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*; *; Morooka, Koichi*
JNC TJ8400 2000-043, 170 Pages, 2000/03
JNC-TJ8400-2000-043.pdf:7.63MB
This study is an object to collect and arrange data about the mass transfer path during a natural barrier system by grasping actual rock feature, in order to be useful for a performance assessment of a natural barrier system at geological disposal of HLW. An existence of permeability high large-scale faults extends a large influence over a performance assessment of geological disposal. With "The Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan" which Nuclear Cycle Development Institute (JNC) issued, it is as" A repository would be located at least 100 meters away from major faults and major fracture zones which could adversely affect the stability and performance of the repository" as a Reference Case concept model of a natural barrier system, Then, they are as "in the Reference Case, the transport path consists of the host rock and the downstream fault". It will not be easy to know the distribution of faults in the subsurface deep division without data acquired from many boreholes and underground laboratory. With this study, specific data on the large-scale faults and fracture zones has been collected and arranged by investigating in underground galleries and on the literatures of a post-operated mine site. Based on this result, a consideration on the principal transfer pass at a natural barrier system has been conducted. The contents conducted in this report is the follows. (1)investigation of literature about data of fracture, shear zone, and geology, (2)field investigation of fracture and shear zone in the rock, (3)arrangement of these results, (4)modeling of the major water conductive feature, and (5)evaluation of an assumption which has been introduced in the Second Progress Report issued by JNC.
Sato, Haruo
JNC TN8400 99-061, 9 Pages, 1999/10
The porosities and dry densities for rock samples sampled from a fractured zone (fracture type C: composed of intact ganodiorite, altered ganodiorite and fracture fillings) at the Kamaishi mine were obtained by a water saturation (intrusion) method as input parameters for nuclide migration analysis in performance assessment of the geological disposal of high-level radioactive waste. Consequently, the average porosity, 8.6
0.43% was higher than those of fracture fillings, altered garnodiorite and intact ganodiorite composing fracture type B with a single fracture taken from the Kamaishi mine so far. While, the average dry density, 2.430.0089 Mg
m
, was lower than those of rocks composing the fracture type B. Based on this, it is predicted that radionuclides are the easiest to migrate in the fracture zone.
PNC TN8410 94-269, 77 Pages, 1994/07
This report describes FracMan discrete fracture flow transport modelling of the LPT-2, large-scale pumping and tracer test, at the SKB Aspo Hard Rock Laboratory. This work was carried out under the international cooperation program of the AsPo Task Force on Groundwater Flow and Transport of Solutes. The scale of simulation was approximately a one-kilometer cube. The discrete fracture model contains two major fracture types - fracture zones, which were located deterministically according to SKB's conceptual model of the Aspo site, and fractures outside the fracture zones which were generated stochastically. The geometric and hydraulic properties of each group were developed from the SKB modeling database, except for non-zone fracture length which we developed from our own mapping of surface outcrops. Two separate models were prepared for the March and September, 1993, task force meetings respectively. The March model represented the fracture zones as 10-m thick Planar regions containing populations of 30-m radius discrete fractures. The September model represented the fracture zones as single planes, which were discretized on a 20- to 30-m scale for a geostatistical assignment of properties. The September model also included conditioning of the properties to the borehole data. Both models generally reproduce the drawdown and transient pressure interference responses of the experiment. The tracer breakthroughs were simulated using only the September model. Calibration runs of the transport model varied the mean transport aperture, aperture variance, and aperture correlation length. The results of this modelling exercise show that a discrete fracture model can be applied at kilometer scales if the flow is dominated by a small portion of fracture population. The results also show that the SKB conceptual model is consistent with the field measurements.
Ishimaru, Tsuneari; Shimada, Koji; Sueoka, Shigeru; Yasue, Kenichi; Niwa, Masakazu; Umeda, Koji
no journal, ,
The Nuclear Regulation Authority (NRA) instructed to develop a further additional research plan regarding the crushed zones on the Monju site against the JAEA on September 25, 2013. The JAEA developed a research plan in response to this instruction, and, the stripping investigation with expansion of the area, the additional detailed geographical and geological surveys in the mountains/terrace boundary, and the marine seismic surveys in the coastal waters, were conducted. And, the JAEA was submitted to the NRA "Compilation Report" on March 28, 2014. From the investigation results so far, no clear evidence was observed to support that the on-site crushed zones are active faults. And, in the sea and land vicinity of the site, other than to the Shiraki-Nyu active fault, structure associated with the active fault is not recognized. From the plastic deformation of the biotite which is observed in the latest shear plane, the on-site crushed zones are considered to be a geological structure of the pre-Quaternary, which is formed in the deep underground environment of the several kilometers.
