Araki, Shohei; Gunji, Satoshi; Arakaki, Yu; Yoshikawa, Tomoki; Murakami, Takahiko; Kobayashi, Fuyumi; Izawa, Kazuhiko; Suyama, Kenya
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 8 Pages, 2023/10
New experiments simulating fuel debris in the new criticality assembly, STACY, are designed to contribute to the validation of criticality calculations for criticality control of the fuel debris in the Fukushima Daiichi Nuclear Power Plant accident. In the new STACY experiment, a two-region core consisting of a driver region and a test region was investigated in order to configure a debris-simulated core with under-moderation condition (lattice pitch 1.27-cm) having the constraint of available fuel rod number. The test region with a 1.27-cm lattice pitch is surrounded by the driver region, in which fuel rods are arranged in a checkerboard pattern on a 1.27-cm lattice plate, with a 1.80-cm lattice pitch. Neutron spectra and sensitivity were calculated by using MCNP6 and ENDF/B-VII. The core which has a 1717 test region with 373 fuel rods is the largest two-region core under the constraint. It was found that the core which has a 1717 test region can simulate the neutron spectra of under-moderation condition in a 1313 region inside the test region with the root-mean square percentage error of less than 5%. It was also confirmed that the sensitivity of Si and Ca (n,) reactions when the concrete simulant, was loaded could be simulated.
Murase, Satoshi*; Yoshikawa, Yumi*; Fujiwara, Kosuke*; Fukada, Yukimasa*; Teranishi, Takashi*; Kano, Jun*; Fujii, Tatsuo*; Inada, Yasuhiro*; Katayama, Misaki*; Yoshii, Kenji; et al.
Journal of Physics and Chemistry of Solids, 162, p.110468_1 - 110468_6, 2022/03
We report a trial of the valence control for mixed valence iron triangular oxide YbFeO in order to develop an effective technique to control the frustration of charges in strongly correlated electron systems. The electro-chemical doping of Li into YbFeO was examined on the cell type sample similar to the Li-ion secondary battery cell. Systematic change of the lattice constant, Fe-Fe and Fe-Yb distance were observed with Li doping. Maximum value of the doping was over 300 mAh/g. An EXAFS experiment indicated that Li positioned between Yb octahedron layer (U-layer) and Fe-bipyramidal layer (W-layer). However, detailed change of iron valence state of YbFeO was not clearly observed because of the superimpose of the signal from iron metal nano particles in XANES observation. The results indicate that the electrochemical method might be one of the potential technique to control the frustration of charges in YbFeO.
Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Mano, Tadashi; Yoshikawa, Hideki; Fukunaga, Sakae*; Yui, Mikazu; Yamagata, Junji*; Asano, Hidekazu*; Yamanaka, Yumiko*
PNC TN8410 94-117, 60 Pages, 1993/03
Maekawa, Tomoyuki; Seki, Masakazu; Sumiya, Masato; Araki, Shohei; Murakami, Takahiko; Hasegawa, Kenta; Yoshikawa, Tomoki; Mori, Takashi*; Ishii, Junichi; Kobayashi, Fuyumi; et al.
no journal, ,
As previously reported, to clarify critical characteristics of fuel debris, the Static Experiment Critical Facility (STACY) is being converted to the heterogenous thermal system using fuel rods and light water moderator from the homogenous system using solution fuel. Seismic reinforcement of the support structure of the core tank started in 2022. This report presents progress on manufacture and construction of the modified STACY in 2021 and 2022.
Murase, Satoshi*; Yoshikawa, Yumi*; Fukada, Yukimasa*; Ikeda, Naoshi*; Teranishi, Takashi*; Kano, Jun*; Fujii, Tatsuo*; Tsuji, Takuya; Yoshii, Kenji
no journal, ,