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Journal Articles

Mechanism of flashing phenomena induced by microwave heating

Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Yamada, Yoshikazu; Kato, Yoshiyuki; Ishii, Katsunori

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 8 Pages, 2018/07

Mixed uranium oxide and plutonium oxide powder is produced from uranyl nitrate and plutonium nitrate mixed solution by the microwave heating denitration method in the spent fuel reprocessing process. Since the microwave heating method is accompanied by a boiling phenomenon, it is necessary to fully grasp the operating conditions in order to avoid flashing and spilling in the mass production of denitrification technology for the future. In this research, it was confirmed that a potassium chloride aqueous solution as a simulant of uranyl nitrate aqueous solution with high dielectric loss cause loss of microwave at the solution surface as the dielectric loss increased with the increase of KCl concentration by experimental and electromagnetic field analysis, and revealed that the change in the heating condition affects the generation of flushing.

Journal Articles

Development of active neutron NDA techniques for nuclear non-proliferation and nuclear security, 1; Performance evaluation of Next-Generation DDA technique

Ozu, Akira; Maeda, Makoto; Komeda, Masao; Furutaka, Kazuyoshi; Toh, Yosuke

Nihon Kaku Busshitsu Kanri Gakkai Dai-38-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2018/04

no abstracts in English

Journal Articles

Analysis of the trends on minimization of proliferation risk

Suda, Kazunori; Shimizu, Ryo; Tazaki, Makiko; Tamai, Hiroshi; Kitade, Yuta

Nihon Kaku Busshitsu Kanri Gakkai Dai-38-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2018/04

Since India's nuclear explosion in 1974, there has been continued discussion on nuclear non-proliferation. At first, to prevent proliferation of nuclear weapons, the International Nuclear Fuel Cycle Evaluation (INFCE) was established to discuss reprocessing, plutonium handling, and so on. After that, to respond to the threat of proliferation posed by DPRK, the international community desired to further enhance nuclear non-proliferation by strengthening the IAEA safeguards system. In recent years, some researchers at universities and national laboratories are studying proliferation resistance from the standpoint of nuclear materials that may be inherently self-protecting. This paper discusses minimization of proliferation risk and future prospects based on alternative measures for reprocessing, plutonium handling, and recycling described in INFCE-WG4.

JAEA Reports

Investigative report on the PVC bag burst in the contamination incident at Plutonium Fuel Research Facility; Radiolysis of organic materials and raising of internal pressure

Cause Investigation Team for the PFRF Contamination Incident

JAEA-Review 2017-038, 83 Pages, 2018/03

JAEA-Review-2017-038.pdf:11.37MB

The contaminated accident occurred at Plutonium Fuel Research Facility on June, 2017. The PVC bag packaging in a fuel storage container burst when a worker opened the lid, and a part of contents (uranium and plutonium) was spattered over the room. In order to clarify the cause of the burst, the Cause Unfolding Team collected information concerning characteristics of the contents from any past records and interview. And then we observed and analyzed the contents in a glove box. We also performed experiments on radiolysis of organic materials, degradation of PVC bag by $$gamma$$ radiation, and PVC bag burst. Based on fault tree analysis, finally we concluded that the main gas generation source was alpha radiolysis of the epoxy resin mixed with the fuel powder. We hope that the calculation procedures for the gas generation and the inner pressure transition described in this report can be useful reference for the management of fuel storage in other facilities.

Journal Articles

Characterization study of four candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station

Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Maeda, Makoto; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.

Energy Procedia, 131, p.258 - 263, 2017/12

 Percentile:100

Journal Articles

Present state of partitioning and transmutation of long-lived nuclides, 4; Transmutation system using accelerator driven system and technology maturity of partitioning and transmutation

Tsujimoto, Kazufumi; Arai, Yasuo; Minato, Kazuo

Nippon Genshiryoku Gakkai-Shi, 59(11), p.644 - 648, 2017/11

no abstracts in English

Journal Articles

Flushing phenomena and flow structure by microwave heating

Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Chonan, Fuminori*; Yuasa, Tomohisa*; Yamaki, Tatsunori*; Segawa, Tomoomi; Yamada, Yoshikazu

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 8 Pages, 2017/07

From the observation results, in the process of flushing, the behaviors leading to flushing were classified divided into three types. First type is that first generation bubble from heating leads to flushing. Second type is that nucleate boiling continues during heating and stop, finally single bubble generates and leads to flushing. Third type is defined that gradual evaporation occurs without bubbles. It was revealed that the total quantities of heat released by flushing are approximately equal when assuming the flushing mechanism, it can be triggered that a large amount of micro bubbles are instantaneously generated and grew.

