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-ray spectrometer and its performance under intense 
Cs and 
Co radiation fieldsKaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*
Nuclear Instruments and Methods in Physics Research A, 1010, p.165544_1 - 165544_9, 2021/09
Times Cited Count：0 Percentile：0.03(Instruments & Instrumentation)The number of nuclear facilities being decommissioned has been increasing worldwide, in particular following the accident of the Tokyo Electric Power Company Holdings' Fukushima Daiichi Nuclear Power Station in 2011. In these nuclear facilities, proper management of radioactive materials is required. Then, A -ray spectrometer with four segmentations using small volume CeBr
scintillators with a dimension of 
was developed. The four scintillators were coupled to a multi-anode photomultiplier tube specific to intense radiation fields. We performed the -ray exposure study under Cs and Co radiation fields. Under the Cs radiation field, the relative energy resolution at 1375 mSv/h was the relative energy resolution at 1375 mSv/h was 9.2
0.05%, 8.00.08%, 8.0
0.03%, and 9.00.04% for the four channels, respectively.
scintillator under intense -ray fields for nuclear decommissioningKaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research A, 988, p.164900_1 - 164900_8, 2021/02
Times Cited Count：1 Percentile：81.22(Instruments & Instrumentation)An increasing number of nuclear facilities have been decommissioned worldwide following the 2011 accident of the TEPCO' Fukushima Daiichi Nuclear Power Station. During the decommissioning, radioactive materials have to be retrieved under proper management. In this study, a small cubic CeBr spectrometer with dimensions of 5 mm 
5 mm 5 mm was manufactured to perform -ray spectroscopy under intense -ray fields. Furthermore, thanks to a fast digital process unit and a customized photomultiplier, the device could perform -ray spectroscopy at dose rates of over 1 Sv/h. The energy resolution (FWHM) at 662 keV ranged from 4.4% at 22 mSv/h to 5.2% at 1407 mSv/h for a Cs radiation field. Correspondingly, at 1333 keV, it ranged from 3.1% at 26 mSv/h to 4.2% at 2221 mSv/h for a Co radiation field, which suggested to realize -ray assessment of 
Cs, Cs, Co, and 
Eu at dose rates of over 1 Sv/h.
gamma-ray spectrometer suitable for the decommissioning of the Fukushima Daiichi Nuclear Power StationKaburagi, Masaaki; Shimazoe, Kenji*; Otaka, Yutaka*; Uenomachi, Mizuki*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research A, 971, p.164118_1 - 164118_8, 2020/08
Times Cited Count：3 Percentile：76.41(Instruments & Instrumentation)Kaburagi, Masaaki; Torii, Tatsuo; Ogawa, Toru
JAEA-Review 2019-031, 251 Pages, 2020/01
JAEA-Review-2019-031.pdf:57.36MB
There is high expectation for advanced remote technology and robotics to reduce the radiation exposure for workers in harsh nuclear environments such as the decommissioning of the Fukushima Daiichi Nuclear Power Station (FDNPS). However, the radiation tolerance of state-of-the-art key components, sensors and electronic devices, for remote operation is still limited. In order to extend the application of robotics in nuclear energy, it is pertinent to develop "Radiation hardness" of components and "Radiation smartness" in operation procedures. Furthermore, developments of "Radiation measurement" and "Technology to recognize the location and to grasp the surrounding environment", including the radiation imaging of the high dose-rate fields inside the FDNPS and the detection of nuclear fuel debris, are necessary for the future nuclear fuel debris retrieval. This Fukushima Research Conference aims to share the future vision for advancing the remote technology among experts from diverse fields.
