Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Kazuya Idemitsu Last modified date:2019.07.16

Professor / Laboratory of Energy Materials Science / Department of Applied Quantum Physics and Nuclear Engineering / Faculty of Engineering


Presentations
1. @Kazuya Idemitsu, #Ryota Yamada, #Masayuki Hirakawa, #Yuki Kakoi, #Hajime Arimitsu, @Yaohiro Inagaki, @Tatsumi Arima, Effect of Carbonate on the Migration Behavior of Strontium in Compacted Bentonite, Scientific Basis for Nuclear Waste Management 2018, 2018.11.
2. @Kazuya Idemitsu, #Yuki Kakoi, #Hajime Arimitsu, @Yaohiro Inagaki, @Tatsumi Arima, Ultra-trace level measurement of neptunium in bentonite by using ICP-QQQ, International Conference on Ceramic Materials and Components for Energy and Environmental Applications (CMCEE-12), 2018.07.
3. Kazuya Idemitsu, Kazuyuki Fujii, Noriyuki Maeda, Yuki Kakoi, Noriya Okubo, Yaohiro Inagaki, Tatsumi Arima, Effect of Carbonate on the Migration Behavior of Lanthanides in Compacted Bentonite, Scientific Basis for Nuclear Waste Management 2017, 2017.11.
4. Kazuya Idemitsu, Noriya Okubo, Yaohiro Inagaki, Tatsumi Arima, Daisuke Akiyama, Kenji Konashi, Makoto Watanabe, Plutonium Migration in Compacted Bentonite with Iron Corrosion for 15 Years, Scientific Basis for Nuclear Waste Management XL, 2016.11.
5. Kazuya Idemitsu, Ryo Hamada, Yoshitaka Ogawa, Noriya Okubo, Yaohiro Inagaki, Tatsumi Arima, Salinity Dependence of Apparent Diffusion Coefficients of Selenite, Selenate, Molybdate and Iodate in Compacted Bentonite, Goldschmidt2016, 2016.06.
6. Yaohiro Inagaki, Ryo Matsumoto, Kazuya Idemitsu, Tatsumi Arima, Dissolution Kinetics of a Simplified Nuclear waste Glass, ISG, in MgCl2 Solution, Goldschmidt2016, 2016.06.
7. Ryo Hamada, Noriyuki Maeda, Kazuya Idemitsu, Yaohiro Inagaki, Tatsumi Arima, Daisuke Akiyama, Kenji Konashi, Makoto Watanabe, Shinichi Koyama, Effect of pH on Plutonium Migration Behavior in Compacted Bentonite, Scientific Basis for Nuclear Waste Management XXXIX, 2015.10.
8. Kazuya Idemitsu, Tomofumi Sakuragi, Immobilization Techniques for Geological Disposal of Radioactive Iodine in Japan, American Ceramics Society MS&T'15, 2015.10.
9. Kazuya Idemitsu, Tomofumi Sakuragi, Current Status of Immobilization Techniques for Geological Disposal of Radioactive Iodine in Japan, Scientific Basis for Nuclear Waste Management XXXVIII, 2014.12.
10. Ryou Kimura, Yaohiro Inagaki, Kazuya Idemitsu, Tatsumi Arima, Vitrification Processes of Simulated Cesium Sorbing Zeolite Waste, Scientific Basis for Nuclear Fuel Cycle II, 2014.08.
11. Noriyuki Maeda, Kazuya Idemitsu, Yusuke Irie, Daisuke Akiyama, Hikaru Kozaki, Tatsumi Arima, Yaohiro Inagaki, Migration Behavior of Cesium Molybdate in Compacted Bentonite, Scientific Basis for Nuclear Fuel Cycle II, 2014.08.
12. Kazuya Idemitsu, Hikaru Kozaki, Masaru Yuhara, Tatsumi Arima, Yaohiro Inagaki, Migration Behavior of Selenite in Compacted Bentonite, Scientific Basis for Nuclear Fuel Cycle II, 2014.08.
