Development of density control technologies for MOX pellet using dry recycled powders

Nishina, Masahiro; Takeuchi, Kentaro; Murakami, Shinichi

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 8 Pages, 2022/04

no abstracts in English

Effect of particle properties on die filling behavior in nuclear oxide fuel pellet production

Akashi, Masatoshi; Nishina, Masahiro; Kato, Masato; Tanaka, Tatsuya*; Shimosaka, Atsuko*; Shirakawa, Yoshiyuki*; Hidaka, Jusuke*

no journal, , 

Study on development of additive-free dry granulation technology and evaluation of granulation characteristics

Ishii, Katsunori; Segawa, Tomoomi; Kawaguchi, Koichi; Nishina, Masahiro; Makino, Takayoshi; Natori, Yuri*

no journal, , 

JAEA is developing simplified a plutonium and uranium mixed oxide (MOX) pellet fabrication process. In this process, agitation granulator improves flowability of MOX powder with water as binder. This granulation method has issues, including low production capacity due to criticality control for wet nuclear material. A new simple additive-free dry granulation method was proposed recently to produce tritium breeding LiO spheres for nuclear fusion reactor. In this research, results of experiments to investigate the applicability of the new granulation method to MOX powder is reported.

Evaluation of the effects of granulated alumina powder characteristics and die wall lubricant on compaction behavior using X-ray computed tomography

Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Nishina, Masahiro; Makino, Takayoshi; Iimura, Kenji*; Satone, Hiroshi*; Suzuki, Michitaka*; Natori, Yuri*

no journal, , 

Japan Atomic Energy Agency has developed a simplified pelletizing fuel fabrication system. In this system, the flowability of a MOX raw powder is improved by wet granulation for the pelletizing process, and the die wall lubrication method directly presses the granulated MOX powder into green pellets without adding any lubricant into the powder. The homogeneous compression is important to fabricate high-density green pellets. However, it is difficult to observe the compaction behavior in situ. Therefore, the capping phenomenon was investigated by using X-ray computed tomography and alumina powder that is highly transparent against X-rays. When lubricant was used, the breakage of the particles extended to the bottom compared with not used. This result indicates that the die wall lubrication is effective for the homogeneous compression of granulated powders.

Sintering behavior of MOX pellets prepared by mechanical blending method

Nishina, Masahiro; Suzuki, Kiichi; Takeuchi, Kentaro; Kato, Masato; Uno, Hiroki*

no journal, , 

Sintering behavior of MOX pellets prepared by the mechanical blending method was evaluated from measurement results of the O/M ratio and dimensional shrinkage of the pellets during sintering. Change of the O/M ratio occurred when approaching the equilibrium condition which was decided from oxygen potential depending on the P/P ratio in the sintering atmosphere. The O/M ratio increased and the MOX pellets shrank at lower temperatures with decreasing P/P ratio. The MOX pellets sintered near O/M = 2.0 showed more homogeneous distribution of uranium and plutonium than those of other specimens.

Study on the condition of MOX granules suitable for constant die filling in MOX fuel pellet production

Akashi, Masatoshi; Nishina, Masahiro; Morimoto, Kyoichi; Kato, Yoshiyuki; Kato, Masato

no journal, , 

A die filling experiment was carried out using granulated MOX powder to investigate the condition of MOX granules suitable for constant die filling. It was found that the mean particle diameter and the Hausner ratio gave an indication of the die filling for the granulated MOX powder.