Shimada, Koji; Ishimaru, Tsuneari; Sueoka, Shigeru; Yasue, Kenichi; Niwa, Masakazu; Umeda, Koji
no journal, ,
Shear sense inversion of small crush zones is observed in the Kojaku granite. Two group of small crush zones are observed in basement granitic rock at the Monju site based on the strike and dip of these zones: NNE group and ENE group. Two types of fault core is also discriminated. Inversions of shear sense are observed in the both groups as well as types of crush zones. A sinistral sense of shear was followed by dextral one at the ENE group, and a dextral sense of shear was followed by sinistral one at the NNE group. We describe occurrences of the two groups, two types of crush zones and microstructures including sense of shear.
Shimada, Koji
no journal, ,
In this preliminary study, more objective discrimination between orientations of small crush zones was carried out by means of directional statistics. Fitted number of mixture components of von Mises distribution is eight. A probability distribution function curve of eight components mixture shows two peaks. Crush zones principally depict dextral sense of shear along the system beta, and sinistral one along the system alpha-3. Plastically deformed biotite grains are observed in both crush zones. Deformation temperature of them seems to be higher. Statistically comparable development, nearly orthorhombic symmetry, and cross cutting relationship between the two systems suggest the development of crush zones in conjugate manner. This movement picture is inconsistent with continuing E-W shortening during late Quaternary. These lines of evidence suggest that crush zones observed at the site of Monju are old geologic structure.
Ishimaru, Tsuneari; Shimada, Koji; Sueoka, Shigeru; Yasue, Kenichi; Niwa, Masakazu; Umeda, Koji
no journal, ,
In JAEA, geological investigation of fracture zones has been carried out at the Monju site based on the instruction received from the Nuclear Regulation Authority. Results of the investigation, it has shown that no clear evidence was observed to indicate that on-site fracture zones are active faults. In the activity evaluation of the on-site fracture zones, we examined cross-cutting relationships of fractures in detail, and we estimated that these fracture zones are older small-scale geological structure which was formed under the high-temperature environment of the deep part before exposure of the granitic body from the microscopic observation of the plastic deformation of biotite grains in the fracture zones and the deformation twins in the calcite veins along the fracture zones. This investigation of fracture zones is considered one of good examples shown that it is possible to evaluated activity of fracture zones in granite.
Shimada, Koji; Ishimaru, Tsuneari; Sueoka, Shigeru; Terusawa, Shuji; Yasue, Kenichi; Niwa, Masakazu; Umeda, Koji
no journal, ,
Diverse situation of outcropping crush zones around important building constructions need upgrading of activity evaluation method without the use of overlying sediments. The method using the cross-cutting relations among geologic features in basement rocks is promising. However, minor crush zones without cross-cutting relation are frequently observed. An activity evaluation of such minor crush zone was carried out in one outcrop. The confirmation of an extension of the crush zone, age estimation of young overlying sediments, comparison of sense of shear of clay vein, comparison of outcrop morphology with another crush zone, and clay grain-size measurement of the near active fault and the crush zone are carried out. The results suggest that the crush zone is not an active fault or a weak zone which slips accompanied with the active zone.
Shimada, Koji; Sueoka, Shigeru; Ishimaru, Tsuneari
no journal, ,
The application of overlying sediments is one of the methods defining relative age based on the principle of cross-cutting relations. This principle is one of the geological principles indicating relative age of deformation features such as faulting or tectono-metamorphic textures. The application of overlying sediments and relative age determination of deformation features are also based on the principle of cross-cut relations. We present a method utilize relative deformation age by means of the cross-cut relations, temperature gauges shown by structures, and thermal history of geological body alternative to the application of overlying sediments. Research area is located near the FBR Monju. Data suggest that the activity of crush zones precede basaltic dyke formation under higher temperature environment. This research method is potential alternative, though case study is needed towards overcoming the unsuitable outcropping situation to grasp basic geological data.