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Fukuda, Kodai
Annals of Nuclear Energy, 208(1), p.110748_1 - 110748_10, 2024/12
Arai, Yoichi; Watanabe, So; Watanabe, Masayuki; Arai, Tsuyoshi*; Katsuki, Kenta*; Agou, Tomohiro*; Fujikawa, Hisaharu*; Takeda, Keisuke*; Fukumoto, Hiroki*; Hoshina, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research B, 554, p.165448_1 - 165448_10, 2024/09
Hasemi, Hiroyuki; Kai, Tetsuya
JAEA-Testing 2024-001, 39 Pages, 2024/08
JAEA-Testing-2024-001.pdf:1.4MB
RAIM is an analysis code that analyzes resonance absorption spectra measured at pulsed neutron sources such as the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC) to obtain information on nuclear densities and temperatures. By calculating the convolution of the pulse functions of neutron beam and the resonance capture function that is based on the nuclear cross section data, RAIM reproduces the resonance absorption spectrum measured by a pulsed neutron source. Then, RAIM determines the density and temperature of specific nuclides in a sample by performing spectral fitting on the resonance absorption spectrum data. In addition, RAIM is developed to facilitate the analysis of resonance imaging data by minimizing the number of parameters for calculation setup and by providing scripts for processing many resonance absorption spectra measured by a two-dimensional detector at once. This manual explains how to install RAIM on a computer and how to simulate resonance absorption spectra and fit them to measured data.
Collaborative Laboratories for Advanced Decommissioning Science; University of Fukui*
JAEA-Review 2024-014, 112 Pages, 2024/08
JAEA-Review-2024-014.pdf:8.22MB
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 (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 "Clarification of debris formation conditions on the basis of the sampling data and experimental study using simulated fuel debris and reinforcement of the analytical results of severe accident scenario" conducted in FY2022. The present study aims to clarify the debris formation mechanism and utilize the results to refine the accident scenario. In the backward analysis of oxide debris formation, we succeeded in the formation of simulated fuel particle by the aerodynamic levitation method and ejection of melted oxides from tungsten pipe with a small hole. And we demonstrated the formation of simulated fuel debris of U1-No.15 obtained by the sampling in 1F.
Higa, Ryota*; Fujihara, Hiro*; Toda, Hiroyuki*; Kobayashi, Masakazu*; Ebihara, Kenichi; Takeuchi, Akihisa*
Materials Transactions, 65(8), p.899 - 906, 2024/08
It is indispensable to suppress hydrogen embrittlement (HE) to develop the strength of the Al-Zn-Mg alloy. Because intergranular fracture (IGF) is mainly observed when HE occurs in the alloy, we need to understand the IGF initiation to suppress HE. In the present study, we investigated the stress, strain, and H concentration, which influence the IGF initiation, in actual fractured regions by simulation of a crystal plasticity finite element method and H diffusion analysis in a 3D image-based model, which was created based on 3D polycrystalline microstructure data obtained from X-ray imaging technique. Combining the simulation and in-situ observation of the tensile test sample by X-ray CT, we examined the stress, strain, and H concentration, and discussed the IG crack initiation condition. As a result, it is revealed that stress normal to grain boundary induced by crystal plasticity dominates IG crack initiation while the accumulation of H due to stress has little impact on it.
Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*
JAEA-Review 2024-013, 48 Pages, 2024/07
JAEA-Review-2024-013.pdf:1.99MB
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 "Fuel debris criticality analysis technology using non-contact measurement method" conducted in FY2022. The purpose of research was to improve the fuel debris criticality analysis technology using non-contact measurement method by the development of the fuel debris criticality characteristics measurement system and the multi-region integral kinetic analysis code. It was performed by Tokyo Institute of Technology, National Institute of Advanced Industrial Science and Technology, and Nagaoka University of Technology as the second year of three years research project.
