Zhan, Y.*; Kuwata, Yusuke*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi
Experimental Thermal and Fluid Science, 120, p.110249_1 - 110249_12, 2021/01
Hirooka, Shun; Matsumoto, Taku; Kato, Masato; Sunaoshi, Takeo*; Uno, Hiroki*; Yamada, Tadahisa*
Journal of Nuclear Materials, 542, p.152424_1 - 152424_9, 2020/12
The measurement of oxygen potential was conducted at 1,673, 1,773, and 1,873 K for (UPuAm)O and at 1,873 and 1,923 K for (UPuAmNp)O by using a thermo-gravimeter and an oxygen sensor. Am inclusion in terms of substituting the U significantly increased the oxygen potential. Similarly, the inclusion of Np as a substitute for U increased the oxygen potential; however, the effect was not as large as that with the Pu or Am addition at the same rate. The results were analyzed via defect chemistry and certain defect formations were suggested in the reducing region and the near-stoichiometric region by plotting the relationship between PO and the deviation from the stoichiometry. The equilibrium constants of the defect reactions were arranged to reproduce the experiment such that Am/Np contents were included in the entropy with coefficients fitting the experimental data.
Watanabe, Masashi; Kato, Masato; Sunaoshi, Takeo*
Journal of Nuclear Materials, 542, p.152472_1 - 152472_7, 2020/12
The oxygen self-diffusion coefficients in near stoichiometric (U,Pu)O at high temperatures were successfully measured by thermogravimetry combined with the oxygen isotope exchange method. The activation energy for oxygen diffusion in the stoichiometric composition of (U,Pu)O was evaluated from experimental data, and the value was determined to be 248 kJ/mol. In addition, the defect migration energies of (U,Pu)O were derived, and the oxygen self-diffusion coefficients were evaluated using these. As a result, good agreement was found between the experimental data and the oxygen self-diffusion coefficients calculated using the defect migration energies.
Yoneda, Yasuhiro; Noguchi, Yuji*
Japanese Journal of Applied Physics, 59(SP), p.SPPA01_1 - SPPA01_7, 2020/11
We investigate A-site cation ordering in the ferroelectric perovskite BiNaTiO (BNT) by synchrotron X-ray total scattering. Although BNT has a problem of a low depolarization temperature, it is promising a lead-free piezoelectric material. Since the depolarization temperature is presumed to correspond to a relaxer like gradual order-disorder phase transition, local structure analysis is necessary to understand the structure of the diorder phase. Through this approach, the elusive connection between chemical heterogeneity and structural heterogeneity is revealed. Because of the large randomness, the Ti off-center shift is averaged out beyond the unit cell and the structure becomes very close to the average structure beyond the unit cell.
Sanada, Yukihisa; Yoshimura, Kazuya; Urabe, Yoshimi*; Iwai, Takeyuki*; Katengeza, E. W.*
Journal of Environmental Radioactivity, 223-224, p.106397_1 - 106397_9, 2020/11
Suzudo, Tomoaki; Takamizawa, Hisashi; Nishiyama, Yutaka; Caro, A.*; Toyama, Takeshi*; Nagai, Yasuyoshi*
Journal of Nuclear Materials, 540, p.152306_1 - 152306_10, 2020/11
Spinodal decomposition in thermally aged Fe-Cr alloys leads to significant hardening, which is the direct cause of the so-called 475C-embrittlement. To illustrate how spinodal decomposition induces hardening by atomistic interactions, we conducted a series of numerical simulations as well as reference experiments. The numerical results indicated that the hardness scales linearly with the short-range order (SRO) parameter, while the experimental result reproduced this relationship within statistical error. Both seemingly suggest that neighboring Cr-Cr atomic pairs essentially cause hardening, because SRO is by definition uniquely dependent on the appearance probability of such pairs. A further numerical investigation supported this notion, as it suggests that the dominant cause of hardening is the pinning effect of dislocations passing over such Cr-Cr pairs.
