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Journal Articles

Development of a design support system for geological disposal of radioactive waste using a CIM concept

Sugita, Yutaka; Kageyama, Takeshi*; Makino, Hitoshi; Shimbo, Hiroshi*; Hane, Koji*; Kobayashi, Yuichi*; Fujisawa, Yasuo*; Makanae, Koji*; Yabuki, Nobuyoshi*

Proceedings of 17th International Conference on Computing in Civil and Building Engineering (ICCCBE 2018) (Internet), 8 Pages, 2018/06

This paper presents status of development of the iSRE (integrated system for repository engineering) as a design supporting system that enables rational designing of a geological disposal repository. The complimentary technique of construction information modeling/management (CIM) has been employed for the development of iSRE. CIM uses a shared three dimensional (3D) model of associated data through common data models. In this paper, as a design support system that conforms to the characteristics of information management about engineering technology represented by repetition of design during the disposal project period, we examined and designed the function of the "iSRE", constructed a prototype, and confirmed the function through a trial simulating actual work in the disposal project. As a result, with respect to the functions of DB and IF of the iSRE, we got a prospect that these functions can be the foundation of information management on engineering technology, and development of the prototype of the iSRE and its test run extracted issues for practical use of such system.

Journal Articles

Domain structure and electronic state in P3HT:PCBM blend thin films by soft X-ray resonant scattering

Kubota, Masato; Sakurai, Takeaki*; Miyadera, Tetsuhiko*; Nakao, Hironori*; Sugita, Takeshi*; Yoshida, Yuji*

Journal of Applied Physics, 120(16), p.165501_1 - 165501_5, 2016/10

 Percentile:100(Physics, Applied)

We performed soft X-ray resonant scattering experiments on P3HT:PCBM blend thin films to reveal the domain structure and electronic state, where P3HT and PCBM mean regioregular poly (3-hexylthiophene) and [6,6]-phenyl-C61-buteric acid methyl ester, respectively. We measured two films, where chloroform (CF sample) and 1,2-dichlorobenzene (DCB sample) are used as solvents in the fabrication process. There is negligible X-ray incident angle dependence of the X-ray absorption spectra at the S $$K$$-absorption edge in the CF sample, whereas the DCB sample exhibits clear incident angle dependence. We obtained the wave-number resolved spectra at $mbox{boldmath $Q$}$ = (1, 0, 0) for P3HT molecules in both samples. The packing growth of P3HT molecules is revealed to be much more developed in the DCB sample than the CF sample. In addition, the electronic structure at local sulfur element sites clearly changes for both of the samples.

Journal Articles

The Aerial radiation monitoring in Japan after the Fukushima Daiichi Nuclear Power Plant accident

Sanada, Yukihisa; Sugita, Takeshi; Nishizawa, Yukiyasu; Kondo, Atsuya*; Torii, Tatsuo

Progress in Nuclear Science and Technology (Internet), 4, p.76 - 80, 2014/04

The ambient dose-rate and the deposition concentration of radioactive cesium was measured by using helicopters in the whole area of Japan to investigate the influence of the radioactivity that released in the atmosphere due to the disaster of the Fukushima Daiichi NPP (Nuclear Power Plant), Tokyo Electric Power Company (TEPCO), occurred by the East Japan earthquake and tsunami on March 11, 2011. As a result, the deposition of radioactive cesium on the ground discharged from the Fukushima Daiichi NPP was obtained, and it was clarified that the scattered range of the cesium had been almost limited from the southern part of Tohoku to Kanto areas. The variation distribution of the dose-rate of Japan was also revealed in this measurement.

JAEA Reports

Radiation monitoring using the unmanned helicopter after the accident of the nuclear power plant

Sanada, Yukihisa; Nishizawa, Yukiyasu; Yamada, Tsutomu; Ikeda, Kazutaka*; Matsui, Masashi*; Tsuchida, Kiyofumi; Sato, Yoshiharu; Hirayama, Hirokatsu; Takamura, Yoshihide; Nishihara, Katsuya; et al.

