Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nakagawa, Akinori; Sasaki, Toshiki; Sakamoto, Yoshiaki
Radioactive Waste Management; Solutions for a Sustainable Future (Supplement) (Internet), 7 Pages, 2023/00
Japan Atomic Energy Agency (JAEA) has stored radioactive wastes generated from R&D activities related to nuclear science and technology. A part of these wastes contains compressed wastes without prior radiological, chemical or physical characterization assessed, as well as mixed wastes containing lead and mercury with little information about its contents. Pre-treatment and radiological characterization efforts for such problematic wastes are very time consuming and costly. In order to optimize the processing and disposal of the problematic wastes, a method to balance the processing work and disposal facility robustness was studied. Work analysis of waste processing showed bottleneck processes, such as radiological characterization and segregation of hazardous materials and combustibles. Establishment of a conservative scaling factor method and non-destructive gamma-ray measurement enable easier radiological characterization. Hazardous materials will be identified using records and nondestructive inspection. The waste identified as hazardous will be unpacked and segregated. Based on preliminary survey of about 1,000 drums, only 10 % of stored drums contain hazardous materials and need segregation. Regarding the separation of combustibles, total volume of the combustibles will be evaluated using nondestructive inspection technique such as high-energy X-ray CT and the waste that does not comply with the waste acceptance criteria should be mixed with waste containing a small amount of combustibles in order to satisfy the waste acceptance criteria on a disposal facility average. It was estimated that segregation throughput of compressed waste should be increased about 5 times more than conventional method by applying the countermeasures.
Nakagawa, Akinori; Oyokawa, Atsushi; Murakami, Masashi; Yoshida, Yukihiko; Sasaki, Toshiki; Okada, Shota; Nakata, Hisakazu; Sugaya, Toshikatsu; Sakai, Akihiro; Sakamoto, Yoshiaki
JAEA-Technology 2021-006, 186 Pages, 2021/06
JAEA-Technology-2021-006.pdf:54.45MB
Radioactive wastes generated from R&D activities have been stored in Japan Atomic Energy Agency. In order to reduce the risk of taking long time to process legacy wastes, countermeasures for acceleration of waste processing and disposal were studied. Work analysis of waste processing showed bottleneck processes, such as evaluation of radioactivity concentration, segregation of hazardous and combustibles materials. Concerning evaluation of radioactivity concentration, a radiological characterization method using a scaling factor and a nondestructive gamma-ray measurement should be developed. The number of radionuclides that are to be selected for the safety assessment of the trench type disposal facility can decrease using artificial barriers. Hazardous materials, will be identified using records and nondestructive inspection. The waste identified as hazardous will be unpacked and segregated. Preliminary calculations of waste acceptance criteria of hazardous material concentrations were conducted based on environmental standards in groundwater. The total volume of the combustibles will be evaluated using nondestructive inspection. The waste that does not comply with the waste acceptance criteria should be mixed with low combustible material waste such as dismantling concrete waste in order to satisfy the waste acceptance criteria on a disposal facility average. It was estimated that segregation throughput of compressed waste should be increased about 5 times more than conventional method by applying the countermeasures. Further study and technology development will be conducted to realize the plan.
Sugaya, Toshikatsu; Nakatani, Takayoshi; Sasaki, Toshihisa*; Nakamura, Yasuo*; Sakai, Akihiro; Sakamoto, Yoshiaki
JAEA-Technology 2016-036, 126 Pages, 2017/02
JAEA-Technology-2016-036.pdf:7.28MB
At the Radioactive Waste Management and Disposal Project Department Sector of Decommissioning and Radioactive Waste Management, we performed the technological study about the disposal measures of the low-level radioactive waste targeted for uranium-bearing waste and intermediate depth disposal-based waste occurring from the process of the nuclear fuel cycle.