13. Tatsumi Arima, Kazuya Idemitsu, Yaohiro Inagaki, Katsuyuki Kawamjra, Yukio Tachi, Kenji Yotsuji, Diffusion and Adsorption of Uranyl ion in Clays: Molecular Dynamics Study, Scientific Basis for Nuclear Fuel Cycle II, 2014.08.
14. Daisuke Akiyama, Kazuya Idemitsu, Yaohiro Inagaki, Tatsumi Arima, Kenji Konashi, Shinichi Koyama, Migration behavior of plutonium affected by ferrous ion in compacted bentonite by using electrochemical technique, Scientific Basis for Nuclear Waste Management XXXV, 2013.10.
15. Kazuya Idemitsu, Hikaru Kozaki, Daisuke Akiyama, Masanao Kishimoto, Masaru Yuhara, Noriyuki Maeda, Yaohiro Inagaki, tatsumi arima, Migration Behavior of Selenium in the Presence of Iron in Bentonite, Scientific Basis for Nuclear Waste Management XXXV, 2013.10, Selenium (Se) is an important element for assessing the safety of high-level waste disposal. Se is redox-sensitive, and its oxidation state varies from -2 to 6 depending on the redox conditions and pH of the solution. Large quantities of ferrous ions formed in bentonite due to corrosion of carbon steel overpack after the closure of a repository are expected to maintain a reducing environment near the repository. Therefore, the migration behavior of Se in the presence of Fe in bentonite was investigated by electrochemical experiments. Na2SeO3 solution was used as tracer solution. Dry density range of bentonite was from 0.8 to 1.4 ×103 kg/m3.
Results indicated that Se was strongly retained by the processes such as precipitation reaction with ferrous ions in bentonite. Se K-edge X-ray absorption near-edge structure (XANES) measurements were performed at the BL-11 beamline at SAGA Light Source, and the results revealed that the oxidation state of Se in the bentonite remained Se(IV)..
16. Kazuya Idemitsu, Yaohiro Inagaki, Tatsumi Arima, Daisuke Akiyama, Yusuke Irie, Hikaru Kozaki, Migration Behavior of Cesium Molybdate in Compacted Bentonite, Materials Research Society 2012, 2012.11.
17. Study on the pH of the Pore Water in Compacted Bentonite under Reducing Environment..
18. Migration behavior of plutonium in bentonite under electric gradient.
19. Migration behavior of cesium in compacted bentonite using electromigration.
20. Corrosion Products of Carbon Steel formed in Compacted Bentonite.
21. Establishment of a method to identify degraded thin regions between cement and bentonite (2).
22. Migration behavior of plutonium in buffer material using carbon steel anode method.
23. Establishment of a method to identify degraded thin regions between cement and bentonite.
24. The distribution coefficient:Definition and necessity of standerdization.
25. Migration behavior of iron in buffer material using carbon steel anode method(III).
26. Mechanism of P0798 glass corrosion in alkaline solution and associated Cs release.
27. Carbon steel is one of the candidate overpack materials for high-level waste disposal and is expected to assure complete containment of vitrified waste glass during an initial period of 1000 years in Japan. Carbon steel overpack will be corroded by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. The reducing condition will be expected to retard the migration of redox-sensitive radionuclides by lowering their solubilities. Therefore, the presence of corrosion products of iron in buffer material is important to discuss the migration behavior of redox-sensitive radionuclides. Plutonium electromigration experiments in bentonite have been carried out with source of iron ions supplied by anode corrosion of iron coupon. Plutonium migrated from the iron anode toward cathode as deep as 1 mm of the interior of bentonite within 24 h. Thus plutonium chemical species would have positive charge and were estimated as PuOH2+ or PuCl2+ by the thermodynamic calculation..
