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Goto, Yuichi; Suzuki, Yoshimasa; Horigome, Kazushi; Miyamoto, Toshihiko*; Usui, Masato*; Mori, Eito*; Kuno, Takehiko
JAEA-Technology 2022-005, 42 Pages, 2022/07
JAEA-Technology-2022-005.pdf:4.48MB
Radioactive wastes were generated and stored in the hot cell of Operation Testing Laboratory of Tokai Reprocessing Plant due to the experiments related to the reprocessing technology development from 1974 to 2014. Waste removal work was strengthened by the shift work in the past, however another wastes were generated by the equipment dismantling. From 2006, an improved waste removal method was established by using bag-out technique and wastes were taken from the glove-box connected to the hot cell. The removal period, estimated from the conventional method using Cask No. 10, was reduced from 14 to 5 years. From 2016, upgrade of worker's awareness including related departments was performed by various software and hardware improvements. Also, the worker's skills were improved and equipment in Cask No.10 was checked for preventive maintenance. The prevention measures for past troubles were discussed with Radiation Control Department. In addition, transportation schedule including safety operation with Transportation Department and Waste Receiving Department was optimized to maintain the waste removal cycle. The removal period was reduced from 5 to 3 years by the above efforts. Finally, the work was completed in March 2020.
Asami, Makoto*; Takahatake, Yoko; Myodo, Masato; Tobita, Takeshi; Kobayashi, Kiwami; Hayakawa, Misa; Usui, Yuka; Watahiki, Hiromi; Shibata, Atsuhiro; Nomura, Kazunori; et al.
JAEA-Data/Code 2017-001, 78 Pages, 2017/03
JAEA-Data-Code-2017-001.pdf:4.92MB
JAEA-Data-Code-2017-001-appendix(DVD-ROM).zip:818.06MB
At Fukushima Daiichi Nuclear Power Station owned by Tokyo Electric Power Company Holdings, Incorporated (TEPCO), contaminated water (accumulated, treated) secondary waste from water treatment, rubble and soil were collected and analyzed. The data already opened to public was collected as this report. The analytical data reported by TEPCO, Japan Atomic Energy Agency and International Research Institute for Nuclear Decommissioning until the end of March, 2016, was collected. Information on the samples and values of radioactive nuclide concentration and others were tabulated, besides figures, which show change in radioactive nuclide concentration for major nuclides, are contained. And, English translation and the collected data are provided as electric data.
Terunuma, Akihiro; Mimura, Ryuji; Nagashima, Hisao; Aoyagi, Yoshitaka; Hirokawa, Katsunori*; Uta, Masato; Ishimori, Yuu; Kuwabara, Jun; Okamoto, Hisato; Kimura, Yasuhisa; et al.
JAEA-Review 2016-008, 98 Pages, 2016/07
JAEA-Review-2016-008.pdf:11.73MB
Japan Atomic Energy Agency formulated the plan to achieve the medium-term target in the period of April 2010 to March 2015(hereinafter referred to as "the second medium-term plan"). JAEA determined the plan for the business operations of each year (hereinafter referred to as "the year plan"). This report is that the Sector of Decommissioning and Radioactive Waste Management has summarized the results of the decommissioning technology development and decommissioning of nuclear facilities which were carried out in the second medium-term plan.
Tachibana, Mitsuo; Murata, Masato; Tasaki, Tadayuki; Usui, Hideo; Kubota, Shintaro
Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1987 - 1996, 2015/09
230 various types of nuclear facilities were constructed in JAEA's R&D Institutes or Center until the establishment of the JAEA in 2005. The JAEA has efficiently and systematically decommissioned nuclear facilities that would no longer be required after the establishment of the JAEA. Decommissioning of nuclear facilities in each JAEA's R&D Institutes or Center was continued based on the second midterm plan of the JAEA from FY2010 to FY2014. Decommissioning of 2 nuclear facilities was completed during the second midterm. This report describes current status of decommissioning activities in the JAEA during the second midterm and outline of the decommissioning plan in the third midterm.
