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 change by phosphorus addition to borosilicate glass containing simulated waste components

Okamoto, Yoshihiro; Shiwaku, Hideaki; Shimamura, Keisuke*; Kobayashi, Hidekazu; Nagai, Takayuki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*

Journal of Nuclear Materials, 570, p.153962_1 - 153962_13, 2022/11

https://doi.org/10.1016/j.jnucmat.2022.153962

Simulated nuclear waste glass samples containing phosphorus, which increase the solubility of molybdenum, were prepared and analyzed using synchrotron X-ray Absorption Fine Structure (XAFS) analysis for some constituent elements and Raman spectroscopic analysis of their complex structure. Changes in local structure and chemical state due to different phosphorus additions and waste loading rates were systematically studied. Consequently, no crystalline phase due to the molybdate compound was observed even at a maximum waste content of 30 wt% (corresponding to 1.87 mol% MoO). Oxidation proceeded when the waste-loading rate was increased, whereas the reduction proceeded when phosphorus was added. In some cases, the effects of oxidation and reduction were offset. The local structure around specific elements can be classified as follows; Zn that is affected mainly by the waste-loading rate, Ce that is affected by both the waste-loading rate and phosphorus addition, and Zr element that is not affected by either of them. From the comparison between the analytical results of Mo and other elements, it was considered that the added phosphorus exists as a free PO structural unit and may deprive the alkali metal coordinated to the molybdate ion.

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

Nagai, Takayuki; Okamoto, Yoshihiro; Yamagishi, Hirona*; Ota, Toshiaki*; Kojima, Kazuo*; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*

JAEA-Research 2021-010, 62 Pages, 2022/01

JAEA-Research-2021-010.pdf:6.05MB

The local structure of glass-forming elements and waste elements in borosilicate glasses varies with its chemical composition. In this study, borosilicate glass frit and simulated waste glass samples were prepared and the local structure and chemical state regarding boron(B), oxygen(O), silicon(Si) and waste elements of iron(Fe), cesium(Cs) were estimated by using XAFS measurement in soft X-ray region. Following results were obtained by XAFS measurements of prepared glass frit and simulated waste glass samples: (1) The effect of NaO concentration on B-O coordination structure is greater than that of the waste elements concentration. (2) The height of pre-edge by O K-edge spectrum depends on the concentration of first transition elements such as Fe in glass samples. Following results were obtained by XAFS measurements of simulated waste glass samples after immersion test to investigate the long chemical stability. (1) A new compound was formed on the sample surface after the immersion test, and changes in the surface state were confirmed by Raman spectroscopy. (2) Cs on the sample surface after immersion test dissolves into the leaching solution. The Si K-edge XANES spectra of borosilicate glass frits and simulated waste glass samples included lanthanides oxide were measured, and following was confirmed. (1) As the NaO concentration increases in borosilicate glass frit, the K-edge peak of Si shifts to the low energy side. (2) The peak height of the K-edge of Si differs depending on the kind of lanthanide.

Structural investigation of simulated waste glass samples by using XAFS measurement in soft X-ray region (Joint research)

Nagai, Takayuki; Okamoto, Yoshihiro; Yamagishi, Hirona*; Ota, Toshiaki*; Kojima, Kazuo*; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*

JAEA-Research 2020-009, 48 Pages, 2020/09

JAEA-Research-2020-009.pdf:4.53MB

The local structure of glass-forming elements and waste elements in waste glass varies with its chemical composition. In this study, borosilicate glass frit and simulated waste glass samples were prepared and the local structure and chemical state regarding boron (B), oxygen (O), and waste elements of cerium (Ce), cesium (Cs) were estimated by using XAFS measurement in soft X-ray region. Following results were obtained by XAFS measurements of prepared glass frit and simulated waste glass samples: (1) The existence ratio of four coordinate sp structure (BO) tends to increase with increasing NaO content in glass samples. (2) The height of a pre-edge which appears by K-edge XANES spectrum of O is so high that the Fe content in glass samples. Following results were obtained by XAFS measurements of simulated waste glass samples after immersion test to investigate long chemical stability. (1) The existence ratio of four coordinate sp structure (BO) increases by immersion test. (2) Ce which exists in the surface layer is oxidized by immersion test, and much of Cs in surface layer is lost after leach testing. Even if the glass frit form (fiber cartridge or beads) and manufacturing method were changed and a glass sample of the similar chemical composition was prepared, these observed Raman spectra of samples were different.

Investigation of simulated waste glass samples prepared from borosilicate glass frit including vanadium

Nagai, Takayuki; Okamoto, Yoshihiro; Shiwaku, Hideaki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Hirono, Kazuya*; Homma, Masanobu*; Kobayashi, Hiromi*; Takahashi, Tomoe*; et al.

JAEA-Research 2018-007, 87 Pages, 2018/11

JAEA-Research-2018-007.pdf:61.21MB

To select the chemical composition of a glass frit which can increase the waste content, the simulated waste glass samples prepared from a borosilicate glass frit including vanadium (V) were investigated by using Laser Ablation (LA) ICP-AES analysis, Raman spectrometry, and synchrotron XAFS measurement in this study on foundation business of the Agency for Natural Resources and Energy.

Characterization of non-magnetic Mn-Cr steel as a low induced activation material for vacuum vessels

Saito, Shigeru; Fukaya, Kiyoshi; Ishiyama, Shintaro; Eto, Motokuni; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*; Kikuchi, Mitsuru

Journal of Nuclear Materials, 283-287(Part1), p.593 - 596, 2000/12

https://doi.org/10.1016/S0022-3115(00)00088-X

no abstracts in English

R&D of low activated Fe-Mn-Cr high strength non-magnetic steel, 1; Screening test for constituent optimization and fundamental characterization test

Ishiyama, Shintaro; Fukaya, Kiyoshi; Eto, Motokuni; Kikuchi, Mitsuru; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*

Nihon Genshiryoku Gakkai-Shi, 42(2), p.116 - 123, 2000/02

https://doi.org/10.3327/jaesj.42.116

no abstracts in English

Imaging XAFS analysis of simulated radioactive waste glass by bottom drain test

Okamoto, Yoshihiro; Nagai, Takayuki; Shiwaku, Hideaki; Seki, Katsumi*; Kobayashi, Hiromi*; Homma, Masanobu*; Hatakeyama, Kiyoshi*

no journal, , 

The chemical state of simulated radioactive waste glass prepared by bottom drain tests was investigated by XAFS and imaging XAFS analyses. Gas bubbling operation at melting was added in the test. The XAFS measurements of Cr, Mn, Fe and Ce were performed to evaluate redox (reduction and oxidation) state in the simulated glass. Behavior of platinum group elements in the simulated glass was observed from the imaging XAFS analysis. The XAFS analysis suggested redox state of the glass changed depending on the waste content and the gas bubbling. The imaging XAFS analysis showed that aggregation of platinum group element was reduced by the gas bubbling.

Redox behavior of RuO particles in borosilicate glass melts

Nagai, Takayuki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Seki, Katsumi*

no journal, , 

no abstracts in English

Investigation of the chemical form of ruthenium compounds in the vitrification process, 4; RuO generation by reaction with Ru-La-Na mix nitrates and raw materials for vitrification

Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Sato, Nobuaki*; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Seki, Katsumi*

no journal, , 

It is thought that a generated ruthenium compound grows from a high level radioactive liquid waste into RuO crystal by reacting to raw materials for the vitrification process. In this study, the generation reaction to RuO was confirmed by heating Ru-La-Na mix nitrates and the raw materials.