JAEA-Research 2013-049, 129 Pages, 2014/03

JAEA-Research-2013-049.pdf:15.5MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Plant (NPP), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. In recent years, technologies for autonomous unmanned helicopters (AUHs) have been developed and applied to natural disasters. In expectation of the application of the AUHs to aerial radiation monitoring, we had developed a remote radiation monitoring system. Then, we measured the radiation level by using unmanned helicopter in soil contaminated areas by radioactive cesium emitted from the NPP to evaluate ambient dose-rate distribution around the areas and to investigate the decontamination effect by the measurements before and after decontamination treatment. Here, we reports on the measurement technique and the result.

JAEA Reports

Research for spectroscopy of fuel debris using superconducting phase transition edge sensor microcalorimeter; Measurement experiment and simulated calculation (Joint research)

Takasaki, Koji; Yasumune, Takashi; Onishi, Takashi; Nakamura, Keisuke; Ishimi, Akihiro; Ito, Chikara; Osaka, Masahiko; Ono, Masashi*; Hatakeyama, Shuichi*; Takahashi, Hiroyuki*; et al.

JAEA-Research 2013-043, 33 Pages, 2014/01

JAEA-Research-2013-043.pdf:13.81MB

In the Fukushima Daiichi Nuclear Power Plant, it is assumed that the core fuels melted partially or wholly, and the normal technique of accounting for a fuel assembly is not applicable. Therefore, it is necessary to develop the transparent and rational technique of accounting in the process of collection and storage of fuel debris. In this research, an application of the superconducting phase Transition Edge Sensor microcalorimeter (TES microcalorimeter) is studied for the accounting of nuclear materials in the fuel debris. It is expected that the detailed information of nuclear materials and fission products in fuel debris is obtained by using a high-resolution characteristic of TES microcalorimeter. In this report, the principle of TES microcalorimeter, the measurement experiment using TES in JAEA, and the simulated calculation using the EGS5 code system are summarized.

Journal Articles

Radiation monitoring using an unmanned helicopter in the evacuation zone around the Fukushima Daiichi Nuclear Power Plant

Sanada, Yukihisa; Kondo, Atsuya*; Sugita, Takeshi*; Nishizawa, Yukiyasu; Yuki, Yoichi*; Ikeda, Kazutaka*; Shoji, Yasunori*; Torii, Tatsuo

Exploration Geophysics, 45(1), p.3 - 7, 2013/11

 Times Cited Count:18 Percentile:24.46(Geochemistry & Geophysics)

The Great East Japan Earthquake on March 11, 2011 generated a series of large tsunami waves that resulted serious damage to the Fukushima Daiichi Nuclear Power Plant (NPP) and a large amount of radioactive materials were discharged from the NPP to the environment. In recent years, technologies for an unmanned helicopter have been developed and applied to various fields. In expectation of the application of the unmanned helicopter to airborne radiation monitoring, we had developed a radiation monitoring system. Then, we measured the radiation level by using unmanned helicopter in soil contaminated areas by radioactive cesium emitted from the NPP to evaluate ambient dose-rate distribution around the areas. Here, we reports on the measurement technique and the result.

Journal Articles

Enhanced analysis methods to derive the spatial distribution of $$^{131}$$I deposition on the ground by airborne surveys at an early stage after the Fukushima Daiichi Nuclear Power Plant accident

Torii, Tatsuo; Sugita, Takeshi*; Okada, C. E.*; Reed, M. S.*; Blumenthal, D. J.*

Health Physics, 105(2), p.192 - 200, 2013/08

 Times Cited Count:27 Percentile:3.65(Environmental Sciences)

In March 2011 the second largest accidental release of radioactivity in history occurred at the Fukushima Daiichi Nuclear Power Plant following a magnitude 9.0 earthquake and subsequent tsunami. Teams from the US Department of Energy National Nuclear Security Administration Office of Emergency Response performed aerial surveys to provide initial maps of the dispersal of radioactive material in Japan. The initial results from the surveys did not report the concentration of iodine-131 ($$^{131}$$I). This work reports on analyses performed on the initial survey data by a joint Japan-US collaboration to determine $$^{131}$$I ground concentration. As a result of this analysis, although the analytical results show a high concentration of $$^{131}$$I northwest of the NPP, consistent with the previously reported radioactive cesium ($$^{134}$$Cs and $$^{137}$$Cs) deposition, the $$^{131}$$I deposition shows a significant concentration south of the plant which is not represented in the radioactive cesium map.