Onoda, Shinobu; Hasuike, Atsushi*; Nabeshima, Yoshiaki*; Sasaki, Hajime*; Yajima, Kotaro*; Sato, Shinichiro; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 60(6), p.4446 - 4450, 2013/12
Times Cited Count：43 Percentile：94.67(Engineering, Electrical & Electronic)no abstracts in English
Abe, Sadayoshi; Kuwae, Yoshiaki*; Sasaki, Satoru*; Takahashi, Kazutoshi*
Genshiryoku, hoshasen Bukaiho (Internet), (10), p.6 - 8, 2012/03
Between January 30, 2012 August 26, 2011, the support for the correct understanding of nuclear and radiation due to comments and advice to participate in disaster reconstruction committee formulated vision of the Tomioka town, as a professional Engineers, Japan was carried out, As a result, the vision I hope to go back to town Tomioka are taken together to form all townspeople have been developed.
Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.
JAEA-Technology 2011-031, 123 Pages, 2012/01
JAEA-Technology-2011-031.pdf:16.08MB
The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.
Sasaki, Yasuo; Torata, Shinichiro; Numata, Yoshiaki
JAEA-Review 2008-078, 51 Pages, 2009/03
JAEA-Review-2008-078.pdf:5.57MB
JAEA organizes the "Technical Committee for Geological Isolation Research & Development", which consists of specialists in relevant fields at universities and institutes, in order to facilitate planning and conducting of a program of research and development (R&D) for geological disposal of high-level radioactive waste and TRU waste at JAEA-Tokai, through reflecting technical advices and comments made from them into the program. This report presents the minutes of the third meeting held in March 2008.
Sasaki, Yasuo; Numata, Yoshiaki; Torata, Shinichiro
JAEA-Review 2008-068, 23 Pages, 2009/02
JAEA-Review-2008-068.pdf:2.73MB
The nuclear waste disposal is still in discussion as one of the key issue while we continue the sustainable atomic energy use, and it has been taking with much of the viewpoint of the social acceptance. In addition it may be said that it is the problem that the long term necessity to promote the disposal arise the subjects of the security of people who take charge of the disposal project. Also the management of knowledge with technical information between generations would become another subject in the future. To find the way out of these concerns, the practices having been tryed by the researcher group towards the student generation are reviewed in this report. The results of the opinion exchange and scientific communication with the people in the educational institution by the disposal research scientists are reviewed based on the questionnaire and discussion at a practice of schooling and lecture at high schools and universities.
Sasaki, Yasuo; Torata, Shinichiro; Numata, Yoshiaki
JAEA-Review 2008-016, 69 Pages, 2008/03
JAEA-Review-2008-016.pdf:7.79MB
In order to plan and conduct a program of research and development (R&D) for geological disposal of high-level radioactive waste in JAEA-Tokai, JAEA decided to receive technical comments and advices from the Technical Committee for geological isolation R&D. This committee, which is constituted of specialists who do not belong to JAEA, has evaluated the program, taking into account of the status of geological disposal technology in Japan as well as foreign countries. This report compiles the minutes of the second meeting held in March 2007.
Hasegawa, Noboru; Kawachi, Tetsuya; Sasaki, Akira; Kishimoto, Maki; Sukegawa, Kota; Tanaka, Momoko; Tai, R. Z.*; Ochi, Yoshihiro; Nishikino, Masaharu; Nagashima, Keisuke; et al.
Physical Review A, 76(4), p.043805_1 - 043805_5, 2007/10
Times Cited Count：20 Percentile：66.81(Optics)We firstly demonstrated the measurement of temporal profile of the amplification gain of the transient collisional excitation (TCE) X-ray laser with the solid target by use of X-ray diagnostic beam injection technique. In this experiment, higher-order harmonic light at a wavelength of 26.9 nm was injected into the neon-like manganese plasma as X-ray laser medium, and the amplified signal was observed. The obtained buildup time of the amplification gain was 23 ps measured from the time of the main pumping laser pulse, and the lifetime of the amplification gain was 27 ps. This result was in good agreement with the theoretical simulation by using an atomic kinetics code.
