji, Naoya; Suda, Kazunori; Kawakubo, Yoko; Suzuki, Mitsutoshi; Koyama, Tomozo; Kuno, Yusuke; Senzaki, Masao

Proceedings of INMM 51st Annual Meeting (CD-ROM), 10 Pages, 2010/07

Journal Articles

Current status on research and development of uranium crystallization system in advanced aqueous reprocessing of FaCT project

Shibata, Atsuhiro; Kaji, Naoya; Nakahara, Masaumi; Yano, Kimihiko; Tayama, Toshimitsu; Nakamura, Kazuhito; Washiya, Tadahiro; Myochin, Munetaka; Chikazawa, Takahiro*; Kikuchi, Toshiaki*

Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.151 - 157, 2009/09

As a part of FaCT project, Japan Atomic Energy Agency has been developing a U crystallization process for advanced aqueous reprocessing technology in collaboration with Mitsubishi Materials Corporation. We have carried out experimental studies and obtained fundamental data. Continuous operation tests were also carried out by an engineering-scale crystallizer to confirm productivity of the equipment and to investigate non-steady state conditions. The requirements for the U crystallization process in the FaCT project could be achieved except DF of Cs. More detail investigation is under way to settle the process condition without Pu-Cs double salt formation.

Journal Articles

Dissolution of powdered spent fuel and U crystallization from actual dissolver solution for "NEXT" process development

Nomura, Kazunori; Hinai, Hiroshi; Nakahara, Masaumi; Kaji, Naoya; Kamiya, Masayoshi; Oyama, Koichi; Sano, Yuichi; Washiya, Tadahiro; Komaki, Jun

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 5 Pages, 2008/05

Oral presentation

Development of actinides co-extraction system with direct extraction process using supercritical fluid, 16; Integrated evaluation

Kamiya, Masayoshi; Kaji, Naoya; Koyama, Tomozo; Aoki, Kazuo*; Yamada, Seiya*

no journal, , 

Main process of actinides co-extraction system with direct extraction process using supercritical fluid was designed. The improvement effect of the cost performance was small because multiple lines were needed about main process. But we got the evaluation result that it is possible to reduce substantially about waste liquid treatment. Based on the result, the improvement which uses supercritical fluid for partitioning was gathered.

Oral presentation

Oral presentation

Selection of fuel-debris properties required for defueling work at post severe accident

Ikeuchi, Hirotomo; Kitagaki, Toru; Wakui, Ryohei; Higuchi, Hidetoshi; Koizumi, Kenji; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro

no journal, , 

Oral presentation

Assumption and comparison of fuel debris properties between TMI-2 and 1F for future defueling work

Kitagaki, Toru; Ikeuchi, Hirotomo; Yano, Kimihiko; Hoshino, Takanori; Kaji, Naoya; Washiya, Tadahiro

no journal, , 

Oral presentation

Estimation of chemical forms of in-vessel fuel-debris by combination of melt-progression analysis and thermodynamic equilibration

Ikeuchi, Hirotomo; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro; Kondo, Yoshikazu*; Noguchi, Yoshihiro*

no journal, , 

no abstracts in English

Oral presentation

Characterization of fuel debris (27'A), 1; Outline of the project

Washiya, Tadahiro; Ogino, Hideki; Kaji, Naoya; Miyamoto, Yasuaki; Kawano, Shohei*

no journal, , 

JAEA, as a member of IRID, had started experimental and analytical studies on characterization of fuel debris. In this paper, research summary on the characterization of fuel debris and current research results will be described.

Oral presentation

Study on application of aqueous treatment for fuel debris in post severe accident, 1; Fundamental test on dissolution of uranium and zirconium oxide solid solution by nitric acid

Hoshino, Takanori; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro; Fukasawa, Tetsuo*; Ohara, Hiroshi*

no journal, , 

no abstracts in English

Oral presentation

Feasibility study on application of aqueous treatment for fuel debris in post severe accident, 2; Suggestion on solubilization of fuel debris for nitric acid by solution treatment with UO$$_{2}$$

Yano, Kimihiko; Hoshino, Takanori; Kaji, Naoya; Washiya, Tadahiro; Fukasawa, Tetsuo*; Ohara, Hiroshi*

no journal, , 

A part of study on the management of fuel debris in unit 1-3 at Fukushima Dai-ichi Nuclear Power Station, it is suggested that solubilization of fuel debris for nitric acid by solution treatment with UO$$_{2}$$. It was experimentally confirmed that this process made insoluble (U,Zr)O$$_{2}$$, one of the major components, be dissoluble.

Oral presentation

Thermodynamic calculation on chemical forms of in-vessel debris of Fukushima-Daiichi NPP

Ikeuchi, Hirotomo; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro; Kondo, Yoshikazu*; Noguchi, Yoshihiro*

no journal, , 

no abstracts in English

38 (Records 1-20 displayed on this page)