JAEA Reports

Investigation of radionuclide distribution using aircraft for surrounding environmental survey from Fukushima Dai-ichi Nuclear Power Plant

Torii, Tatsuo; Sanada, Yukihisa; Sugita, Takeshi; Kondo, Atsuya*; Shikaze, Yoshiaki; Takahashi, Masaki; Ishida, Mutsushi; Nishizawa, Yukiyasu; Urabe, Yoshimi

JAEA-Technology 2012-036, 182 Pages, 2012/12

JAEA-Technology-2012-036.pdf:41.89MB

We carried out aerial radiation monitoring (ARM) of all Japan area in order to investigate the influence of the radio cesium which was emitted into the atmosphere by disaster of the Fukushima Dai-ichi Nuclear Power Plant of Tokyo Electric Power Co., Inc.. AMS can measure a $$gamma$$ ray quickly by flight from 300 m height above the ground. Moreover, ARM has an advantage which can grasp self-possessed quantity distribution of an air dose rate and radioactive cesium in "field", and is visually intelligible. Although there were apparatus and the technique of ARM in our country, sufficient preparations for wide area monitoring were not made. Therefore, it fixed based on the method of the U.S. Department of Energy (DOE) about the method of the conversion to all radiation dose, and the conversion method to radiocesium deposition and the method of mapping. It is possible to discriminate from a background (cosmic-ray, self-contamination and natural nuclides) at the time of western-part-of-Japan measurement by improving of the method in parallel to data acquisition. By this monitoring, it was able to check about the distribution situation of the air dose rate of the Japanese whole region, or the radioactive cesium deposition. Here, the measurement technique and a result are described.

Journal Articles

Distribution of radioactive cesium measured by aerial radiation monitoring

Sanada, Yukihisa; Kondo, Atsuya; Sugita, Takeshi; Torii, Tatsuo

Hoshasen, 38(3), p.137 - 140, 2012/12

We have measured the ambient dose-rate and the deposition amount of radioactive cesium by using four helicopters in the whole area of Japan to investigate the influence of the radioactivity that released in the atmosphere due to the disaster of the Fukushima Dai-ichi NPP (Nuclear Power Plant), Tokyo Electric Power Company (TEPCO), caused by the Tohoku-Pacific Ocean Earthquake and tsunami on March 11, 2011. We report on the measurement technique and the result.

Journal Articles

Gas control measures taken during deep shaft excavation

Nago, Makito*; Hagihara, Takeshi*; Minamide, Masashi*; Motoshima, Takayuki*; Jin, Kazumi; Kudo, Hajime; Sugita, Yutaka; Miura, Yoichi*

Dai-49-Kai Zenkoku Kensetsugyo Rodo Saigai Boshi Taikai Kenkyu Rombunshu (CD-ROM), p.77 - 80, 2012/10

This paper presents measures against gas emission during deep shaft excavation in the Horonobe Underground Research Laboratory Project (Horonobe URL Project). The gas control measures taken in the Horonobe URL Project include the following: (1) determination of the amount of methane contained in surrounding strata and groundwater, and gas concentration based on preliminary investigations, (2) determination of the specifications of fans, dust collectors, and ducts through ventilation network analysis (simulation), (3) reduction of methane gas emission through the use of waterproofing grout, (4) prohibition on the use of internal-combustion engine and the adoption of explosion-proof equipment, (5) development of methane gas control system, and (6) monitoring of methane gas emission. (3) to (6) described above are performed daily in the safety management activities and described in detail in this paper. The ventilation and eastern access shafts have currently reached a depth of 290 m and 250 m, respectively. The emission of methane gas has been observed to rise 0.3 % to 1.3 % in the fault zone, and it is controlled appropriately according to the gas control measures described above. As the measure to reduce the methane gas concentration, monitoring is confirmed to be effective.

