Effect of decay heat on pyrochemical reprocessing of minor actinide transmutation nitride fuels

Hayashi, Hirokazu; Tsubata, Yasuhiro; Sato, Takumi

Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(3), p.97 - 107, 2023/08

https://doi.org/10.3327/taesj.J22.009

The Japan Atomic Energy Agency has chosen nitride fuel as the first candidate for the transmutation of long-lived minor actinides (MA) using accelerator-driven systems (ADS). The pyrochemical method has been considered for reprocessing spent MA nitride fuels, because their decay heat should be very large for aqueous reprocessing. This study was conducted to investigate the effect of decay heat on the pyrochemical reprocessing of MA nitride fuels. On the basis of the estimated decay heats and the temperature limits of the materials that are to be handled in pyrochemical reprocessing, quantities adequate for handling in argon gas atmosphere were evaluated. From these considerations, we proposed that an electrorefiner with a diameter of 26 cm comprising 12 cadmium (Cd) cathodes with a diameter of 4 cm is suitable. On the basis of the size of the electrorefiner, the number necessary to reprocess spent MA fuels from 1 ADS in 200 days was evaluated to be 25. Furthermore, the amount of Cd-actinides (An) alloy to produce An nitrides by the nitridation-distillation combined reaction process was proposed to be about one-quarter that of Cd-An cathode material. The evaluated sizes and required numbers of equipment support the feasibility of pyrochemical reprocessing for MA nitride fuels.

Formation of MPd (M = Gd, Np) by the reaction of MN with Pd and chlorination of MPd using cadmium chloride

Hayashi, Hirokazu; Shibata, Hiroki; Sato, Takumi; Otobe, Haruyoshi

Journal of Radioanalytical and Nuclear Chemistry, 332(2), p.503 - 510, 2023/02

https://doi.org/10.1007/s10967-023-08760-4

The formation of MPd (M = Gd, Np) by the reaction of MN with Pd at 1323 K in Ar gas flow was observed. Cubic AuCu-type GdPd ( = 0.4081 0.0001 nm) and NpPd ( = 0.4081 0.0001 nm) were identified, respectively. The product obtained from the reaction of NpN with Pd contained additional phases including the hexagonal TiNi-type NpPd. Chlorination of the MPd (M = Gd, Np) samples was accomplished by the solid-state reaction using cadmium chloride at 673 K in a dynamic vacuum. Pd-rich solid solution phase saturated with Cd and an intermetallic compound PdCd were obtained as by-products of MCl formation.

Current status and future plan of research and development on partitioning and transmutation based on double-strata concept in JAEA

Tsujimoto, Kazufumi; Sasa, Toshinobu; Maekawa, Fujio; Matsumura, Tatsuro; Hayashi, Hirokazu; Kurata, Masaki; Morita, Yasuji; Oigawa, Hiroyuki

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.657 - 663, 2015/09

To continue the utilization of the nuclear fission energy, the management of the high-level radioactive waste is one of the most important issues to be solved. Partitioning and Transmutation technology of HLW is expected to be effective to mitigate the burden of the HLW disposal by reducing the radiological toxicity and heat generation. The Japan Atomic Energy Agency (JAEA) has been conducting the research and development on accelerator-driven subcritical system (ADS) as a dedicated system for the transmutation of long-lived radioactive nuclides. This paper overviews the recent progress and future R&D plan of the study on the ADS and related fuel cycle technology in JAEA.

Nuclear energy and waste management; Pyroprocess for system symbiosis

Ogawa, Toru; Minato, Kazuo; Okamoto, Yoshihiro; Nishihara, Kenji

Journal of Nuclear Materials, 360(1), p.12 - 15, 2007/01

https://doi.org/10.1016/j.jnucmat.2006.08.019

The actinide management has become a key issue in nuclear energy due to increasing proliferation concern and long-term environmental perception. The better way of waste management will be made by system symbiosis: a combination of light-water reactor and fast reactor and/or accelerator-driven transmutation system should be sought. The new recycling technology should be able to achieve good economy with smaller plants, which can process fuels from different types of reactors on a common technical basis. Pyroprocess with the use of molten salts is regarded as the strong candidate for such recycling technology. In JAEA, the first laboratory for the high temperature chemistry of transuranium elements, mainly Am and Cm, has been established. The fundamental data on the molten-salt chemistry of transuranium oxides and nitrides will be combined with the computer code for predicting the molten-salts electrolytic processes.

Development of module for TRU high temperature chemistry (Joint research)

Minato, Kazuo; Akabori, Mitsuo; Tsuboi, Takashi; Kurobane, Shiro; Hayashi, Hirokazu; Takano, Masahide; Otobe, Haruyoshi; Misumi, Masahiro*; Sakamoto, Takuya*; Kato, Isao*; et al.

