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Saito, Yuya; Tanai, Kenji; Kikuchi, Hirohito*; Hirai, Takashi*; Nishimura, Mayuka*
JAEA-Research 2008-010, 35 Pages, 2008/03
JAEA-Research-2008-010.pdf:15.56MB
Site with the potential to adversely affect the performance of the disposal system should be avoided by site selection in Japan. On the other hand, according to Atomic Energy Commission, the possibility to occur the natural and artificial events suddenly should be examined. So it is important to examine about the critical state of the engineering barrier system (EBS) when if the fault move across the EBS. And this study helps to be understood by the nation. In this paper, we examined the influence of the velocity of fault movement by the model test, and tried to improve the precision of the simulation analysis. Test results showed that the total pressure of the buffer inside was about 20% decreased when the velocity was a one-tenth. And it is important to set the permeability of the near-field rock appropriately when simulating the behavior of the buffer material affected by fault movement.
Fujita, Tomoo; Taniguchi, Naoki; Matsui, Hiroya; Tanai, Kenji; Nishimura, Mayuka; Kobayashi, Yasushi; Hiramoto, Masayuki; Maekawa, Keisuke; Sawada, Atsushi; Makino, Hitoshi; et al.
JAEA-Research 2007-045, 140 Pages, 2007/03
JAEA-Research-2007-045-1.pdf:38.33MBJAEA-Research-2007-045-2.pdf:44.62MB
This report summarizes the progress of research and development on geological disposal during the surface-based investigation phase (2001-2005) in the Horonobe Underground Research Laboratory project (HOR), of which aims are to apply the design methods of geological disposal and mass transport analysis to actual geological environments and derive future subjects based on the results. The design methods of geological disposal were reviewed based on the recent knowledge and the advertences were identified. Then the parameters for virtual design of engineered barrier system, backfill deposition hole and tunnel were set up based on actual geological conditions obtained from the surface-based investigations in HOR as an example of actual geological environment. The conceptual structure from site investigation and evaluation to mass transport analysis was represented as a work flow at first. Then following this work flow a series of procedures for mass transport analysis were carried out based on actual geological conditions obtained from the surface-based investigations in HOR to illustrate the functioning of the work flow and the applicability of this methodology. Consequently, knowledge that will help follow-up or future execution and planning activities was obtained.
Nishimura, Mayuka; Tanai, Kenji; Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Shimogochi, Takafumi*
JAEA-Research 2007-004, 87 Pages, 2007/03
JAEA-Research-2007-004.pdf:14.61MB
The 3-D mechanical coupled analysis technique for the near field is developed, upgrading a 2-D non-coupled technique for the buffer material. The analysis object is extended to the disposal gallery and the near field rock, in addition to the EBS. And following problems are approached; (1) modeling the near field rock with the valuable- compliance-type constitutive equation, (2) modeling a degraded behavior of the concrete support, (3) changing the expanding deform method of the overpack corrosion, (4) examining the effect of drainage conditions on water pressure behavior of the near field rock, (5) setting parameters of the backfill material modeled with Sekiguchi-Ohta model. The prototype model is developed adopting the result for the above approaches, excluding a degradation model of concrete support. The result of long term analysis with the prototype model shows a reasonable behavior of the near field that reflects the models of the near field rock and the backfill material.
Nishimura, Mayuka; Tanai, Kenji; Takaji, Kazuhiko*; Hirai, Takashi*; Shiratake, Toshikazu*
JAEA-Research 2006-036, 82 Pages, 2006/06
JAEA-Research-2006-036.pdf:4.09MB
In order to evaluate the long term mechanical behavior of the Enginnered Barrier System (EBS), it is essential to set suitable parameters of constitutive models of the buffer material. In this report, the parameters of the Sekiguchi-Ohta model and the Adachi-Oka model are examined. The results are as follows; it is impossible to set the sole parameter which can evaluate both the deformation and the stress of the buffer material. But when selecting a suitable parameter for the object of evaluation, the mechanical behavior of buffer material can be approximately described. On the other hand, the range of the secondary consolidation coefficient of the bentonite ore is estimated to corroborate to the viscous parameter of the buffer material, using a natural analogue study. Finally, the mechanical behavior of the buffer material is analyzed using these parameters, and the maximum amount of settling of the overpack is estimated.