Ochi, Yoshihiro; Kawachi, Tetsuya; Sasaki, Akira; Nagashima, Keisuke; Hasegawa, Noboru; Tanaka, Momoko; Kishimoto, Maki; Nishikino, Masaharu; Kato, Yoshiaki
X-Ray Lasers 2004; Institute of Physics Conference Series, Vol.186, p.111 - 114, 2005/06
We have measured the temporal duration of the TCE X-ray laser (XRL) with Ni-like silver (Ag; Z = 47), palladium (Pd; Z = 46), and molybdenum (Mo; Z = 42). The pumping pulse was derived from Nd:glass laser system with the chirped pulse amplification at the wavelength of 1053 nm. The duration of the main pulse and prepulse were set to be 4.8 ps and 400 ps respectively. The pulse separation between the pulses was typically 500 ps. A quasi-traveling wave pumping using 6-step mirror was adopted in the focusing system. The X-ray laser outputs were measured by use of an X-ray streak camera coupled with a flat field spectrometer. The observed durations were 9.3 ps, 6.2 ps, and 3.9 ps for Ag, Pd, and Mo XRLs respectively, resulting in the longer duration for the higher atomic number material. We will discuss the gain generation in the plasma medium with the help of numerical simulation and atomic code.
Hasegawa, Noboru; Kawachi, Tetsuya; Utsumi, Takayuki*; Sasaki, Akira; Tanaka, Momoko; Kado, Masataka; Sukegawa, Kota*; Lu, P.; Kishimoto, Maki; Tai, R.; et al.
Japanese Journal of Applied Physics, Part 1, 43(5A), p.2519 - 2522, 2004/05
Times Cited Count：12 Percentile：45.03(Physics, Applied)We conducted high-precision measurements of the wavelength of the nickel-like silver X-ray laser in order to compare it with a theoretical wavelength. The reasons for using this laser are as follows: First, this laser line is in the wavelength region of Mo/Si multi-layer mirrors; therefore, this laser line is important for applications. Second, the strongamplification of this laser line has been obtained in our previous work, and the higher order line in the spectra obtained by our spectrometer can be used. Third, since silver is arelatively low-z material (z = 47), this wavelength is a ideal benchmark of atomic structural codes such as the Multiconfiguration Dirac-Fock (MCDF) code. The wavelength of the nickel-like silver X-ray laser was determined to be 13.887 nm. The comparison with MCDF codes shows that the present experimental result can work as a good benchmark of the accuracy of the codes.
Kawachi, Tetsuya; Sasaki, Akira; Tanaka, Momoko; Kishimoto, Maki; Hasegawa, Noboru; Nagashima, Keisuke; Koike, Masato; Daido, Hiroyuki; Kato, Yoshiaki
Physical Review A, 69(3), p.033805_1 - 033805_4, 2004/03
Times Cited Count：16 Percentile：57.77(Optics)We have observed strong amplification for the 4d-4p transition of the Ni-like La ions at a wavelength of 8.8nm pumped by a chirped pulse amplificatio Nd:glass laser with an energy of 18 J. In this experiment, laser pulses consist of a pre-pulse and a main pulse with duration of 200ps and 7 ps separated by 250ps. The KeV X-ray spectroscopy and theoretical calculation indicate that the plasma temperature increasesd effectively by reducing the prepulse intensity, and that the substantial gain is generated in a small overcritical region heated by the electron heat transport.
Oku, Takayuki*; Sakai, Kenji*; Adachi, Tomohiro*; Ikeda, Kazuaki*; Shimizu, Hirohiko*; Maruyama, Ryuji*; Hino, Masahiro*; Tasaki, Seiji*; Kiyanagi, Yoshiaki*; Kamiyama, Takashi*; et al.
Physica B; Condensed Matter, 335(1-4), p.226 - 229, 2003/07
Times Cited Count：7 Percentile：39.31(Physics, Condensed Matter)no abstracts in English
Sakamoto, Yoshiaki; Ishii, Tomoaki*; Inagawa, Satoshi*; Gunji, Yasuyoshi*; Takebe, Shinichi; Ogawa, Hiromichi; Sasaki, Tomozo*
Journal of Nuclear Science and Technology, 39(Suppl.3), p.481 - 484, 2002/11
Sorption behavior of 227Ac and 233Pa onto several kinds of soils has been studied with a sequential extraction technique, for safety assessment of shallow land disposal of uranium bearing waste. After a batch sorption experiment, the sorbed form of 227Ac and 233Pa onto the soils was fractionated into ion exchange form (extraction by KCl+CaCl2), association with Fe+Mn oxides (extraction by NH2OH-HCl and oxalic acid), association with organic materials (extraction by H2O2) and fixation into soil (residual). From the results of the sequential extraction, major part of 227Ac sorbed onto the soils was found in the fraction of the ion exchange form and the fixation into the soils. On the other hand, major part of 233Pa was found in the fraction of the association with Fe+Mn oxides and the fixation into the soils. These results suggest that the sorption behavior of 227Ac and 233Pa is related to the irreversible sorption reaction onto the soils.
