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.

Development of technologies for enhanced analysis accuracy of fuel debris; Summary results of the 2020 fiscal year (Subsidy program for the project of decommissioning and contaminated water management)

Ikeuchi, Hirotomo; Koyama, Shinichi; Osaka, Masahiko; Takano, Masahide; Nakamura, Satoshi; Onozawa, Atsushi; Sasaki, Shinji; Onishi, Takashi; Maeda, Koji; Kirishima, Akira*; et al.

JAEA-Technology 2022-021, 224 Pages, 2022/10

JAEA-Technology-2022-021.pdf:12.32MB

A set of technology, including acid dissolving, has to be established for the analysis of content of elements/nuclides in the fuel debris samples. In this project, a blind test was performed for the purpose of clarifying the current level of analytical accuracy and establishing the alternative methods in case that the insoluble residue remains. Overall composition of the simulated fuel debris (homogenized powder having a specific composition) were quantitatively determined in the four analytical institutions in Japan by using their own dissolving and analytical techniques. The merit and drawback for each technique were then evaluated, based on which a tentative flow of the analyses of fuel debris was constructed.

Gallium-effect in a lead-free solder for silver-sheathed superconducting tape

Shamoto, Shinichi; Lee, M. K.*; Fujimura, Yuki; Kondo, Keietsu; Ito, Takashi; Ikeuchi, Kazuhiko*; Yasuda, Satoshi; Chang, L.-J.*

Materials Research Express (Internet), 8(7), p.076303_1 - 076303_6, 2021/07

https://doi.org/10.1088/2053-1591/ac10d2

Pb, Ga, and Ga doped lead free Sn-Ag-Cu solders are used to study the gallium effect for the low joint resistivity with silver sheathed DI BISCCO type H tapes. The results are reported.

Detailed deposition density maps constructed by large-scale soil sampling for -ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident

Saito, Kimiaki; Tanihata, Isao*; Fujiwara, Mamoru; Saito, Takashi*; Shimoura, Susumu*; Otsuka, Takaharu*; Onda, Yuichi*; Hoshi, Masaharu*; Ikeuchi, Yoshihiro*; Takahashi, Fumiaki; et al.

Journal of Environmental Radioactivity, 139, p.308 - 319, 2015/01

https://doi.org/10.1016/j.jenvrad.2014.02.014

Strong correlation among structural, electronic, and magnetic properties of SrFeMoO (0 x 1)

Yoshida, Koji*; Ikeuchi, Shinya*; Shimizu, Hajime*; Okayasu, Satoru; Suzuki, Takashi*

Journal of the Physical Society of Japan, 80(4), p.044716_1 - 044716_4, 2011/04

https://doi.org/10.1143/JPSJ.80.044716

We studied systematic changes of the structural, electric, and magnetic properties in SrFeMoO with 0 x 1, which bridges between a half-metallic double perovskite SrFeMoO (x = 0) and an antiferromagnetic metal SrFeO (= SrFeO: x = 1). The lattice volume at room temperature linearly decreases with x. The decline steeply enhances around x = 0.5, which is accompanied with a symmetry change from a tetragonal to a cubic crystal structure. In the same composition, we also found changes in the electronic ground state from a metal to an insulator and in the magnetic one from ferromagnetism to paramagnetism. These results indicate the strong correlation among the crystal structure, itinerant electrons and occurrence of ferromagnetic state in the double perovskite. In addition, the value of the critical composition could reflect peculiar physical changes with x.

Neutron detection by superconducting tunnel junctions on a LiBO single-crystal absorber

Nakamura, Tatsuya; Katagiri, Masaki; Ukibe, Masahiro*; Ikeuchi, Takashi*; Okubo, Masataka*

Nuclear Instruments and Methods in Physics Research A, 520(1-3), p.67 - 69, 2004/03

https://doi.org/10.1016/j.nima.2003.11.222

We succeeded in detecting neutrons using superconducting tunnel junctions (STJs) fabricated on a single crystal of LiBO. Neutrons are captured in the crystal by the nuclear reactions Li + n T+ + 4.78 MeV and B + n Li + + 2.3 MeV, and generated phonons propagate in the absorber and are measured by the STJs. We selected a single crystal of LiBO as the absorber material because of properties such as the large neutron cross-section of Li and B, low -ray sensitivity, short particle range in the substrate, and fast phonon velocity. Series-connected or multiple STJs on the crystal would enable two-dimensional neutron imaging with high detection efficiency, low gamma-ray background, and a high spatial resolution of a few microns. We demonstrate neutron detection by the STJs and show their X-ray response and neutron detection. The correlation in pulse heights between two junctions located 1.3mm apart clearly indicates the possibility of neutron imaging.

Development of efficient dissolution technology for FBR MOX fuel

Hoshino, Takanori; Ikeuchi, Hirotomo; Katsurai, Kiyomichi; Kondo, Yoshikazu*; Shibata, Atsuhiro; Sano, Yuichi; Watanabe, Masayuki; Suganuma, Takashi

no journal, , 

no abstracts in English

Construction of precise contamination maps in the Fukushima site

Saito, Kimiaki; Takahashi, Fumiaki; Kinouchi, Nobuyuki; Saegusa, Jun; Fujiwara, Mamoru*; Tanihata, Isao*; Saito, Takashi*; Shimoura, Susumu*; Ikeuchi, Yoshihiro*

no journal, ,