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Takeuchi, Masayuki; Arai, Yoichi; Kase, Takeshi; Koizumi, Tsutomu
Proceedings of International Symposium on EcoTopia Science 2007 (ISETS '07) (CD-ROM), p.1084 - 1088, 2007/11
Pyrochemical reprocessing methods using molten salt for spent nuclear fuel have been studied in the world, because of advantage over the nuclear weapons proliferation and cost benefit. However, electrowinning process, which is one of the processes in pyrochemical reprocessing method, includes severe corrosion environment. In this study, the efficacy of cold crucible in electrowinning process was experimentally discussed. We carried out the corrosion test of several metals in molten 2CsCl-NaCl with corrosive gases at 923 K to investigate the relationship between material temperature controlled by air cool and corrosion rate. As results, the corrosion rate of hastelloy alloy was less than 0.1 mm/y by cooling the material surface at 473 K and corresponds to 1/1000 of that at 923 K. In such way, the cold crucible gives the extreme improvement of corrosion, and this result gave promising prospect to solve the corrosion problem in electrowinning process.
Nomura, Kazunori; Nakahara, Masaumi; Yano, Kimihiko; Sano, Yuichi; Shibata, Atsuhiro; Washiya, Tadahiro
Proceedings of International Symposium on EcoTopia Science 2007 (ISETS '07) (CD-ROM), p.1058 - 1061, 2007/11
Matsunami, Noriaki*; Nakano, Tomohide
Proceedings of International Symposium on EcoTopia Science 2007 (ISETS '07) (CD-ROM), p.321 - 322, 2007/11
Meguro, Yoshihiro; Tomioka, Osamu; Yamaguchi, Hiromi; Takahashi, Kuniaki
Proceedings of International Symposium on EcoTopia Science 2007 (ISETS '07) (CD-ROM), p.1043 - 1046, 2007/11
In order to lower the cost of the disposal of low-level radioactive waste, several waste treatment technologies, such as reduction of radioactive concentration in the waste, reduction in amount of the waste, and removal of harmful materials for the disposal, are essential. The authors have developed four waste treatment technologies; these are a supercritical CO
fluid decontamination method, a calcination method, a chemical reductive denitration method, and a steam reforming method in JAEA. It was demonstrated that these methods showed promise for the waste treatment.
Nakayoshi, Akira; Kitawaki, Shinichi; Fukushima, Mineo; Kurata, Masaki*; Yahagi, Noboru*
Proceedings of International Symposium on EcoTopia Science 2007 (ISETS '07) (CD-ROM), p.1062 - 1066, 2007/11
Pyro-reprocessing is one of the promising reprocessing methods for recycling spent nuclear fuels generated from fast reactors. Comparing to the conventional aqueous-processes, following benefits are expected when introducing the pyro-reprocessing, such as reduction of environmental burden, enhancement of proliferation-resistant, enhancement of economical potential, efficient utilization of nuclear resources. The pyro-reprocessing will therefore become more attractive not only in developed countries regarding nuclear energy, but also in developing countries. As for reducing environmental burden, the most important subject is establishment of the nuclear fuel cycle, in which actinide elements are closed. Various kinds of intermediate waste which contains actinide elements are formed in the practical operation not only from the main steps of the pyro-reprocessing but also from related sub-streams.