Yonomoto, Taisuke; Nakashima, Hiroshi*; Sono, Hiroki; Kishimoto, Katsumi; Izawa, Kazuhiko; Kinase, Masami; Osa, Akihiko; Ogawa, Kazuhiko; Horiguchi, Hironori; Inoi, Hiroyuki; et al.
JAEA-Review 2020-056, 51 Pages, 2021/03
A group named as "The group for investigation of reasonable safety assurance based on graded approach", which consists of about 10 staffs from Sector of Nuclear Science Research, Safety and Nuclear Security Administration Department, departments for management of nuclear facility, Sector of Nuclear Safety Research and Emergency Preparedness, aims to realize effective graded approach (GA) about management of facilities and regulatory compliance of JAEA. The group started its activities in September, 2019 and has had discussions through 10 meetings and email communications. In the meetings, basic ideas of GA, status of compliance with new regulatory standards at each facility, new inspection system, etc were discussed, while individual investigation at each facility were shared among the members. This report is compiled with expectation that it will help promote rational and effective safety management based on GA by sharing contents of the activity widely inside and outside JAEA.
Nagai, Takayuki; Kobayashi, Hidekazu; Sasage, Kenichi; Ayame, Yasuo; Okamoto, Yoshihiro; Shiwaku, Hideaki; Matsuura, Haruaki*; Uchiyama, Takafumi*; Okada, Yukiko*; Nezu, Atsushi*; et al.
JAEA-Research 2016-015, 52 Pages, 2016/11
The local structure of waste elements in simulated waste glasses including V was estimated by using synchrotron XAFS measurement in this study. The results are as follows. (1) V has a high possibility which exists in the glass phase in the case of frit, and V can regard both samples as stable 4 coordination structure. (2) Zn, Ce, Nd, Zr, and Mo exist in the glass phase, and the difference is admitted by the percentage of Ce(III) and Ce(IV) by the composition. (3) Ru is separated from the glass phase as RuO crystalline, both of metal and oxide exist in Rh, and Pd is separated out as metal. (4) It was confirmed that the regularity of the local structure of Zr and Mo in the molten glasses retreats as a result of the XAFS measurement at high temperature. (5) The XAFS measurement of molten glasses were performed at 1200C, so it would be possible to acquire excellent data by improving the shapes of the sample cell.
Shibata, Akira; Ito, Masayasu; Takemoto, Noriyuki; Nakatsuka, Masafumi*; Ohara, Hiroshi*; Kodama, Mitsuhiro*; Tanimoto, Masataka; Tsuchiya, Kunihiko
JAEA-Technology 2011-034, 67 Pages, 2012/02
Reflector elements made from metal beryllium is widely used as neutron reflectors to increase neutron flux in test reactors. When beryllium reflector elements are irradiated by neutron, bending of reflector elements caused by swelling occurs, and beryllium reflector elements must be replaced in several years. In this report, investigation for non-destructive inspection method of metal Beryllium and experiments for Preliminary inspection to establish post irradiation examination method for research of characteristics of metal beryllium under neutron irradiation were reported.
Numakura, Masahiko*; Sato, Nobuaki*; Bessada, C.*; Okamoto, Yoshihiro; Akatsuka, Hiroshi*; Nezu, Atsushi*; Shimohara, Yasuaki*; Tajima, Keisuke*; Kawano, Hirokazu*; Nakahagi, Takeshi*; et al.
Progress in Nuclear Energy, 53(7), p.994 - 998, 2011/11
X-ray absorption fine structure (XAFS) measurements on thorium fluoride in molten lithium-calcium fluoride mixtures and molecular dynamics (MD) simulation of zirconium and yttrium fluoride in molten lithium-calcium fluoride mixtures have been carried out. In the molten state, coordination number of thorium and inter ionic distances between thorium and fluorine in the first neighbor are nearly constant in all mixtures. However the fluctuation factors (Debye-Waller factor and C cumulant) increase until CaF = 0.17 and decrease by addition of excess CaF. It means that the local structure around Th is disordered until CaF=0.17 and stabilized over CaF = 0.17. The variation of fluctuation factors is related to the number density of F in ThF mixtures and the stability of local structure around Th increases with decreasing the number density of F in ThF mixtures. This tendency is common to those in the ZrF and YF mixtures.
Ozawa, Masaki; Suzuki, Tatsuya*; Koyama, Shinichi; Akatsuka, Hiroshi*; Mimura, Hitoshi*; Fujii, Yasuhiko*
Progress in Nuclear Energy, 50(2-6), p.476 - 482, 2008/03
For the minimization of the ecological burden originated in nuclear fuel recycling, a new R&D strategy was filed as "Adv.-ORIENT cycle". In the context, mutual precise separation of -elements, such as minor actinide (MA)/lanthanides (Lns) and Am/Cm, are highly essential for enhancing the MA (Am) burning. The separation and utilization of rare metal fission products (RMFPs; Ru, Tc, etc) are a new direction in the partitioning and transmutation field. Separation of exothermic nuclides, Sr, Cs as well as MA, will significantly help to improve the repository tasks. A key separation media are ion exchange chromatography (IXC) by tertiary pyridine resin and a catalytic electrolytic extraction (CEE) by Pd. On challenging the isotope separation of LLFP, theoretical and laboratory studies were begun for Cs, Sn in the first priority.