Department of Decommissioning and Waste Management
JAEA-Review 2024-004, 124 Pages, 2024/07
JAEA-Review-2024-004.pdf:3.39MB
This report describes the activities of Department of Decommissioning and Waste Management (DDWM) in Nuclear Science Research Institute (NSRI) in the period from April 1, 2022 to March 31, 2023. The report covers organization and missions of DDWM, outline and operation/maintenance of facilities which belong to DDWM, treatment and management of radioactive wastes, decommissioning activities, and related research and development activities which were conducted in DDWM. In FY2022 radioactive wastes generated from R&D activities in NSRI were treated safely. They were about 262 m
of combustible solid wastes and 113 m
of noncombustible solid wastes and 203 m of liquid wastes. After adequate treatment, 527 waste packages (in 200 L-drum equivalent) were generated. The total amounts of accumulated waste packages were 122,925 as of the end of FY2022 due to efforts of the restitution of waste packages to the Japan Radioisotope Association and volume reduction treatments of the stored waste packages. Decommissioning activities were carried out for the JAEA's Reprocessing Test Facility (JRTF). As for the R&D activities, studies on radiochemical analyses of wastes for disposal were continued. In order to pass the conformity review on the New Regulatory Requirements for waste management facilities, the Approval of the design and construction method was applied sequentially for the Nuclear Regulation Authority. The ministry of the Environment and Tokai-mura office requested JAEA to dispose of the contaminated soil generated by the accident of the Fukushima Daiichi Nuclear Power Station. The monitoring work at the playground was conducted during this period.
Risk Analysis Research Group, Reactor Safety Research Division, Nuclear Safety Research Center
JAEA-Data/Code 2024-006, 40 Pages, 2024/07
JAEA-Data-Code-2024-006.pdf:1.92MB
The Risk Analysis Research Group, Reactor Safety Research Division, Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness, Japan Atomic Energy Agency has been developing OSCAAR, a probabilistic risk assessment program for nuclear facility accidents. OSCAAR has the feature to calculate atmospheric concentrations of radioactive materials using an atmospheric dispersion model. This feature requires the input of meteorological data about wind speed, precipitation rate, atmospheric stability and so on. However, to use numerical weather prediction data created from the Japan Meteorological Agency (JMA) on OSCAAR, it is necessary to convert the data format to match OSCAAR input format in advance. Therefore, we developed GPV2OSC, a pre-processing program for OSCAAR, to create meteorological data converted from JMA weather prediction data format to OSCAAR input format when the target region and period are specified. This report describes the outline and usage of GPV2OSC.
Ninomiya, Kazuhiko*; Kubo, Kenya*; Inagaki, Makoto*; Yoshida, Go*; Takeshita, Soshi*; Tampo, Motonobu*; Shimomura, Koichiro*; Kawamura, Naritoshi*; Strasser, P.*; Miyake, Yasuhiro*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 333(7), p.3445 - 3450, 2024/07
Harjo, S.; Gong, W.; Kawasaki, Takuro
Nihon Zairyo Gakkai Dai-58-Kai X Sen Zairyo Kyodo Ni Kansuru Shimpojiumu Koen Rombunshu, p.51 - 54, 2024/07
Nemoto, Takahiro; Fujiwara, Yusuke; Arakawa, Ryoki; Choyama, Yuya; Nagasumi, Satoru; Hasegawa, Toshinari; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; et al.
JAEA-Technology 2024-003, 17 Pages, 2024/06
JAEA-Technology-2024-003.pdf:1.91MB
In order to investigate the cause of the increase in differential pressure in the primary helium circulator filter that occurred during the RS-14 cycle, a clogged filter was investigated. As a result of the investigation, deposits caused by silicone oil were confirmed on the surface of the filter element. These results revealed that the cause of filter clogging was silicone oil mixed into the primary system due to performance deterioration of the charcoal filter in the gas circulator of primary helium purification system. As a measure to prevent the recurrence of this event, in addition to the conventional management based on operating hours for replacing of charcoal filter in the gas circulator of primary helium purification system, we have established a new replacement plan for every three years.
