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M
ri, A.*; Mazurek, M.*; Ota, Kunio; Siitari-Kauppi, M.*; Eichinger, F.*; Leuenberger, M.*
Minerals (Internet), 11(10), p.1072_1 - 1072_17, 2021/10
Times Cited Count：4 Percentile：34.69(Geochemistry & Geophysics)Tachi, Yukio; Ito, Tsuyoshi*; Akagi, Yosuke*; Sato, Hisao*; Martin, A. J.*
Water Resources Research, 54(11), p.9287 - 9305, 2018/11
Times Cited Count：5 Percentile：26.57(Environmental Sciences)Effects of fine-scale surface alterations on radionuclide migration in fractured crystalline rocks were investigated by a comprehensive approach coupling a series of laboratory tests, microscopic observations and modelling, using a single fractured granodiorite sample from the Grimsel Test Site, Switzerland. Laboratory tests including through-diffusion, batch sorption and flow-through tests using five tracers indicated that tracer retention was consistently in the sequence of HDO, Se, Cs, Ni, Eu, and as well as showing the existence of a diffusion-resistance layer near the fracture surface, cation excess and anion exclusion effects for diffusion. Microscale heterogeneities in structural properties around the fracture were clarified quantitatively by coupling X-ray CT and EPMA. A three layer model including weathered vermiculite, foliated mica and undisturbed matrix layers, and their properties such as porosity, sorption and diffusion parameters, could provide a reasonable interpretation for breakthrough curves and concentration distributions near fracture surface of all tracers, measured in flow-through tests.
Soler, J. M.*; Landa, J.*; Havlov
, V.*; Tachi, Yukio; Ebina, Takanori*; Sardini, P.*; Siitari-Kauppi, M.*; Eikenberg, J.*; Martin, A. J.*
Journal of Contaminant Hydrology, 179, p.89 - 101, 2015/08
Times Cited Count：39 Percentile：81.5(Environmental Sciences)Matrix diffusion is a key process for radionuclide retention in crystalline rocks. An in-situ diffusion experiment in granite matrix was performed at the Grimsel Test Site (Switzerland). Several tracers (HTO, Na
, Cs) were circulated through a borehole and the decrease in tracer concentrations was monitored for 2.5 years. Then, the borehole section was overcored and the tracer profiles in the rock were analyzed. Transport distances in the rock were 20 cm for HTO, 10 cm for Na and 1 cm for Cs. The dataset was analyzed with diffusion-sorption models by different teams using different codes, with the goal of obtaining effective diffusivities (De) and rock capacity factors. There was a rather good agreement between the values from different teams, implied that De and capacity factors in the borehole damaged zone are larger than those in the bulk rock. However, HTO seems to display large discrepancies between measured and modeled results.
Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo
JAERI-Tech 2005-043, 27 Pages, 2005/08
JAERI-Tech-2005-043.pdf:2.51MB
Multi-step resonance ionization spectrometry for long-lived nuclei in nuclear waste materials requires laser sources having high frequency stability and tunability. In this study we have developed a novel frequency control system consisting of digital circuitry and computer to improve the frequency tunability of the developed laser stabilization system using dichroic atomic vapor laser lock (DAVLL) and fringe offset lock (FOL) techniques. Based on the heterodyne experiment and multi-step laser induced fluorescence spectroscopy of atomic Ca, the frequency stability and tunability of the developed system were evaluated.
Ca ionization potential by high-precision three-step resonance ionization spectroscopyMiyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo
JAERI-Research 2004-023, 17 Pages, 2004/11
JAERI-Research-2004-023.pdf:2.71MB
High precision resonance ionization spectroscopy has been applied to determination of an accurate ionization potential of Ca. Three-step resonant excitation with single-mode extended cavity diode lasers populates a series of 
(
P
) and 
(F
) Rydberg states in the rage of 
=20-150. By using an extended Ritz formula for quantum defect, the series convergence limit has been determined to be 49305.9240 (20) cm
with the accuracy improved one order of magnitude higher than previously reported ones.
