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Journal Articles

Tolerance of spin-Seebeck thermoelectricity against irradiation by swift heavy ions

Okayasu, Satoru; Harii, Kazuya*; Kobata, Masaaki; Yoshii, Kenji; Fukuda, Tatsuo; Ishida, Masahiko*; Ieda, Junichi; Saito, Eiji

Journal of Applied Physics, 128(8), p.083902_1 - 083902_7, 2020/08

Journal Articles

Activity report of the task group of radiation protection about wastes containing natural radioactive nuclides

Saito, Tatsuo; Kobayashi, Shinichi*; Zaitsu, Tomohisa*; Shimo, Michikuni*; Fumoto, Hiromichi*

Hoken Butsuri (Internet), 55(2), p.86 - 91, 2020/06

Safety cases for disposal of uranium bearing waste and NORM with uranium has not yet been fully developed in Japan, because of safety assessment of extraordinary long timespan and uncertainty in unexpected incidents with uncompleted radon impact evaluation measures arising from uranium waste disposal facility in far future. Our task group of radiation protection for wastes with natural radioactive nuclides studied some safety cases with disposal of uranium bearing waste and NORM in terms of nuclides, U-235, U-238 and their progenies, and comprehensively discussed the current state of their disposal in comparison to the ideas of international organizations such as ICRP and IAEA. We developed our ideas for long term uncertainty and radon with the knowledge of experts in each related area of direction, repeating discussions, focusing out the orientation of each directions, and outlined the recommendations with our suggestions of solving important issues in the future to be addressed.

Journal Articles

Hard X-ray photoelectron spectroscopy study of Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$

Kobata, Masaaki; Yoshii, Kenji; Fukuda, Tatsuo; Kawasaki, Ikuto; Okane, Tetsuo; Yamagami, Hiroshi; Yaita, Tsuyoshi; Harii, Kazuya; Ieda, Junichi; Okayasu, Satoru; et al.

JPS Conference Proceedings (Internet), 30, p.011192_1 - 011192_6, 2020/03

High energy X-ray photoelectron spectroscopy (HAXPES) measurements were carried out for the Spin Seebeck system Pt/Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$(YIG). This system was found to show anomalous Hall effect, possible due to the formation of intermetallic compounds between Fe$$^{3+}$$ and Pt. To reveal this possibility, we have measured the Fe 1s photoelectron peaks by using HAXPES. It was found that the Fe ions consist of Fe$$^{3+}$$ in YIG and metallic Fe. The formation of the metallic state is consistent with the proposed origin of the anomalous Hall effect. Other spectra such as Pt 4f will be presented at the conference.

Journal Articles

Utilization of $$^{134}$$Cs/$$^{137}$$Cs in the environment to identify the reactor units that caused atmospheric releases during the Fukushima Daiichi accident

Chino, Masamichi; Terada, Hiroaki; Nagai, Haruyasu; Katata, Genki; Mikami, Satoshi; Torii, Tatsuo; Saito, Kimiaki; Nishizawa, Yukiyasu

Scientific Reports (Internet), 6, p.31376_1 - 31376_14, 2016/08

 Times Cited Count:22 Percentile:3.08(Multidisciplinary Sciences)

Journal Articles

Evaluation of ambient dose equivalent rates influenced by vertical and horizontal distribution of radioactive cesium in soil in Fukushima Prefecture

Malins, A.; Kurikami, Hiroshi; Nakama, Shigeo; Saito, Tatsuo; Okumura, Masahiko; Machida, Masahiko; Kitamura, Akihiro

Journal of Environmental Radioactivity, 151(Part 1), p.38 - 49, 2016/01

AA2015-0160.pdf:0.87MB

 Times Cited Count:30 Percentile:11.66(Environmental Sciences)

The air dose rate in an environment contaminated with $$^{134}$$Cs and $$^{137}$$Cs depends on the amount, depth profile and horizontal distribution of these contaminants within the ground. This paper introduces and verifies a tool that models these variables and calculates ambient dose equivalent rates at 1 m above the ground. Good correlation is found between predicted dose rates and dose rates measured with survey meters in Fukushima Prefecture in areas contaminated with radiocesium from the Fukushima Dai-ichi Nuclear Power Plant accident. Better predictions are obtained by modeling the horizontal distribution of radioactive cesium across an area if multiple soil samples are available, as opposed to assuming a spatially homogeneous contamination distribution. Reductions seen in air dose rates above flat, undisturbed fields in Fukushima Prefecture are consistent with decrement by radioactive decay and downward migration of cesium into soil. Analysis of remediation strategies for farmland soils confirmed that topsoil removal and interchanging a topsoil layer with a subsoil layer result in similar reductions in the air dose rate.

