Treatment of electric hydraulic control fluid (EHC Oil) with steam-reforming system

Okadome, Yoshihiro; Aoyama, Yoshio; Sasaki, Yu; Fukushima, Mineo

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04

Investigation of a LiCl-KCl-UCl system using a combination of X-ray diffraction and differential thermal analyses

Nakayoshi, Akira; Kitawaki, Shinichi; Fukushima, Mineo; Murakami, Tsuyoshi*; Kurata, Masaki

Journal of Nuclear Materials, 441(1-3), p.468 - 472, 2013/10

https://doi.org/10.1016/j.jnucmat.2013.06.019

Electrorefining is one of the main steps of pyroreprocessing where spent nuclear fuels are recycled. Electrorefining is conducted in a molten salt of LiCl-KCl eutectic (59:41 mol%) containing actinide chlorides (AnCl) at 773 K. In order to operate and maintain the electrorefiner, it is necessary to accumulate fundamental data on LiCl-KCl-AnCl salt such as the melting point. In this study, based on X-ray diffraction and differential thermal analysis, a partial phase diagram of (LiCl-KCl)eut.-UCl pseudo-binary system and partial phase diagram of LiCl-KCl-UCl system were developed, which UCl concentration was up to 20 mol%.

Radiological emergency response to Fukushima Daiichi Accident; Teleoperation & robotics of JAEA

Fukushima, Mineo; Kawatsuma, Shinji; Okada, Takashi

Proceedings of American Nuclear Society Embedded Topical on Decommissioning, Decontamination and Reutilization and Technology Expo (DD&R 2012) (DVD-ROM), p.67 - 68, 2012/06

The accident on Fukushima Daiichi Nuclear Power Plant has been occurred by the TSUNAMI that generated form Great East Japan Earthquake happened in 11th March 2011. Just after the earthquake, JAEA is assisting activities concerning the accident of the Fukushima No.1 Nuclear Power Station including teleoperation, decontamination and radiation monitoring in the site. JAEA had already developed some robotics, RESQ series, for radiological emergency response in 2001, after JCO criticality accidents occurred. However, they could not work for the NPP because of lack of maintenance. According to the situation and condition of the FUKUSHIMA-DAIICHI accident, JAEA has modified above mentioned robotics and prepared supporting equipments like as Robotics control vehicles. JAEA has provided Robotics and Robotics Control vehicles to TEPCO and is continuously supporting Tokyo Electric Company for plant restoration.

Absorption spectra and cyclic voltammograms of uranium species in molten lithium molybdate-sodium molybdate eutectic at 550 C

Nagai, Takayuki; Uehara, Akihiro*; Fukushima, Mineo; Myochin, Munetaka; Fujii, Toshiyuki*; Sato, Nobuaki*; Yamana, Hajimu*

Proceedings in Radiochemistry, 1(1), p.151 - 155, 2011/09

http://www.oldenbourg-link.com/doi/abs/10.1524/rcpr.2011.0012

Absorption spectra of dissolved uranium species in molten LiMoO-NaMoO eutectic at 550 C were measured by spectrophotometry, and their redox reactions were also investigated by cyclic voltammetry. Observed absorption spectra of uranium species were similar to those of UO in molten chlorides. After purging oxygen into the melt, the absorption peaks of UO decreased and UO was thought to be oxidized to UO. When the uranium species were not contained in the melt, we confirmed that alkali metals deposited at -0.7 V and a small reduction of this melt was observed at -0.3 V. When UO was dissolved into the melt, the reduction of the uranium species was observed at -0.2 V. It was suggested that the dissolved uranium species are recovered as mixed uranium-molybdenum oxides by electrolysis.

Anodic behaviour of a metallic U-Pu-Zr alloy during electrorefining process

Murakami, Tsuyoshi*; Sakamura, Yoshiharu*; Akiyama, Naoyuki*; Kitawaki, Shinichi; Nakayoshi, Akira; Fukushima, Mineo

Journal of Nuclear Materials, 414(2), p.194 - 199, 2011/07

https://doi.org/10.1016/j.jnucmat.2011.03.009

An electrorefining is one of the main steps of pyrochemical reprocessing of spent metallic fuels (U-Zr, U-Pu-Zr). The electrorefining is carried out dissolving a portion of Zr together with actinides to accomplish a high dissolution ratio of actinides. However, the electrorefining with Zr co-dissolution should bring some practical problems in the pyrochemical reprocessing. Therefore, electrorefining tests of non-irradiated U-Pu-Zr alloy were performed with minimizing the amount of Zr dissolved in LiCl-KCl-(U, Pu, Am)Cl melts at 773 K. The tests were performed both by potentiostatic electrolysis at -1.0 V (Ag/Ag) that was more negative than the Zr dissolution potential and by galvanostatic electrolysis with a limited amount of Zr dissolution. The ICP-AES analysis of the anode residues confirmed that a high dissolution ratio of actinides (U; 99.6%, Pu; 99.9%) was successfully demonstrated at both electrolyses.