Journal Articles

Prospective features for integration of nuclear forensics capability in national framework

Tamai, Hiroshi; Okubo, Ayako; Kimura, Yoshiki; Shinohara, Nobuo; Tazaki, Makiko; Shimizu, Ryo; Suda, Kazunori; Tomikawa, Hirofumi

Proceedings of INMM 58th Annual Meeting (Internet), 6 Pages, 2017/07

Nuclear forensics is a technical measure to analyse and collate samples of illegally used nuclear materials, etc., to clarify their origins, routes, etc. and contribute to criminal identifications. Close collaboration with police and judicial organizations is essential. The national response framework is being built up with international cooperation. Discussions on promoting technical capability and regional cooperation are presented.

Journal Articles

Estimation of corrosion mechanisms from the data obtained by the reproduced experiments considering the actual environments; Maritime structures and nuclear facilities

Yamamoto, Masahiro

Zairyo To Kankyo, 66(1), p.3 - 12, 2017/01

The laboratory simulation tests which could be reproduced the corrosion reactions propagating in the actual environments were utilized to analyze the mechanism of corrosion phenomena. In this report, some results are introduced in the cases of maritime structures and nuclear facilities. Experimental apparatus was originally designed to obtain the data in high radioactive condition simulating actual plants. One is a result showing the effect of Np ion to the corrosion of stainless steel in nuclear fuel reprocessing plant. Corrosion mechanism was revealed that Np$$^{6+}$$ ion is reduced to Np$$^{5+}$$ ion by a corrosion reaction of stainless steel and then re-oxidized to Np$$^{6+}$$ ion in the bulk solution. And repetition of this cycle accelerated corrosion of stainless steel by a little amounts of Np addition in nitric acid solution. Another result is introduced that an effect of H$$_{2}$$O$$_{2}$$ created by radiolysis of cooling water at high radioactive environment in light water reactor.

Journal Articles

Symposium on "Science of nuclear fuel cycle and backend; Research and education" with a memory of Professor Joonhong Ahn, the University of California, Berkeley

Nakayama, Shinichi; Okumura, Masahiko*; Nagasaki, Shinya*; Enokida, Yoichi*; Umeki, Hiroyuki*; Takase, Hiroyasu*; Kawasaki, Daisuke*; Hasegawa, Shuichi*; Furuta, Kazuo*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(2), p.131 - 148, 2016/12

A symposium "Science of nuclear fuel cycle and backend - Research and education -" was held at the Univer-sity of Tokyo in June 25, 2016. This aimed at developing the research on nuclear fuel cycle and backend. The time and the number of participants of the symposium were limited, but the active discussion was conducted, and the common perception for the future was shared among the experienced participants in those fields. This paper provides the discussions made in the symposium, and also, as a memory to Professor Ahn, the University of California, Berkeley, his prominent achievements in academic research and education.

Journal Articles

Influence of the heating method on the particle characteristics of copper oxide powders synthesized from copper nitrate aqueous solutions

Segawa, Tomoomi; Fukasawa, Tomonori*; Huang, A.-N.*; Yamada, Yoshikazu; Suzuki, Masahiro; Fukui, Kunihiro*

Chemical Engineering Science, 153, p.108 - 116, 2016/10

 Times Cited Count:1 Percentile:88.21(Engineering, Chemical)

