Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 561

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

MAAP code analysis for the in-vessel phase of Fukushima-Daiichi Nuclear Power Station Unit 1 and comparison of the results among Units 1 to 3

Sato, Ikken; Yoshikawa, Shinji; Yamashita, Takuya; Shimomura, Kenta; Cibula, M.*; Mizokami, Shinya*

Nuclear Engineering and Design, 422, p.113088_1 - 113088_24, 2024/06

Journal Articles

Changes in molecular conformation and electronic structure of DNA under $$^{12}$$C ions based on first-principles calculations

Sekikawa, Takuya; Matsuya, Yusuke; Hwang, B.*; Ishizaka, Masato*; Kawai, Hiroyuki*; Ono, Yoshiaki*; Sato, Tatsuhiko; Kai, Takeshi

Nuclear Instruments and Methods in Physics Research B, 548, p.165231_1 - 165231_6, 2024/03

One of the main causes of radiation effects on the human body is thought to be damage to DNA, which carries genetic information. However, it is not fully understood what kind of molecular structural changes DNA undergoes upon radiation damage. Since it has been reported that various types of DNA damage are formed when DNA is irradiated, our group has investigated the relationship between DNA damage and various patterns of radiation-induced ionization induced by radiation. Although we have so far analyzed DNA damage in a simple system using a rigid body model of DNA, more detailed calculations are required to analyze the molecular structural changes in DNA, which are considered to be important in considering the effects on the human body. In this study, we attempted to clarify the molecular conformational changes of DNA using OpenMX, a first-principles calculation software that can discuss electronic states based on molecular structures. Specifically, we calculated the most stable structure, band dispersion, and wave function of DNA under the assumption that one and two electrons are ionized by various radiation. In the presentation, we will discuss the relationship between the energy dependence of each incident radiation type and the molecular conformational change of DNA. In addition, the radiation-induced changes in the basic physical properties of DNA (corresponding to the initial stage of DNA damage) will be discussed from the viewpoints of both radiation physics and solid state physics.

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

MAAP code analysis focusing on the fuel debris conditions in the lower head of the pressure vessel in Fukushima-Daiichi Nuclear Power Station Unit 3

Sato, Ikken; Yoshikawa, Shinji; Yamashita, Takuya; Shimomura, Kenta; Cibula, M.*; Mizokami, Shinya*

Nuclear Engineering and Design, 414, p.112574_1 - 112574_20, 2023/12

JAEA Reports

Segregation of components of molten core oxidic materials using cold crucible induction heating technique (Joint research)

Sudo, Ayako; M$'e$sz$'a$ros, B.*; Sato, Takumi; Nagae, Yuji

JAEA-Research 2023-007, 31 Pages, 2023/11

JAEA-Research-2023-007.pdf:3.61MB

For the criticality assessment of fuel debris generated by the accident in Fukushima Daiichi Nuclear Power Station, understanding of the elemental localization in fuel debris is important. Especially, the distribution of Fe and Gd, which may behave as potential neutron absorber materials in the fuel debris, is of particular important from the viewpoint of nuclear criticality safety. To investigate the localization tendency of Gd and Fe in molten core materials during solidification progress, liquefaction/solidification tests on core materials containing UO$$_{2}$$, ZrO$$_{2}$$, FeO, Gd$$_{2}$$O$$_{3}$$, and simulated fission products (MoO$$_{3}$$, Nd$$_{2}$$O$$_{3}$$, SrO, and RuO$$_{2}$$) and concrete (SiO$$_{2}$$, Al$$_{2}$$O$$_{3}$$, and CaO) were performed using cold crucible induction heating technique. During the test, the molten core materials gradually subsided and solidified from the bottom to the top of the melt. Elemental analysis showed that Fe content in the inner region increased approximately up to 3.4 times that in the bottom region. The concentration of Fe into the inner region was observed in all the samples regardless of the initial FeO composition, cooling rates, and phase separation. This suggests that FeO may be concentrated into the low temperature region, where the melt solidified later. In contrast, Gd content in the bottom region increased approximately up to 2.6 times that in the inner region. The concentration of Gd into the bottom region was observed when the initial Gd$$_{2}$$O$$_{3}$$ content was higher than 1 at.%. This suggests that Gd$$_{2}$$O$$_{3}$$ may be concentrated into the earlier solidified region. On the other hand, no significant localization was observed on the simulated fission products.

