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Journal Articles

Property measurements of (U$$_{0.7}$$,Pu$$_{0.3}$$)O$$_{2-x}$$ in $$P$$$$_{O2}$$-controlled atmosphere

Kato, Masato; Murakami, Tatsutoshi; Sunaoshi, Takeo*; Nelson, A. T.*; McClellan, K.*

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.852 - 856, 2013/09

Uranium and plutonium mixed oxide (U$$_{0.7}$$,Pu$$_{0.3}$$)O$$_{2-x}$$ which has been developed as a fast reactor fuel is nonstoichiometric compound. The stoichiometry significantly affects various properties. The relationship between oxygen potential and oxygen-to-metal (O/M) ratio has been investigated so far. The measurement results showed that it is essential to control oxygen partial pressure ($$P$$$$_{O2}$$) for holding constant O/M ratio in high temperature range. Therefore, properties of (U$$_{0.7}$$,Pu$$_{0.3}$$)O$$_{2-x}$$ were measured in $$P$$$$_{O2}$$-controlled atmosphere in this work. In this work, properties of O/M change, sintering and thermal expansion were investigated in $$P$$$$_{O2}$$-controlled atmosphere.

Journal Articles

Study of feasible and sustainable multilateral approach on nuclear fuel cycle

Kuno, Yusuke; Tazaki, Makiko; Akiba, Mitsunori*; Adachi, Takeo*; Takashima, Ryuta*; Izumi, Yoshinori*; Tanaka, Satoru*

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.965 - 974, 2013/09

Multilateral Nuclear Approach (MNA) provides services on the frontend and the backend to the states possessing nuclear power plants with nuclear non-proliferation measures and without interfering with the inalienable right in NPT may be one of the most effective and efficient manners for peaceful use of nuclear energy. Recent MNA discussions tend to focus on reliable fuel supply, namely front-end of NFC, where proliferation of uranium enrichment can be deterred. At the same time, the MNA capability to provide assurance/service that the Spent Fuel be managed properly is actually more important. In this work a regional MNA framework was studied to fulfil the above mentioned points.

Journal Articles

Plutonium partitioning in uranium and plutonium co-recovery system for fast reactor fuel recycling with enhanced nuclear proliferation resistance

Nakahara, Masaumi; Koma, Yoshikazu; Nakajima, Yasuo

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.539 - 542, 2013/09

In order to develop a fast reactor fuel reprocessing, countercurrent extraction experiments for Pu reduction partitioning method with hydroxylamine nitrate and acid split method without Pu reductant were carried out. In the Pu reduction method, a part of U was co-recovered with Pu because the U scrubbing part can be deleted in the Pu partitioning section. On the other hand, acid split method experimental results indicate that almost all Pu was recovered with U by supplying diluted HNO$$_{3}$$ solution in the Pu partitioning section. This study shows that not only Pu reduction partitioning but also acid split methods are effective for fast reactor fuel reprocessing.

Journal Articles

Suggestion of typical phases of in-vessel fuel-debris by thermodynamic calculation for decommissioning technology of Fukushima-Daiichi Nuclear Power Station

Ikeuchi, Hirotomo; Kondo, Yoshikazu*; Noguchi, Yoshihiro*; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1349 - 1356, 2013/09

Journal Articles

Major safety and operational concerns for fuel debris criticality control

Tonoike, Kotaro; Sono, Hiroki; Umeda, Miki; Yamane, Yuichi; Kugo, Teruhiko; Suyama, Kenya

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.729 - 735, 2013/09

JAEA is conducting studies on criticality control of the fuel debris formed in the accident of Fukushima-Daiichi site. A new control principle must be established, referring principles for existing facilities, and based on criticality characteristics of the debris. In accordance with the principle, safe and practical control has to be realized for the debris whose condition is uncertain at present. This report outlines the present condition of debris and Fukushima site, introduces examples of criticality analysis, and discusses control principles. Research subjects are also proposed to realize the control.

Journal Articles

Direction on characterization of fuel debris for defueling process in Fukushima Daiichi Nuclear Power Station

Yano, Kimihiko; Kitagaki, Toru; Ikeuchi, Hirotomo; Wakui, Ryohei; Higuchi, Hidetoshi; Kaji, Naoya; Koizumi, Kenji; Washiya, Tadahiro

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1554 - 1559, 2013/09

Journal Articles

Research subjects for analytical estimation of core degradation at Fukushima-Daiichi Nuclear Power Plant

Nagase, Fumihisa; Ishikawa, Jun; Kurata, Masaki; Yoshida, Hiroyuki; Kaji, Yoshiyuki; Shibamoto, Yasuteru; Amaya, Masaki; Okumura, Keisuke; Katsuyama, Jinya

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.711 - 720, 2013/09

Estimation of the accident progress and status inside the reactor is required to properly and reliably conduct decommissioning of the Fukushima-Daiichi NPPs. For that, it is necessary to obtain additional experimental data and revised models for the estimation using computer codes with increased accuracies. JAEA has selected phenomena to be reviewed and developed in terms of thermo hydraulic behavior in the reactor, progression of fuel bundle degradation, failure of the lower head of the reactor pressure vessel, and analysis of the accident, considering previously obtained information, conditions specific to the Fukushima-Daiichi NPP accident, and recent progress of experimental and analytical technologies. This paper introduces the selected phenomena to be reviewed and developed and recent results from the JAEA's corresponding research programs.

