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Mori, Airi; Ishizaki, Azusa; Futemma, Akira; Tanabe, Tsutomu; Wada, Takao; Kato, Mitsugu; Munakata, Masahiro
Hoken Butsuri (Internet), 54(1), p.45 - 54, 2019/04
Kato, Tomoko; Fukaya, Yukiko*; Sugiyama, Takeshi*; Nakai, Kunihiro*; Oda, Chie; Oi, Takao
JAEA-Data/Code 2019-002, 162 Pages, 2019/03
JAEA-Data-Code-2019-002.pdf:2.78MB
The radioactive waste generated from Fukushima Daiichi nuclear power station (FDNPS) accident have features such as wide range of radioactivity level (from low to high) and huge amount etc. It would be necessary for the waste from the FDNPS accident to develop suitable disposal concept and to be disposed safely and reasonably. When considering such appropriate disposal concepts in site-generic phase, it is necessary to appropriately develop models and parameters depending on the disposal concepts, such as disposal depth and specification of engineered barrier. In addition, it is desirable to evaluate the safety of repository with common models and parameters independent on the disposal concepts. In the safety assessment of disposal, it is useful to show the difference in performance of repository with "dose" as an indicator of safety assessment. Biosphere model and parameter set and flux-to-dose conversion factors calculated using them are originally dependent on the disposal concepts. However, the biosphere models and the parameter set in safety assessment of near-surface disposal, sub-surface disposal and geological disposal are prepared in each case, and are different according to the age and purpose of the discussion. In this study, an example of biosphere model and parameter-set of groundwater sceinario commonly applicable to various disposal concepts were shown, to calculate flux-to-dose conversion factors, as common indicators independent to disposal concept. And, a set of flux-to-dose conversion factors was also calculated by using the commonly available biosphere model and parameter set. By applying the flux-to-dose conversion factors, it is possible to compare the performance of disposal concepts to the waste generated from FDNPS accident, focusing on the parts depending on the disposal concepts.
Mori, Airi; Tanabe, Tsutomu; Wada, Takao; Kato, Mitsugu
JAEA-Technology 2017-006, 38 Pages, 2017/03
JAEA-Technology-2017-006.pdf:2.98MB
Large quantities of radioactive materials were released into the environment as a result of the Fukushima Daiichi Nuclear Power Station accident. Residential areas and forest areas near the power station were contaminated with the radioactive materials. Outside of the houses, schools and the other buildings are being decontaminated by national authority and local government. On the other hand, the materials (such as walls, floors, or windows) which constitute the houses are not decontaminated officially. In order to prepare decontamination methods that can be applied easily, we conducted examinations of decontamination for various materials in houses. Fibrous materials, woods, glasses, concretes, plastics, vinyl chloride materials, metals and synthetic leathers were used in our examinations. These materials were collected from houses in difficult-to-return zone, and were contaminated by radioactive materials released by the accident. Dry methods (suction, wiping, adsorption and peelable coating), wet methods (wiping, brushing, polishing and washing) and physical method (peeling of materials) were used for decontamination. As a result of our examinations, materials with low water permeability, such as glasses, concretes, vinyl chloride materials and metals, were able to be decontaminated efficiently (about 90% reduction) by using wet methods. Materials with high water permeability like woods were relatively well decontaminated by peelable coating (about 60%-70% reduction). In addition to the examination described above, the difference of contamination reduction effect between chemical properties of detergents and the effect of rubbing of peelable coating were also examined. Finally, the most effective method was summarized based on these examinations.
Kato, Mitsugu; Tanabe, Tsutomu; Umezawa, Katsuhiro; Wada, Takao
JAEA-Technology 2016-004, 129 Pages, 2016/03
JAEA-Technology-2016-004.pdf:20.42MB
After the Fukushima-Daiichi Nuclear Power Station accident, widespread contamination by radioactive materials occurred. Thus, decontamination work have been developed because of reducing air dose rate. Of this, in order to examine decontamination effect about gravel which cover sites of houses, communal facilities and cemeteries, and about ballast laid on a track, JAEA examined a decontamination test by physical plural methods. The objective of this testing is to establish rational and high effective decontamination methods to decontaminate each different gravel of materials and the shape, using the equipment which have possibility of the decontamination effect by trituration or blast. From the test results, applicability of the decontamination method depending on a characteristic of the gravel and the decontamination effect (reduction rate) are confirmed. There are various characteristics with the thing said to be gravel. It is confirmed that one decontamination method cannot be applied to all types of gravel. Furthermore, it is confirmed that there is great variability among individual polluted condition in the gravel gathered from the same place. Therefore, it is important to measure the degree of pollution so that a measurement error becomes as little as possible. For example, to measure plural points of the measurement side and keeping the height of measurement constant.