JAERI-Tech 2005-059, 61 Pages, 2005/09

JAERI-Tech-2005-059.pdf:20.67MB

An experimental facility called the Module for TRU High Temperature Chemistry (TRU-HITEC) was installed in the Back-end Cycle Key Elements Research Facility (BECKY) of the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) for the basic studies of the behavior of the transuranium elements (TRU) in pyrochemical reprocessing and oxide fuels. TRU-HITEC consists of three alpha/gamma cells shielded by steel and polyethylene and a glove box shielded by leaded acrylic resin, where experimental apparatuses have been equipped and a high purity argon gas atmosphere is maintained. In the facility 10 g of Am as well as the other TRU of Np, Pu and Cm can be handled. This report summarizes the outline, structure, performance and interior apparatuses of the facility, and is the result of the joint research between the Japan Atomic Energy Research Institute and three electric power companies of Tokyo Electric Power Co., Tohoku Electric Power Co. and the Japan Atomic Power Co.

Proceedings of the 3rd Workshop on Molten Salts Technology and Computer Simulation

Okamoto, Yoshihiro; Minato, Kazuo

JAERI-Conf 2004-008, 228 Pages, 2004/04

JAERI-Conf-2004-008.pdf:17.05MB

Applications of molten salts technology to separation and synthesis of materials have a potential to give us a civilized life, for example aluminium refinement. Recently, much attention is given to the pyrochemical reprocessing of spent nuclear fuels in the molten salt research field. On the other hand, computer simulation technique is expected to play an important role for supporting experimental works and predicting unknown physical properties in the molten salts application studies. Research group for Actinides Science, Department of Materials Science, Japan Atomic Energy Research Institute(JAERI), together with Reprocessing and Recycle Technology Division, Atomic Energy Society of Japan, organized the 3rd Workshop on Molten Salts Technology and Computer Simulation at Tokai Research Establishment, JAERI on December 16, 2003. Many molten salts researchers in Japan participated in the workshop and many useful presentations and discussions were performed.

Proceedings of the 2nd Workshop on Molten Salts Technology and Computer Simulation

Okamoto, Yoshihiro; Minato, Kazuo

JAERI-Conf 2003-005, 186 Pages, 2003/06

JAERI-Conf-2003-005.pdf:10.42MB

Applications of molten salts technology to separation and synthesis of materials have been widely studied. Especially, much attention is given to the pyrochemical reprocessing of spent nuclear fuels. Computer simulation technique is expected to play an important role for supporting experimental works and predicting unknown physical properties in the molten salts application studies. Research group for Actinides Science, Department of Materials Science, Japan Atomic Energy Research Institute (JAERI), together with Reprocessing and Recycle Technology Division, Atomic Energy Society of Japan, organized the 2nd Workshop on Molten Salts Technology and Computer Simulation at Tokai Research Establishment, JAERI on December 3, 2002. Many molten salts researchers in Japan participated in the workshop and many useful presentations and discussions were performed.

Present status and approach on advanced technologies of nuclear fuel, 3; Research and development of advanced recycle technology

Arie, Kazuo*; Abe, Tomoyuki*; Arai, Yasuo

Nihon Genshiryoku Gakkai-Shi, 44(8), p.593 - 599, 2002/08

http://ci.nii.ac.jp/naid/10009430661

no abstracts in English

Radioactive wastes generated from JAERI partitioning-transmutation cycle system

Nakayama, Shinichi; Morita, Yasuji; Nishihara, Kenji

Proceedings of International Conference on Back-End of the Fuel Cycle: From Research to Solutions (GLOBAL 2001) (CD-ROM), 6 Pages, 2001/09

Production of lower-level radioactive wastes, as well as the reduction in radioactivity of HLW, is an important performance indicator in assessing the viability of a partitioning-transmutation system. We have begun to identify the chemical compositions and to quantify the amounts of radioactive wastes that may be generated by JAERI's processes. Long-lived radionuclides such as C and Ni and spallation products of Pb-Bi coolants such as Po (10 Bq/yr) are added to the existing inventory of these nuclides that are generated in the current fuel cycle. Spent salts of KCl-LiCl, which is not generated from the current fuel cycle, will be introduced as a waste.

Radioactive wastes generated from JAERI partitioning-transmutation cycle system

Nakayama, Shinichi; Morita, Yasuji; Nishihara, Kenji

Proceedings of International Conference on Back-End of the Fuel Cycle: From Research to Solutions (GLOBAL 2001) (CD-ROM), 6 Pages, 2001/00

no abstracts in English