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JAEA Reports

Utilization of gamma ray irradiation at the WASTEF Facility

Sano, Naruto; Yamashita, Naoki; Watanabe, Masaya; Tsukada, Manabu*; Hoshino, Kazutoyo*; Hirai, Koki; Ikegami, Yuta*; Tashiro, Shinsuke; Yoshida, Ryoichiro; Hatakeyama, Yuichi; et al.

JAEA-Technology 2023-029, 36 Pages, 2024/03

JAEA-Technology-2023-029.pdf:2.47MB

At the Waste Safety Testing Facility (WASTEF), the gamma ray irradiation device "Gamma Cell 220" was relocated from the 4th research building of the Nuclear Science Research Institute in FY2019, and the use of gamma ray irradiation has begun. Initially, Fuel Cycle Safety Research Group, Fuel Cycle Safety Research Division, Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness, the owner of this device, conducted the tests as the main user, but since 2022, other users, including those outside the organization, have started using it. The gamma ray irradiation device "Gamma Cell 220" is manufactured by Nordion International Inc. in Canada. Since it was purchased in 1989, the built-in 60Co radiation source has been updated once, and safety research related to nuclear fuel cycles, etc. It is still used for this purpose to this day. This report summarizes the equipment overview of the gamma ray irradiation device "Gamma Cell 220", its permits and licenses at WASTEF, usage status, maintenance and inspection, and future prospects.

Journal Articles

Contrast dependence of scattering profiles for poly(ethylene glycol) in water; Investigation by small-angle neutron scattering with $$^{3}$$He spin filter and small-angle X-ray scattering

Ryoki, Akiyuki*; Watanabe, Fumi*; Okudaira, Takuya*; Takahashi, Shingo*; Oku, Takayuki; Hiroi, Kosuke; Motokawa, Ryuhei; Nakamura, Yo*

Journal of Chemical Physics, 160(11), p.114907_1 - 114907_9, 2024/03

Journal Articles

Quantum critical behavior of the hyperkagome magnet Mn$$_3$$CoSi

Yamauchi, Hiroki; Sari, D. P.*; Yasui, Yukio*; Sakakura, Terutoshi*; Kimura, Hiroyuki*; Nakao, Akiko*; Ohara, Takashi; Honda, Takashi*; Kodama, Katsuaki; Igawa, Naoki; et al.

Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02

Journal Articles

A Raman spectroscopy study of bicarbonate effects on UO$$_{2+x}$$

McGrady, J.; Kumagai, Yuta; Watanabe, Masayuki; Kirishima, Akira*; Akiyama, Daisuke*; Kimuro, Shingo; Ishidera, Takamitsu

Journal of Nuclear Science and Technology, 60(12), p.1586 - 1594, 2023/12

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Update of Bragg edge analysis software "GUI-RITS"

Oikawa, Kenichi; Sato, Hirotaka*; Watanabe, Kenichi*; Su, Y. H.; Shinohara, Takenao; Kai, Tetsuya; Kiyanagi, Yoshiaki*; Hasemi, Hiroyuki

Journal of Physics; Conference Series, 2605, p.012013_1 - 012013_6, 2023/10

Journal Articles

A Terrestrial SER Estimation Methodology Based on Simulation Coupled With One-Time Neutron Irradiation Testing

Abe, Shinichiro; Hashimoto, Masanori*; Liao, W.*; Kato, Takashi*; Asai, Hiroaki*; Shimbo, Kenichi*; Matsuyama, Hideya*; Sato, Tatsuhiko; Kobayashi, Kazutoshi*; Watanabe, Yukinobu*

IEEE Transactions on Nuclear Science, 70(8, Part 1), p.1652 - 1657, 2023/08

Single event upsets (SEUs) caused by neutrons is a reliability problem for microelectronic devices in the terrestrial environment. Acceleration tests using white neutron beam provide realistic soft error rates (SERs), but only a few facilities can provide white neutron beam in the world. If single-source irradiation applicable to diverse neutron source can be utilized for the evaluation of the SER in the terrestrial environment, it contributes to solve the shortage of beam time. In this study, we investigated the feasibility of the SER estimation in the terrestrial environment by any one of these measured data with the SEU cross sections obtained by PHITS simulation. It was found that the SERs estimated by our proposed method are within a factor of 2.7 of that estimated by the Weibull function. We also investigated the effect of simplification which reduce the computational cost in simulation to the SER estimation.

