Information collection regarding geoscientific monitoring techniques during closure of underground facility in crystalline rock

Hosoya, Shinichi*; Yamashita, Tadashi*; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onoe, Hironori; Ishibashi, Masayuki

JAEA-Technology 2015-027, 128 Pages, 2016/01

JAEA-Technology-2015-027.pdf:33.66MB

The study for development of drift backfilling technologies is one of the critical issues in the Mizunami Underground Research Laboratory (MIU) project, and its purposes are to develop closure methodology and technology, and long-term monitoring technology, and to evaluate resilience of geological environment. To achieve the purposes, previous information from the case example of underground facility constructed in crystalline rock in Europe has been collected. In particular, the boundary conditions for the closure, geological characteristics, technical specifications, and method of monitoring have been focused. The information on the international project regarding drift closure test and development of monitoring technologies has also been collected. In addition, interviews were conducted to specialists who have experiences involving planning, construction management, monitoring, and safety assessment for the closure. Based on the collected information, concept and point of attention, which are regarding drift closure testing, and planning, execution management and monitoring on the closure of MIU, have been specified.

Uranium recovery in LWR reprocessing and plutonium/residual uranium conditioning in FBR reprocessing for the transition from LWR to FBR

Fukasawa, Tetsuo*; Yamashita, Junichi*; Hoshino, Kuniyoshi*; Sasahira, Akira*; Inoue, Tadashi*; Minato, Kazuo; Sato, Seichi*

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 7 Pages, 2008/05

In order to flexibly manage the transition period from LWR to FBR, the authors investigated the transition scenario and proposed the Flexible Fuel Cycle Initiative (FFCI). In FFCI, LWR spent fuel reprocessing only carries out the removal of about 90% uranium that will be purified and utilized in LWR after re-enrichment. The residual material (40% U, 15% Pu and 45% other nuclides) is transferred to temporary storage and/or FBR spent fuel reprocessing to recover Pu/U followed by FBR fresh fuel fabrication depending on the FBR introduction status. The FFCI has some merits compared with ordinary system that consists of full reprocessing facilities for both LWR and FBR spent fuels, that is smaller LWR reprocessing facility, spent LWR fuel reduction, storage and supply of high proliferation resistant and high Pu density material that can flexibly respond to FBR introduction rate changes. The Pu balance was calculated under several cases, which revealed that the FFCI could supply enough Pu to FBR in any cases.

Geological Structure Modeling Around Mill Tailing Yard

Takano, Hitoshi*; Sugimoto, Yoshihiro*; Yamashita, Tadashi*; Yamada, Naoyuki*

JNC TJ6420 2003-011, 127 Pages, 2003/02

JNC-TJ6420-2003-011.pdf:4.56MB

Drilling and high resolution electrical survey was carried out to make a geological structure model around mill tailing yard. Following by drill investigation, Distribution of the granite which became fragility was confirmed by the development of fractures with hydrothermal vein. However, fresh bedrock is distributed deeper than 40m. Permeability of weathering granite is about in 1.1510m/sec. The value agrees previous findings. In fresh granite, permeability is 4.3310m/sec, and it value is larger than existing data. It is for developing of fractures in fresh granite. At high resolution electrical survey, analysis is done by 3 dimensions. By analyzing it with 3 dimensions, good resistivity distribution was provided. From resistivity distribution, tailing, weathered granite or sedimentary rock and fresh granite are classified. Resistivity distribution was taken out from lines or seismic exploration refraction method, and compared between two methods. As a result, low resistivity region is fitted low velocity zone and high resistivity region is fitted high velocity zone. Topography and 4 geological models are created. These models are output as versatile text data to show relation of a coordinate and the point of contact.