Journal Articles

Mathematical Modeling of Radioactive Contaminants in the Fukushima Environment

Kitamura, Akihiro; Kurikami, Hiroshi; Yamaguchi, Masaaki; Oda, Yoshihiro; Saito, Tatsuo; Kato, Tomoko; Niizato, Tadafumi; Iijima, Kazuki; Sato, Haruo; Yui, Mikazu; et al.

Nuclear Science and Engineering, 179(1), p.104 - 118, 2015/01

 Times Cited Count:6 Percentile:38.07(Nuclear Science & Technology)

The prediction of the distribution and fate of radioactive materials eventually deposited at surface in the Fukushima area is one of the main objectives and expected to be achieved in an efficient manner. In order to make such prediction, a number of mathematical models of radioactive contaminants, with particular attention on cesium, on the land and in rivers, lakes, and estuaries in the Fukushima area are developed. Simulation results are examined with the field investigations simultaneously implemented. The basic studies of the adsorption/absorption mechanism of cesium and soils have been performed to shed light on estimating distribution coefficient between dissolved contaminant and particulate contaminant.

JAEA Reports

Survey on uranium bearing waste disposal facilities in foreign countries

Saito, Tatsuo; Sakai, Akihiro; Sato, Kazuhiko; Yagi, Naoto; Hata, Haruhi; Fumoto, Hiromichi*; Kawagoshi, Hiroshi; Hasegawa, Makoto

JAEA-Review 2014-021, 30 Pages, 2014/07

JAEA-Review-2014-021.pdf:4.51MB

Japan Atomic Energy Agency surveyed the reference cases for the disposal of uranium bearing waste in low activity concentration as the contents of their own category 2 waste disposal facility for the Research and Development Activities. We reviewed the concepts mentioned in IAEA and ICRP documents, reference cases of uranium bearing waste disposal in selected countries (USA, Canada, UK, France and Sweden), and the disposal styles of long-lived radioactive waste were summarized, and the action items for application to the disposal system of our country was arranged. The disposal facilities in selected countries can be classified into 2 types with the length of performance assessment period for intruder scenario. They are long term assessment type and short term assessment type. It seems that the disposal system construction in category 2 waste disposal is the most realistic since there are many precedence examples of each country. Correspondence of 2 types of these disposal facilities is useful as a reference case.

JAEA Reports

Survey on uranium bearing waste disposal facilities in European countries

Sato, Kazuhiko; Sakai, Akihiro; Hata, Haruhi; Fumoto, Hiromichi*; Kawagoshi, Hiroshi; Saito, Tatsuo; Hasegawa, Makoto

JAEA-Review 2014-006, 78 Pages, 2014/03

JAEA-Review-2014-006.pdf:4.61MB

In this paper, we report the result of survey for basic principle of safety assessment for long-lived low-level (LL-LL) waste disposal and experience of the industrial waste disposal sites for uranium bearing waste in France, UK and Sweden, following the report of survey for U.S.A. and Canada published in December 2013.

JAEA Reports

Survey on uranium bearing waste disposal facilities in North American Continent

Hasegawa, Makoto; Saito, Tatsuo; Zaitsu, Tomohisa; Sato, Kazuhiko; Sakai, Akihiro; Fumoto, Hiromichi*

JAEA-Review 2013-043, 42 Pages, 2013/12

JAEA-Review-2013-043.pdf:4.24MB
JAEA-Review-2013-043-appendix(CD-ROM).zip:10.55MB

Uranium bearing waste in Japan is not included in Category-2 radioactive waste disposal in NSCRG: F-RW-I.02 (published in August 2010, NSC Japan). Therefore, disposal of uranium bearing waste should be considered in institutionalization. In charge of the consideration, it is thought effective to refer to the proven tactics of the uranium waste disposal in overseas and the information on a safe regulatory system. Since the view of regulations and enterprises in this field are progressing day by day, renewal of the existing information of disposal of the uranium waste in each country is required. Furthermore, amendment of the U.S. federal rule aiming at safety disposal of depleted uranium is in progress. It is important to collect and arrange the latest information on the two above-mentioned points. Therefore, it visited the disposal responsible organization and regulatory agency of the disposal site of the uranium waste in the U.S. and Canada, and held institution investigations and interviews paying attention to the following four items: (1) "amendment of the U.S. 10CFR61", (2) "Safety evaluation of uranium bearing waste", (3) "Disposal site design", (4) "Stakeholder involvement".

