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Journal Articles

Neutron/$$gamma$$-ray discrimination based on the property and thickness controls of scintillators using Li glass and LiCAF(Ce) in a $$gamma$$-ray field

Kaburagi, Masaaki; Shimazoe, Kenji*; Terasaka, Yuta; Tomita, Hideki*; Yoshihashi, Sachiko*; Yamazaki, Atsushi*; Uritani, Akira*; Takahashi, Hiroyuki*

Nuclear Instruments and Methods in Physics Research A, 1046, p.167636_1 - 167636_8, 2023/01

We focus on the thickness and property controls of inorganic scintillators used for thermal neutron detection in intense $$gamma$$-ray fields without considering pulse shape discrimination techniques. GS20$$^{rm{TM}}$$ (a lithium glass) and LiCaAlF$$_6$$:Ce(LiCAF:Ce) cintillators with thicknesses of 0.5 and 1.0 mm, respectively, have been employed. Pulse signals generated by photomultiplier tubes, to which the scintillators were coupled, were inserted into a digital pulse processing unit with 1 Gsps, and the areas of waveforms were integrated for 360 ns. In a $$^{60}$$Co $$gamma$$-ray field, the neutron detection for GS20$$^{rm{TM}}$$ with a 0.5-mm thickness was possible at dose rates of up to 0.919 Gy/h; however, for LiCAF:Ce, neutron detection was possible at 0.473 Gy/h, and it failed at 0.709 Gy/h. Threfore, in a $$^{60}$$Co $$gamma$$-ray field, the neutron/$$gamma$$-ray discrimination of GS20$$^{rm{TM}}$$ was better than that of LiCAF:Ce due to its better energy resolution and higher detection efficiency.

Journal Articles

Preliminary measurement of prompt gamma-ray from nuclear material for the classification of fuel debris and waste

Shiba, Tomooki; Kaburagi, Masaaki; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Nauchi, Yasushi*; Takada, Akira*; Nagatani, Taketeru; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 3 Pages, 2022/10

Journal Articles

Study on identification of materials in fuel debris and waste by neutron induced gamma ray spectroscopy

Nauchi, Yasushi*; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Shiba, Tomooki; Takada, Akira*; Kaburagi, Masaaki; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10

Journal Articles

Identification and quantification of a $$^{60}$$Co radiation source under an intense $$^{137}$$Cs radiation field using an application-specific CeBr$$_3$$ spectrometer suited for use in intense radiation fields

Kaburagi, Masaaki; Shimazoe, Kenji*; Kato, Masahiro*; Kurosawa, Tadahiro*; Takahashi, Hiroyuki*

Journal of Nuclear Science and Technology, 59(8), p.983 - 992, 2022/08

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Development of the multi-cubic $$gamma$$-ray spectrometer and its performance under intense $$^{137}$$Cs and $$^{60}$$Co radiation fields

Kaburagi, 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:0.02(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 $$gamma$$-ray spectrometer with four segmentations using small volume CeBr$$_{3}$$ scintillators with a dimension of $$5 times 5 times 5$$ $$rm{mm}^3$$ was developed. The four scintillators were coupled to a multi-anode photomultiplier tube specific to intense radiation fields. We performed the $$gamma$$-ray exposure study under $$^{137}$$Cs and $$^{60}$$Co radiation fields. Under the $$^{137}$$Cs radiation field, the relative energy resolution at 1375 mSv/h was the relative energy resolution at 1375 mSv/h was 9.2$$pm$$0.05%, 8.0$$pm$$0.08%, 8.0$$pm$$0.03%, and 9.0$$pm$$0.04% for the four channels, respectively.

Journal Articles

Gamma-ray spectroscopy with a CeBr$$_3$$ scintillator under intense $$gamma$$-ray fields for nuclear decommissioning

Kaburagi, 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:9 Percentile:90.18(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$$_3$$ spectrometer with dimensions of 5 mm $$times$$ 5 mm $$times$$ 5 mm was manufactured to perform $$gamma$$-ray spectroscopy under intense $$gamma$$-ray fields. Furthermore, thanks to a fast digital process unit and a customized photomultiplier, the device could perform $$gamma$$-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 $$^{137}$$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 $$^{60}$$Co radiation field, which suggested to realize $$gamma$$-ray assessment of $$^{134}$$Cs, $$^{137}$$Cs, $$^{60}$$Co, and $$^{154}$$Eu at dose rates of over 1 Sv/h.

Journal Articles

A Cubic CeBr$$_{3}$$ gamma-ray spectrometer suitable for the decommissioning of the Fukushima Daiichi Nuclear Power Station

Kaburagi, 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:7 Percentile:67.5(Instruments & Instrumentation)

JAEA Reports

RADREMOTE 2018; Proceedings of The 5th Fukushima Research Conference (FRC) 2018; Radiation hardness, smartness and measurement in remote technology for the decommissioning of the Fukushima Daiichi Nuclear Power Station

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.

Journal Articles

Image reconstruction of radioactive contamination due to the Fukushima-Daiichi Nuclear Power Station Accident using a compact Compton camera

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:0.05

Journal Articles

Gamma-ray imaging system for Fukushima Daiichi Nuclear Power Plant using silicon strip detector

Kaburagi, 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:0.05

Journal Articles

Radiation imaging using a compact Compton camera inside the Fukushima Daiichi Nuclear Power Station building

Sato, 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:30 Percentile:96.56(Nuclear Science & Technology)

Journal Articles

Remote radiation imaging system using a compact $$gamma$$-ray imager mounted on a multicopter drone

Sato, 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:41 Percentile:98.09(Nuclear Science & Technology)

Journal Articles

Development of compact Compton camera for 3D image reconstruction of radioactive contamination

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:17 Percentile:65.53(Instruments & Instrumentation)

Journal Articles

Radiation imaging system using a compact $$gamma$$-ray imager mounted on a remotely operated machine

Sato, 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:3 Percentile:66.55

Journal Articles

Molecular dynamics simulation of telomeric single-stranded DNA and POT1

Kaburagi, Masaaki; Yamada, Hironao*; Miyakawa, Takeshi*; Morikawa, Ryota*; Takasu, Masako*; Kato, Takamitsu*; Uesaka, Mitsuru*

Polymer Journal, 48(2), p.189 - 195, 2016/02

AA2015-0476.pdf:1.08MB

 Times Cited Count:5 Percentile:19(Polymer Science)

We performed molecular dynamics (MD) simulations of telomeric single-stranded DNA and POT1 for 100 ns. The distance between $$C_alpha$$ (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.

Oral presentation

The Evaluation DNA radiation damage in BNCT by track structured Monte Carlo simulation code

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.

Oral presentation

Remote technology development for function advancement of research base, 7; Feasibility study of a portable Compton camera for visualizing radioactive substances

Sato, Yuki; Kishimoto, Aya*; Kaburagi, Masaaki; Kataoka, Jun*; Torii, Tatsuo

no journal, , 

no abstracts in English

Oral presentation

R&Ds on remote technology and radiation measurements in JAEA towards the decommissioning of FDNPP

Sato, Yuki; Kaburagi, Masaaki; Terasaka, Yuta; Saegusa, Jun; Kawabata, Kuniaki; Wakaida, Ikuo; Torii, Tatsuo

no journal, , 

Oral presentation

Study on silicon semiconductor detector for visualization the pollution distribution in the Fukushima Daiichi Nuclear Power Plant

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 $$gamma$$ 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.

Oral presentation

R&Ds on remote radiation measurement technology in JAEA towards the decommissioning of FDNPP

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.

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