Excavation cycle times recorded during sinking of a deep shaft in crystalline rock; A Case example at ventilation shaft of Mizunami URL, Japan

Sanada, Hiroyuki; Sato, Toshinori; Horiuchi, Yasuharu*; Mikake, Shinichiro; Okihara, Mitsunobu*; Yahagi, Ryoji*; Kobayashi, Shinji*

Tunnelling and Underground Space Technology, 50, p.68 - 78, 2015/08

https://doi.org/10.1016/j.tust.2015.06.012

The Japan Atomic Energy Agency (JAEA) is implementing the Mizunami Underground Research Laboratory (MIU) Project to establish the scientific and technological basis for the geological disposal of High-level Radioactive Waste (HLW) in crystalline rocks. Excavation cycle times were recorded during the Ventilation Shaft sinking and compared with the planned excavation cycle times for evaluation of the baseline design plan. This included review of the cycle times in the design process and comparison with the actual construction results. The recorded results indicate that actual cycle times were twice as long as the design plan. This paper describes discussions on differences in cycle times between the design and actual times.

Analysis of excavation cycle time during sinking of the ventilation shaft at the Mizunami Underground Research Laboratory

Sanada, Hiroyuki; Sato, Toshinori; Horiuchi, Yasuharu*; Mikake, Shinichiro; Okihara, Mitsunobu*; Yahagi, Ryoji*; Kobayashi, Shinji*

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 7 Pages, 2014/10

The Japan Atomic Energy Agency (JAEA) is implementing the Mizunami Underground Research Laboratory (MIU) Project to establish the scientific and technological basis for the geological disposal of High-level Radioactive Waste (HLW) in crystalline rocks. Excavation cycle times were recorded during the Ventilation Shaft sinking and compared with the planned excavation cycle times for evaluation of the baseline design plan. This included review of the cycle times in the design process and comparison with the actual construction results. The recorded results indicate that actual cycle times were twice as long as the design plan. This paper describes discussions on differences in cycle times between the design and result.

Report on decontamination pilot projects to establish guidelines for environmental remediation of residential areas contaminated with radioactive materials discharged from the Fukushima Daiichi Nuclear Power Station Accident

Kihara, Shinji; Amazawa, Hiroya; Sakai, Akihiro; Nakata, Hisakazu; Kugo, Teruhiko; Matsuda, Norihiro; Oizumi, Akito; Sasamoto, Hiroshi; Mitsui, Seiichiro; Miyahara, Kaname

JAEA-Research 2013-033, 320 Pages, 2014/07

JAEA-Research-2013-033.pdf:119.17MB

JAEA performed decontamination experiments at two test sites that combined a range of buildings and different types of land use, located in Date and Minami Soma municipalities as field pilot projects in order to accumulate knowledge and data for full-scale decontamination activities performed by local governments. In the pilot projects, we established its plan using practical decontamination methods that can be easily implemented, according to decontamination targets (e.g., forests, agricultural land, residential house and roads) at each site. As a result of the decontamination, the average air dose rates were reduced to approximately one half of the values before decontamination.

Selection of main nuclides from the viewpoint of safety assessment for near surface disposal of low-level radioactive waste generated from research, industrial and medical facilities, 3; Preliminary selection of important radionuclides contained in low-level radioactive waste generated from major research facilities

Sakai, Akihiro; Amazawa, Hiroya; Nakata, Hisakazu; Takahashi, Kuniaki; Kihara, Shinji

JAEA-Technology 2010-021, 152 Pages, 2010/07

JAEA-Technology-2010-021.pdf:7.87MB

Total radioactivity and radioactive concentration limit of nuclides in low level radioactive waste that are expected to cause relatively large dose in near surface disposal are needed to be described in the licensing application form, as so-called "main nuclides", for disposal business of LLW generated from research, industrial and medical facilities. In this report, as an example, the main nuclides were preliminarily selected out of the nuclides contained in LLW generated from main research reactors and PIE facilities in Nuclear Science Research Institute of JAEA, by use of nuclide composition ratios in the wastes and their radioactivity concentration limit of near surface disposal derived by Nuclear Safety Commission in Japan. As results of preliminary selection of main nuclides without fixed radioactive inventory in the wastes, 24, 30 and 33 nuclides were selected as main nuclides for LLW from the reactors, PIE facilities, and both facilities, respectively.

Selection of important nuclides from the viewpoint of safety assessment for disposal of radioactive waste arising from research institutes, 2; Analytical scheme for nuclide composition in radwastes arising from research and testing reactor and post-irradiation examination facilities

Asai, Shiho; Sakai, Akihiro; Yoshimori, Michiro; Kihara, Shinji

JAERI-Tech 2003-071, 46 Pages, 2003/08

JAERI-Tech-2003-071.pdf:4.31MB

As part of survey concerning radioactive inventory of radwastes arising from research institutes, an analytical scheme has been studied for verifying their nuclide composition based on calculation analysis and record, in consideration of the its characteristics. In this study, radwastes are used as samples, which arise from research and testing reactors and post-irradiation examination facilities (PIE facilities). Though separation procedures are simplified and rationalized, quantifiable values could be obtained with relative errors under 10% for almost all the samples containing nuclides like Ni and U which concentrations are low, and recoveries were high on the whole. These show that the analytical scheme is useful for chemical separation of radwastes arising from research and testing reactors and PIE facilities.

Dechlorinating reaction of organic chlorides

Yahata, Taneaki*; Kihara, Shinji;

JAERI-Research 96-035, 24 Pages, 1996/06

JAERI-Research-96-035.pdf:0.97MB

no abstracts in English

Incineration of spent ion exchange resins in combination with fluidized bed and catalyst

Yahata, Taneaki; Kihara, Shinji; Hirata, Masaru; Abe, Masayoshi

1992 Incineration Conf. Proc., p.311 - 315, 1992/00

no abstracts in English

Irradiation behavior of MA-containing MOX fuel, 7; Metallographic examination of Np/Am-MOX fuel irradiated for 24 hours in JOYO

Maeda, Koji; Sasaki, Shinji; Kato, Masato; Kihara, Yoshiyuki; Osato, Yukihiro*; Onuma, Yasuhiro*; Nukaga, Sadayoshi*

no journal, , 

no abstracts in English

Results of the program to develope guidelines for decontamination, 3; Demonstration project of decontamination at Heart Land Haramachi in Minami-soma city

Amazawa, Hiroya; Sakai, Akihiro; Nakata, Hisakazu; Miyahara, Kaname; Kihara, Shinji

no journal, , 

JAEA performed decontamination experiments at a test site (Heart Land Haramachi) that combined a range of buildings and different types of land use, located in Minami Soma city as a field decontamination project in order to accumulate knowledge and data for full-scale decontamination. As a result of the decontamination that was performed using methods that can be easily implemented, taking into consideration the topography and land use of the target area, the average air dose rates were reduced to approximately one half of the values before decontamination. In addition, it was confirmed that, to reduce the exposure doses of people living in houses adjacent to a contaminated forest, a sufficient effect can be obtained by decontaminating the forest to a depth of 10 m from the forest boundary. For contaminated asphalt-paved roads, decontamination by shot blasting was effective.