Sato, Yuki; Terasaka, Yuta; Miyamura, Hiroko; Kaburagi, Masaaki; Tanifuji, Yuta; Kawabata, Kuniaki; Torii, Tatsuo
Reactor Dosimetry; 16th International Symposium on Reactor Dosimetry (ISRD-16) (ASTM STP 1608), p.428 - 436, 2018/11
Times Cited Count：0 Percentile：0.05Kaburagi, Masaaki; Sato, Yuki; Yoshihara, Yuri*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Torii, Tatsuo
Reactor Dosimetry; 16th International Symposium on Reactor Dosimetry (ISRD-16) (ASTM STP 1608), p.405 - 414, 2018/11
Times Cited Count：0 Percentile：0.05Sato, Yuki; Tanifuji, Yuta; Terasaka, Yuta; Usami, Hiroshi; Kaburagi, Masaaki; Kawabata, Kuniaki; Utsugi, Wataru*; Kikuchi, Hiroyuki*; Takahira, Shiro*; Torii, Tatsuo
Journal of Nuclear Science and Technology, 55(9), p.965 - 970, 2018/09
Times Cited Count：15 Percentile：94.46(Nuclear Science & Technology)-ray imager mounted on a multicopter droneSato, Yuki; Ozawa, Shingo*; Terasaka, Yuta; Kaburagi, Masaaki; Tanifuji, Yuta; Kawabata, Kuniaki; Miyamura, Hiroko; Izumi, Ryo*; Suzuki, Toshikazu*; Torii, Tatsuo
Journal of Nuclear Science and Technology, 55(1), p.90 - 96, 2018/01
Times Cited Count：24 Percentile：98.2(Nuclear Science & Technology)Sato, Yuki; Terasaka, Yuta; Ozawa, Shingo*; Miyamura, Hiroko; Kaburagi, Masaaki; Tanifuji, Yuta; Kawabata, Kuniaki; Torii, Tatsuo
Journal of Instrumentation (Internet), 12(11), p.C11007_1 - C11007_8, 2017/11
Times Cited Count：11 Percentile：62.65(Instruments & Instrumentation)-ray imager mounted on a remotely operated machineSato, Yuki; Kawabata, Kuniaki; Ozawa, Shingo*; Izumi, Ryo*; Kaburagi, Masaaki; Tanifuji, Yuta; Terasaka, Yuta; Miyamura, Hiroko; Kawamura, Takuma; Suzuki, Toshikazu*; et al.
IFAC-PapersOnLine, 50(1), p.1062 - 1066, 2017/07
Times Cited Count：2 Percentile：67.06Kaburagi, Masaaki; Yamada, Hironao*; Miyakawa, Takeshi*; Morikawa, Ryota*; Takasu, Masako*; Kato, Takamitsu*; Uesaka, Mitsuru*
Polymer Journal, 48(2), p.189 - 195, 2016/02
Times Cited Count：4 Percentile：20.63(Polymer Science)We performed molecular dynamics (MD) simulations of telomeric single-stranded DNA and POT1 for 100 ns. The distance between 
(POT1) and O5' (telomeric ssDNA) is calculated to verify the binding system for 100 ns MD. We then calculated the distance between the bases of telomeric DNA ends and the root mean square deviation and gyration radius in single and binding states. We compared the root mean square fluctuations between single and binding states and calculated the number of hydrogen bonds between POT1 and telomeric DNA. There are many hydrogen bonds between Gln94 and the first guanine of the closest TTAGGG sequence in telomeric single-stranded DNA. These Gln94 and the guanine have a large difference in root mean square fluctuation between single and binding states. We found that Gln94 and guanine are important components of the binding system, and they are related to its stability.
Kaburagi, Masaaki*; Watanabe, Ritsuko; Sato, Tatsuhiko; Yokoya, Akinari; Pinak, M.; Katsumura, Yosuke*; Uesaka, Mitsuru*
no journal, ,
In Boron Neutron Capture Therapy (BNCT) borate-ions selectively accumulated in tumor an following neutron capture reactions emit secondary particles, low-energy alpha particle and lithium ion. These particles deposit their energies in tumor effectively. However, there is not enough experimental data to evaluate BNCT biological effectiveness from clinical and research experiments. In our presentation, we introduce results on the research focused on evaluation of the biological effectiveness of the production of DNA strand breaks during BNCT. DNA strand breaks is evaluated based on the microdosimetric data by using Monte Carlo track simulation code. This presentation shows the results of energy deposition, OH radical yields, and DNA strand break yields in aqueous solution. The simulation results are compared with experimental data. Finally we also plan to conduct DNA strand break simulations under conditions as those in actual treatments.
