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JAEA Reports

Analysis of deposits inside the reactor at Fukushima Daiichi Nuclear Power Station in JFY2021; The Subsidy program of "Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris)" starting FY2021

Ikeuchi, Hirotomo; Sasaki, Shinji; Onishi, Takashi; Nakayoshi, Akira; Arai, Yoichi; Sato, Takumi; Ohgi, Hiroshi; Sekio, Yoshihiro; Yamaguchi, Yukako; Morishita, Kazuki; et al.

JAEA-Data/Code 2023-005, 418 Pages, 2023/12

JAEA-Data-Code-2023-005-01.pdf:24.59MB
JAEA-Data-Code-2023-005-02.pdf:32.18MB

For safe and steady decommissioning of Tokyo Electric Power Company Holdings' Fukushima Daiichi Nuclear Power Station (1F), information concerning composition and physical/chemical properties of fuel debris generated in the reactors should be estimated and provided to other projects conducting the decommissioning work including the retrieval of fuel debris and the subsequent storage. For this purpose, in FY2021, samples of contaminants (the wiped smear samples and the deposits) obtained through the internal investigation of the 1F Unit 2 were analyzed to clarify the components and to characterize the micro-particles containing uranium originated from fuel (U-bearing particles) in detail. This report summarized the results of analyses performed in FY2021, including the microscopic analysis by SEM and TEM, radiation analysis, and elemental analysis by ICP-MS, as a database for evaluating the main features of each sample and the probable formation mechanism of the U-bearing particles.

Journal Articles

Reaction of Np, Am, and Cm ions with CO$$_{2}$$ and O$$_{2}$$ in a reaction cell in triple quadrupole inductively coupled plasma mass spectrometry

Kazama, Hiroyuki; Konashi, Kenji*; Suzuki, Tatsuya*; Koyama, Shinichi; Maeda, Koji; Sekio, Yoshihiro; Onishi, Takashi; Abe, Chikage*; Shikamori, Yasuyuki*; Nagai, Yasuyoshi*

Journal of Analytical Atomic Spectrometry, 38(8), p.1676 - 1681, 2023/07

 Times Cited Count:0 Percentile:0.02

Journal Articles

ARKADIA; For the innovation of advanced nuclear reactor design

Ohshima, Hiroyuki; Asayama, Tai; Furukawa, Tomohiro; Tanaka, Masaaki; Uchibori, Akihiro; Takata, Takashi; Seki, Akiyuki; Enuma, Yasuhiro

Journal of Nuclear Engineering and Radiation Science, 9(2), p.025001_1 - 025001_12, 2023/04

This paper describes the outline and development plan for ARKADIA to transform advanced nuclear reactor design to meet expectations of a safe, economic, and sustainable carbon-free energy source. ARKADIA will realize Artificial Intelligence (AI)-aided integrated numerical analysis to offer the best possible solutions for the design and operation of a nuclear plant, including optimization of safety equipment. State-of-the-art numerical simulation technologies and a knowledge base that stores data and insights from past nuclear reactor development projects and R&D are integrated with AI. In the first phase of development, ARKADIA-Design and ARKADIA-Safety will be constructed individually, with the first target of sodium-cooled reactor. In a subsequent phase, everything will be integrated into a single entity applicable not only to advanced rectors with a variety of concepts, coolants, configurations, and output levels but also to existing light-water reactors.

Journal Articles

High-sensitive XANES analysis at Ce L$$_{2}$$-edge for Ce in bauxites using transition-edge sensors; Implications for Ti-rich geological samples

Li, W.*; Yamada, Shinya*; Hashimoto, Tadashi; Okumura, Takuma*; Hayakawa, Ryota*; Nitta, Kiyofumi*; Sekizawa, Oki*; Suga, Hiroki*; Uruga, Tomoya*; Ichinohe, Yuto*; et al.

Analytica Chimica Acta, 1240, p.340755_1 - 340755_9, 2023/02

 Times Cited Count:1 Percentile:34.31(Chemistry, Analytical)

no abstracts in English

Journal Articles

Recent improvements of the Particle and Heavy Ion Transport code System; PHITS version 3.33

Sato, Tatsuhiko; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuya, Yusuke; Matsuda, Norihiro; Hirata, Yuho; et al.