JAEA Reports

Removal of spent fuel sheared powder for decommissioning of Main Plant

Nishino, Saki; Okada, Jumpei; Watanabe, Kazuki; Furuuchi, Yuta; Yokota, Satoru; Yada, Yuji; Kusaka, Shota; Morokado, Shiori; Nakamura, Yoshinobu

JAEA-Technology 2023-011, 39 Pages, 2023/06

JAEA-Technology-2023-011.pdf:2.51MB

Tokai Reprocessing Plant (TRP) which shifted to decommissioning phase in 2014 had nuclear fuel materials such as the spent fuel sheared powder, the diluted plutonium solution and the uranium solution in a part of the reprocessing main equipment because TRP intended to resume reprocessing operations when it suspended the operations in 2007. Therefore, we have planned to remove these nuclear materials in sequence as Flush-out before beginning the decommissioning, and conducted removal of the spent fuel sheared powder as the first stage. The spent fuel sheared powder that had accumulated in the cell of the Main Plant (MP) as a result of the spent fuel shearing process was recovered from the cell floor, the shearing machine and the distributor between April 2016 and April 2017 as part of maintenance. Removing the recovered spent fuel sheared powder was conducted between June 2022 and September 2022. In this work, the recovered powder was dissolved in nitric acid at the dissolver in a small amount in order to remove it safely and early, and the dissolved solution was sent to the highly radioactive waste storage tanks without separating uranium and plutonium. Then, the dissolved solution transfer route was rinsed with nitric acid and water. Although about 15 years had passed since previous process operations, the removing work was successfully completed without any equipment failure because of the organization of a system that combines veterans experienced the operation with young workers, careful equipment inspections, and worker education and training. Removing this powder was conducted after revising the decommissioning project and obtaining approval from the Nuclear Regulation Authority owing to operating a part of process equipment.

JAEA Reports

Controlled release of radioactive krypton gas

Watanabe, Kazuki; Kimura, Norimichi*; Okada, Jumpei; Furuuchi, Yuta; Kuwana, Hideharu*; Otani, Takehisa; Yokota, Satoru; Nakamura, Yoshinobu

JAEA-Technology 2023-010, 29 Pages, 2023/06

JAEA-Technology-2023-010.pdf:3.12MB

The Krypton Recovery Development Facility reached an intended technical target (krypton purity of over 90% and recovery rate of over 90%) by separation and rectification of krypton gas from receiving off-gas produced by the shearing and the dissolution process in the spent fuel reprocessing at the Tokai Reprocessing Plant (TRP) between 1988 and 2001. In addition, the feasibility of the technology was confirmed through immobilization test with ion-implantation in a small test vessel from 2000 to 2002, using a part of recovered krypton gas. As there were no intentions to use the remaining radioactive krypton gas in the krypton storage cylinders, we planned to release this gas by controlling the release amount from the main stack, and conducted it from February 14 to April 26, 2022. In this work, all the radioactive krypton gas in the cylinders (about 7.1$$times$$10$$^{5}$$ GBq) was released at the rate of 50 GBq/min or less lower than the maximum release rate from the main stuck stipulated in safety regulations (3.7$$times$$10$$^{3}$$ GBq/min). Then, the equipment used in the controlled release of radioactive krypton gas and the main process (all systems, including branch pipes connected to the main process) were cleaned with nitrogen gas. Although there were delays due to weather, we were able to complete the controlled release of radioactive krypton gas by the end of April 2022, as originally targeted without any problems such as equipment failure.