The influence of the heating method and rate on the morphology of CuO powders synthesized from Cu(NO$$_{3}$$)$$_{2}$$$$cdot$$3H$$_{2}$$O aqueous solutions by denitration was investigated. The median diameter of the obtained powder was found to decrease as the heating rate increased, independent of the heating method. The microwave heating method remarkably reduced the particle size and enhanced the irregularity and disorder of the shape and surface of the particles, which were found to be more widely distributed. In contrast, the microwave hybrid heating method yielded the most spherical particles with the smoothest surface. It was also found that this heating method sharpened the particle size distribution and had higher energy efficiency than the MW method. Numerical simulations also indicated a difference in the energy efficiency between these two methods. The simulations also revealed that the hybrid method could heat the whole reactor more uniformly with a lower microwave output.

Journal Articles

Characterization study of four candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station (Interim report)

Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Maeda, Makoto; Nauchi, Yasushi*; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.

Proceedings of INMM 57th Annual Meeting (Internet), 10 Pages, 2016/07

Journal Articles

Nickel oxide powder synthesis from aqueous solution of nickel nitrate hexahydrate by a microwave denitration method

Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Arimitsu, Naoki*; Yoshida, Hideto*; Fukui, Kunihiro*

Advanced Powder Technology, 26(3), p.983 - 990, 2015/05

 Times Cited Count:3 Percentile:76.15(Engineering, Chemical)

Denitration of the aqueous solution of nickel nitrate hexahydrate (Ni(NO$$_{3}$$)$$_{2}$$$$cdot$$6H$$_{2}$$O) by a microwave heating method was investigated. Since Ni(NO$$_{3}$$)$$_{2}$$$$cdot$$6H$$_{2}$$O aqueous solution cannot be heated to over 300 $$^{circ}$$C by microwave irradiation owing to the low microwave absorptivity of its intermediate, NiO could not previously be obtained by microwave heating. We propose a novel NiO synthesis method that uses microwave heating without the risk of chemical contamination. A NiO powder reagent was added to the solution as a microwave acceptor. The denitration efficiency to NiO could be improved by an adiabator around the reactor to increase the temperature homogeneity in the reactor. Numerical simulations also reveal that the use of the adiabator results in remarkable changes in the electromagnetic field distribution in the reactor, temperature inhomogeneity decreases.

Journal Articles

Sludge behavior in centrifugal contactor operation for nuclear fuel reprocessing

Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Okamura, Nobuo; Koizumi, Kenji

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

Journal Articles

Application of Laser-Induced Breakdown Spectroscopy (LIBS) analysis to molten alloy production process

Ozu, Akira; Tachi, Yoshiaki; Arita, Yuji*

Reza Kenkyu, 42(12), p.913 - 917, 2014/12

Laser-induced breakdown spectroscopy (LIBS) analysis has been applied to the molten alloy production process, in which simulated metals (Zr, Cu, Sm, Ce) are used instead of nuclear metallic fuels contained minor actinide (MA), with the aim of in-situ monitoring the elementary composition of the surface of the molten alloy in a chamber and vapor particles generated from the surface of the molten alloy. The variation in the ratio of elementary composition of the surface of the molten alloy in the crucible was successfully observed depending on temperature of the crucible. The elementary composition of the vapor particles appeared in the molten alloy chamber was also measured. The practical experimental results show that LIBS technique is very useful for investigating the elementary composition in the process and understanding the behavior of molten alloy in the crucible.

Journal Articles

Study on the effect of phosphorous concentration on intergranular corrosion of stainless steel in boiling nitric acid solution

Ueno, Fumiyoshi; Komatsu, Atsushi; Igarashi, Takahiro; Yamamoto, Masahiro

Proceedings of European Corrosion Congress 2014 (EUROCORR 2014) (USB Flash Drive), 10 Pages, 2014/09

In this paper, the effect of phosphorous concentration in grain boundary (GB) on intergranular corrosion (IC) progress was studied to understand GB corrosion behavior of stainless steels in boiling nitric acid solution. Phosphorus (P) added extra high purity type 310 stainless alloy was corroded in boiling nitric acid solution, and P in GB was detected by three-dimensional atom probe. IC progress considering with P profile in GB was studied by numerical simulation using cellular automaton method. As the results, we concluded that P concentration change around 1.4at% in GB of the alloy caused IC rate change in boiling nitric acid solution. The developed numerical method could simulate GB corrosion change with P distribution in GB.