Journal of Nuclear Science and Technology, 9 Pages, 2023/00

The Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo radiation transport code that can simulate the behavior of most particle species with energies up to 1 TeV (per nucleon for ions). Its new version, PHITS3.31, was recently developed and released to the public. In the new version, the compatibility with high-energy nuclear data libraries and the algorithm of the track-structure modes have been improved. In this paper, we summarize the upgraded features of PHITS3.31 with respect to the physics models, utility functions, and application software introduced since the release of PHITS3.02 in 2017.

Journal Articles

Structure analysis of asymmetric interface using spin-contrast-variation neutron reflectometry

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Oku, Takayuki; Torikai, Naoya*; Niizeki, Tomotake*

Hamon, 32(4), p.165 - 168, 2022/11

We demonstrated the advantage of spin-contrast-variation neutron reflectometry on the structure analysis of buried interface between resin and porous silica layers. The interface structure was not reproduced by the normal Gaussian model, but by the asymmetric interface model where crosslinked polymer chains neither permeate the pore nor follow the surface roughness of the silica layer.

Journal Articles

Structure analysis of a buried interface between organic and porous inorganic layers using spin-contrast-variation neutron reflectivity

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Suzuki, Junichi*; Oku, Takayuki; Torikai, Naoya*; Niizeki, Tomotake*

Journal of Applied Crystallography, 55(5), p.1147 - 1153, 2022/10

AA2021-0903.pdf:1.06MB

 Times Cited Count:1 Percentile:31.49(Chemistry, Multidisciplinary)

Spin-contrast-variation neutron reflectivity obtains multiple reflectivity curves from a single sample and a single beam source. We used the strong point of the technique to reveal that, although methylated-perhydropolysilazane-derived silica layer has a higher porosity near the interface with acrylic urethane resin, the resin did not permeate the pore network.

Journal Articles

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

Journal Articles

The Japan Health Physics Society Guideline on Dose Monitoring for the Lens of the Eye

Yokoyama, Sumi*; Tsujimura, Norio; Hashimoto, Makoto; Yoshitomi, Hiroshi; Kato, Masahiro*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Sekiguchi, Hiroshi*; Koguchi, Yasuhiro*; Ono, Koji*; et al.

Journal of Radiation Protection and Research, 47(1), p.1 - 7, 2022/03

Background: In Japan, new regulations that revise the dose limit for the lens of the eye (the lens), operational quantities, and measurement positions for the lens dose were enforced in April 2021. Based on the international safety standards, national guidelines, the results of the Radiation Safety Research Promotion Fund of the Nuclear Regulatory Authority, and other studies, the Working Group of Radiation Protection Standardization Committee, the Japan Health Physics Society (JHPS) developed a guideline for radiation dose monitoring for the lens. Materials and Methods: The Working Group of the JHPS discussed the criteria of non-uniform exposure and the management criteria set to not exceed the dose limit for the lens. Results and Discussion: In July 2020, the JHPS guideline was published. The guideline consists of three parts: main text, explanations, and 26 questions. In the questions, the corresponding answers were prepared, and specific examples were provided to enable similar cases to be addressed. Conclusion: With the development of guideline on radiation dose monitoring of the lens, radiation managers and workers will be able to smoothly comply with revised regulations and optimise radiation protection.

Journal Articles

Improving the safety of the high temperature gas-cooled reactor "HTTR" based on Japan's new regulatory requirements

Hamamoto, Shimpei; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Sekita, Kenji; Watanabe, Shuji; Furusawa, Takayuki; Iigaki, Kazuhiko; et al.

Nuclear Engineering and Design, 388, p.111642_1 - 111642_11, 2022/03

 Times Cited Count:0 Percentile:33.72(Nuclear Science & Technology)

Following the Fukushima Daiichi Nuclear Power Plant accident in 2011, the Japan Atomic Energy Agency adapted High-Temperature engineering Test Reactor (HTTR) to meet the new regulatory requirements that began in December 2013. The safety and seismic classifications of the existing structures, systems, and components were discussed to reflect insights regarding High Temperature Gas-cooled Reactors (HTGRs) that were acquired through various HTTR safety tests. Structures, systems, and components that are subject to protection have been defined, and countermeasures to manage internal and external hazards that affect safety functions have been strengthened. Additionally, measures are in place to control accidents that may cause large amounts of radioactive material to be released, as a beyond design based accident. The Nuclear Regulatory Commission rigorously and appropriately reviewed this approach for compliance with the new regulatory requirements. After nine amendments, the application to modify the HTTR's installation license that was submitted in November 2014 was approved in June 2020. This response shows that facilities can reasonably be designed to meet the enhanced regulatory requirements, if they reflect the characteristics of HTGRs. We believe that we have established a reference for future development of HTGR.