Oshita, Hironori; Ozawa, Masaki; Ishikawa, Makoto; Koyama, Shinichi; Akatsuka, Hiroshi*
JAEA-Review 2007-031, 41 Pages, 2007/09
Recently establishment of self consistent nuclear fuel cycle has been required with respect to economical efficiency, safety and reduction of the load to the environment. Especially Cs included in spent fuel of nuclear power plants has extremely long half life (3.010y) and its water solubility leads to the anxiety of exudation into ground water in geologic disposal. Recent technology development of laser has come to make it possible in principle to excite a specific isotope and separate it making use of the intrinsic physical and chemical properties of the excited state. This document reports the review of the isotope separation principle and its application to Cs separation.
Iwamura, Takamichi; Uchikawa, Sadao; Okubo, Tsutomu; Kugo, Teruhiko; Akie, Hiroshi; Nakano, Yoshihiro; Nakatsuka, Toru
Nuclear Engineering and Design, 236(14-16), p.1599 - 1605, 2006/08
In order to ensure sustainable energy supply in the future based on the matured Light Water Reactor (LWR) and coming Mixed Oxide (MOX)-LWR technologies, a concept of Innovative Water Reactor for Flexible Fuel Cycle (FLWR) has been investigated in Japan Atomic Energy Research Agency (JAEA). The concept consists of two parts in the chronological sequence. The first part realizes a high conversion type core concept, which is basically intended to keep the smooth technical continuity from current LWR and coming MOX-LWR technologies without significant technical gaps. The second part represents the Reduced-Moderation Water Reactor (RMWR) core concept, which realizes a high conversion ratio over 1.0 being useful for the long-term sustainable energy supply through plutonium multiple recycling based on the well-developed LWR technologies. The key point is that the two core concepts utilize the compatible and the same size fuel assemblies, and hence, the former concept can proceed to the latter in the same reactor system, based flexibly on the future fuel cycle circumstances during the reactor operation period around 60 years. Investigation on the core for both the parts of the FLWR concepts has been performed, including the core conceptual design, the core characteristics under Pu multiple recycling, the thermal hydraulic investigation in the tight-lattice core, and so forth. Up to the present, promising results have been obtained.
Iwamura, Takamichi; Uchikawa, Sadao; Okubo, Tsutomu; Kugo, Teruhiko; Akie, Hiroshi; Nakatsuka, Toru
Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), 8 Pages, 2005/05
In order to ensure sustainable energy supply in the future based on the matured Light Water Reactor (LWR) and coming LWR-Mixed Oxide (MOX) technologies, a concept of Innovative Water Reactor for Flexible Fuel Cycle (FLWR) has been investigated in Japan Atomic Energy Research Institute (JAERI). The concept consists of two parts in the chronological sequence. The first part realizes a high conversion type core concept, which is basically intended to keep the smooth technical continuity from current LWR without significant gaps in technical point of view. The second part represents the Reduced-Moderation Water Reactor (RMWR) core concept, which realizes a high conversion ratio over 1.0 being useful for the long-term sustainable energy supply through plutonium multiple recycling based on the well-experienced LWR technologies. The key point is that the two core concepts utilize the compatible and the same size fuel assemblies, and hence, the former concept can proceed to the latter in the same reactor system, based flexibly on the fuel cycle circumstances.
Hanamuro, Takahiro; Saito, Hiroshi; Asamori, Koichi; Iyatomi, Yosuke; Tsuruta, Tadahiko; Yabuuchi, Satoshi; Mizuno, Takashi; Sato, Toshinori; Nakatsuka, Noboru; Shigeta, Naotaka; et al.