Journal Articles

Mechanism of synthesis of metallic oxide powder from aqueous metallic nitrate solution by microwave denitration method

Fukui, Kunihiro*; Igawa, Yusuke*; Arimitsu, Naoki*; Suzuki, Masahiro; Segawa, Tomoomi; Fujii, Kanichi*; Yamamoto, Tetsuya*; Yoshida, Hideto*

Chemical Engineering Journal, 211-212, p.1 - 8, 2012/11

 Times Cited Count:8 Percentile:58.73(Engineering, Environmental)

The process for synthesizing metallic oxide powders by the microwave denitration method was investigated using hexahydrated nickel nitrate and trihydrated copper nitrate aqueous solutions, and the electrical field and the temperature distributions in the reactor were numerically simulated. Although CuO powder can be obtained from a trihydrated copper nitrate aqueous solution by the microwave denitration method, a hexahydrated nickel nitrate aqueous solution cannot be heated up to over 270 $$^{circ}$$C by microwave irradiation. It was also found that the reaction routes for microwave heating are the same as those for conventional external heating. This finding indicates that the success of producing oxide particles by microwave denitration depends not only on the microwave absorptivity of the intermediate and the metallic oxide, but also on the temperature difference.

JAEA Reports

Status and future plan of research and development on partitioning and transmutation technology for long-lived nuclides in JAERI

Oigawa, Hiroyuki; Nishihara, Kenji; Minato, Kazuo; Kimura, Takaumi; Arai, Yasuo; Morita, Yasuji; Nakayama, Shinichi; Katakura, Junichi

JAERI-Review 2005-043, 193 Pages, 2005/09

JAERI-Review-2005-043.pdf:16.13MB

JAERI has been conducting research and development on partitioning and transmutation (P&T) technology for long-lived nuclides to develop the double-strata fuel cycle concept, in accordance with the Atomic Energy Commission's "Research and Development of Technologies for Partitioning and Transmutation of Long-lived Nuclides - Status and Evaluation Report" issued in 2000. The double-strata fuel cycle concept consists of four major processes: partitioning, fuel fabrication, transmutation, and fuel processing. The five-year achievement and future perspectives for the technology on these processes are presented in this report. It also provides an analytical study on impacts of introducing P&T technology on waste management, and on deployment of P&T for the future nuclear energy system.

JAEA Reports

Example of answers to the problems of the 37th examination for the chief engineer of nuclear fuel, 2005

Harada, Akio; Sato, Tadashi*; Nakajima, Kunihisa; Komuro, Yuichi; Shiraishi, Hirotsugu*; Hattori, Takamitsu; Ikuta, Yuko; Yachi, Shigeyasu; Kushita, Kohei

JAERI-Review 2005-026, 55 Pages, 2005/09

JAERI-Review-2005-026.pdf:1.95MB

This report provides an example of answers to the problems of the 37th Examination for the Chief Engineer of Nuclear Fuel. This examination was done as a national qualification in March 2005. Brief explanations or references are added to some answers.

JAEA Reports

Summary report of the 7th Reduced-Moderation Water Reactor Workshop; March 5, 2004, JAERI, Tokai

Akie, Hiroshi; Nabeshima, Kunihiko; Uchikawa, Sadao

JAERI-Conf 2005-009, 153 Pages, 2005/08

JAERI-Conf-2005-009.pdf:14.7MB

As a research on the future innovative water reactor, the development of Reduced-Moderation Water Reactors (RMWRs) has been performed in JAERI. The workshop on RMWRs is aiming at information exchange between JAERI and other organizations, and has been held every year since 1998. The program of the 7th workshop was composed of 5 lectures and an overall discussion time. This report includes the original papers presented at the workshop and summaries of the questions and answers for each lecture as well as of the discussion time. In addition in Appendix, there are included presentation handouts of each lecture.

797 (Records 1-20 displayed on this page)