Journal Articles

Study on release and transport of aerial radioactive materials in reprocessing plant

Amano, Yuki; Tashiro, Shinsuke; Uchiyama, Gunzo; Abe, Hitoshi; Yamane, Yuichi; Yoshida, Kazuo

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1411 - 1417, 2013/09

Journal Articles

Research and development on waste management for the Fukushima Daiichi NPS by JAEA

Koma, Yoshikazu; Ashida, Takashi; Meguro, Yoshihiro; Miyamoto, Yasuaki; Sasaki, Toshiki; Yamagishi, Isao; Kameo, Yutaka; Terada, Atsuhiko; Hiyama, Toshiaki; Koyama, Tomozo; et al.

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.736 - 743, 2013/09

Fukushima Daiichi Nuclear Power Station (F1NPS), TEPCO, was severely damaged with the hydrogen explosions caused by losing their cooling functions due to the earthquake and the tsunami occurred on March 11, 2011. Radioactive wastes generated from the current FINPS and future their decommission and demolition are greater huge amount than those from general reactors and nuclear fuel facilities. Toward accomplishing safe and reasonable management of the wastes, great effort of R&Ds has been strongly required and performed in bringing together the knowledge and experience of all of Japan. This report outlines the current status of the R&Ds performed in JAEA.

Journal Articles

Melting temperatures of the ZrO$$_{2}$$-MOX system

Uchida, Teppei; Hiroka, Shun; Sugata, Hiromasa*; Shibata, Katsuya*; Sato, Daisuke*; Kato, Masato; Morimoto, Kyoichi

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1549 - 1553, 2013/09

Journal Articles

Results of detailed analyses performed on boring cores extracted from the concrete floors of the Fukushima Daiichi Nuclear Power Plant reactor buildings

Maeda, Koji; Sasaki, Shinji; Kumai, Misaki; Sato, Isamu; Osaka, Masahiko; Fukushima, Mineo; Kawatsuma, Shinji; Goto, Tetsuo*; Sakai, Hitoshi*; Chigira, Takayuki*; et al.

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.272 - 277, 2013/09

Journal Articles

Recovery of minor actinides from spent fuel using TPEN-immobilized gels

Koyama, Shinichi; Suto, Mitsuo; Obayashi, Hiroshi; Oaki, Hiroshi*; Takeshita, Kenji*

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.549 - 553, 2013/09

A series of separation experiments was performed in order to study the recovery process for minor actinides (MAs) from the actual spent fuel by using an extraction chromatographic technique. The 10 mol% TPPEN-gel was used to improve adsorption coefficient of Am and a condition of eluent temperature was changed in order to confirm the temperature swing effect on TPEN-gel for MA. More than 90% Eu was detected in the eluent after washing with 0.01M NaNO$$_{3}$$ (pH 3.5) at 5$$^{circ}$$C. Americium was backwardly detected and eluted continuously during in the same condition. After removal of Eu, the eluent temperature was changed to 32$$^{circ}$$C, then Am was detected (pH 3.0). Finally remained Am could be stripped from TPPEN-gel by changing the pH of the eluent to 2.0.

Journal Articles

Mutual separation of Am/Cm/Ln by the use of novel-triamide, NTAamide and water-soluble diglycolamide

Sasaki, Yuji; Tsubata, Yasuhiro; Kitatsuji, Yoshihiro; Sugo, Yumi; Shirasu, Noriko; Morita, Yasuji

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.1079 - 1082, 2013/09

Mutual separation of Am, Cm and lanthanides (Ln) is important to develop the partitioning process of high-level radioactive liquid waste, because the application to their different disposal methods are advantageous. Namely, Am is studied for transmutation due to the reduction of long half-life radionuclides, Cm should be kept in interim storage in order to reduce the calorific value, and Ln should be present in the vitrified radioactive waste toward the geological disposal. However, this mutual separation method is difficult to establish because they have very similar chemical behavior, same oxidation state (III) and similar ionic radii. The development of their mutual separation is termed as the challenging study. In order to obtain the satisfactory results, the property of extractant requires the differentiation of actinide (An) from Ln, high preferability to different ionic radii between Am and Cm, and high extractability to hard acids. Therefore, the extractant have to include both N atom, whose soft donor has high selectivity between An and Ln, and O atoms for the strong extractability to An. The new extractant, NTAamide (N,N,N',N',N'',N''-hexaoctyl-nitrirotriacetamide) is a triamide having N donor at the center of backbone, then NTAamide has hybrid performance of complexation to metals by soft N and three hard amidic O atoms. It is clear that NTAamide can extract trivalent An at diluted HNO$$_{3}$$ with small D(Ln), the separation of An from Ln can be carried out at that condition. The SF of Am/Cm by NTAamide is approximate 1.8, which is not so high to separate each other. The combination of NTAamide of extractant and TEDGA (N,N,N',N'-tetraethyl-diglycolamide) as a masking agent in the aqueous phase shows very high SF(Am/Cm) of maximal 6.5. It is obvious that NTAamide is a promising extractant to achieve the mutual separation among Am/Cm/Ln.

Journal Articles

Environmental remediation following the Fukushima-Daiichi accident

Tagawa, Akihiro; Nakayama, Shinichi; Miyahara, Kaname

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.944 - 951, 2013/03

A wide area of Fukushima Prefecture was contaminated with radioactivity released by the Fukushima Daiichi nuclear accident. Japan Atomic Energy Agency (JAEA) has been involved in mitigating the effects of the accident in a diversifying ways from the emergency dispatch of radiation experts immediately after the accident and radiation monitoring in the affected areas to demonstrate of decontamination for a variety of targets, public affairs with evacuated populations, and research and development activities for environmental remediation. The decontamination related activity is one of the major contributions of JAEA to environmental remediation, providing technical supports to the unprecedented regional decontamination in Fukushima that have been carried out by the central and local governments of Japan. JAEA's experiences and expertise obtained are overviewed in this paper focusing on the decontamination pilot project.

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