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Suzuki, Kenji*; Miura, Yasufumi*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Shobu, Takahisa; Morooka, Satoshi
Zairyo, 72(4), p.316 - 323, 2023/04
Tetsu, Keiichi*; Takayama, Yusuke; Sawada, Atsushi
JAEA-Research 2022-005, 84 Pages, 2022/08
Nuclide migration analyses are conducted for the safety assessment in geological disposal system of HLW. Nuclide migration evaluation of fractured host rock mainly uses a model that approximates the fracture with parallel flat plates. However, the actual fractures in the host rock are different from the parallel flat plates, the fractures have complex characteristics such as roughness of fracture surface and the fillings in the fracture. In approximating a fracture model, the methodology development how to set parameter values such as the transmissivity coefficient and the fracture aperture is an issue. One of the issues is to investigate the geometrical features of actual fractures in the host rock. In this study, for the purpose of understanding the geometrical features of fractures including fracture intersection, the internal fracture shape was measured in detail using the method of surface grinding on 50cm scale granodiorite with natural fracture intersection. Thus, the fracture width, fracture aperture, and the shape of the fracture surfaces were obtained. From the obtain data, characteristics such as the average value of the fracture width, the roughness of the fracture surfaces, and the distribution of the fracture aperture were evaluated. As a result, it was confirmed that one of the fractures near the fracture intersection has a particularly large fracture width and fracture aperture as compared with the other part of fractures. Thus, in the granodiorite rock block used in this study, it was inferred that the most permeable path is not the fracture intersection itself, but the particularly large fracture aperture in the vicinity of the fracture intersection.
Kato, Atsushi; Kubo, Shigenobu; Chikazawa, Yoshitaka; Miyagawa, Takayuki*; Uchita, Masato*; Suzuno, Tetsuji*; Endo, Junji*; Kubo, Koji*; Murakami, Hisatomo*; Uzawa, Masayuki*; et al.
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 11 Pages, 2022/04
The authors are carrying out conceptual design studies for a pool-type sodium-cooled fast reactor. There are main challenges such as measures against severe earthquake in Japan, thermal hydraulic in a reactor vessel (RV), a decay heat removal system design. When the JP-pool SFR of 650 MWe is installed in Japan, it shall be designed against the severe seismic conditions. Additionally, a newly three-dimensional seismic isolation system is under development.
Sasaki, Yuji
Bunri Gijutsu, 52(2), p.103 - 107, 2022/03
We develop all-inclusive partitioning method for actinides and fission products in high-level radioactive waste. This process is based on the sequential solvent extraction. In order to recover Cs and Sr for the management by interim storage, crown ether compounds are employed. For the removal of Pd and Mo due to production of a stable vitrified object, methylimino-dioctylacetamide (MIDOA) is taken as an extractant. DGA can extract both actinides and trivalent lanthanides. In order to separate each other, dietylenetriamine-triacetic-diamide (DTBA) for the stripping reagent of MA. For the mutual separation of Am/Cm, DGA and DOODA extraction system is taken into consideration.
Collaborative Laboratories for Advanced Decommissioning Science; National Institute of Technology, Kisarazu College*
JAEA-Review 2021-043, 135 Pages, 2022/01
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of dosimetry device in reactor cores under severe radiation environment" conducted from FY2018 to FY2020. Since the final year of this proposal was FY2020, the results for three fiscal years were summarized. Since the radiation level in the reactors and buildings of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (1F) is extremely high due to the accident, it is required to develop radiation measurement technology based on the needs at the 1F working site. In this study, we will develop technologies towards practical application of revolutionary radiation measurement system based on the dose measurement technology utilizing solar cell devices.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Separation Science and Technology, 57(16), p.2543 - 2553, 2022/00
Times Cited Count:4 Percentile:29.12(Chemistry, Multidisciplinary)The mutual separation of actinides (An) from lanthanides (Ln) using the masking agent of DTPA (diethylenetriamine-pentaacetic acid) or DTBA (diethylenetriamine-triacetic acid-bis(diethylacetamide)) in the aqueous phase through DGA extraction, referring TALSPEAK method, is focused. We investigate to obtain the same separation performance using commercially available DTPA on that using DTBA. In this work, we select lactic acid (LA) of pH buffer from 10 organic acids and ethylenediamine (ED) for the pH adjustment. Almost the same D and SF values are obtained among the conditions: TODGA-DTPA-LA-NaOH, TODGA-DTPA-LA-ED, and TODGA-DTBA-LA. The experimental results using batchwise multi-stage extractions show the average yields of Ln (La to Gd) and Am to be 3.73 and 98.1% in the aqueous phase using DGA-DTPA-LA-ED, to be 3.1 and 97.0% using DGA-DTPA-LA-NaOH, and to be 1.61 and 98.7% using DGA-DTBA-LA.
Sasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Solvent Extraction and Ion Exchange, 40(6), p.620 - 640, 2022/00
Times Cited Count:2 Percentile:13.50(Chemistry, Multidisciplinary)Owing to the chemical behavior of trivalent lanthanide and actinide ions with similar ionic radii, realizing this separation is still challenging. All lanthanides, Am, and Cm can be extracted using diglycolamide (DGA), and relatively high An/Ln separation efficiencies have been obtained using diethylenetriamine-triacetic-bisamide (DTBA). To improve the previous results as well as the separation conditions, we used organic acids for pH adjustment. The advantages of this modification included low HNO, DTBA concentrations and pH stability owing to the addition of lactic acid. Under these modified conditions, the recovery rates observed were as follows: 97.1% for Nd with the co-existence of 1.59% Am in organic phase, and 98.4% for Am with the co-existence of 2.95% Nd in aqueous phase.
Collaborative Laboratories for Advanced Decommissioning Science; National Institute of Technology, Kisarazu College*
JAEA-Review 2020-051, 97 Pages, 2021/02
JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Dosimeter for Severe Radiation Environment near Reactor Pressure Vessel" conducted in FY2019.
Wang, G.-J.*; Meng, L.*; Xiao, L.-Y.*; Oka, Makoto; Zhu, S.-L.*
European Physical Journal C, 81(2), p.188_1 - 188_12, 2021/02
Times Cited Count:39 Percentile:90.93(Physics, Particles & Fields)The mass spectrum and strong decays of the S-wave states are studied in the compact tetraquark scenario with the quark model. The model consists of the Coulomb, the linear confinement, and the hyperfine interactions. We calculate their decay amplitudes into the
channels using the quark interchange method. The mass and decay width of the
state are
MeV and
MeV, respectively, which indicates that it might be a good candidate for the recently observed
state. We also obtain an isospin partner state
with
MeV and
MeV, respectively. Future experimental search for
will be very helpful.
Sasaki, Yuji; Morita, Keisuke; Kitatsuji, Yoshihiro; Ito, Keisuke*; Yoshizuka, Kazuharu*
Solvent Extraction Research and Development, Japan, 28(2), p.121 - 131, 2021/00
Times Cited Count:2 Percentile:9.00(Chemistry, Multidisciplinary)High concentration of Cs is present in high-level radioactive waste. It is well-known that Cs is an alkali element and difficult to extract completely into an organic phase. Crown ether compounds are widely available for Cs extractants; DtBuDB18C6 (di--butyl-dibenzo-18crown6), was used in this study. Organic solvents used for the industrial applications, such as
-dodecane and 1-octanol, have low solubility concerning the compound; other solvents were employed and tested. In this study, ketone-, ether-, and ester-type solvents showed high solubility for DtBuDB18C6 and DtBuDB18C6, when dissolved in ketones and alcohols, exhibited relatively high Cs distribution ratios (
(Cs)), closely to 10.
Abe, Satoshi; Studer, E.*; Ishigaki, Masahiro; Shibamoto, Yasuteru; Yonomoto, Taisuke
Nuclear Engineering and Design, 368, p.110785_1 - 110785_14, 2020/11
Times Cited Count:14 Percentile:80.19(Nuclear Science & Technology)Sasaki, Yuji; Morita, Keisuke; Matsumiya, Masahiko*; Nakase, Masahiko*
Radiochimica Acta, 108(9), p.689 - 699, 2020/09
Times Cited Count:9 Percentile:65.08(Chemistry, Inorganic & Nuclear)The simultaneous separation of Am and Cm from lanthanides is important for atomic energy fields. All lanthanides, Am, and Cm can be extracted by diglycolamide (DGA). In addition, relatively high separation factors between An and Ln were obtained by the extraction system of TODGA, DTPA (diethylenetriamine-pentaacetic acid) and HNO. In this work, DTPA-BA (diethylenetriamine-triacetic-bisamide), which is an improved version of DTPA, was employed for the separation of Ln and An. A relatively high separation factor (approximately 8) for actinides/lanthanides was obtained. Then, the multi-step extraction was performed. Thus, the recoveries of 94.7% for Nd and 4.7% for Am and Cm in organic phase, and 5.3% Nd and 95.3% for Am and Cm in aqueous phase were obtained.
Rodriguez, D.; Koizumi, Mitsuo; Rossi, F.; Seya, Michio; Takahashi, Tone; Bogucarska, T.*; Crochemore, J.-M.*; Pedersen, B.*; Takamine, Jun
Journal of Nuclear Science and Technology, 57(8), p.975 - 988, 2020/08
Times Cited Count:4 Percentile:35.32(Nuclear Science & Technology)Collaborative Laboratories for Advanced Decommissioning Science; National Institute of Technology, Kisarazu College*
JAEA-Review 2019-033, 57 Pages, 2020/03
JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Dosimeter for Severe Radiation Environment near Reactor Pressure Vessel". Since the radiation level in the reactors and buildings of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (1F) is extremely high due to the accident, it is required to develop radiation measurement technology based on the needs at the 1F working site. In the previous studies, it has been verified that dosimeters using solar cell devices can be used for dose evaluation under high dose rate near the reactor pressure vessel because they have advantages such as unnecessity of a high-voltage source, ultra-compactness, lightweight, and high radiation resistance. Through this study, we will develop technologies towards practical application of revolutionary radiation measurement system based on the dose measurement technology utilizing solar cell devices.
Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*
JAEA-Review 2019-027, 70 Pages, 2020/01
JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Technology for Rapid Analysis of Strontium-90 with Low Isotopic Abundance Using Laser Resonance Ionization". In this study, we will develop a rapid analysis technique for strontium-90 using diode laser-based resonance ionization with elemental and isotopic selectivity. Strontium-90 is one of the major difficult-to-measure nuclides released into the environment due to the accident at Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi Nuclear Power Station. Our method is particularly intended for real samples which contain high concentrations of strontium stable isotopes such as marine samples.
Cubiss, J. G.*; Harding, R. D.*; Andreyev, A. N.; Althubiti, N.*; Andel, B.*; Antalic, S.*; Barzakh, A. E.*; Cocolios, T. E.*; Day Goodacre, T.*; Farooq-Smith, G. J.*; et al.
Physical Review C, 101(1), p.014314_1 - 014314_4, 2020/01
Times Cited Count:5 Percentile:44.30(Physics, Nuclear)The -decay branching ratio of 0.52(5)% from the ground state of
Pt to the ground state of the daughter nucleus
Os has been determined more precisely than before. The
Pt was produced as the
-decay granddaughter of
Hg which was produced and separated with the CERN-ISOLDE facility. The reduced
-decay width calculated with the present result has provided a new picture of the systematics for the
-decay width of neutron-deficient Pt isotopes.
Sasaki, Yuji; Morita, Keisuke
Progress in Nuclear Science and Technology (Internet), 5, p.27 - 32, 2018/12
no abstracts in English
Kitatani, Fumito; Tsuchiya, Harufumi; Toh, Yosuke; Hori, Junichi*; Sano, Tadafumi*; Takahashi, Yoshiyuki*; Nakajima, Ken*
KURRI Progress Report 2017, P. 99, 2018/08
Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Kuwabara, Kazumichi; Takayama, Yusuke
JAEA-Research 2015-025, 31 Pages, 2016/03
It is important to evaluate the stability of a repository for high-level radioactive waste not only during the design, construction and operation phases, but also during the post-closure period, for time frames likely exceeding several millennia or longer. The rock mass around the tunnels could be deformed through time in response to time dependent behavior. On the other hand, it was revealed that the chemical reaction of groundwater in a rock had an influence on the long-term behavior. An evaluation of the microcracks to have an influence on these mechanical and chemical coupled phenomena should be worked on chiefly. In fiscal year 2014, this study performed numerical analysis to examine the supersonic scattering attenuation decrement behavior in the crystalline rock and a measurement sequentially last year. The measurement of the head and surface waves were carried out. As a result, group speed was provided. On the other hand, the spread scattering analysis of the elastic wave by the FDTD (Finite Difference Time-Domain) method made a numerical analysis. However, a laboratory finding is different from expectation of the simulation, and crystal anisotropic influence of a microcrack and rock-forming minerals is thought about as a cause of this estrangement. Therefore it was revealed that it was necessary to examine these two points of influence more in future.
Ota, Masayuki; Sato, Satoshi; Ochiai, Kentaro; Konno, Chikara
Fusion Engineering and Design, 98-99, p.1847 - 1850, 2015/10
Times Cited Count:2 Percentile:16.17(Nuclear Science & Technology)International Reactor Dosimetry and Fusion File release 1.0 (IRDFF 1.0), has been released from the International Atomic Energy Agency (IAEA) recently. In order to validate and test IRDFF 1.0, IAEA has initiated a new Co-ordinated Research Project (CRP). Under this CRP, we have performed an integral experiment on a graphite pseudo-cylindrical slab assembly with DT neutron source at JAEA/FNS. The graphite assembly of 31.4 cm in equivalent radius and 61 cm in thickness is placed at a distance of about 20 cm from the DT neutron source. A lot of foils for the dosimetry reactions in IRDFF1.0 are inserted into the small spaces between the graphite blocks along the center axis of the assembly. After DT neutron irradiation, reaction rates for the dosimetry reactions are measured by the foil activation technique. This experiment is analyzed by using Monte Carlo neutron transport code MCNP5-1.40 with recent nuclear data libraries of ENDF/B-VII.1, JEFF-3.2, and JENDL-4.0. The experimental assembly and DT neutron source are modeled precisely in the MCNP calculation. The reaction rates calculated with IRDFF 1.0 as the response functions for the dosimetry reactions are compared with the experimental values. Also the calculations with JENDL Dosimetry File 99 (JENDL/D-99) are performed for comparison. The results calculated with IRDFF 1.0 show good agreement with the experimental results.