JAEA Reports

Preliminary calculation of concentration corresponding to the dose criterion for materials, etc. in the non-controlled area

Takebe, Shinichi; Sasaki, Toshihisa; Saito, Tatsuo; Yamaguchi, Naoko

JAEA-Technology 2013-033, 87 Pages, 2013/11

JAEA-Technology-2013-033.pdf:2.49MB

Materials, etc. in a non-controlled area is, if the criteria (10microsievert per year) listed below that in "A guideline regarding treatment of materials in nuclear facilities considering the influence of fallout released from the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station", that in accordance with relevant laws and regulations, such as "Waste Disposal and Cleaning Act", effective use as a resource or be properly disposed of is required. In this paper, in order to effectively use as resources or properly disposed of the materials, etc. in a non-controlled area, radioactivity concentration of materials, etc. in you see "For clearance level specified in Radiation Hazards Prevention Law" and "Radionuclide Concentrations for Materials not Requiring Treatment as Radioactive Wastes Generated from Dismantling etc. of Reactor Facilities and Nuclear Fuel Use Facilities (in Japanese), NSC Japan, March 2005." corresponds to the dose of the above criteria the presented results have been estimated as an example.

Journal Articles

Current status of the AMS facility at the Tono Geoscience Center of the Japan Atomic Energy Agency

Kokubu, Yoko; Nishizawa, Akimitsu*; Suzuki, Mototaka*; Owaki, Yoshio*; Nishio, Tomohiro*; Matsubara, Akihiro; Saito, Tatsuo; Ishimaru, Tsuneari; Umeda, Koji; Hanaki, Tatsumi

Nuclear Instruments and Methods in Physics Research B, 294, p.43 - 45, 2013/01

 Times Cited Count:3 Percentile:67.55(Instruments & Instrumentation)

The Tono Geoscience center of JAEA installed the JAEA-AMS-TONO system at 1997. Since 1998, the system has routinely used for $$^{14}$$C-AMS. Recently, about 800 samples/y have been measured mainly for studies of neotectonics and hydrogeology in relation to research of geosphere stability for long-term Isolation of high-level radioactive waste. Under the common-use facility program, the system has also been used by researchers of universities and other institutes. In addition, $$^{10}$$Be-AMS has been developed for geochronological study. A gas ionisation detector was exchanged. As the detector has a gas absorber cell which has larger volume than the previous one, it is possible to remove $$^{10}$$B efficiently. Test measurement by using several standard samples supplied from University of California, Berkeley was performed. Ratios of $$^{10}$$Be/$$^{9}$$Be were comparable to the certified values, indicating that our system has sufficient ability to be useful to $$^{10}$$Be-AMS.

JAEA Reports

Annual report for research on long-term stability of geological environments in FY2007

Kusano, Tomohiro; Nohara, Tsuyoshi; Umeda, Koji; Ishimaru, Tsuneari; Hanamuro, Takahiro; Saito, Tatsuo; Yasue, Kenichi; Niwa, Masakazu; Shimada, Koji; Yamada, Kunimi; et al.

JAEA-Research 2009-022, 47 Pages, 2009/09

JAEA-Research-2009-022.pdf:48.94MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment, taking into account volcanism, faulting, uplift, denudation, climatic change and sea-level change in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. In fiscal year 2007, we carried out the following researches, to confirm existence of the phenomena that have influences on geological disposal system (e.g., active faulting, volcanism), and to develop the investigation techniques to reconstruct the history of these phenomena. For studies of faulting and seismic activity, we developed the investigation techniques to research distribution of crush zone, process of faulting, activity, and so on. For volcanological and geothermal studies, we developed a technique for detecting crustal magma and/or geothermal fluid in deep underground. For studies of uplift/denudation and climatic/sea-level changes, we extracted investigation techniques for landform developments and uplift rate with river terraces.

