Kawaguchi, Masanao; Kishi, Hirokazu*; Fujita, Tomo; Kishida, Kiyoshi*
Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.337 - 342, 2013/01
For the selection of grout material for the construction of underground facilities for the geological disposal of High Level Waste, the criteria that is set by reference to IMA-project(which was a project of the grout material relating to the R20 program was conducted by POSIVA of Finland), has been used up to FY 2010. However, if the criteria of penetrability are fulfilled, the penetrability of the material for the candidate rock fracture is not ensured. Moreover, from the results of laboratory grout penetration test which has been carried out at FY 2010, it was appeared that the penetrability has been scarified in order to satisfy the strength and breeding characteristics. In this report, strength and bleeding properties are classified as reference properties, not as principal properties. Instead of that, new criteria of penetrability defined based on geological features at the site are proposed. Also the determination procedure of designed hydraulic fracture aperture which is one of above newly proposed criteria will be proposed.
Kawaguchi, Masanao; Nakanishi, Tatsuro; Kishi, Hirokazu; Nobuto, Jun*; Yamada, Tsutomu*; Fujita, Tomo; Hatanaka, Koichiro
JAEA-Data/Code 2012-007, 250 Pages, 2012/11
Cementitious materials are commonly used for rock support, lining, and grouting, their pH plume are considered to have an adverse effect on long-term safety of a geological disposal system. In addition, during the emplacement of waste package with buffer material, it is required to limit amount of groundwater inflow to a certain level by grouting. Therefore, it is necessary to develop new grout materials with penetrability for smaller fractures. We have developed new grout materials, which have better penetrability and are environmentally more friendly than exinting cementitious grout materials since FY 2007. This sequel report shows the most appropriate composition and the penetration characteristic of new grout materials to be suitable for the experiment based on the result of indoor test carried out after FY 2008.
Fujita, Tomo; Kawaguchi, Masanao; Walker, C.; Sasamoto, Hiroshi; Yui, Mikazu; Onishi, Yuzo*
Proceedings of 7th Asian Rock Mechanics Symposium (ARMS-7) (USB Flash Drive), p.675 - 681, 2012/10
The Japan Atomic Energy Agency started new grout project for geological disposal of high-level radioactive waste in 2007. This study presented the overall JAEA grout project program and an example of how to apply key engineering technologies to the construction and operation of an underground facility for the geological disposal of HLW.
Kishi, Hirokazu; Kawaguchi, Masanao; Naito, Morimasa; Hatanaka, Koichiro; Nobuto, Jun*; Sugiyama, Hirokazu*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 19(1), p.3 - 8, 2012/06
To reduce amount of groundwater inflow into a geological repository, the grouting is expected to play a very important role because the geological environment in Japan is often characterized by many fractures and abundant groundwater. Basically, cementitious materials are used for grouting, however the resulting highly alkaline plume released from the materials could influence the long-term performance of barrier system as a consequence of alteration of both the buffer material and the host rock. To minimize such effects, JAEA has carried out research and development on three types of grout material with low-pH performance that decreases influence in the alteration. This paper focuses on the Colloidal silica grout, and presents its unique characteristics obtained from laboratory tests on pH, viscosity, leaching and so on. The results indicate that the grout has good performances in pH and viscosity. It is concluded that the grout can be greatly used for the repository.
Kawaguchi, Masanao; Kishi, Hirokazu; Nobuto, Jun*; Sugiyama, Hirokazu*
Doboku Gakkai Heisei-23-Nendo Zenkoku Taikai Dai-66-Kai Nenji Gakujutsu Koenkai Koen Gaiyoshu (DVD-ROM), p.67 - 68, 2011/09
no abstracts in English
Nakanishi, Tatsuro; Kawaguchi, Masanao; Tsuda, Hidenori; Uyama, Masao*; Tanaka, Tatsuya*
Doboku Gakkai Heisei-23-Nendo Zenkoku Taikai Dai-66-Kai Nenji Gakujutsu Koenkai Koen Gaiyoshu (DVD-ROM), p.71 - 72, 2011/09
no abstracts in English
Nagao, Keisuke*; Okazaki, Ryuji*; Nakamura, Tomoki*; Miura, Yayoi*; Osawa, Takahito; Bajo, Kenichi*; Matsuda, Shintaro*; Ebihara, Mitsuru*; Ireland, T.*; Kitajima, Fumio*; et al.
Science, 333(6046), p.1128 - 1131, 2011/08
A steroid surface materials record regolith processes and a history of cosmic-ray irradiation. Noble gas isotopes in three rocky grains from Itokawa have been determined. High concentrations of solar He, Ne, and Ar, as high as those in lunar soils, are released at variable temperatures from each sample. The isotopic compositions are essentially identical to those of solar wind but distinguishable in He relative abundance. These noble gas characteristics can be explained by repeated implantation and preferential loss of solar He by removal of weathered He-rich rim on the grain surface through friction among regolith grains on Itokawa. Residence time of regolith materials on Itokawa is alculated to be shorter than 10 Myr, suggesting that regolith materials of small asteroids would escape easily to space.