Iguchi, Tetsuo; Watanabe, Kenichi*; *; Nose, Shoichi; Harano, Hideki;
JNC TY9400 2000-019, 34 Pages, 2000/05
JNC-TY9400-2000-019.pdf:0.79MB
None
Miyabe, Masabumi; Oba, Masaki; Wakaida, Ikuo
JAERI-Research 97-078, 28 Pages, 1997/10
JAERI-Research-97-078.pdf:0.9MB
no abstracts in English
Miyabe, Masabumi; Wakaida, Ikuo; Akaoka, Katsuaki; Oba, Masaki; Arisawa, Takashi
Laser Advanced Materials Processing,Vol. 2, p.1239 - 1243, 1992/06
no abstracts in English
Miyabe, Masabumi; Wakaida, Ikuo; Akaoka, Katsuaki; Oba, Masaki; Arisawa, Takashi
Resonance Ionization Spectroscopy 1992 (Institute of Physics Conf. Series Number 128), 0, p.139 - 142, 1992/00
no abstracts in English
Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Wakaida, Ikuo; Hasegawa, Shuichi*
no journal, ,
Because of environmental pollution of the radioactive materials released from TEPCO's Fukushima Daiichi Nuclear Power Station, considerable attention has been focused on food safety in Japan. Whereas the principal pollutants for foods are radioactive 
Cs and 
Cs, the radioactive 
Sr, one of the alkaline earth elements like Ca and its radiation can damage bone marrow, is also one of the most important nuclide considering the possible occurrence of biological concentration through food chain. This Sr is the pure 
-ray emitter of which energy is 0.546 MeV (28.78 years) and is known as the nuclide for which analysis is difficult. For radiometric analysis, to eliminate various emitters which potentially interfere the Sr analysis, not only a repeated application of ion-exchange and coagulating sedimentation processes but also a period of longer than 2 weeks are needed to establish radioactive equilibrium between Sr and its daughter nuclide Y. To realize a prompt Sr analysis for marine foods, we are developing a new analytical technique by combining resonance ionization spectroscopy (RIS) and ion trap detection. In the present study, we have evaluated ionization efficiency and analytical performances using highly efficient and isotope-selective RIS scheme which we determined in our previous study.
Soler, J. M.*; Martin, A. J.*; Lanyon, G. W.*; Havlov, V.*; Siitari-Kauppi, M.*; Tachi, Yukio
no journal, ,
An in-situ long-term diffusion (LTD) project has been performed at the Grimsel Test Site, Switzerland, to realistically evaluate matrix diffusion of radionuclides in crystalline rock with minimal disturbance to in-situ conditions. A second in situ diffusion experiment (monopole 2) has been performed. Predictive calculations for the monopole-2 experiment, based on results from monopole 1 or from through-diffusion experiments have been compared to monitoring data from the injection and observation boreholes. For the non-sorbing tracers (HTO, 
Cl
), the diffusion parameters from the through-diffusion experiments provide a better match for the measurements, especially in the injection borehole. The initial drop in activities for 
Cs and 
Ba
shows clearly the effect of sorption. Bulk rock parameters for Cs from monopole 1 seem to be applicable to monopole 2. However, Ba seems to sorb more strongly than expected.
Tachi, Yukio; Ito, Tsuyoshi; Akagi, Yosuke*; Sato, Hisao*; Martin, A. J.*
no journal, ,
The effects of heterogeneity at fracture surface on radionuclides migration in fractured crystalline rocks was investigated by laboratory migration experiments, microscopic observations and detailed modelling, using a single fractured granodiorite sample from the Grimsel Test Site (GTS), Switzerland. The tracer migration behaviors in fracture and matrix parts were evaluated by series of laboratory experiments including through-diffusion and flow-through experiments. Mineral distributions from fracture surface to matrix were evaluated by X-ray CT, and were validated by comparing the elemental mapping measured by EPMA. Based on the microscopic observations by X-ray CT and EPMA, the aperture and connectivity in fracture and minerals distribution near fracture surface were quantitatively evaluated. The heterogeneous multi-layered model assuming a weathered vermiculite zone, a foliated mica zone and rock matrix was possible to provide a reasonable interpretation for measured breakthrough curves of all tracers.
Tachi, Yukio; Ito, Tsuyoshi*; Fukatsu, Yuta; Akagi, Yosuke*; Sato, Hisao*; Hu, Q.*; Martin, A. J.*
no journal, ,
