Simanullang, I. L.*; Nakagawa, Naoki*; Ho, H. Q.; Nagasumi, Satoru; Ishitsuka, Etsuo; Iigaki, Kazuhiko; Fujimoto, Nozomu*
Annals of Nuclear Energy, 177, p.109314_1 - 109314_8, 2022/11
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
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.
Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2021, P. 93, 2022/07
In terms of nuclear transmutation studies of minor actinides in nuclear wastes, the present work selected Np among them and aimed to measure the thermal-neutron capture cross-section of Np using a well-thermalized neutron field by a neutron activation method because there have been discrepancies among reported cross-section data. A Np standard solution was used for irradiation samples. The thermal-neutron flux at an irradiation position was measured with flux monitors: Sc, Co, Mo, Ta and Au. The Np sample was irradiated together with the flux monitors for 30 minutes in the graphite thermal column equipped in the Kyoto University Research Reactor. The similar irradiation was repeated once more to confirm the reproducibility of the results. After irradiation, the Np samples were quantified using 312-keV gamma-ray emitted from Pa in radiation equilibrium with Np. The reaction rates of Np were obtained from the peak net counts of gamma-rays emitted from generated Np, and then the thermal-neutron capture cross-section of Np was found to be 173.84.7 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within a limit of uncertainty.
Fukahori, Tokio; Nakayama, Shinsuke; Katabuchi, Tatsuya*; Shigyo, Nobuhiro*
Nihon Genshiryoku Gakkai-Shi ATOMO, 64(7), p.413 - 414, 2022/07
The Investigation Advisory Committee on Nuclear Data monitors global nuclear research and development trends, and conducts collaborative nuclear data activities with domestic and foreign academic institutions in a wide range of fields. The aims are to contact, to exchange information, and to build an interdisciplinary cooperation system. Reported are the activities on the request list site, human resources development, and roadmap creation regarding nuclear data directly related to future nuclear data research activities, among the main activities in the 2019-2020 period.
Ishida, Shinya; Fukano, Yoshitaka
Nihon Kikai Gakkai Rombunshu (Internet), 88(911), p.21-00304_1 - 21-00304_11, 2022/07
In previous studies, the reliability and validity of the SAS4A code was enhanced by applying Phenomena Identification and Ranking Table (PIRT) approach to the Unprotected Loss of Flow (ULOF). SAS4A code has been developed to analyze the early stage of Core Disruptive Accident (CDA), which is named Initiating Phase (IP). In this study, PIRT approach was applied to Unprotected Transient over Power (UTOP), which was one of the most important and typical events in CDA as well as ULOF. The phenomena were identified by the investigation of UTOP event progression and physical phenomena relating to UTOP were ranked. 8 key phenomena were identified and the differences in ranking between UTOP and ULOF were clarified. The code validation matrix was completed and an SAS4A model, which was not validated in ULOF, was identified and validated. SAS4A code became applicable to various scenarios by using PIRT approach to UTOP and the reliability and validity of SAS4A code were significantly enhanced.
Dohi, Terumi; Iijima, Kazuki; Machida, Masahiko; Suno, Hiroya*; Omura, Yoshihito*; Fujiwara, Kenso; Kimura, Shigeru*; Kanno, Futoshi*
PLOS ONE (Internet), 17(7), p.e0271035_1 - e0271035_21, 2022/07
Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2022-002, 85 Pages, 2022/06
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 FY2020, this report summarizes the research results of the "Development of a new corrosion mitigation technology using nanobubbles toward corrosion mitigation in PCV system under the influence of //-rays radiolysis" conducted in FY2020. In this work, in order to ensure the long-term reliability of steel structures that ensure important confinement functions in the debris removal process, such as existing PCVs and newly constructed negative pressure maintenance systems and piping, corrosion phenomena in wet environments where - and -ray emitting nuclides come into contact with steel are clarified for the first time. At the same time, we will develop a new corrosion prevention technology that has excellent basic applicability to PCVs and has
Kawaguchi, Munemichi; Uno, Masayoshi*
Journal of Crystal Growth, 585, p.126590_1 - 126590_7, 2022/05
Phase-field mobility, , and crystal growth rates in crystallization of 11 oxides or mixed oxides in undercooled silicates, SiO and GeO liquids were calculated with a simple phase-field model (PFM), and material dependence of the was discussed. Ratios between experimental crystal growth rates and the PFM simulation with were confirmed to be proportional to a power of on the solid/liquid interface process during the crystal growth in a log-log plot. We determined that parameters, and , of the were to mJs and to , which were unique for the materials. It was confirmed that our PFM simulation with the determined reproduced quantitively the experimental crystal growth rates. The has a proportional relationship with the diffusion coefficient of a cation molar mass average per unit an oxygen molar mass at in a log-log graph. The depends on the sum of the cation molar mass per the oxygen molar mass, , in a compound. In , the decreases with the cation molar mass increasing. The assumed cause is that the B represents the degree of the temperature dependence of the . Since the cation molar mass is proportional to an inertial resistance of the cation transfer, the decreases with inverse of the cation molar mass. In crystallization of the silicates of heavy cation in , the saturates at approximately 0.67, which leads to .
