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Kinoshita, Junichi; Sakamoto, Yu; Suzuki, Ichiro; Nakajima, Ryota; Morita, Yusuke; Irie, Hirobumi
JAEA-Technology 2024-027, 55 Pages, 2025/05
The Waste Treatment Facility No.2 has equipment that can process solid waste with relatively high radioactive levels generated within the Japan Atomic Energy Agency. This facility had been constructed under the old Building Standards Act. Seismic evaluation based on a new regulatory requirements enforced in December 2013 was executed, thereby, it was found that the seismic resistance requirements was insufficient according to the current Building Standards Act. Therefore, seismic reinforcement works was carried out from November 2018 to February 2020. In this report, seismic reinforcement design, works, test and inspection was complied.
Nagaya, Yasunobu
EPJ Nuclear Sciences & Technologies (Internet), 11, p.1_1 - 1_7, 2025/01
Japan Atomic Energy Agency (JAEA) has been developing a general-purpose continuous-energy Monte Carlo code MVP for nuclear reactor core analysis. Recently improvements to MVP have been focused on the development of an advanced neutronics/thermal-hydraulics coupling code. JAEA has also developed a new Monte Carlo solver Solomon for criticality safety analysis. Solomon aims to calculate the criticality of a damaged reactor core including fuel debris. This paper provides an overview of the capabilities and reviews recent applications of MVP and Solomon.
Ito, Tatsuya; Nagaishi, Ryuji; Kuwano, Ryo*; Godo, Masao*; Yoshida, Yoichi*
Radiation Physics and Chemistry, 226, p.112198_1 - 112198_5, 2025/01
Times Cited Count:0 Percentile:0.00(Chemistry, Physical)In recent years, the use of radiation-resistant resins of polyimide and polyether ether ketone becomes increasing as vessels for irradiation and unsealed radioisotope experiments. However, in our radiolysis experiments, the possibility of interaction between radiolysis products of water and the resin was found, suggesting concerns that the resin may affect reactions in water in radiation fields. To clarify the interaction, dichromate (CrO
) reduction and hydrogen peroxide (H
O
) formation in
-radiolysis of water were compared with and without the resin. The Cr
O
reduction amount in aqueous solution with the resin became larger than that without the resin at the same dose, indicating the promotion of Cr
O
reduction by the resin. On the other hand, the H
O
formation in pure water with and without an electron scavenger were almost independent of the presence of resin. These suggested the interaction between hydroxyl radical and the resin in contact with water in radiation fields.
Zhang, Y.-J.*; Umeda, Takemasa*; Morooka, Satoshi; Harjo, S.; Miyamoto, Goro*; Furuhara, Tadashi*
Metallurgical and Materials Transactions A, 55(10), p.3921 - 3936, 2024/10
Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*
JAEA-Review 2024-022, 59 Pages, 2024/09
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 FY2022. 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 FY2022, this report summarizes the research results of the "Investigation of effects of nano interfacial phenomena on dissolution aggregation of alpha nanoparticles by using micro nano technologies" conducted in FY2022. To ensure the safety of retrieval and storage management of nuclear fuel debris generated by the Fukushima Daiichi Nuclear Power Station accident, understanding of dissolution-denaturation behavior of the fuel debris alpha particles is one of the most crucial issues. This research aims to create novel microfluidic real-time measurement device for elucidating dissolution, aggregation, and denaturation processes of metal oxide nanoparticles under various solution environments, and clarify their nano-size and interfacial effects.
Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*
JAEA-Review 2024-012, 122 Pages, 2024/09
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 FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (hereafter referred to "1F"), 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 FY2021, this report summarizes the research results of the "Challenge of novel hybrid-waste-solidification of mobile nuclei generated in Fukushima Nuclear Power Station and establishment of rational disposal concept and its safety assessment" conducted in FY2022. The present study aims to establish the rational waste disposal concept of a variety of wastes generated in 1F based on the hybrid-waste-solidification by the Hot Isostatic Press (HIP) method. The ceramics form with target elements, mainly iodine, which is difficult to immobilize, and Minor actinides such as Am, an alphaemitter and heat source, are HIPed with well-studied materials such as SUS and zircaloy, which make the long-term stability evaluation and safety assessment possible.
Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*
JAEA-Review 2024-031, 75 Pages, 2024/08
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 FY2022. 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 FY2021, this report summarizes the research results of the "Research on radioactive aerosol control and decontamination at Fukushima Daiichi Nuclear Power Station decommissioning" conducted in FY2022. The present study aims to develop a safe laser decontamination system that can control aerosol diffusion during laser decontamination while simultaneously allowing advanced particle measurement and evaluation, in cooperation with a research group in the United Kingdom.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Suzuki, Hideya*
Journal of Nuclear Science and Technology, 61(7), p.883 - 893, 2024/07
Times Cited Count:4 Percentile:59.85(Nuclear Science & Technology)The mutual separation of Am and Cm is conducted using an alkyl-diamide amine (ADAAM) extractant. ADAAM exhibits extremely high separation factor with respect to Am and Cm separation (5.9) in a nitric acid--dodecane system. The batch-wise multistage extractions are performed using a system containing 0.2 M ADAAM and 1.5 M nitric acid. In this multistage extraction, an organic solvent give 96.5% and 1.06% yields of Am and Cm. After the mutual separation of Am and Cm, an additional extraction step is included to reduce the volumes of these aqueous and organic phases. Taking these steps, Am and Cm can be recovered in just two or three stages in the aqueous phases.
