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Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.850 - 854, 2021/10
no abstracts in English
Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*
JPS Conference Proceedings (Internet), 33, p.011019_1 - 011019_7, 2021/03
The multi-turn charge-exchange H
beam injection scheme with stripper foils is one of the key techniques to achieve a MW-class high power proton beam. The J-PARC RCS adopts Hybrid type Boron-doped Carbon (HBC) stripper foil, which was developed in KEK to improve the lifetime. Indeed, the RCS user operation confirmed that HBC foil has the great advantage of a longer lifetime against high beam irradiation. To examine characteristics of the HBC foils, various beam studies were performed, such as the stripping efficiency measurement and long-term observation with an H beam in the J-PARC RCS, foil analysis using RBS, EDR and PIXE methods, and SEM and TEM observation after the ion beam irradiation in Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) on National Institutes for Quantum and Radiological Science and Technology (QST). Recently, the deposition apparatus for the HBC foils from the KEK Tsukuba-site was relocated to the JAEA Tokai-site, and we started fabrication of new HBC foil in 2017. (The new one fabricated in JAEA we call J-HBC foil.) And, we continue investigations in TIARA with the J-HBC foils. Furthermore, in-depth researches by changing the process parameters of the foil deposition are carried on. Recent results suggest that the amount of the boron doped in the foil is more important parameter than the ratio of the discharge amount of carbon from cathode and anode electrodes. In this presentation, we will report the details of recent analysis of the J-HBC foil.
Yamamoto, Keiichi; Takeuchi, Tomoaki; Sano, Tadafumi*; Homma, Ryohei*; Kimura, Nobuaki; Otsuka, Noriaki; Kosuge, Fumiaki*; Nakajima, Ken*; Tsuchiya, Kunihiko
JAEA-Technology 2014-028, 56 Pages, 2015/01
JAEA-Technology-2014-028.pdf:9.23MB
Development of the reactor measurement system was started to obtain real-time in-core nuclear and thermal information, where the quantity measurement of brightness of Cherenkov light was applied. The system would be applied as monitoring system in severe accidents and for advanced operation management technology in existing LWRs. In this report, the calculation and the observation results were summarized about the quantity of the Cherenkov light caused by the 
and 
ray emitted from the fuels in the core of Kyoto University Research Reactor.
Shiga, Hideaki*; Taki, Junichi*; Washiyama, Koshin*; Yamamoto, Jumpei*; Kinase, Sakae; Okuda, Koichi*; Kinuya, Seigo*; Watanabe, Naoto*; Tonami, Hisao*; Koshida, Kichiro*; et al.
PLOS ONE (Internet), 8(2), p.e57671_1 - e57671_8, 2013/02
Times Cited Count：19 Percentile：68.44(Multidisciplinary Sciences)Amazawa, Hiroya; Sakai, Akihiro; Nakata, Hisakazu; Hara, Hironori; Kurosawa, Ryohei; Yamamoto, Masayuki*; Kawata, Yosuke*; Sakamoto, Yoshiaki
JAEA-Technology 2012-031, 338 Pages, 2012/10
JAEA-Technology-2012-031.pdf:19.43MB
JAEA is responsible for siting a proper location to establish new disposal facilities with siting criterion and procedure, in consideration of transparency and impartial for the siting process, based on Plan Concerning the Disposal Business Execution. As a part of the study to draw up siting criterion and procedure, Sensitivity analysis of the disposal facilities from the viewpoint of dose evaluation and cost estimation under various siting condition will be carried out. Therefore, Conceptual design of disposal facilities as a reference case is necessary. The basic condition of the design conforms to the property, quantity, radioactivity of waste packages, technical standards and likely siting condition. This report summarizes the results of the reasonable design of our disposal facilities and the layout of the place of activity where the disposal facilities and associated facilities to be installed.
Otsuka, Noriaki; Yamamoto, Keiichi; Takeuchi, Tomoaki; Kimura, Nobuaki; Matsui, Yoshinori; Tsuchiya, Kunihiko; Sano, Tadafumi*; Nakajima, Ken*; Homma, Ryohei*
no journal, ,
no abstracts in English
rays irradiation to examine measures for corrosion inhibition of reactor vessel steelsNakano, Junichi; Yamamoto, Masahiro; Tsukada, Takashi; Yamagata, Ryohei
no journal, ,
In the Fukushima Daiichi Nuclear Power Station, seawater was injected into the reactor cores as an emergency measure for the core cooling. Radiation dose is high in the primary containment vessels (PCVs) because of the fuel debris and the fission products. It is considered that corrosion of the PCVs and the reactor pressure vessels is accelerated by the products of water radiolysis. Corrosion tests were conducted in diluted seawater at under -rays irradiation. Weight loss in the diluted seawater irradiated with dose rates 
0.2 kGy/h was comparable with that without irradiation. Weight loss in the diluted seawater irradiated with dose rates 
0.6 kGy/h was higher than that without irradiation. Under irradiation, weight loss in N
atmosphere was lower than that in air atmosphere. To reduce weight loss, hydrazine (NH
) addition in air atmosphere was not effective while NH addition in N atmosphere was effective.
Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*
no journal, ,
The multi-turn charge-exchange H beam injection scheme with stripper foils is one of the key techniques to achieve a MW-class high power proton beam. The J-PARC RCS adopts Hybrid type Boron-doped Carbon (HBC) stripper foil, which was developed in KEK to improve the lifetime. Indeed, the RCS user operation confirmed that HBC foil has the great advantage of a longer lifetime against high beam irradiation. To examine characteristics of the HBC foils, various beam studies were performed, such as the stripping efficiency measurement and long-term observation with an H beam in the J-PARC RCS, foil analysis using RBS, EDR and PIXE methods, and SEM and TEM observation after the ion beam irradiation in Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) on National Institutes for Quantum and Radiological Science and Technology (QST). Recently, the deposition apparatus for the HBC foils from the KEK Tsukuba-site was relocated to the JAEA Tokai-site, and we started fabrication of new HBC foil in 2017. (The new one fabricated in JAEA we call J-HBC foil.) And, we continue investigations in TIARA with the J-HBC foils. Furthermore, in-depth researches by changing the process parameters of the foil deposition are carried on. Now, we developed new types of foils which were made by arc discharge method by using a pure carbon rod for ether the anode electrode or the cathode electrode. As the results of the beam irradiation tests for the new types of HBC foils, it was suggested that the boron being carried in from the anode electrode plays an important part in the functioning of the stripper foil. The new knowledge will mark a milestone in the improvement of the stripper foil.
Yamamoto, Ryohei*; Sugita, Kento*; Taira, Yoshitaka*; Hirade, Tetsuya
no journal, ,
Age-Momentum Correlation (AMOC) can observe the Doppler broadening of time-resolved annihilation gamma rays. The annihilation rate depends on the positron state, and it is possible to know if positrons are trapped in structural defects in a sample. Moreover, the Doppler broadening gives the information of impurities around the defects. Positrons from radioactive isotopes cannot penetrate a deep region of bulk material. The application of radioisotopes is difficult for the measurements under severe conditions such as in high pressure or a high temperature. Therefore, we have developed a GiAMOC (Gamma-ray induced AMOC) system, which is a measurement method for generating positrons in a sample using inverse Thomson scattered gamma rays in UVSOR-III. In addition, the developed measurement system was used to measure the reference material for positron lifetime measurement.
Taira, Yoshitaka*; Sugita, Kento*; Yamamoto, Ryohei*; Okano, Yasuaki*; Hirade, Tetsuya
no journal, ,
We are developing gamma-ray-induced positron annihilation spectroscopy at UVSOR-III. This method enables defect analysis of the entire bulk sample with a thickness of several cm, which was difficult to measure with the conventional method using a positron radiation source. Currently, the user use of the positron lifetime measurement method is being developed, and in parallel with this, the coincidence Doppler broadening method, the age-momentum correlation measurement method, and the spin-polarized positron spectroscopy are being developed. Here, we will describe the development status of them.
Taira, Yoshitaka*; Sugita, Kento*; Yamamoto, Ryohei*; Okano, Yasuaki*; Hirade, Tetsuya
no journal, ,
Positron annihilation spectroscopy is a powerful analytical method to observe single-atom vacant defects in crystals and microvoids in insulating materials. UVSOR-III installed at the Institute of Molecular Science promotes the development and user use of Gamma-ray induced positron annihilation spectroscopy (GiPAS) by ultrashort pulse gamma rays. Since the ultrashort pulse gamma rays generate positrons inside the material by pair production, positron annihilation experiments of bulk materials with a thickness of several cm can be performed non-destructively. In addition, since the sample is irradiated with gamma rays from the outside, measurement can be performed in an environment such as high temperature, high pressure, and immersion. We report on the generation of ultrashort pulse gamma rays and the development status of the positron lifetime measurement, and the positron age-momentum correlation measurement.
Yamamoto, Ryohei*; Taira, Yoshitaka*; Sugita, Kento*; Hirade, Tetsuya; Takashima, Yoshifumi*; Kato, Masahiro*
no journal, ,
Positron annihilation spectroscopy is a powerful analytical method that can observe single-atom vacant defects in crystals and microvoids in insulating materials. UVSOR-III installed at the Institute of Molecular Science is promoting the development and user use of Gamma-ray induced positron annihilation spectroscopy (GiPAS) by ultrashort pulse gamma rays. We have succeeded in positron lifetime measurement and lifetime momentum correlation measurement. This time, we succeeded in detecting the process of defect capture in the positron age-momentum correlation measurement of strained steel materials.
