Temperature effects on local structure, phase transformation, and mechanical properties of calcium silicate hydrates

Im, S.*; Jee, H.*; Suh, H.*; Kanematsu, Manabu*; Morooka, Satoshi; Koyama, Taku*; Nishio, Yuhei*; Machida, Akihiko*; Kim, J.*; Bae, S.*

Journal of the American Ceramic Society, 104(9), p.4803 - 4818, 2021/09

https://doi.org/10.1111/jace.17881

Development of experimental technology for simulated fuel-assembly heating to address core-material-relocation behavior during severe accident

Abe, Yuta; Yamashita, Takuya; Sato, Ikken; Nakagiri, Toshio; Ishimi, Akihiro

Journal of Nuclear Engineering and Radiation Science, 6(2), p.021113_1 - 021113_9, 2020/04

https://doi.org/10.1115/1.4045450

Spectroscopic measurements of L X-rays with a TES microcalorimeter for a non-destructive assay of transuranium elements

Nakamura, Keisuke; Morishita, Yuki; Takasaki, Koji; Maehata, Keisuke*; Sugimoto, Tetsuya*; Kiguchi, Yu*; Iyomoto, Naoko*; Mitsuda, Kazuhisa*

Journal of Low Temperature Physics, 193(3-4), p.314 - 320, 2018/11

https://doi.org/10.1007/s10909-018-1953-9

Effect of nitrogen concentration on nano-structure and high-temperature strength of 9Cr-ODS steel

Oka, Hiroshi; Tanno, Takashi; Otsuka, Satoshi; Yano, Yasuhide; Kaito, Takeji

Nuclear Materials and Energy (Internet), 16, p.230 - 237, 2018/08

https://doi.org/10.1016/j.nme.2018.05.010

observation of dislocation evolution in ferritic and austenitic stainless steels under tensile deformation by using neutron diffraction

Sato, Shigeo*; Kuroda, Asumi*; Sato, Kozue*; Kumagai, Masayoshi*; Harjo, S.; Tomota, Yo*; Saito, Yoichi*; Todoroki, Hidekazu*; Onuki, Yusuke*; Suzuki, Shigeru*

Tetsu To Hagane, 104(4), p.201 - 207, 2018/00

https://doi.org/10.2355/tetsutohagane.TETSU-2017-082

Local structure analysis of ZrN, and DyZyN surrogate materials for fast reactor nitride fuel

Yoneda, Yasuhiro; Tsuji, Takuya; Matsumura, Daiju; Okamoto, Yoshihiro; Takaki, Seiya; Takano, Masahide

Transactions of the Materials Research Society of Japan, 42(2), p.23 - 26, 2017/04

ZnN is a possible candidate for the diluent material for nitride fuels containing transuranium elements. Pellets of inert matrix material ZrN, and surrogate nitride fuel material DyZrN, are fabricated for the purpose of investigating the crystal structure. Lattice parameters of DyZrN followed the Vegard's low, in spite of the large lattice mismatch ( 7%) between DyN and ZrN. Local structure analysis was performed by X-ray absorption fine structure (XAFS) and atomic pair-distribution function (PDF) methods. The Zr-N nearest neighbor bond distance changed as changing the Dy composition. The complex local structure of DyN and ZrN is related to the preferable effects of ZrN.

Chemical states of trace-level strontium adsorbed on layered oxide by XPS and XANES under total reflection condition

Baba, Yuji; Shimoyama, Iwao

Photon Factory Activity Report 2016, 2 Pages, 2017/00

http://pfwww.kek.jp/acr/2016pdf/u_reports/pf16b0047.pdf

In order to elucidate the adsorption states of radioactive Sr-90 in soil, chemical bonding states of non-radioactive strontium adsorbed on layered oxide (mica) have been investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) spectroscopy. Since the number of atoms in radioactive Sr-90 is extremely small, the XPS and XANES were measured under total reflection condition of the incident X-rays. The detection limit in total reflection XPS was about 150 pg/cm, which corresponds to 300 Bq of Sr-90. The Sr 2p core-level energy in XPS shifted to lower energy with the decrease in the thickness of Sr layer. Also, the Sr 2p Sr 4d resonance energy in XANES shifts to lower energy with the decrease in the thickness. On the basis of a simple point charge model, it was elucidated that the chemical bond between Sr and mica surface becomes ionic with the decrease in the adsorbed amount of strontium.