28. Fundamental study on P0798 HLW glass corrosion and mineralization.
29. Migration behavior of iron in buffer material using carbon steel anode method(II).
30. Carbon steel is one of the candidate overpack materials for high-level waste disposal and is expected to assure complete containment of vitrified waste glass during an initial period of 1000 years in Japan. The lifetime of the carbon steel overpack will depend on its corrosion rate. The corrosion rate of carbon steel is reduced by the presence of buffer material such as bentonite. Buffer material will delay the supply of corrosive materials and discharge of corrosion products through it. Carbon steel overpack will be corroded by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. The reducing condition will be expected to retard the migration of redox-sensitive radionuclides by lowering their solubilities. Therefore, the diffusion of corrosion products of iron in buffer material is important to discuss the corrosion rate of overpack, properties of buffer material and migration of redox-sensitive radionuclides. Electromigration experiments have been carried out with source of iron ions supplied by anode corrosion of iron coupon. Iron ions migrated as fast as 2mm in 2 or 3 hours under electrical field of 100V/m to the direction of cathode. Because the iron ions displaced exchangeable sodium ions in bentonite at a ratio of 1 to 2 during the electromigration, migrating iron ion could be ferrous ion..
31. Migration behavior of iron in buffer material using carbon steel anode method.
32. iodine release from silver iodine under reducing conditions with iron-bearing minerals.
33. Carbon steel is one of the candidate overpack materials for high-level waste disposal and is expected to assure complete containment of vitrified waste glass during an initial period of 1000 years in Japan. The lifetime of the carbon steel overpack will depend on its corrosion rate. The corrosion rate of carbon steel is reduced by the presence of buffer material such as bentonite. Buffer material will delay the supply of corrosive materials and discharge of corrosion products through it. Carbon steel overpack will be corroded by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. The reducing condition will be expected to retard the migration of redox-sensitive radionuclides by lowering their solubilities. Therefore, the diffusion of corrosion products of iron in buffer material is important to discuss the corrosion rate of overpack, migration of redox-sensitive radionuclides and properties of buffer material. The purpose of this paper is to study diffusion behavior of a corrosion product of iron in compacted bentonites under a reducing condition with a carbon steel. The diffusion mechanism of iron in the compacted bentonites were discussed by estimation of iron species in the bentonite pore water. There were two diffusion paths of iron in the compacted bentonites used in this study ; the fast path has low capacity of iron, ca. 1wt%, and large apparent diffusion coefficient, ca. 10-12 m2/s and the slow path has high capacity of iron, ca. 10wt%, and small apparent diffusion coefficient, ca. 10-14 m2/s..
34. The apparent diffusion coefficients and distribution coefficients of Cs and Sr in compacted bentonites have been determined by in-diffusion method combined with penetration profile method. A compacted bentonite was contacted with tracer solution which contains 134Cs and 85Sr as tracers and 100, 10, 1 or 0.1 mmol dm-3 of NaCl for a week at room temperature. The apparent diffusion coefficients of Cs and Sr were estimated from the concentration profile. The intercept of a concentration profile divided by the concentration of the tracer in solution gives the distribution coefficients. The apparent diffusion coefficients of Cs and Sr decreased with increasing dry density, however, were not affected by ionic strength of contacting solutions. The distribution coefficients of Sr were around 10 kg dm-3 and not affected by ionic strength of contacting solutions, however, the distribution coefficients of Cs were around 40 kg dm-3 and slightly decreased with increasing the ionic strength. The apparent diffusion coefficient of Cs and Sr obtained in this study was not a function of distribution coefficient, such as a reciprocal function. Estimated effective diffusion coefficients of Cs and Sr were around 10-10m2 s-1 and were comparable with effective diffusion coefficients of 3H. These results suggest that surface diffusion occurs in compacted bentonite for Cs and Sr..
35. Effects of ion strength on diffusion of Cs and Sr.
36. Effects of crystal form and redox condition on solubility of silver iodine.
37. Surface diffusion at water-mineral interfaces for geologic disposal(1)
Literature survey on contribution of surface diffusion.
38. Fundamental study on HLW glass corrosion and mineralizaion.
39. Diffusion behavior of Cs and Sr in polycrystal beta"-alumina.