Tsubota, Yoichi; Honda, Fumiya; Tokonami, Shinji*; Tamakuma, Yuki*; Nakagawa, Takahiro; Ikeda, Atsushi
Nuclear Instruments and Methods in Physics Research A, 1030, p.166475_1 - 166475_7, 2022/05
In the long-lasting decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), the dismantling of nuclear fuel debris (NFD) remaining in the damaged reactors is an unavoidable but significant issue with many technical difficulties. The dismantling is presumed to involve mechanical cutting, generating significant concentrations of particulates containing -radionuclides (-aerosols) that pose significant health risk upon inhalation. In order to minimize the radiation exposure of workers with -aerosols during the dismantling/decommissioning process at 1F, it is essential to monitor the concentration of -aerosols at the point of initial generation, i.e. inside the primary containment vessels (PCV) of the damaged reactors. Toward this end, an monitoring system for -aerosols ( alpha air monitor: IAAM) was developed and its technical performance was investigated under the conditions expected for the actual environments at 1F. IAAM was confirmed to fulfill four technical requirements: (1) steady operation under high humidity, (2) operation without using filters, (3) capability of measuring a high counting rate of -radiation, and (4) selective measurement of -radiation even under high radiation background with /-rays. IAAM is capable of selectively measuring -aerosols with a concentration of 3.3 10 Bq/cm or higher without saturation under a high humid environment (100%-relative humidity) and under high background with /-radiation (up to 100 mSv/h of -radiation). These results demonstrate promising potential of IAAM to be utilized as a reliable monitoring system for -aerosols during the dismantling of NFD, as well as the whole long-lasting decommissioning of 1F.
Okita, Shoichiro; Fukaya, Yuji; Sakon, Atsushi*; Sano, Tadafumi*; Takahashi, Yoshiyuki*; Unesaki, Hironobu*
Proceedings of International Conference on Physics of Reactors 2022 (PHYSOR 2022) (Internet), 9 Pages, 2022/05
Matsuda, Shohei; Yokoyama, Keiichi; Yaita, Tsuyoshi; Kobayashi, Toru; Kaneta, Yui; Simonnet, M.; Sekiguchi, Tetsuhiro; Honda, Mitsunori; Shimojo, Kojiro; Doi, Reisuke; et al.
Science Advances (Internet), 8(20), p.eabn1991_1 - eabn1991_11, 2022/05
no abstracts in English
Yomogida, Takumi; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
Scientific Reports (Internet), 12(1), p.7191_1 - 7191_10, 2022/05
Particles containing alpha () nuclides were identified from sediment in stagnant water at the torus room of the Fukushima Dai-ichi Nuclear Power Station (FDiNPS)'s Unit 2 reactor. Several uranium-bearing particles were identified by SEM observation. These particles contained Zr and other elements which constituted fuel cladding and structural materials. The U/U isotope ratio in the solid fractions that included U particles was consistent with the nuclear fuel in the Unit 2 reactor, which indicated that the U particles had been derived from nuclear fuel. The particles with alpha-emitters detected by alpha track analysis were several tens to several hundred m in size. The EDX spectra showed that these particles mainly comprised iron, which indicated Pu, Am, and Cm were adsorbed on the Fe-baring particles. This study clarifies that the major morphologies of U and other -nuclides were differed in the sediment of stagnant water in the torus room of FDiNPS's Unit 2 reactor.
Momma, Yuichiro*; Sakairi, Masatoshi*; Ueno, Fumiyoshi; Otani, Kyohei
Zairyo To Kankyo, 71(5), p.133 - 137, 2022/05
The effect of the corrosion inhibitor on the corrosion of steel under a thin solution layer was investigated. As a result of forming a thin solution layer with a thickness of 1.0-0.2 mm on the specimen, adding a mixed solution of sodium molybdate and aluminum lactate as a corrosion inhibitor, and performing electrochemical measurement, the corrosion inhibitor suppresses the anodic reaction. And in the thin solution layer, it was suggested that the morphology of the protective layer structure by the corrosion inhibitor changed according to the amount of liquid as compared with the bulk immersion.