JNC TN7400 2004-010, 173 Pages, 2004/12
Japan Nuclear Cycle Development Institute. (JNC) is developing two underground research laboratory projects; the Mizunami Underground Research Laboratory(MIU) Project for crystalline rock,.at Tono Geoscience Center (TGC) and the Horonobe Underground Research Laboratory ・Project for・ sedimentary rock at the Horonobe Underground Research Center. Both projects are intended for research and development of geological disposal technology for high-level radioactive wastes. At this time, these two underground research laboratory projects are advancing to the Construction Phase (Phase II) from the Surface-based Investigation Phase (Phase I). Therefore it was considered appropriate for JNC to hold an international conference to introduce the two underground research laboratory projects and R&D results from Phase I, to have presentations on overseas URLs, to exchange opinions by researchers in each field of research and to reflect the conference outcome in a future R&D plan. The Conference was held in two parts. Part 1, the "International Conference on Geoscientific Study in Mizunami '04 (ICGM '04)" featured the MIU Project and the Regional Hydrogeological Study Project performed by TGC. It was held in Mizunami City at the Sogo Bunka Center from October 21st to 22nd. In Part 2, the "International Workshop on Horonobe Underground Research Laboratory Project", featured the Horonobe Underground Research Laboratory Project performed by the Horonobe Underground Research Center. It was held at Horonobe Town Hall from, October 25th to 26th 2004. This Technical Report documents the ICGM'04 program, abstracts of presentations and slides and transcription of "Panel Discussions II and "Summary of the Conference"
Iwamura, Takamichi; Okubo, Tsutomu; Akie, Hiroshi; Kugo, Teruhiko; Yonomoto, Taisuke; Kureta, Masatoshi; Ishikawa, Nobuyuki; Nagaya, Yasunobu; Araya, Fumimasa; Okajima, Shigeaki; et al.
JAERI-Research 2004-008, 383 Pages, 2004/06
The present report contains the achievement of "Research and Development on Reduced-Moderation Light Water Reactor with Passive Safety Features", which was performed by Japan Atomic Energy Research Institute (JAERI), Hitachi Ltd., Japan Atomic Power Company and Tokyo Institute of Technology in FY2000-2002 as the innovative and viable nuclear energy technology (IVNET) development project operated by the Institute of Applied Energy (IAE). In the present project, the reduced-moderation water reactor (RMWR) has been developed to ensure sustainable energy supply and to solve the recent problems of nuclear power and nuclear fuel cycle, such as economical competitiveness, effective use of plutonium and reduction of spent fuel storage. The RMWR can attain the favorable characteristics such as high burnup, long operation cycle, multiple recycling of plutonium (Pu) and effective utilization of uranium resources based on accumulated LWR technologies.
Suzuki, Masaaki*; Sekiguchi, Hidetoshi*; Akatsuka, Hiroshi*; Goto, Takanobu*; Osugi, Takeshi*; Kobayashi, Hiroaki; Nakazawa, Osamu
JNC TY8400 2002-016, 158 Pages, 2002/03
*; Akatsuka, Hiroshi*; *; Suzuki, Tatsuya*; *; *;
JNC TY9400 2000-009, 41 Pages, 2000/03
no abstracts in English
Iwamura, Takamichi; Okubo, Tsutomu; Shimada, Shoichiro*; Usui, Shuji*; Shirakawa, Toshihisa*; Nakatsuka, Toru; Kugo, Teruhiko; Akie, Hiroshi; Nakano, Yoshihiro; Wada, Shigeyuki*
JAERI-Research 99-058, p.61 - 0, 1999/11
no abstracts in English
Hatae, Takaki; Narihara, Kazumichi*; Yamada, Ichihiro*; Yoshida, Hidetsugu*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Minami, Takashi*; Funaba, Hisamichi*; Kajita, Shin*; Kitamura, Shigeru; et al.
no journal, ,
no abstracts in English
Numakura, Masahiko*; Bessada, C.*; Ory, S.*; Rakhamatullin, A.*; Akatsuka, Hiroshi*; Nezu, Atsushi*; Yaita, Tsuyoshi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Matsuura, Haruaki*
no journal, ,
To investigate the local structure of molten TbF - LiF (x[TbF = 0.2), X-ray absorption fine structure technique (XAFS) was applied using by BL11XU in SPring-8. By several analyses, e.g. X-ray diffraction and differential scanning calorimetry, it had been confirmed that TbF and boron nitride reacted at less than 1073 K even under helium gas flow environment, thus, we focused on the spectrum obtained below 1073 K. According to the curve fitting, the interionic distance obtained from the data of heating between 933 K and 1013 K was shorter than solid state. It would be surely molten state of TbF - LiF (x[TbF] = 0.2), since the value of distance obtained, i.e. 2.26 corresponds to the sum of ionic radii of Tb and F.
Hatae, Takaki; Yamada, Ichihiro*; Yoshida, Hidetsugu*; Narihara, Kazumichi*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Funaba, Hisamichi*; Minami, Takashi*; Kajita, Shin*; Tojo, Hiroshi; et al.
no journal, ,
no abstracts in English
Hatae, Takaki; Kitamura, Shigeru; Sakuma, Takeshi; Hamano, Takashi; Tojo, Hiroshi; Yoshida, Hidetsugu*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Narihara, Kazumichi*; Yamada, Ichihiro*; et al.
no journal, ,
Hatae, Takaki; Yatsuka, Eiichi; Yoshida, Hidetsugu*; Fujita, Hisanori*; Tsubakimoto, Koji*; Nakatsuka, Masahiro*; Yasuhara, Ryo*; Tojo, Hiroshi; Sakuma, Takeshi
no journal, ,
no abstracts in English