Journal Articles

Development of guidelines on radiation protection for the lens of the eye in Japan

Yokoyama, Sumi*; Iwai, Satoshi*; Tsujimura, Norio; Hashimoto, Makoto; Yoshitomi, Hiroshi; Kato, Masahiro*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Sekiguchi, Hiroshi*; Koguchi, Yasuhiro*; et al.

Proceedings of 15th International Congress of the International Radiation Protection Association (IRPA-15) (Internet), 8 Pages, 2022/00

Journal Articles

Optimizing TiO$$_2$$ through water-soluble Ti complexes as raw material for controlling particle size and distribution of synthesized BaTiO$$_3$$ nanocubes

Nakashima, Koichi*; Hironaka, Kota*; Ouchi, Kazuma*; Ajioka, Mao*; Kobayashi, Yoshio*; Yoneda, Yasuhiro; Yin, S.*; Kakihana, Masato*; Sekino, Toru*

ACS Omega (Internet), 6(48), p.32517 - 32527, 2021/12

 Times Cited Count:4 Percentile:39.59(Chemistry, Multidisciplinary)

The BaTiO $$_3$$ nanoparticles synthesized by the hydrothermal method is examined by synchrotron X-ray and TEM observation. It was found that the particle size of synthesized BaTiO$$_3$$ depends on the particle size of the raw material of TiO$$_2$$. Succeeded in synthesizing 100 nm size BaTiO$$_3$$ nanocrystals showing uniform particle size distribution using TiO$$_2$$ nanoparticles with optimized particle size. The obtained BaTiO$$_3$$ nanocrystal is a tetragonal system of ferroelectric phase. A three-dimensional structure of BaTiO$$_3$$ nanoparticles could be obtained by the electron beam tomography.

Journal Articles

Validation of ATDMs at early after the lF accident using air dose rate estimated by airborne concentration and surface deposition density

Moriguchi, Yuichi*; Sato, Yosuke*; Morino, Yu*; Goto, Daisuke*; Sekiyama, Tsuyoshi*; Terada, Hiroaki; Takigawa, Masayuki*; Tsuruta, Haruo*; Yamazawa, Hiromi*

KEK Proceedings 2021-2, p.21 - 27, 2021/12

no abstracts in English

Journal Articles

Stabilization of size-controlled BaTiO$$_3$$ nanocubes via precise solvothermal crystal growth and their anomalous surface compositional reconstruction

Nakashima, Koichi*; Onagi, Kaito*; Kobayashi, Yoshio*; Ishigaki, Toru*; Ishikawa, Yoshihisa*; Yoneda, Yasuhiro; Yin, S.*; Kakihana, Masato*; Sekino, Toru*

ACS Omega (Internet), 6(14), p.9410 - 9425, 2021/04

 Times Cited Count:7 Percentile:61.28(Chemistry, Multidisciplinary)

We succeeded in synthesizing barium titanate nanocubes by hydrothermal synthesis. When the nanocubes were examined in detail using a scanning electron microscope, pulsed neutrons, and large synchrotron radiation, it was found that a reconstituted layer of titanium oxide was formed on the surface.

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018) (Translated document)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2020-007, 249 Pages, 2020/10

JAEA-Research-2020-007.pdf:15.83MB

The accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, Japan Atomic Energy Agency (JAEA) has been conducting "Long-term Assessment of Transport of Radioactive Contaminants in the Environment of Fukushima" concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Journal Articles

A Model intercomparison of atmospheric $$^{137}$$Cs concentrations from the Fukushima Daiichi Nuclear Power Plant accident, phase III; Simulation with an identical source term and meteorological field at 1-km resolution

Sato, Yosuke*; Sekiyama, Tsuyoshi*; Fang, S.*; Kajino, Mizuo*; Qu$'e$rel, A.*; Qu$'e$lo, D.*; Kondo, Hiroaki*; Terada, Hiroaki; Kadowaki, Masanao; Takigawa, Masayuki*; et al.