Arifi, E.*; Ishimatsu, Koichi*; Iizasa, Shinya*; Namihira, Takao*; Sakamoto, Hiroyuki*; Tachi, Yukio; Kato, Hiroyasu*; Shigeishi, Mitsuhiro*
Construction and Building Materials, 67(Part B), p.192 - 196, 2014/09
Times Cited Count：5 Percentile：25.91(Construction & Building Technology)The Fukushima Dai-ichi Nuclear Plant accident has resulted in a large amount of radioactively contaminated concrete. The possible application of the pulsed power discharge to reduce the amount of contaminated concrete as radioactive waste was investigated. The contaminated concrete was decontaminated by separating contaminated matrix from uncontaminated coarse aggregate under pulsed power discharge process. In this study, a stable Cs isotope was used to simulate radioactively contaminated concrete. As a result, while the volume of reclaimed aggregate from contaminated concrete could be reproduced was up to 60%, nevertheless Cs detected in the reclaimed aggregate was only approximately 3%. Thus most of the Cs were dissolved in water during the discharge process. It is expected that the pulsed power could reduce the contaminated concrete waste by reusing aggregate. Further investigations are requested to test the applicability of this method under the realistic conditions close to the actual waste.
Kato, Nobuyoshi*; Tsusaka, Kimikazu; Nago, Makito*; Yamagami, Masahito*; Matsubara, Makoto*; Shigehiro, Michiko*; Aizawa, Takao*; Kamemura, Katsumi*
Chishitsu To Chosa, (139), p.17 - 22, 2014/04
no abstracts in English
Shobu, Nobuhiro; Kato, Masatoshi*; Takao, Tomoe*; Terashima, Daisuke*; Tanaka, Yoshie*; Shirasu, Hisanori*; Amazawa, Hiroya; Koibuchi, Hiroto; Nakata, Hisakazu
JAEA-Review 2013-028, 175 Pages, 2013/12
JAEA-Review-2013-028.pdf:10.13MB
JAEA has promoted near surface disposal project for low-level radioactive wastes generated from research, industrial and medical facilities. JAEA has carried out public information about the project. When some town meetings are held toward mutual understanding with the public more detailed and clear explanations for safety management of the project are needed especially. Therefore, the information provision method to make the public understand should be reviewed. Moreover, a survey should be carried out in order to get a sense of what the public knows, what it values and where it stands on nuclear energy and radiation issues, because the social environment surrounding nuclear energy and radiation issues has changed as a result of the accident at the Fukushima on March 11, 2011. This review clarified the points to keep in mind about public information on the project, and that public recognition or understanding toward nuclear energy and radiation was changed before and after the accident.
Kato, Tomoko; Suzuki, Yuji*; Oi, Takao
Hoken Butsuri, 44(1), p.72 - 79, 2009/03
It is difficult to acquire all of biosphere parameters at the repository site because we have to deal with several hundreds of the parameters in one calculation case of the biosphere assessment. Before site-specific activities, it is important to develop the data acquisition methodology of biosphere parameters applicable to any proposed repository site. In this study, we developed the methodology for identification of the priority of the parameters for the effective data acquisition of biosphere parameters at the site. First of all, flow diagram was constructed to evaluate the availability of the existing generic biosphere dataset. We found that it was effective for the data acquisition at the site to focus on the element-specific parameters with the existing dataset. Secondly, we identified the priority of the data acquisition for element-specific parameters at the site, with considering the variation of radiation dose by combining the significant element-specific parameters. As a result, we identified the availability of the existing generic biosphere dataset and the priority on data acquisition of the element-specific parameters of key radionuclides in the safety assessment of geological disposal that should be acquired at the site. This priority list would be useful for effective data acquisition at the site.
Oi, Takao; Kato, Tomoko; Kawachi, Susumu; Kawamura, Makoto
JAEA-Research 2008-014, 14 Pages, 2008/03
JAEA-Research-2008-014.pdf:2.93MB
The method contributing to the improvement of confidence and the systematization of the various information and knowledge under the responsibility of each researcher has examined. As a result, "a systematic compilation method to exhibit the level of the confidence on the assessments" has been developed based on the approach of the international quality management system. It is possible to manifest the aims, intention, contents, approach and process of the study by compiling and presenting the results of the studies using this method. In addition, transparency and traceability would be shown and the adequacy of the obtained result would be claimed by researcher through the conformity assessment for the result of the study. These results would contribute the understanding of reader and improvement of confidence.
Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.
Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10
J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.