Electronic structures of ferromagnetic CeAgSb; Soft X-ray absorption, magnetic circular dichroism, and angle-resolved photoemission spectroscopies

Saito, Yuji; Fujiwara, Hidenori*; Yamaguchi, Takashi*; Nakatani, Yasuhiro*; Mori, Takeo*; Fuchimoto, Hiroto*; Kiss, Takayuki*; Yasui, Akira*; Miyawaki, Jun*; Imada, Shin*; et al.

Journal of the Physical Society of Japan, 85(11), p.114713_1 - 114713_7, 2016/11

https://doi.org/10.7566/JPSJ.85.114713

We report on the electronic structures of ferromagnetic CeAgSb using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce 4 electrons. The linear dichroism effects in the Ce XAS spectra demonstrate the ground-state Ce 4 symmetry of , the spatial distribution of which is directed along the -axis. Nevertheless, ARPES spectra at the Ce 3-4 resonance show the momentum dependence of the intensity ratio between Ce 4 and 4 peaks in a part of the Brillouin zone, suggesting the non negligible momentum-dependent hybridization effect between the Ce 4 and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb.

Hydrostatic compression behavior and high-pressure stabilized -phase in -based titanium aluminide intermetallics

Liss, K.-D.*; Funakoshi, Kenichi*; Dippenaar, R. J.*; Higo, Yuji*; Shiro, Ayumi*; Reid, M.*; Suzuki, Hiroshi; Shobu, Takahisa; Akita, Koichi

Metals, 6(7), p.165_1 - 165_22, 2016/07

https://doi.org/10.3390/met6070165

Titanium aluminides find application in modern light-weight, high-temperature turbines, such as aircraft engines, but suffer from poor plasticity during manufacturing and processing. Huge forging presses enable materials processing in the 10 GPa range and hence, it is necessary to investigate the phase-diagrams of candidate materials under these extreme conditions. Here we report on an in-situ synchrotron X-ray diffraction study in a large-volume-press of a modern ( + ) two-phase material, Ti-45Al-7.5Nb-0.25C, under pressures up to 9.6 GPa and temperatures up to 1686 K. At room temperature, the volume response to pressure is accommodated by the transformation rather than volumetric strain, expressed by apparently high bulk moduli of both constituent phases. Crystallographic aspects, specifically lattice strain and atomic order are discussed in detail. It is interesting to note that this transformation takes place despite an increase in atomic volume, which is due to the high ordering energy of . Upon heating under high pressure, both the eutectoid and -solvus transition temperatures are elevated, and a third, cubic -phase is stabilized above 1350 K. Earlier research has shown that this -phase is very ductile during plastic deformation, essential in near-conventional forging processes. Here, we were able to identify an ideal processing window for near-conventional forging, while the presence of the detrimental -phase is not present under operating conditions. Novel processing routes can be defined from these findings.

Development of BDI behavior evaluation method in the fast reactor fuel assembly; Improvement of out-of-pile bundle compression test technology

Higashiuchi, Atsushi; Ishimi, Akihiro; Katsuyama, Kozo; Uwaba, Tomoyuki; Ichikawa, Shoichi

JAEA-Technology 2015-057, 72 Pages, 2016/03

JAEA-Technology-2015-057.pdf:36.91MB

Bundle-duct interaction (BDI) in fast reactors (FRs) is one of the limiting factors for burnup. To study the high performance fuel for FR fuel, it is important to establish the method to predict accurately the BDI behavior for the fuel assembly of large-diameter fuel pins. Therefore, it was adopted a new method that the bundle compression test apparatus is placed outside the cell, the bundle specimen is put in the airtight container for contamination prevention, and the bundle specimen is carried in the cell for internal observation by X-ray CT examination apparatus. From the result of this test, it was confirmed that the new method of out-of-pile bundle compression test is carried out as it was before. The results of this test are available to study integrity assessment of fast reactor fuel, validation of the BDI analysis code and substantiation of the safety design guidelines of fast reactor. In addition, it is possible to reflect in the BDI behavior evaluation for "ASTRID".