Refine your search:     
Report No.
 - 
Search Results: Records 1-13 displayed on this page of 13
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Quantifying the porosity of crystalline rocks by in situ and laboratory injection methods

M$"o$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:2 Percentile:65.14(Geochemistry & Geophysics)

Journal Articles

Effects of fine-scale surface alterations on tracer retention in a fractured crystalline rock from the Grimsel Test Site

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:37.45(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.

Journal Articles

Comparative modeling of an in situ diffusion experiment in granite at the Grimsel Test Site

Soler, J. M.*; Landa, J.*; Havlov$'a$, 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:33 Percentile:83.7(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.

JAEA Reports

Development of frequency stabilized laser system for long-lived isotope analysis, 3; Computer-based laser frequency tuning system

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.

JAEA Reports

Determination of the $$^{40}$$Ca ionization potential by high-precision three-step resonance ionization spectroscopy

Miyabe, 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 $$^{40}$$Ca. Three-step resonant excitation with single-mode extended cavity diode lasers populates a series of ${it 4snp}$ ($$^{1}$$P$$_{1}$$) and ${it 4snf}$ ($$^{1}$$F$$_{3}$$) Rydberg states in the rage of ${it n}$=20-150. By using an extended Ritz formula for quantum defect, the series convergence limit has been determined to be 49305.9240 (20) cm$$^{-1}$$ with the accuracy improved one order of magnitude higher than previously reported ones.

JAEA Reports

None

Iguchi, Tetsuo; Watanabe, Kenichi*; *; Nose, Shoichi; Harano, Hideki;

JNC TY9400 2000-019, 34 Pages, 2000/05

JNC-TY9400-2000-019.pdf:0.79MB

None

JAEA Reports

Determination of ionization potential of atomic gadolinium and its isotopes effects; Analysis of unperturbed rydberg series

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

Journal Articles

Characterization of multistep photoionization sequence

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

Journal Articles

Simplified method for estimating multistep photoionization efficiency

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

Oral presentation

Development of resonance ionization mass spectrometry of Sr isotopes, 2

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 $$^{135}$$Cs and $$^{137}$$Cs, the radioactive $$^{90}$$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 $$^{90}$$Sr is the pure $$beta$$-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 $$beta$$ emitters which potentially interfere the $$^{90}$$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 $$^{90}$$Sr and its daughter nuclide $$^{90}$$Y. To realize a prompt $$^{90}$$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.

Oral presentation

The GTS-LTD MONOPOLE-2 experiment at grimsel; Predictive modeling and comparison with monitoring data

Soler, J. M.*; Martin, A. J.*; Lanyon, G. W.*; Havlov$'a$, 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, $$^{36}$$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 $$^{134}$$Cs$$^{+}$$ and $$^{133}$$Ba$$^{2+}$$ shows clearly the effect of sorption. Bulk rock parameters for $$^{134}$$Cs$$^{+}$$ from monopole 1 seem to be applicable to monopole 2. However, $$^{133}$$Ba$$^{2+}$$ seems to sorb more strongly than expected.

Oral presentation

Effects of heterogeneity at fracture surface for tracer migration in a fractured crystalline rock from the Grimsel Test Site

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.

Oral presentation

Realistic modeling approach for tracer migration and retention in fractured crystalline rocks from the Grimsel Test Site

Tachi, Yukio; Ito, Tsuyoshi*; Fukatsu, Yuta; Akagi, Yosuke*; Sato, Hisao*; Hu, Q.*; Martin, A. J.*

no journal, , 

13 (Records 1-13 displayed on this page)
  • 1