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Matsuoka, Amane; Yasumune, Takashi; Kojima, Nobuhiro; Miyauchi, Hideaki; Takasaki, Koji; Hashimoto, Makoto
JAEA-Review 2021-055, 11 Pages, 2021/12
JAEA-Review-2021-055.pdf:1.12MB
The dose limit for the eye lens was lowered on April 1 2021, and a 3 mm dose equivalent was added to the calculation. The guidelines require that lens dosimeters be worn and managed when there is a risk of exceeding control standards. In this report, in order to examine future management methods, we investigated whether work that might exceed the equivalent dose limit was performed in the past. As a result of the investigation, the exposure dose for all works after fiscal year 2008 was sufficiently low compared to the equivalent dose limit. For this reason, it is considered that there is no need for additional management of wearing a personal dosimeter near the eyes for the work that is normally performed. In the future, as in the past, the basic management method will be to wear a dosimeter only on the basic part of the trunk under uniform exposure conditions, and to wear a dosimeter on the basic part of the trunk and the maximum dose part under nonuniform exposure conditions. When performing work with a high exposure dose to the eye lens, a dosimeter should be worn near the eye to measure the 3 mm dose equivalent.
Takasaki, Koji; Yasumune, Takashi; Hashimoto, Makoto; Maeda, Koji; Kato, Masato; Yoshizawa, Michio; Momose, Takumaro
JAEA-Review 2019-003, 48 Pages, 2019/03
JAEA-Review-2019-003.pdf:3.81MB
June 6, 2017, at Plutonium Fuel Research Facility in Oarai Research and Development Center of JAEA, when five workers were inspecting storage containers containing plutonium and uranium, resin bags in a storage container ruptured, and radioactive dust spread. Though they were wearing a half face mask respirator, they inhaled radioactive materials. In the evaluation of the internal exposure dose, the aerodynamic radioactive median diameter (AMAD) is an important parameter. We measured 14 smear samples and a dust filter paper with imaging plates, and estimated the AMAD by image analysis. As a result of estimating the AMAD, from the 14 smear samples, the AMADs are 4.3 to 11 
m or more in the case of nitrate plutonium, and the AMADs are 5.6 to 14 m or more in the case of the oxidized plutonium. Also, from the dust filter paper, the AMAD is 3.0 m or more in the case of nitrate plutonium, and the AMAD is 3.9 m or more in the case of the oxidized plutonium.
Takasaki, Koji; Yasumune, Takashi; Onishi, Takashi; Nakamura, Keisuke; Ishimi, Akihiro; Ito, Chikara; Osaka, Masahiko; Ono, Masashi*; Hatakeyama, Shuichi*; Takahashi, Hiroyuki*; et al.
JAEA-Research 2013-043, 33 Pages, 2014/01
JAEA-Research-2013-043.pdf:13.81MB
In the Fukushima Daiichi Nuclear Power Plant, it is assumed that the core fuels melted partially or wholly, and the normal technique of accounting for a fuel assembly is not applicable. Therefore, it is necessary to develop the transparent and rational technique of accounting in the process of collection and storage of fuel debris. In this research, an application of the superconducting phase Transition Edge Sensor microcalorimeter (TES microcalorimeter) is studied for the accounting of nuclear materials in the fuel debris. It is expected that the detailed information of nuclear materials and fission products in fuel debris is obtained by using a high-resolution characteristic of TES microcalorimeter. In this report, the principle of TES microcalorimeter, the measurement experiment using TES in JAEA, and the simulated calculation using the EGS5 code system are summarized.
-doped YAlO
in the temperature range from 4.2 to 175 KYasumune, Takashi; Kurihara, Masakazu*; Maehata, Keisuke*; Ishibashi, Kenji*; Yoshikawa, Akira*
Nuclear Instruments and Methods in Physics Research A, 726, p.37 - 40, 2013/08
Times Cited Count：1 Percentile：11.98(Instruments & Instrumentation)Yb-doped yttrium-aluminum perovskites (YAP:Yb) are expected to be scintillator materials with high light yield and short scintillation decay time because of their charge transfer (CT) luminescence. Since the CT luminescence of Yb is strongly affected by thermal quenching, to use YAP:Yb as a scintillator material, it is necessary to measure the scintillation properties of YAP:Yb at low temperatures. Since it is difficult to detect scintillation light at low temperatures, scintillation properties of YAP:Yb characterized by irradiating with 
-rays or other radiation below 100 K have not been reported. We conducted measurements of the temperature dependence of emission wavelength spectrum of YAP:Yb by irradiating with 
-rays from a 
Sr/Y source in the temperature range from 4.2 K to 175 K. The emission peak at around 340-350 nm and 500-520 nm were observed in the emission wavelength spectra. The light yield of YAP:Yb was characterized by using an avalanche photodiode in detection of 662 keV -rays from a 
Cs source in the temperature range from 50 K to 175 K. The light yield increased with decreasing temperature and reached 11,000 photons/MeV at a temperature of 4.2 K.
