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Murakami, Hiroaki; Ashizawa, Masaomi*; Tanaka, Kazuhiro*
Oyo Chishitsu, 59(1), p.2 - 12, 2018/04
This study describes the features of fractures and their fillings along with the long-term behavior of their hydrogeological structures in an underground environment based on the results of a geological investigation conducted at an underground facility in northern Kyushu. Fractures were classified into five groups on the basis of fracture orientation: A, B, C, D, and low-angle groups. The genesis of all fractures is the cooling process of granodiorite pluton. Almost all of the water-conducting fractures are included in the B group. Because a number of fracture fillings in the B group are filled by prehnite and crushed fragments of epidote and quartz, the fractures in this group alternated sealing and re-opening. The fracture characteristics in the B group are follow as: accompanying many alteration halos, long trace length, and cutting off other fractures. These results indicate that fractures in the B group have possibly functioned as pathways for groundwater flow in the long term.
Murakami, Hiroaki; Tanaka, Kazuhiro*
Chikasui Gakkai-Shi, 57(4), p.415 - 433, 2015/11
This study examined the geochemical properties and the distribution of mineral spring water, river water and bubbling gas in the Tsuwano Town, Shimane Prefecture, Western Japan. In Tsuwano, high Na-Cl concentration groundwater is discharged with bubbling gas mainly composed of CO
. The geochemical properties of mineral spring water, gas, hydrogen-oxygen isotopes and rare gas isotopes suggest that mineral spring water at Tsuwano possibly contains deep-seated fluid. In addition, the largest flux of the deep-seated fluid is found along active fault, suggesting that active fault acts as a path way for fluid upwelling. Furthermore, In Tsuwano, deep-seated fluid discharges along the Lake Ohara-West Yauneyama fault system and surface fracture.
Thiel, C.*; Tsukamoto, Sumiko*; Tokuyasu, Kayoko; Buylaert, J.-P.*; Murray, A. S.*; Tanaka, Kazuhiro*; Shirai, Masaaki*
Quaternary Geochronology, 29, p.16 - 29, 2015/08
Times Cited Count：11 Percentile：33.8(Geography, Physical)The applicability of both quartz and feldspar luminescence dating was tested on twenty-five samples from a marine succession now forming a cliff at Oga Peninsula, Honshu Island, Japan. The quartz shows thermal instability and linear modulated optically stimulated luminescence (LM-OSL) analysis revealed the dominance of a slow component. When compared with independent age control provided by two marker tephra, the quartz OSL ages grossly underestimated the depositional age. In contrast, potassium (K)-rich feldspar is a suitable dosimeter when measured using post-IR infrared stimulated luminescence (IRSL) at 225
C, but it was found that the fading corrected ages calculated using dose rates based on sieved grain-size still underestimate. SEM analyses on the feldspar extracts revealed that the grains are amorphous with small crystalline inclusions; using standard internal dose rate parameters, this would result in a too large dose rate. Three different dose rate scenarios were considered for calculation: (1) sieved grain size (90-180
m) and 12.5
0.5% K. (2) smaller grain size (4020m) and measured K concentration (60.5%), and (3) smaller grain size consistent with the observed crystal dimensions (4020m) and 12.50.5% K. The final dose rate scenario produces fading corrected ages that agree well with independent age control.
Tokuyasu, Kayoko; Tanaka, Kazuhiro*
Dai Yonki Kenkyu, 54(1), p.1 - 9, 2015/02
Optically stimulated luminescence (OSL) signal resetting of quartz grains from modern fluvial sediments (flood and river-bed sediments; four samples in total) were investigated to discuss the applicability of OSL dating for fluvial terrace sediments in Japan. Single aliquot regenerative dose (SAR) protocol was employed to estimate the residual doses of the samples. Residual doses from all samples range from 1.20.3 to 5.93.5 Gy, and the doses can be converted to the OSL age of 6-0.6 ka. We concluded that the OSL dating has the potential to remark the marine isotope stage (MIS) of fluvial terraces at around 100 ka.
