Materials science and fuel technologies of uranium and plutonium mixed oxide

Kato, Masato; Machida, Masahiko; Hirooka, Shun; Nakamichi, Shinya; Ikusawa, Yoshihisa; Nakamura, Hiroki; Kobayashi, Keita; Ozawa, Takayuki; Maeda, Koji; Sasaki, Shinji; et al.

Materials Science and Fuel Technologies of Uranium and Plutonium mixed Oxide, 171 Pages, 2022/10

https://doi.org/10.1201/9781003298205

Innovative and advanced nuclear reactors using plutonium fuel has been developed in each country. In order to develop a new nuclear fuel, irradiation tests are indispensable, and it is necessary to demonstrate the performance and safety of nuclear fuels. If we can develop a technology that accurately simulates irradiation behavior as a technology that complements the irradiation test, the cost, time, and labor involved in nuclear fuel research and development will be greatly reduced. And safety and reliability can be significantly improved through simulation of nuclear fuel irradiation behavior. In order to evaluate the performance of nuclear fuel, it is necessary to know the physical and chemical properties of the fuel at high temperatures. And it is indispensable to develop a behavior model that describes various phenomena that occur during irradiation. In previous research and development, empirical methods with fitting parameters have been used in many parts of model development. However, empirical techniques can give very different results in areas where there is no data. Therefore, the purpose of this study is to construct a scientific descriptive model that can extrapolate the basic characteristics of fuel to the composition and temperature, and to develop an irradiation behavior analysis code to which the model is applied.

PSTEP: Project for solar-terrestrial environment prediction

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

https://doi.org/10.1186/s40623-021-01486-1

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.

Multipole and superconducting state in PrIrZn probed by muon spin relaxation

Higemoto, Wataru; Ito, Takashi; Ninomiya, Kazuhiko; Onimaru, Takahiro*; Matsumoto, Keisuke*; Takabatake, Toshiro*

Physical Review B, 85(23), p.235152_1 - 235152_4, 2012/06

https://doi.org/10.1103/PhysRevB.85.235152

We performed muon spin rotation and relaxation measurements (SR) in caged structural heavy fermion system PrIrZn to elucidate magnetic and superconducting properties. Temperature independent SR spectra were observed below 1K, indicating that the phase transition at 0.11K is non-magnetic origin, most probably pure quadrupole ordering. In the superconducting phase, no sign of unconventional superconductivity, like a broken time reversal symmetry superconductivity, is seen below =0.05K. Moreover, we have observed spontaneous muon spin precession in a zero field in the paramagnetic phase below 15K, suggesting a novel coupling between Pr nuclei and muon realize in PrIrZn.

Collapsing processes of charge ordered structure in charge- and spin- frustrated ferrite YbFeO

Matsumoto, Keisuke*; Koyama, Tsukasa*; Mori, Shigeo*; Yoshii, Kenji; Ikeda, Naoshi*

Journal of Physics; Conference Series, 320, p.012085_1 - 012085_5, 2011/09

https://doi.org/10.1088/1742-6596/320/1/012085

In order to clarify the stability of charge ordered structure (CO) in charge- and spinfrustrated ferrite YbFeO, we have investigated changes of the CO structure by partial substitution of Mn for Fe in YbFeO by a transmission electron microscope (TEM), incombination with conventional dielectric measurement. It is revealed that subtle substitution of Mn for Fe in YbFeO destroyed drastically the CO structure with the wave vector of q=1/3 1/3 1/2 and, instead, induced polar clustering structure characterized by honeycomb shaped diffuse scatterings in the reciprocal space. The formation of polar clustering structure should be responsible for the characteristic dielectric dispersion.

Measurement of strain distribution around weld zone for railway carbody structure using high-energy synchrotron radiation

Matsumoto, Keisuke*; Shobu, Takahisa; Akiniwa, Yoshiaki*; Yagi, Tsuyoshi*; Yamamoto, Masataka*

Materials Science Forum, 571-572, p.321 - 326, 2008/00

Development of neutron spectrum measurement in high field using new nuclear emulsion, 2; Recognition algorithm for recoiled proton track based on three dimensional analysis of the novel nuclear emulsion

Takagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Morishima, Kunihiro*; Maeda, Shigetaka; Matsumoto, Tetsuro*

no journal, , 

In the novel nuclear emulsion development to measurement a neutron spectrum in high -ray field, in order to control -ray sensitivity, the ArBr grains of about 100 nm of particle diameter is used. The recoil proton track induced by neutron is recorded on nuclear emulsion. The track constituted by a silver grains child standing in a row discretely is recorded. The track extraction algorithm suitable for extraction of recoil proton was developed, and the characteristic was evaluated.

Magnetic/dielectric properties and charge ordering phenomenain YbFeMnO, 2

Matsumoto, Keisuke*; Hoshiyama, Takuya*; Oishi, Daisuke*; Akahama, Hiroshi*; Yoshii, Kenji; Kano, Jun*; Hanasaki, Noriaki*; Kambe, Takashi*; Ikeda, Naoshi*; Mori, Shigeo*

no journal, , 

We have investigated the physical properties of YbFeMnO, a derivative system of the electronic ferroelectric RFeO (R: rare earths). Electron diffraction measurements showed taht long-range charge ordering of the Fe-3d charges was observed at room temperature for x=0; this ordering is the origin of ferroelectricity. The x=0.1 oxide showed diffuse scattering patterns at room temperature, instead of the charge-ordered pattern. Thus, 5% Mn substitution can collapse the long-range charge ordering. We will also present the correlation between the magnetic/dielectric properties and the crystal structure.

Charge-order structure and physical properties of YbFeMnO

Matsumoto, Keisuke*; Matsuo, Yoji*; Oishi, Daisuke*; Akahama, Yuji*; Yoshii, Kenji; Hanasaki, Noriaki*; Kambe, Takashi*; Ikeda, Naoshi*; Kimizuka, Noboru*; Mori, Shigeo*

no journal, , 

We have investigated the charge-ordered structure and physical properties of YbFeMnO. Electron diffraction measurements showed a disappearance of charge-ordered structure of Fe ions by the Mn substitution. The Mn substitution also led to a monotonic decrease in magnetic transition temperature, low-temperature magnetization and dielectric constants. The results are explained in connection with several factors such as short-range ionic order.

An Experimental study on grease fluidity in a ball bearing using neutron imaging technology

Sakai, Kazumi*; Ogata, Rui*; Yamada, Shuhei*; Kimura, Nobuharu*; Matsumoto, Yoshihiro*; Kurita, Keisuke

no journal, , 

Rolling element bearings with grease lubrication are widely used for axis rotations in motors. Unlike liquid lubricants, the fluidity of semisolid greases in bearings plays an important role in bearing performances. The fluidity is often described as channeling and churning states. The states are well known, however, cannot be seen from outside bearings. Therefore, visualizations of greases in bearings are beneficial to understand the grease fluidity, however, methods for non-destructive observations of the inside of bearings are limited. The neutron imaging technology was applied for non-destructive observation of the grease fluidity inside a ball bearing in this study. The technology is based on a characteristic that neutron passes through heavy elements and interacts to light elements. In other words, neutron can identify lubricants with light elements inside the bearing with heavy elements.