Nuclear System Technology Review Committee
JAEA-Review 2024-018, 38 Pages, 2024/06
JAEA-Review-2024-018.pdf:1.46MB
In the R&D activities related to the Ministry of Education, Culture, Sports, Science and Technology's Innovative Nuclear R&D Program, "Development of Integrated Energy System Simulation Method Utilizing Small Modular Reactors for Enhanced System Decarbonization and Resilience," Japan Atomic Energy Agency (JAEA) established the "Nuclear System Technology Review Committee," consisting of experts in the subject areas, to obtain advice on the feasibility of deploying Design-standardized, Factory-built, Site-independent Small Modular Reactors (DFS-SMRs) in Japan and other countries. The Committee met three times during the 2021-2024 project period to discuss proposals for a regulatory framework for the potential commercial deployment of DFS-SMRs in Japan. The starting point for the Committee's discussions was the view that Japan's nuclear regulatory framework, like most other countries with existing commercial nuclear power plants in operation, focuses on large Light Water Reactors. Another consideration was the Committee's view on the basic structure of the regulatory framework, consistent with other regulatory initiatives around the world. Specifically, that the most effective regulatory frameworks need to be less prescriptive, less technology-dependent, and more performance-based. This report focuses on the United States, which has played a leading role in the deployment of SMRs and other advanced reactors, and summarizes the discussions regarding the proposal for a licensing framework for SMRs in Japan, an analysis of the gaps between Japan's current licensing framework and the proposed framework, and specific recommendations for closing the gaps. The Committee is hopeful that the changes to the regulatory framework proposed in this report will become a reality.
Omer, M.; Shizuma, Toshiyuki*; Hajima, Ryoichi*; Koizumi, Mitsuo
Journal of Applied Physics, 135(18), p.184903_1 - 184903_10, 2024/05
Ishida, Shinya; Fukano, Yoshitaka; Tobita, Yoshiharu; Okano, Yasushi
Journal of Nuclear Science and Technology, 61(5), p.582 - 594, 2024/05
Times Cited Count：1 Percentile：63.33(Nuclear Science & Technology)Tuya, D.; Nagaya, Yasunobu
Nuclear Science and Engineering, 198(5), p.1021 - 1035, 2024/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)In Monte Carlo neutron transport calculations for local response or deep penetration problems, some estimation of an importance function is generally required in order to improve their efficiency. In this work, a new recursive Monte Carlo (RMC) method, which is partly based on the original RMC method, for estimating an importance function for local variance reduction (i.e., source-detector type) problems has been developed. The new RMC method has been applied to two sample problems of varying degrees of neutron penetrations, namely a one-dimensional iron slab problem and a three-dimensional concrete-air problem. The biased Monte Carlo calculations with variance reduction parameters based on the obtained importance functions by the new RMC method have been performed to estimate detector responses in these problems. The obtained results are in agreement with those by the reference unbiased Monte Carlo calculations. Furthermore, the biased calculations offered an increase in efficiency on the order of 1 to 10
in terms of the figure of merit (FOM). The results also indicated that the efficiency increased as the neutron penetration became deeper.
Fujita, Tatsuya
Proceedings of Best Estimate Plus Uncertainty International Conference (BEPU 2024) (Internet), 14 Pages, 2024/05
The uncertainty analysis of PWR depletion test problem on the OECD/NEA/NSC LWR-UAM benchmark Phase II based on JENDL-5 was performed as a preliminary investigation. The random sampling was used to quantify the uncertainty of k-infinity and nuclide inventories, the cross section (XS), the fission product yield (FPY), the decay constant, and the decay branch ratio were randomly perturbed, and several times of SERPENT 2.2.1 calculations were performed. XSs in the ACE file were perturbed by the ACE file perturbation tool using FRENDY with the 56-group covariance matrix generated by NJOY2016.72. The perturbation quantity of independent FPY was evaluated using the FPY covariance matrix prepared in JENDL-5, and the perturbed cumulative FPY was reconstructed based on the relationship between the independent and cumulative FPYs. The decay constant was independently perturbed for each nuclide. To perturb the decay branch ratios, the covariance matrix was generated by applying the generalized least square method and randomly perturbed based on this covariance matrix in the same manner as the independent FPY. In general, the influence due to decay data was an order of magnitude smaller than the influences due to XS and FPY uncertainties. For the uncertainty of k-infinity and transuranic nuclide inventories, the influence due to XS uncertainty was dominant, and that due to FPY and decay data uncertainties was one or a few orders of magnitude smaller. On the other hand, for the uncertainty of FP nuclide inventories, the influence due to FPY uncertainty was almost the same or larger than that due to XS uncertainty. It was also confirmed that the influence due to either XS or FPY uncertainty became different for each FP nuclide. In future studies, the influence due to XS uncertainty on FP nuclides will be discussed because it was not prepared in JENDL-5 and not considered in the present paper.