Journal Articles

Decontamination and solidification treatment on spent liquid scintillation cocktail

Watanabe, So; Takahatake, Yoko; Ogi, Hiromichi*; Osugi, Takeshi; Taniguchi, Takumi; Sato, Junya; Arai, Tsuyoshi*; Kajinami, Akihiko*

Journal of Nuclear Materials, 585, p.154610_1 - 154610_6, 2023/11

 Times Cited Count:0 Percentile:0.01

JAEA Reports

Stabilization of post-experiment nuclear materials in Plutonium Fuel Research Facility

Sato, Takumi; Otobe, Haruyoshi; Morishita, Kazuki; Marufuji, Takato; Ishikawa, Takashi; Fujishima, Tadatsune; Nakano, Tomoyuki

JAEA-Technology 2023-016, 41 Pages, 2023/09

JAEA-Technology-2023-016.pdf:2.74MB

This report summarizes the results of the stabilization treatments of post-experiment nuclear materials in Plutonium Fuel Research Facility (PFRF) from August 2018 to March 2021. Based on the management standards for nuclear materials enacted after the contamination accident that occurred at PFRF on June 6, 2017, the post-experiment nuclear materials containing plutonium (Pu): samples mixed with organic substances that cause an increase in internal pressure due to radiolysis (including X-ray diffraction samples mixed with epoxy resin and plutonium powder which caused contamination accidents), carbides and nitrides samples which is reactive in air, and chloride samples which may cause corrosion of storage containers, were selected as targets of the stabilization. The samples containing organic materials, carbides and nitrides were heated in an air flow at 650 $$^{circ}$$C and 950 $$^{circ}$$C for 2 hours respectively to remove organic materials and convert uranium (U) and Pu into oxides. U and Pu chlorides in LiCl-KCl eutectic melt were reduced and extracted into liquid Cd metal by a reaction with lithium (Li) -cadmium (Cd) alloy and converted to U-Pu-Cd alloy at 500 $$^{circ}$$C or higher. All of the samples were stabilized and stored at PFRF. We hope that the contents of this report will be utilized to consider methods for stabilizing post experiment nuclear materials at other nuclear fuel material usage facilities.

JAEA Reports

HFB-1 borehole survey data collection

Miyakawa, Kazuya; Hayano, Akira; Sato, Naomi; Nakata, Kotaro*; Hasegawa, Takuma*

JAEA-Data/Code 2023-009, 103 Pages, 2023/09

JAEA-Data-Code-2023-009.pdf:9.29MB
JAEA-Data-Code-2023-009-appendix1(DVD-ROM).zip:271.51MB
JAEA-Data-Code-2023-009-appendix2(DVD-ROM).zip:883.78MB
JAEA-Data-Code-2023-009-appendix3(DVD-ROM).zip:10.29MB

This borehole investigation was carried out to confirm the validity of the distribution of low flow areas deep underground estimated based on the geophysical survey in FY 2020, as a part of an R&D supporting program titled "Research and development on Groundwater Flow Evaluation Technology in Bedrock" under contract to the Ministry of Economy, Trade and Industry (2021, 2022 FY, Grant Number: JPJ007597). The borehole name is Horonobe Fossil seawater Boring-1 and is referred to as HFB-1 borehole. HFB-1 is a vertical borehole drilled adjacent to the Horonobe Underground Research Laboratory (URL), which was drilled from the surface to a depth of 200 m in FY2021 and from a depth of 200 m to 500 m in FY2022. This report summarizes information related to the drilling of HFB-1 and various data (rock core description, geophysical logging, chemical analysis, etc.) obtained from the borehole investigation.

Journal Articles

Numerical simulation method using a Cartesian grid for oxidation of core materials under steam-starved conditions

Yamashita, Susumu; Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Yoshida, Hiroyuki

Journal of Nuclear Science and Technology, 60(9), p.1029 - 1045, 2023/09

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

JAEA Reports

Document collection of the 39th Technical Special Committee on Fugen Decommissioning

Sato, Yuji; Miyamoto, Yuta; Awatani, Yuto; Yamamoto, Kosuke; Hatakeyama, Takumi

JAEA-Review 2023-002, 59 Pages, 2023/08

JAEA-Review-2023-002.pdf:8.75MB

"Fugen Decommissioning Engineering Center", in planning and carrying out our decommissioning technical development, organizes "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened domestic and international, as the central place in research and development base of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report consists of presentation paper are "Achievements and Considerations for Sampling and Analysis of Reactor Core Components", "Treatment of liquid scintillator waste liquid" and "Results and issues of rationalization of decontamination related to the clearance and considerations related to surface contamination monitoring" which is presented in the 39th Technical Special Committee on Fugen Decommissioning.

Journal Articles

Development of an iron(II) complex exhibiting thermal- and photoinduced double proton-transfer-coupled spin transition in a short hydrogen bond

Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Okazawa, Atsushi*; Shimada, Rintaro*; Sakamoto, Akira*; et al.