Seki, Akiyuki; Takemiya, Hiroshi; Takahashi, Fumiaki; Saito, Kimiaki; Tanaka, Kei*; Takahashi, Yutaka*; Takemura, Kazuhiro*; Tsuzawa, Masaharu*
Progress in Nuclear Science and Technology (Internet), 4, p.47 - 50, 2014/04
The radionuclide distribution database and map system, which provide basic information for evaluations and countermeasures of the Fukushima nuclear accident, are explained. Due to massive earthquake and tsunami, Fukushima Dai-ichi Nuclear Power Plant has been damaged and had spread out radioactive materials around the Fukushima site. It is necessary to collect, analyze, and provide the information of radioactivity correctly and immediately. We developed two providing systems to identify the current distribution of released radionuclides and support decontamination activities.
mutantKiyosawa, Kazuhiro*; Tanaka, Masashi*; Matsunaga, Tsukasa*; Nikaido, Osamu*; Yamamoto, Kazuo
Mutation Research; DNA Repair, 487(3-4), p.149 - 156, 2001/12
no abstracts in English
Inoue, Daiei*; Honsho, Shizumitsu*; Tanaka, Kazuhiro*; Ueda, Keiichi*
JNC TJ1420 98-024, 73 Pages, 1990/06
None
Seki, Akiyuki; Takemiya, Hiroshi; Takahashi, Fumiaki; Saito, Kimiaki; Tanaka, Kei*; Takahashi, Yutaka*; Takemura, Kazuhiro*; Tsuzawa, Masaharu*
no journal, ,
Radioactive database and contamination map for the accident of Fukushima Dai-ichi Nuclear Power Plant are described. It is necessary to obtain precise data on the contamination conditions. Both systems have been developed to provide information to identify the current distribution of released materials and to support decontamination planning. The former is designed to provide quantitative data for detailed analysis, while another to provide intuitive images for the qualitative estimation. They contain air dose rates at around 2,200 locations within approximately 100 km from the plant, and radionuclide concentration data at each location. The vehicle-borne survey results are also included for the purpose of ascertaining the distribution of radioactive substances around roads in detail. All the data have been measured during the first investigation conducted in June, and the second in December 2011. The systems will become open to the public at the site of JAEA soon.
Seki, Akiyuki; Takemiya, Hiroshi; Saito, Osamu; Saito, Kimiaki; Tanaka, Kei*; Takahashi, Yutaka*; Takemura, Kazuhiro*; Tsuzawa, Masaharu*
no journal, ,
The system for saving and providing the data which are related to the radionuclides in Fukushima prefecture and the neighboring prefectures has been developed. The data mainly include the dose-rate and the analysis result of the soil and water samples. The Center for Computational Science and e-Systems developed the system under the study on distribution of radioactive substances around Fukushima Dai-ichi Nuclear Power Plant founded by MEXT. Proceeding with the installation of the data which are collected by MEXT and Fukushima prefecture, the system are being enhanced more.
Seki, Akiyuki; Takemiya, Hiroshi; Takahashi, Fumiaki; Saito, Kimiaki; Tanaka, Kei*; Takahashi, Yutaka*; Takemura, Kazuhiro*; Tsuzawa, Masaharu*
no journal, ,
The construction of the database and map systems, which provide basic information for evaluations and countermeasures of the Fukushima nuclear accident, are explained. Fukushima Daiichi Nuclear Power Plant had been damaged and spread out radioactive materials around there on March 2011. There are still a lot of requests to know the distribution of radioactive material from government, local government, residents, and/or researchers. In order to meet those requests, we developed two systems to provide those data to the public. One of the systems is a database system which is designed to provide quantitative data for detailed analysis. Another is a map system which provides intuitive images for the qualitative estimation.
Murakami, Hiroaki; Sasao, Eiji; Tanaka, Kazuhiro*
no journal, ,
no abstracts in English