Tanai, Kenji; Jintoku, Takashi*; Kikuchi, Hirohito*; Nishimura, Mayuka; Matsumoto, Kazuhiro*; Aoyanagi, Shigeo; Yui, Mikazu
JAEA-Research 2006-035, 32 Pages, 2006/06
JAEA-Research-2006-035.pdf:3.46MB
In order to contribute to the safety standards and guidelines which a regulator decides, state-of the art assessment method is investigated and summarized in the table about performance guarantee contents of buffer material related to the mechanical support and protection of the overpack and rock matrix, and the retardation of radionuclide. In addition, examples of the assessment tool are described. In this report, summary of (1) basic properties of bentonite, including swelling properties, mechanical properties and hydraulic properties, (2) long-term behavior of bentonite, including creep deformation, penetration into host rock, erosion and alteration, (3) gas permeability, (4) colloid filtration and (5) mechanical stability of the near-field is described. Check points, assessment methods (based on the data obtained from the experimental results, the estimation value obtained from empirical equations and database, and the modeling calculations) and latest results of these R&D programs were also summarized.
Aoyanagi, Shigeo; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Fujita, Tomoo; Taniguchi, Naoki; Shibata, Masahiro; Konishi, Kazuhiro; Nishimura, Mayuka; Kikuchi, Hirohito*; et al.
JAEA-Review 2006-014, 61 Pages, 2006/03
JAEA-Review-2006-014.pdf:5.03MB
no abstracts in English
Aoyanagi, Shigeo; Oda, Yoshihiro; Sasamoto, Hiroshi; Shibata, Masahiro; Tanai, Kenji; Taniguchi, Naoki; Nishimura, Mayuka; Fujisaki, Kiyoshi; Kikuchi, Hirohito*; Matsumoto, Kazuhiro*
Hoshasei Haikibutsu Anzen Kenkyu Nenji Keikaku (Heisei-13-Nendo
Heisei-17-Nendo) Kenkyu Seika Hokokushu, p.179 - 203, 2006/03
no abstracts in English
Nishimura, Mayuka; Hirai, Takashi*; Tanai, Kenji; Yui, Mikazu
Materials Research Society Symposium Proceedings, Vol.932, p.227 - 234, 2006/00
The objective of this study is to clarify mechanical effect of engineered barrier system to a fault movement presupposed to occur on geological disposal of high-level radioactive waste. The plan of this study is; (1) to understand mechanical behavior of buffer when shearing takes place in laboratory simulated tests, and (2) to make progress in numerical analysis techniques in order to estimate the effect of fault movement on engineered barrier system on disposal site. Accordingly, first, laboratory simulated tests were carried out with a 1:20 model of engineered barrier system. The experimental results represented that the increased total pressure was mainly due to the increase of pore water pressure. Secondly, the model test was simulated with the help of the finite element method. The calculation results showed that the degree of water draining from buffer into outside affected on the behavior of the pressure increase. It also showed the calculation expressed the experimental results roughly with a proper parameter of permeability of buffer surrounding material.
Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Tanai, Kenji; Nishimura, Mayuka
no journal, ,
no abstracts in English
Shigeno, Yoshimasa*; Takaji, Kazuhiko*; Nishimura, Mayuka*; Tanai, Kenji
no journal, ,
no abstracts in English
Nishimura, Mayuka*; Shigeno, Yoshimasa*; Takaji, Kazuhiko*; Tanai, Kenji
no journal, ,
no abstracts in English
Saito, Yuya; Tanai, Kenji; Kikuchi, Hirohito*; Hirai, Takashi*; Nishimura, Mayuka*
no journal, ,
no abstracts in English