Ito, Takashi; Asano, Hiroyuki; Morishita, Takatoshi; Ao, Hiroyuki; Tanaka, Hirokazu*; Naito, Fujio*; Kato, Takao*; Takasaki, Eiichi*
Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1517 - 1519, 2007/06
The high-power conditioning of the three DTL tanks for the J-PARC has been started in October 2006. The design rf peak-power levels for beam acceleration of the tanks are about 1.1MW (DTL1), 1.2MW (DTL2) and 1.0MW (DTL3), respectively. As a result of the conditioning, we have achieved that the rf power levels are about 1.3MW, 1.45MW and 1.23MW of which are 1.2 times the power levels of the desired one (the pulse length is 650
s and the pulse repetition is 25Hz). During the linac beam commissioning, the DTLs can keep the required rf power stable now.
Inagaki, Manabu; Kato, Tomoko; Yoshida, Hideji*; Oyamada, Kiyoshi*; Fukaya, Yukiko*; Suzuki, Yuji*; Oi, Takao
JAEA-Research 2007-029, 81 Pages, 2007/03
JAEA-Research-2007-029.pdf:10.88MB
The project of high-level radioactive waste disposal is in activity for the site selection of HLW disposal facility and the performance assessment should be more site-specific rather than site-generic, where the applicability of the achievement of site-generic study such as second progress report (H12) to the site specific is to be clarified. In the same way, it is necessary for biosphere assessment to incorporate the site specific condition to the model. The exposure pathway or concentration of the radio nuclides should be determined according to the site specific geological condition, for example. In this paper, following topics have been selected to start the study to reflect specific geological condition to the biosphere modeling. (1) The literature survey of international and national approaches and issues relating to the treatment of GBIs within biosphere assessments, (2) To develop methodology to estimate the release point of the deep groundwater to the shallow accessible groundwater. (3) To prepare information to estimate water balance this is, in turn, necessary to assess the dilution and/or dispersion of the radionuclides in the shallow accessible groundwater body.
Ito, Takashi; Asano, Hiroyuki; Morishita, Takatoshi; Yamazaki, Yoshishige; Tanaka, Hirokazu*; Naito, Fujio*; Kato, Takao*; Takasaki, Eiichi*
Proceedings of 23rd International Linear Accelerator Conference (LINAC 2006) (CD-ROM), p.740 - 742, 2007/00
For the J-PARC (Japan Proton Accelerator Research Complex) linac, an SDTL (Separated type Drift Tube Linac) is used to accelerate an H
ion beam from 50 MeV to 191 MeV. We have measured the RF characteristics of the SDTL tanks and adjusted the field distribution. The measured Q value was above 90% of an ideal SUPERFISH value. Furthermore the field distribution was adjusted within 
1% for all the tanks.
Ito, Takashi; Asano, Hiroyuki; Morishita, Takatoshi; Yamazaki, Yoshishige; Naito, Fujio*; Takasaki, Eiichi*; Yoshino, Kazuo*; Tanaka, Hirokazu*; Kato, Takao*; Kabeya, Zenzaburo*; et al.
Proceedings of 23rd International Linear Accelerator Conference (LINAC 2006) (CD-ROM), p.782 - 784, 2007/00
Three DTL tanks and 32 SDTL tanks for the Japan Proton Accelerator Research Complex (J-PARC) were assembled at KEK site. After the assembling, the high-power conditioning of the DTL1 and 12 SDTL tanks and the beam acceleration test for the DTL1 ware carried out. And then all the DTL and SDTL tanks have to be transported form KEK to JAEA. In order to confirm the effect of the transportation to the drift tube alignment, we measured the displacement of the drift tube positions before and after the transportation by using a prototype cavity. As a result of the test, the measured displacement of the drift tubes by the transportation was less than 0.02mm which is consistent in the measurement accuracy. Based on this result, all the DTL and SDTL tanks were transported form KEK to JAEA.
Miyahara, Kaname; Yoshikawa, Hideki; Oi, Takao; Shibata, Masahiro; Sawada, Atsushi; Sasamoto, Hiroshi; Iijima, Kazuki; Maekawa, Keisuke; Kawamura, Makoto; Kato, Tomoko; et al.
JAEA-Review 2006-015, 29 Pages, 2006/03
JAEA-Review-2006-015.pdf:4.58MB
This report is to outline a 5-year plan of research and development (R&D) for performance assessment of geological disposal of high-level radioactive waste in JAEA. This 5-year plan is based on JAEA's mid-term plan which follows the R&D policy specified in "Framework for Nuclear Energy Policy" issued by Japan Atomic Energy Commission. Moreover, research plans for safety regulation issued by Nuclear Safety Commission of Japan should be taken into account. The contents of this 5-year plan follows a framework of R&D issues for performance assessment field established in "the R&D map", i.e. the mid and long term R&D plan for geological disposal of high-level radioactive waste, developed by JNC (predecessor of JAEA) and other relevant R&D organizations. In each research plan, objectives based on the necessity and the significance of the research plan are clarified in the section of "Objectives and the past progresses", with summarizing the progresses of H12: Project to establish the scientific and technical basis for HLW disposal in Japan (Second Progress Report), and H17: Development and management of the technical knowledge base for the geological disposal of HLW (H17 report). In addition, next five year plan is described in the section of "5-year plan (up to Fiscal year Heisei-22)".