Watanabe, Tomoaki; Yamane, Yuichi
Journal of Nuclear Science and Technology, 61(7), p.958 - 966, 2024/07
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)The total fission energy released in a criticality accident involving fissile solution boiling tends to be high because the relatively high fission power continues during boiling. Simulating fission power change correctly during boiling seems essential to estimate the total fission energy. Fission power during boiling changes depending on fissile concentration and volume as the solution evaporates. In this study, we investigated the effect of concentration and volume change on estimated total fission energy for a long time of boiling. We introduced a model calculating the evaporation of fissile solution into the modified quasi-steady-state method to simulate power change during boiling. Three CRAC experiments and the Idaho Chemical Processing Plant (ICPP) criticality accident in 1959 were analyzed. As a result, the calculated energy considering concentration and volume change during boiling reproduced the measured energy well.
Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Mochimaru, Takanori*; Hori, Junichi*; Terada, Kazushi*; Koizumi, Mitsuo
Nuclear Instruments and Methods in Physics Research A, 1064, p.169465_1 - 169465_9, 2024/07
Times Cited Count:0 Percentile:0.00(Instruments & Instrumentation)Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Miyagawa, Takayuki; Uchita, Masato*; Hirayama, Tomoyuki*; Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; et al.
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07
To secure the seismic safety of the thin-walled mechanical components and piping under a severe design earthquake level, employing a three-dimensional (3D) seismic isolation system has been planned in a sodium-cooled fast reactor. The development results of the 3D isolation system have been reported in previous papers so far. Its update is reported in Part 7 to Part 9. Part 7 describes the overview of the development, the test plan of the isolation system in the assembled state of each element, and the performance of individual isolation elements. In part 8, the performance of the isolation device that each element was assembled into was investigated through loading tests. Part 9 reports analytical studies by an analysis model validated based on the insight of the test results.
Yoshida, Hidekazu*; Yamamoto, Koshi*; Asahara, Yoshihiro*; Maruyama, Ippei*; Karukaya, Koichi*; Saito, Akane*; Matsui, Hiroya; Mochizuki, Akihito; Jo, Mayumi*; Katsuta, Nagayoshi*; et al.
Communications Engineering (Internet), 3, p.67_1 - 67_10, 2024/05
A capability to permanently seal fluid flow-paths through bedrock, like boreholes or underground tunnels, is needed to ensure the long-term safety and effectiveness of many underground activities e.g. CO storage, hydrocarbon field abandonment, and nuclear waste disposal. Commonly used cementitious seals may not be sufficiently durable due to chemical and physical degradation. Learning from natural calcite (CaCO
) concretion formation, a more durable sealing method was developed using a "concretion-forming solvent". The method was tested by sealing flow-paths next to a tunnel in an underground research laboratory at 350 meters depth. The flow-paths initially sealed rapidly, then resealed after disturbance by earthquakes (M5.4). The treated rock recovered its very low natural permeability, demonstrating permanent sealing that is robust.
Micheau, C.; Ueda, Yuki; Motokawa, Ryuhei; Akutsu, Kazuhiro*; Yamada, Norifumi*; Yamada, Masako*; Moussaoui, S. A.*; Makombe, E.*; Meyer, D.*; Berthon, L.*; et al.
Journal of Molecular Liquids, 401, p.124372_1 - 124372_12, 2024/05
Times Cited Count:2 Percentile:60.60(Chemistry, Physical)Yamamoto, Tomohiko; Watakabe, Tomoyoshi; Miyazaki, Masashi; Okamura, Shigeki; Miyagawa, Takayuki; Yokoi, Shinobu*; Fukasawa, Tsuyoshi*; Fujita, Satoshi*
Mechanical Engineering Journal (Internet), 11(2), p.23-00393_1 - 23-00393_21, 2024/04
Watanabe, Tomoaki; Ueki, Taro; Suyama, Kenya
Proceedings of International Conference on Physics of Reactors (PHYSOR 2024) (Internet), 10 Pages, 2024/04
Solomon, a Monte Carlo solver being developed by JAEA, can calculate criticality in multi-material randomized systems for criticality evaluation of fuel debris. This study investigates the applicability of Solomon to critical mass calculations of fuel debris. We performed critical mass calculations of fuel randomization systems using Solomon. The fuel randomization systems, where burned fuels with different burnups and water are randomly distributed, were modeled by the incomplete randomized Weierstrass function (IRWF) model or voxel geometry in Solomon. Critical mass calculations of simple homogeneous and heterogeneous systems were also performed, and the critical sizes were compared to fuel randomization systems. The results showed that the fuel randomization causes significant variations in the critical mass. The obtained critical sizes were distributed close to a normal distribution, which made it reasonable to estimate the uncertainty of critical mass as the standard deviation. The critical sizes with uncertainty obtained by Solomon were smaller than those of a simple heterogeneous system. This indicates Solomon would be useful for estimating or evaluating a reasonable safety margin in criticality safety evaluations of fuel debris.