Sato, Yuki; Kishimoto, Aya*; Kaburagi, Masaaki; Kataoka, Jun*; Torii, Tatsuo
no journal, ,
no abstracts in English
Sato, Yuki; Kaburagi, Masaaki; Terasaka, Yuta; Saegusa, Jun; Kawabata, Kuniaki; Wakaida, Ikuo; Torii, Tatsuo
no journal, ,
Yoshihara, Yuri*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Kaburagi, Masaaki; Torii, Tatsuo
no journal, ,
The accident of Fukushima Daiichi Nuclear Power Plant (FDNPP) was occurred on March 11th and the decommissioning of Unit 1-4 of FDNPP has been started since December 2011. Portable radiation imaging technologies are necessary for monitoring the pollution distribution of the inside of the reactor buildings because the measurement environment is highly contaminated and the detector should be mounted on remote-controlled robots. However, existing radiation-imaging systems mainly adopt mechanical collimation to estimate the inserted direction of ray by using lead or tungsten, which make the systems heavy and limit the operation range of the robots. We have been investigated a stacked edge-on silicon strip detector based on hetero-junction technology, which has directivity without any mechanical collimations for imaging The directivity of the 6-layer stacked silicon strip detector was evaluated. The source of 1 MBq Cs-137 was put on the distance of 10 cm from the front of the detector and rotated with the angles of 0, 15, 30, 60, 90 degree, and the detection counts of each rotate angle were measured with thresholds of 180/360 keV.
Sato, Yuki; Kaburagi, Masaaki; Terasaka, Yuta; Saegusa, Jun; Kawabata, Kuniaki; Wakaida, Ikuo; Torii, Tatsuo
no journal, ,
The development of radiation measurement methods in the high dose-rate environment is requested to accelerate implementation of decommissioning of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP). We are now developing the technology which can measure the distribution of the contamination level with radioactive substances inside the building of FDNPP. Light-weight portable gamma camera is to be developed, and is used for drones that can remotely measure the radiation distributions in the high radioactive fields where workers are not allowed to enter and remain there.
Miyamura, Hiroko; Kaburagi, Masaaki; Sato, Yuki; Kawamura, Takuma; Idomura, Yasuhiro; Torii, Tatsuo
no journal, ,
We report the results of experiments for reconstructing three-dimensional volume data of distributions of radiation sources via two reconstruction algorithms from measurement datasets by a Compton camera. To obtain accurate distributions of radiation sources, which were released by the Fukushima Daiichi Nuclear Power Plant accident, detailed measurements of rays are necessary. In this report, as a preliminary experiment, we address three-dimensional reconstruction from measurement data under ideal conditions, using two algorithms: a three-dimensional back-projection method and a list-mode maximum likelihood estimation method. By using these methods, the radiation sources can be accurately reconstructed from the measurement datasets.
Miyamura, Hiroko; Kaburagi, Masaaki; Sato, Yuki; Kawamura, Takuma; Idomura, Yasuhiro; Torii, Tatsuo
no journal, ,
We introduce a project that constructs the ray remote visualization system for capturing the distribution of radiation sources, which were released from the Fukushima Daiichi Nuclear Power Plant. This project executes measurements using a Compton camera mounted on a drone. The measurement datasets are reconstructed for visualizing the radiation source distribution. In this report, we investigated the accuracy of reconstruction for measurement datasets with the constraints, using a three-dimensional back-projection method and a list-mode maximum likelihood estimation method. The measurement datasets are generated by Compton camera measurement simulations for point ray sources, where the number and angle of Compton projection are limited. The reconstruction numerical experiments show that the source distribution data can be reconstructed if the number of projections is sufficiently high.
Sato, Yuki; Ozawa, Shingo*; Izumi, Ryo*; Terasaka, Yuta; Kaburagi, Masaaki; Miyamura, Hiroko; Kawamura, Takuma; Tanifuji, Yuta; Kawabata, Kuniaki; Suzuki, Toshikazu*; et al.
no journal, ,
no abstracts in English
Terasaka, Yuta; Sato, Yuki; Kaburagi, Masaaki; Ozawa, Shingo*; Torii, Tatsuo
no journal, ,
no abstracts in English