Journal of the American Chemical Society, 145(35), p.19177 - 19181, 2023/08

Journal Articles

Effect of decay heat on pyrochemical reprocessing of minor actinide transmutation nitride fuels

Hayashi, Hirokazu; Tsubata, Yasuhiro; Sato, Takumi

Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(3), p.97 - 107, 2023/08

The Japan Atomic Energy Agency has chosen nitride fuel as the first candidate for the transmutation of long-lived minor actinides (MA) using accelerator-driven systems (ADS). The pyrochemical method has been considered for reprocessing spent MA nitride fuels, because their decay heat should be very large for aqueous reprocessing. This study was conducted to investigate the effect of decay heat on the pyrochemical reprocessing of MA nitride fuels. On the basis of the estimated decay heats and the temperature limits of the materials that are to be handled in pyrochemical reprocessing, quantities adequate for handling in argon gas atmosphere were evaluated. From these considerations, we proposed that an electrorefiner with a diameter of 26 cm comprising 12 cadmium (Cd) cathodes with a diameter of 4 cm is suitable. On the basis of the size of the electrorefiner, the number necessary to reprocess spent MA fuels from 1 ADS in 200 days was evaluated to be 25. Furthermore, the amount of Cd-actinides (An) alloy to produce An nitrides by the nitridation-distillation combined reaction process was proposed to be about one-quarter that of Cd-An cathode material. The evaluated sizes and required numbers of equipment support the feasibility of pyrochemical reprocessing for MA nitride fuels.

Journal Articles

Study on chemical interaction between UO$$_{2}$$ and Zr at precisely controlled high temperatures

Shirasu, Noriko; Sato, Takumi; Suzuki, Akihiro*; Nagae, Yuji; Kurata, Masaki

Journal of Nuclear Science and Technology, 60(6), p.697 - 714, 2023/06

 Times Cited Count:0 Percentile:75.85(Nuclear Science & Technology)

Interaction tests between UO$$_{2}$$ and Zr were performed at precisely controlled high temperatures between 1840 and 2000 $$^{circ}$$C to understand the interaction mechanism in detail. A Zr rod was inserted in a UO$$_{2}$$ crucible and then heat-treated at a fixed temperature in Ar-gas flow for 10 min. After heating in the range of 1890 to 1930 $$^{circ}$$C, the Zr rod was deformed to a round shape, in which the post-analysis detected the significant diffusion of U into the Zr region and the formation of a dominant $$alpha$$-Zr(O) matrix and a small amount of U-Zr-O precipitates. The abrupt progress of liquefaction was observed in the sample heated at around 1940 $$^{circ}$$C or higher. The higher oxygen concentration in the $$alpha$$-Zr(O) matrix suppressed the liquefaction progress, due to the variation in the equilibrium state. The U-Zr-O melt formation progressed by the selective dissolution of Zr from the matrix, and the selective diffusion of U could occur via the U-Zr-O melt.

Journal Articles

Investigation of the electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy using X-ray photoelectron spectroscopy

Miyazaki, Hidetoshi*; Akatsuka, Tatsuyoshi*; Kimura, Koji*; Egusa, Daisuke*; Sato, Yohei*; Itakura, Mitsuhiro; Takagi, Yasumasa*; Yasui, Akira*; Ozawa, Kenichi*; Mase, Kazuhiko*; et al.

Materials Transactions, 64(6), p.1194 - 1198, 2023/06

We investigated the electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy using hard and soft X-ray photoemission spectroscopy and electronic band structure calculations to understand the mechanism of the phase stability of this material. Electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy showed a semi-metallic electronic structure with a pseudo-gap at the Fermi level. The observed electronic structure of the Mg$$_{99.2}$$Zn$$_{0.2}$$Y$$_{0.6}$$ alloy suggests that the presence of a pseudogap structure is responsible for phase stability.

Journal Articles

Comprehensive analysis and evaluation of Fukushima Daiichi Nuclear Power Station Unit 3

Yamashita, Takuya; Honda, Takeshi*; Mizokami, Masato*; Nozaki, Kenichiro*; Suzuki, Hiroyuki*; Pellegrini, M.*; Sakai, Takeshi*; Sato, Ikken; Mizokami, Shinya*

Nuclear Technology, 209(6), p.902 - 927, 2023/06

 Times Cited Count:0 Percentile:75.85(Nuclear Science & Technology)

Journal Articles

STEM-EELS/EDS chemical analysis of solute clusters in a dilute mille-feuille-type Mg-Zn-Y alloy