-like spin resonance in the iron-based nodal superconductor BaFe
(As
P
) observed using inelastic neutron scatteringIshikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.
Physical Review B, 84(14), p.144517_1 - 144517_5, 2011/10
Times Cited Count：26 Percentile：70.69(Materials Science, Multidisciplinary)We performed inelastic neutron scattering on a powder sample of iron-based superconductor BaFe(AsP) with 
= 30 K. Although this system is expected to have line nodes in its superconducting order parameter, we have observed spin resonance at the same scattering vector as that appeared in the -wave iron-based superconductors without line nodes. Moreover, the resonance enhancement, which can be a measure of the area of sign reversal between the hole and electron Fermi surfaces (FSs), is comparable to those without line nodes. These facts indicate that the sign reversal between the FSs is still dominant in this system, and the line nodes should create only limited area of sign-reversal on a single FS. Hence the system can hold higher Tc than the other iron-based superconductors with nodal symmetry, such as LaFePO
and KFeAs (
10 K).
Aizawa, Kosuke; Chikazawa, Yoshitaka; Usui, Shinichi; Konomura, Mamoru; Ando, Masato*
JAEA-Research 2007-042, 105 Pages, 2007/06
JAEA-Research-2007-042.pdf:3.64MB
Various conceptual design studies of sodium cooled small reactor have been performed in the feasibility study. In FY2005 study, a 300MWe modular reactor which adopts metal-fueled and 1 loop cooling system in order to pursues economical competitiveness was investigated. Transient analyses were performed to show core safety under the large pipe break accident that was found to be the severest accident in case of a 1 loop cooling system. From the analysis results, it was showed a possibility to maintain the core safety without the reactor scram. Transient analyses of the natural circulation decay heat removal system were also performed, and it was showed a possibility to maintain the core safety after the reactor scram. The in-vessel storage (IVS) was adopt to eliminate the ex-vessel storage and the design of the distribution flow adjustment device in IVS is studied. It was showed that the IVS could be introduced without modifying in the reactor design in FY2004. The rationalization of the fuel handling system is investigated taking advantage of co-location plant in which the reactor, the recycle plant and the fuel fabrication plant are co-located in a site. As a result of rationalization, the volume of the reactor building becomes 0.85 times as much as that of the design in FY2004.
Hishida, Masahiko; Murakami, Tsutomu*; Kisohara, Naoyuki; Fujii, Tadashi; Uchita, Masato*; Hayafune, Hiroki; Chikazawa, Yoshitaka; Usui, Shinichi; Ikeda, Hirotsugu; Uno, Osamu; et al.
JAEA-Research 2006-006, 125 Pages, 2006/03
JAEA-Research-2006-006.pdf:11.55MB
In Phase I of the "Feasibility Studies on Commercialized Fast Reactor Cycle Systems (F/S)", an advanced loop type reactor has been selected as a promising concept of sodium-cooled reactor, which has a possibility to fulfill the design requirements of the F/S. In Phase II, design improvement for further cost reduction and the establishment of the plant concept has been performed. In this study, reactor core design and large-scale plant design have been performed by adopting the modified fuel assembly with inner duct structure and double-wall straight tube steam generator (SG), which concepts were chosen at the interim review of FY 2003. For this SG, safety logics have been studied and the structural concept has been established. And the plant designs improving the in-service inspection (ISI) and repair capability have been performed. Furthermore, elaborate confirmation of the design has been performed reflecting the development of elemental technology, back-up concepts have been proposed. Besides, cost reduction measures have been studied by reducing reactor grade materials, introducing autonomous standardizations, simplifying the design due to deregulation and adopting systemized standards for BOP and NSSS. From now on, reflecting the results of elemental experiments, in-depth design studies and examination of critical issues will be carried out and the plant concept will accomplish in preparation for the final evaluation in Phase II.