Journal Articles

Neutron production in the interaction of 200-MeV deuterons with Li, Be, C, Al, Cu, Nb, In, Ta, and Au

Watanabe, Yukinobu*; Sadamatsu, Hiroki*; Araki, Shohei; Nakano, Keita; Kawase, Shoichiro*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.

EPJ Web of Conferences, 284, p.01041_1 - 01041_4, 2023/05

Intensive fast neutron sources using deuteron accelerators have been proposed for the study of medical RI production, radiation damage for fusion reactor materials, nuclear transmutation of radioactive waste, and so on. Neutron production data from various materials bombarded by deuterons are required for the design of such neutron sources. In the present work, we have conducted a systematic measurement of double-differential neutron production cross sections (DDXs) for a wide atomic number range of targets (Li, Be, C, Al, Cu, Nb, In, Ta, and Au) at an incident energy of 200 MeV in the Research Center for Nuclear Physics (RCNP), Osaka University. A deuteron beam accelerated to 200 MeV was transported to the neutron experimental hall and focused on a thin target foil. Emitted neutrons from the target were detected by two different-size EJ301 liquid organic scintillators located at two distances of 7 m and 20 m, respectively. The neutron DDXs were measured at six angles from 0$$^{circ}$$ to 25$$^{circ}$$). The neutron energy was determined by a conventional time-of-flight (TOF) method. The measured DDXs were compared with theoretical model calculations by the DEUteron-induced Reaction Analysis Code System (DEURACS) and PHITS. The result indicated that the DEURACS calculation provides better agreement with the measured DDXs than the PHITS calculation.

Journal Articles

Development of nondestructive elemental analysis system for Hayabusa2 samples using muonic X-rays

Osawa, Takahito; Nagasawa, Shunsaku*; Ninomiya, Kazuhiko*; Takahashi, Tadayuki*; Nakamura, Tomoki*; Wada, Taiga*; Taniguchi, Akihiro*; Umegaki, Izumi*; Kubo, Kenya*; Terada, Kentaro*; et al.

ACS Earth and Space Chemistry (Internet), 7(4), p.699 - 711, 2023/04

The concentrations of carbon and other major elements in asteroid samples provide very important information on the birth of life on the Earth and the solar-system evolution. Elemental analysis using muonic X-rays is one of the best analytical methods to determine the elemental composition of solid materials, and notably, is the only method to determine the concentration of light elements in bulk samples in a non-destructive manner. We developed a new analysis system using muonic X-rays to measure the concentrations of carbon and other major elements in precious and expectedly tiny samples recovered from the asteroid Ryugu by spacecraft Hayabusa2. Here we report the development process of the system in 4 stages and their system configurations, The analysis system is composed of a stainless-steel analysis chamber, an acrylic glove box for manipulating asteroid samples in a clean environment, and Ge semiconductor detectors arranged to surround the analysis chamber. The performance of the analysis system, including the background level, which is crucial for the measurement, was greatly improved from the first stage to the later ones. Our feasibility study showed that the latest model of our muonic X-ray analysis system is capable of determining the carbon concentration in Hayabusa2's sample model with an uncertainty of less than 10 percent in a 6-day measurement.

Journal Articles

Machine learning sintering density prediction model for MOX fuel pellet

Kato, Masato; Nakamichi, Shinya; Hirooka, Shun; Watanabe, Masashi; Murakami, Tatsutoshi; Ishii, Katsunori

Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(2), p.51 - 58, 2023/04

Uranium and Plutonium mixed oxide (MOX) pellets used as fast reactor fuels have been produced from several raw materials by mechanical blending method through processes of ball milling, additive blending, granulation, pressing, sintering and so on. It is essential to control the pellet density which is one of the important fuel specifications, but it is difficult to understand relationships among many parameters in the production. Database for MOX production was prepared from production results in Japan, and input data of eighteen types were chosen from production process and made a data set. Machine learning model to predict sintered density of MOX pellet was derived by gradient boosting regressor, and represented the measured sintered density with coefficient of determination of R$$^{2}$$=0.996

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2021

Nakada, Akira; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Futagawa, Kazuo; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; et al.

