Sintering and microstructural behaviors of mechanically blended Nd/Sm-doped MOX

Hirooka, Shun; Horii, Yuta; Sunaoshi, Takeo*; Uno, Hiroki*; Yamada, Tadahisa*; Vauchy, R.; Hayashizaki, Kohei; Nakamichi, Shinya; Murakami, Tatsutoshi; Kato, Masato

Journal of Nuclear Science and Technology, 60(11), p.1313 - 1323, 2023/11

https://doi.org/10.1080/00223131.2023.2192725

Additive MOX pellets are fabricated by a conventional dry powder metallurgy method. NdO and SmO are chosen as the additive materials to simulate the corresponding soluble fission products dispersed in MOX. Shrinkage curves of the MOX pellets are obtained by dilatometry, which reveal that the sintering temperature is shifted toward a value higher than that of the respective regular MOX. The additives, however, promote grain growth and densification, which can be explained by the effect of oxidized uranium cations covering to a pentavalent state. Ceramography reveals large agglomerates after sintering, and Electron Probe Micro-Analysis confirms that inhomogeneous elemental distribution, whereas XRD reveals a single face-centered cubic phase. Finally, by grinding and re-sintering the specimens, the cation distribution homogeneity is significantly improved, which can simulate spent nuclear fuels with soluble fission products.

Revealing the ion dynamics in LiGePS by quasi-elastic neutron scattering measurements

Hori, Satoshi*; Kanno, Ryoji*; Kwon, O.*; Kato, Yuki*; Yamada, Takeshi*; Matsuura, Masato*; Yonemura, Masao*; Kamiyama, Takashi*; Shibata, Kaoru; Kawakita, Yukinobu

Journal of Physical Chemistry C, 126(22), p.9518 - 9527, 2022/06

https://doi.org/10.1021/acs.jpcc.2c01748

Position dependency of the scattered intensity in the time-of-flight backscattering spectrometer DNA

Matsuura, Masato*; Yamada, Takeshi*; Tominaga, Taiki*; Kobayashi, Makoto*; Nakagawa, Hiroshi; Kawakita, Yukinobu

JPS Conference Proceedings (Internet), 33, p.011068_1 - 011068_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011068

The position dependence of the scattered intensity in the time-of-flight backscattering spectrometer DNA was investigated. A periodic structure for both vertical (pixel) and horizontal (PSD) directions was observed. The solar slit and over-bending of an analyzer crystal is discussed as a possible origin of the modulation in the intensity. We have developed software program for the systematic correction of the position-dependent intensity and offset energy for the elastic peak. This corrects the deviation from the true scattering intensity and improve the quality of the data, which includes the energy resolution.

Oxygen potential measurement of (U,Pu,Am)O and (U,Pu,Am,Np)O

Hirooka, Shun; Matsumoto, Taku; Kato, Masato; Sunaoshi, Takeo*; Uno, Hiroki*; Yamada, Tadahisa*

Journal of Nuclear Materials, 542, p.152424_1 - 152424_9, 2020/12

https://doi.org/10.1016/j.jnucmat.2020.152424

The measurement of oxygen potential was conducted at 1,673, 1,773, and 1,873 K for (UPuAm)O and at 1,873 and 1,923 K for (UPuAmNp)O by using a thermo-gravimeter and an oxygen sensor. Am inclusion in terms of substituting the U significantly increased the oxygen potential. Similarly, the inclusion of Np as a substitute for U increased the oxygen potential; however, the effect was not as large as that with the Pu or Am addition at the same rate. The results were analyzed via defect chemistry and certain defect formations were suggested in the reducing region and the near-stoichiometric region by plotting the relationship between PO and the deviation from the stoichiometry. The equilibrium constants of the defect reactions were arranged to reproduce the experiment such that Am/Np contents were included in the entropy with coefficients fitting the experimental data.

Development on laser cutting technique to suppress spatter particles aiming at disposal of radio-active waste

Naoe, Takashi; Teshigawara, Makoto; Futakawa, Masatoshi; Mizutani, Haruki; Muramatsu, Toshiharu; Yamada, Tomonori; Ushitsuka, Yuji*; Tanaka, Nobuatsu*; Yamasaki, Kazuhiko*

Proceedings of 8th International Congress on Laser Advanced Materials Processing (LAMP 2019) (Internet), 5 Pages, 2019/05

Laser cutting is one of the options in the disposal of radio-active waste, such as spallation neutron target vessel in J-PARC, etc. Due to unique characteristic of laser, such as non-contact system, it is more easily to provide remote-controlled system in comparison with conventional one, such as mechanical cutting machine, etc. However, a demerit of laser cutting is the sputter and fume caused by laser cutting, resulting in contamination with radio-active materials its surroundings. Recently it was developed that the spatter suppression technique by controlling laser beam profile in laser welding process. In order to apply this suppression technique to laser cutting, first of all, we attempted to observe the phenomenon at melting area during laser cutting using a high-speed video camera in order to make the physical model. The result showed that the appearance of fume and sputter were independently confirmed in the time evolution.