Matsuoka, Mamoru; Akiba, Masato; Usui, Katsutomi; Ohara, Hiroshi; Ohara, Yoshihiro; Kuriyama, Masaaki; Horiike, Hiroshi
JAERI-M 89-075, 21 Pages, 1989/06
no abstracts in English
Akiba, Masato; Kawai, Mikito; Komata, Masao; Ohara, Hiroshi; Usui, Katsutomi
KEK-R-87-25, p.73 - 73, 1988/00
no abstracts in English
Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; et al.
no journal, ,
Three years have passed since the discovery of iron-based superconductors, its maximum superconducting transition temperature () is 55 K, resulting in second highest material system next to cuprate high- superconductors. Among various material systems in iron-based superconductors, we have systematically studied on LaFeAsO
F
(
=28 K) of first discovered system and BaFe(As,P) which have recently attracted tremendous attention by the discovery of line nodes in its order parameter. In the session, we present recent results on "spin fluctuation and superconductivity on LaFePO
", and "symmetry of order parameter on BaFe(As,P) by inelastic neutron scattering" studied by the chopper spectrometer 4SEASONS (J-PARC).
(As,P)Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.
no journal, ,
In this study, we have performed inelastic neutron scattering measurement on 36g powder sample of optimally-doped BaFe(As,P) whose superconducting order parameter is expected to have line node by Fermi chopper spectrometer 4SEASONS in J-PARC. Unexpectedly, we have observed spin resonance at same 
-position and nearly identical resonance enhancement ration to other iron-based superconducctors with fully-gapped 
-wave. We will discuss about the possible superconducting gap symmetry based on our experimental results.
superconductorsIshikado, Motoyuki; Kodama, Katsuaki; Wakimoto, Shuichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; et al.
no journal, ,
Among various iron-based superconductors, we have systematically studied on LaFeAsOF (=28 K) and BaFe(As,P) (=31 K) by the Fermi chopper spectrometer 4SEASONS (J-PARC). We will discuss the possible relation between high- superconductivity and magnetic fluctuation based on our inelastic neutron scattering results.
(As,P) with nodal gap symmetryIshikado, Motoyuki; Kodama, Katsuaki; Wakimoto, Shuichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.
no journal, ,
In this study, we performed inelastic neutron scattering measurement on 36g polycrystalline powder sample of optimally-doped BaFe(AsP) using a Fermi chopper spectrometer 4SEASONS in J-PARC. We observed strong spin resonance at the same -position similar to those of other iron-based superconductors with fully-gapped -wave. We will discuss about the possible superconducting gap symmetry and what causes relatively high-
of this material based on our inelastic neutron scattering results.
(As,P)Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; et al.
no journal, ,
We report systematic studies on Fe-based superconductors LaFeAsOF (
=28 K) and BaFe(As,P) ( =31 K) by using inelastic neutron scattering measurement.
(As,P) with =30KIshikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.
no journal, ,
In this study, we performed inelastic neutron scattering measurement on 36g polycrystalline powder sample of optimally-doped BaFe(As,P) using Fermi chopper spectrometer 4SEASONS in J-PARC. Unexpectedly, we observed spin resonance at the same -position and nearly identical resonance enhancement ratio to other iron-based superconductors with fully-gapped -wave. We will discuss about the possible superconducting gap symmetry based on our inelastic neutron scattering experiment and theoretical calculations.
Ishikado, Motoyuki; Kodama, Katsuaki; Wakimoto, Shuichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; et al.
no journal, ,
We have systematically studied nodal iron-based superconductor LaFePO (=5 K) and BaFe(As,P) (=30 K) by using Fermi chopper spectrometer 4SEASONS (J-PARC) and Triple Axis Spectrometer (TAS-1) at JRR-3. In the session, we will discuss the relation between superconductivity and spin fluctuation.
Murata, Masato; Katano, Yoshiaki; Usui, Hideo; Kubota, Shintaro
no journal, ,
As of October 2014, four Nuclear Power Plants, such as Tokai-1, Hamaoka Power Station Unit 1, Unit 2 and Fugen, have been carried out decommissioning, and JAEA's facilities, such as JRR-2, JRTF, RHL, PFFF, have been decommissioned, too. This presentation shows the decommissioning strategy and current status of decommissioning in Japan at ANUP2014.