JAEA-Review 2022-078, 164 Pages, 2023/03

JAEA-Review-2022-078.pdf:2.64MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2021 to March 2022. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Liquid phase sintering of alumina-silica co-doped cerium dioxide CeO$$_{2}$$ ceramics

Vauchy, R.; Hirooka, Shun; Watanabe, Masashi; Yokoyama, Keisuke; Sunaoshi, Takeo*; Yamada, Tadahisa*; Nakamichi, Shinya; Murakami, Tatsutoshi

Ceramics International, 49(2), p.3058 - 3065, 2023/01

 Times Cited Count:4 Percentile:72.02(Materials Science, Ceramics)

Journal Articles

Free-surface flow simulations with floating objects using lattice Boltzmann method

Watanabe, Seiya*; Kawahara, Jun*; Aoki, Takayuki*; Sugihara, Kenta; Takase, Shinsuke*; Moriguchi, Shuji*; Hashimoto, Hirotada*

Engineering Applications of Computational Fluid Mechanics, 17(1), p.2211143_1 - 2211143_23, 2023/00

In tsunami inundations or slope disasters of heavy rain, a lot of floating debris or driftwood logs are included in the flows. The damage to structures from solid body impacts is more severe than the damage from the water pressure. In order to study free-surface flows that include floating debris, developing a high-accurate simulation code of free-surface flows with high performance for large-scale computations is desired. We propose the single-phase free-surface flow model based on the cumulant lattice Boltzmann method coupled with a particle-based rigid body simulation. The discrete element method calculates the contact interaction between solids. An octree-based AMR (Adaptive Mesh Refinement) method is introduced to improve computational accuracy and time-to-solution. High-resolution grids are assigned near the free surfaces and solid boundaries. We conducted two kinds of tsunami flow experiments in the 15 and 70 m water tanks at Hachinohe Institute of Technology and Kobe University to validate the accuracy of the proposed model. The simulation results have shown good agreement with the experiments for the drifting speed, the number of trapped wood pieces, and the stacked angles.

Journal Articles

Materials science and fuel technologies of uranium and plutonium mixed oxide

Kato, Masato; Machida, Masahiko; Hirooka, Shun; Nakamichi, Shinya; Ikusawa, Yoshihisa; Nakamura, Hiroki; Kobayashi, Keita; Ozawa, Takayuki; Maeda, Koji; Sasaki, Shinji; et al.

Materials Science and Fuel Technologies of Uranium and Plutonium mixed Oxide, 171 Pages, 2022/10

Innovative and advanced nuclear reactors using plutonium fuel has been developed in each country. In order to develop a new nuclear fuel, irradiation tests are indispensable, and it is necessary to demonstrate the performance and safety of nuclear fuels. If we can develop a technology that accurately simulates irradiation behavior as a technology that complements the irradiation test, the cost, time, and labor involved in nuclear fuel research and development will be greatly reduced. And safety and reliability can be significantly improved through simulation of nuclear fuel irradiation behavior. In order to evaluate the performance of nuclear fuel, it is necessary to know the physical and chemical properties of the fuel at high temperatures. And it is indispensable to develop a behavior model that describes various phenomena that occur during irradiation. In previous research and development, empirical methods with fitting parameters have been used in many parts of model development. However, empirical techniques can give very different results in areas where there is no data. Therefore, the purpose of this study is to construct a scientific descriptive model that can extrapolate the basic characteristics of fuel to the composition and temperature, and to develop an irradiation behavior analysis code to which the model is applied.