Recent progress of JAEA-CRIEPI joint study for metal pyroreprocessing at CPF

Kitawaki, Shinichi; Nakayoshi, Akira; Fukushima, Mineo; Koizumi, Tsutomu; Kurata, Masaki*; Yahagi, Noboru*

Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.1269 - 1273, 2009/09

JAEA is developing the pyroreprocessing by collaboration with CRIEPI. The test using U began in 2002, and the test using PuO and unirradiated MOX were ended in 2008. The reduction of UO pellets by using Li-reduction method, the electrowinning using reduced pellets, the separation of adhered salt with deposit by distillation, and the ingot formation of deposit were performed. As a result, 99% of the loaded U is recovered as metal ingot. The tests similar to U tests were performed by using PuO. As a result, Pu was successfully recovered with U metal. In the MOX test, the mass balance of Pu was maintained at 100% with respect to the initial amount. We try to form the U-Pu-Zr alloy by using reduced MOX. After 2009, the process development that uses the alloy will be continued.

Recovery of U-Pu alloy from MOX using a pyroprocess series

Kitawaki, Shinichi; Shinozaki, Tadahiro; Fukushima, Mineo; Usami, Tsuyoshi*; Yahagi, Noboru*; Kurata, Masaki*

Nuclear Technology, 162(2), p.118 - 123, 2008/05

https://doi.org/10.13182/NT08-A3937

A series test of pyro-process was carried out to recover U-Pu alloy from MONJU MOX pellets. In the Li-reduction step, the reduction behavior of MOX was similar to that of UO. In the electrorefining step, the separation factor between U and Pu was 5.7 for the combination of reduced MOX anode and liquid cadmium cathode, which is almost comparable to the value in the previous studies. For the material balance, approximately 98% of U and 103% of Pu were detected in the electrodes or molten salt after the electrolysis with respect to the initial amounts in the anode or molten salt. Considering the analytical error of ICP-AES, these values are reasonable. The remained amount of U in the anode was slightly larger than that of Pu due to the re-oxidation. The U-Pu alloy ingot was successfully formed by distillation of Cd.

Pyro-chemical reprocessing using molybdate melt chemical and electrochemical behaviors of uranium oxides in NaMoO melt

Mizuguchi, Koji; Yasuike, Yoshiyuki*; Fukushima, Mineo; Myochin, Munetaka

Nihon Genshiryoku Gakkai Wabun Rombunshi, 6(4), p.484 - 490, 2007/12

https://doi.org/10.3327/taesj.J06.070

We develop a new decladding process which integrates with dissolution using the molybdenum oxide melt. This melt possesses characteristics that can make actinide oxide dissolve at high speed without reacting with metal such as the cladding tube. To construct the new process, it is necessary to clarify the reaction mechanisms of uranium in dissolution, oxidation, and electrolysis in this melt. In this study, the gram-scale uranium examination was carried out, and the reaction mechanism of the uranium in the melt was clarified. In NaMoO - NaMoO melts, uranium dioxide dissolves as NaU(MoO) without changing its oxidation number. In the oxidation, uranium valence was oxidized from IV to VI with oxygen. In electrolysis process, it was clarified that the low current efficiency was caused by the re-dissolution of deposit. The granulated UO was recovered on the cathode by adjusting the temperature of the melt to 700 degrees centigrade at which re-dissolution was reduced.

Integrated experiments of electrometallurgical pyroprocessing with using plutonium oxide

Koyama, Tadafumi*; Hijikata, Takatoshi*; Usami, Tsuyoshi*; Inoue, Tadashi*; Kitawaki, Shinichi; Shinozaki, Tadahiro; Fukushima, Mineo; Myochin, Munetaka

Journal of Nuclear Science and Technology, 44(3), p.382 - 392, 2007/03

https://doi.org/10.3327/jnst.44.382

Electrometallurgical pyroprocessing is a promising technology to realize actinide fuel cycle. Integrated experiments to demonstrate electrometallurgical pyroprocessing of plutonium oxide in continuous operation were carried out. In each test, 10 to 20 g of PuO was reacted with Li reductant to form metal product. The reduction products were charged in the anode basket of the electrorefiner with LiCl-KCl-UCl electrolyte. With using the anodes, deposition of uranium on the solid cathode was carried out, when PuCl concentration was low. After Pu/U ratio in salt electrolyte was increased enough, plutonium and uranium were recovered simultaneously on the liquid cadmium cathode. By heating up the deposits for distillation of the salt and the cadmium, U metal or Pu-U alloyed metal were obtained as residues in the crucible. It was first result to demonstrate the recovery of metal actinides in the continuous operation of pyroprocessing of oxide fuels.

Recovery test of metal product from oxide fuel by electrometallurgical pyroprocess

Kitawaki, Shininchi; Shinozaki, Tadahiro; Fukushima, Mineo; Hijikata, Takatoshi*; Usami, Tsuyoshi*; Koyama, Tadafumi*

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 5 Pages, 2005/10

Electrometallurgical pyroprocess is a key innovative technology to realize closed actinides cycle with keeping high proliferation-resistance and economy. JNC and CRIEPI have been carrying out the integrated tests of electrometallurgical reprocessing of metal and oxide Pu-containing fuel to demonstrate whole process in continuous operation. After intensive cold test to confirm the functions of experimental apparatus and the test conditions, recovery test of actinide metal product from actinide oxide fuels has started as a first series of the integrated tests. In this report, result of the recovery test is described to elucidate the material flow in the process.