Kirishima, Akira*; Terasaki, Mariko*; Miyakawa, Kazuya; Okamoto, Yoshihiro; Akiyama, Daisuke*
Chemosphere, 289, p.133181_1 - 133181_12, 2022/04
no abstracts in English
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
Journal of Nuclear Science and Technology, 11 Pages, 2022/04
The present study selected Np among radioactive nuclides and aimed to measure the thermal-neutron capture cross-section for Np in a well-thermalized neutron field by an activation method. A Np standard solution was used for irradiation samples. A thermal-neutron flux at an irradiation position was measured with neutron flux monitors: Sc, Co, Mo, Ta and Au. The Np sample and flux monitors were irradiated together for 30 minutes in the graphite thermal column equipped with the Kyoto University Research Reactor. The similar irradiation was carried out twice. After the irradiations, the Np samples were quantified using 312-keV gamma ray emitted from Pa in a radiation equilibrium with Np. The reaction rates of Np were obtained from gamma-ray peak net counts given by Np, and then the thermal-neutron capture cross-section of Np was found to be 173.84.4 barn by averaging the results obtained by the two irradiations. The present result was in agreement with the reported data given by a time-of-flight method within the limit of uncertainty.
Nagai, Yasuki*; Kawabata, Masako*; Hashimoto, Shintaro; Tsukada, Kazuaki; Hashimoto, Kazuyuki*; Motoishi, Shoji*; Saeki, Hideya*; Motomura, Arata*; Minato, Futoshi; Ito, Masatoshi*
Journal of the Physical Society of Japan, 91(4), p.044201_1 - 044201_10, 2022/04
Recently, Lu is considered as one of the most important medical RIs for treating neuroendocrine tumors. A plan to produce Lu with high purity by using enriched Yb samples with irradiation of deuteron beams in accelerators has been discussed. However, since the other Yb isotopes contained in the Yb sample interacts with deuterons, Lu isotopes other than Lu are produced as impurities. Since the purity of Lu is important for medical use, a method to evaluate the impurity of Lu has been required. In this study, we proposed a new method to estimate production yields of each Lu isotopes in Yb samples with arbitrary isotopic compositions by using excitation functions of Yb()Lu reactions and the particle transport calculation code PHITS. The method plays an important role in discussing the isotopic composition of enriched samples to produce high-purity Lu using accelerators.
Sato, Ikken; Yamaji, Akifumi*; Li, X.*; Madokoro, Hiroshi
Mechanical Engineering Journal (Internet), 9(2), p.21-00436_1 - 21-00436_17, 2022/04
Arai, Yosuke*; Kuroda, Kenta*; Nomoto, Takuya*; Tin, Z. H.*; Sakuragi, Shunsuke*; Bareille, C.*; Akebi, Shuntaro*; Kurokawa, Kifu*; Kinoshita, Yuto*; Zhang, W.-L.*; et al.
Nature Materials, 21(4), p.410 - 415, 2022/04
Momma, Yuichiro*; Sakairi, Masatoshi*; Ueno, Fumiyoshi; Otani, Kyohei
Zairyo To Kankyo, 71(4), p.121 - 125, 2022/04
The effect of solution layer thickness on the atmospheric corrosion of carbon steel was investigated using novel devices fabricated by a 3D printer. These novel devices allowed us to control the solution layer thickness precisely. Potentiodynamic polarization measurements were performed under thickness-controlled solution layer, and oxygen diffusion limiting current density () and anodic current density () were measured. As the solution layer become thinner, increased and decreased. This result indicates that corrosion accelerates when the solution layer becomes thinner. The diffusion coefficient of oxygen was calculated as 3.2010 cm s from the relationship between and solution layer thickness, and the critical diffusion thickness was estimated to be 0.87 mm.
Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*
JAEA-Review 2021-074, 104 Pages, 2022/03
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 FY2019, this report summarizes the research results of the "Basic study for on-line monitoring of tiny particles including alpha emitters by aerosol time-of-flight mass spectroscopy" conducted in FY2019 and FY2020. Since the final year of this proposal was FY2020, the results for two fiscal years were summarized. The present study aims to conduct a feasibility study of Aerosol time-of-flight mass spectroscopy (ATOFMS) to on-line measurement of tiny particles containing alpha emitters which might be dispersed in cutting the debris in reactors of the Fukushima Daiichi Nuclear Power Station for realizing their real-time monitoring. In FY2020, we prepared and analyzed the (U,Zr)O samples and the U solutions as model materials and measured the size distribution of the tiny