Journal Articles

Calculation of deuteron-induced reaction cross-sections for nuclear transmutation of long-lived fission products

Nakayama, Shinsuke; Furutachi, Naoya; Iwamoto, Osamu; Watanabe, Yukinobu*

NEA/NSC/R(2020)4 (Internet), p.345 - 349, 2022/10

Long-lived fission products (LLFPs) generated in nuclear reactors are strongly desired to be converted to stable or short-lived nuclides. Recently, it has been considered to transmute LLFPs by spallation reactions with high energy particles, and some experimental studies revealed that spallation reaction cross-sections induced by deuteron are larger than proton-induced ones. These results suggest the possibility that nuclear transmutation of LLFPs using deuteron beams is more efficient than one using proton beams. On the other hand, we have been developing a code system dedicated for deuteron-induced reactions, called DEURACS. DEURACS has been originally developed to contribute to the design of deuteron accelerator neutron sources. In the present study, we apply DEURACS to calculation of deuteron-induced spallation reactions on LLFPs. Through comparison with measured data, the applicability of DEURACS will be discussed.

Journal Articles

Clogging properties of HEPA filter induced by loading of soot from burned glove-box panel materials

Tashiro, Shinsuke; Ono, Takuya; Amano, Yuki; Yoshida, Ryoichiro; Watanabe, Koji*; Abe, Hitoshi

Nuclear Technology, 208(10), p.1553 - 1561, 2022/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

To contribute to the confinement safety evaluation of the radioactive materials in the Glove box (GB) fire accident, combustion tests with the Polymethyl methacrylate (PMMA) and the Polycarbonate (PC) as typical panel materials for the GB have been conducted with a relatively large scale apparatus. As the important data for evaluating confinement safety, the release ratio and the particle size distribution of the soot generated from the burned materials were obtained. Furthermore, the rise of the differential pressure ($$Delta$$P) of the high efficiency particle air (HEPA) filter by the soot loading was also investigated. As results, the release ratio of the soot from the PC was about seven times as large as the PMMA. In addition, it was found that the behavior of the rise of the $$Delta$$P with soot loading could be represented uniformly regardless of kinds of combustion materials by considering effect of the loading volume of the soot particle in the relatively low loading region.

Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:3 Percentile:80.29(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Measurement of nuclide production cross sections for proton-induced reactions on $$^{rm nat}$$Ni and $$^{rm nat}$$Zr at 0.4, 1.3, 2.2, and 3.0 GeV

Takeshita, Hayato*; Meigo, Shinichiro; Matsuda, Hiroki*; Iwamoto, Hiroki; Nakano, Keita; Watanabe, Yukinobu*; Maekawa, Fujio

Nuclear Instruments and Methods in Physics Research B, 527, p.17 - 27, 2022/09

 Times Cited Count:0 Percentile:56.43(Instruments & Instrumentation)

To improve accuracy of nuclear design of accelerator driven nuclear transmutation systems and so on, nuclide production cross sections on Ni and Zr were measured for GeV energy protons. The measured results were compared with PHITS calculations, JENDL/HE-2007 and so on.

Journal Articles

Investigation of physical properties of glove for glove-box and estimation of its life-time

Kobayashi, Daisuke; Yamamoto, Masahiko; Nishida, Naoki; Miyoshi, Ryuta; Nemoto, Ryo*; Hayashi, Hiroyuki*; Kato, Keisuke; Nishino, Saki; Kuno, Takehiko; Kitao, Takahiko; et al.

Nihon Hozen Gakkai Dai-18-Kai Gakujutsu Koenkai Yoshishu, p.237 - 240, 2022/07

All gloves attached to glove-box in Tokai Reprocessing Plant have a fixed expiration date and have to be replaced every 4-year. However, degrees of glove deterioration are different depending on its usage environment (frequency, chemicals, radiation, etc.), because of rubber products. Therefore, physical properties such as tensile strength, elongation, hardness of gloves are measured, and the life-time of gloves are estimated. As a result, gloves without any defects in its appearance have enough physical property for acceptance criteria of new glove. The extrapolated physical property of glove is sufficiently larger than the reported values of damaged glove. No deterioration in physical properties of gloves, that are periodically replaced without any defects in its appearance, is observed and the usable life-time of the glove is estimated to be 8 years.

794 (Records 1-20 displayed on this page)