Sharma, A. K.*; Xu, R.*; Ahmed, Z.*; Miwa, Shuichiro*; Suzuki, Shunichi*; Kosuge, Atsushi
Journal of Aerosol Science, 177, p.106329_1 - 106329_21, 2024/03
Times Cited Count:11 Percentile:96.91(Engineering, Chemical)Collaborative Laboratories for Advanced Decommissioning Science; Ibaraki University*
JAEA-Review 2023-021, 112 Pages, 2024/02
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 "Contribution to Risk Reduction in Decommissioning Works by the Elucidation of Basic Property of Radioactive Microparticles" conducted from FY2018 to FY2021 (this contract was extended to FY2021). The present study aims to understand the basic properties (size, chemical composition, isotopic composition - including concentration of -emitters, electrostatic properties, and optical properties, etc.) of fine particles composed of silicate with insoluble properties which contain regions of highly concentrated radioactive cesium (Cs) released to the environment by the accident at the Fukushima Daiichi Nuclear Power Station of TEPCO in 2011 March.
Ikeuchi, Hirotomo; Koyama, Shinichi
Nihon Genshiryoku Gakkai-Shi ATOMO, 66(2), p.74 - 78, 2024/02
For the steady removal of fuel debris from the TEPCO's Fukushima Daiichi Nuclear Power Station (1F), it is an urgent issue to establish analysis technology and systems for fuel debris samples with unknown properties (unknown samples). For this purpose, through analysis tests using samples with known properties (simulated fuel debris) and discussions among experts, the validity of analysis results and the factors that cause errors has been identified. In addition to knowing the current level of analysis accuracy, studies are being conducted to understand and improve the influencing factors. This paper introduces a part of the development of infrastructure for analysis and evaluation technology of "nuclides and element content."
Hirota, Noriaki; Nakano, Hiroko; Fujita, Yoshitaka; Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Demura, Masahiko*; Kobayashi, Yoshinao*
The IV International Scientific Forum "Nuclear Science and Technologies"; AIP Conference Proceedings 3020, p.030007_1 - 030007_6, 2024/01
Dynamic strain aging (DSA) and intergranular stress corrosion cracking (intragranular SCC) occur in high temperature pressurized water simulating a boiling water reactor environment due to changes in dissolved oxygen (DO) content, respectively. In order to clearly understand the difference between these phenomena, the mechanism of their occurrence was summarized. As a result, it was found that DSA due to intragranular cracking occurred in SUS304 stainless steel at low DO 1 ppb, while DSA was suppressed at DO 100 to 8500 ppb due to the formation of oxide films on the surface. On the other hand, when DO was increased to 20000 ppb, the film was peeled from the matrix, O element diffused to the grain boundary of the matrix, resulting in intergranular SCC. These results are indicated that the optimum DO concentration must be adjusted to suppress crack initiation due to DSA and intergranular SCC.
Yoshida, Hidekazu*; Yamamoto, Koshi*; Asahara, Yoshihiro*; Maruyama, Ippei*; Karukaya, Koichi*; Saito, Akane*; Matsui, Hiroya; Mochizuki, Akihito; Katsuta, Nagayoshi*; Metcalfe, R.*
Powering the Energy Transition through Subsurface Collaboration; Proceedings of the 1st Energy Geoscience Conference (Energy Geoscience Conference Series, 1), 20 Pages, 2024/00
A capability to permanently seal fluid flow-paths in bedrock, such as natural faults/fractures, and damaged zones around boreholes/excavations, is needed to ensure the long-term safety and effectiveness of many underground activities. Cementitious materials are commonly used as seals, however these materials unavoidably undergo physical and chemical degradation, therefore potentially decreasing seal durability. In order to solve these problems, a more durable sealing method using concretion-forming resin has been developed by learning from natural calcite (CaCO) concretion formation. The sealing capability of resin was tested by
experiments on bedrock flow-paths in an underground research laboratory (URL), Hokkaido, Japan. The results showed a decrease the permeability rapidly down to 1/1,000 of the initial permeability due to calcite precipitation over a period of one year. During the experiment inland earthquakes occurred with foci below the URL (depths 2-7 km and maximum magnitude 5.4). Due to the earthquakes the hydraulic conductivities of the flow-paths sealed initially by concretion-forming resin increased. However, these flow-paths subsequently resealed rapidly, and within a few months recovered the same hydraulic conductivities as before the earthquakes. This new technique for rapidly producing long-lasting seals against fluid flow through rocks will be applicable to many kinds of underground activities.