JAEA Reports

Study plan for research on long-term stability of geological environments in FY2008

Nakatsuka, Noboru; Nohara, Tsuyoshi; Umeda, Koji; Ishimaru, Tsuneari; Hanamuro, Takahiro; Saito, Tatsuo; Yasue, Kenichi; Niwa, Masakazu

JAEA-Review 2008-039, 19 Pages, 2008/09

JAEA-Review-2008-039.pdf:4.95MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment, taking into account volcanism, faulting, uplift, denudation, climatic change and sea-level change in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. During fiscal year 2008, research/prediction about the following items will be carried out. Concerning earthquake and fault movement, we continue to develop research techniques for evolutional history and activity of fault, and carry out case studies for development of effective assessment model in the fault zones will be carried out. For volcanological and geothermal studies, we are planning to provide an integrated approach for detecting crustal magma and/or geothermal fluid in deep underground using geophysical and geochemical data, and models assessing the likelihood of future volcanism and its influence on geological environment. Concerning uplift, denudation, climatic change and sea-level change, we plan to arrange research techniques for reconstruction of paleo-topography and paleo-climate, and to establish a simulation model for landform development. Concerning a general evaluation study about the long-term stability of the geological environment, information maintenance about a change of geological environment with hydrothermal activity, and development of simulation techniques for groundwater flow related by crustal movement, climatic change will be carried out. In addition, maintenance of development of analytical methods to perform the data acquisition that is necessary for these studies will be carried out.

JAEA Reports

Annual report for research on long-term stability of geological environment in FY2006

Nohara, Tsuyoshi; Umeda, Koji; Sasao, Eiji; Hanamuro, Takahiro; Saito, Tatsuo; Yasue, Kenichi; Niwa, Masakazu; Mashima, Hidehisa*; Shimada, Koji; Yamada, Kunimi; et al.

JAEA-Research 2008-062, 61 Pages, 2008/07

JAEA-Research-2008-062.pdf:39.02MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. During fiscal year 2006, we carried out the following researches, to confirm existence of the phenomena that have influences on geological disposal system, and to develop the research techniques to reconstruct the history of these phenomena. For studies of active faulting and seismic activity, we reviewed the existing techniques to research past activities and distribution of active faults (migration, extension, development process of a deformation zone). For volcanological and geothermal studies, we extracted a technique for detecting crustal magma and/or geothermal fluid in deep underground using geophysical and geochemical data, and models assessing the likelihood of future volcanism and its influence on geological environment. For studies of uplift/denudation and climatic/sea-level change, we constructed conceptual models such as landform development model.

Journal Articles

Examination of the effects of the conditions of measurement on pMC and $$delta$$$$^{13}$$C

Saito, Tatsuo; Nishizawa, Akimitsu*; Suzuki, Mototaka

JAEA-Conf 2008-005, p.157 - 160, 2008/03

no abstracts in English

Journal Articles

Present status of the JAEA-ANS-TONO

Suzuki, Mototaka; Nishizawa, Akimitsu*; Owaki, Yoshio*; Nishio, Tomohiro*; Saito, Tatsuo; Sasao, Eiji

JAEA-Conf 2008-005, p.34 - 37, 2008/03

no abstracts in English

JAEA Reports

Study plan for research on long-term stability of geological environment in FY2006

Nakatsuka, Noboru; Nohara, Tsuyoshi; Umeda, Koji; Sasao, Eiji; Saito, Tatsuo; Yasue, Kenichi

JAEA-Review 2007-047, 19 Pages, 2008/01

JAEA-Review-2007-047.pdf:2.94MB

The Japanese islands are located in the tectonically active Circum-Pacific Mobile Belt. As a result, Japan has a high frequency of earthquakes and eruptions. Special consideration is given to the long-term stability of the geological environment, taking into account volcanism, faulting, uplift, denudation, climatic change and sea-level change in Japan. Development of research/prediction technologies for geotectonic events has been carried out to evaluate the long-term stability of the geological environment in Japan. During fiscal year 2006, to confirm existence of the phenomena that have a influence on geological disposal system (e.g. active fault or magma) and to confirm that there was not the trace that the phenomena occurred in the past and to predict/evaluate possibility of the phenomena, development of the research/prediction techniques will be carried out. Concerning active fault and seismic activity, information maintenance for research of an activity history and distribution of an active fault (movement, extension, development process of a deformation zone) will be carried out. For volcanological and geothermal studies, we are planning to examine a technique for detecting crustal magma and/or geothermal fluid in deep underground using geophysical and geochemical data, and models assessing the likelihood of future volcanism and its influence on geological environment. Concerning uplift, denudation, climatic change and sea-level change, making of concept model for landform development will be carried out.