Nakamura, Keisuke; Maeda, Makoto*; Yasumune, Takashi*; Maehata, Keisuke*; Ishibashi, Kenji*; Tanaka, Keiichi*; Umeno, Takahiro*; Takasaki, Koji; Momose, Takumaro
Radiation Protection Dosimetry, 146(1-3), p.88 - 91, 2011/07
Times Cited Count：1 Percentile：10.97(Environmental Sciences)A Transition Edge Sensor (TES) microcalorimeter has been developed for use as an energy dispersive X-ray spectrometer. A TES microcalorimeter is a thermal detector used to measure the energy of an incident photon with increase in temperature. In this work, a TES microcalorimeter with a 5m Au absorber was developed for use in measuring LX rays emitted from transuranium elements. Furthermore, as a cooling system a dilution refrigerator utilizing a Gifford-McMahon refrigerator was used, which needs no liquid helium. The performance of the TES microcalorimeter was evaluated by measuring the LX rays emitted by an 
Am source. This system proved effective in the measurement of the LX rays because the full width at half maximum of the L
X ray was about 80 eV.
Maehata, Keisuke*; Nakamura, Keisuke*; Yasumune, Takashi*; Ishibashi, Kenji*; Takasaki, Koji; Tanaka, Keiichi*; Odawara, Akikazu*; Nagata, Atsushi*
Journal of Nuclear Science and Technology, 47(3), p.308 - 313, 2010/03
Times Cited Count：5 Percentile：36.7(Nuclear Science & Technology)A phase transition edge sensor (TES) microcalorimeter was developed for the energy dispersive measurement of LX-ray photons emitted from transuranium elements. The phase transition temperature of the TES was designed to be 200 mK by using bilayer structure of Au of 120 nm thick and Ti of 50 nm thick. The Au layer of 5.0 m thick was deposited on the Au/Ti bilayer for absorption efficiency of 50% and counting rate of 100 counts per second in the detection of LX-ray photons with the energy from 10 to 20 keV. The TES microcalorimeter was operated for the detection of LX-ray photons emitted from Am, 
Pu and 
Pu sources. The decay time constant of 180 s of detection signal pulses allowed the TES microcalorimeter operating with the counting rate higher than 100 counts per second. The energy resolution was obtained to be 50 eV of FWHM value for a peak corresponding to 
Np L
X-ray of 17.75 keV.
-rays using a TES microcalorimeter with a thick Sn absorber; Spectrum analysis with Monte Carlo simulationYasumune, Takashi; Takasaki, Koji; Onishi, Takashi; Koyama, Shinichi; Hatakeyama, Shuichi*; Ono, Masashi*; Takahashi, Hiroyuki*
no journal, ,
Superconducting transition edge sensors (TES) have been developed for identification of plutonium and minor actinides. We have developed TES with a thick Sn absorber to detect X-rays and -rays. Energy dispersive spectroscopy measurements of an actinide source were conducted by the TES with a Sn absorber to demonstrate the potential for hard X-ray and -ray detection. We also performed a Monte Carlo simulation using EGS5 code in order to analyze the obtained results.
Nakamura, Keisuke; Maeda, Makoto*; Aoki, Katsunori; Yasumune, Takashi; Takasaki, Koji; Maehata, Keisuke*; Iyomoto, Naoko*; Ishibashi, Kenji*; Mitsuda, Kazuhisa*; Tanaka, Keiichi*
no journal, ,
no abstracts in English
rays emitted from Np sources with using TES microcalorimetersYasumune, Takashi; Takasaki, Koji; Ito, Chikara; Ono, Masashi*; Irimatsukawa, Tomoya*; Takahashi, Hiroyuki*
no journal, ,
no abstracts in English
-rays using a TES microcalorimeter with a Sn absorber; Analysis of energy spectrum with Monte Carlo simulationYasumune, Takashi; Takasaki, Koji; Nakamura, Keisuke; Ono, Masashi*; Irimatsukawa, Tomoya*; Takahashi, Hiroyuki*
no journal, ,
no abstracts in English
Kato, Yoshinari; Hashimoto, Makoto; Miyauchi, Hideaki; Yasumune, Takashi; Ogawa, Ryuichiro; Goto, Shingo; Ochiai, Yukihiro*; Matsui, Junki
no journal, ,
no abstracts in English
Kato, Yoshinari; Hashimoto, Makoto; Miyauchi, Hideaki; Yasumune, Takashi; Maeda, Eita; Takasaki, Koji; Yoshizawa, Michio; Momose, Takumaro
no journal, ,
no abstracts in English
Yasumune, Takashi; Kato, Yoshinari; Maeda, Eita; Miyauchi, Hideaki; Hashimoto, Makoto; Takasaki, Koji
no journal, ,
no abstracts in English