Abe, Satoshi; Studer, E.*; Ishigaki, Masahiro; Shibamoto, Yasuteru; Yonomoto, Taisuke
Nuclear Engineering and Design, 368, p.110785_1 - 110785_14, 2020/11
Yokoyama, Sumi*; Ezaki, Iwao*; Tatsuzaki, Hideo*; Tachiki, Shuichi*; Hirao, Kazushige*; Aoki, Katsunori; Tanimura, Yoshihiko; Hoshi, Katsuya; Yoshitomi, Hiroshi; Tsujimura, Norio
Radiation Measurements, 138, p.106399_1 - 106399_5, 2020/11
Funaki, Hironori; Sakuma, Kazuyuki; Nakanishi, Takahiro; Yoshimura, Kazuya; Katengeza, E. W.*
Science of the Total Environment, 743, p.140668_1 - 140668_9, 2020/11
Ikebe, Yurie*; Oshima, Masumi*; Bamba, Shigeru*; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Toyoshima, Atsushi*; Bi, C.*; Seto, Hirofumi*; Amano, Hikaru*; et al.
Applied Radiation and Isotopes, 164, p.109106_1 - 109106_7, 2020/10
Boron Neutron Capture Therapy (BNCT) is a radiotherapy for the treatment of intractable cancer. In BNCT precise determination of B concentration in whole blood sample before neutron irradiation is crucial for control of the neutron irradiation time and the neutron dosimetry. We have applied the Charged Particle Activation Analysis (CPAA) to non-destructive and accurate determination of B concentration in whole blood sample. The experiment was performed at JAEA Tandem Accelerator using an 8 MeV proton beam. The 478 keV ray of Be produced in the B(p,)Be reaction was used to quantify the B, and rays of Co originating from the reaction with Fe in blood was used to normalize the -ray intensity. The results demonstrated that the present CPAA method can be applied to the determination of the B concentration in the blood sample.
Sato, Yosuke*; Sekiyama, Tsuyoshi*; Fang, S.*; Kajino, Mizuo*; Qurel, A.*; Qulo, D.*; Kondo, Hiroaki*; Terada, Hiroaki; Kadowaki, Masanao; Takigawa, Masayuki*; et al.
Atmospheric Environment; X (Internet), 7, p.100086_1 - 100086_12, 2020/10
The third model intercomparison project for investigating the atmospheric behavior of Cs emitted during the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident (FDNPP-MIP) was conducted. A finer horizontal grid spacing (1 km) was used than in the previous FDNPP-MIP. Nine of the models used in the previous FDNPP-MIP were also used, and all models used identical source terms and meteorological fields. Our analyses indicated that most of the observed high atmospheric Cs concentrations were well simulated, and the good performance of some models improved the performance of the multi-model ensemble. The analyses also confirmed that the use of a finer grid resolution resulted in the meteorological field near FDNPP being better reproduced. The good representation of the wind field resulted in the reasonable simulation of the narrow distribution of high deposition amount to the northwest of FDNPP and the reduction of the overestimation over the area to the south of FDNPP. In contrast, the performance of the models in simulating plumes observed over the Nakadori area, the northern part of Gunma, and the Tokyo metropolitan area was slightly worse.
Ishigaki, Masahiro; Abe, Satoshi; Shibamoto, Yasuteru; Yonomoto, Taisuke
Nuclear Engineering and Design, 367, p.110790_1 - 110790_15, 2020/10
no abstracts in English
Sato, Yuki; Minemoto, Kojiro*; Nemoto, Makoto*; Torii, Tatsuo
Nuclear Instruments and Methods in Physics Research A, 976, p.164286_1 - 164286_6, 2020/10
Okudaira, Takuya; Oku, Takayuki; Ino, Takashi*; Hayashida, Hirotoshi*; Kira, Hiroshi*; Sakai, Kenji; Hiroi, Kosuke; Takahashi, Shingo*; Aizawa, Kazuya; Endo, Hitoshi*; et al.
Nuclear Instruments and Methods in Physics Research A, 977, p.164301_1 - 164301_8, 2020/10
Ono, Masato; Hanawa, Yoshio; Sonobe, Hiroshi; Nishimura, Arashi; Sugaya, Naoto; Iigaki, Kazuhiko
JAEA-Technology 2020-010, 14 Pages, 2020/09
In response to new standard for regulating research and test reactor which is enforced December 18, 2013, it was carried out assessment of the probability of aircraft crashing for HTTR. According to assessment method provided in the Assessment Criteria of the Probability of Aircraft Crashing on Commercial Power Reactor Facilities, assessment was conducted targeting reactor building, spent fuel storage building and cooling tower. As a result, it was confirmed that the probability was 5.9810, which is lower than the assessment criteria 10.