JAEA Reports

Safety demonstration test (SR-2/S2C-2/SF-1) plan using the HTTR (Contract research)

Sakaba, Nariaki; Nakagawa, Shigeaki; Takamatsu, Kuniyoshi; Takada, Eiji*; Saito, Kenji; Furusawa, Takayuki; Tochio, Daisuke; Tachibana, Yukio; Iyoku, Tatsuo

JAERI-Tech 2004-014, 24 Pages, 2004/02

JAERI-Tech-2004-014.pdf:1.06MB

Safety demonstration tests using the HTTR are in progress to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to not only the commercial HTGRs but also the research and development for the VHTR one of the Generation IV reactors. This paper describes the reactivity insertion test and coolant flow reduction test by trip of gas circulator and partial flow loss of coolant planned in 2004 with detailed test method, procedure and results of pre-test analysis. From the analytical results, it was found that the negative reactivity feedback effect of the core brings the reactor power safely to a stable level without a reactor scram.

JAEA Reports

Safety demonstration test (S1C-2/S2C-1) plan using the HTTR (Contract research)

Sakaba, Nariaki; Nakagawa, Shigeaki; Takada, Eiji*; Tachibana, Yukio; Saito, Kenji; Furusawa, Takayuki; Takamatsu, Kuniyoshi; Tochio, Daisuke; Iyoku, Tatsuo

JAERI-Tech 2003-074, 37 Pages, 2003/08

JAERI-Tech-2003-074.pdf:1.83MB

Safety demonstration tests using HTTR are now underway in order to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to research and development for the VHTR, which is one of the Generation IV reactors. The first phase of the safety demonstration tests includes reactivity insertion tests by means of control-rod withdrawal and coolant flow reduction tests by tripping the gas circulators. In the second phase, accident simulation tests will be conducted. This paper describes the plan of coolant flow reduction tests by tripping of gas circulators planned in August 2003 with detailed test method, procedure and results of pre-test analysis. The analysis results of the steady state and transient behaviours of the reactor and the plant of the HTTR show that in the case of a rapid decrease of the coolant flow rate, the negative reactivity feedback effect of the core brings the reactor power safely to certain stable level without a reactor scram, and that the temperature transient of the reactor core is slow.

JAEA Reports

Rise-to-power test in High Temperature Engineering Test Reactor; Test progress and summary of test results up to 30MW of reactor thermal power

Nakagawa, Shigeaki; Fujimoto, Nozomu; Shimakawa, Satoshi; Nojiri, Naoki; Takeda, Takeshi; Saikusa, Akio; Ueta, Shohei; Kojima, Takao; Takada, Eiji*; Saito, Kenji; et al.

JAERI-Tech 2002-069, 87 Pages, 2002/08

JAERI-Tech-2002-069.pdf:10.12MB

Rise-to-power test in the HTTR has been performed from April 23rd to June 6th in 2000 as phase 1 test up to 10MW, from January 29th to March 1st in 2001 as phase 2 test up to 20MW in the rated operation mode and from April 14th to June 8th in 2001 as phase 3 test up to 20MW in the high temperature test operation mode. Phase 4 test to achieve the thermal reactor power of 30MW started from October 23rd in 2001. On December 7th it was confirmed that the thermal reactor power reached to 30MW and the reactor outlet coolant temperature reached to 850$$^{circ}$$C. JAERI obtained the certificate of pre-operation test from MEXT because all the pre-operation tests by MEXT were passed successfully. From the test results of rise-up-power test up to 30MW, the performance of reactor and cooling system were confirmed, and it was confirmed that an operation of reactor facility could be performed safely. Some problems to be solved were found through tests. By means of solving them, the reactor operation with the reactor outlet coolant temperature of 950$$^{circ}$$C will be achievable.

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