Ayoub, A.*; Wainwright, Haruko*; Sansavini, G.*; Gauntt, R.*; Saito, Kimiaki
iScience (Internet), 27(4), p.109485_1 - 109485_15, 2024/04
Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2023-025, 117 Pages, 2024/03
JAEA-Review-2023-025.pdf:7.29MB
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 (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 FY2019, this report summarizes the research results of the "Development of extremely small amount analysis technology for fuel debris analysis" conducted in FY2022. Understanding the properties of fuel debris is necessary for handling, criticality control, storage control, etc. A key technique is the chemical analysis of actinide nuclides. We develop sample pretreatment technology and separation / analysis process required for chemical analysis. The purpose of this study is to streamline future planned fuel debris analysis. To promote 1F decommissioning, we will train human resources through on-the-job training.
Collaborative Laboratories for Advanced Decommissioning Science; Fukushima University*
JAEA-Review 2023-024, 109 Pages, 2024/03
JAEA-Review-2023-024.pdf:5.42MB
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 FY2019, this report summarizes the research results of the "Development of methodology combining chemical analysis technology with informatics technology to understand perspectives property of debris and tie-up style human resource development" conducted in FY2022. The present study aims to goal of this study is to implement a research plan relate to a development of combinational technology of new chemical analysis with informatics, and the aim is to develop new system for whole image estimation system using small quantities of information.
Choi, B.; Nishida, Akemi; Kawata, Manabu; Shiomi, Tadahiko; Li, Y.
JAEA-Research 2024-001, 206 Pages, 2024/03
JAEA-Research-2024-001.pdf:9.12MB
In the assessment of seismic safety and the design of building structures in nuclear facilities, lumped mass models have been used as standard methods. Recent advances in computer capabilities allow the use of three-dimensional finite element (3D FE) models to account for the 3D behavior of buildings, material nonlinearity, and the nonlinear soil-structure interaction effect. While 3D analysis method has many advantages, it is necessary to ensure its reliability as a new approach. The International Atomic Energy Agency performed an international benchmark study using the 3D FE analysis model for reactor building of Unit 7 at TEPCO's Kashiwazaki-Kariwa Nuclear Power Station based on recordings from the Niigataken Chuetsu-oki Earthquake in 2007. Multiple organizations from different countries participated in this study and the variation in their analytical results was significant, indicating an urgent need to improve the reliability of the analytical results by standardization of the analytical methods using 3D FE models. Additionally, it has been pointed out that it is necessary to understand the 3D behavior in the seismic fragility assessment of buildings and equipment, using realistic seismic response analysis method based on 3D FE models. In view of these considerations, a guideline for the seismic response analysis method using a 3D FE model was developed by incorporating the latest knowledge and findings in this area. The purpose of the guideline is to improve the reliability of the seismic response analysis method using 3D FE model of reactor buildings. The guideline consists of a main body, commentaries, and appendixes. The standard procedures, recommendations, key points to note, and technological bases for conducting seismic response analysis on reactor buildings using 3D FE models are provided in the guideline. In addition, the guideline will be revised reflecting the latest knowledge.