Suzuki, Yuji*; Kato, Tomoko; Makino, Hitoshi; Oi, Takao
JAEA-Data/Code 2006-011, 277 Pages, 2006/03
JAEA-Data-Code-2006-011.pdf:23.39MB
The project to establish a technical basis for HLW disposal in Japan (H12) has used "reference biosphere" methodology. The radiation dose which was an index as a basis of the safety assessment was calculated. (In fact, the flux-to-dose conversion factors were calculated as coefficient reduced flux of radionuclide caused by geological disposal to radiation dose in biosphere.) And then, ICRP has introduced the new system for radiological protection in the publication 60 published in 1990. New regulations in Japan have been issued in 2001 and it defines new dose conversion factors of ingestion and inhalation as effective dose coefficients based on the publication 60. And so, nuclides for biosphere assessment of HLW disposal, the flux-to-dose conversion factors for biosphere assessment were calculated based on the new regulations. On the other hands, recent safety assessment on a waste of geological disposal equivalent in radioactive waste containing transuranic (TRU) nuclide was carried out the safety assessment based on the biosphere assessment model constructed by the methodology other than the reference biosphere. "Co-disposal concept" disposed of by also juxtaposing TRU waste with geological disposal site of high-level radioactive waste, was examined the geological disposal of TRU waste, and the consistency of models and assessment system in the geological disposal of HLW and TRU waste would have been required. Moreover, the environmental conditions in future various biosphere based on climatic change are considered, the importance of discussion considering the variation of the biosphere system has been indicated. The data set for appropriate models that should be considered in geological disposal safety assessment of TRU waste was also set, and flux-to-dose conversion factors were calculated for the new regulation based on the same concept and models as HLW disposal.
Ito, Takashi; Asano, Hiroyuki*; Morishita, Takatoshi; Kato, Takao*; Takasaki, Eiichi*; Tanaka, Hirokazu*; Yoshino, Kazuo*; Naito, Fujio*
Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.242 - 244, 2005/07
The third Drift Tube Linac (DTL3) is adopted for 37MeV-50MeV part of high intensity proton linac for Japan Proton Accelerator Research Complex(J-PARC). DTL3 consists of 26 full drift tubes, 2 half drift tubes and 26 post-couplers. As a result of tuning of the accelerating field of the DTL3, the resonant frequency was adjusted to 324MHz and the average accelerating field distribution was adjusted within 1%.
Ito, Takashi; Asano, Hiroyuki*; Morishita, Takatoshi; Kato, Takao*; Takasaki, Eiichi*; Tanaka, Hirokazu*; Naito, Fujio*
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.344 - 346, 2004/08
no abstracts in English
Oba, Toshihiro; Suetsugu, Hidehiko*; Yano, Masaya*; Kato, Chiaki; Yanagihara, Takao
JAERI-Tech 2002-082, 47 Pages, 2003/01
JAERI-Tech-2002-082.pdf:1.87MB
The demonstration test for evaluating reliability of the acid recovery evaporator at Rokkasho Reprocessing Plant has been carried out at JAERI. For the nondestructive measurement of the thickness of heat transfer tubes of the acid recovery evaporator in corrosion test, we have developed thickness measurement apparatus for heat transfer tubes by ultrasonic immersion method with high resolution. The ultrasonic prove in a heat transfer tube can be moved vertically and radially. The results obtained by this apparatus coincident well with those obtained by a destructive method using an optical microscope.
Hayashizaki, Noriyosu*; Ao, Hiroyuki; Hasegawa, Kazuo; Yamazaki, Yoshishige; Ikegami, Masanori*; Kato, Takao*; Paramonov, V.*
Proceedings of 21st International Linac Conference, p.234 - 236, 2003/00
The normal conducting coupled-cavity linac with the Annular Coupled Structure (ACS) is adopted for 190-400 MeV part of high intensity proton linac for the JAERI/KEK Joint Project. The operating frequency is 972 MHz and the 23 modules will be constructed. The basic configuration is based on that investigated for L-band (1296 MHz) in the previous Japan Hadron Project research. However, the structure design is revised and optimized in order to meet requirements of reliability, operation efficiency and cost reduction for the newly proposed Joint Project. As the results of development, the transverse dimensions of the ACS tank are reduced sufficiently with the improvement in RF characteristics. The structure segmentation and essential points of the design are described.