Journal Articles

Distribution of dose-rates and deposition of radioactive cesium by the airborne monitoring surveys

Torii, Tatsuo; Sanada, Yukihisa; Sugita, Takeshi; Tanaka, Kei*

Nippon Genshiryoku Gakkai-Shi, 54(3), p.160 - 165, 2012/03

no abstracts in English

Journal Articles

Migrating source of energetic radiation generated by thunderstorm activity

Torii, Tatsuo; Sugita, Takeshi; Kamogawa, Masashi*; Watanabe, Yasuyuki*; Kusunoki, Kenichi*

Geophysical Research Letters, 38(24), p.L24801_1 - L24801_5, 2011/12

 Times Cited Count:31 Percentile:19.23(Geosciences, Multidisciplinary)

We identify a migrating source of high energy radiation, lasting for several minutes, attributed to thunderstorm activities through the observations of radiation, atmospheric electric field, and meteorological radar echoes at several points. Our findings indicate that the energetic radiation is emitted continuously from a downward hemispherical surface without lightning, the bottom of which is about 300 m above sea level, and this source of radiation moves from north to south above the observation site at a speed of about 7 m/s. The radiation source probably moves along with the negatively charged region of the cloud at the height of around 1 km, because the estimated migration of the radiation source is consistent with the observed movement of atmospheric electric field variation between ground-based observation sites and with the wind speed and direction at about 1 km altitude. This movement implies that the intensive electric field produced by the charged region in the thundercloud generates a radiation source. In addition, our results suggest that the low altitude of radiation source is related to no lightning activity during the energetic radiation emission.

Journal Articles

Full-scale experimental study on mechanical behavior of a clay plug under HLW disposal conditions

Sasakura, Takeshi*; Masumoto, Kazuhiko*; Toida, Masaru*; Fujita, Tomoo; Sugita, Yutaka

Proceedings of 9th International Conference on Geo-environmental Engineering (GEE 2010), p.47 - 56, 2010/05

High level radioactive waste is to be vitrified, and after some period of storage for cooling, put into engineered barriers such as metal canister, overpack and buffer material, and finally disposed of in the stable geology at the depth of 300 m or deeper to isolate from human environment for a long period of time in Japan. The geological repository consists of surface facilities and subsurface facilities; the later, mainly consists of tunnels for transportation and waste emplacement, will be closed using sealing technologies such as backfilling, plugging, and grouting after emplacement of the waste to prevent seepage of radionuclides for a long period of time. Effectiveness of these sealing technologies, however, has not been well demonstrated in-situ worldwide, and the technologies may be considered in the stage of research and development. Therefore, in this paper, the in-situ tunnel sealing test performed at Canada to demonstrate the effectiveness of the plug under crystalline rock environment was overviewed focusing on the plug. Then behavior of the plug, particular of mechanical behavior, during sealing tests, observation result of dismantled plug were reviewed and points to be addressed for establishing the clay plug technology were identified. Because the procedure of this tunnel sealing test and hydraulic sealing performance of the plug has already been precisely reported by Fujita et al. (2007), outline of the test is briefly summarized and mechanical behavior of the plug was focused. As a result, effectiveness of conventional construction technology of a plug was shown, the behavior of a plug during the pressurization test was clarified and important points to be addressed for establishing the clay plug technology were identified.

Journal Articles

Gradual increase of energetic radiation associated with thunderstorm activity at the top of Mt. Fuji

Torii, Tatsuo; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*

Geophysical Research Letters, 36(13), p.L13804_1 - L13804_4, 2009/07

 Times Cited Count:34 Percentile:21.03(Geosciences, Multidisciplinary)

Fluctuations of energetic radiation that seemed to be caused by a summer thunderstorm were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy $$gamma$$ rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the energetic electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge.

Journal Articles

Observation of the energetic radiation associated with a thunderstorm activity at the top of Mt. Fuji

Torii, Tatsuo; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*

Taiki Denki Gakkai-Shi, 3(1), p.111 - 112, 2009/00

Fluctuations of energetic radiation that were seemed to be caused by a summer thunderstorm activity were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy $$gamma$$ rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the runaway electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge.