Nishiyama, Yutaka; Iwai, Masaki; Chiba, Yusuke; Tsubaki, Hirohiko; Ono, Hayato*; Hayasaka, Toshiro*; Hanyu, Toshinori*
JAEA-Technology 2020-007, 18 Pages, 2020/09
Maintenance and Operation Section for Remote Control Equipment in Naraha Center for Remote Control Technology Development is the main part of the nuclear emergency response team of Japan Atomic Energy Agency (JAEA) in full-scale operation starts on the 1st of April, 2020. The section needs to develop equipment for JAEA nuclear emergency. Because of dealing the full-scale operation, the section designed and produced two sets of Multi-joint Manipulator or (for Opening Doors) against Nuclear Disaster in order to put them on two crawler robots in 2018 fiscal year. And the section also designed and produced a Crawler Robot for Opening and Closing Manual Valves in 2019 fiscal year. This report shows two sets of Multi-Joint Manipulator (for Opening Doors) and a Crawler Robot for Opening and Closing Manual Valves designed and produced by Maintenance and Operation Section for Remote Control Equipment in 2018 and 2019 fiscal year.
Togawa, Orihiko; Hayakawa, Tsuyoshi; Tanaka, Tadao; Yamamoto, Kazuya; Okuno, Hiroshi
JAEA-Review 2020-017, 36 Pages, 2020/09
In 2010, the government of Japan joined the Response and Assistance Network (RANET) of the International Atomic Energy Agency (IAEA), in order to contribute to offering international assistance in the case of a nuclear accident or radiological emergency. At that occasion, the Japan Atomic Energy Agency (JAEA) was registered as the National Assistance Capability (NAC) having resources capable of the External Based Support (EBS) in the following seven areas: (1) aerial survey, (2) radiation monitoring, (3) environmental measurements, (4) assessment and advice, (5) internal dose assessment, (6) bioassay and (7) dose reconstruction. After the registration, three inquiries were directed to the JAEA about a possibility of its support. However, the JAEA's assistance has not eventually been realized. On the other hand, the JAEA participated almost every year in the international Convention Exercise (ConvEx) carried out by the IAEA in connection with RANET. This report describes an outline of the RANET and related activities of the JAEA for RANET registration and participation in the ConvEx.
Nuclear Emergency Assistance and Training Center
JAEA-Review 2020-016, 67 Pages, 2020/09
The Japan Atomic Energy Agency (JAEA) is one of the designated public institutions, which is an agency dealing with an emergency situation in cooperation with the Japanese and local governments under the Disaster Countermeasures Basic Act and under the Armed Attack Situation Response Law. JAEA has, therefore, responsibilities of providing technical assistances to the Japanese and local governments in case of nuclear or radiological emergencies based on these Acts. To fulfill the assistances, the JAEA has prepared the Nuclear Emergency Support Measures Regulation, Disaster Prevention Work Plan and Civil Protection Work Plan. The Nuclear Emergency Assistance and Training Center (NEAT) is the main center of the technical assistance in case of emergency, and dispatches experts of JAEA, supplies equipment and materials and gives technical advice and information, to the Japanese and local governments for emergency based on the regulation and plans. In normal time, the NEAT provides the technical assistances such as the exercises and training courses concerning the nuclear preparedness and response to the JAEA experts and also to emergency responders including the Japanese and local government officers. This report introduces the results of activities in Japanese Fiscal Year 2019, conducted by NEAT in accordance with the third medium and long-term plan for the period from Japanese Fiscal Year 2015 to 2021.
Asakura, Kazuki; Shimomura, Yusuke; Donomae, Yasushi; Abe, Kazuyuki; Kitamura, Ryoichi
JAEA-Review 2020-015, 66 Pages, 2020/09
The disposal of radioactive waste from the research facility need to calculated from the radioactivity concentration that based on variously nuclear fuels and materials. In Japan Atomic Energy Oarai Research and Development Institute, the study on considering disposal is being advanced among the facilities which generate radioactive waste as well as the facilities which process radioactive waste. This report summarizes a study result in FY2019 about the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute.
JAEA-Review 2020-014, 63 Pages, 2020/09
J-PARC Center has been promoting several public relations activities to appeal the cutting-edge research programs and their outputs to the citizen, especially in Ibaraki prefecture and Tokai village. The Public Relations Section put weight to outreach events as the best tool for this purpose, such as site tour, open house, and summer school. Here the outreach activities are summarized mainly from FY2012 to FY2019.