Temperature stability of PIN-PMN-PT ternary ceramics during pyroelectric power generation

Moro, Takuya*; Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Nakayama, Tadachika*; Takeda, Masatoshi*; Yamada, Noboru*; Nishihata, Yasuo; Fukuda, Tatsuo; et al.

Journal of Alloys and Compounds, 768, p.22 - 27, 2018/11

https://doi.org/10.1016/j.jallcom.2018.07.182

Detection of fatigue damage in stainless steel by EBSD analysis; Applicability of EBSD pattern quality

Kuroda, Masatoshi*; Kamaya, Masayuki*; Yamada, Teruaki*; Akita, Koichi

Nihon Kikai Gakkai Rombunshu (Internet), 83(852), p.17-00072_1 - 17-00072_7, 2017/07

https://doi.org/10.1299/transjsme.17-00072

In order to assess the fatigue damage of austenitic stainless steels by electron backscatter diffraction (EBSD) method more simply and easily, it should be more preferable to use a commercially available general-purpose EBSD analysis software rather than to employ an in-house developed EBSD analysis programme. In the present study, EBSD measurement was performed for Type 316 austenitic stainless steels subjected to cyclic loading, and the applicability of the EBSD parameter relevant to the pattern quality, which could be obtained by the commercial software, to the fatigue damage assessment was discussed by comparing the other EBSD parameter of the averaged local misorientation (Mave), which could be calculated by the in-house developed programme. As a result, the EBSD parameter relevant to the pattern quality, which signified the full width at half maximum (FWHM) of the histogram distribution of the image quality (IQ), was saturated at the beginning stage of the fatigue cycles, while Mave was increased monotonically with the cycles. This suggested that the FWHM of IQ could be useful to detect the initial stage of the fatigue damage, while Mave was suitable for the quantitative evaluation of the fatigue damage. XRD measurement was also carried out for the same samples employed in the EBSD measurement, and the XRD data was compared with the EBSD data to discuss the crystallographic mechanism of the change in the FWHM of IQ. As a result, it was found that the FWHM of the (111) XRD peak correlated well with the FWHM of IQ. Because the (111) plane in fcc metal such as austenitic stainless steel was most preferable for slip system, this implied that the change in the distribution of the pattern quality generated by the fatigue loading could be due to the slip deformation.

Conceptual design of engineering-scale plant applied the simplified MA-bearing fuel fabrication process

Yamada, Yoshikazu; Segawa, Tomoomi; Kato, Masato

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Next Generation Nuclear Systems for Sustainable Development (FR-17) (USB Flash Drive), 8 Pages, 2017/06

Japan Atomic Energy Agency (JAEA) have proposed the transmutation of minor actinides by fast reactors as a way to contribute significantly to the reduction of the volume and the potential radiotoxicity of radioactive wastes. In order to achieve this goal, it is important to introduce a fully automated and remote operation fuel fabrication plant with shielded hot cells and manipulators. JAEA's facilities including Plutonium Fuel Production Facility (PFPF) have fabricated MOX fuel. On the basis of the operational and technical experience obtained in above facilities, the conceptual design of engineering-scale plant applied the simplified MA-bearing fuel fabrication process with shielded hot cells and manipulator was done. It will be able to fabricate high MA-bearing fuel and to perform the maintenance and repairing of each equipment with manipulators. This plant will be constructed based on this concept and development plan.

Development of spin-wave-like dispersive excitations below the pseudogap temperature in the high-temperature superconductor LaSrCuO

Matsuura, Masato*; Kawamura, Sho*; Fujita, Masaki*; Kajimoto, Ryoichi; Yamada, Kazuyoshi*

Physical Review B, 95(2), p.024504_1 - 024504_6, 2017/01

https://doi.org/10.1103/PhysRevB.95.024504

Novel electrothermodynamic power generation

Kim, Y.*; Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Ogawa, Takashi*; Serizawa, Takeshi*; Tanaka, Hirohisa*; Baba, Masaaki*; Fukuda, Tatsuo; Yoshii, Kenji; et al.

Advanced Energy Materials, 5(13), p.1401942_1 - 1401942_6, 2015/07

https://doi.org/10.1002/aenm.201401942

An innovative electro-thermodynamic cycle based on temporal temperature variations using pyroelectric effect has been presented. Practical energy is successfully generated in both synchrotron X-ray diffraction measurements under controlled conditions and real engine dynamometer experiments. The main generating origin is revealed as a combination of a crystal structure change and dipole change phenomenon corresponds to the temperature variation. In particular, the electric field induced 180 domain switching extremely improves generating power, and the true energy breakeven with temperature variation is firstly achieved.