Effects of melting and coagulating conditions on the structure of simulated waste glasses

Nagai, Takayuki; Aoyama, Yusuke; Okamoto, Yoshihiro; Hasegawa, Takehiko*; Sato, Seiichi*; Kikuchi, Tetsuya*; Hatakeyama, Kiyoshi*

JAEA-Research 2025-012, 43 Pages, 2026/01

JAEA-Research-2025-012.pdf:6.99MB

In the vitrification process study of high-level radioactive waste liquids, precipitates present in the simulated waste glasses are detected by X-ray diffraction (XRD), but due to the state of the precipitates (fine size, extremely small amount), precipitate peaks cannot be observed in the XRD pattern. We have evaluated the glass structure of simulated waste glasses prepared under different melting and coagulated conditions using Raman spectroscopy and other methods, in this study. The simulated waste glass, which does not show any precipitate peaks in the XRD pattern, was subjected to Raman spectroscopy, and it was confirmed that precipitate particles in the glass phase could be detected. And it was confirmed that in glass preparation, stirring the molten glass and increasing the cooling rate from the molten state are likely to suppress the formation of precipitate particles in the glass phase. The evaluation of the Si-O bridging structure of the glass revealed no difference in the Si-O bridging structure between areas with and without precipitates. The precipitates detected by Raman spectroscopy are not ceria (CeO) or calcium molybdate (CaMoO), but they are presumed to be compounds such as spinel. In experiments using synchrotron radiation, X-ray transmission images of the internal state of glasses were observed, and it was confirmed that stirring molten glass is effective in reducing bubbles present in the glass phase. The XAFS measurements of Mo K-edge, Ce L-edge, and Si K-edge confirmed that stirring the molten glass does not affect the chemical state of Mo, Ce, and Si contained in the glass.

Structural investigation of borosilicate glasses by using XAFS measurement in soft X-ray region, 4 (Joint research)

Nagai, Takayuki; Okamoto, Yoshihiro; Shibata, Daisuke*; Kojima, Kazuo*; Hasegawa, Takehiko*; Sato, Seiichi*; Fukaya, Akane*; Hatakeyama, Kiyoshi*

JAEA-Research 2024-014, 54 Pages, 2025/02

JAEA-Research-2024-014.pdf:7.02MB

XAFS measurements in the soft X-ray region are suitable for evaluating the chemical state of the surface layer of a measurement sample because the X-ray transmittance is low. In this study, the purpose of the study was to confirm the difference between the coagulated surface layer and the inside of the simulated waste glasses by measuring the K-edge of the glass constituent elements boron, oxygen, sodium, and silicon, and the L edge of the waste component cerium. As a result, the B K-edge XANES spectra showed that the proportion of B-O tetracoordinate sp structures (BO) on the surface layer of the coagulated glass samples was higher than that on the cut surface inside the glass samples, which is expected to improve the water resistance of the coagulated surface. On the other hand, the O K-edge XANES spectra suggested that the O abundance in the coagulated surface layer was lower than that in the cut surface inside the glass samples, and that alkali metal elements may be concentrated in the coagulated surface layer. However, no difference was observed in the Na K-edge XANES spectra between the coagulated surface layer and the cut surface, and no difference was observed in the Si K-edge XANES spectra between the solidified surface and the inside of glass samples. In addition, the Ce L-edge XANES spectra confirmed that the Ce valence in the surface layer of coagulated glass samples were oxidized compared to the inside of glass samples.

Structural investigation of borosilicate glasses by using XAFS measurement in soft X-ray region, 3 (Joint research)

Nagai, Takayuki; Okamoto, Yoshihiro; Yamagishi, Hirona*; Shibata, Daisuke*; Kojima, Kazuo*; Hasegawa, Takehiko*; Sato, Seiichi*; Fukaya, Akane*; Hatakeyama, Kiyoshi*

JAEA-Research 2023-004, 45 Pages, 2023/09

JAEA-Research-2023-004.pdf:6.07MB

The local structure of glass-forming elements and waste elements in borosilicate glasses varies with its chemical composition. In this study, simulated waste glass samples were prepared and the chemical state regarding boron (B), silicon (Si) and waste elements of iron (Fe), cesium (Cs) were estimated by using XAFS measurement in soft X-ray region. To understand the chemical stability of simulated waste glasses, XANES spectra of B K-edge, Fe L, L-edge, and Cs M, M-edge were measured on the glass surface exposed to the leachate. As a result, it was found that the glass surface exposed to the leachate was changed and it was difficult to obtain a clear XANES spectrum. From the B K-edge XANES spectra on glass surfaces exposed to the leachate, an increase in three-coordination of B-O (BO) and a decrease in four-coordination of B-O (BO) were observed compared to the glass surfaces before immersion. The XANES spectra of Fe L, L-edge, and Cs M, M-edge show that as the exposure time in the leachate increases, the Cs present on the glass surface dissolves into the leachate. The XANES spectra of Si K-edge were measured on simulated waste glass surfaces before immersion, and it was confirmed that the change in XANES spectra given by NaO concentration had a larger effect than the waste component concentration.

Studies of high density baryon matter with high intensity heavy-ion beams at J-PARC

Sako, Hiroyuki; Harada, Hiroyuki; Sakaguchi, Takao*; Chujo, Tatsuya*; Esumi, Shinichi*; Gunji, Taku*; Hasegawa, Shoichi; Hwang, S.; Ichikawa, Yudai; Imai, Kenichi; et al.

Nuclear Physics A, 956, p.850 - 853, 2016/12

https://doi.org/10.1016/j.nuclphysa.2016.03.030

Review of research and development of accelerator-driven system in Japan for transmutation of long-lived nuclides

Mukaiyama, Takehiko; Takizuka, Takakazu; Mizumoto, Motoharu; Ikeda, Yujiro; Ogawa, Toru; Hasegawa, Akira; Takada, Hiroshi; Takano, Hideki

Progress in Nuclear Energy, 38(1-2), p.107 - 134, 2001/02

https://doi.org/10.1016/S0149-1970(00)00098-6

no abstracts in English

Basic research programs of vitrification technology for waste volume reduction, 129; Structural investigation of borosilicate glasses by using XAFS measurement in soft X-ray region

Nagai, Takayuki; Okamoto, Yoshihiro; Shibata, Daisuke*; Kojima, Kazuo*; Hasegawa, Takehiko*; Sato, Seiichi*; Fukaya, Akane*; Hatakeyama, Kiyoshi*

no journal, , 

no abstracts in English

Analysis of bystander effect in human lung cancer cell line using high-LET heavy-ion microbeam

Harada, Kosaku*; Nonaka, Tetsuo*; Sakurai, Hideyuki*; Kawamura, Hidemasa*; Hasegawa, Masatoshi*; Nakano, Takashi*; Hamada, Nobuyuki*; Wada, Seiichi*; Kobayashi, Yasuhiko; Funayama, Tomoo; et al.

no journal, , 

no abstracts in English

R&D of lithium target and test facilities for the fusion neutron source

Wakai, Eiichi; Kondo, Hiroo; Kanemura, Takuji; Hirakawa, Yasushi; Furukawa, Tomohiro; Kikuchi, Takayuki; Ito, Yuzuru*; Hoashi, Eiji*; Yoshihashi, Sachiko*; Horiike, Hiroshi*; et al.

no journal, , 

no abstracts in English