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Matsubara, Ryuta*; Ueno, Fuga*; Iwata, Hajime; Inagaki, Yaohiro*; Okubo, Takahiro*
NUMO-TR-24-03, p.55 - 61, 2024/10
no abstracts in English
Matsubara, Ryuta*; Hamamoto, Takafumi*; Ishidera, Takamitsu
NUMO-TR-24-03, p.65 - 70, 2024/10
no abstracts in English
Matsubara, Ryuta*; Takubo, Yusaku*; Iwata, Hajime; Inagaki, Yaohiro*; Okubo, Takahiro*
NUMO-TR-24-01, p.104 - 108, 2024/05
no abstracts in English
Matsubara, Ryuta*; Hamamoto, Takafumi*; Ishidera, Takamitsu
NUMO-TR-24-01, p.91 - 94, 2024/05
no abstracts in English
Matsubara, Ryuta*; Ishida, Keisuke*; Mitsui, Seiichiro; Inagaki, Yaohiro*; Okubo, Takahiro*
NUMO-TR-22-02, p.65 - 67, 2023/03
no abstracts in English
Hamamoto, Takafumi*; Matsubara, Ryuta*; Shibutani, Sanae*; Suyama, Tadahiro*; Tachi, Yukio
JAEA-Data/Code 2017-014, 31 Pages, 2018/03
JAEA-Data-Code-2017-014.pdf:2.1MB
JAEA-Data-Code-2017-014-appendix(CD-ROM).zip:0.61MB
NUMO and JAEA have developed the methodology of post-closure safety assessment for the geological disposal. For this purpose, NUMO and JAEA have conducted a collaborative research project for developing the safety assessment methodology based on international state of the art knowledge. The present report focuses on investigation of sorption and diffusion data reported and their QA evaluation for updating sorption and diffusion database (SDB and DDB) as the collaborative research project between NUMO and JAEA. This report includes sorption and diffusion data for mainly sedimentary rocks and cement materials. As a result, 1,746 sorption data from 19 references and 593 diffusion data from 25 references were extracted and prepared in the datasheet of SDB and DDB.
Matsubara, Ryuta*; Ishida, Keisuke*; Fujisaki, Kiyoshi*; Ishiguro, Katsuhiko*; Inagaki, Yaohiro*; Okubo, Takahiro*; Iwata, Hajime
no journal, ,
In order to improve reliability of performance assessment of vitrified waste for geological disposal, we have been developing a model to predict the long-term glass dissolution under disposal conditions. This presentation provides our R&D plan and the recent progress.
Hamamoto, Takafumi*; Ishidera, Takamitsu; Matsubara, Ryuta*
no journal, ,
no abstracts in English
Matsubara, Ryuta*; Ishiguro, Katsuhiko*; Ishida, Keisuke*; Inagaki, Yaohiro*; Okubo, Takahiro*; Iwata, Hajime
no journal, ,
Goto, Takahiro*; Matsubara, Ryuta*; Hamamoto, Takafumi*; Fujisaki, Kiyoshi*; Mitsui, Seiichiro; Taniguchi, Naoki
no journal, ,
For the purpose of improvement of long-term glass corrosion model, we conducted immersion tests with specimens of carbon steel and simulated waste glass at 50
C and 80C under nitrogen gas atmosphere. We also conducted control immersion tests with a specimen of carbon steel or simulated waste glass under the same conditions. After the immersion tests, we determined glass corrosion rates and secondary phases on the surface of carbon steel specimen. Glass corrosion rates for the immersion tests with specimens of carbon steel and simulated waste glass were three times larger than those for the control immersion tests with simulated waste glass specimen. With X-ray diffraction, several peaks associated with an iron silicate mineral were identified. This observation is consistent with the results of geochemical calculation based on solution data and published study using carbon steel and simulated waste glass.
Goto, Takahiro*; Matsubara, Ryuta*; Hamamoto, Takafumi*; Fujisaki, Kiyoshi*; Mitsui, Seiichiro; Taniguchi, Naoki
no journal, ,
To improve long-term glass corrosion model, immersion tests with specimens of carbon steel and simulated waste glass were conducted at 50C and 80C under nitrogen gas atmosphere for 131 days. Control tests with a specimen of carbon steel or glass under the same conditions were also conducted. After the tests, the element concentration in the solution was analyzed to determine glass corrosion rates. We also analyzed the surface of specimens with XRD and TEM/ED (electron diffraction)/EDX to identify secondary phases. Glass corrosion rates for the tests with specimens of carbon steel and glass were two times larger than those for the control tests with glass specimen. With XRD and TEM/ED/EDX, we determined iron silicates on the surface of both carbon steel and glass. These observations are consistent with the results of geochemical calculation and published studies. The results indicate that glass corrosion could be enhanced by the precipitation of iron silicates.
Matsubara, Ryuta*; Fujisaki, Kiyoshi*; Ishida, Keisuke*; Ishiguro, Katsuhiko*; Inagaki, Yaohiro*; Okubo, Takahiro*; Mitsui, Seiichiro; Iwata, Hajime; Sekine, Nobuyuki*
no journal, ,
Restriction of radionuclide release by low dissolution rate is expected for the vitrified waste as a one of safety functions of the geological disposal system. In order to assess the performance of vitrified waste, it is important to understand how its safety function works under the environmental condition of a deep geological repository. This presentation provides the recent progress on the R&D to improve the current understanding of the key processes affecting glass dissolution rate and the predictive modeling of long-term behavior of the vitrified waste.
Matsubara, Ryuta*; Fujisaki, Kiyoshi*; Ishida, Keisuke*; Ishiguro, Katsuhiko*; Inagaki, Yaohiro*; Okubo, Takahiro*; Mitsui, Seiichiro; Iwata, Hajime; Sekine, Nobuyuki*
no journal, ,
Since the performance of vitrified High-level Radioactive Waste depends on thermal, hydraulic, mechanical, and chemical (THMC) conditions, NUMO, as the implementer of geological disposal, has been promoting R&D of operational model the long-term performance of vitrified High-level Radioactive Waste in consideration of THMC conditions. NUMO has identified R&D issues regarding the glass dissolution and planed the R&D program through FEP (Features, Events, and Processes) analysis and parametric study with numerical model to evaluate relative importance of relevant processes. At present, three R&D programs are ongoing as joint researches with JAEA and two universities: long term glass dissolution experiment to understand evolution of glass dissolution kinetics, glass dissolution experiment at various environmental conditions to assess the performance under several potential repository conditions with the time evolution, and molecular dynamics simulation to understand elemental migration at the interface between glass surface and groundwater. The current status of R&D programs will be introduced in this presentation.