Kawachi, Tetsuya; Kado, Masataka; Tanaka, Momoko; Sasaki, Akira; Hasegawa, Noboru; Kilpio, A.*; Namba, Shinichi; Nagashima, Keisuke; Lu, P.; Takahashi, Kenjiro; et al.
Physical Review A, 66(3), p.033815_1 - 033815_7, 2002/09
Times Cited Count：85 Percentile：93.02(Optics)A silver and tin slab targets were irradiated by a line-focused CPA glass laser light. In this experiment, the laser pulses consisted of two pulses with 4 ps duration, separated by 1.2 ns. Strong amplification in the nickel-like silver and tin x-ray lasers at the wavelengths of 13.9nm and 12.0nm was demonstrated with a pumping energy of 12 J and 14 J, respectively, and gain-saturation behaviors could be seen. A hydro-dynamics simulation coupled with a collisional-radiative model was performed under the present experimental condition, and the calculated result was compared with the experimental results.
Kato, Yoshiaki; Daido, Hiroyuki; Nagashima, Keisuke; Kawachi, Tetsuya; Hasegawa, Noboru; Tanaka, Momoko; Tang, H.; Tai, R.; Lu, P.; Kishimoto, Maki; et al.
AIP Conference Proceedings 641, p.31 - 39, 2002/00
no abstracts in English
Kado, Masataka; Kawachi, Tetsuya; Tanaka, Momoko; Hasegawa, Noboru; Takahashi, Kenjiro; Namba, Shinichi; Sukegawa, Kota*; Sasaki, Akira; Lu, P.; Tang, H.; et al.
Soft X-Ray Lasers and Applications IV (Proceedings of SPIE Vol.4505), p.54 - 61, 2001/12
Times Cited Count：4 Percentile：79.44(Optics)no abstracts in English
Sakamoto, Yoshiaki; Ishii, Tomoaki*; Inagawa, Satoshi*; Gunji, Yasuyoshi*; Takebe, Shinichi; Ogawa, Hiromichi; Sasaki, Tomozo*
Genshiryoku Bakkuendo Kenkyu, 8(1), p.65 - 76, 2001/09
In order to study adsorption behavior of U series radionuclides(Pb, Ra, Th, Ac, Pa and U) in aerated zone environment (loam-rein water system) and aquifer environment(sand-groundwater system) for safety assessment of U bearing waste), pH dependence of distribution coefficients of each element have been obtained. The pH dependence of distribution coefficients of U, Ac, Th, Ra and Pb was analyzed by model calculation of adsorption behavior based on chemical forms of each elements and soil surface characteristics, which are a cation exchange capacity and surface charge. From model calculation of adsorption behavior, the distribution coefficients' values and adsorption behavior of Pb, Ra, Th, Ac and U could be showed by a combination of cation exchange and surface-complexation adsorption model.
Ishii, Tomoaki*; Inagawa, Satoshi*; Gunji, Yasuyoshi*; Sakamoto, Yoshiaki; Takebe, Shinichi; Ogawa, Hiromichi; Sasaki, Tomozo*
Genshiryoku Bakkuendo Kenkyu, 8(1), p.55 - 64, 2001/09
Distribution coefficients of Uranium series nuclide(Pb,Ra,Ac,Th,Pa and U) were obtained under aerated zone environment and aquifer environment, for the safety evaluation of shallow underground disposal of uranium bearing waste. The distribution coefficients of them on 4 kinds of soil such as the loam in the rain water as for aerated zone environment and on 3 kinds of soil and rock such as the sand in groundwater as for aquifer environment have been measured by batch method. The distribution coefficients in aerated zone environment were one or two orders in magnitude higher than that in aquifer environment, except Ac. And, there was approximately the linear correlation on the relationship between cation exchange capacity and specific surface area, which are representative physical property of the soil, and distribution coefficient of lead, radium and protactinium.