Sato, Yohei*; Egusa, Daisuke*; Miyazaki, Hidetoshi*; Kimura, Koji*; Itakura, Mitsuhiro; Terauchi, Masami*; Abe, Eiji*

Materials Transactions, 64(5), p.950 - 954, 2023/05

Dilute Mg-Zn-Y alloy with a mille-feuille structure (MFS) exhibits a mechanical strength comparable to Mg-Zn-Y alloy with long period stacking/ordered (LPSO) structure through kink deformation. In order to deepen understanding the thermal stability of the MFS-type Mg alloys, it is required to clarify the solute cluster structures composed of Zn and Y in solute enriched stacking faults (SESFs). In this study, electron energy-loss and energy dispersive X-ray spectroscopy based on scanning transmission electron microscopy (STEM-EELS/EDS) were conducted to investigate the electronic structure and composition of Zn and Y in the SESFs of the MFS-Mg alloy. Zn-L2,3 spectra indicated that the valence charges of Zn in the dilute Mg alloy were different from that of the LPSO-type Mg-Zn-Y alloy. In addition, the intensity ratio of L3/L2 in Y-L2,3 spectrum of the dilute MFS-Mg alloy was larger than that of the LPSO-Mg alloy, reflecting the electron occupancies of 4d3/2 and 4d5/2 orbitals of Y atoms were different from those of the LPSO-Mg alloys. STEM-EELS analysis of the SESF composition in the dilute MFS-Mg alloy indicated that the Zn/Y ratio should be lower than that of the LPSO-Mg alloy, which was confirmed also by STEM-EDS measurements. These results indicate that the cluster structure in the SESFs of the dilute MFS-Mg alloy should be different from the ideal Zn6Y8 cluster in the LPSO-type Mg-Zn-Y alloys.

Journal Articles

Observation of proton-transfer-coupled spin transition by single-crystal neutron-diffraction measurement

Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Wu, S.-Q.*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Sato, Osamu*

Physical Chemistry Chemical Physics, 25(17), p.12394 - 12400, 2023/05

Journal Articles

MAAP code analysis focusing on the fuel debris condition in the lower head of the pressure vessel in Fukushima-Daiichi Nuclear Power Station Unit 2

Sato, Ikken; Yoshikawa, Shinji; Yamashita, Takuya; Cibula, M.*; Mizokami, Shinya*

Nuclear Engineering and Design, 404, p.112205_1 - 112205_21, 2023/04

 Times Cited Count:0 Percentile:75.85(Nuclear Science & Technology)

Based on updated knowledge from plant-internal investigations, experiments and model simulations until now, the in-vessel phase of Fukushima-Daiichi Nuclear Power Station Unit 2 was analyzed using the MAAP code. In Unit 2, it is considered that the core material enthalpy was relatively low when it relocated to the lower plenum of the pressure vessel, then, cooled by the coolant and solidified there. Although the MAAP code tended to underestimate the degree of core-material oxidation during the relocation, this probable underestimation was compensated for by an existing study that was considered more reliable, so that more realistic debris conditions in the lower plenum could be obtained. Basic validity of the former prediction of the Unit 2 accident progression behavior was confirmed and detailed boundary condition for the later phase was provided. This boundary condition should be utilized for future studies addressing debris reheating process leading to lower head failure and debris relocation toward the pedestal.

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

Formation of MPd$$_{3+x}$$ (M = Gd, Np) by the reaction of MN with Pd and chlorination of MPd$$_{3+x}$$ using cadmium chloride

Hayashi, Hirokazu; Shibata, Hiroki; Sato, Takumi; Otobe, Haruyoshi

Journal of Radioanalytical and Nuclear Chemistry, 332(2), p.503 - 510, 2023/02

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

The formation of MPd$$_{3+x}$$ (M = Gd, Np) by the reaction of MN with Pd at 1323 K in Ar gas flow was observed. Cubic AuCu$$_3$$-type GdPd$$_{3.3}$$ (${it a}$ = 0.4081 $$pm$$ 0.0001 nm) and NpPd$$_3$$ (${it a}$ = 0.4081 $$pm$$ 0.0001 nm) were identified, respectively. The product obtained from the reaction of NpN with Pd contained additional phases including the hexagonal TiNi$$_3$$-type NpPd$$_3$$. Chlorination of the MPd$$_{3+x}$$ (M = Gd, Np) samples was accomplished by the solid-state reaction using cadmium chloride at 673 K in a dynamic vacuum. Pd-rich solid solution phase saturated with Cd and an intermetallic compound PdCd were obtained as by-products of MCl$$_3$$ formation.

561 (Records 1-20 displayed on this page)