Journal Articles

Observation of energetic radiation associated with winter thunderstorm activity

Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*

Hoshasen, 34(1), p.47 - 51, 2008/01

$$gamma$$-ray dose-rate increase associated with thunderstorm activities was observed on the ground in winter. To investigate the fluctuation profile during winter thunderstorms, the energetic radiation was measured by using four set of radiation detectors (LPRCs) which consist of four long proportional counters (2.5 m in length; 10 cm in diameter). These LPRC have a different response characteristic for the incident particle by mounting shield covers. It was also compared with the result measured at the same time by the environmental radiation monitors adopting an NaI scintillator / ionization chamber as a detector. Moreover, the electric field was measured at the same site by using a field mill. In the observation from December, 2006 to February, 2007, the count-rate fluctuation which seem to originate from thunderstorm activity observed by the LPRCs.

Journal Articles

Fluctuation of radiation dose-rate during winter thunderstorm

Torii, Tatsuo; Okuyama, Shinichi; Nozaki, Tatsuo; Okubo, Koichi; Sugita, Takeshi*; Muraki, Yasushi*

Chimondai Ni Yoru Saiensu; Kyokugen Enerugi Uchubutsuri Kara Chikyukagaku Made, p.211 - 217, 2008/00

The dose rate of the $$gamma$$-rays increases in association with the activities of the thunderstorm. They were observed on the ground in the winter season of Japan. In addition to the measurement by the environmental radiation monitors set up around the fast breeder reactor, Monju, the radiation detectors were prepared which consist of the long proportional counters. The results were compared with the results measured at the same time by the environmental radiation monitors. The following two types of the radiation enhancements have been found during the winter thunderstorm activities; the gradual variation of photon intensity with energy up to a few MeV, and the burst type of the radiation that is attributed to the injection of high energy photons with the energy over 10 MeV. In this paper, we present the observed results during winter thunderstorms, and mention the runaway breakdown produced by the incidence of energetic radiation into thunderclouds.

Journal Articles

Observation of the gradual increases and bursts of energetic radiation in association with winter thunderstorm activity

Torii, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*

Proceedings of 30th International Cosmic Ray Conference (ICRC 2007), Vol.1, p.677 - 680, 2008/00

The dose rate increases of the $$gamma$$-rays were observed on the ground in the winter season of Japan. To investigate the profile of the radiations during the winter thunderstorms, a four set of the radiation detectors was prepared which consists of the long proportional counters. These detectors have different characteristics of the response for the incident particle energies by mounting different thick shielding covers. Those results were compared with the results measured at the same time by the environmental radiation monitors set up around a nuclear power facility. Electric field was also measured by using a field mill. As a result, the following two types of the radiation enhancements have been found during the winter thunderstorm activities; the gradual variation of photon intensity with energy of a few MeV, and the burst type of the radiation that are attributed to the injection of high energy photons with the energy over 10 MeV.

Journal Articles

Generation of runaway electrons by atmospheric radionuclides in a thunderstorm electric field

Torii, Tatsuo; Sugita, Takeshi*

Taiki Denki Gakkai-Shi, 2(1), p.105 - 106, 2008/00

The influence of runaway electron generation by atmospheric radionuclides in a thunderstorm electric field is examined. The behavior of radiation emitted by radon, thoron and their decay products in the electric field was analyzed by Monte Carlo calculations. The results showed that a large amount of electron-ion pairs are produced in air when the electric field intensity exceeds 250 kV/m at the altitude of 2 km (about 320 kV/m at the sea-level equivalent pressure). Furthermore, the influence of the resuspension of fallout nuclides was analyzed because lightning activity after the Chernobyl nuclear accident increased in central Sweden where a considerable amount of nuclides fell. It is shown that, similar to natural radioactive nuclides, these nuclides significantly influence the ionization within the thundercloud.

Journal Articles

Incorporating the electromagnetic field in the EGS5 code

Torii, Tatsuo; Sugita, Takeshi*

KEK Proceedings 2007-5, p.43 - 49, 2007/11

74 (Records 1-20 displayed on this page)