Atmospheric Environment; X (Internet), 7, p.100086_1 - 100086_12, 2020/10

The third model intercomparison project for investigating the atmospheric behavior of $$^{137}$$Cs emitted during the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident (FDNPP-MIP) was conducted. A finer horizontal grid spacing (1 km) was used than in the previous FDNPP-MIP. Nine of the models used in the previous FDNPP-MIP were also used, and all models used identical source terms and meteorological fields. Our analyses indicated that most of the observed high atmospheric $$^{137}$$Cs concentrations were well simulated, and the good performance of some models improved the performance of the multi-model ensemble. The analyses also confirmed that the use of a finer grid resolution resulted in the meteorological field near FDNPP being better reproduced. The good representation of the wind field resulted in the reasonable simulation of the narrow distribution of high deposition amount to the northwest of FDNPP and the reduction of the overestimation over the area to the south of FDNPP. In contrast, the performance of the models in simulating plumes observed over the Nakadori area, the northern part of Gunma, and the Tokyo metropolitan area was slightly worse.

Journal Articles

Estimation of air dose rate using measurement results of monitoring posts in Fukushima Prefecture

Seki, Akiyuki; Mayumi, Akie; Wainwright-Murakami, Haruko*; Saito, Kimiaki; Takemiya, Hiroshi; Idomura, Yasuhiro

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.158 - 164, 2020/10

We developed a method to estimate the temporal change of the air dose rate at the location with sparse (in time) measurements by using the continuous measurement data from the nearby monitoring post. This method determines an observation model from the correlation between sparse data at the target location and dense data at the monitoring post based on a hierarchical Bayesian model. The developed method was validated against the air dose rate measured at the monitoring posts in Fukushima prefecture from 2012 to 2017. The results showed that the developed method can predict the air dose rate at almost all target locations with an error rate of less than 10%.

Journal Articles

Summary of temporal changes in air dose rates and radionuclide deposition densities in the 80 km zone over five years after the Fukushima Nuclear Power Plant accident

Saito, Kimiaki; Mikami, Satoshi; Ando, Masaki; Matsuda, Norihiro; Kinase, Sakae; Tsuda, Shuichi; Yoshida, Tadayoshi; Sato, Tetsuro*; Seki, Akiyuki; Yamamoto, Hideaki*; et al.

Journal of Environmental Radioactivity, 210, p.105878_1 - 105878_12, 2019/12

 Times Cited Count:30 Percentile:81.17(Environmental Sciences)

Journal Articles

Temporal change in radiological environments on land after the Fukushima Daiichi Nuclear Power Plant accident

Saito, Kimiaki; Mikami, Satoshi; Ando, Masaki; Matsuda, Norihiro; Kinase, Sakae; Tsuda, Shuichi; Sato, Tetsuro*; Seki, Akiyuki; Sanada, Yukihisa; Wainwright-Murakami, Haruko*; et al.

Journal of Radiation Protection and Research, 44(4), p.128 - 148, 2019/12

Journal Articles

Intercomparison of numerical atmospheric dispersion prediction models for emergency response to emissions of radionuclides with limited source information in the Fukushima Dai-ichi Nuclear Power Plant accident

Iwasaki, Toshiki*; Sekiyama, Tsuyoshi*; Nakajima, Teruyuki*; Watanabe, Akira*; Suzuki, Yasushi*; Kondo, Hiroaki*; Morino, Yu*; Terada, Hiroaki; Nagai, Haruyasu; Takigawa, Masayuki*; et al.

Atmospheric Environment, 214, p.116830_1 - 116830_11, 2019/10

 Times Cited Count:6 Percentile:27(Environmental Sciences)

The utilization of numerical atmospheric dispersion prediction (NDP) models for accidental discharge of radioactive substances was recommended by a working group of the Meteorological Society of Japan. This paper is to validate the recommendation through NDP model intercomparison in the accidental release from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Emission intensity is assumed to be constant during the whole forecast period for the worst-case scenario unless time sequence of emission is available. We expect to utilize forecasts of surface air contaminations for preventions of inhalations of radioactive substances, and column-integrated amounts for mitigation of radiation exposure associated with wet deposition. Although NDP forecasts have ensemble spread, they commonly figure out relative risk in space and time. They are of great benefit to disseminating effective warnings to public without failure. The multi-model ensemble technique may be effective to improve the reliability.

357 (Records 1-20 displayed on this page)