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Sone, Tomoyuki; Sasaki, Toshiki; Yamaguchi, Hiromi
Proceedings of 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '07) (CD-ROM), 5 Pages, 2007/00
We have stored waste TBP/dodecane generated from R&D activities on recycle of nuclear fuel. Those wastes can be incinerated, however a large quantity of contaminated phosphorous compounds generate. The objective of this study is to reduce the generation of radioactive secondary waste by the treatment of those wastes using steam reforming system. We conducted process demonstration tests using waste TBP/dodecane with 0.07g/L of uranium. We studied the temperature dependence of the gasification ratio of inorganic phosphorus compounds and removal of uranium by the filter. As the results, more than 95% of phosphorus compounds were gasified at temperature of 600
C or more, and more than 98% of uranium compounds were separated from the vaporized waste. The separated phosphorus compounds can be disposed of as the liquid wastes of which concentration of uranium is under the regulatory level. These results show the steam reforming system is effective in the reduction of radioactive secondary waste in the treatment of TBP/dodecane.
Takeuchi, Shinji; Takeuchi, Ryuji; Salden, W.*; Saegusa, Hiromitsu; Arai, Takashi*; Matsuki, Koji*
Proceedings of 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '07) (CD-ROM), 8 Pages, 2007/00
A hydrogeological conceptual model has been developed based on pressure responses observed at multilevel pressure monitoring zones in seven boreholes and surface tilt data in and around the Mizunami Underground Research Laboratory site. Pressure changes caused by some earthquakes, cross-hole hydraulic testing, and shaft excavation activities are considered. Surface tilt has been measured from the half way of the shaft excavation phase. Continuous monitoring with some numerical analysis during the shaft excavation phase show the existence of the flow barrier fault predicted from the surface-based investigation phase and hydraulic parameter around the shafts.
Saegusa, Hiromitsu; Onoe, Hironori; Takeuchi, Shinji; Takeuchi, Ryuji; Oyama, Takuya
Proceedings of 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '07) (CD-ROM), 8 Pages, 2007/00
The Mizunami Underground Research Laboratory (MIU) project is planned for broad scientific study of the deep geological environment as a basis of research and development for geological disposal of nuclear wastes. One of the main goals of the project is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological environment. Hydrogeological investigations using a stepwise process in Surface-based Investigation Phase have been carried out in order to obtain information on important properties. Hydrogeological modeling and groundwater flow simulations have been carried out in order to synthesize the investigation results, to evaluate the uncertainty of the model and to identify the main issues for further investigations. Using the stepwise hydrogeological characterization approach and combining the investigation with modeling and simulation, understanding of the hydrogeological environment has been progressively improved.
Guimer
, J.*; Ruiz, E.*; Luna, M.*; Arcos, D.*; Dom
nech, C.*; Jordana, S.*; Saegusa, Hiromitsu; Iwatsuki, Teruki
Proceedings of 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '07) (CD-ROM), 8 Pages, 2007/00
Many possible origins have been proposed for the saline groundwater observed in granite show total dissolved solids increasing to 50 mmol/L at depths below 800 m. Different hypothesis have been formulated to explain the observed fluid composition, among them, long-term water-rock interaction, mixing with residual fluids of magmatic origin and relict seawater dating from Miocene times. A review of the hydrochemical and isotopic data suggest that the three above hypotheses may be valid, at least to different degrees, or that processes acting over more recent geological times may be involved. The origin of the salinity was assessed by simulating land emersion by means of changing the upper recharge boundary. In this manner the Miocene seawater was modelled as being continually mixed with fresh water until the present time. The effects of different retardation processes were considered by varying factors such as matrix diffusion and fracture conductivity. Finally, geochemical reactions reproduced trends in major ions and master variables.
