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Matsumoto, Kazuhiro*; Tanai, Kenji; Kanno, Takeshi*; Iwata, Yumiko*
JNC TN8400 2005-009, 40 Pages, 2005/06
The buffer that will be used as a component of the engineered barriers system swells when saturated by groundwater. As a result of this swelling, buffer may penetrate into the peripheral rock zone surrounding the buffer through open fractures. It sustained for extremely long periods of time, the buffer extrusion could lead to reduction of buffer density, which may in turn degrade the assumed performance. In this report, the viscosity of bentonite was measured as one of the parameter of diffusion model. In addition, the simulation analysis was carried out to confirm the applicability of diffusion model. Moreover, an analytical evaluation on extrusion behavior of buffer into rock fractures was performed due to estimate the long-term stability of buffer as reduction of density.
Kanno, Takeshi*; Iwata, Yumiko*
JNC TJ8400 2003-083, 65 Pages, 2004/02
JNC-TJ8400-2003-083.pdf:0.81MB
Modelling study on the extrusion phenomenon of the bentonite in a geological repository for the high-level radioactive is performed to enhance the reliability of latest model studied on fiscal year 2003(H14), on the matter of density distribution of extruded bentonite gel. In this study, the model is reconsidered and revised based on the result of comparison between experimental and calculated results. The numerical analyses for BENTFLOW type experiments and model experiments on extrusion in a pipe are performed using the revised model. The analyses for the BENTFLOW about distribution of extrusion density reproduce the experimental results tolerably. The agreement between the calculated and experimental results of the model experiments are not good. Our model is originated in solid diffusion model of swelling clay proposed by Nakano et al. To enhance the reliability of our model, the latest model is reviewed by experts. At last, the numerical analyses for H12 type repository are performed by revised model to evaluate the long-term reduction of bentonite density for the extrusion phenomenon. The analytical results are compared with the results described in H12 report.
Fukunaga, Sakae*; Iwata, Yumiko*; Kanno, Takeshi*; Kudo, Akira*
JNC TJ8400 2003-070, 45 Pages, 2003/02
JNC-TJ8400-2003-070.pdf:0.13MB
This report summarizes two investigations concerned with microbial influence in geological disposal facilities. 1)Literature survey on simulation models for the microbial-influence evaluation, 2) Experiment for the interaction between bacteria and Pu at Eh=-135mV.
Fukunaga, Sakae*; Iwata, Yumiko*; Kanno, Takeshi*; Kudo, Akira*
JNC TJ8400 2003-069, 73 Pages, 2003/02
JNC-TJ8400-2003-069.pdf:0.39MB
This report summarizes two investigations concerned with microbial influence in geological disposal facilities. 1)Literature surevey on simulation models for the microbial-influence evaluation. 2)Interaction between Sulfate reducing bacteria(SRB) and Pu. For simulation models, we found some papers on gas production, geochemistry, microbial corrosion and microbial amount. To make the microbial-influence evaluation more reliable, it will be necessary to study subjects such as biodegradability of organic matter, microbial amount and certification of models. The sorption experiment for Pu onto SRB was conducted. It resulted in that effects of sterilization on the distribution coefficientat were not evident at Eh=-135mV.
Kanno, Takeshi*; Iwata, Yumiko*
JNC TJ8400 2003-026, 63 Pages, 2003/02
JNC-TJ8400-2003-026.pdf:0.56MB
Modelling study on the extrusion phenomenon in a geological repository for the high-level radioactive is performed to enhance the reliability of existing model described in H12 report. Main conclusions of this study are as follows: (1) The methods and pysical interpretation of bentonite gel viscosity measurements are clarified and input data of the viscosity for the solid diffusivity are obtained. (2) The input data of the swelling pressure and hydraulic conductivity of bentonite in the low- density region necessary for the solid diffusivity are determined. (3) The consolidation-type model proposed by Ahn et al. is surveyed and compared with that used in this study. The consolidation-type model is thought to be equivalent to the solid diffusion model used in this study. (4) The numerical analyses for BENTFLOW experiments and model experiments on extrusion in a pipe are performed. The analyses for the BENTFLOW reproduce the experimental results better than the past studies. The agreement between the calculated and experimental results of the model experiments is not good. Thus further study is required for the evaluation of density distribution in extruding bentonite gel.
Yamazaki, Kazutoshi*; Takao, Hajime*; Kikuchi, Takahiro*; Kuriki, Yoshiro*; Kobayashi, Masato*; Kawakubo, Masahiro*; Shirase, Mitsuyasu*; Iwata, Yumiko*; Tochigi, Yoshikatsu*; Nakayama, Gen*; et al.
no journal, ,
Among factors affecting the corrosion behavior of carbon steel overpack, in order to consider materials (size) and realistic environmental factors which are difficult to reproduce in the laboratory scale test, engineering scale tests in the underground environment were carried out. A mock-up test of the same scale was also carried out on the ground with the aim of controlling and evaluating factors that govern the corrosion phenomenon. As a result of the test for about 3 years, there was no big difference between the average corrosion amount and the maximum corrosion amount of the simulated overpack base metal and the welded part. On the other hand, unlike the laboratory scale test, localization of corrosion due to the adhesion between the buffer material and the simulated overpack was also confirmed during the initial transient period.